the short - term periodicities of the daily sunspot area fluctuations from august 1923 to october 1933 are discussed. for these data   the correlative analysis indicates negative correlation for the periodicity of about @xmath0 days, but the power spectrum analysis indicates a statistically significant peak in this time interval.   a new method of the diagnosis of an echo - effect in spectrum is proposed and it is stated that the 155-day periodicity is a harmonic of the periodicities from the interval of @xmath1 $ ] days.    the autocorrelation functions for the daily sunspot area fluctuations and for the fluctuations of the one rotation time interval in the northern hemisphere, separately for the whole solar cycle 16 and for the maximum activity period of this cycle do not show differences, especially in the interval of @xmath2 $ ] days.   it proves against the thesis of the existence of strong positive fluctuations of the about @xmath0-day interval in the maximum activity period of the solar cycle 16 in the northern hemisphere.   however, a similar analysis for data from the southern hemisphere indicates that there is the periodicity of about @xmath0 days in sunspot area data in the maximum activity period of the cycle 16 only.
we study the detectability of circular polarization in a stochastic gravitational wave background from various sources such as supermassive black hole binaries, cosmic strings, and inflation in the early universe with pulsar timing arrays.   we calculate generalized overlap reduction functions for the circularly polarized stochastic gravitational wave background.   we find that the circular polarization can not be detected for an isotropic background. however, there is a chance to observe the circular polarization for an anisotropic gravitational wave background.   we also show how to separate polarized gravitational waves from unpolarized gravitational waves.
starting from the wkb approximation, a new barrier penetration formula is proposed for potential barriers containing a long - range coulomb interaction.   this formula is especially proper for the barrier penetration with penetration energy much lower than the coulomb barrier.   the penetrabilities calculated from the new formula agree well with the results from the wkb method. as a first attempt,   this new formula is used to evaluate @xmath0 decay half - lives of atomic nuclei and a good agreement with the experiment is obtained.
we study a novel class of numerical integrators, the adapted nested force - gradient schemes, used within the molecular dynamics step of the hybrid monte carlo ( hmc ) algorithm.   we test these methods in the schwinger model on the lattice, a well known benchmark problem.   we derive the analytical basis of nested force - gradient type methods and demonstrate the advantage of the proposed approach, namely reduced computational costs compared with other numerical integration schemes in hmc.
new methods for obtaining functional equations for feynman integrals are presented.   application of these methods for finding functional equations for various one- and two- loop integrals described in detail.   it is shown that with the aid of functional equations feynman integrals in general kinematics can be expressed in terms of simpler integrals.   pacs numbers : 02.30.gp, 02.30.ks, 12.20.ds, 12.38.bx + keywords : feynman integrals, functional equations     +    derivation of functional equations for feynman integrals + from algebraic relations   +    * o.v.   tarasov * +   ii.   institut fr theoretische physik, universitt hamburg, + luruper chaussee 149, 22761 hamburg, germany + and + joint institute for nuclear research, + 141980 dubna, russian federation + : otarasov@jinr.ru +
in the hierarchical search for periodic sources of gravitational waves, the candidate selection, in the incoherent step, can be performed with hough transform procedures. in this paper   we analyze the problem of sensitivity loss due to discretization of the parameters space vs computing cost, comparing the properties of the sky hough procedure with those of a new frequency hough, which is based on a transformation from the _ time - observed frequency _ plane to the _ source frequency - spin down _ plane.   results on simulated peakmaps suggest various advantages in favor of the use of the frequency hough. the ones which show up to really make the difference are 1 ) the possibility to enhance the frequency resolution without relevantly affecting the computing cost.   this reduces the digitization effects ; 2 ) the excess of candidates due to local disturbances in some places of the sky map.   they do not affect the new analysis because each map is constructed for only one position in the sky.   + pacs.   numbers : 04.80nn,07.05kf,97.60jd
i summarize what we have learned about the nature of stars that ultimately explode as core - collapse supernovae from the examination of images taken prior to the explosion. by registering pre - supernova and post - supernova images, usually taken at high resolution using either space - based optical detectors, or ground - based infrared detectors equipped with laser guide star adaptive optics systems, nearly three dozen core - collapse supernovae   have now had the properties of their progenitor stars either directly measured or ( more commonly ) constrained by establishing upper limits on their luminosities.   these studies enable direct comparison with stellar evolution models that, in turn, permit estimates of the progenitor stars physical characteristics to be made.   i review progenitor characteristics ( or constraints ) inferred from this work for each of the major core - collapse supernova types ( ii - plateau, ii - linear, iib, iin, ib / c ), with a particular focus on the analytical techniques used and the processes through which conclusions have been drawn.   brief discussion of a few individual events is also provided, including sn 2005gl, a type iin supernova that is shown to have had an extremely luminous  and thus very massive  progenitor that exploded shortly after a violent, luminous blue variable - like eruption phase, contrary to standard theoretical predictions.
we present a phenomenological study of the single - transverse spin asymmetry in azimuthal correlations of two jets produced nearly `` back - to - back '' in @xmath0 collisions at rhic.   we properly take into account the initial- and final - state interactions of partons that can generate this asymmetry in qcd hard - scattering. using distribution functions fitted to the existing single - spin data, we make predictions for various weighted single - spin asymmetries in dijet correlations that are now readily testable at rhic.
kingman s coalescent is a random tree that arises from classical population genetic models such as the moran model.   the individuals alive in these models correspond to the leaves in the tree and the following two laws of large numbers concerning the structure of the tree - top are well - known : ( i ) the ( shortest ) distance, denoted by @xmath0, from the tree - top to the level when there are @xmath1 lines in the tree satisfies @xmath2 almost surely ; ( ii ) at time @xmath0, the population is naturally partitioned in exactly @xmath1 families where individuals belong to the same family if they have a common ancestor at time @xmath0 in the past. if @xmath3 denotes the size of the @xmath4th family, then @xmath5 almost surely. for both laws of large numbers   we prove corresponding large deviations results. for ( i ), the rate of the large deviations is @xmath1 and we can give the rate function explicitly. for ( ii ), the rate is @xmath1 for downwards deviations and @xmath6 for upwards deviations. for both cases   we give the exact rate function.   =     =    =     =
we discuss several novel types of multi - component ( temporal and spatial ) envelope solitary waves that appear in fiber and waveguide nonlinear optics.   in particular, we describe multi - channel solitary waves in bit - parallel - wavelength fiber transmission systems for high performance computer networks, multi - colour parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons due to quasi - phase - matching in fibonacci optical superlattices.    2
strong subadditivity inequality for a three - particle composite system is an important inequality in quantum information theory which can be studied via a four - particle entangled state.   we use two three - level atoms in @xmath0 configuration interacting with a two - mode cavity and the raman adiabatic passage technique for the production of the four - particle entangled state. using this four - particle entanglement  , we study for the first time various aspects of the strong subadditivity inequality.
evolutionary tracks and pulsational analysis of models with masses of 13 - 18 @xmath0 are presented.   we address two important questions. the first one deals with one of the most unresolved problems in astrophysics, i.e., the existence of a blue loop after core helium ignition ; the so called `` to loop or not to loop '' problem.   we show that inward overshooting from the outer convective zone in the red giant phase is prerequisite for the development of the blue loop.   our second question concerns pulsational instability of models in the core helium burning phase.   we present for the first time that models on the blue loop can have unstable modes driven by the @xmath1 mechanism operating in the @xmath2bump.   contrary to post - main sequence models in the shell hydrogen burning phases, pulsational instability of the blue loop models depends mainly on effective temperature and metallicity is of secondary importance.   finally, we try to interpret the oscillation spectrum of the blue supergiant hd 163899, the only member of the spbsg class, and to get some clue on the evolutionary status of the star.       stars : early - type  stars : supergiants  stars : oscillations
we consider one - dimensional mixtures of an atomic bose - einstein condensate ( bec ) and tonks - giradeau ( tg ) gas. the mixture is modeled by a coupled system of the gross - pitaevskii equation for the bec and the quintic nonlinear schrdinger equation for the tg component.   an immiscibility condition for the binary system is derived in a general form. under this condition,   three types of bec - tg interfaces are considered : domain walls ( dws ) separating the two components ; bubble - drops ( bds ), in the form of a drop of one component immersed into the other ( bds may be considered as bound states of two dws ) ; and bound states of bright and dark solitons ( bdss ).   the same model applies to the copropagation of two optical waves in a colloidal medium.   the results are obtained by means of systematic numerical analysis, in combination with analytical thomas - fermi approximations ( tfas ). using both methods, families of dw states   are produced in a generic form.   bd complexes exist solely in the form of a tg drop embedded into the bec background. on the contrary,   bdss exist as bound states of tg bright and bec dark components, and vice versa.
primordial black hole ( pbh ) abundance limits constrain the primordial power spectrum, and hence models of inflation, on scales far smaller than those probed by cosmological observations.   single field inflation models which are compatible with all cosmological data can have large enough perturbations on small scales to overproduce pbhs, and hence be excluded.   the standard formulae for the amplitude of perturbations do not hold for modes that exit the horizon close to the end of inflation however.   we use a modified flow analysis to identify models of inflation where the amplitude of perturbations on small scales is large. for these models   we then carry out a numerical evolution of the perturbations and use the pbh constraints on the power spectrum to eliminate models which overproduce pbhs.   significant pbh formation can occur in models in which inflation can continue indefinitely and is ended via a secondary mechanism.   we demonstrate that pbhs constrain these types of inflation models and show that a numerical evaluation of the power spectrum decreases the number of otherwise viable models of inflation.
sofia is a 2.5 meter airborne infrared telescope, mounted in a boeing 747sp aircraft. due to the large size of the telescope,   only a few degrees of azimuth are available at the telescope bearing.   this means the heading of the aircraft is fundamentally associated with the telescope s observation targets, and the ground track necessary to enable a given mission is highly complex and dependent on the coordinates, duration, and order of observations to be performed.   we have designed and implemented a flight management infrastructure ( fmi ) product in order to plan and execute such missions in the presence of a large number of external constraints ( e.g. restricted airspace, international boundaries, elevation limits of the telescope, aircraft performance, winds at altitude, and ambient temperatures ).   we present an overview of the fmi, including the process, constraints and basic algorithms used to plan and execute sofia missions.
we have simulated two - colour four - flavour qcd at non - zero chemical potential @xmath0 for quark number.   simulations were performed on @xmath1 and @xmath2 lattices.   clear evidence was seen for the formation of a colourless diquark condensate which breaks quark number spontaneously, for @xmath3.   the transition appears to be second order.   we have measured the spectrum of scalar and pseudoscalar bosons which shows clear evidence for the expected goldstone boson.   our results are in qualitative agreement with those from effective lagrangians for the potential goldstone excitations of this theory.
the mutual dipole - dipole interaction of atoms in a trap can affect their fluorescence.   extremely large effects were reported for double jumps between different intensity periods in experiments with two and three ba@xmath0 ions for distances in the range of about ten wave lengths of the strong transition while no effects were observed for hg@xmath0 at 15 wave lengths. in this theoretical paper   we study this question for configurations with three and four levels which model those of hg@xmath0 and ba@xmath0, respectively. for two systems in the hg@xmath0 configuration   we find cooperative effects of up to 30% for distances around one or two wave lengths, about 5% around ten wave lengths, and, for larger distances in agreement with experiments, practically none.   this is similar for two v systems.   however, for two four - level configurations, which model two ba@xmath0 ions, cooperative effects are practically absent, and this latter result is at odds with the experimental findings for ba@xmath0.
we define mutation on coloured quivers associated to tilting objects in higher cluster categories.   we show that this operation is compatible with the mutation operation on the tilting objects.   this gives a combinatorial approach to tilting in higher cluster categories and especially an algorithm to determine the gabriel quivers of tilting objects in such categories.    proposition corollary theorem remark definition example
we compute the one - loop corrections to the @xmath0 vertex in the @xmath1 symmetric minimal supersymmetric extension of the standard model. we find that the predicted value of @xmath2 is consistent with experiment if the mass of the lighter top squark is no more than 180 gev.   furthermore, other data combines to place a lower bound of 88 gev on the mass of the light top squark.   a top squark in this mass range should be accessible to searches by experiments at fnal and lep.   * @xmath0 in @xmath1 symmetric supersymmetry * 3em elizabeth h. simmons & yumian su 2em _ dept. of physics, boston university, + 590 commonwealth ave.,   boston, ma 02215 _   3em 3em    pacs : 12.60.jv, 13.38.dg, 14.80.ly    6em
multiplication is one of the most important operation in computer arithmetic.   many integer operations such as squaring, division and computing reciprocal require same order of time as multiplication whereas some other operations such as computing gcd and residue operation require at most a factor of @xmath0 time more than multiplication. we propose an integer multiplication algorithm using nikhilam method of vedic mathematics which can be used to multiply two binary numbers efficiently.   integer multiplication, algorithm, computer arithmetic, vedic mathematics, computation
we present new equilibrium component distribution functions that depend on three analytic integrals in a stckel potential, and that can be used to model stellar discs of galaxies.   these components are generalizations of two - integral ones and can thus provide thin discs in the two - integral approximation.   their most important properties are the partly analytical expression for their moments, the disc - like features of their configuration space densities ( exponential decline in the galactic plane and finite extent in the vertical direction ) and the anisotropy of their velocity dispersions.   we further show that a linear combination of such components can fit a van der kruit disc.   epsf rotate    = =    = =    = =    = =    # 1 # 1    # 1 # 1    @mathgroup@group    @mathgroup@normal@groupeurmn    @mathgroup@bold@groupeurbn    @mathgroup@group    @mathgroup@normal@groupmsamn    @mathgroup@bold@groupmsamn    = " 019    = " 016    = " 040    = " 336    = " 33e    = =    = =    = =    = =    # 1 # 1    # 1 # 1    = =    = =    = =    = =        galaxies : kinematics and dynamics  galaxies : stucture  stars : kinematics.
we analyze the dynamics of a single - level quantum dot with coulomb interaction, weakly tunnel coupled to an electronic reservoir, after it has been brought out of equilibrium, e.g. by a step - pulse potential.   we investigate the exponential decay towards the equilibrium state, which is governed by three time scales.   in addition to the charge and spin relaxation time there is a third time scale which is independent of the level position and the coulomb interaction.   this time scale emerges in the time evolution of physical quantities sensitive to two - particle processes.
mesoscopic dynamics of self - organized structures is the most important aspect in the description of complex living systems.   the belousov  zhabotinsky ( b  z ) reaction is in this respect a convenient testbed because it represents a prototype of chemical self - organization with a rich variety of emergent wave - spiral patterns. using a multi - state stochastic hotchpotch model,   we show here that the mesoscopic behaviour of the non - stirred b  z   reaction is both qualitatively and quantitatively susceptible to the description in terms of stochastic multilevel cellular automata.   this further implies that the mesoscopic dynamics of the non - stirred b  z reaction results from a delicate interplay between a ) a maximal number of available states within the elementary time lag ( i.e. a minimal time interval needed for demise of a final state ) and b ) an imprecision or uncertainty in the definition of state.   if either the number of time lags is largely different from 7 or the maximal number of available states is smaller than 20, the physicochemical conditions are inappropriate for a formation of the wave - spiral patterns.   furthermore, a white noise seems to be key for the formation of circular structures ( target patterns ) which could not be as yet systematically explained in existing models.
the hires collaboration has recently announced preliminary measurements of the energy spectrum of ultra - high energy cosmic rays ( uhecr ), as seen in monocular analyses from each of the two hires sites.   this spectrum is consistent with the existence of the gzk cutoff, as well other aspects of the energy loss processes that cause the gzk cutoff.   based on the analytic energy loss formalism of berezinsky _ et al.   _, the hires spectra favor a distribution of extragalactic sources that has a similar distribution to that of luminous matter in the universe, both in its local over - density and in its cosmological evolution.
dynamics is considered as a corollary of the space - time geometry.   evolution of a particle in the space - time is described as a chain of connected equivalent geometrical objects.   space - time geometry is determined uniquely by the world function @xmath0.   proper modification of the minkowskian world function for large space - time interval leads to wobbling of the chain, consisted of timelike straight segments. statistical description of the stochastic world chain coincides with the quantum description by means of the schrdinger equation.   proper modification of the minkowskian world function for small space - time interval may lead to appearance of a world chain, having a shape of a helix with timelike axis.   links of the chain are spacelike straight segments.   such a world chain describes a spatial evolution of a particle.   in other words, the helical world chain describes the particle rotation with superluminal velocity. the helical world chain associated with the classical dirac particle,   whose world line is a helix.   length of world chain link can not be arbitrary.   it is determined by the space - time geometry and, in particular, by the elementary length.   there exists some discrimination mechanism, which can discriminate some world chains.
specially - designed microlensing searches, some of which have been underway for several years, are sensitive to extrasolar planets orbiting the most common stars in our galaxy.   microlensing is particularly well - suited to the detection of jupiter - mass planets orbiting their parent stars at several au. since jovian analogs are thought to influence the subsequent evolution of most planetary systems, they are particularly important to study. the orbital radii and distances to the planetary systems probed by microlensing are larger than those currently studied by radial velocity techniques ; the two methods are thus complementary.   recent results from microlensing searches are discussed, including constraints on jovian analogs orbiting typical galactic stars.   benefits and drawbacks of the technique for the characterization of planetary systems, and future prospects are briefly reviewed.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
masers found in massive star - forming regions can be located precisely in six - dimensional phase space and therefore serve as a tool for studying milky way dynamics.   the non - random orbital phases at which the masers are found and the sparseness of current samples require modeling. here we model the phase - space distribution function of 18 precisely measured galactic masers, permitting a mean velocity offset and a general velocity dispersion tensor relative to their local standards of rest, and accounting for different pieces of prior information. with priors only on the sun   s distance from the galactic center and on its motion with respect to the local standard of rest, the maser data provide a weak constraint on the circular velocity at the sun of @xmath0 km s@xmath1. including prior information on the proper motion of sgr a@xmath2 leads to @xmath3 km s@xmath1.   we do not confirm the value of @xmath4 km s@xmath1 found in more restrictive models.   this analysis shows that there is no conflict between recent determinations of @xmath5 from galactic center analyses, orbital fitting of the gd-1 stellar stream, and the kinematics of galactic masers ; a combined estimate is @xmath6 km s@xmath1.   apart from the dynamical parameters, we find that masers tend to occur at post - apocenter, circular - velocity - lagging phases of their orbits.
we report on a high - statistics measurement of the most basic double pionic fusion reaction @xmath0 over the energy region of the @xmath1 resonance by use of a polarized deuteron beam and observing the double fusion reaction in the quasifree scattering mode.   the measurements were performed with the wasa detector setup at cosy.   the data reveal substantial analyzing powers and confirm conclusions about the @xmath2 resonance obtained from unpolarized measurements.   we also confirm the previous unpolarized data obtained under complementary kinematic conditions.
using hst and the wfpc2 we have acquired very deep v- and i - band photometry of stars in ngc 2420 and ngc 2477 to study cluster luminosity functions at approximately solar metallicity.   we have determined these cluster luminosity functions down to @xmath0 = 10.5 ( 0.2 m@xmath1 ) and find that the luminosity function of ngc 2420 turns over at @xmath0 @xmath2 9.0, and possibly stops altogether by @xmath0 @xmath2 9.5.   the luminosity function of ngc 2477 may flatten at @xmath0 @xmath3 9.5.   we compare our open cluster luminosity functions to the solar neighborhood field star luminosity function of kroupa, tout & gilmore ( 1993 ) and the four published hst globular cluster luminosity functions : @xmath4 cen ( elson _ et al. _   1995 ), 47 tuc ( de marchi & paresce 1995b ), m 15 ( de marchi & paresce 1995a ), and ngc 6397 ( paresce, de marchi & romaniello 1995 ).   we find a smooth relation between the location of the luminosity function turn - over and the metallicity for all these low mass star samples which matches the expected @xmath0 versus  trend for a model star of @xmath2 0.27 m@xmath1 ( saumon 1995 ; alexander _ et al. _   1996 ).   we interpret this smooth and systematic behavior in the cluster luminosity functions as strong evidence in favor of an invariant initial mass function and a metallicity - dependent mass - luminosity relation.
we describe the design and performance of the medium resolution spectrometer ( mrs ) for the jwst - miri instrument.   the mrs incorporates four coaxial spectral channels in a compact opto - mechanical layout that generates spectral images over fields of view up to 7.7 x 7.7 arcseconds in extent and at spectral resolving powers ranging from 1,300 to 3,700.   each channel includes an all - reflective integral field unit ( ifu ) : an ` image slicer'that reformats the input field for presentation to a grating spectrometer.   two 1024 x 1024 focal plane arrays record the output spectral images with an instantaneous spectral coverage of approximately one third of the full wavelength range of each channel.   the full 5 to 28.5 @xmath0 m spectrum is then obtained by making three exposures using gratings and pass - band - determining filters that are selected using just two three - position mechanisms.   the expected on - orbit optical performance is presented, based on testing of the miri flight model and including spectral and spatial coverage and resolution.   the point spread function of the reconstructed images is shown to be diffraction limited and the optical transmission is shown to be consistent with the design expectations.
we demonstrate that 4-body real space jastrow factors are, with the right type of jastrow basis function, capable of performing successful wave function stenciling to remove unwanted ionic terms from an overabundant fermionic reference without unduly modifying the remaining components.   in addition to greatly improving size consistency ( restoring it exactly in the case of a geminal power ), real - space wave function stenciling is, unlike its hilbert space predecessors, immediately compatible with diffusion monte carlo, allowing it to be used in the pursuit of compact, strongly correlated trial functions with reliable nodal surfaces.   we demonstrate the efficacy of this approach in the context of a double bond dissociation by using it to extract a qualitatively correct nodal surface despite being paired with a restricted slater determinant, that, due to ionic term errors, produces a ground state with a qualitatively incorrect nodal surface when used in the absence of the jastrow.
we show how one can measure anomalous @xmath0- and @xmath1-couplings with minimal statistical error using integrated observables, without having to assume that the anomalous couplings are small.   we propose a parametrisation of these couplings which is well suited for the extraction of both single and many parameters, and which leads to a very simple form of the integrated cross section, from which additional information on the couplings can be obtained.   hd   thep9703 + cpth   s4940197    anomalous three gauge boson +   m. diehl + _ department of applied mathematics and theoretical physics + silver street, cambridge cb3 9ew, great britain + present address : + centre de physique thorique + ecole polytechnique, f-91128 palaiseau cedex, france _ + and + o. nachtmann + _ institut fr theoretische physik + philosophenweg 16, d-69120 heidelberg, germany _
we present four - dimensional gauge theories that describe physics on five - dimensional curved ( warped ) backgrounds, which includes bulk fields with various spins ( vectors, spinors, and scalars ).   field theory on the ads@xmath0 geometry is examined as a simple example of our formulation.   various properties of bulk fields on this background, e.g.,  the mass spectrum and field localization behavior, can be achieved within a fully four - dimensional framework. moreover, that gives a localization mechanism for massless vector fields.   we also consider supersymmetric cases, and show in particular that the conditions on bulk masses imposed by supersymmetry on warped backgrounds are derived from a four - dimensional supersymmetric theory on the flat background. as a phenomenological application,   models are shown to generate hierarchical yukawa couplings.   finally, we discuss possible underlying mechanisms which dynamically realize the required couplings to generate curved geometries.   kuns-1790 + hupd-0202 + ut-02 - 35 + tu-658    * field localization in warped gauge theories *    hiroyuki  abe, tatsuo  kobayashi, nobuhito  maru and koichi  yoshioka    @xmath1_department of physics, kyoto university, kyoto 606 - 8502, japan _ + @xmath2_department of physics, hiroshima university, hiroshima 739 - 8526, japan _ + @xmath3_department of physics, university of tokyo, tokyo 113 - 0033, japan _ + @xmath4_department of physics, tohoku university, sendai 980 - 8578, japan _
recent observations show that the number of stars with very low metallicities in the dwarf spheroidal satellites of the milky way is low, despite the low average metallicities of stars in these systems.   we undertake numerical simulations of star formation and metal enrichment of dwarf galaxies in order to verify whether this result can be reproduced with `` standard '' assumptions.   the answer is likely to be negative, unless some selection bias against very low metallicity stars is present in the observations.
we present a numerical method for calculating piecewise smooth spectral functions of correlated quantum systems in the thermodynamic limit from the spectra of finite systems computed using the dynamical or correction - vector density - matrix renormalization group method.   the key idea is to consider this problem as a blind deconvolution with an unknown kernel which causes both a broadening and finite - size corrections of the spectrum. in practice  , the method reduces to a least - square optimization under non - linear constraints which enforce the positivity and piecewise smoothness of spectral functions.   the method is demonstrated on the single - particle density of states of one - dimensional paramagnetic mott insulators represented by the half - filled hubbard model on an open chain.   our results confirm that the density of states has a step - like shape but no square - root singularity at the spectrum onset.
complex potential and non - hermitian hopping amplitude are building blocks of a non - hermitian quantum network.   appropriate configuration, such as @xmath0-symmetric distribution, can lead to a full real spectrum. to investigate the underlying mechanism of this phenomenon, we study the phase diagrams of a semi - infinite non - hermitian systems.   they consist of finite non - hermitian clusters and semi - infinite leads. based on the analysis of the solutions of the concrete systems  , it is shown that they can have full real spectra without any requirements on the symmetry and the wave function within the leads becomes unidirectional plane waves at the exceptional point.   this universal dynamical behavior is demonstrated as the persistent emission and reflectionless absorption of wave packets in the typical non - hermitian systems containing the complex on - site potentials and non - hermitian hopping amplitudes.
a derivation is given for the vogel - fulcher - tammann thermal activation law for the glassy state of a bulk polymer.   our microscopic considerations involve the entropy of closed polymer molecular chains ( i.e. polymer closed strings ). for thin film polymer glasses,   one obtains open polymer strings in that the boundary surfaces serve as possible string endpoint locations.   the vogel - fulcher - tammann thermal activation law thereby holds true for a bulk polymer glass but is modified in the neighborhood of the boundaries of thin film polymers.
we present a theoretical study of an ensemble of x - like 4-level atoms placed in an optical cavity driven by a linearly polarized field.   we show that the self - rotation ( sr ) process leads to polarization switching ( ps ). below the ps threshold, both the mean field mode and the orthogonal vacuum mode   are squeezed.   we provide a simple analysis of the phenomena responsible for the squeezing and trace the origin of vacuum squeezing not to sr, but to crossed kerr effect induced by the mean field.   last, we show that this vacuum squeezing can be interpreted as _ polarization squeezing_.
this paper gives a summary of the author s works concerning the emergent general relativity in a particular class of tensor models, which possess gaussian classical solutions.   in general, a classical solution in a tensor model may be physically regarded as a background space, and small fluctuations about the solution as emergent fields on the space.   the numerical analyses of the tensor models possessing gaussian classical background solutions have shown that the low - lying long - wavelength fluctuations around the backgrounds are in one - to - one correspondence with the geometric fluctuations on flat spaces in the general relativity.   it has also been shown that part of the orthogonal symmetry of the tensor model spontaneously broken by the backgrounds can be identified with the local translation symmetry of the general relativity.   thus the tensor model provides an interesting model of simultaneous emergence of space, the general relativity, and its local gauge symmetry of translation.   = 17.5pt plus 0.2pt minus 0.1pt    # 1( )
it is a known fact that a quintessence model with @xmath0 fits the publicly available super nova ( sn ) type ia data better than a model with cosmological constant or @xmath1.   two types of models have this property : scalar fields with unconventional kinetic term and models with cosmological constant and a slowly decaying cold dark matter ( cdm ). in this work   we investigate the possibility of replacing the cosmological constant in the latter models with gradual condensation of a scalar field produced during the decay of the cdm and present some preliminary results.   the advantage of this class of models to the ordinary quintessence is that the evolution of the dark energy and cdm are correlated and cosmological coincidence problem is solved or at least reduced to the fine tuning of the coupling between decaying cdm and quintessence field i.e the hierarchy problem.   here we show that for part of the parameter space these models are consistent with present estimation of cosmological parameters.    *   quintessence from a decaying dark matter + *    _ houri ziaeepour + mullard space science laboratory, + holmbury st.   mary, dorking, surrey rh5 6nt, uk. +   email : hz@mssl.ucl.ac.uk_
in this work, we have used an effective field theory ( eft ) framework based on heavy quark spin ( hqss ), heavy flavour ( hfs ) and heavy antiquark - diquark symmetries ( hads ). using a standard lagrangian for the heavy meson - heavy antimeson system, we fit the counter - terms of the model to predict some promising experimental data that can be interpreted as heavy meson - heavy antimeson molecules, that is, the @xmath0 and the @xmath1.   next, and, taking advantage of hads, we use the same lagrangian to explore the consequences for heavy meson - doubly heavy baryon molecules, which can also be interpreted as triply heavy pentaquarks.
we introduce new methods for robust high - precision photometry from well - sampled images of a non - crowded field with a strongly varying point - spread function. for this work, we used archival imaging data of the open cluster m37 taken by mmt 6.5 m telescope.   we find that the archival light curves from the original image subtraction procedure exhibit many unusual outliers, and more than 20% of data get rejected by the simple filtering algorithm adopted by early analysis. in order to achieve better photometric precisions and also to utilize all available data, the entire imaging database was re - analyzed with our time - series photometry technique ( multi - aperture indexing photometry ) and a set of sophisticated calibration procedures.   the merit of this approach is as follows : we find an optimal aperture for each star with a maximum signal - to - noise ratio, and also treat peculiar situations where photometry returns misleading information with more optimal photometric index.   we also adopt photometric de - trending based on a hierarchical clustering method, which is a very useful tool in removing systematics from light curves.   our method removes systematic variations that are shared by light curves of nearby stars, while true variabilities are preserved.   consequently, our method utilizes nearly 100% of available data and reduce the rms scatter several times smaller than archival light curves for brighter stars.   this new data set gives a rare opportunity to explore different types of variability of short ( @xmath0minutes ) and long ( @xmath01 month ) time scales in open cluster stars.
truncated fourier, gauss, kummer and exponential sums can be used to factorize numbers : for a factor these sums equal unity in absolute value, whereas they nearly vanish for any other number.   we show how this factorization algorithm can emerge from superpositions of classical light waves and we present a number of simple implementations in optics.
statistical learning theory chiefly studies restricted hypothesis classes, particularly those with finite vapnik - chervonenkis ( vc ) dimension.   the fundamental quantity of interest is the sample complexity : the number of samples required to learn to a specified level of accuracy.   here we consider learning over the set of all computable labeling functions.   since the vc - dimension is infinite and a priori ( uniform ) bounds on the number of samples are impossible, we let the learning algorithm decide when it has seen sufficient samples to have learned. we first show that learning in this setting is indeed possible, and develop a learning algorithm.   we then show, however, that bounding sample complexity independently of the distribution is impossible.   notably, this impossibility is entirely due to the requirement that the learning algorithm be computable, and not due to the statistical nature of the problem.
electroweak corrections to longitudinal gauge and higgs boson scattering amplitudes are calculated. due to sudakov   double logarithms, the effect is a suppression of amplitude that grows rapidly with increasing center of mass energy leading to significant reduction of cross sections compared to tree level results.   for example, the suppression factor for the cross section of @xmath0 scattering due to these corrections varies from @xmath1 at the center of mass energy of @xmath2 to a factor of @xmath3 at the center of mass energy of @xmath4.   the modification of sm unitarity bound due to these corrections is obtained.
we performed single point  @xmath0p@xmath1@xmath0p@xmath2 and co @xmath3=43 observations toward three t tauri stars, dm tau, lkca 15, and tw hya, using the atacama large millimeter / submillimeter array ( alma ) band 8 qualification model receiver installed on the atacama submillimeter telescope experiment ( aste ).   two protostars in the taurus l1551 region, l1551 irs 5 and hl tau, were also observed.   we successfully detected  emission from the protoplanetary disk around dm tau as well as the protostellar targets.   the spectral profile of the  emission from the protoplanetary disk is marginally single - peaked, suggesting that atomic carbon ( c ) extends toward the outermost disk.   the detected  emission is optically thin and the column densities of c are estimated to be @xmath4 @xmath5 and @xmath6 @xmath5 for the t tauri star targets and the protostars, respectively.   we found a clear difference in the total mass ratio of c to dust, @xmath7(c)/@xmath7(dust ), between the t tauri stars and protostellar targets ; the @xmath7(c)/@xmath7(dust ) ratio of the t tauri stars is one order of magnitude smaller than that of the protostars.   the decrease of the estimated @xmath7(c)/@xmath7(dust ) ratios for the disk sources is consistent with a theoretical prediction that the atomic c can survive only in the near surface layer of the disk and c@xmath8/c / co transition occurs deeper into the disk mid
to study the dynamics of chemical processes, we often adopt rate equations to observe the change in chemical concentrations.   however, when the number of the molecules is small, the fluctuations can not be neglected.   we often study the effects of fluctuations with the help of stochastic differential equations.   chemicals are composed of molecules on a microscopic level. in principle  , the number of molecules must be an integer, which must only change discretely.   however, in analysis using stochastic differential equations, the fluctuations are regarded as continuous changes  . this approximation can only be valid if applied to fluctuations that involve a sufficiently large number of molecules. in the case of extremely rare chemical species,   the actual discreteness of the molecules may critically affect the dynamics of the system.    to elucidate the effects of the discreteness, we study an autocatalytic system consisting of several interacting chemical species with a small number of molecules through stochastic particle simulations.   we found novel states, which were characterized as an extinction of molecule species, due to the discrete nature of the molecules.   we also observed a strong dependence of the chemical concentrations on the size of the system, which was caused by transitions to the novel states.
we report the discovery of 42 white dwarfs in the original _ kepler _ mission field, including nine new confirmed pulsating hydrogen - atmosphere white dwarfs ( zzceti stars ).   guided by the _ kepler_-int survey ( kis ), we selected white dwarf candidates on the basis of their @xmath0, @xmath1, and @xmath2 photometric colours.   we followed up these candidates with high - signal - to - noise optical spectroscopy from the 4.2-m william herschel telescope. using ground - based, time - series photometry  , we put our sample of new spectroscopically characterized white dwarfs in the context of the empirical zzceti instability strip. prior to our search  , only two pulsating white dwarfs had been observed by _   kepler_. ultimately, four of our new zzcetis were observed from space.   these rich datasets are helping initiate a rapid advancement in the asteroseismic investigation of pulsating white dwarfs, which continues with the extended _ kepler _ mission, _ k2_.        asteroseismology, surveys, stars : white dwarfs, oscillations
we present a combined analysis of the low - mass initial mass function ( imf ) for seven star - forming regions.   we first demonstrate that the ratios of stars to brown dwarfs are consistent with a single underlying imf. by assuming that the underlying imf is the same for all seven clusters and by combining the ratio of stars to brown dwarfs from each cluster we constrain the shape of the brown dwarf imf and find it to be consistent with a lognormal imf.   this provides the strongest constraint yet that the substellar imf turns over ( @xmath0, @xmath1 ).
the robust effect of curvature on spin polarization is reported in a three - terminal bridge system where the bridging material is subjected to rashba spin - orbit interaction.   the results are examined considering two different geometric configurations, ring- and linear - like, of the material which is coupled to one input and two output leads.   our results exhibit absolute zero spin polarization for the linear sample, while finite polarization is obtained in output leads for the ring - like sample.
we investigate system - environment correlations based on the exact dynamics of a qubit and its environment in the framework of pure decoherence ( phase damping ).   we focus on the relation of decoherence and the build - up of system - reservoir entanglement for an arbitrary ( possibly mixed ) initial qubit state. in the commonly employed regime   where the qubit dynamics can be described by a markov master equation of lindblad type, we find that for almost all qubit initial states inside the bloch sphere, decoherence is complete while the total state is still separable - no entanglement is involved. in general, both `` separable '' and `` entangling '' decoherence occurs, depending on temperature and initial qubit state.   moreover, we find situations where classical and quantum correlations periodically alternate as a function of time in the regime of low temperatures.
advances in micro deformable mirror ( dm ) technologies such as mems, have stimulated interest in the characteristics of systems that include a high stroke mirror in series with a high actuator count mirror.   this arrangement is referred to as a woofer - tweeter system. in certain situations   it may be desirable or necessary to operate the woofer dm in open - loop.   we present a simple method for controlling a woofer dm in open loop provided the device behaves in an approximately linear fashion.   we have tested a mirror that we believe meets our criterion, the alpao dm52 mirror. using our open - loop method we fit several test kolmogorov wavefronts with the mirror and   have achieved an accuracy of approximately 25 @xmath0 @xmath1 surface deviation over the whole clear aperture, and 20 @xmath0 @xmath1 over 90% of the aperture.   we have also flattened the mirror in open loop to approximately 11 @xmath0 @xmath1 residual.
gamma - ray bursts ( grbs ) are cosmological explosions which carry valuable information from the distant past of the expanding universe.   one of the greatest discoveries in modern cosmology is the finding of the accelerated expansion of the universe using type ia supernovae ( sn ia ) as standard candles.   however, due to the interstellar extinction sn ia can be seen only up to a redshift @xmath0.   grbs are considered as the potential alternative to push this limit to as high as @xmath1, a redshift regime corresponding to an epoch when the universe just started to form the first structures. there   exist several correlations between the energy and an observable of a grb which can be used to derive luminosity distance. in recent works  , we have studied spectral evolution within the individual pulses and obtained such correlations within the pulses. here   we summarize our results of the pulse - wise grb correlation study.   it is worth mentioning that all grb correlations are still empirical, and we can not use them in cosmology unless we understand the basic physics of grbs. to this end, we need to investigate the prompt emission spectrum which is so far generally described by the empirical band function.   we shall discuss our current understanding of the radiation process particularly the finding of two blackbodies and a powerlaw ( the 2bbpl model ) as the generic spectral model and its implication.   this is a work in progress and we expect to obtain the most fundamental grb correlation based on our improved spectral model.
rapid uniform rotation of newborn neutron stars ( protoneutron stars ) is studied for a range of internal temperatures and entropies per baryon predicted by the existing numerical simulations.   calculations are performed using general relativistic equations of hydrostatic equilibrium of rotating, axially symmetric stars.   stability of rotating configurations with respect to mass shedding and the axially symmetric perturbations is studied.   numerical calculations are performed for a realistic dense matter equation of state, under various assumptions concerning neutron star interior ( large trapped lepton number, no trapped lepton number, isentropic, isothermal ). for configurations with baryon mass well below the maximum one for the non - rotating models, the mass shedding limit depends quite sensitively on the position of the `` neutrinosphere '' ( which has a deformed, spheroidal shape ) ; this dependence weakens with increasing baryon mass.   the absolute upper limit on rotation frequency is, to a good approximation, obtained for the maximum baryon mass of rotating configurations.   empirical formula for the maximum rotation frequency of uniformly rotating protoneutron stars is shown to be quite precise ; it actually coincides with that used for cold neutron stars.   evolutionary sequences at fixed baryon mass and angular momentum, which correspond to evolution of protoneutron stars into cold neutron stars are studied, and resulting constraints on the maximum rotation frequency of solitary pulsars are discussed.
starting from the pioneering work of g. s. agarwal , we present a unified derivation of a number of modified fluctuation - dissipation relations ( mfdr ) that relate response to small perturbations around non - equilibrium steady states to steady - state correlations. using this formalism   we show the equivalence of velocity forms of mfdr derived using _   continuum _   langevin and _ discrete _ master equation dynamics.   the resulting additive correction to the einstein relation is exemplified using a flashing ratchet model of molecular motors.   # 1
the polarization measure is the probability that among 3 individuals chosen at random from a finite population exactly 2 come from the same class.   this index is maximum at the midpoints of the edges of the probability simplex.   we compute the gradient flow of this index that is the differential equation whose solutions are the curves of steepest ascent.   tools from information geometry are extensively used. in a time series  , a comparison of the estimated velocity of variation with the direction of the gradient field should be a better index than the simple variation of the index.
in this article, we develop a general method for constructing wavelets @xmath0 on irregular lattices of the form @xmath1, and with an arbitrary countable family of invertible @xmath2 matrices @xmath3 that do not necessarily have a group structure. this wavelet construction is a particular case of general atomic frame decompositions of @xmath4 developed in this article, that allow other time frequency decompositions such as non - harmonic gabor frames with non - uniform covering of the euclidean space @xmath5.   possible applications include image and video compression, speech coding, image and digital data transmission, image analysis, estimations and detection, and seismology.
we assess the probable redshift ( @xmath0 ) for full reionization of the intergalactic medium ( igm ) using a prescription for the co - moving star - formation - rate ( sfr ) density ( @xmath1 ) required to maintain photoionization against recombination.   our newly developed on - line reionization simulator allows users to assess the required sfr and ionization histories, using a variety of assumptions for galactic and stellar populations, igm clumping factor and temperature, and lyc escape fraction.   the decline in high - redshift galaxy candidates and ly@xmath2  emitters at @xmath3 suggests a rising neutral fraction, with reionization at @xmath4 increasingly difficult owing to increased recombination rates and constraints from the ionizing background and lyc mean free path.   the required rate is @xmath5 ^ 3   ( c_h/3)(0.2/f_{\rm esc } ) t_4^{-0.845}$ ] scaled to fiducial values of clumping factor @xmath6, escape fraction @xmath7, electron temperature @xmath8  k, and low - metallicity initial mass functions ( imf ) and stellar atmospheres.   our hydrodynamical + n - body simulations find a mean clumping factor @xmath9^{-1.1}$ ] in the photoionized, photoheated filaments at @xmath10.   the critical sfr could be reduced by increasing the minimum stellar mass, invoking a top - heavy imf, or systematically increasing @xmath11 at high @xmath12.   the cmb optical depth, @xmath13, could be explained by full reionization, producing @xmath14 back to @xmath15, augmented by @xmath16 in a partially ionized igm
dimensionality reduction methods are very common in the field of high dimensional data analysis  . typically, algorithms for dimensionality reduction are computationally expensive.   therefore, their applications for the analysis of massive amounts of data are impractical.   for example, repeated computations due to accumulated data are computationally prohibitive. in this paper, an out - of - sample extension scheme, which is used as a complementary method for dimensionality reduction, is presented.   we describe an algorithm which performs an out - of - sample extension to newly - arrived data points.   unlike other extension algorithms such as nystrm algorithm, the proposed algorithm uses the intrinsic geometry of the data and properties for dimensionality reduction map.   we prove that the error of the proposed algorithm is bounded. additionally to the out - of - sample extension,   the algorithm provides a degree of the abnormality of any newly - arrived data point.
the composite operator formalism is applied to qcd at finite temperature to calculate the masses of scalar and pseudoscalar mesons. in particular the ratio of the sigma mass to the pion mass   is an interesting measure of the degree of chiral symmetry breaking at different temperatures.   we calculate the temperature @xmath0 at which @xmath1, above which the sigma partial width into two pions vanishes.   we find @xmath2 ( where @xmath3 is the critical temperature for the chiral phase transition ), within the full effective potential given by the formalism.   we find that an expansion _ a - la _ landau of the effective potential around the critical point in the limit of small quark mass provides for a very good determination of @xmath0.   ugva - dpt 1998/09 - 1015    firenze preprint - dff - 320/09/1998
we investigate the current and noise characteristics of a double quantum dot system.   the strong correlations induced by the coulomb interaction and the pauli principle create entangled two - electron states and lead to signatures in the transport properties.   we show that the interaction parameter @xmath0, which measures the admixture of the double - occupancy contribution to the singlet state and thus the degree of entanglement, can be directly accessed through the fano factor of super - poissonian shot noise.
we describe a new paradox for ideal fluids.   it arises in the accretion of an _ ideal _ fluid onto a black hole, where, under suitable boundary conditions, the flow can violate the generalized second law of thermodynamics.   the paradox indicates that there is in fact a lower bound to the correlation length of any _ real _ fluid, the value of which is determined by the thermodynamic properties of that fluid.   we observe that the universal bound on entropy, itself suggested by the generalized second law, puts a lower bound on the correlation length of any fluid in terms of its specific entropy. with the help of a new, efficient estimate for the viscosity of liquids  , we argue that this also means that viscosity is bounded from below in a way reminiscent of the conjectured kovtun - son - starinets lower bound on the ratio of viscosity to entropy density.   we conclude that much light may be shed on the kovtun - son - starinets bound by suitable arguments based on the generalized second law.
the  nessie " nebula is a filamentary infrared dark cloud ( irdc ) with a large aspect ratio of over 150:1 ( 1.5@xmath0@xmath1 0.01@xmath0, or 80 pc @xmath1 0.5 pc at a kinematic distance of 3.1 kpc ). maps of ( 10)emission, a tracer of dense molecular gas, made with the australia telescope national facility mopra telescope, show an excellent morphological match to the mid - ir extinction. moreover, because the molecular line emission from the entire nebula has the same radial velocity to within @xmath2, the nebula is a single, coherent cloud and not the chance alignment of multiple unrelated clouds along the line of sight.   the nessie nebula contains a number of compact, dense molecular cores which have a characteristic projected spacing of @xmath3 4.5 pc along the filament.   the theory of gravitationally bound gaseous cylinders predicts the existence of such cores, which, due to the `` sausage '' or `` varicose '' fluid instability, fragment from the cylinder at a characteristic length scale.   if turbulent pressure dominates over thermal pressure in nessie, then the observed core spacing matches theoretical predictions.   we speculate that the formation of high - mass stars and massive star clusters arises from the fragmentation of filamentary irdcs caused by the `` sausage '' fluid instability that leads to the formation of massive, dense molecular cores.   the filamentary molecular gas clouds often found near high - mass star - forming regions ( e.g., orion, ngc 6334, etc. )   may represent a later stage of irdc evolution.
theoretical studies of the fractional quantum hall effect ( fqhe ) in graphene have so far focused on the plausibility and stability of the previously known fqhe states for the interaction matrix elements appropriate for graphene.   we consider fqhe for su(4 ) symmetry, as appropriate for the situation when all four spin and valley landau bands are degenerate, and predict new fqhe states that have no analog in gaas.   these result from an essential interplay between the two - fold spin and valley degeneracies at fractions of the form @xmath0, for @xmath1.   conditions are outlined for the observation of these states and quantum phase transitions between them ; the structure of these states and their excitations is also described.
we observed the spiral galaxies m@xmath051  and m@xmath083  at 20@xmath1 spatial resolution with the bolometer array _   aztec _ on the _ jcmt _ in the 1.1@xmath0 mm continuum, recovering the extended emission out to galactocentric radii of more than 12@xmath0kpc in both galaxies.   the 1.1@xmath0mm - continuum fluxes are @xmath2 and @xmath3, with associated gas masses estimated at @xmath4 and @xmath5 for m@xmath051  and m@xmath083, respectively. in the interarm regions of both galaxies the @xmath6 ( or x -   factor ) ratios exceed those in the arms by factors of @xmath7 - 2. in the inner disks of both galaxies,   the x - factor is about @xmath8. in the outer parts,   the co - dark molecular gas becomes more important.   while the spiral density wave in m@xmath051  appears to influence the interstellar medium and stars in a similar way, the bar potential in m@xmath083   influences the interstellar medium and the stars differently.   we confirm the result of @xcite that the arms merely heighten the star formation rate and the gas surface density in the same proportion.   our maps reveal a threshold gas surface density for an sfr increase by two or more orders of magnitude. in both galaxy centers,   the molecular gas depletion time is about 1@xmath0gyr climbing to 10 - 20@xmath0gyr at radii of 6 - 8@xmath0kpc.   this is consistent with an inside - out depletion of the molecular gas in the disks of spiral galaxies.       galaxies : ism
the first renormalisable quantum field theories on non - commutative space have been found recently.   we review this rapidly growing subject.    _   @xmath0laboratoire de physique thorique, bt.  210 + universit paris xi, f-91405 orsay cedex, france + e - mail : ` rivass@th.u-psud.fr ` _ + _ @xmath1ihs, le bois - marie, 35 route de chartres, f-91440 bures - sur - yvette, france + e - mail : ` vignes@ihes.fr ` _
movements of molecular motors on cytoskeletal filaments are described by directed walks on a line.   detachment from this line is allowed to occur with a small probability.   motion in the surrounding fluid is described by symmetric random walks.   effects of detachment and reattachment are calculated by an analytical solution of the master equation.   results are obtained for the fraction of bound motors, their average velocity and displacement.   enclosing the system in a finite geometry ( tube, slab ) leads to an experimentally realizable problem, that is studied in a continuum description and also numerically in a lattice simulation.   ,    and   molecular motors, random walks, lattice models, brownian motion 87.16.nn, 05.40.-a, 05.60.-k
the closed causal chains arising from backward time travel do not lead to paradoxes if they are self consistent.   this raises the question as to how physics ensures that only self - consistent loops are possible.   we show that, for one particular case at least, the condition of self consistency is ensured by the interference of quantum mechanical amplitudes associated with the loop.   if this can be applied to all loops then we have a mechanism by which inconsistent loops eliminate themselves.
the effect of an ac perturbation on the shot noise of a fractional quantum hall fluid is studied both in the weak and the strong backscattering regimes.   it is known that the zero - frequency current is linear in the bias voltage, while the noise derivative exhibits steps as a function of bias.   in contrast, at laughlin fractions, the backscattering current and the backscattering noise both exhibit evenly spaced singularities, which are reminiscent of the tunneling density of states singularities for quasiparticles.   the spacing is determined by the quasiparticle charge @xmath0 and the ratio of the dc bias with respect to the drive frequency.   photo   assisted transport can thus be considered as a probe for effective charges at such filling factors, and could be used in the study of more complicated fractions of the hall effect. a non - perturbative method for studying photo  assisted transport at @xmath1   is developed, using a refermionization procedure.
we derive the pairwise peculiar velocity distribution function of dark matter particles applying the dark matter halo approach. unlike the previous work  , we do not assume a gaussian velocity distribution function of dark matter in a single halo, but compute it self - consistently with the assumed density profile for dark matter halo.   the resulting distribution function is well approximated by an exponential distribution which is consistent with the previous observational, numerical and theoretical results.   we also compute the pairwise peculiar velocity dispersion for different density profiles, and provide a practical fitting formula.   we apply an empirical biasing scheme into our model and present prediction for pairwise peculiar velocity dispersion of _ galaxies _, and reproduce the previous results of simulations using our semi - analytical method.
we present a time - dependent solution of the maxwell equations in the einstein universe, whose electric and magnetic fields, as seen by the stationary observers, are aligned with the clifford parallels of the @xmath0-sphere @xmath1.   the conformal equivalence between minkowski s spacetime and ( a region of ) the einstein cylinder is then exploited in order to obtain a knotted, finite energy, radiating solution of the maxwell equations in flat spacetime.   we also discuss similar electromagnetic fields in expanding closed friedmann models, and compute the matter content of such configurations.
a ginzburg - landau model for the macroscopic behaviour of a shape memory alloy is proposed.   the model is one - dimensional in essence, in that we consider the effect of the martensitic phase transition in terms of a uniaxial deformation along a fixed direction and we use a scalar order parameter whose equilibrium values describe the austenitic phase and the two martensitic variants.   the model relies on a ginzburg - landau free energy defined as a function of macroscopically measurable quantities, and accounts for thermal effects ; couplings between the various relevant physical aspects are established according to thermodynamic consistency.   the theoretical model has been implemented within a finite - element framework and a number of numerical tests are presented which investigate the mechanical behaviour of the model under different conditions ; the results obtained are analysed in relation to experimental evidences available in literature.   in particular, the influence of the strain - rate and of the ambient conditions on the response of the model is highlighted.   phase field model, shape memory alloys, strain - rate sensitivity, thermo - mechanical coupling
we study analytic surfaces in 3-dimensional euclidean space containing two circular arcs through each point.   the problem of finding such surfaces traces back to the works of darboux from xixth century.   we reduce finding all such surfaces to the algebraic problem of finding all pythagorean 6-tuples of polynomials.   the reduction is based on the schicho parametrization of surfaces containing two conics through each point and a new approach using quaternionic rational parametrization.    * keywords * : darboux cyclide, circle, moebius geometry, quaternion, pythagorean n - tuple    * 2010 msc * : 51b10, 14j26, 16h05
we argue that the isham - storey exact solution to bigravity does not describe black holes because the horizon is a singular surface. however, this is not a generic property of bigravity, but a property of a particular potential.   more general potentials do accept regular black holes.   for regular black holes, we compute the total energy and thermodynamical parameters.   phase transitions occur for certain critical temperatures.   we also find a novel region on phase space describing up to 4 allowed states for a given temperature.
we have developed a stellar wind model for ob supergiants to investigate the effects of accretion from a clumpy wind on the luminosity and variability properties of high mass x   ray binaries. assuming that the clumps are confined by ram pressure of the ambient gas and exploring different distributions for their mass and radii, we computed the expected x   ray light curves in the framework of the bondi - hoyle accretion theory, modified to take into account the presence of clumps.   the resulting variability properties are found to depend not only on the assumed orbital parameters but also on the wind characteristics.   we have then applied this model to reproduce the x - ray light curves of three representative high mass x - ray binaries : two persistent supergiant systems ( vela x-1 and 4u 1700377 ) and the supergiant fast x - ray transient igr  j11215@xmath05952.   the model can reproduce well the observed light curves, but requiring in all cases an overall mass loss from the supergiant about a factor 3@xmath010 smaller than the values inferred from uv lines studies that assume a homogeneous wind.       x  ray : individuals : vela  x@xmath01/4u  1900@xmath040, 4u 1700@xmath0377, igr  j11215@xmath05952.   stars : supergiants.
we discuss constraints on the formation of multiple populations in globular clusters ( gcs ) imposed by their present - day kinematics ( velocity dispersion and anisotropy ) and spatial distribution.   we argue that the observational evidence collected so far in the outer parts of clusters is generally consistent with an enriched population forming more centrally concentrated compared to the primordial population, in agreement with all the scenarios proposed to date ( in some cases by design ), but not sufficient to favour a particular scenario.   we highlight that the differential rotation of subpopulations is a signature that may provide crucial new constraints and allow us to distinguish between various scenarios.   finally, we discuss the spatial distribution of subpopulations in the central regions of gcs and speculate that mass segregation between subpopulations may be due to a difference in their binary fraction.
flat density cores have been obtained for a limited number of clusters of galaxies by strong gravitational lensing. using a phenomenological equation of state ( eos ) describing the full - to - partial degeneracy  , we integrate the equation of hydrostatic equilibrium.   the eos is based on an assumption that the local kinetic energy of a classical particle induced by the gravity dissolves the quantum statistical degeneracy.   the density profile is uniquely determined by four parameters, the central density, @xmath0, the properties of a fermion, namely, the mass, @xmath1, and statistical weight, @xmath2, and the ratio of the total matter density and fermion density, @xmath3. as a case study, we model the column density and 2d encircled mass profiles of a1689, whose column density profile has been observationally obtained by broadhurst et al., using gravitational lensing. the column density and 2d encircled profiles at the core,   are reasonably reproduced for models with a limited range of particle properties. in the case that previously unknown fermions with spin 1/2 dominate the dark matter, the acceptable particle mass range is between 2 and 4 ev. in the case that the dark matter consists of the mixture of degenerate relic neutrinos and classical collisionless cold dark matter particles  , the mass range of neutrinos is between 1 and 2 ev, if the ratio of the two kinds of dark matter particles is fixed to its cosmic value.   both the pure fermionic dark matter models and neutrino - cdm - mixture models reproduce the observations equally well.
this paper reports positive detections of surface differential rotation on two rapidly rotating cool stars at several epochs, by using stellar surface features ( both cool spots and magnetic regions ) as tracers of the large scale latitudinal shear that distorts the convective envelope in this type of stars.   we also report definite evidence that this differential rotation is different when estimated from cool spots or magnetic regions, and that it undergoes temporal fluctuations of potentially large amplitude on a time scale of a few years.   we consider these results as further evidence that the dynamo processes operating in these stars are distributed throughout the convective zone rather than being confined at its base as in the sun. by comparing our observations with two very simple models of the differential rotation within the convective zone, we obtain evidence that the internal rotation velocity field of the stars we investigated is not like that of the sun, and may resemble that we expect for rapid rotators.   we speculate that the changes in differential rotation result from the dynamo processes ( and from the underlying magnetic cycle ) that periodically converts magnetic energy into kinetic energy and vice versa.   we emphasise that the technique outlined in this paper corresponds to the first practical method for investigating the large scale rotation velocity field within convective zones of cool active stars, and offers several advantages over asteroseismology for this particular purpose and this specific stellar class.   line : profiles  stars : activity  stars : imaging  stars : binaries  stars : magnetic fields  stars : rotation.
the possibility is considered that turbulence is described by differential equations for which uniqueness fails maximally, at least in some limit. the inviscid burgers equation, in the context of onsager s suggestion that turbulence should be described by a negative absolute temperature, is such a limit.   in this picture, the onset of turbulence coincides with the proliferation of singularities which characterizes the failure of uniqueness.   epsf    2
in the past few years, small scale anisotropy has become a primary focus in the search for source of ultra - high energy cosmic rays ( uhecrs ). the akeno giant air shower array ( agasa )   has reported the presence of clusters of event arrival directions in their highest energy data set.   the high resolution fly s eye ( hires ) has accumulated an exposure in one of its monocular eyes at energies above @xmath0  ev comparable to that of agasa. however, monocular events observed with an air fluorescence detector are characterized by highly asymmetric angular resolution.   a method is developed for measuring autocorrelation with asymmetric angular resolution.   it is concluded that hires - i observations are consistent with no autocorrelation and that the sensitivity to clustering of the hires - i detector is comparable to that of the reported agasa data set.   furthermore, we state with a 90% confidence level that no more than 13% of the observed hires - i events above @xmath0  ev could be sharing common arrival directions. however, because a measure of autocorrelation makes no assumption of the underlying astrophysical mechanism that results in clustering phenomena, we can not claim that the hires monocular analysis and the agasa analysis are inconsistent beyond a specified confidence level.    cosmic rays, anisotropy, clustering, autocorrelation, hires, agasa    98.70.sa, 95.55.vj, 96.40.pq, 13.85.tp
the thermal and chemical phases of the cool component of interstellar gas are discussed. variations with galactocentric radius and from galaxy to galaxy are mostly the result of changes in the ambient interstellar pressure and radiation field.   interstellar structure that is hierarchical or fractal in the cloudy parts and has large and connected empty regions between these clouds is probably the result of turbulence.   such structure opens up the disk to the transmission of ob star light into the halo, and it provides for a diffuse ionized component that tapers away gradually from each dense hii region.   fractal cloud structure may also produce the cloud and clump mass functions, and perhaps even the star cluster mass function.    to be published in `` the physics and chemistry of the interstellar medium, '' 3rd cologne - zermatt symposium, ed.   g. winnewisser, j. sttzki, and v. ossenkopf, aachen : shaker - verlag, 1999, in press
we use the four - dimensional @xmath0 central charge superspace to give a geometrical construction of the abelian vector - tensor multiplet consisting, under @xmath1 supersymmetry, of one vector and one linear multiplet.   we derive the component field supersymmetry and central charge transformations, and show that there is a super - lagrangian, the higher components of which are all total derivatives, allowing us to construct superfield and component actions.   pacs numbers : 11.30.pb, 11.15.-q     +
the statistical toolkit is an open source system specialized in the statistical comparison of distributions.   it addresses requirements common to different experimental domains, such as simulation validation ( e.g. comparison of experimental and simulated distributions ), regression testing in the course of the software development process, and detector performance monitoring.   various sets of statistical tests have been added to the existing collection to deal with the one sample problem ( i.e. the comparison of a data distribution to a function, including tests for normality, categorical analysis and the estimate of randomness ). improved algorithms and software design   contribute to the robustness of the results.   a simple user layer dealing with primitive data types facilitates the use of the toolkit both in standalone analyses and in large scale experiments.
renewable energy powered cognitive radio ( cr ) network has gained much attention due to its combination of the cr s spectrum efficiency and the renewable energy s greennature. in the paper  , we investigate the delay - optimal data transmission in the renewable energy aided cr networks.   specifically, a primary user ( pu ) and a secondary user ( su ) share the same frequency in an area.   the su s interference to the pu is controlled by interference - signal - ratio ( isr ) constraint, which means that the isr at the pu receiver ( rx ) should be less than a threshold. under this constraint,   the renewable energy powered su aims to minimize the average data buffer delay by scheduling the renewable allocations in each slot.   a constrained stochastic optimization problem is formulated when the randomness of the renewable arrival, the uncertainty of the su s data generation, and the variability of the fading channel are taken into account. by analyzing the formulated problem, we propose two practical algorithms that is optimal for two special scenarios. and   the two algorithms respectively give an upper and a lower bound for the general scenario.   in addition, the availability of the pu s private information at the su is discussed.   finally, numerical simulations verify the effectiveness of the proposed algorithm.
we report the discovery of an x - ray counterpart of the unidentified very high energy gamma - ray source hess  j1427608. in the sky field   coincident with hess  j1427608, an extended source was found in the 28  kev band, and was designated as suzaku  j14276051.   its x - ray radial profile has an extension of @xmath0 if approximated by a gaussian.   the spectrum was well fitted by an absorbed power - law with @xmath1, @xmath2, and the unabsorbed flux @xmath3 in the 210  kev band.   using xmm - newton archive data, we found seven point sources in the suzaku source region.   however, because their total flux and absorbing column densities are more than an order of magnitude lower than those of suzaku  j14276051, we consider that they are unrelated to the suzaku source.   thus, suzaku  j14276051 is considered to be a truly diffuse source and an x - ray counterpart of hess  j1427608.   the possible nature of hess  j1427608 is discussed based on the observational properties.
we investigate coherent backscattering of light by two harmonically trapped atoms in the light of quantitative quantum duality.   including recoil and doppler shift close to an optical resonance, we calculate the interference visibility as well as the amount of which - path information, both for zero and finite temperature.
the pixel detector is the innermost tracking device of the cms experiment at the lhc.   it is built from two independent sub devices, the pixel barrel and the end disks.   the barrel consists of three concentric layers around the beam pipe with mean radii of 4.4, 7.3 and 10.2 cm.   there are two end disks on each side of the interaction point at @xmath034.5 cm and @xmath046.5 cm + this article gives an overview of the pixel barrel detector, its mechanical support structure, electronics components, services and its expected performance.  ,   ,   ,   ,   ,   ,   ,   ,   ,   ,    cms, pixel detector, lhc 29.40.wk, 29.40.gx
the density matrix renormalization group ( dmrg ) has been extended to study quantum phase transitions on random graphs of fixed connectivity. as a relevant example  , we have analysed the random ising model in a transverse field.   if the couplings are random, the number of retained states remains reasonably low even for large sizes.   the resulting quantum spin - glass transition has been traced down for a few disorder realizations, through the careful measurement of selected observables : spatial correlations, entanglement entropy, energy gap and spin - glass susceptibility, among others.
a detailed analysis is performed of transverse momentum spectra of several identified hadrons in high energy collisions within the framework of the statistical model of hadronisation.   the effect of the decay chain following hadron generation is accurately taken into account.   the considered centre - of - mass energies range from @xmath0 10 to 30 gev in hadronic collisions ( @xmath1p, pp and kp ) and from @xmath0 15 to 45 gev in collisions.   a clear consistency is found between the temperature parameter extracted from the present analysis and that obtained from fits to average hadron multiplicities in the same collision systems.   this finding indicates that in the hadronisation, the production of different particle species and their momentum spectra are two closely related phenomenons governed by one parameter.
in this talk i discuss three related topics based on some of the recent developments in hadron and nuclear physics : one, effective field theory approach to two - nucleon systems ; two, an explanation of the flavor singlet axial charge in the proton ( i.e.,  proton spin problem " ) in terms of a cheshire cat phenomenon ; and three, the quark - hadron duality in hadronic matter at high density and  qualitons " at high density ( `` superqualitons '' ).   the principal common theme in these discussions will be the emergence of the generic feature of the cheshire cat principle.   -.7 in.25 in # 1#2#3#4 # 1 * # 2 *, # 3 ( # 4 )    # 1 # 1| # 1 | # 1    0.4 cm    * effective field theory for nuclei, * 0.2 cm    * dense matter and the cheshire cat *    1.5 cm    mannque rho    0.5 cm    _ school of physics, korea institute for advanced study, seoul 130 - 012, korea _    and    _ service de physique thorique, ce saclay, 91191 gif - sur - yvette, france _   e - mail : rho@spht.saclay.cea.fr    0.5 cm
perhaps the most compelling evidence for the role of magnetic reconnection in solar flares comes from the supra - arcade downflows that have been observed above many post - flare loop arcades.   these downflows are thought to be related to highly non - potential field lines that have reconnected and are propagating away from the current sheet.   we present new observations of supra - arcade downflows taken with the atmospheric imagining assembly ( aia ) on the _ solar dynamics observatory _ ( _ sdo _ ).   the morphology and dynamics of the downflows observed with aia provide new evidence for the role of magnetic reconnection in solar flares. with these new observations we are able to measure downflows originating at much larger heights than in previous studies.   we find, however, that the initial velocities measured here ( @xmath0144 km  s@xmath1 ) are well below the alfvn speed expected in the lower corona, and consistent with previous results.   we also find no evidence that the downflows brighten with time, as would be expected from chromospheric evaporation.   these observations suggest that simple two - dimensional models can not explain the detailed observations of solar flares.
using a metric perturbation method, we study gravitational waves from a test particle scattered by a spherically symmetric relativistic star.   we calculate the energy spectrum and the waveform of gravitational waves for axial modes.   since metric perturbations in axial modes do not couple to the matter fluid of the star, emitted waves for a normal neutron star show only one peak in the spectrum, which corresponds to the orbital frequency at the turning point, where the gravitational field is strongest.   however, for an ultracompact star ( the radius @xmath0 ), another type of resonant periodic peak appears in the spectrum.   this is just because of an excitation by a scattered particle of axial quasinormal modes, which were found by chandrasekhar and ferrari.   this excitation comes from the existence of the potential minimum inside of a star.   we also find for an ultracompact star many small periodic peaks at the frequency region beyond the maximum of the potential, which would be due to a resonance of two waves reflected by two potential barriers ( regge - wheeler type and one at the center of the star ). such resonant peaks appear neither for a normal neutron star nor for a schwarzschild black hole.   consequently, even if we analyze the energy spectrum of gravitational waves only for axial modes, it would be possible to distinguish between an ultracompact star and a normal neutron star ( or a schwarzschild black hole ).   + pacs number(s ) : 04.25.nx, 04.30.-w, 04.40.dg
most of us must have been fascinated by the eye catching displays of collectively moving animals.   schools of fish can move in a rather orderly fashion and then change direction amazingly abruptly.   there are a huge number of further examples both from the living and the non - living world for phenomena during which the many interacting, permanently moving units seem to arrive at a common behavioural pattern taking place in a short time. as a paradigm of this type of phenomena we consider the problem of how birds arrive at a decision resulting in their synchronized landing.   we introduce a simple model to interpret this process.   collective motion prior to landing is modelled using a simple self - propelled particle ( spp ) system with a new kind of boundary condition, while the tendency and the sudden propagation of the intention of landing is introduced through rules analogous to the random field ising model in an external field.   we show that our approach is capable of capturing the most relevant features of collective decision making in a system of units with a variance of individual intentions and being under an increasing level of pressure to switch states.   we find that  as a function of the few parameters of our model   the collective switching from the flying to the landing state is indeed much sharper than the distribution of the individual landing intentions.   the transition is accompanied by a number of interesting features discussed in this report.
we experimentally study the velocity scaling of granular convection which is a possible mechanism of the regolith migration on the surface of small asteroids. in order to evaluate the contribution of granular convection to the regolith migration  , the velocity of granular convection under the microgravity condition has to be revealed.   although it is hard to control the gravitational acceleration in laboratory experiments, scaling relations involving the gravitational effect can be evaluated by systematic experiments.   therefore, we perform such a systematic experiment of the vibration - induced granular convection. from the experimental data, a scaling form for the granular convective velocity is obtained.   the obtained scaling form implies that the granular convective velocity can be decomposed into two characteristic velocity components : vibrational and gravitational velocities.   in addition, the system size dependence is also scaled. according to the scaling form, the granular convective velocity @xmath0 depends on the gravitational acceleration @xmath1 as @xmath2 when the normalized vibrational acceleration is fixed.   regolith migration, granular convection, scaling analysis, gravitational acceleration.
we present and discuss isospectral quantum graphs which are not isometric.   these graphs are the analogues of the isospectral domains in @xmath0 which were introduced recently in  all based on sunada s construction of isospectral domains @xcite. after presenting some of the properties of these graphs, we discuss a few examples which support the conjecture that by counting the nodal domains of the corresponding eigenfunctions one can resolve the isospectral ambiguity.
two major advantages of the star detector - uniform azimuthal acceptance complementing extended pseudo - rapidity coverage, and the ability to identify a wide variety of the hadron species in almost all kinematic ranges - have allowed us to address successfully a set of key physics topics at rhic.   we report here selected recent results from the star experiment, including insights on system size effects on medium properties, hadronization mechanisms, and partonic energy loss from triggered and non - triggered probes. in conclusion  , we present an outlook on the star new physics program in upcoming years.
the alice detector has excellent particle identification ( pid ) capabilities in the central barrel ( @xmath0 0.9 ).   this allows identified hadron production to be measured over a wide transverse momentum ( @xmath1 ) range, using different sub - detectors and techniques : their specific energy loss ( d@xmath2/d@xmath3 ), the velocity determination via time - of - flight measurement, the cherenkov angle or their characteristic weak decay topology.   results on identified light flavour hadron production at mid - rapidity measured by alice in proton - proton collisions at @xmath4 = 13 tev are presented and compared with previous measurements performed at lower energies.   the results cover a wide range of particle species including long - lived hadrons, resonances and multi - strange baryons over the @xmath1 range from 150 mev/_c _ up to 20 gev/_c _, depending on the particle species.
erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise.   this rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink - unstable magnetic flux rope.   consistent with this interpretation, the rotation is usually found to be clockwise ( as viewed from above ) if the post - eruption arcade has right - handed helicity, but counterclockwise if it has left - handed helicity. here  , we describe two non  active - region filament events recorded with the extreme - ultraviolet imaging telescope ( eit ) on the _ solar and heliospheric observatory _ ( _ soho _ ), in which the sense of rotation appears to be opposite to that expected from the helicity of the post - event arcade. based on these observations  , we suggest that the rotation of the filament axis is in general determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. in most cases,   the surrounding field provides the main contribution to the net helicity. in the events reported here,   however, the helicity associated with the filament `` barbs '' is opposite in sign to and dominates that of the overlying arcade.
the stability, electronic and optical properties of single - walled carbon nanotubes ( cnts ) and graphene noncovalently functionalized with free - base tetraphenylporphyrin ( tpp ) molecules is addressed by density functional theory calculations, including corrections to dispersive interactions.   we study the tpp physisorption on 42 cnt species, particularly those with chiral indices ( @xmath0,@xmath1 ), where @xmath2 and @xmath3.   our results show a quite strong @xmath4-@xmath4 interaction between tpp and the cnt surface, with binding energies ranging from 1.1 to 1.8  ev, where higher energies can be associated with increasing cnt diameters.   we also find that the tpp optical absorptions would not be affected by the cnt diameter or chirality.   results for the tpp physisorption on graphene show a remarkable stability with binding energy of 3.2  ev, inducing a small redshift on the @xmath4-stacked tpp absorption bands.   the strong graphene - tpp interaction also induces a charge transfer from tpp to graphene, indicating a @xmath0-type doping mechanism without compromising the graphene structure.
in vivo calcium imaging through microscopes has enabled deep brain imaging of previously inaccessible neuronal populations within the brains of freely moving subjects.   however, microendoscopic data suffer from high levels of background fluorescence as well as an increased potential for overlapping neuronal signals.   previous methods fail in identifying neurons and demixing their temporal activity because the cellular signals are often submerged in the large fluctuating background. here   we develop an efficient method to extract cellular signals with minimal influence from the background.   we model the background with two realistic components : ( 1 ) one models the constant baseline and slow trends of each pixel, and ( 2 ) the other models the fast fluctuations from out - of - focus signals and is therefore constrained to have low spatial - frequency structure.   this decomposition avoids cellular signals being absorbed into the background term. after subtracting the background approximated with this model, we use constrained nonnegative matrix factorization ( cnmf, @xcite ) to better demix neural signals and get their denoised and deconvolved temporal activity.   we validate our method on simulated and experimental data, where it shows fast, reliable, and high quality signal extraction under a wide variety of imaging parameters.
an abelian cover is a finite morphism @xmath0 of varieties which is the quotient map for a generically faithful action of a finite abelian group @xmath1.   abelian covers with @xmath2 smooth and @xmath3 normal were studied in @xcite.    here   we study the non - normal case, assuming that @xmath3 and @xmath2 are @xmath4 varieties that have at worst normal crossings outside a subset of codimension @xmath5.   special attention is paid to the case of @xmath6-covers of surfaces, which is used in @xcite to construct explicitly compactifications of some components of the moduli space of surfaces of general type.
we present new x - ray ( _ chandra _ ) and radio ( jvla ) observations of the nearby cluster abell 3744.   it hosts two prominent radio galaxies with powers in the range critical for radio - mode feedback.   the radio emission from these galaxies terminates in buoyant tendrils reaching the cluster s outer edge, and the radio - emitting plasma clearly influences the cluster s x - ray - emitting atmosphere.   the cluster s average gas temperature, of @xmath0 kev, is high for its bolometric luminosity of 3.2 @xmath1 ergs s@xmath2, but the 100 kpc - scale cavity carved out by radio - emitting plasma shows evidence of less than 2 per cent of the excess enthalpy.   we suggest instead that a high - velocity encounter with a galaxy group is responsible for dispersing and increasing the entropy of the gas in this non - cool - core cluster.   we see no evidence for shocks, or established isobaric gas motions ( sloshing ), but there is much sub - structure associated with a dynamically active central region that encompasses the brightest radio emission.   gas heating is evident in directions perpendicular to the inferred line of encounter between the infalling group and cluster.   the radio - emitting tendrils run along boundaries between gas of different temperature, apparently lubricating the gas flows and inhibiting heat transfer.   the first stages of the encounter may have helped trigger the radio galaxies into their current phase of activity, where we see x - rays from the nuclei, jets, and hotspots.
we calculate the transmission of electrons and holes between two normal - metal electrodes ( n ), separated over a distance @xmath0 by an impurity - free superconductor ( s ) with _ d_-wave symmetry of the order parameter.   nodal lines of vanishing excitation gap form ballistic conduction channels for coupled electron - hole excitations, described by an anisotropic two - dimensional dirac equation.   we find that the transmitted electrical and thermal currents, at zero energy, both have the pseudodiffusive @xmath1 scaling characteristic of massless dirac fermions  regardless of the presence of tunnel barriers at the ns interfaces.   tunnel barriers reduce the slope of the @xmath1 scaling in the case of the electrical current, while leaving the thermal current unaffected.
we consider clean cylindrical nanostructures with an applied longitudinal static magnetic field. without coulomb interaction, the field induces, for particular values, points of degeneracy where a change of ground state takes place due to aharonov - bohm effect.   the coulomb potential introduces interaction between the electronic configurations. as a consequence,   when there is degeneracy, the ground state of the system becomes a many body state - unable to be described by a mean - field theory - and a gap is opened. to study this problem  , we propose a variational multireference wave function which goes beyond the hartree - fock approximation.   using this ansatz, in addition to the avoided crossing formation, two other effects of the electron - electron interaction are pointed out : ( i ) the long - range part of the coulomb potential tends to shift the position in magnetic field of the ( avoided ) crossing points and, ( ii ) at the points of ( near ) degeneracy, the interaction can drive the system from a singlet to a triplet state inducing new real crossing points in the ground state energy curve as function of the field.   such crossings should appear in various experiments as sudden changes in the response of the system ( magnetoconductance, magnetopolarisability,... ) when the magnetic field is tuned.
current helicity quantifies the location of twisted and sheared non - potential structures in a magnetic field.   we simulate the evolution of magnetic fields in the solar atmosphere in response to flux emergence and shearing by photospheric motions. in our global - scale simulation over many solar rotations the latitudinal distribution of current helicity develops a clear statistical pattern, matching the observed hemispheric sign at active latitudes. in agreement with observations there is significant scatter and intermixing of both signs of helicity, where we find local values of current helicity density that are much higher than those predicted by linear force - free extrapolations.   forthcoming full - disk vector magnetograms from solar dynamics observatory will provide an ideal opportunity to test our theoretical results on the evolution and distribution of current helicity, both globally and in single active regions.
this paper studies secure multiparty quantum computation ( smqc ) without nonlocal measurements.   firstly, this task is reduced to secure two - party quantum computation of nonlocal controlled - not ( nl - cnot ) gate.   then, in the passive adversaries model, the secure computation of nl - cnot is reduced to bit commitment.   thus, a smqc scheme can be constructed based on bit commitment.   this scheme does not depend on trusted third party, and is secure in the passive adversaries model.   it is also pointed out that a vulnerability exists in any secure two - party quantum computation protocol of nl - cnot gate.   quantum cryptography, secure multiparty computation, bit commitment, quantum circuit, passive adversaries
we study the critical behavior of the single - site entanglement entropy @xmath0 at the mott metal - insulator transition in infinite - dimensional hubbard model. for this model  , the entanglement between a single site and rest of the lattice can be evaluated exactly, using the dynamical mean - field theory ( dmft ). both the numerical solution using exact diagonalization and the analytical one using two - site dmft gives @xmath1 ( u - u_c)$ ], with @xmath2 the double occupancy at @xmath3 and @xmath4 being different on two sides of the transition.
we present the results of bvri photometry of two galaxies with active star formation : and.   combined color index @xmath0 was used to investigate the photometrical structure of the galaxies.   index @xmath0 is not affected by internal extinction and is sensitive to the presence of blue stars.   ring - like region with active star formation at 15 " from the center reveals itself in the @xmath0 map of.   three - arm spiral structure is well - seen on the @xmath0 map of ngc 1134.   we propose to use the combined indexes @xmath0 and similarly defined indices as a tracers of star formation activity and structure of dusty galaxies.
the normal modes of a three - dimensional yukawa plasma in an isotropic, harmonic confinement are investigated by solving the linearized cold fluid equations.   the eigenmodes are found analytically and expressed in terms of hypergeometric functions.   it is found that the mode frequencies solely depend on the dimensionless plasma parameter @xmath0, where @xmath1 is the plasma radius and @xmath2 the inverse screening length.   the eigenfrequencies increase monotonically with @xmath3 and saturate in the limit @xmath4. compared with the results in the coulomb limit  [ d. h. e. dubin, phys. rev.   lett. * 66 *, 2076 ( 1991 ) ], we find a new class of modes characterized by the number @xmath5 which determines the number of radial nodes in the perturbed potential.   these modes originate from the degenerate bulk modes of the coulomb system.   analytical formulas for the eigenfrequencies are derived for limiting cases.
we present a numerical method for the investigation of non - ergodic effects in the coulomb glass. for that,   an almost complete set of low - energy many - particle states is obtained by a new algorithm.   the dynamics of the sample is mapped to the graph formed by the relevant transitions between these states, that means by transitions with rates larger than the inverse of the duration of the measurement.   the formation of isolated clusters in the graph indicates non - ergodicity.   we analyze the connectivity of this graph in dependence on temperature, duration of measurement, degree of disorder, and dimensionality, studying how non - ergodicity is reflected in the specific heat.   g    epsf
we propose an extension of the evolutionary prisoner s dilemma cellular automata, introduced by nowak and may @xcite, in which the pressure of the environment is taken into account.   this is implemented by requiring that individuals need to collect a minimum score @xmath0, representing indispensable resources ( nutrients, energy, money, etc. ) to prosper in this environment.   so the agents, instead of evolving just by adopting the behaviour of the most successful neighbour ( who got @xmath1 ), also take into account if @xmath1 is above or below the threshold @xmath0. if @xmath2 an individual has a probability of adopting the opposite behaviour from the one used by its most successful neighbour.   this modification allows the evolution of cooperation for payoffs for which defection was the rule ( as it happens, for example, when the sucker s payoff is much worse than the punishment for mutual defection ).   we also analyse a more sophisticated version of this model in which the selective rule is supplemented with a `` win - stay, lose - shift '' criterion.   the cluster structure is analyzed and, for this more complex version we found power - law scaling for a restricted region in the parameter space.
we show that the geometry of the wilson lines, entering the operator definition of the transverse - momentum dependent parton distributions and that of the soft factor, follows from the kinematics of the underlying physical process in conjunction with the gauge invariance of the qcd lagrangian. we demonstrate our method in terms of concrete examples and determine the paths of the associated wilson lines.   the validation of the factorization theorem in our approach is postponed to future work.
the potential profile across a biased molecular junction is calculated within the framework of a simple thomas  fermi type screening model.   in particular, the relationship between this profile and the lateral molecular cross section is examined.   we find that a transition from a linear potential profile to a potential that drops mainly near the molecule - metal contacts occurs with increasing cross section width, in agreement with numerical quantum calculations.
a new class of solutions to the coupled, spherically symmetric einstein - maxwell equations for a compact material source is constructed.   some of these solutions can be made to satisfy a number of requirements for being physically relevant, including having a causal speed of sound. in the case of vanishing charge   these solutions reduce to those found by bayin and tolman.   only the latter can be considered as having physically realistic properties.
we present an algorithm that computes the multipole coefficients of the galaxy three - point correlation function ( 3pcf ) without explicitly considering triplets of galaxies. rather, centering on each galaxy in the survey, it expands the radially - binned density field in spherical harmonics and combines these to form the multipoles without ever requiring the relative angle between a pair about the central.   this approach scales with number and number density in the same way as the two - point correlation function, allowing runtimes that are comparable, and 500 times faster than a naive triplet count.   it is exact in angle and easily handles edge correction.   we demonstrate the algorithm on the lasdamas sdss - dr7 mock catalogs, computing an edge corrected 3pcf out to @xmath0 in under an hour on modest computing resources.   we expect this algorithm will render it possible to obtain the large - scale 3pcf for upcoming surveys such as euclid, lsst, and desi.   cosmology : large - scale structure of universe, methods : data analysis, statistical
we study the final architecture of planetary systems that evolve under the combined effects of planet - planet and planetesimal scattering. using n - body simulations we investigate the dynamics of marginally unstable systems of gas and ice giants both in isolation and when the planets form interior to a planetesimal belt.   the unstable isolated systems evolve under planet - planet scattering to yield an eccentricity distribution that matches that observed for extrasolar planets.   when planetesimals are included the outcome depends upon the total mass of the planets. for @xmath0   the final eccentricity distribution remains broad, whereas for @xmath1 a combination of divergent orbital evolution and recircularization of scattered planets results in a preponderance of nearly circular final orbits.   we also study the fate of marginally _   stable _ multiple planet systems in the presence of planetesimal disks, and find that for high planet masses the majority of such systems evolve into resonance.   a significant fraction lead to resonant chains that are planetary analogs of jupiter s galilean satellites.   we predict that a transition from eccentric to near - circular orbits will be observed once extrasolar planet surveys detect sub - jovian mass planets at orbital radii of @xmath2.
we investigate the superfluid behavior of a two - dimensional ( 2d ) bose gas of @xmath0rb atoms using classical field dynamics. in the experiment by r. desbuquois _   et al. _, nat  . phys.   * 8 *, 645 ( 2012 ), a 2d quasicondensate in a trap is stirred by a blue - detuned laser beam along a circular path around the trap center. here  , we study this experiment from a theoretical perspective. the heating induced by stirring increases rapidly above a velocity @xmath1, which we define as the critical velocity.   we identify the superfluid, the crossover, and the thermal regime by a finite, a sharply decreasing, and a vanishing critical velocity, respectively.   we demonstrate that the onset of heating occurs due to the creation of vortex - antivortex pairs.   a direct comparison of our numerical results to the experimental ones shows good agreement, if a systematic shift of the critical phase - space density is included.   we relate this shift to the absence of thermal equilibrium between the condensate and the thermal wings, which were used in the experiment to extract the temperature.   we expand on this observation by studying the full relaxation dynamics between the condensate and the thermal cloud.
with the renewed distribution amplitudes of @xmath0, we present a reanalysis on the semi - leptonic decay @xmath1 by use of the light - cone sum rule approach with two kinds of interpolating currents.   the form factors describing the decay process are obtained and used to predict the decay width. with the inclusion of up to twist-@xmath2 contributions   the calculations give the decay width @xmath3 for chernyak - zhitnitsky - type(cz - type ) current and @xmath4 for ioffe - type current.   the ioffe - type interpolating current is found to be better for the estimation of the decay rate from a comparison with experimental data.
starting from a microscopic model, we investigate the optical spectra of molecules in strongly - coupled organic microcavities examining how they might self - consistently adapt their coupling to light.   we consider both rotational and vibrational degrees of freedom, focusing on features which can be seen in the peak in the center of the spectrum at the bare excitonic frequency. in both cases   we find that the matter - light coupling can lead to a self - consistent change of the molecular states, with consequent temperature - dependent signatures in the absorption spectrum.   however, for typical parameters, these effects are much too weak to explain recent measurements.   we show that another mechanism which naturally arises from our model of vibrationally dressed polaritons has the right magnitude and temperature dependence to be at the origin of the observed data.
the detailed sunspot catalogues, the dpd and sdd allow to study the leading and following parts of sunspot groups separately.   we examine the equilibrium distance of the two parts, the speed of removal, the asymmetry of compactness and the area growth.   the distributions of positive and negative tilts of sunspot groups are also examined.
we present the results of differential proper - motion analyses of the egg nebula ( rafgl 2688, v1610 cyg ) based on the archived two - epoch optical data taken with the hubble space telescope.   first, we determined that the polarization characteristics of the is influenced by the higher optical depth of the central regions of the nebula ( i.e., the `` dustsphere '' of @xmath0 au radius ), causing the nebula illuminated in two steps  the direct starlight is first channeled into bipolar cavities and then scattered off to the rest of the nebula.   we then measured the amount of motion of local structures and the signature concentric arcs by determining their relative shifts over the 7.25-yr interval. based on our analysis, which does not rely on the single - scattering assumption  , we concluded that the lobes have been excavated by a linear expansion along the bipolar axis for the past @xmath1  yr, while the concentric arcs have been generated continuously and moving out radially at about 10  km  s@xmath2 for the past @xmath3  yr, and there appears to be a colatitudinally - increasing trend in the radial expansion velocity field of the concentric arcs.   there exist numerical investigations into the mass - loss modulation by the central binary system, which predict such a colatitudinally - increasing expansion velocity field in the spiral - shock trails of the mass - loss ejecta.   therefore, the egg nebula may represent a rare edge - on case of the binary - modulated circumstellar environs, corroborating the previous theoretical predictions.
we consider continuous - wave ( cw ) states and dark solitons ( dss ) in a system of two fundamental - frequency ( ff ) and one second - harmonic ( sh ) waves in a planar waveguide with the quadratic [ @xmath0 nonlinearity, the ff components being linearly coupled by resonant reflections on the bragg grating ( the same model is known to support a great variety of bright solitons ).   we demonstrate that, in contrast with the usual situation in spatial - domain @xmath1 models, cw states with the phase shift @xmath2 between the ff and sh components are modulationally _ stable _ in a broad parameter region in this system, provided that the cw wavenumber does not belong to the system s spectral gap.   stationary fundamental dss are found numerically, and are also constructed by means of a specially devised analytical approximation.   bound states of two and three dss are found too.   the fundamental dss and two - solitons bound states are _ stable _ in all the cases when the cw background is stable, which is shown by dint of calculation of the corresponding eigenvalues, and verified in direct simulations.   tilted dss are found too.   they attain a maximum contrast at a finite value of the tilt, that does not depend on the @xmath1 phase mismatch. at a maximum value of the tilt, which  grows with the mismatch, the ds merges into the cw background.   interactions between the tiltedsolitons are shown to be completely elastic.
we study the dynamics of a quench - prepared domain wall state released into a system whose unitary time evolution is dictated by the hamiltonian of the heisenberg spin-@xmath0 gapped antiferromagnetic chain.   using exact wavefunctions and their overlaps with the domain wall state allows us to describe the release dynamics to high accuracy, up to the long - time limit, for finite as well as infinite systems.   the results for the infinite system allow us to rigorously prove that the system in the gapped regime ( @xmath1 ) can not thermalize in the strict sense.
the interaction of compact objects with an infinitely extended mirror plane due to quantum fluctuations of a scalar or electromagnetic field that scatters off the objects is studied.   the mirror plane is assumed to obey either dirichlet or neumann boundary conditions or to be perfectly reflecting. using the method of images, we generalize a recently developed approach for compact objects in unbounded space @xcite to show that the casimir interaction between the objects and the mirror plane can be accurately obtained over a wide range of separations in terms of charge and current fluctuations of the objects and their images.   our general result for the interaction depends only on the scattering matrices of the compact objects.   it applies to scalar fields with arbitrary boundary conditions and to the electromagnetic field coupled to dielectric objects. for the experimentally important electromagnetic casimir interaction between a perfectly conducting sphere and a plane mirror we present the first results that apply at all separations.   we obtain both an asymptotic large distance expansion and the two lowest order correction terms to the proximity force approximation.   the asymptotic casimir - polder potential for an atom and a mirror is generalized to describe the interaction between a dielectric sphere and a mirror, involving higher order multipole polarizabilities that are important at sub - asymptotic distances.
a model of quark mass matrices from six dimensions, which is nearly democatic in nature and which is previously constructed by two of us ( pqh and ms ), is studied in detail in this manuscript.   we found that not only it fits all the six quark masses as well as the ckm matrix but also that there exists a region in the allowed parameter space of the model where the constraint on the parameter @xmath0 of the strong cp problem is satisfied.   this region itself puts a constraint on the ckm parameters @xmath1 and @xmath2. as such, through our analysis, there appears to be a deep connection between strong and weak cp in this model.   = = = = = = = = = == === = = = = = = = = = = = = = = = = ==== = = =
this paper deals with the optimal stopping problem under partial observation for piecewise - deterministic markov processes.   we first obtain a recursive formulation of the optimal filter process and derive the dynamic programming equation of the partially observed optimal stopping problem.   then, we propose a numerical method, based on the quantization of the discrete - time filter process and the inter - jump times, to approximate the value function and to compute an actual @xmath0-optimal stopping time.   we prove the convergence of the algorithms and bound the rates of convergence.   keywords : optimal stopping, partial observation, filtering, piecewise deterministic markov processes, quantization, numerical method 60g40, 60j25, 93e20, 93e25, 93e10, 60k10
light curve analysis of decay phase of nova outburst are summarized.   nova duration is determined by the strong wind mass - loss which depends only on the white dwarf mass.   fast novae correspond very massive white dwarfs and very slow novae correspond almost lower mass limit of white dwarfs.   this relation is shown in both of classical novae and recurrent novae.   light curves are theoretically reproduced for recurrent novae, u sco, v394 cra, ci aql, v2487 oph, rs oph, t crb, v745 sco and v3890 sgr, using binary model composed of a white dwarf, an irradiated accretion disk, and partly irradiated companion which is shadowed by the accretion disk. from the light curve fitting,   we conclude that most of these objects contain a very massive white dwarf close to the chandrasekhar mass limit ( 1.37 @xmath0 for u sco, v394 cra t crb and rs oph, 1.35 @xmath0 for v2487 oph, v3890 sgr and v745 sco ).   they are strong candidates of type ia sn progenitors.   population ii novae have trends of slow evolution and small expanding velocity compared with disk novae.   # 1 1.25 in.125 in.25 in
the emission from young stellar objects ( ysos ) in the mid - ir is dominated by the inner rim of their circumstellar disks.   we present an ir - monitoring survey of @xmath0 objects in the direction of the lynds 1688 ( l1688 ) star forming region over four visibility windows spanning 1.6  years using the _ spitzer _ space telescope in its warm mission phase. among all lightcurves,   57 sources are cluster members identified based on their spectral - energy distribution and x - ray emission.   almost all cluster members show significant variability. the amplitude of the variability is larger in more embedded ysos.   ten out of 57 cluster members have periodic variations in the lightcurves with periods typically between three and seven days, but even for those sources, significant variability in addition to the periodic signal can be seen.   no period is stable over 1.6  years.   non - periodic lightcurves often still show a preferred timescale of variability which is longer for more embedded sources. about half of all sources exhibit redder colors in a fainter state.   this is compatible with time - variable absorption towards the yso.   the other half becomes bluer when fainter.   these colors can only be explained with significant changes in the structure of the inner disk.   no relation between mid - ir variability and stellar effective temperature or x - ray spectrum is found.
we use two models of nuclear collective dynamics  the geometric collective model and the interacting boson model  to illustrate principles of classical and quantum chaos.   we propose these models as a suitable testing ground for further elaborations of the general theory of chaos in both classical and quantum domains.   address = institute of particle and nuclear physics, faculty of mathematics and physics, charles university, + v holeovikch 2, 18000 prague, czech republic     address = instituto de ciencias nucleares, universidad nacional autnoma de mxico, 04510, mxico, d.f.,
we present a cluster dynamical mean - field treatment of the hubbard model on a square lattice to study the evolution of magnetism and quasiparticle properties as the electron filling and interaction strength are varied.   our approach for solving the dynamical mean - field equations is an extension of potthoff s `` two - site '' method [ phys.   rev.   b. * 64 *, 165114 ( 2001 ) ] where the self - consistent bath is represented by a highly restricted set of states. as well as the expected antiferromagnetism close to half - filling, we observe distortions of the fermi surface. the proximity of a van hove point and the incipient antiferromagnetism lead to the evolution from an electron - like fermi surface away from the mott transition, to a hole - like one near half - filling.   our results also show a gap opening anisotropically around the fermi surface close to the mott transition ( reminiscent of the pseudogap phenomenon seen in the cuprate high-@xmath0 superconductors ).   this leaves fermi arcs which are closed into pockets by lines with very small quasiparticle residue.
we study the motion of magnetic skyrmions in a nanowire induced by a spin - wave current @xmath0 flowing out of a driving layer close to the edge of the wire. by applying micromagnetic simulation and an analysis of the effective thiele equation  , we find that the skyrmion trajectory is governed by an interplay of both forces due to the magnon current and the wire boundary.   the skyrmion is attracted to the driving layer and is accelerated by the repulsive force due to the wire boundary.   we consider both cases of a driving longitudinal and transverse to the nanowire, but a steady - state motion of the skyrmion is only obtained for a transverse magnon current. for the latter case, we find in the limit of low current densities @xmath0 the velocity - current relation @xmath1 where @xmath2 is the skyrmion velocity and @xmath3 is the gilbert damping. for large @xmath0 in case of strong driving, the skyrmion is pushed into the driving layer resulting in a drop of the skyrmion velocity and, eventually, the destruction of the skyrmion.
micro - blogging systems such as twitter expose digital traces of social discourse with an unprecedented degree of resolution of individual behaviors.   they offer an opportunity to investigate how a large - scale social system responds to exogenous or endogenous stimuli, and to disentangle the temporal, spatial and topical aspects of users activity. here   we focus on spikes of collective attention in twitter, and specifically on peaks in the popularity of hashtags.   users employ hashtags as a form of social annotation, to define a shared context for a specific event, topic, or meme.   we analyze a large - scale record of twitter activity and find that the evolution of hashtag popularity over time defines discrete classes of hashtags.   we link these dynamical classes to the events the hashtags represent and use text mining techniques to provide a semantic characterization of the hashtag classes.   moreover, we track the propagation of hashtags in the twitter social network and find that epidemic spreading plays a minor role in hashtag popularity, which is mostly driven by exogenous factors.   = 10000 = 10000     
the compressibility of molecular cloud ( mc ) turbulence plays a crucial role in star formation models, because it controls the amplitude and distribution of density fluctuations.   the relation between the compressive ratio ( the ratio of powers in compressive and solenoidal motions ) and the statistics of turbulence has been previously studied systematically only in idealized simulations with random external forces. in this work,   we analyze a simulation of large - scale turbulence ( 250 pc ) driven by supernova ( sn ) explosions that has been shown to yield realistic mc properties.   we demonstrate that sn driving results in mc turbulence with a broad lognormal distribution of the compressive ratio, with a mean value @xmath0, lower than the equilibrium value of @xmath1 found in the inertial range of isothermal simulations with random solenoidal driving.   we also find that the compressibility of the turbulence is not noticeably affected by gravity, nor are the mean cloud radial ( expansion or contraction ) and solid - body rotation velocities.   furthermore, the clouds follow a general relation between the rms density and the rms mach number similar to that of supersonic isothermal turbulence, though with a large scatter, and their average gas density pdf is described well by a lognormal distribution, with the addition of a high - density power - law tail when self - gravity is included.
* we introduce a `` hamiltonian''-like function, called the volume function, indispensable to describe the ensemble of jammed matter such as granular materials and emulsions from a geometrical point of view.   the volume function represents the available volume of each particle in the jammed systems. at the microscopic level, we show that the volume function is the voronoi volume associated to each particle and in turn we provide an analytical formula for the voronoi volume in terms of the contact network, valid for any dimension.   we then develop a statistical theory for the probability distribution of the volumes in 3d to calculate an average volume function coarse - grained at a mesoscopic level.   the salient result is the discovery of a mesoscopic volume function inversely proportional to the coordination number.   our analysis is the first step toward the calculation of macroscopic observables and equations of state using the statistical mechanics of jammed matter, when supplemented by the condition of mechanical equilibrium of jamming that properly defines jammed matter at the ensemble level. *
the transport properties of dense stellar electron - proton plasma is studied following an exact relativistic formalism in presence of strong quantizing magnetic field.   the variation of transport coefficients with magnetic fields are found to be insensitive for the field strengths @xmath0 g, beyond which all of them abruptly go to zero. as a consequence  , the electron - proton plasma behaves like a superfluid insulator in presence of ultra - strong magnetic field.   pacs:97.60.jd, 97.60.-s, 75.25.+z
in a companion paper we introduced a kinematical arena for the discussion of the constraints of canonical quantum gravity in the spin network representation based on vassiliev invariants. in this paper   we introduce the hamiltonian constraint, extend the space of states to non - diffeomorphism invariant `` habitats '' and check that the off - shell quantum constraint commutator algebra reproduces the classical poisson algebra of constraints of general relativity without anomalies.   one can therefore consider the resulting set of constraints and space of states as a consistent theory of canonical quantum gravity.   psfig # 1#1    psfig    cgpg-99/11 - 1 + gr - qc/9911010 +
contraction theory is a powerful tool for proving asymptotic properties of nonlinear dynamical systems including convergence to an attractor and entrainment to a periodic excitation.   these generalized contractive systems  ( gcss ) are useful for several reasons.   first, we show that there exist simple and checkable conditions guaranteeing that a system is a gcs, and demonstrate their usefulness using several models from systems biology.   second, allowing small transients does not destroy the important asymptotic properties of contractive systems.   third, in some cases as we change the parameters in a contractive system it becomes a  gcs just before it looses. in this respect,   generalized contractivity is the analogue of marginal stability in lyapunov stability theory.   differential analysis, contraction, stability, entrainment, phase locking, systems biology.
a method to construct exact general relativistic thick disks that is a simple generalization of the `` displace, cut and reflect '' method commonly used in newtonian, as well as, in einstein theory of gravitation is presented.   this generalization consists in the addition of a new step in the above mentioned method.   the new method can be pictured as a `` displace, cut, _ fill _ and reflect '' method. in the newtonian case,   the method is illustrated in some detail with the kuzmin - toomre disk.   we obtain a thick disk with acceptable physical properties. in the relativistic case   two solutions of the weyl equations, the weyl gamma metric ( also known as zipoy - voorhees metric ) and the chazy - curzon metric are used to construct thick disks.   also the schwarzschild metric in isotropic coordinates is employed to construct another family of thick disks. in all the considered cases we have non trivial ranges of the involved parameter that yield thick disks in which all the energy conditions are satisfied.
i discuss some observational properties of aspherical nebulae around massive stars, and conclusions inferred for how they may have formed.   whether or not these ideas are applicable to the shaping of planetary nebulae is uncertain, but the observed similarities between some pne and bipolar nebulae around massive stars is compelling. in the well - observed case of eta carinae, several lines of observational evidence point to a scenario where the shape of its bipolar nebula resulted from an intrinsically bipolar explosive ejection event rather than an interacting winds scenario occurring after ejection from teh star.   a similar conclusion has been inferred for some planetary nebulae.   i also briefly mention bipolar nebulae around some other massive stars, such as the progenitor of sn  1987a and related blue supergiants.
it is suggested that m31 was created by the early merger, and subsequent violent relaxation, of two or more massive metal - rich ancestral galaxies within the core of the andromeda subgroup of the local group. on the other hand the evolution of the main body of the galaxy appears to have been dominated by the collapse of a single ancestral object, that subsequently evolved by capturing a halo of small metal - poor companions.   it remains a mystery why the globular cluster systems surrounding galaxies like m33 and the lmc exhibit such striking differences in evolutionary history.   it is argued that the first generation of globular clusters might have been formed nearly simultaneously in all environments by the strong pressure increase that accompanied cosmic reionization. on the other hand subsequent generations of globulars   may have formed during starbursts that were triggered by collisions and mergers of gas rich galaxies.    _ the fact that the alactic system is a member of a group is a very fortunate accident. _ hubble ( 1936, p.125 )
using the dynamical triangulation approach we perform a numerical study of a supersymmetric random surface model that corresponds to the large @xmath0 limit of the four  dimensional version of the ikkt matrix model.   we show that the addition of fermionic degrees of freedom suppresses the spiky world - sheet configurations that are responsible for the pathological behaviour of the purely bosonic model.   we observe that the distribution of the gyration radius has a power  like tail @xmath1.   we check numerically that when the number of fermionic degrees of freedom is not susy  balanced, @xmath2 grows with @xmath3 and the model is not well  defined.   numerical sampling of the configurations in the tail of the distribution shows that the bosonic degrees of freedom collapse to a one  dimensional tube with small transverse fluctuations. assuming that the vertex positions can fluctuate independently within the tube  , we give a theoretical argument which essentially explains the behaviour of @xmath2 in the different cases, in particular predicting @xmath4 in the supersymmetric case. extending the argument to six and ten dimensions  , we predict @xmath5 and @xmath6, respectively.   bi - tp 00/18 +    p.   bialas@xmath7, z. burda@xmath8, b. petersson@xmath9, j.  tabaczek@xmath9    @xmath9fakultt fr physik, universitt bielefeld    p.o.box 100131, d-33501 bielefeld, germany    @xmath10inst. of comp.   science, jagellonian university    33 - 072 krakow, poland    @xmath11inst. of
every year the phenix collaboration deals with increasing volume of data ( now about 1/4 pb / year ).   apparently the more data the more questions how to process all the data in most efficient way. in recent past   many developments in hep computing were dedicated to the production environment.   now we need more tools to help to obtain physics results from the analysis of distributed simulated and experimental data.   developments in grid architectures gave many examples how distributed computing facilities can be organized to meet physics analysis needs.   we feel that our main task in this area is to try to use already developed systems or system components in phenix environment.   we are concentrating here on the followed problems : file / replica catalog which keep names of our files, data moving over wan, job submission in multicluster environment.   phenix is a running experiment and this fact narrowed our ability to test new software on the collaboration computer facilities.   we are experimenting with system prototypes at state university of new york at stony brook ( sunysb ) where we run midrange computing cluster for physics analysis @xcite.   the talk is dedicated to discuss some experience with grid software and achieved results.
electronic nematicity, proposed to exist in a number of transition metal materials, can have different microscopic origins.   in particular, the anisotropic resistivity and meta - magnetic jumps observed in sr@xmath0ru@xmath1o@xmath2 are consistent with an earlier proposal that the isotropic - nematic transition is generically first order and accompanied by meta - magnetism when tuned by a magnetic field.   however, additional striking experimental features such as a non - fermi liquid resistivity and critical thermodynamic behaviour imply the presence of an unidentified quantum critical point ( qcp ). here   we show that orbital degrees of freedom play an essential role in revealing a nematic qcp, even though it is overshadowed by a nearby meta - nematic transition at low temperature.   we further present a finite temperature phase diagram including the entropy landscape and discuss our findings in light of the phenomena observed in sr@xmath0ru@xmath1o@xmath2.
the potential capabilities of resonators based on two dimensional arrays of re - entrant posts is demonstrated.   such posts may be regarded as magnetically - coupled lumped element microwave harmonic oscillators, arranged in a 2d lattices structure, which is enclosed in a 3d cavity. by arranging these elements in certain 2d patterns,   we demonstrate how to achieve certain requirements with respect to field localisation and device spectra.   special attention is paid to symmetries of the lattices, mechanical tuning, design of areas of high localisation of magnetic energy, which in turn creates unique discrete mode spectra.   we demonstrate analogies between systems designed on the proposed platform and well known physical phenomena such as polarisation, frustration and whispering gallery modes.   the mechanical tunability of the cavity with multiple posts is analysed and its consequences to optomechanical applications is calculated.   one particular application to quantum memory is demonstrated with a cavity design consisting of separate resonators analogous to discrete fabry - prot resonators.   finally, we propose a generalised approach to a microwave system design based on the concept of programmable cavity arrays.
when sheets of layered material like c, ws@xmath0 or bn are restricted to finite sizes, they generally form single- and multi - walled hollow nanoparticles in order to avoid dangling bonds.   using continuum approaches to model elastic deformation and van der waals interactions of spherical nanoparticles, we predict the variation of mechanical stability, adhesive properties and phase behavior with radius @xmath1 and thickness @xmath2.   we find that mechanical stability is limited by forces in the nn range and pressures in the gpa range.   adhesion energies scale linearly with @xmath1, but depend only weakly on @xmath2.   deformation due to van der waals adhesion occurs for single - walled particles for radii of few nm, but is quickly suppressed for increasing thickness.   as @xmath1 is increased, the gas - liquid coexistence disappears from the phase diagram for particle radii in the range of 1 - 3 nm ( depending on wall thickness ) since the interaction range decreases like @xmath3.
the entropy of a polymer confined in a curved surface and the elastic free energy of a membrane consisting of polymers are obtained by scaling analysis.   it is found that the elastic free energy of the membrane has the form of the in - plane strain energy plus helfrich s curvature energy [ z. naturforsch.   c * 28 *, 693 ( 1973 ) ].   the elastic constants in the free energy are obtained by discussing two simplified models : one is the polymer membrane without in - plane strains and asymmetry between its two sides, which is the counterpart of quantum mechanics in curved surface [ jensen and koppe, ann.   phys.   * 63 *, 586 ( 1971 ) ] ; another is the planar rubber membrane with homogeneous in - plane strains.   the equations to describe equilibrium shape and in - plane strains of the polymer vesicles by osmotic pressure are derived by taking the first order variation of the total free energy containing the elastic free energy, the surface tension energy and the term induced by osmotic pressure.   the critical pressure, above which spherical polymer vesicle will lose its stability, is obtained by taking the second order variation of the total free energy.   it is found that the in - plane mode also plays important role in the critical pressure because it couples with the out - of - plane mode.   theoretical results reveal that polymer vesicles possess the mechanical properties intermediate between fluid membranes and solid shells.
we describe and present initial results of a weak lensing survey of nearby ( @xmath0 ) galaxy clusters in the sloan digital sky survey ( sdss ). in this first study,   galaxy clusters are selected from the sdss spectroscopic galaxy cluster catalogs of @xcite and @xcite.   we report a total of seven individual low redshift cluster weak lensing measurements which include : a2048, a1767, a2244, a1066, a2199, and two clusters specifically identified with the c4 algorithm.   our program of weak lensing of nearby galaxy clusters in the sdss will eventually reach @xmath1 clusters, making it the largest weak lensing survey of individual galaxy clusters to date.
we investigate the effective interaction between two randomly charged but otherwise net - neutral, planar dielectric slabs immersed in an asymmetric coulomb fluid containing a mixture of mobile monovalent and multivalent ions.   the presence of charge disorder on the apposed bounding surfaces of the slabs leads to substantial qualitative changes in the way they interact, as compared with the standard picture provided by the van der waals and image - induced, ion - depletion interactions. while, the latter predict purely attractive interactions between strictly neutral slabs, we show that the combined effects from surface charge disorder, image depletion, debye ( or salt ) screening and also, in particular, their coupling with multivalent ions, give rise to a more diverse behavior for the effective interaction between net - neutral slabs.   disorder effects show large variation depending on the properly quantified strength of disorder, leading either to non - monotonic effective interaction with both repulsive and attractive branches when the surface charges are weakly disordered ( small disorder variance ) or to a dominating attractive interaction that is larger both in its range and magnitude than what is predicted from the van der waals and image - induced, ion - depletion interactions, when the surfaces are strongly disordered ( large disorder variance ).
we study the modification of the far - field cross sections and the near - field enhancement for gold and silver nanospheres illuminated by a tightly focused beam. using a multipole - expansion approach   we obtain an analytical solution to the scattering problem and provide insight on the effects of focusing on the optical response.   large differences with respect to mie theory are found especially when the nanoparticle supports quadrupole or higher - order resonances.
we show the existence of gap - townes solitons for the multidimensional gross - pitaeviskii equation with attractive interactions and in two- and three - dimensional optical lattices. in absence of the periodic potential   the solution reduces to the known townes solitons of the multi - dimensional nonlinear schrdinger equation, sharing with these the propriety of being unstable against small norm ( number of atoms ) variations.   we show that in the presence of the optical lattice the solution separates stable localized solutions ( gap - solitons ) from decaying ones, characterizing the delocalizing transition occurring in the multidimensional case.   the link between these higher dimensional solutions and the ones of one dimensional nonlinear schrdinger equation with higher order nonlinearities is also discussed.
we consider the embedding method of the superconformal group in four dimensions in the case of extended supersymmetry, hence generalizing the recent work of goldberger, skiba and son which was restricted at @xmath0.   moreover, we work out explicitly the case of @xmath1 chiral superfields in four dimensions, putting the component fields in correspondence with pascal s pyramid at layer @xmath2.   this correspondence is a generic property of the @xmath2-extended chiral sector.   -10 cm
we conduct a systematic investigation of the nuclear collective dynamics that emerges in systems with random two - body interactions.   we explore the development of the mean field and study its geometry.   we investigate multipole collectivities in the many - body spectra and their dependence on the underlying two - body interaction hamiltonian.   the quadrupole - quadrupole interaction component appears to be dynamically dominating in two - body random ensembles.   this quadrupole coherence leads to rotational spectral features and thus suggests the formation of the deformed mean - field of a specific geometry.
three identical bosons or fermions are considered in the limit of zero - range interactions and finite effective range. by using a two channel model,   we show that these systems are not integrable and that the wave function verifies specific continuity conditions at the contact of three particles.   this last feature permits us to solve a contradiction brought by the contact model which can lead to an opposite result concerning the integrability issue. for fermions, the vicinity of integrability   is characterized by large deviations with respect to the predictions of the bethe ansatz.   1- sorbonne universits, upmc univ paris 06, umr 7600, laboratoire de physique thorique de la matire condense, f-75005, paris, france + 2- cnrs, umr 7600, laboratoire de physique thorique de la matire condense, f-75005, paris, france
it is well - known that it is possible to construct a partially hyperbolic diffeomorphism on the 3-torus in a similar way than in kan s example.   it has two hyperbolic physical measures with intermingled basins supported on two embedded tori with anosov dynamics.   a natural question is how robust is the intermingled basins phenomenon for diffeomorphisms defined on boundaryless manifolds? in this work we study partially hyperbolic diffeomorphisms on the 3-torus and show that the intermingled basins phenomenon is not robust.
we provide an analytical description of the dynamics of an atom in an optical lattice using the method of perturbative adiabatic expansion.   a precise understanding of the lattice - atom interaction is essential to taking full advantage of the promising applications that optical lattices offer in the field of atom interferometry.   one such application is the implementation of large momentum transfer ( lmt ) beam splitters that can potentially provide multiple order of magnitude increases in momentum space separations over current technology.   we also propose interferometer geometries where optical lattices are used as waveguides for the atoms throughout the duration of the interferometer sequence.   such a technique could simultaneously provide a multiple order of magnitude increase in sensitivity and a multiple order of magnitude decrease in interferometer size for many applications as compared to current state - of - the - art atom interferometers.
we present evidence that the non - anticommutativity parameter for the @xmath0 supersymmetric @xmath1 gauge theory is unrenormalised through two loops.   lth899 +    renormalisation of the non - anticommutativity parameterat two loops + * i.  jack and r.  purdy * + dept. of mathematical sciences,   university of liverpool, liverpool l69 3bx, uk +
the question  what is the observable electromagnetic ( em ) signature of a compact binary merger? " is an intriguing one with crucial consequences to the quest for gravitational waves ( gw ).   compact binary mergers are prime sources of gw, targeted by current and next generation detectors.   numerical simulations have demonstrated that these mergers eject energetic sub - relativistic ( or even relativistic ) outflows.   this is certainly the case if the mergers produce short grbs, but even if not, significant outflows are expected.   the interaction of such outflows with the surround matter inevitably leads to a long lasting radio signal.   we calculate the expected signal from these outflows ( our calculations are also applicable to short grb orphan afterglows ) and we discuss their detectability.   we show that the optimal search for such signal should, conveniently, take place around 1.4 ghz.   realistic estimates of the outflow parameters yield signals of a few hundred @xmath0jy, lasting a few weeks, from sources at the detection horizon of advanced gw detectors.   followup radio observations, triggered by gw detection, could reveal the radio remnant even under unfavorable conditions.   upcoming all sky surveys can detect a few dozen, and possibly even thousands, merger remnants at any give time, thereby providing robust merger rate estimates even before the advanced gw detectors become operational.   in fact, the radio transient rt 19870422 fits well the overall properties predicted by our model and we suggest that its most probable origin is a compact binary merger radio remnant.
sparse - to - dense interpolation for optical flow is a fundamental phase in the pipeline of most of the leading optical flow estimation algorithms.   the current state - of - the - art method for interpolation, epicflow, is a local average method based on an edge aware geodesic distance.   we propose a new data - driven sparse - to - dense interpolation algorithm based on a fully convolutional network.   we draw inspiration from the filling - in process in the visual cortex and introduce lateral dependencies between neurons and multi - layer supervision into our learning process.   we also show the importance of the image contour to the learning process.   our method is robust and outperforms epicflow on competitive optical flow benchmarks with several underlying matching algorithms.   this leads to state - of - the - art performance on the sintel and kitti 2012 benchmarks.
we present a new approach to calculate the attractive long range vortex - vortex interaction of the van der waals type present in anisotropic and layered superconductors.   the mapping of the statistical mechanics of vortex lines onto the imaginary time quantum mechanics of two dimensional charged bosons allows us to define a 2d casimir problem : two half - spaces of ( dilute ) vortex matter separated by a gap of width @xmath0 are mapped to two dielectric half - planes of charged bosons interacting via a massive gauge field.   we determine the attractive casimir force between the two half - planes and show, that it agrees with the pairwise summation of the van der waals force between vortices previously found by blatter and geshkenbein [ phys.   rev.   lett.   * 77 *, 4958 ( 1996 ) ].    2
l. kauffman conjectured that a particular solution of the chinese rings puzzle is the simplest possible.   we prove his conjecture by using low - dimensional topology and group theory.   we notice also a surprising connection between the chinese rings and habiro moves ( related to vassiliev invariants ).
we show that quadratic divergences in top - quark condensation are cancelled when the tadpoles cancel.   this latter cancellation is naturally implemented as the cancellation among the top - quark, goldstone and higgs contributions.   we also calculate the bosonic correction terms to gribov s mass formula for the higgs boson.   these reduce the prediction for @xmath0 from @xmath1  gev to @xmath2  gev.   the tadpole cancellation condition by itself is an independent condition on the mass of the higgs boson which, in gribov s u(1)@xmath3 scenario, yields @xmath4  gev with large theoretical uncertainty.   more generally, we are able to obtain all three masses, @xmath5, @xmath6 and @xmath0, in @xmath7  mev to @xmath8  tev energy range as a function of the cut - off scale and the gauge couplings only.
we investigate numerically the hydrodynamic instability of an ionization front ( if ) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes.   when the initial amplitude is small, the imposed perturbation is completely stabilized and does not grow.   when the initial perturbation amplitude is large enough, roughly the ratio of the initial amplitude to wavelength is greater than 0.02, portions of the if temporarily separate from the molecular cloud surface, locally decreasing the ablation pressure.   this causes the appearance of a large, warm hi region and triggers nonlinear dynamics of the if.   the local difference of the ablation pressure and acceleration enhances the appearance and growth of a multimode perturbation.   the stabilization usually seen at the if in the linear regimes does not work due to the mismatch of the modes of the perturbations at the cloud surface and in density in hii region above the cloud surface.   molecular pillars are observed in the late stages of the large amplitude perturbation case.   the velocity gradient in the pillars is in reasonably good agreement with that observed in the eagle nebula.   the initial perturbation is imposed in three different ways : in density, in incident photon number flux, and in the surface shape.   all cases show both stabilization for a small initial perturbation and large growth of the second harmonic by increasing amplitude of the initial perturbation above a critical value.
we study the connection between the cumulants of a time - integrated observable of a quantum system and the @xmath0-symmetry properties of the non - hermitian deformation of the hamiltonian from which the generating function of these cumulants is obtained.   this non - hermitian hamiltonian can display regimes of broken and of unbroken @xmath0-symmetry, depending on the parameters of the problem and on the counting field that sets the strength of the non - hermitian perturbation.   this in turn determines the analytic structure of the long - time cumulant generating function ( cgf ) for the time - integrated observable.   we consider in particular the case of the time - integrated ( longitudinal ) magnetisation in the one - dimensional ising model in a transverse field.   we show that its long - time cgf is singular on a curve in the magnetic field / counting field plane that delimits a regime where @xmath0-symmetry is spontaneously broken ( which includes the static ferromagnetic phase ), from one where it is preserved ( which includes the static paramagnetic phase ). in the paramagnetic phase, conservation of @xmath0-symmetry   implies that all cumulants are sub - linear in time, a behaviour usually associated to the absence of decorrelation.
we report the detection and observed characteristics of giant pulses from the crab nebula pulsar ( b0531 + 21 ) in four frequency bands covering 2084  mhz using the recently - completed long wavelength array station  1 ( lwa1 ) radio telescope. in 10  hours of observations distributed over a 72  day period in fall of 2012  , 33 giant pulses having peak flux densities between @xmath0  jy and @xmath1  jy were detected.   twenty - two of these pulses were detected simultaneously in channels of 16 mhz bandwidth centered at 44  mhz, 60  mhz, and 76  mhz, including one pulse which was also detected in a channel centered at 28  mhz.   we quantify statistics of pulse amplitude and pulse shape characteristics, including pulse broadening.   amplitude statistics are consistent with expectations based on extrapolations from previous work at higher and lower frequencies.   pulse broadening is found to be relatively high, but not significantly greater than expected.   we present procedures that have been found to be effective for observing giant pulses in this frequency range.
we study eigenmodes of acoustic oscillations of high multipolarity @xmath0  @xmath1 and high frequency ( @xmath2 khz ), localized in neutron star envelopes.   we show that the oscillation problem is self - similar.   once the oscillation spectrum is calculated for a given equation of state ( eos ) in the envelope and given stellar mass @xmath3 and radius @xmath4, it can be rescaled to a star with any @xmath3 and @xmath4 ( but the same eos in the envelope ).   for @xmath5 the modes can be subdivided into the outer and inner ones.   the outer modes are mainly localized in the outer envelope.   the inner modes are mostly localized near the neutron drip point, being associated with the softening of the eos after the neutron drip.   we calculate oscillation spectra for the eoss of cold - catalyzed and accreted matter and show that the spectra of the inner modes are essentially different.   a detection and identification of high - frequency pressure modes would allow one to infer @xmath3 and @xmath4 and determine also the eos in the envelope ( accreted or ground - state ) providing thus a new and simple method to explore the main parameters and internal structure of neutron stars.       stars : neutron  stars : oscillations.
magneto - convection can produce an active region without an initial coherent flux tube.   a simulation was performed where uniform, untwisted, horizontal magnetic field of 1 kg strenght was advected into the bottom of a computational domain 48 mm wide by 20 mm deep.   the up and down convective motions produce a hierarchy of magnetic loops with a wide range of scales, with smaller loops riding  piggy back " in a serpentine fashion on larger loops.   when a large loop approaches the surface it produces an small active region with a compact leading spot and more diffuse following spots.
we study the single productions of supersymmetric particles at tevatron run ii which occur in the @xmath0 processes involving r - parity violating couplings of type @xmath1.   we focus on the single gaugino productions which receive contributions from the resonant slepton productions.   we first calculate the amplitudes of the single gaugino productions.   then we perform analyses of the single gaugino productions based on the three charged leptons and like sign dilepton signatures.   these analyses allow to probe supersymmetric particles masses beyond the present experimental limits, and many of the @xmath2 coupling constants down to values smaller than the low - energy bounds.   finally, we show that the studies of the single gaugino productions offer the opportunity to reconstruct the @xmath3, @xmath4, @xmath5 and @xmath6 masses with a good accuracy in a model independent way.      -1 in -1 in @twoside 45
all swarm - intelligence - based optimization algorithms use some stochastic components to increase the diversity of solutions during the search process. such randomization is often represented in terms of random walks. however, it is not yet clear why some randomization techniques ( and thus why some algorithms ) may perform better than others for a given set of problems. in this work  , we analyze these randomization methods in the context of nature - inspired algorithms.   we also use eagle strategy to provide basic observations and relate step sizes and search efficiency using markov theory. then  , we apply our analysis and observations to solve four design benchmarks, including the designs of a pressure vessel, a speed reducer, a pid controller and a heat exchanger.   our results demonstrate that eagle strategy with lvy flights can perform extremely well in reducing the overall computational efforts.   * citation details : * x. s. yang, m. karamanoglu, t. o. ting and y. x. zhao, applications and analysis of bio - inspired eagle strategy for engineering optimization _ neural computing and applications _, vol. 25, no. 2, pp.   411 - 420 ( 2014 ).
we note that galaxy - galaxy lensing by non - spherical galaxy halos produces a net anti - correlation between the shear of background galaxies and the ellipticity of foreground galaxies.   this anti - correlation would contaminate the tomographic cosmological weak lensing two point function if the effect were not taken into account.   we compare the size of the galaxy - galaxy lensing contribution to the change in the cosmic shear two - point cross - correlation function due to a change in the dark energy equation of state @xmath0 of 1%.   we find them comparable on scales @xmath1 for nfw galaxy profiles, and out to much larger scales for sie profiles.   however the galaxy - galaxy lensing signal has a characteristic spatial and redshift pattern which should allow it to be removed.
adiabatic techniques are well known tools in multi - level electron systems to transfer population between different states with high fidelity  . recently it has been realised that these ideas can also be used in ultra - cold atom systems to achieve coherent manipulation of the atomic centre - of - mass states. here   we present an investigation into a realistic setup using three atomic waveguides created on top of an atom chip and show that such systems hold large potential for the observation of adiabatic phenomena in experiments.
we report results on an `` one - way light path '' laser diffraction experiment as a function of the laser beam alignment relative to the earth s velocity vector obtained by cobe measurements of the doppler shift in the cosmic microwave background radiation ( cmbr ).   an amplified doppler shift is observed in the diffraction images, and the effect is compatible with a `` dipole '' speed of light anisotropy due to earth s motion relative to the `` cmbr rest frame '', with an amplitude of @xmath0.   this amplitude coincides with the value of the dipole temperature anisotropy @xmath1 of the cmbr obtained by cobe.   our results point out that it is not possible to neglect the preferred frame imposed by the cosmology and they are well described by the ether gauge theory ( an extension of the lorentz s ether theory ) and it satisfies the cosmological time boundary condition.
we report the detection of molecular clouds around the x - ray bright interior feature in the galactic supernova remnant ( snr ) ctb  109  ( g109.11.0 ).   this feature, called the lobe, has been previously suggested to be the result of an interaction of the snr shock wave with a molecular cloud complex.   we present new high resolution x - ray data from the _ chandra _  x - ray observatory and new high resolution co data from the five college radio observatory which show the interaction region with the cloud complex in greater detail.   the co data reveal three clouds around the lobe in the velocity interval @xmath0.   the velocity profiles of @xmath1co at various parts of the east cloud are well fit with a gaussian ; however, at the position where the co cloud and the lobe overlap, the velocity profile has an additional component towards higher negative velocities.   the molecular hydrogen density in this part of the cloud is relatively high (  @xmath2  @xmath3 ), whereas the foreground absorption in x - rays (  @xmath4  @xmath3 ), obtained from _ chandra _   data, is lower than in other parts of the cloud and in the north and south cloud.   these results indicate that this cloud has been hit by the snr blast wave on the western side, forming the bright x - ray lobe.
we have constructed the @xmath0 potential for the collision between two ground state mg atoms and analyzed the effect of uncertainties in the shape of the potential on scattering properties at ultra - cold temperatures.   this potential reproduces the experimental term values to 0.2 @xmath1 and has a scattering length of + 1.4(5 ) nm where the error is prodominantly due to the uncertainty in the dissociation energy and the @xmath2 dispersion coefficient.   a positive sign of the scattering length suggests that a bose - einstein condensate of ground state mg atoms is stable.
bars in gas - rich spiral galaxies are short - lived.   they drive gas inflows through their gravity torques, and at the same time self - regulate their strength.   their robustness has been subject of debate, since it was thought that only the resulting central mass concentrations ( cmcs ) were weakening bars, and only relatively rare massive cmcs were able to completely destroy them. through numerical simulations including gas dynamics  , we find that with the gas parameters of normal spiral galaxies, the cmc is not sufficient to fully dissolve the bar. but   another overlooked mechanism, the transfer of angular momentum from the infalling gas to the stellar bar, can also strongly weaken the bar. in addition, we show that gravity torques are correctly reproduced in simulations, and conclude that bars are transient features, with life - time of 1 - 2 gyr in typical sb - sc galaxies, because of the combined effects of cmcs and gravity torques, while most existing works had focussed on the cmc effects alone.       galaxies : evolution  galaxies : spiral  galaxies : structure  galaxies : kinematics and dynamics.
binary quantum information can be fault tolerantly encoded in states defined in infinite dimensional hilbert spaces.   such states define a computational basis, and permit a perfect equivalence between continuous and discrete universal operations.   the drawback of this encoding is that the corresponding logical states are unphysical, meaning infinitely localized in phase space.   we use the modular variables formalism to show that, in a number of protocols relevant for quantum information and for the realization of fundamental tests of quantum mechanics, it is possible to loosen the requirements on the logical subspace without jeopardizing their usefulness or their successful implementation.   such protocols involve measurements of appropriately chosen modular variables that permit the readout of the encoded discrete quantum information from the corresponding logical states.   finally, we demonstrate the experimental feasibility of our approach by applying it to the transverse degrees of freedom of single photons.
velocity errors in particle tracking velocimetry ( ptv ) are studied.   when using high - speed video cameras, the velocity error may increase at a high camera frame rate.   this increase in velocity error is due to particle - position uncertainty, which is one of two sources of velocity errors studied here.   the other source of error is particle acceleration, which has the opposite trend of diminishing at higher frame rates. both kinds of errors can propagate into quantities calculated from velocity, such as the kinetic temperature of particles or correlation functions. as demonstrated in a dusty plasma experiment  , the kinetic temperature of particles has no unique value when measured using ptv, but depends on the sampling time interval or frame rate.   it is also shown that an artifact appears in an autocorrelation function computed from particle positions and velocities, and it becomes more severe when a small sampling - time interval is used.   schemes to reduce these errors are demonstrated.
we present an algorithm to approximate the solutions to variational problems where set of admissible functions consists of convex functions.   the main motivator behind this numerical method is estimating solutions to adverse selection problems within a principal - agent framework.   problems such as product lines design, optimal taxation, structured derivatives design, etc. can be studied through the scope of these models.   we develop a method to estimate their optimal pricing schedules.   preliminary - comments welcome    * ams classification * : 49 - 04, 49m25, 49m37, 65k10, 91b30, 91b32.   * keywords * : variational problems, convexity constraints, adverse selection, non - linear pricing, risk transfer, market screening.
we present a construction of invariants for links using an isomorphism theorem for affine yokonuma   hecke algebras.   the isomorphism relates affine yokonuma   hecke algebras with usual affine hecke algebras.   we use it to construct a large class of markov traces on affine yokonuma  hecke algebras, and in turn, to produce invariants for links in the solid torus. by restriction  , this construction contains the construction of invariants for classical links from classical yokonuma  hecke algebras. in general, the obtained invariants form an infinite family of 3-variables polynomials. as a consequence of the construction via the isomorphism, we reduce the number of invariants to study, given the number of connected components of a link.   in particular, if the link is a classical link with @xmath0 components, we show that @xmath0 invariants generate the whole family.
there is increasing circumstantial evidence that the cuprate superconductors, and correlated - electron materials generally, defy simple materials categorization because of their proximity to one or more continuous zero - temperature phase transitions.   this implies that the fifteen - year confusion about the cuprates is not fundamental at all but simply overinterpreted quantum criticality  an effect that seems mysterious by virtue of its hypersensitivity to perturbations, _   i.e. _ to sample imperfections in experiment and small modifications of approximation schemes in theoretical modeling, but is really just an unremarkable phase transition of some kind masquerading as something important, a sheep in wolf s clothing.   this conclusion is extremely difficult for most physicists even to think about because it requires admitting that an identifiable physical phenomenon might cause the scientific method to fail in some cases.   for this reason i have decided to explain the problem in a way that is nonthreatening, easy to read, and fun  as a satire modeled after a similar piece of lewis carroll s i once read.   my story is humorous fiction.   any similarity of the characters to living persons is accidental.   my apologies to henry w. longfellow.   
we report on the detection in the combined _ gaia_-dr1/rave data of a lack of disk stars in the solar neighbourhood with velocities close to zero angular momentum.   we propose that this may be caused by the scattering of stars with very low angular momentum onto chaotic, halo - type orbits when they pass through the galactic nucleus.   we model the effect in a milky - way like potential and fit the resulting model directly to the data, finding a likelihood ( @xmath0 ) of a dip in the distribution. using this effect  , we can make a dynamical measurement of the solar rotation velocity around the galactic center : @xmath1.   combined with the measured proper motion of sgr a@xmath2, this measurement gives a measurement of the distance to the galactic centre : @xmath3.
high - field magnetic white dwarfs have been long suspected to be the result of stellar mergers. however, the nature of the coalescing stars and the precise mechanism that produces the magnetic field are still unknown. here   we show that the hot, convective, differentially rotating corona present in the outer layers of the remnant of the merger of two degenerate cores is able to produce magnetic fields of the required strength that do not decay for long timescales.   we also show, using an state - of - the - art monte carlo simulator, that the expected number of high - field magnetic white dwarfs produced in this way is consistent with that found in the solar neighborhood.
in this work we consider optimal stopping problems with conditional convex risk measures of the form @xmath0- { \mathbb{e}}\left\right ), \ ] ] where @xmath1 $ ] is a lower semicontinuous convex mapping and @xmath2 stands for the set of all probability measures @xmath3 which are absolutely continuous w.r.t. a given measure @xmath4 and @xmath5 on @xmath6 here the _ model uncertainty risk _ depends on a ( random ) divergence @xmath7 $ ] measuring the distance between a hypothetical probability measure we are uncertain about and a reference one at time @xmath8 let @xmath9}$ ] be an adapted nonnegative, right - continuous stochastic process fulfilling some proper integrability condition and let @xmath10 be the set of stopping times on @xmath11 $ ], then without assuming any kind of time - consistency for the family @xmath12 we derive a novel representation @xmath13\right\},\end{aligned}\ ] ] which makes the application of the standard dynamic programming based approaches possible.   in particular, we generalize the additive dual representation of rogers, @xcite to the case of optimal stopping under uncertainty.   finally, we develop several monte carlo algorithms and illustrate their power for optimal stopping under average value at risk.
we report on an on - going analysis of high - resolution uv spectra of hot hydrogen - rich central stars of planetary nebulae ( cspn ), obtained with the hubble space telescope and fuse.   since uv spectra of many cspn are dominated by fe and ni lines, we intend to use them as temperature indicators to check the cspn temperature scale we have derived earlier from cno ionization balances.   furthermore, the observed line strengths of heavy metals show large variations between different objects suggesting a possible spread in abundances  . we will determine abundances of iron group elements by quantitative spectral analyses with non - lte model atmospheres.
x - ray emitting clusters of galaxies are considered in the context of modified newtonian dynamics ( mond ).   i show that self - gravitating isothermal gas spheres are not good representations of rich clusters with respect to the radial gas density distribution as indicated by the x - ray surface brightness.   pure gas spheres with a density distribution described by a @xmath0 model, as observed, also fail because, with mond, these objects are far from isothermal and have a gas mass and luminosity much larger than observed for clusters of the same mean temperature.   these problems may be resolved by adding an additional dark mass component in the central regions ; a constant density sphere contained within two core radii and having a total mass of one to two times that in the gas. with this additional component,   the observed luminosity - temperature relation for clusters of galaxies is reproduced.   when the observed x - ray surface brightness distribution in actual clusters is modeled by such a two - component structure, the typical mass discrepancy is three to four times smaller than with newtonian dynamics.   thus while mond significantly reduces the mass of the dark component in clusters it does not remove it completely.   i speculate on the nature of the dark component and argue that this is not a fundamental problem for mond.   galaxy clusters : x - ray emission : kinematics and dynamics dark matter, gravitation
there have been attempts to fit the abundance patterns of extremely metal - poor stars with supernova nucleosynthesis models for the lighter elements than zn. on the other hand  , observations have revealed that the presence of emp stars with peculiarly high ratio of `` weak r - process elements '' sr, y and zr.   although several possible processes were suggested for the origin of these elements, the complete solution for reproducing those ratios is not found yet. in order to reproduce the abundance patterns of such stars, we investigate a model with neutron rich matter ejection from the inner region of the conventional mass - cut.   we find that explosive nucleosynthesis in a high energy supernova ( or `` hypernova '' ) can reproduce the high abundances of sr, y and zr but that the enhancements of sr, y and zr are not achieved by nucleosynthesis in a normal supernova.   our results imply that, if these elements are ejected from a normal supernova, nucleosynthesis in higher entropy flow than that of the supernova shock is required.
extending the theory we derived recently for @xmath0 to different cases of strongly irradiated gaseous exoplanets, we have calculated the consistent evolution of the new transiting planet, @xmath1, for its recently revised mass determination.   the theory is shown to successfully reproduce the observed radius, for the proper age of the system.   we also examine the dissipation of kinetic energy at the planet s internal adiabat due to atmospheric winds, and place constraints on the efficiency of this process.   we show that a fraction @xmath2   @xmath3 of the incident flux transformed into thermal energy deposited at the adiabatic level can accommodate the observed radii of both @xmath1 and @xmath0.   the present theory yields quantitative predictions on the evolution of the emergent spectrum and fundamental properties of hot - jupiters.   the predictions for radius, luminosity, temperature as a function of the planet s mass and orbital distance can be used as benchmarks for future detections of transit planets.
accurate molecular crystal structure prediction is a fundamental goal in academic and industrial condensed matter research and polymorphism is arguably the biggest obstacle on the way.   we tackle this challenge in the difficult case of the repeatedly studied, abundantly used aminoacid glycine that hosts still little - known phase transitions and we illustrate the current state of the field through this example.   we demonstrate that the combination of recent progress in structure search algorithms with the latest advances in the description of van der waals interactions in density functional theory, supported by data - mining analysis, enables a leap in predictive power : we resolve, without prior empirical input, all known phases of glycine, as well as the structure of the previously unresolved @xmath0 phase after a decade of its experimental observation [ boldyreva et al.   _ z. kristallogr. _ * 2005, * _ 220,   _ 50 - 57 ].   the search for the well - established @xmath1 phase instead reveals the remaining challenges in exploring a polymorphic landscape.
using the _ herschel space observatory _   s heterodyne instrument for the far - infrared ( hifi ), we have performed mapping observations of the 620.701  ghz @xmath0 transition of ortho - h@xmath1o within a @xmath2 region encompassing the kleinmann - low nebula in orion, and pointed observations of that transition toward the orion south condensation and the w49n region of high - mass star formation. using the effelsberg 100 m radio telescope, we obtained ancillary observations of the 22.23508  ghz @xmath3 water maser transition ; in the case of orion - kl, the 621  ghz and 22  ghz observations were carried out within 10 days of each other.   the 621  ghz water line emission shows clear evidence for strong maser amplication in all three sources, exhibiting narrow ( @xmath4 km / s fwhm ) emission features that are coincident ( kinematically and/or spatially ) with observed 22  ghz features.   moreover, in the case of w49n  for which observations were available at three epochs spanning a two year period  the spectra exhibited variability.   the observed 621  ghz/22  ghz line ratios are consistent with a maser pumping model in which the population inversions arise from the combined effects of collisional excitation and spontaneous radiative decay, and the inferred physical conditions can plausibly arise in gas heated by either dissociative or non - dissociative shocks.   the collisional excitation model also predicts that the 22  ghz population inversion will be quenched at higher densities than that of the 621  ghz transition, providing a natural explanation for the observational fact that 22  ghz maser emission appears to be a necessary but insufficient condition
motivated by an axiomatic approach to characterize space - time it is investigated a reformulation of einstein s gravity where the pseudo - riemannian geometry is substituted by a weyl one. it is presented the main properties of the weyl geometry and it is shown that it gives extra contributions to the trajectories of test particles, serving as one more motivation to study general relativity in weyl geometry.   it is introduced its variational formalism and it is established the coupling with other physical fields in such a way that the theory acquires a gauge symmetry for the geometrical fields. it is shown that this symmetry is still present for the red - shift and, considering cosmological models, it opens the possibility that observations can be fully described by the new geometrical scalar field.   it is concluded then that this reformulation, although representing a theoretical advance, still needs a complete description of their objects.
alternative splicing is the post - transcriptional process by which a single gene can produce multiple transcripts and thereby protein isoforms.   the presence of different transcripts of a gene across samples can be analysed by whole - transcriptome microarrays. reproducing results from published microarray data   represents a challenge due to the vast amounts of data and the large variety of pre - processing and filtering steps employed before the actual analysis is carried out. to ensure a firm basis for methodological development where results with new methods are compared with previous results   it is crucial to ensure that all analyses are completely reproducible for other researchers.   we here give a detailed workflow on how to perform reproducible analysis of the genechip  human exon 1.0 st array at probe and probeset level solely in ` r`/bioconductor, choosing packages based on their simplicity of use. to exemplify the use of the proposed workflow we analyse differential splicing and differential gene expression in a publicly available dataset using various statistical methods.   we believe this study will provide other researchers with an easy way of accessing gene expression data at different annotation levels and with the sufficient details needed for developing their own tools for reproducible analysis of the genechip  human exon 1.0 st array. + * contact : * maria@math.aau.dk
in a recent contribution, @xcite investigated the incidence of planar alignments of satellite galaxies in the millennium - ii simulation, and concluded that vast thin planes of dwarf galaxies, similar to that observed in the andromeda galaxy ( m31 ), occur frequently by chance in @xmath0-cold dark matter cosmology  . however, their analysis did not capture the essential fact that the observed alignment is simultaneously radially extended, yet thin, and kinematically unusual. with the caveat that the millennium - ii simulation may not have sufficient mass resolution to identify confidently simulacra of low - luminosity dwarf galaxies, we re - examine that simulation for planar structures, using the same method as employed by ibata et al.   ( 2013 ) on the real m31 satellites.   we find that 0.04% of host galaxies display satellite alignments that are at least as extreme as the observations, when we consider their extent, thickness and number of members rotating in the same sense.   we further investigate the angular momentum properties of the co - planar satellites, and find that the median of the specific angular momentum derived from the line of sight velocities in the real m31 structure ( @xmath1 ) is very high compared to systems drawn from the simulations.   this analysis confirms that it is highly unlikely that the observed structure around the andromeda galaxy is due to a chance occurrence.   interestingly, the few extreme systems that are similar to m31 arise from the accretion of a massive sub - halo with its own spatially - concentrated entourage of orphan satellites.
a multiple access relay channel ( marc ) is considered in which an analogue - like network coding is implemented in the relay node.   this analogue coding is a simple addition of the received signals at the relay node. using `` nulling detection '' structure employed in v - blast receiver, we propose a detection scheme in the destination which is able to provide a diversity order of two for all users.   we analytically evaluate the performance of our proposed scheme for the marc with two users where tight upper bounds for both uncoded and convolutionally coded transmission blocks are provided.   we verify our analytical evaluations by simulations and compare the results with those of non - cooperative transmission and alamouti s scheme for the same power and rate transmission.   our results indicate that while our proposed scheme shows a comparable performance compared to the alamouti s scheme, it substantially outperforms the non - cooperate transmission.   cooperative communication, marc, analogue network coding, v - blast detection, alamouti space - time coding
in this article we develop quantum algorithms for learning and testing _ juntas _, i.e. boolean functions which depend only on an unknown set of @xmath0 out of @xmath1 input variables.   our aim is to develop efficient algorithms :    whose sample complexity has no dependence on @xmath1, the dimension of the domain the boolean functions are defined over ;    with no access to any classical or quantum membership ( `` black - box '' ) queries. instead,   our algorithms use only classical examples generated uniformly at random and fixed quantum superpositions of such classical examples ;    which require only a few quantum examples but possibly many classical random examples ( which are considered quite `` cheap '' relative to quantum examples ).   our quantum algorithms are based on a subroutine @xmath2 which enables sampling according to the fourier spectrum of @xmath3 ; the @xmath2 subroutine was used in earlier work of bshouty and jackson on quantum learning.   our results are as follows :    we give an algorithm for testing @xmath0-juntas to accuracy @xmath4 that uses @xmath5 quantum examples.   this improves on the number of examples used by the best known classical algorithm.   we establish the following lower bound : any @xmath2-based @xmath0-junta testing algorithm requires @xmath6 queries.   we give an algorithm for learning @xmath0-juntas to accuracy @xmath4 that uses @xmath7 quantum examples and @xmath8 random examples.   we show that this learning algorithms is close to optimal by giving a related lower bound.
smc 3 is one of the most interesting symbiotic stars.   this binary contains a bright k - type giant transferring mass to a massive white dwarf comanion, which makes it is a very promising sn ia candidate.   we discuss the evolutionary status of the system using results of population synthesis code.
an important problem in econometrics and marketing is to infer the causal impact that a designed market intervention has exerted on an outcome metric over time.   this paper proposes to infer causal impact on the basis of a diffusion - regression state - space model that predicts the counterfactual market response in a synthetic control that would have occurred had no intervention taken place.   in contrast to classical difference - in - differences schemes, state - space models make it possible to ( i ) infer the temporal evolution of attributable impact, ( ii ) incorporate empirical priors on the parameters in a fully bayesian treatment, and ( iii ) flexibly accommodate multiple sources of variation, including local trends, seasonality and the time - varying influence of contemporaneous covariates. using a markov chain monte carlo algorithm for posterior inference, we illustrate the statistical properties of our approach on simulated data.   we then demonstrate its practical utility by estimating the causal effect of an online advertising campaign on search - related site visits.   we discuss the strengths and limitations of state - space models in enabling causal attribution in those settings where a randomised experiment is unavailable.   the causalimpact r package provides an implementation of our approach.   ,   ,   ,
we study the sudden expansion of strongly correlated fermions in a one - dimensional lattice, utilizing the time - dependent density - matrix renormalization group method.   our focus is on the behavior of experimental observables such as the density, the momentum distribution function, and the density and spin structure factors. as our main result  , we show that correlations in the transient regime can be accurately described by _ equilibrium _ reference systems.   in addition, we find that the expansion from a mott insulator produces distinctive peaks in the momentum distribution function at @xmath0, accompanied by the onset of power - law correlations.
we consider a preferential growth model where particles are added one by one to the system consisting of clusters of particles.   a new particle can either form a new cluster ( with probability @xmath0 ) or join an already existing cluster with a probability proportional to the size thereof.   we calculate exactly the probability @xmath1 that the size of the @xmath2-th cluster at time @xmath3 is @xmath4.   we analyze the asymptotics, the scaling properties of the size distribution and of the mean size as well as the relation of our system to recent network models.   pacs numbers : 05.10.-a, 05.40.-a, 02.50.cw    = 0truecm
similarity solutions are found for the adiabatic collapse of density perturbations @xmath0 @xmath1 in a flat universe containing collisional gas only.   the solutions are obtained for planar, cylindrical, and spherical perturbations with zero initial pressure. for adiabatic index @xmath2,   a shock develops at a fixed fraction of the current turnaround distance. near the center of a spherical perturbations with @xmath3 and @xmath4,   the gas is in quasi - hydrostatic equilibrium ( pressure supported ) and has an asymptotic power law density profile, @xmath5, independent of @xmath6. for @xmath7,   the profile depends on @xmath6, the pressure is finite, the temperature decreases inward, and gravity dominates pressure causing a continuous inward flow. although for @xmath8 the temperature decreases at the center, the gas is pressure supported.   the pressure is finite in cylindrical perturbations for @xmath9, and in planar perturbations for any @xmath10.   we also derive the asymptotic behaviour of the gas variables near the center in a universe dominated by collisionless matter.   in such a universe, the gas in a spherical perturbation with @xmath11 can not be pressure supported and the temperature approaches a constant near the center.   the solutions and the asymptotic behaviour are relevant for modelling the gas distribution in galaxy clusters and pancake - like superclusters, and determining the structure of haloes of self - interacting dark matter with large interaction cross section.   # 10=-.025em0 - 0.05em0   - 0 -.025em.0433em0    cosmology : theory  gravitation  dark matter baryons intergalactic medium
we develop a theory of spin - dependent phenomena in the streaming regime characterized by ballistic acceleration of electrons in the moderate electric field until they achieve the optical phonon energy and abruptly emit the phonons.   it is shown that the dyakonov - perel spin relaxation is drastically modified in this regime, the current - induced spin orientation remarkably increases, reaches a high value @xmath0  % in the electric field @xmath1  kv / cm and falls with the further increase in the field.   the spin polarization enhancement is caused by squeezing of the electron momentum distribution in the direction of drift.   we also predict field - induced oscillatory dynamics of spin polarization of the photocarriers excited into the conduction band by a short circularly - polarized optical pulse.
the main goal of the alice experiment is to study the properties of the hot and dense medium created in ultra - relativistic heavy - ion collisions.   the measurement of the particles is an important tool to understand particle production mechanisms and the dynamics of the quark - gluon plasma ( qgp ).   we report on the production of k@xmath0,, and in proton - lead ( ) collisions at @xmath1 = 5.02 tev and lead - lead ( ) collisions at @xmath1 = 2.76 tev measured by alice at the lhc  . the comparison of the hyperon - to - pion ratios in the two colliding systems may provide insight into strangeness production mechanisms, while the comparison of the nuclear modification factors helps to determine the contribution of initial state effects and the suppression from strange quark energy loss in nuclear matter.
we argue that poisson statistics in logarithmic time provides an idealized description of non - equilibrium configurational rearrangements in aging glassy systems.   the description puts stringent requirements on the geometry of the metastable attractors visited at age @xmath0.   analytical implications for the residence time distributions as function of @xmath0 and the correlation functions are derived.   these are verified by extensive numerical studies of short range ising spin glasses.
we find a very strong correlation between the intrinsic spectral slope in x - rays and the amount of compton reflection from a cold medium in seyfert agns and in hard state of x - ray binaries with either black holes or weakly - magnetized neutron stars.   objects with soft intrinsic spectra show much stronger reflection than ones with hard spectra.   we find that at a given spectral slope, black - hole binaries have similar or more reflection than seyferts whereas neutron - star binaries in our sample have reflection consistent with that in seyferts.   the existence of the correlation implies a dominant role of the reflecting medium as a source of seed soft photons for thermal comptonization in the primary x - ray source.    -0.2   cm    = = = = = = = =    # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn @mathgroup@bold@groupeurbn @mathgroup@group @mathgroup@normal@groupmsamn @mathgroup@bold@groupmsamn = `` 019 ='' 016 = `` 040 ='' 336 = " 33e = = = = = = = =    # 1 # 1 # 1 # 1 = = = = = = = =        accretion, accretion discs  binaries : general  galaxies : seyfert  radiation mechanisms : thermal  x - rays : galaxies  x - rays : stars.
we report on the study of the intensities of several gamma lines emitted after the inelastic scattering of neutrons in @xmath0fe.   neutrons were produced by cosmic muons passing the 20 t massive iron cube placed at the earth s surface and used as a passive shield for the hpge detector.   relative intensities of detected gamma lines are compared with the results collected in the same iron shield by the use of @xmath1cf neutrons.   assessment against the published data from neutron scattering experiments at energies up to 14  mev is also provided.
it has been pointed out that the null energy condition can be violated stably in some non - canonical scalar - field theories.   this allows us to consider the galilean genesis scenario in which the universe starts expanding from minkowski spacetime and hence is free from the initial singularity.   we use this scenario to study the early - time completion of inflation, pushing forward the recent idea of pirtskhalava _   et al_. we present a generic form of the lagrangian governing the background and perturbation dynamics in the genesis phase, the subsequent inflationary phase, and the graceful exit from inflation, as opposed to employing the effective field theory approach.   our lagrangian belongs to a more general class of scalar - tensor theories than the horndeski theory and gleyzes - langlois - piazza - vernizzi generalization, but still has the same number of the propagating degrees of freedom, and thus can avoid ostrogradski instabilities.   we investigate the generation and evolution of primordial perturbations in this scenario and show that one can indeed construct a stable model of inflation preceded by ( generalized ) galilean genesis.
in this paper, a plasmonic absorber consisting of a metal - dielectric - metal stack with a top layer of sierpinski nanocarpet is theoretically investigated.   such compact absorber depicts broadband angle - independent behavior over a wide optical wavelength range ( @xmath0 nm ) and a broad range of angles of light incidence ( @xmath1 ). including several feature sizes, such fractal - like structure shows widely strong extinction ( @xmath2% ) response for either transverse electric or magnetic polarization states under normal incidence.   underlying mechanisms of absorbance due to excited surface plasmon modes as well as electric / magnetic dipole resonances are well revealed by investigating electric field, magnetic field and current distributions.   the proposed absorber opens a path to realize high - performance ultrathin light trapping devices.
to describe neutrino oscillations in the sense of quantum mechanics and quantum field theory, we propose to use an off - diagonal neutrino - higgs ( mass ) interaction, as discussed originally in a family gauge theory and in the extended standard model. for neutrino oscillations which take place presumably between point - like dirac particles,   the proposed description would be unique in the quantum mechanics sense. this may help us to resolve a few outstanding puzzles - the question of why there are only three generations, the question of why the masses of neutrinos are so tiny, the question of why neutrinos oscillate, and the question of why the dark - matter world is so huge ( 25% ) as compared to the visible ordinary - matter world ( 5% ).   pacs indices : 12.60.-i ( models beyond the standard model ) ; 98.80.bp ( origin and formation of the universe ) ; 12.10.-g ( unified field theories and models ).    * neutrino oscillations as a lepton - flavor - violating interaction *   .5 cm    w - y.   pauchy hwang 27 jul 2012. ]   + _ asia pacific organization for cosmology and particle astrophysics, + institute of astrophysics, center for theoretical sciences, + and department of physics, national taiwan university, taipei 106, taiwan _.2 cm    ( 24 july 2012 ; revised : august 15, 2013 )
we summarise the properties of the sloan digital sky survey ( sdss ) project, discuss our software infrastructure, and outline the architecture of the sdss image processing pipelines.   we then discuss two of the algorithms used in the sdss image processing ; the karhunen - love transform based modelling of the spatial variation of the psf, and the use of galaxy models in star / galaxy separation.   we conclude with the first author s personal opinions on the challenges that the astronomical community faces with major software projects.
an overview of some methods of statistical physics applied to the analysis of algorithms for optimization problems ( satisfiability of boolean constraints, vertex cover of graphs, decoding,... ) with distributions of random inputs is proposed.   two types of algorithms are analyzed : complete procedures with backtracking ( davis - putnam - loveland - logeman algorithm ) and incomplete, local search procedures ( gradient descent, random walksat,... ).   the study of complete algorithms makes use of physical concepts such as phase transitions, dynamical renormalization flow, growth processes,... as for local search procedures, the connection between computational complexity and the structure of the cost function landscape is questioned, with emphasis on the notion of metastability.
we study the collective excitation of a gas of highly excited atoms confined to a large spacing ring lattice, where the ground and the excited states are coupled resonantly via a laser field.   our attention is focused on the regime where the interaction between the highly excited atoms is very weak in comparison to the rabi frequency of the laser.   we demonstrate that in this case the many - body excitations of the system can be expressed in terms of free spinless fermions.   the complex many - particle states arising in this regime are characterized and their properties, e.g. their correlation functions, are studied.   in addition we investigate how one can actually experimentally access some of these many - particle states by a temporal variation of the laser parameters.
we consider the @xmath0=1 friedman - robertson - walker ( frw ) model within loop quantum cosmology, paying special attention to the existence of an ambiguity in the quantization process. in   spatially non - flat anisotropic models such as bianchi ii and ix, the standard method of defining the curvature through closed holonomies is not admissible.   instead, one has to implement the quantum constraints by approximating the connection via open holonomies. in the case of flat @xmath0=0 frw and bianchi i models,   these two quantization methods coincide, but in the case of the closed @xmath0=1 frw model they might yield different quantum theories. in this manuscript   we explore these two quantizations and the different effective descriptions they provide of the bouncing cyclic universe.   in particular, as we show in detail, the most dramatic difference is that in the theory defined by the new quantization method, there is not one, but _ two _ different bounces through which the cyclic universe alternates.   we show that for a ` large'universe, these two bounces are very similar and, therefore, practically indistinguishable, approaching the dynamics of the holonomy based quantum theory.
we propose the use of modulated spectra of astronomical sources due to gravitational lensing to probe ellis wormholes.   the modulation factor due to gravitational lensing by the ellis wormhole is calculated. within the geometrical optics approximation,   the normal point mass lens and the ellis wormhole are indistinguishable unless we know the source s unlensed luminosity.   this degeneracy is resolved with the significant wave effect in the low frequency domain if we take the deviation from the geometrical optics into account.   we can roughly estimate the upper bound for the number density of ellis wormholes as @xmath0 with throat radius @xmath1 from the existing femto - lensing analysis for compact objects.   5.5 mm
we present new results on the frequency distribution of projected column densities @xmath0, total comoving covering fraction, and integrated mass densities  of high redshift, ` disks'from a survey of damped ly@xmath1  systems ( dlas ) in the sloan digital sky survey, data release 5. for the full sample spanning @xmath2 to 5 ( 738 dlas ), @xmath0is well fitted by a double power - law with a break column density @xmath3 and low / high - end exponents @xmath4.   the shape of @xmath0  is invariant during this redshift interval and also follows the projected surface density distribution of present - day disks as inferred from 21 cm observations.   we conclude that gas has been distributed in a self - similar fashion for the past 12gyr.   the normalization of @xmath0, in contrast, decreases by a factor of two during the @xmath5gyr interval from @xmath6 to 2.2 giving corresponding decreases in both the total covering fraction and. at @xmath7,   these quantities match the present - day values suggesting no evolution during the past @xmath8gyr.   we argue that the evolution at early times is driven by ` violent'processes that removes gas from nearly half the galaxies at @xmath9 establishing the antecedants of current early - type galaxies.   the perceived constancy of, meanwhile, implies that gas is a necessary but insufficient pre - condition for star formation and that the global star - formation rate is driven by the accretion and condensation of fresh gas from the intergalactic medium.
in this review we describe a non - trivial relationship between perturbative gauge theory and gravity scattering amplitudes. at the semi - classical or tree level  , the scattering amplitudes of gravity theories in flat space can be expressed as a sum of products of well defined pieces of gauge theory amplitudes.   these relationships were first discovered by kawai, lewellen, and tye in the context of string theory, but hold more generally. in particular, they hold for standard einstein gravity. a method based on @xmath0-dimensional unitarity   can then be used to systematically construct all quantum loop corrections order - by - order in perturbation theory using as input the gravity tree amplitudes expressed in terms of gauge theory ones.   more generally, the unitarity method provides a means for perturbatively quantizing massless gravity theories without the usual formal apparatus associated with the quantization of constrained systems.   as one application, this method was used to demonstrate that maximally supersymmetric gravity is less divergent in the ultraviolet than previously thought.   # 1_#1 _
microwave cavities with high quality factors enable coherent coupling of distant quantum systems.   virtual photons lead to a transverse exchange interaction between qubits, when they are non - resonant with the cavity but resonant with each other.   we experimentally probe the inverse scaling of the inter - qubit coupling with the detuning from a cavity mode and its proportionality to the qubit - cavity interaction strength.   we demonstrate that the enhanced coupling at higher frequencies is mediated by multiple higher - harmonic cavity modes.   moreover, in the case of resonant qubits, the symmetry properties of the system lead to an allowed two - photon transition to the doubly excited qubit state and the formation of a dark state.
we use a non - markovian generalized master equation ( gme ) to describe the time - dependent charge transfer through a parabolically confined quantum wire of a finite length coupled to semi - infinite quasi two - dimensional leads.   the quantum wire and the leads are in a perpendicular external magnetic field.   the contacts to the left and right leads depend on time and are kept out of phase to model a quantum turnstile of finite size.   the effects of the driving period of the turnstile, the external magnetic field, the character of the contacts, and the chemical potential bias on the effectiveness of the charge transfer of the turnstile are examined, both in the absence and in the presence of the magnetic field.   the interplay between the strength of the coupling and the strength of the magnetic field is also discussed.   we observe how the edge states created in the presence of the magnetic field contribute to the pumped charge.
by exploiting two acs / hst datasets separated by a temporal baseline of @xmath0 years, we have determined the relative stellar proper motions ( providing membership ) and the absolute proper motion of the galactic globular cluster m71.   the absolute proper motion has been used to reconstruct the cluster orbit within a galactic, three - component, axisymmetric potential.   m71 turns out to be in a low latitude disk - like orbit inside the galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. since large differential reddening is known to affect this system, we took advantage of near - infrared, ground - based observations to re - determine the cluster center and density profile from direct star counts.   the new structural parameters turn out to be significantly different from the ones quoted in the literature. in particular  , m71 has a core and a half - mass radii almost 50% larger than previously thought.   finally we estimate that the initial mass of m71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of x - ray sources.
the distant globular cluster palomar 13 has been found to have a very high mass - to - light ratio and its profile can be well fitted either by a king model with a tail, or with a nfw model .   this cluster may be the first case of the many clumps predicted by cdm simulations that would not be disrupted by the galactic halo potential.   we make the hypothesis that pal 13 is made of neutralinos and run the darksuspect code to estimate the high - energy photon flux due to the annihilation of neutralinos through various channels in some benchmark scenarios.   these low fluxes may be used as targets to be reached in proposals for future ground - based high altitude cerenkov telescopes.
we present a generalized analytic formalism for the inverse compton x - ray emission from hydrogen - poor supernovae and apply this framework to sn2011fe using swift - xrt, uvot and chandra observations.   we characterize the optical properties of sn2011fe in the swift bands and find them to be broadly consistent with a `` normal '' sn ia, however, no x - ray source is detected by either xrt or chandra.   we constrain the progenitor system mass loss rate @xmath0 ( @xmath1 c.l. ) for wind velocity @xmath2.   our result rules out symbiotic binary progenitors for sn  2011fe and argues against roche - lobe overflowing subgiants and main sequence secondary stars _   if _ @xmath3 of the transferred mass is lost at the lagrangian points.   regardless of the density profile, the x - ray non - detections are suggestive of a clean environment ( @xmath4 ) for @xmath5 cm around the progenitor site.   this is either consistent with the bulk of material being confined within the binary system or with a significant delay between mass loss and supernova explosion.   we furthermore combine x - ray and radio limits from chomiuk et al.   2012 to constrain the post shock energy density in magnetic fields. finally, we searched for the shock breakout pulse using gamma - ray observations from the interplanetary network and find no compelling evidence for a supernova - associated burst.   based on the compact radius of the progenitor star we estimate that the shock break out pulse was likely not detectable by current satellites.
the very high energy radiation telescope array ( veritas ) is a system of four imaging cherenkov telescopes currently under construction at kitt peak, arizona, usa. the first telescope has been in operation at the mt.   hopkins basecamp since january 2005.   we present here detailed monte carlo simulations of the telescope response to extensive air showers.   the energy threshold for this stand - alone telescope is calculated to be 150 gev at trigger level, the @xmath0-ray trigger rate is 22 @xmath0s / min.   image parameter distributions, and the quality of gamma - hadron discrimination are calculated and show good agreement with distributions from observations of background cosmic rays and high - energy gamma - rays from the crab nebula and markarian 421.   the energy spectrum of the crab is reconstructed as @xmath1 m@xmath2s@xmath3tev@xmath3.
the radial velocity experiment ( rave ) is a large wide - field spectroscopic stellar survey of the milky way. over the period 2003 - 2013, 574,630 spectra for 483,330 stars   have been amassed at a resolution of r=7500 in the ca - triplet region of 8410 - 8795. wavelength coverage and resolution   are thus comparable to that anticipated from the gaia rvs.   derived data products of rave include radial velocities, stellar parameters, chemicals abundances for mg, al, si, ca, ti, fe, and ni, and absorption measures based on the diffuse interstellar bands ( dib ) at 8620.   since more than 290000 rave targets are drawn from the tycho-2 catalogue, rave will be an interesting prototype for the anticipated full gaia data releases, in particular when combined with the early gaia data releases, which contain astrometry but not yet stellar parameters and abundances.
astro - f is the second japanese space mission for infrared astronomy and is scheduled to be launched into a sun - synchronous polar orbit by the japanese m - v rocket in february 2004.   astro - f has a cooled 67 cm telescope with two focal plane instruments : one is the far - infrared surveyor ( fis ) and the other is the infrared camera ( irc ).    the main purpose of fis is to perform the all - sky survey with 4 photometric bands in the wavelength range of 50 - 200 @xmath0 m.   the advantages of the fis survey over the iras survey are ( 1 ) higher spatial resolution ( @xmath1 at 50 - 110 @xmath0 m and @xmath2 at 110 - 200 @xmath0 m ) and ( 2 ) better sensitivity by one to two orders of magnitude  . the fis survey will provide the next generation far - infrared survey catalogs, which will be ideal inputs for observations by first.   the other instrument, irc, will make deep imaging and low - resolution spectroscopic observations in the spectral range of @xmath3 m.   the irc will make large - area surveys with its wide field of view ( @xmath4 ), and will be complementary with the first observations at longer wavelengths.
we present an exact many - body theory of ultracold fermionic gases for the bose - einstein condensation ( bec ) regime of the bec - bcs crossover.   this is a purely fermionic approach which treats explicitely and systematically the dimers formed in the bec regime as made of two fermions.   we consider specifically the zero temperature case and calculate the first terms of the expansion of the chemical potential in powers of the density @xmath0.   we derive first the mean - field contribution, which has the expected standard expression when it is written in terms of the dimer - dimer scattering length @xmath1.   we go next in the expansion to the lee - huang - yang order, proportional to @xmath2.   we find the far less obvious result that it retains also the same expression in terms of @xmath1 as for elementary bosons.   the composite nature of the dimers appears only in the next term proportional to @xmath3.
previous research has highlighted the importance of strong heterogeneity for the successful evolution of cooperation in games governed by pairwise interactions.   here we determine to what extent this is true for games governed by group interactions.   we therefore study the evolution of cooperation in the public goods game on the square lattice, the triangular lattice and the random regular graph, whereby the payoffs are distributed either uniformly or exponentially amongst the players by assigning to them individual scaling factors that determine the share of the public good they will receive.   we find that uniformly distributed public goods are more successful in maintaining high levels of cooperation than exponentially distributed public goods.   this is not in agreement with previous results on games governed by pairwise interactions, indicating that group interactions may be less susceptible to the promotion of cooperation by means of strong heterogeneity as originally assumed, and that the role of strongly heterogeneous states should be reexamined for other types of games.
integrability of a square billiard is spontaneously broken as it rotates about one of its corners.   the system becomes quasi - integrable where the invariant tori are broken with respect to a certain parameter, @xmath0 where e is the energy of the particle inside the billiard and @xmath1 is the angular frequency of rotation of billiard.   we study the system classically and quantum mechanically in view of obtaining a correspondence in the two descriptions.   classical phase space in poincar surface of section shows transition from regular to chaotic motion as the parameter @xmath2 is decreased. in the quantum counterpart,   the spectral statistics shows a transition from poisson to wigner distribution as the system turns chaotic with decrease in @xmath2.   the wavefunction statistics however show breakdown of time - reversal symmetry as @xmath2 decreases.   keywords : nonlinear dynamics, chaos, quantum chaos.
x - ray transition radiation can be used to measure the lorentz factor of relativistic particles.   standard transition radiation detectors ( trds ) typically incorporate thin plastic foil, foam, or fiber radiators and gas - filled x - ray detectors, and are sensitive up to @xmath0.   to reach lorentz factors up to @xmath1, thicker, denser radiators can be used, which consequently produce x - rays of harder energies ( @xmath2 kev ). at these energies,   scintillator detectors are more efficient in detecting the hard x - rays, and compton scattering of the x - rays out of the path of the particle becomes important. the compton scattering can be utilized to separate the transition radiation from the ionization background spatially.   the use of conducting metal foils is predicted to yield enhanced signals compared to standard nonconducting plastic foils of the same dimensions.   we have designed and built an inorganic scintillator - based compton scatter trd optimized for high lorentz factors and exposed it to high energy electrons at the cern sps.   we present the results of the accelerator tests and comparisons to simulations, demonstrating 1 ) the effectiveness of the compton scatter trd approach ; 2 ) the performance of conducting aluminum foils ; and 3 ) the ability of a trd to measure energies approximately an order of magnitude higher than previously used in very high energy cosmic ray studies.   transition radiation, scintillator detectors, compton scattering, cosmic rays 95.55.vj, 29.40.mc, 07.87.+v
we report the results of a 1998 july _ beppo_sax  observation of a field in the small magellanic cloud ( smc ) which led to the discovery of @xmath0345s pulsations in the x  ray flux of saxj0103.27209.   the _ beppo_sax  x  ray spectrum is well fit by an absorbed power   law with photon index @xmath01.0 plus a black body component with @xmath1=0.11kev.   the unabsorbed luminosity in the 210 kev energy range is @xmath01.2@xmath210@xmath3ergs@xmath4. in a very recent _ chandra _   observation the 345s pulsations are also detected.   the available period measurements provide a constant period derivative of 1.7syr@xmath4 over the last three years making saxj0103.27209  one of the most rapidly spinning  up x  ray pulsars known.   the _ beppo_sax  position ( 30  uncertainty radius ) is consistent with that of the _ einstein _  source 2e0101.57225   and the _ rosat _  source rxj0103.27209.   this source was detected at a luminosity level of few 10@xmath510@xmath3ergs@xmath4 in all datasets of past x  ray missions since 1979.   the _ rosat _   hri and _ chandra _  positions are consistent with that of a m@xmath6=14.8 be spectral type star already proposed as the likely optical counterpart of 2e0101.57225.   we briefly report and discuss photometric and spectroscopic data carried out at the eso telescopes two days before the _ beppo_sax  observation
we propose a way of generating optical lattices embedded in photonic crystals. by setting up   extended modes in photonic crystals, ultracold atoms can be mounted in different types of field intensity distributions. this novel way of constructing optical lattices can be used to produce more elaborate periodic potentials by manufacturing appropriate geometries of photonic crystals. we exemplify this with a square lattice and comment on the possibility of using geometries with defects.
speden is a computer program that reconstructs the electron density of single particles from their x - ray diffraction patterns, using a single - particle adaptation of the holographic method in crystallography.   ( szoke, a., szoke, h., and somoza, j.r., 1997.   acta cryst.   a53, 291 - 313. ) the method, like its parent, is unique that it does not rely on `` back '' transformation from the diffraction pattern into real space and on interpolation within measured data.   it is designed to deal successfully with sparse, irregular, incomplete and noisy data.   it is also designed to use prior information for ensuring sensible results and for reliable convergence.   this article describes the theoretical basis for the reconstruction algorithm, its implementation and quantitative results of tests on synthetic and experimentally obtained data.   the program could be used for determining the structure of radiation tolerant samples and, eventually, of large biological molecular structures without the need for crystallization.   szoke    chapman    szoke    marchesini    noy    he    howells    weierstall    spence    speden is a computer program that reconstructs the electron density of single particles from their x - ray diffraction patterns, using an adaptation of the holographic method in crystallography.   it is designed to deal successfully with sparse, irregular, incomplete and noisy data.
the motion of a test particle in the gravitational field of a non - spherical source endowed with both mass and mass quadrupole moment is investigated when a test radiation field is also present.   the background is described by the erez - rosen solution, which is a static spacetime belonging to the weyl class of solutions to the vacuum einstein s field equations, and reduces to the familiar schwarzschild solution when the quadrupole parameter vanishes.   the radiation flux has a fixed but arbitrary ( non - zero ) angular momentum.   the interaction with the radiation field is assumed to be thomson - like, i.e., the particles absorb and re - emit radiation, thus suffering for a friction - like drag force.   such an additional force is responsible for the poynting - robertson effect, which is well established in the framework of newtonian gravity and has been recently extended to the general theory of relativity.   the balance between gravitational attraction, centrifugal force and radiation drag leads to the occurrence of equilibrium circular orbits which are attractors for the surrounding matter for every fixed value of the interaction strength.   the presence of the quadrupolar structure of the source introduces a further degree of freedom : there exists a whole family of equilibrium orbits parametrized by the quadrupole parameter, generalizing previous works.   this scenario is expected to play a role in the context of accretion matter around compact objects.       non - spherical sources  mass quadrupole moment  radiation drag
in this paper, we continue the work begun in a previous article.   we compute, in the formalism of local composite operators, the value of the asymmetry in the dimension two condensate for finite temperatures.   we find a positive value for the asymmetry, which disappears when the temperature is increased.   we also compute the value of the full dimension two condensate for higher temperatures, and we find that it decreases in abolute value, finally disappearing for sufficiently high temperature  . we also comment on the temperature dependence of the electric and magnetic components of the condensate seperately.   we compare our results with the corresponding lattice date found by chernodub and ilgenfritz.
a new model of population dynamics on lattices is proposed.   the model consists of players on lattice points, each of which plays the rsp game with neighboring players.   each player chooses the next hand from the hand of the neighboring player with the maximum point.   the model exhibits a steady pattern with pairs of vortices and sinks on the triangular lattice.   it is shown that the stationary vortex is due to the frustrations on the triangular lattice.   a frustration is the three - sided situation where each of the three players around a triangle chooses the rock, the scissors and the paper, respectively.        triangular lattice, rsp game, population dynamics, vortex
we explore how the spiral spin(sp ) state, a spin singlet known to accompany fully - polarized ferromagnetic ( f ) states in the hubbard model, is related with the f state in the thermodynamic limit using the density matrix renormalization group and exact diagonalization.   we first obtain an indication that when the f state is the ground state the sp state is also eligible as the ground state in that limit.   we then follow the general argument by koma and tasaki [ j. stat. phys. *   76 *, 745 ( 1994 ) ] to find that : ( i ) the sp state possesses a kind of order parameter.   ( ii ) although the sp state does not break the su(2 ) symmetry in finite systems, it does so in the thermodynamic limit by making a linear combination with other states that are degenerate in that limit.   we also calculate the one - particle spectral function and dynamical spin and charge susceptibilities for various 1d finite - size lattices.   we find that the excitation spectrum of the sp state and the f state is almost identical.   our present results suggest that the sp and the f states are equivalent in the thermodynamic limit.   these properties may be exploited to determine the magnetic phase diagram from finite - size studies.    2
the lhc experiments have great potential in discovering many possible new particles up to the tev scale.   the significance calculation of an observation of a physics signal with known location and shape is no longer valid when either the location or the shape of the signal is unknown.   we find the current lhc significance calculation of new physics is over - estimated and strongly depends on the specifics of the method and the situation it applies to.   we describe general procedures for significance calculation and comparing different search schemes.   a new method uses maximum likelihood fits with floating parameters and scans the parameter space for the best fit to the entire sample.   we find that the new method is significantly more sensitive than current method and is insensitive to the exact location of the new physics signal we search.   0.0 mm 0.0 mm 5 mm 170 mm 220 mm 0.0 mm
in a previous paper a method was developed to subtract the interactions due to periodically replicated charges ( or other long - range entities ) in one spatial dimension.   the method constitutes a generalized `` electrostatic layer correction '' ( * elc * ) which adapts any standard 3d summation method to slab - like conditions. here   the implementation of the layer correction is considered in detail for the standard ewald ( * ew3dlc * ) and the * p3 m * mesh ewald ( * p3mlc * ) methods. in particular   this method offers a strong control on the accuracy and an improved computational complexity of @xmath0 for mesh - based implementations.   we derive anisotropic ewald error formulas and give some fundamental guidelines for optimization.   a demonstration of the accuracy, error formulas and computation times for typical systems is also presented.
we present the results of detailed n - body simulations of clusters moving in a realistic milky way ( mw ) potential.   the strong interaction with the bulge and the disk of the galaxy leads to the formation of tidal tails, emanating from opposite sides of the cluster.   some characteristic features in the morphology and orientation of these streams are recognized and intepreted.   the tails have a complex morphology, in particular when the cluster approaches its apogalacticon, showing multiple `` arms '' in remarkable similarity to the structures observed around ngc 288 and willman 1.   + actually, the tails are generally good tracers of the cluster path quite far from the cluster center ( @xmath0@xmath1 tidal radii ), while on the smaller scale they are mainly pointing in the direction of the galaxy center.   in particular, the orientation of the inner part of the tails is highly correlated to the cluster orbital phase and to the local orbital angular acceleration.   this implies that, in general, the orbital path can not be estimated directly from the orientation of the tails, unless a sufficient large field around the cluster is available.
recent work has demonstrated that there is a tight correlation between the mass of a black hole and the velocity dispersion of the bulge of its host galaxy.   we show that the model of kauffmann & haehnelt, in which bulges and supermassive black holes both form during major mergers, produces a correlation between @xmath0 and @xmath1 with slope and scatter comparable to the observed relation. in the model,   the @xmath2 relation is significantly tighter than the correlation between black hole mass and bulge luminosity or the correlation between bulge luminosity and velocity dispersion.   there are two reasons for this : i ) the gas masses of bulge progenitors depend on the velocity dispersion but not on the formation epoch of the bulge, whereas the stellar masses of the progenitors depend on both ; ii ) mergers between galaxies move black holes along the observed @xmath3 relation, even at late times when the galaxies are gas - poor and black holes grow mainly by merging of pre - existing black holes. we conclude that the small scatter in the observed @xmath2 relation is consistent with a picture in which bulges and black holes form over a wide range in redshift.    black hole physics  galaxies : formation  galaxies : nuclei quasars : general.
building on the recent progress in solving chern - simons - matter theories in the planar limit, we compute the scaling dimensions of a large class of disorder ( `` monopole '' ) operators in @xmath0 chern - simons - fermion theories at all t hooft couplings. we find that the lowest - dimension operator of this sort has dimension @xmath1.   we comment on the implications of these results to analyzing maps of fermionic disorder operators under 3d bosonization.    `   su - itp-15/16 `    * disorder operators in chern - simons - fermion theories *    ore radievi    _ stanford institute for theoretical physics and department of physics + stanford university + stanford, ca 94305 - 4060, usa _   + ` djordje@stanford.edu ` +
on 2010 october 13, the apollo type 20-meter asteroid 2010 tb54 passed within 6.1 lunar distances from the earth. on the same date, but 11.4 hours earlier, exactly at 02:52:32 ut, the sky over central poland was illuminated by @xmath0 magnitude pf131010 ciechanw fireball. the trajectory and orbit of the fireball was computed using multi - station data of _ polish fireball network ( pfn)_. the results indicate that the orbit of the meteoroid which caused the pf131010 fireball is similar to the orbit of 2010 tb54 asteroid and both bodies may be related. moreover, two days before appearance of ciechanw fireball another small asteroid denoted as 2010 sx11 passed close to the earth - moon system.   its orbit is even more similar to the orbit of ciechanw fireball parent body than in case of 2010 tb54.   + the pf131010 ciechanw entered earth s atmosphere with the velocity of @xmath1 km / s and started to shine at height of @xmath2 km.   clear deceleration started after first three seconds of flight, and the terminal velocity of the meteor was only @xmath3 km / s at height of @xmath4 km.   such a low value of terminal velocity indicates that fragments with total mass of around 2 kg could survive the atmospheric passage and cause fall of the meteorites.   the predicted area of possible meteorite impact is computed and it is located near grabowo village south of ostroka city.       meteorites, meteors, meteoroids, asteroids
in this article, we explore the kinematics of timelike geodesic congruences in warped five dimensional bulk spacetimes, with and without thick or thin branes. beginning with geodesic flows in the randall  sundrum ads ( anti de sitter ) geometry without and with branes we find analytical expressions for the expansion scalar and comment on the effects of including thin branes on its evolution.   later, we move on to congruences in more general warped bulk geometries with a cosmological thick brane and a time - dependent extra dimensional scale. using analytical expressions for the velocity field, we interpret the expansion, shear and rotation ( esr ) along the flows, as functions of the extra dimensional coordinate. the evolution of a cross - sectional area orthogonal to the congruence, as seen from a local observer s point of view, is also shown graphically.   finally, the raychaudhuri and geodesic equations in backgrounds with a thick brane are solved numerically in order to figure out the role of initial conditions ( prescribed on the esr ) and spacetime curvature on the evolution of the esr.
recently, vision - based advanced driver assist systems have gained broad interest. in this work, we investigate free - space detection, for which we propose to employ a fully convolutional network ( fcn ). we show that this fcn can be trained in a _ self - supervised _ manner and achieve similar results compared to training on manually annotated data, thereby reducing the need for large manually annotated training sets. to this end,   our self - supervised training relies on a stereo - vision disparity system, to automatically generate ( weak ) training labels for the color - based fcn.   additionally, our self - supervised training facilitates _   online _ training of the fcn instead of offline.   consequently, given that the applied fcn is relatively small, the free - space analysis becomes highly adaptive to any traffic scene that the vehicle encounters.   we have validated our algorithm using publicly available data and on a new challenging benchmark dataset that is released with this paper.   experiments show that the online training boosts performance with @xmath0 when compared to offline training, both for @xmath1 and @xmath2.
a joint characterisation of the observability and controllability of a particular kind of discrete system has been developed.   the key idea of the procedure can be reduced to a correct choice of the sampling sequence.   this freedom, owing to the arbitrary choice of the sampling instants, is used to improve the sensitivity of system observability and controllability, by exploiting an adequate geometric structure.   some qualitative examples are presented for illustrative purposes.
the properties of the thermal abelian color - magnetic monopoles in the maximally abelian gauge are studied in the deconfinement phase of the lattice @xmath0 gluodynamics. to check universality of the monopole properties we employ the tadpole improved symanzik action.   the simulated annealing algorithm combined with multiple gauge copies is applied for fixing the maximally abelian gauge to avoid effects of gribov copies.   we compute the density, interaction parameters, thermal mass and chemical potential of the thermal abelian monopoles in the temperature range between @xmath1 and @xmath2. in comparison with earlier findings our results for these quantities   are improved either with respect to effects of gribov copies or with respect to lattice artifacts.
classical cepheids are primary distance indicators playing a fundamental role in the calibration of the extragalactic distance scale. the possible dependence of their characteristic period - luminosity ( pl ) relation on chemical composition is still debated in the literature, and the behaviour of these pulsators at very low metallicity regimes is almost unexplored. in order to derive constraints on the application of the period - luminosity relation at low metal abundances  , we investigate the properties of the few ultra - low metallicity ( @xmath0 ) cepheids recently discovered in the blue compact dwarf galaxy izw18. to this purpose   we have computed an updated and extended set of nonlinear convective models for @xmath1 and @xmath2, spanning a wide range of stellar masses, and taking into account the evolutionary constraints for selected luminosity levels. as a result we are able to predict the topology of the instability strip, the variations of all the relevant quantities along the pulsation cycle, including the morphology of the light curves, the theoretical period - luminosity - color, period - wesenheit and period - luminosity relations at such a low metallicity. for each of these relations   we provide the appropriate coefficients for fundamental mode pulsators with z=0.0004. by comparing these results with the properties of more metal rich cepheids   we find that the synthetic pl relations for @xmath1 are steeper than at higher z, but similar to the @xmath3 ones, thus suggesting a leveling off of the metallicity effect towards the lowest zs.
measuring spectral distortions of the cosmic microwave background ( cmb ) is attracting considerable attention as a probe of high energy particle physics in the cosmological context, since pixie and prism have recently been proposed. in this paper,   cmb distortions due to resonant conversions between cmb photons and light axion like particles ( alps ) are investigated, motivated by the string axiverse scenario which suggests the presence of a plenitude of light axion particles.   since these resonant conversions depend on the strength of primordial magnetic fields, constraints on cmb distortions can provide an upper limit on the product of the photon - alp coupling constant @xmath0 and the comoving strength of primordial magnetic fields @xmath1. potentially feasible constraints from pixie / prism can set a limit @xmath2 for alp mass @xmath3.   although this result is not a direct constraint on @xmath0 and @xmath1, it is significantly tighter than the product of the current upper limits on @xmath0 and @xmath1.
using data with the suzaku xis and hxd, spectral studies of short bursts from the soft gamma repeater sgr0501@xmath04516 were performed. in total,   32 bursts were detected during the @xmath160 ks of observation conducted in the 2008 august activity. excluding the strongest one, the remaining 31 bursts showed an average 240 kev fluence of @xmath2 erg@xmath3.   a 140 kev spectrum summed over them leaves significant positive residuals in the hxd - pin band with @xmath4/d.o.f.   = 74/50, when fitted with a two - blackbody function. by adding a power law model,   the fit became acceptable with @xmath4/d.o.f.   = 56/48, yielding a photon index of @xmath5.   this photon index is comparable to @xmath6 @xcite for the persistent emission of the same object obtained with suzaku.   the two - blackbody components showed very similar ratios, both in the temperature and the emission radii, to those comprising the persistent emission.   however, the power - law to two - blackbody flux ratio was possibly higher than that of the persistent emission at 2.6@xmath7 level. based on these measurements, average wide - band properties of these relatively weak bursts are compared with those of the persistent emission.
we study experimentally the thermal fluctuations of energy input and dissipation in a harmonic oscillator driven out of equilibrium, and search for fluctuation relations.   we study transient evolution from the equilibrium state, together with non equilibrium steady states.   fluctuations relations are obtained experimentally for both the work and the heat, for the stationary and transient evolutions.   a stationary state fluctuation theorem is verified for the two time prescriptions of the torque. but a transient fluctuation theorem is satisfied for the work given to the system but not for the heat dissipated by the system in the case of linear forcing.   experimental observations on the statistical and dynamical properties of the fluctuation of the angle, we derive analytical expressions for the probability density function of the work and the heat.   we obtain for the first time an analytic expression of the probability density function of the heat.   agreement between experiments and our modeling is excellent.
we examine the question of whether the formal expressions of equilibrium statistical mechanics can be applied to time independent non - dissipative systems that are not in true thermodynamic equilibrium and are nonergodic. by assuming the phase space   may be divided into time independent, locally ergodic domains, we argue that within such domains the relative probabilities of microstates are given by the standard boltzmann weights.   in contrast to previous energy landscape treatments, that have been developed specifically for the glass transition, we do not impose an a priori knowledge of the inter - domain population distribution. assuming that these domains are robust with respect to small changes in thermodynamic state variables we derive a variety of fluctuation formulae for these systems.   we verify our theoretical results using molecular dynamics simulations on a model glass forming system.   non - equilibrium transient fluctuation relations are derived for the fluctuations resulting from a sudden finite change to the system s temperature or pressure and these are shown to be consistent with the simulation results.   the necessary and sufficient conditions for these relations to be valid are that the domains are internally populated by boltzmann statistics and that the domains are robust.   the transient fluctuation relations thus provide an independent quantitative justification for the assumptions used in our statistical mechanical treatment of these systems.
we present the results of a numerical study on the effects of metal enrichment and metal cooling on galaxy formation and cosmic star formation ( sf ) history using cosmological hydrodynamic simulations.   we find following differences in the simulation with metal cooling when compared to the run without it : ( 1 ) the cosmic star formation rate ( sfr ) is enhanced by about 50 & 20% at @xmath0 & 3, respectively ; ( 2 ) the gas mass fraction in galaxies is lower ; ( 3 ) the total baryonic mass function ( gas + star ) at @xmath1 does not differ significantly, but shows an increase in the number of relatively massive galaxies at @xmath0 ; ( 4 ) the baryonic mass fraction of intergalactic medium ( igm ) is reduced at @xmath2 due to more efficient cooling and gas accretion onto galaxies.   our results suggest that the metal cooling enhances the galaxy growth by two different mechanisms : ( 1 ) increase of sf efficiency in the local interstellar medium ( ism ), and ( 2 ) increase of igm accretion onto galaxies.   the former process is effective throughout most of the cosmic history, while the latter is effective only at @xmath2 when the igm is sufficiently enriched by metals owing to feedback.   method : numerical  galaxies : evolution  galaxies : formation  galaxies : high redshift  galaxies : mass function  cosmology : theory
in this paper we consider the collision of spinning holes using first order perturbation theory of black holes ( teukolsky formalism ). with these results ( along with ones, published in the past )   one can predict the properties of the gravitational waves radiated from the late stage inspiral of two spinning, equal mass black holes.   also we note that the energy radiated by the head - on collision of two spinning holes with spins ( that are equal and opposite ) aligned along the common axis is more than the case in which the spins are perpendicular to the axis of the collision.
we present and discuss the development of an unconditionally stable algorithm used to solve the evolution equations of the phase field crystal ( pfc ) model.   this algorithm allows for an arbitrarily large algorithmic time step. as the basis for our analysis of the accuracy of this algorithm, we determine an effective time step in fourier space.   we then compare our calculations with a set of representative numerical results, and demonstrate that this algorithm is an effective approach for the study of the pfc models, yielding a time step effectively 180 times larger than the euler algorithm for a representative set of material parameters. as the pfc model is just a simple example of a wide class of density functional theories,   we expect this method will have wide applicability to modeling systems of considerable interest to the materials modeling communities.    and    unconditionally stable, phase field crystal model    05.10.-a, 02.60.cb, 64.75.+g, 81.15.aa
we present an unbiased method for evaluating the ranges of ages and metallicities which are allowed by the photometric properties of the stellar populations that dominate the light of early - type galaxies in clusters.   the method is based on the analysis of morphologically - classified early - type galaxies in @xmath0 clusters at redshifts @xmath1 and in the nearby coma cluster using recent stellar population synthesis models that span a wide range of metallicities.   we confirm that metallicity effects must play a role in the origin of the slope of the color - magnitude relation for cluster early - type galaxies.   we show, however, that the small scatter of the color - magnitude relation out to redshifts @xmath2 does not formally imply a common epoch of major star formation for all early - type galaxies. instead  , it requires that galaxies assembling more recently be on average more metal - rich than older galaxies of similar luminosity.   regardless of the true ages and metallicities of early - type galaxies within the allowed range, their photometric properties and the implied strengths of several commonly used spectral indices are found to be consistent with _ apparently _ passive evolution of the stellar populations.   also, the implied dependence of the mass - to - light ratio on galaxy luminosity is consistent with the observed trend.   the results of our unbiased analysis define the boundaries in age and metallicity that must be satisfied by theoretical studies aimed at explaining the formation and evolution of early - type galaxies in clusters.    0.5truecm    1truecm    ( accepted for publication in the _ astrophysical journal _ )
we apply the effective potential analytic continuation ( epac ) method to the calculation of real time quantum correlation functions involving operators nonlinear in the position operator @xmath0. for a harmonic system   the epac method provides the exact correlation function at all temperature ranges, while the other quantum dynamics methods, the centroid molecular dynamics and the ring polymer molecular dynamics, become worse at lower temperature. for an asymmetric anharmonic system,   the epac correlation function is in very good agreement with the exact one at @xmath1.   when the time increases from zero, the epac method gives good coincidence with the exact result at lower temperature.   finally, we propose a simplified version of the epac method to reduce the computational cost required for the calculation of the standard effective potential.
effective field theories are the most general tool for the description of low energy phenomena. they are universal and systematic : they can be formulated for any low energy systems we can think of and offer a clear guide on how to calculate predictions with reliable error estimates, a feature that is called power counting. these properties can be easily understood in wilsonian renormalization, in which effective field theories are the low energy renormalization group evolution of a more fundamental perhaps unknown or unsolvable high energy theory. in nuclear physics   they provide the possibility of a theoretically sound derivation of nuclear forces without having to solve quantum chromodynamics explicitly.   however there is the problem of how to organize calculations within nuclear effective field theory : the traditional knowledge about power counting is perturbative but nuclear physics is not. yet   power counting can be derived in wilsonian renormalization and there is already a fairly good understanding of how to apply these ideas to non - perturbative phenomena and in particular to nuclear physics. here   we review a few of these ideas, explain power counting in two - nucleon scattering and reactions with external probes and hint at how to extend the present analysis beyond the two - body problem.
we study diffusion and consensus based optimization of a sum of unknown convex objective functions over distributed networks.   the only access to these functions is through stochastic gradient oracles, each of which is only available at a different node, and a limited number of gradient oracle calls is allowed at each node. in this framework, we introduce a convex optimization algorithm based on the stochastic gradient descent ( sgd ) updates. particularly, we use a carefully designed time - dependent weighted averaging of the sgd iterates, which yields a convergence rate of @xmath0 after @xmath1 gradient updates for each node on a network of @xmath2 nodes.   we then show that after @xmath1 gradient oracle calls, the average sgd iterate achieves a mean square deviation ( msd ) of @xmath3.   this rate of convergence is optimal as it matches the performance lower bound up to constant terms.   similar to the sgd algorithm, the computational complexity of the proposed algorithm also scales linearly with the dimensionality of the data.   furthermore, the communication load of the proposed method is the same as the communication load of the sgd algorithm.   thus, the proposed algorithm is highly efficient in terms of complexity and communication load.   we illustrate the merits of the algorithm with respect to the state - of - art methods over benchmark real life data sets and widely studied network topologies.    distributed processing, convex optimization, online learning, diffusion strategies, consensus strategies.
the transport properties of molten lif - yf@xmath0 mixtures have been studied by pulsed field gradient nuclear magnetic resonance spectroscopy, potentiometric experiments, and molecular dynamics simulations.   the calculated diffusion coefficients and electric conductivities compare very well with the measurements across a wide composition range.   we then extract static ( radial distribution functions, coordination numbers distributions ) and dynamic ( cage correlation functions ) quantities from the simulations.   then, we discuss the interplay between the microscopic structure of the molten salts and their dynamic properties. it is often considered that variations in the diffusion coefficient of the anions are mainly driven by the evolution of its coordination with the metallic ion ( y@xmath1 here ).   we compare this system with fluorozirconate melts and demonstrate that the coordination number is a poor indicator of the evolution of the diffusion coefficient.   instead, we propose to use the ionic bonds lifetime.   we show that the weak y - f ionic bonds in lif - yf@xmath0 do not induce the expected tendency of the fluoride diffusion coefficient to converge toward the one of yttrium cation when the content in yf@xmath0 increases.   implications on the validity of the nernst - einstein relation for estimating the electrical conductivity are discussed.
measurements of lagrangian single - point and multiple - point statistics in a quasi - two - dimensional stratifed layer system are reported.   the system consists of a layer of salt water over an immiscible layer of fluorinert and is forced electromagnetically so that mean - squared vorticity is injected at a well - defined spatial scale.   simultaneous cascades develop in which enstrophy flows predominately to small scales whereas energy cascades, on average, to larger scales.   lagrangian velocity correlations and one- and two - point displacements are measured for random initial conditions and for initial positions within topological centers and saddles.   the behavior of these quantities can be understood in terms of the trapping characteristics of long - lived centers, the slow motion near strong saddles, and the rapid fluctuations outside of either centers or saddles.
h.e.s.s. observed tev blazar pks 2155304 in a strong flare state in 2006 july.   the tev flux varied on timescale as short as a few minutes, which sets strong constraints on the properties of the emission region. by use of the synchrotron self - compton model, we found that models with the bulk lorentz factor @xmath0, the size of the emission region @xmath1 cm, and magnetic field @xmath2 g explain the observed spectral energy distribution and the flare timescale @xmath3 a few minutes.   this model with a large value of @xmath4 accounts for the emission spectrum not only in the tev band but also in the x - ray band.   the major cooling process of electrons / positrons in the jet is inverse compton scattering off synchrotron photons.   the energy content of the jet is highly dominated by particle kinetic energy over magnetic energy.
special relativistic and strong gravity effects are clearly seen in x - ray energy spectra from agn.   most important here are the broad profiles of the fe k@xmath0 line observed in a large fraction of sources.   these indicate that x - ray generation and reprocessing takes place very close to the central black hole. here   we explore consequences of such effects on x - ray variability.   we perform computations of a possible quasi - periodic signal from a keplerian motion of primary x - ray source.   we also study in some details the light - bending model of variability of the x - ray reprocessed component, extending previous work on the subject.
resonant ( elastic ) soft x - ray scattering ( rsxs ) offers a unique element, site, and valence specific probe to study spatial modulations of charge, spin, and orbital degrees of freedom in solids on the nanoscopic length scale.   it can not only be used to investigate single crystalline materials.   this method also enables to examine electronic ordering phenomena in thin films and to zoom into electronic properties emerging at buried interfaces in artificial heterostructures. during the last 20 years  , this technique, which combines x - ray scattering with x - ray absorption spectroscopy, has developed into a powerful probe to study electronic ordering phenomena in complex materials and furthermore delivers important information on the electronic structure of condensed matter.   this review provides an introduction to the technique, covers the progress in experimental equipment, and gives a survey on recent rsxs studies of ordering in correlated electron systems and at interfaces.   ( some figures in this article are in colour only in the electronic version )    dated :..
we present current theories about the structure of space and time, where the building blocks are some fundamental entities ( yes - no experiment, quantum processes, spin net - work, preparticles ) that do not presuppose the existence of space and time.   the relations among these objects are the base for a pregeometry of discrete character, the continuous limit of which gives rise to the physical properties of the space and time.
we study the notion of hierarchy in the context of visualizing textual data and navigating text collections. a formal framework for `` hierarchy ''   is given by an ultrametric topology.   this provides us with a theoretical foundation for concept hierarchy creation.   a major objective is _ scalable _ annotation or labeling of concept maps.   serendipitously we pursue other objectives such as deriving common word pair ( and triplet ) phrases, i.e., word 2- and 3-grams.   we evaluate our approach using ( i ) a collection of texts, ( ii ) a single text subdivided into successive parts ( for which we provide an interactive demonstrator ), and ( iii ) a text subdivided at the sentence or line level. while detailing a generic framework,   a distinguishing feature of our work is that we focus on _ locality _ of hierarchic structure in order to extract semantic information.   * categories and subject descriptors : * h.5 ( information interfaces and presentation ), i.5.3 ( clustering ), h.5.2 ( user interfaces ), i.7.2 ( document preparation ), h.3 ( information storage and retrieval )
we study the effects of strong coupling of a localized state charge to one - dimensional electronic channels out of equilibrium. while the state of this charge and the coupling strengths determine the scattering phase shifts in the channels,   the nonequilibrium partitioning noise induces the tunneling transitions to the localized state.   the strong coupling leads to a nonperturbative backaction effect which is manifested in the orthogonality catastrophe and the fermi - edge singularity in the transition rates.   we predict an unusually pronounced manifestation of the non - gaussian component of noise that breaks the charge symmetry, resulting in a nontrivial shape, and a shift of the position of the tunneling resonance.
we study the nucleon at finite temperature using bethe - salpeter equation ( bse ) where it is considered as a bound state of a scalar - diquark and a quark.   the interaction between the diquark and the quark is taken as an exchange quark. the constituent quark and diquark substructures are considered momentum and temperature dependent based on the lattice qcd and dynamical chiral symmetry breaking ( dcsb ).   the kernel interaction modification with temperature is approximated using the mixed representation in the imaginary time formalism and then we adopt an adiabatic ( instantaneous ) approximation after evaluating the matsubara frequencies sum.   the results of bse are compared with those for mit bag model.   we argue the bag pressure is a temperature dependent and it decreases smoothly with temperature to be consistent with the results for bse.   furthermore, the nucleon bound state obtained by bse ceases to exist just below the critical temperature and this indicates that the nucleon deconfines to its constituent quarks at the critical temperature.   the nucleon mass decreases with temperature as @xmath0 where @xmath1 and @xmath2 and this suggests @xmath3 for mit bag.
we study the chemical bonds of small palladium clusters pd@xmath0 ( @xmath19 ) saturated by hydrogen atoms using electronic stress tensor.   our calculation includes bond orders which are recently proposed based on the stress tensor.   it is shown that our bond orders can classify the different types of chemical bonds in those clusters.   in particular, we discuss pd   h bonds associated with the h atoms with high coordination numbers and the difference of h   h bonds in the different pd clusters from viewpoint of the electronic stress tensor.   the notion of  pseudo - spindle structure " is proposed as the region between two atoms where the largest eigenvalue of the electronic stress tensor is negative and corresponding eigenvectors forming a pattern which connects them.   * electronic stress tensor analysis of hydrogenated palladium clusters *   .45 in    kazuhide ichikawa@xmath2, ayumu wagatsuma@xmath2, pawe szarek@xmath3, + chenggang zhou@xmath4, hansong cheng@xmath5 and akitomo tachibana@xmath6   .45 in    _ @xmath2department of micro engineering, kyoto university, kyoto 606 - 8501, japan + @xmath3wrocaw university of technology, institute of physical and theoretical chemistry, + wybrzee wyspiaskiego 27, 50 - 370 wrocaw, poland + @xmath7sustainable energy laboratory, china university of geosciences wuhan, + wuhan 430074, china p.r.   + @xmath8department of chemistry, national university of singapore, singapore + _   .45 in e -
in this article we provide a general analysis of canonical quantization for polaritons in dispersive and dissipative electromagnetic inhomogeneous media.   we compare several approaches based either on the huttner barnett model [ b. huttner, s. m. barnett, phys.   rev.   a * 46 *, 4306 ( 1992 ) ] or the green function, langevin noise method [ t. gruner, d.-   g.   welsch, phys.   rev. a * 53 *, 1818 ( 1996 ) ] which includes only material oscillators as fundamental variables.   we show that in order to preserve unitarity, causality and time symmetry one must necessarily include with an equal footing both electromagnetic modes and material fluctuations in the evolution equations.   this becomes particularly relevant for all nanophotonics and plasmonics problems involving spatially localized antennas or devices.
we develop a complete analytical description of the time evolution of squeezed states of a charged particle under the fock - darwin hamiltonian and a time - dependent electric field.   this result generalises a relation obtained by infeld and plebaski for states of the one - dimensional harmonic oscillator.   we relate the evolution of a state - vector subjected to squeezing to that of state which is not subjected to squeezing and for which the time - evolution under the simple harmonic oscillator dynamics is known ( e.g. an eigenstate of the hamiltonian ).   a corresponding relation is also established for the wigner functions of the states, in view of their utility in the analysis of cold - ion experiments. in an appendix  , we compute the response functions of the fd hamiltonian to an external electric field, using the same techniques as in the main text.
we describe a semi - empirical atomic basis extended hckel theoretical ( eht ) technique that can be used to calculate bulk bandstructure, surface density of states, electronic transmission and interfacial chemistry of various materials within the same computational platform.   we apply this method to study multiple technologically important systems, starting with carbon - nanotubes ( cnt ) and their interfaces in this paper, and silicon - based heterostructures in our follow - up paper.   we find that when it comes to quantum transport through interesting, complex heterostructures, the hckel bandstructure offers a fair and practical compromise between orthogonal tight - binding theories ( otb ) with limited transferability between environments under large distortion, and density functional theories ( dft ) that are computationally quite expensive for the same purpose.
a compact, quasi-4@xmath0 position sensitive silicon array, tiara, designed to study direct reactions induced by radioactive beams in inverse kinematics is described here.   the transfer and inelastic all - angle reaction array ( tiara ) consists of 8 resistive charge division detectors forming an octagonal barrel around the target and a set of double - sided silicon - strip annular detectors positioned at each end of the barrel.   the detector was coupled to the @xmath1-ray array exogam and the spectrometer vamos at the ganil laboratory to demonstrate the potential of such an apparatus with radioactive beams.   the @xmath2n(d, p)@xmath3n reaction, well known in direct kinematics, has been carried out in inverse kinematics for that purpose.   the observation of the @xmath3n ground state and excited states at 7.16 and 7.86 mev is presented here as well as the comparison of the measured proton angular distributions with dwba calculations. transferred _   l_-values are in very good agreement with both theoretical calculations and previous experimental results obtained in direct kinematics.    position sensitive silicon detectors, nucleon transfer reactions, radioactive beams, inverse kinematics
i point to an interesting similarity in the radio and the soft x - ray light curves between the november 2009 outburst of the x - ray binary aquila  x-1 and some solar flares.   the ratio of the soft x - ray and radio luminosities of aquila  x-1 in that outburst is also similar to some weak solar flares, and so is the radio spectrum near 8  ghz.   based on these, as well as on some other recent studies that point to some similar properties of accretion disk coronae and stellar flares, such as ratio of radio to x - ray luminosities ( laor & behar 2008 ), i speculate that the soft x - ray outburst of aquila  x-1 was related to a huge magnetic flare from its disk corona.
spectral diagnostic features formed in the solar chromosphere are few and difficult to interpret  they are neither formed in the optically thin regime nor in local thermodynamic equilibrium ( lte ). to probe the state of the chromosphere, both from observations and theory  , it is therefore necessary with modeling.   i discuss both traditional semi - empirical modeling, numerical experiments illustrating important ingredients necessary for a self - consistent theoretical modeling of the solar chromosphere and the first results of such models.
we study spherically symmetric thin - shell wormholes in a string cloud background in ( 3 + 1)-dimensional spacetime.   the amount of exotic matter required for the construction, the traversability and the stability under radial perturbations, are analyzed as functions of the parameters of the model. besides, in the appendices a non perturbative approach to the dynamics and a possible extension of the analysis to a related model are briefly discussed.   .25 in
the success of product quantization ( pq ) for fast nearest neighbor search depends on the exponentially reduced complexities of both storage and computation with respect to the codebook size.   recent efforts have been focused on employing sophisticated optimization strategies, or seeking more effective models.   residual quantization ( rq ) is such an alternative that holds the same property as pq in terms of the aforementioned complexities.   in addition to being a direct replacement of pq, hybrids of pq and rq can yield more gains for approximate nearest neighbor search.   this motivated us to propose a novel approach to optimizing rq and the related hybrid models. with an observation of the general randomness increase in a residual space  , we propose a new strategy that jointly learns a local transformation per residual cluster with an ultimate goal to reduce overall quantization errors.   we have shown that our approach can achieve significantly better accuracy on nearest neighbor search than both the original and the optimized pq on several very large scale benchmarks.
the fermi flare advocate ( also known as gamma - ray sky watcher, fa - gsw ) service provides for a daily quicklook analysis and review of the high - energy gamma - ray sky seen by the fermi gamma - ray space telescope.   the duty offers alerts for potentially new gamma - ray sources, interesting transients and relevant flares. a public weekly digest containing the main highlights about the gev gamma - ray sky   is published in the web - based fermi sky blog. during the first 3 years of all - sky survey,   more than 150 astronomical telegrams, several alerts to the tev cherenkov telescopes, and targets of opportunity to swift and other observatories have been distributed.   this increased the rate of simultaneous multi - frequency observing campaigns and the level of international cooperation.   many gamma - ray flares from blazars ( like the extraordinary outbursts of 3c 454.3, intense flares of pks 1510 - 089, 4c 21.35, pks 1830 - 211, ao 0235 + 164, pks 1502 + 106, 3c 279,   3c 273, pks 1622 - 253 ), short / long flux duty cycles, unidentified transients near the galactic plane ( like j0910 - 5041, j0109 + 6134, the galactic center region ), flares associated to galactic sources ( like the crab nebula, the nova v407 cyg, the microquasar cyg x-3 ), emission of the quiet and active sun, were observed by fermi and communicated by fa - gsws.
the lagrangian dynamics of the velocity gradient tensor * a * in isotropic and homogeneous turbulence depend on the joint action of the self - streching term and the pressure hessian.   existing closures for pressure effects in terms of * a * are unable to reproduce one important statistical role played by the anisotropic part of the pressure hessian, namely the redistribution of the probabilities towards enstrophy production dominated regions. as a step towards elucidating the required properties of closures, we study several synthetic velocity fields and how well they reproduce anisotropic pressure effects.   it is found that synthetic ( i ) gaussian, ( ii ) multifractal and ( iii ) minimal turnover lagrangian map ( mtlm ) incompressible velocity fields reproduce many features of real pressure fields that are obtained from numerical simulations of the navier stokes equations, including the redistribution towards enstrophy - production regions.   the synthetic fields include both spatially local, and nonlocal, anisotropic pressure effects.   however, we show that the local effects appear to be the most important ones : by assuming that the pressure hessian is local in space, an expression in terms of the hessian of the second invariant @xmath0 of the velocity gradient tensor can be obtained.   this term is found to be well correlated with the true pressure hessian both in terms of eigenvalue magnitudes and eigenvector alignments.
this paper reviews the historic of _ chalearn looking at people _ ( lap ) events.   we started in 2011 ( with the release of the first kinect device ) to run challenges related to human action / activity and gesture recognition.   since then we have regularly organized events in a series of competitions covering all aspects of visual analysis of humans.   so far we have organized more than 10 international challenges and events in this field.   this paper reviews associated events, and introduces the chalearn lap platform where public resources ( including code, data and preprints of papers ) related to the organized events are available.   we also provide a discussion on our main findings and perspectives of chalearn lap activities.
prompt neutrino fluxes due to the interactions of high - energy cosmic rays with the earth s atmosphere are backgrounds in the search for high - energy neutrinos of galactic or extra - galactic origin performed by very large volume neutrino telescopes.   we summarize our predictions for prompt neutrinos, showing their basic features as emerging from the calculation in a qcd framework capable of describing recent charm data from the large hadron collider.
the availability of new data sources on human mobility is opening new avenues for investigating the interplay of social networks, human mobility and dynamical processes such as epidemic spreading. here   we analyze data on the time - resolved face - to - face proximity of individuals in large - scale real - world scenarios.   we compare two settings with very different properties, a scientific conference and a long - running museum exhibition.   we track the behavioral networks of face - to - face proximity, and characterize them from both a static and a dynamic point of view, exposing differences and similarities.   we use our data to investigate the dynamics of a susceptible - infected model for epidemic spreading that unfolds on the dynamical networks of human proximity.   the spreading patterns are markedly different for the conference and the museum case, and they are strongly impacted by the causal structure of the network data. a deeper study of the spreading paths shows that the mere knowledge of static aggregated networks would lead to erroneous conclusions about the transmission paths on the dynamical networks.
i study the effect of scalar and spin - orbit absorption potentials, in the production of a nonzero sivers - like asymmetry in hadron - hadron high energy collisions ( drell - yan and single spin asymmetries ). a basic model is built for the intrinsic state of a quark in the projectile hadron.   s - wave and p - wave 2-component states are considered. before the hard event  , this quark is subject to absorbing mean fields simulating interactions with a composite target.   the relevant interaction terms are found to be the imaginary diagonal spin - orbit ones.   spin rotating terms, and scalar absorption, seem not to be decisive. for @xmath0 @xmath1 0 the found sivers asymmetry vanishes, while at larger @xmath0 its qualitative dependence on @xmath0, @xmath2 follows the usual trends met in available models and parameterizations. given the present - day knowledge of the considered phenomenological interactions, it is not possible to establish whether the related sivers - like asymmetry is a leading twist - one.    high energy hadron - hadron scattering, sivers asymmetry, spin - orbit forces.
we investigate laplacians on supercritical bond - percolation graphs with different boundary conditions at cluster borders. the integrated density of states of the dirichlet laplacian is found to exhibit a lifshits tail at the lower spectral edge, while that of the neumann laplacian shows a van hove asymptotics, which results from the percolating cluster. at the upper spectral edge  , the behaviour is reversed.    and    laplacian, percolation, integrated density of states
the content of hickson compact groups in the southern hemisphere is measured using data from the parkes all - sky survey ( hipass ), and dedicated observations using the narrow band filter on the multibeam instrument on the parkes telescope.   the expected mass of these groups was estimated using the luminosity, diameter and morphological types of the member galaxies, calibrated from published data. taking careful account of non - detection limits,   the results show that the compact group population that has been detected by these observations has an content similar to that of galaxies in the reference field sample.   the upper limits for the undetected groups lie within the normal range ; improvement of these limits will require a large increase in sensitivity.   = 2em    = 15.5 cm = 22.6 cm = -1.0 cm = 0.5 cm = 0.5 cm    @xmath0school of physics, university of melbourne, victoria, australia 3010 + affiliated with the australia telescope national facility, csiro + @xmath1school of physics, university of melbourne, victoria, australia 3010 + @xmath2nsf mps distinguished research fellow, australia telescope national facility, epping, new south wales, australia 1710 + @xmath3department of physics, university of queensland, queensland, australia 4072 +    * keywords : * galaxies : evolution - galaxies : interactions - methods : observational
a broad range of membrane proteins display anomalous diffusion on the cell surface.   different methods provide evidence for obstructed subdiffusion and diffusion on a fractal space, but the underlying structure inducing anomalous diffusion has never been visualized due to experimental challenges.   we addressed this problem by imaging the cortical actin at high resolution while simultaneously tracking individual membrane proteins in live mammalian cells.   our data confirm that actin introduces barriers leading to compartmentalization of the plasma membrane and that membrane proteins are transiently confined within actin fences.   furthermore, superresolution imaging shows that the cortical actin is organized into a self - similar meshwork.   these results present a hierarchical nanoscale picture of the plasma membrane.
i examine simple tests for the presence of accretion disks in agn - changes of surface brightness with viewing angle, changes of colour temperature with luminosity, and behaviour during variability.   agn observations pass the first two tests but fail the third, unless there is some previously unobserved source of heating - the `` ghost in the machine ''.
we present a model for separator reconnection due to an isolated reconnection process.   separator reconnection is a process which occurs in the neighbourhood of a distinguished field line ( the separator ) connecting two null points of a magnetic field.   it is, for example, important for the dynamics of magnetic flux at the dayside magnetopause and in the solar corona.   we find that, above a certain threshold, such a reconnection process generates new separators which leads to a complex system of magnetic flux tubes connecting regions of previously separated flux.   our findings are consistent with the findings of large numbers of separators in numerical simulations.   we discuss how to measure and interpret the reconnection rate in a configuration with multiple separators.
we investigate here the genericity and stability aspects for naked singularities and black holes that arise as the final states for a complete gravitational collapse of a spherical massive matter cloud.   the form of the matter considered is a general _ type i _   matter field, which includes most of the physically reasonable matter fields such as dust, perfect fluids and such other physically interesting forms of matter widely used in gravitation theory.   we first study here in some detail the effects of small pressure perturbations in an otherwise pressure - free collapse scenario, and examine how a collapse evolution that was going to the black hole endstate would be modified and go to a naked singularity, once small pressures are introduced in the initial data.   this allows us to understand the distribution of black holes and naked singularities in the initial data space.   collapse is examined in terms of the evolutions allowed by einstein equations, under suitable physical conditions and as evolving from a regular initial data.   we then show that both black holes and naked singularities are generic outcomes of a complete collapse, when genericity is defined in a suitable sense in an appropriate space.   # 1#2
approaches from statistical physics are applied to investigate the structure of network models whose growth rules mimic aspects of the evolution of the world - wide web.   we first determine the degree distribution of a growing network in which nodes are introduced one at a time and attach to an earlier node of degree @xmath0 with rate @xmath1.   very different behaviors arise for @xmath2, @xmath3, and @xmath4.   we also analyze the degree distribution of a heterogeneous network, the joint age - degree distribution, the correlation between degrees of neighboring nodes, as well as global network properties.   an extension to directed networks is then presented. by tuning model parameters to reasonable values,   we obtain distinct power - law forms for the in - degree and out - degree distributions with exponents that are in good agreement with current data for the web.   finally, a general growth process with independent introduction of nodes and links is investigated.   this leads to independently growing sub - networks that may coalesce with other sub - networks.   general results for both the size distribution of sub - networks and the degree distribution are obtained.
we introduce a growing network evolution model with nodal attributes.   the model describes the interactions between potentially violent @xmath0 and non - violent @xmath1 agents who have different affinities in establishing connections within their own population versus between the populations.   the model is able to generate all stable triads observed in real social systems. in the framework of rate equations theory  , we employ the mean - field approximation to derive analytical expressions of the degree distribution and the local clustering coefficient for each type of nodes.   analytical derivations agree well with numerical simulation results.   the assortativity of the potentially violent network qualitatively resembles the connectivity pattern in terrorist networks that was recently reported.   the assortativity of the network driven by aggression shows clearly different behavior than the assortativity of the networks with connections of non - aggressive nature in agreement with recent empirical results of an online social system.   networks, complex systems, rate equation approach, two - population dynamics, stable triads, terror networks
we compute the spectral correlation function ( scf ) of @xmath0co j=10 maps of molecular cloud complexes.   the scf is a power law over approximately an order of magnitude in spatial separation in every map.   the power law slope of the scf,, its normalization,, and the spectral line width averaged over the whole map, @xmath1, are computed for all the observational maps.   the values of ,  and @xmath1 are combined to obtain empirical correlations to be used as tests for theoretical models of molecular clouds.   synthetic spectral maps are computed from different theoretical models, including solutions of the magneto - hydrodynamic ( mhd ) equations with different values of the rms mach number of the flow and stochastic models with different power spectra of the velocity field. in order to compute the radiative transfer from the mhd models it is necessary to assign the models a physical scale and a physical density. when these assignments are made according to larson type relations the best fit to the observational correlations is obtained.   unphysical stochastic models are instead ruled out by the empirical correlations.   mhd models with equipartition of magnetic and kinetic energy of turbulence do not reproduce the observational data when their average magnetic field is oriented approximately parallel to the line of sight.
an algorithm for imaginary time evolution of a fermionic projected entangled pair state ( peps ) with ancillas from infinite temperature down to a finite temperature state is presented. as a benchmark application,   it is applied to spinless fermions hopping on a square lattice subject to @xmath0-wave pairing interactions. with a tiny bias it allows to evolve the system across a high - temperature continuous symmetry - breaking phase transition.
we present an exact analytic class of solutions for a system of two membranes in eleven - dimensional supergravity.   one brane in the system is completely localized along the overall and relative transverse coordinates while the other brane in the system is localized only along the overall transverse coordinates.   the membrane configuration preserves four supersymmetries.   moreover we find some approximate solutions for the system of two membranes with a bianchi space as the overall transverse space to both membranes.   all supergravity solutions preserve 1/8 of the supersymmetry. upon dimensional reduction,   the solutions provide intersecting configurations of three d - branes in type iia supergravity.    * supergravity solutions of two m2 branes * +    a. m. ghezelbash, r. oraji   + department of physics and engineering physics, + university of saskatchewan, saskatoon, saskatchewan s7n 5e2, canada +
we report @xmath0, @xmath1, and @xmath2 photometric time series of hd  149026 spanning predicted times of transit of the saturn - mass planetary companion, which was recently discovered by sato and collaborators.   we present a joint analysis of our observations and the previously reported photometry and radial velocities of the central star.   we refine the estimate of the transit ephemeris to @xmath3 = ( 2453527.87455^{+0.00085}_{-0.00091 } ) + ( 2.87598^{+0.00012}_{-0.00017 } ) \   n$ ]. assuming that the star has a radius of @xmath4 and a mass of @xmath5, we estimate the planet radius to be @xmath6, which implies a mean density of @xmath7.   this density is significantly greater than that predicted for models which include the effects of stellar insolation and for which the planet has only a small core of solid material.   thus we confirm that this planet likely contains a large core, and that the ratio of core mass to total planet mass is more akin to that of uranus and neptune than that of either jupiter or saturn.
we consider a regular random network where each node has exactly three neighbours. ising spins at the network nodes interact antiferromagnetically along the links.   the clustering coefficient @xmath0 is tuned from zero to 1/3 by adding new links. at the same time  , the density of geometrically frustrated links increases.   we calculate the magnetic specific heat, the spin susceptibility and the edwards - anderson order parameter @xmath1 by means of the heat - bath monte carlo simulations.   the aim is the transition temperature @xmath2 dependence on the clustering coefficient @xmath0.   the results are compared with the predictions of the bethe approximation. at @xmath3,   the network is bipartite and the low temperature phase is antiferromagnetic.   when @xmath0 increases, the critical temperature falls down towards the values which are close to the theoretical predictions for the spin - glass phase.   * magnetism of frustrated regular networks *    anna maka - kraso@xmath4 and krzysztof kuakowski@xmath5    _ faculty of physics and applied computer science, agh university of science and technology, al.   mickiewicza 30, pl-30059 krakw, poland + _   @xmath6kulakowski@novell.ftj.agh.edu.pl    _   pacs numbers : 75.30.kz, 64.60.aq, 05.10.ln_    _ keywords : antiferromagnetism, spin glass, disorder, frustration, regular random networks _
we develop a complete theoretical description of photoassociative stimulated raman adiabatic passage ( stirap ) near a feshbach resonance in a thermal atomic gas.   we show that it is possible to use _ low intensity _ laser pulses to directly excite the continuum at a feshbach resonance and transfer nearly the entire atomic population to the lowest rovibrational level in the molecular ground state. in case of a broad resonance, commonly found in several diatomic alkali molecules,   our model predicts a transfer efficiency @xmath0 up to 97% for a given atom pair, and up to 70% when averaged over an atomic ensemble.   the laser intensities and pulse durations needed for optimal transfer are @xmath1 w/@xmath2 and several @xmath3s.   such efficiency compares to or surpasses currently available techniques for creating stable diatomic molecules, and the versatility of this approach simplifies its potential use for many molecular species.
this work explores fundamental modeling and algorithmic issues arising in the well - established mapreduce framework.   first, we formally specify a computational model for mapreduce which captures the functional flavor of the paradigm by allowing for a flexible use of parallelism.   indeed, the model diverges from a traditional processor - centric view by featuring parameters which embody only global and local memory constraints, thus favoring a more data - centric view.   second, we apply the model to the fundamental computation task of matrix multiplication presenting upper and lower bounds for both dense and sparse matrix multiplication, which highlight interesting tradeoffs between space and round complexity. finally, building on the matrix multiplication results, we derive further space - round tradeoffs on matrix inversion and matching.    algorithms for distributed computing ; algorithms for high performance computing ; parallel algorithms ; parallel complexity theory.
we derive the equations governing static, spherically symmetric vacuum solutions to the einstein equations, as modified by the frame - dependent effective action ( derived from trace dynamics ) that gives an alternative explanation of the origin of `` dark energy ''.   we give analytic and numerical results for the solutions of these equations, first in polar coordinates, and then in isotropic coordinates.   general features of the static case are that ( i ) there is no horizon, since @xmath0 is non - vanishing for finite values of the polar radius, and only vanishes ( in isotropic coordinates ) at the internal singularity, ( ii ) the ricci scalar @xmath1 vanishes identically, and ( iii ) there is a physical singularity at cosmological distances. the large distance singularity may be an artifact of the static restriction, since we find that the behavior at large distances is altered in a time - dependent solution using the mcvittie ansatz.
q - let is a fortran 77 code that enables a quick estimate of the gravitational lensing effects on a point- or an extended source.   the user provided input consists of the redshifts, angular positions relative to the source, mass or velocity dispersion estimate and halo type for the lens galaxies.   the considered halo types are the navarro - frenk - white and the singular isothermal sphere.   the code uses the so - called multiple lens - plane method to find the magnification and intrinsic shape of the source.   this method takes into account the multiple deflections that may arise when several mass accumulations are situated at different redshifts close to the line - of - sight.   the q - let code is applied to the recently discovered supernova, sn2003es, which is likely to be of type ia as its host galaxy is classified as an elliptical.   we find that sn2003es is likely to have been significantly magnified by gravitational lensing and that this should be considered in high-@xmath0 studies if this sn is to be used to determine the cosmological parameters.   q - let was motivated by the supernova searches, where lensing can be a problem, but it can also be applied to any simple lens system where a quick estimate is wanted, e.g.  the single lens case.
for each integer @xmath0, we apply gluing methods to construct sequences of minimal surfaces embedded in the round @xmath1-sphere.   we produce two types of sequences, all desingularizing collections of intersecting clifford tori.   sequences of the first type converge to a collection of @xmath2 clifford tori intersecting with maximal symmetry along these two circles. near each of the circles, after rescaling, the sequences converge smoothly on compact subsets to a karcher - scherk tower of order @xmath2.   sequences of the second type desingularize a collection of the same @xmath2 clifford tori supplemented by an additional clifford torus equidistant from the original two circles of intersection, so that the latter torus orthogonally intersects each of the former @xmath2 tori along a pair of disjoint orthogonal circles, near which the corresponding rescaled sequences converge to a singly periodic scherk surface. the simpler examples of the first type resemble surfaces constructed by choe and soret @xcite by different methods where the number of handles desingularizing each circle is the same.   there is a plethora of new examples which are more complicated and on which the number of handles for the two circles differs.   examples of the second type are new as well.
we have generated a novel form of shear banding in a 2d foam and measured the relative magnitude of drag forces on soap films at different lubrication layers.   we injected air part way along a flowing bubble field in a narrow hele - shaw cell.   the injected air inflates bubbles as they flow by, and these bubbles form a shear band down the middle of the hele - shaw cell.   this channel appears to select a height that minimizes the total dissipation.   fitting data to a simple theoretical model, we show that the drag force on a soap film in contact with the wetting layer on a plate of glass is two orders of magnitude larger than the drag on a soap film in contact with another free soap film.
using the high granular calice analog hadron calorimeter ( ahcal ) a tracking algorithm capable of identifying mip - like tracks within hadronic showers is presented.   such an algorithm provides excellent tools for detector calibration and for studies of the substructure of hadronic showers.   the properties of the identified tracks are used as observables for a monte - carlo to data comparison.
under certain conditions, hg(cd)te quantum wells ( qws ) are known to realize a time - reversal symmetric, two - dimensional topological insulator phase.   its low - energy excitations are well - described by the phenomenological bernevig - hughes - zhang ( bhz ) model that interpolates between schrdinger and dirac fermion physics.   we study the polarization function of this model in random phase approximation ( rpa ) in the intrinsic limit and at finite doping. while the polarization properties in rpa of dirac and schrdinger particles are two comprehensively studied problems, our analysis of the bhz model bridges the gap between these two limits, shedding light on systems with intermediate properties.   we gain insight into the screening properties of the system and on its characteristic plasma oscillations.   interestingly, we discover two different kinds of plasmons that are related to the presence of intra- and interband excitations  . observable signatures of these plasmons are carefully analyzed in a variety of distinct parameter regimes, including the experimentally relevant ones for hg(cd)te qws.   we conclude that the discovered plasmons are observable by raman or electron loss spectroscopy.
the low energy regime of 5d braneworld models with a bulk scalar field is studied.   the setup is rather general and includes the randall - sundrum and dilatonic braneworlds models as particular cases.   we discuss the cosmological evolution of the system and conclude that, in a two brane system, the negative tension brane is generally expected to evolve towards a null warp - factor state.   this implies, for late time cosmology, that both branes end up interacting weakly.   we also analyze the observational constraints imposed by solar - system and binary - pulsar tests on the braneworld configuration.   this is done by considering the small deviations produced by the branes on the 4d gravitational interaction between bodies in the same brane. using these constraints   we show that the geometry around the braneworld is strongly warped, and that both branes must be far apart.
we report on the distribution of metallicities, , for very metal - poor stars in the halo of the galaxy.   although the primary information on the nature of the metallicity distribution function ( mdf ) is obtained from the two major recent surveys for metal - poor stars, the hk survey of beers and collaborators, and the hamburg / eso survey of christlieb and collaborators, we also discuss the mdf derived from the publicly available database of stellar spectra and photometry contained in the third data release of the sloan digital sky survey ( sdss dr-3 ).   even though the sdss was not originally planned as a stellar survey, significant numbers of stars have been observed to date   dr-3 contains spectroscopy for over 70,000 stars, at least half of which are suitable for abundance determinations.   there are as many very metal - poor (  @xmath0 ) stars in dr-3 as have been obtained from all previous survey efforts combined.   we also discuss prospects for significant expansion of the list of metal - poor stars to be obtained from the recently funded extension of the sdss, which includes the project segue : sloan extension for galactic understanding and exploration.
the status of present theoretical description of very high energy hadronic interactions is reviewed.   the impact of new results of accelerator and cosmic ray experiments on hadronic interaction model constructions is discussed in detail.   special attention is payed to remaining uncertainties in model extrapolations into the ultra - high energy domain, in particular, concerning model predictions for the muon component of extensive air showers.   new promising theoretical approaches are outlined and future experimental prospects are discussed.
we construct magnetostatic models of coronal loops in which the thermodynamics of the loop is fully consistent with the shape and geometry of the loop.   this is achieved by treating the loop as a thin, compact, magnetic fibril that is a small departure from a force - free state.   the density along the loop is related to the loop s curvature by requiring that the lorentz force arising from this deviation is balanced by buoyancy.   this equilibrium, coupled with hydrostatic balance and the ideal gas law, then connects the temperature of the loop with the curvature of the loop without resorting to a detailed treatment of heating and cooling.   we present two example solutions : one with a spatially invariant magnetic bond number ( the dimensionless ratio of buoyancy to lorentz forces ) and the other with a constant radius of curvature of the loop s axis.   we find that the density and temperature profiles are quite sensitive to curvature variations along the loop, even for loops with similar aspect ratios.
we introduce the stochastic domino cellular automaton model exhibiting avalanches.   depending of the choice of the parameters, the model covers wide range of properties : various types of exponential and long tail ( up to inverse - power ) distributions of avalanches are observed.   the stationary state of automaton is described by a set of nonlinear discrete equations derived in an exact way from elementary combinatorial arguments.   these equations allow to derive formulas explaining both various exponential and inverse power distributions relating them to values of the parameters.   the exact relations between the state variable of the model ( moments ) are derived in two ways : from direct arguments and from the set of equations.   excellent agreement of the obtained analytical results with numerical simulations is observed.
transporting solids of different sizes is an essential process in the evolution of protoplanetary disks and planet formation.   large solids are supposed to drift inward ; high - temperature minerals found in comets are assumed to have been transported outward. from low - gravity experiments on parabolic flights we studied the light - induced erosion of dusty bodies caused by a solid - state greenhouse effect and photophoresis within a dust bed s upper layers.   tje gravity levels studied were 0.16@xmath0, 0.38@xmath0, 1@xmath0, and 1.7@xmath0.   the light flux during the experiments was 12 @xmath1 2 kw m@xmath2 and the ambient pressure was 6 @xmath1 0.9 mbar.   light - induced erosion is strongly gravity dependent, which is in agreement with a developed model.   in particular for small dusty bodies ( ( sub)-planetesimals ), efficient erosion is possible at the optically thin inner edges of protoplanetary disks.   light - induced erosion prevents significant parts of a larger body from moving too close to the host star and be being subsequently accreted.   the small dust produced continues to be subject to photophoresis and is partially transported upward and outward over the surface of the disk ; the resulting small dust particles observed over the disk s lifetime.   the fraction of eroded dust participates in subsequent cycles of growth during planetesimal formation.   another fraction of dust might be collected by a body of planetary size if this body is already present close to the disk edge. either way,   light induced erosion is an efficient recycling process in protoplanetary disks.
we propose two fabry - perot cavities, each pumped through both the mirrors, positioned in line as _ a toy model _ of the gravitational - wave ( gw ) detector free from displacement noise of the test masses.   it is demonstrated that the displacement noise of cavity mirrors as well as laser noise can be completely excluded in a proper linear combination of the cavities output signals.   we show that in low - frequency approximation ( gravitational wave length @xmath0 is much greater than distance @xmath1 between mirrors @xmath2 ) the decrease of response signal is about @xmath3, i.e. signal is stronger than the one of the interferometer recently proposed by s.  kawamura and y.  chen @xcite.
this paper considers the collision avoidance problem in a multi - agent multi - obstacle framework.   the originality in solving this intensively studied problem resides in the proposed geometrical view combined with differential flatness for trajectory generation and b - splines for the flat output parametrization. using some important properties of these theoretical tools   we show that the constraints can be validated at all times.   exact and sub - optimal constructions of the collision avoidance optimization problem are provided.   the results are validated through extensive simulations over standard autonomous aerial vehicle dynamics.   obstacle avoidance, flat trajectory, b - spline basis, mip ( mixed - integer programming ), uav ( unmanned aerial vehicle ).
a multi - wavelength spatial and temporal analysis of solar high energy electrons is conducted using the august 20, 2002 flare of an unusually flat ( @xmath0 ) hard x - ray spectrum.   the flare is studied using rhessi, h@xmath1, radio, trace, and mdi observations with advanced methods and techniques never previously applied in the solar flare context. a new method to account for x - ray compton backscattering in the photosphere ( photospheric albedo ) has been used to deduce the primary x - ray flare spectra.   the mean electron flux distribution has been analysed using both forward fitting and model independent inversion methods of spectral analysis.   we show that the contribution of the photospheric albedo to the photon spectrum modifies the calculated mean electron flux distribution, mainly at energies below @xmath2100  kev.   the positions of the h@xmath1 emission and hard x - ray sources with respect to the current - free extrapolation of the mdi photospheric magnetic field and the characteristics of the radio emission provide evidence of the closed geometry of the magnetic field structure and the flare process in low altitude magnetic loops. in agreement with the predictions of some solar flare models,   the hard x - ray sources are located on the external edges of the h@xmath1 emission and show chromospheric plasma heated by the non - thermal electrons.   the fast changes of h@xmath1 intensities are located not only inside the hard x - ray sources, as expected if they are the signatures of the chromospheric response to the electron bombardment, but also away from them.
we present a suite of extragalactic explorations of the origins and nature of globular clusters ( gcs ) and ultra - compact dwarfs ( ucds ), and the connections between them.   an example of gc metallicity bimodality is shown to reflect underlying, distinct metal - poor and metal - rich stellar halo populations.   metallicity - matching methods are used to trace the birth sites and epochs of gcs in giant e / s0s, pointing to clumpy disk galaxies at @xmath0 for the metal - rich gcs, and to a combination of accreted and in - situ formation modes at @xmath16 for the metal - poor gcs.   an increasingly diverse zoo of compact stellar systems is being discovered, including objects that bridge the gaps between ucds and faint fuzzies, and between ucds and compact ellipticals.   many of these have properties pointing to origins as the stripped nuclei of larger galaxies, and a smoking - gun example is presented of an @xmath2  cen - like star cluster embedded in a tidal stream.
we propose a clustering - based iterative algorithm to solve certain optimization problems in machine learning, where we start the algorithm by aggregating the original data, solving the problem on aggregated data, and then in subsequent steps gradually disaggregate the aggregated data.   we apply the algorithm to common machine learning problems such as the least absolute deviation regression problem, support vector machines, and semi - supervised support vector machines.   we derive model - specific data aggregation and disaggregation procedures.   we also show optimality, convergence, and the optimality gap of the approximated solution in each iteration. a computational study is provided.
0.3 in we combine results from cdf and d  searches for a standard model higgs boson ( @xmath0 ) in  collisions at the fermilab tevatron at @xmath1  tev. with 3.0   of data analyzed at cdf, and 3.0   at d, the 95% c.l.   upper limits on higgs boson production are a factor of 1.2, 1.0 and 1.3 higher than the sm cross section for a higgs boson mass of @xmath2165, 170 and 175  gev / c@xmath3, respectively.   we exclude at 95% c.l. a standard model higgs boson of @xmath4 gev/@xmath5. based on simulation,   the ratios of the corresponding median expected upper limit to the standard model cross section are 1.2, 1.4 and 1.7. compared to the previous higgs tevatron combination, more data and refined analysis techniques   have been used.   these results extend significantly the individual limits of each experiment and provide new knowledge on the mass of the standard model higgs boson beyond the lep direct searches. + _ preliminary results _    0.5 in
we report on the _ suzaku _ observation of neutron star low - mass x - ray binary cygnus x-2 which reveals a presence of the iron k@xmath0 emission line.   the line profile shows a significant red wing.   this discovery increases the number of neutron star sources where red - skewed iron lines were observed and strongly suggests that this phenomenon is common not only in black holes but also in other types of accreting compact objects.   we examine the line profile in terms of models which attribute its production to the relativistic effects due to reflection of x - ray radiation from a cold accretion disk and also as a result of the line formation in the extended wind / outflow configuration.   both models are able to adequately represent the observed line profile.   we consider the results of line modeling in the context of subsecond variability. while we were unable to conclusively disqualify one of the models, we find that the wind paradigm has several advantages over the relativistic disk reflection model.
in this study we introduce and analyze the statistical structural properties of a model of growing networks which may be relevant to social networks. at each step a new node is added which selects @xmath0 possible partners from the existing network and joins them with probability @xmath1 by undirected edges.   the ` activity'of the node ends here ; it will get new partners only if it is selected by a newcomer.   the model produces an infinite - order phase transition when a giant component appears at a specific value of @xmath1, which depends on @xmath2.   the average component size is discontinuous at the transition.   in contrast, the network behaves significantly different for @xmath3.   there is no giant component formed for any @xmath1 and thus in this sense there is no phase transition.   however, the average component size diverges for @xmath4.   @xmath5__department of biophysics kfki research institute for particle and nuclear physics of the hungarian academy of sciences budapest, hungary _   _    @xmath6__center for complex systems studies, kalamazoo college, kalamazoo, mi 49006, usa _ _   _ @xmath7physics department, kalamazoo college, kalamazoo, mi 49006, usa _
a general and rigorous methodology to compute the quantum equilibrium isotope effect is described. unlike standard approaches  , ours does not assume separability of rotational and vibrational motions and does not make the harmonic approximation for vibrations or rigid rotor approximation for the rotations.   in particular, zero point energy and anharmonicity effects are described correctly quantum mechanically.   the approach is based on the thermodynamic integration with respect to the mass of isotopes and on the feynman path integral representation of the partition function.   an efficient estimator for the derivative of free energy is used whose statistical error is independent of the number of imaginary time slices in the path integral, speeding up calculations by a factor of @xmath0 at @xmath1 @xmath2 and more at room temperature.   we describe the implementation of the methodology in the molecular dynamics package amber 10.   the method is tested on three  sigmatropic hydrogen shift reactions. because of the computational expense, we use ab initio potentials to evaluate the equilibrium isotope effects within the harmonic approximation, and then the path integral method together with semiempirical potentials to evaluate the anharmonicity corrections.   our calculations show that the anharmonicity effects amount up to @xmath3 of the symmetry reduced reaction free energy.   the numerical results are compared with recent experiments of doering and coworkers, confirming the accuracy of the most recent measurement on 2,4,6,7,9-pentamethyl-5-(5,5-@xmath4h@xmath5)methylene-11,11a - dihydro-12_h_-naphthacene as well as concerns about compromised accuracy, due to side reactions, of another measurement on 2-methyl-10-(10,10-@xmath4h@xmath5)methylenebicyclo[4.
recently, chen _ et al.   [ new j. phys.   * 13 * ( 2011 ) 083018 ] presented experimental results, accompanied by quantum - mechanical analysis, showing that the quantum interference behavior of bell states could be simulated in a modified mach - zehnder interferometer whose inputs are pseudothermal light beams obtained by passing laser light through a rotating ground - glass diffuser.   their experiments and their theory presumed low - flux operation in which the simulated quantum interference is observed via photon - coincidence counting. we first show that the chen _   et al.   photon - coincidence counting experiments can be fully explained with semiclassical photodetection theory, in which light is taken to be a classical electromagnetic wave, and the discreteness of the electron charge leads to shot noise as the fundamental photodetection noise.   we then use semiclassical photodetection theory to show that the _ same  simulated quantum interference pattern can be observed in high - flux operation, when photocurrent cross - correlation is used instead of photon - coincidence counting. _   _ _
we present data from our investigation of the anomalous orange - colored afterglow that was seen in the gammev chameleon afterglow search ( chase ).   these data includes information about the broad band color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to and during the science operations of chase.   while differing in several details, the generic properties of the afterglow from chase are similar to luminescence seen in some vacuum compounds.   contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectors and high intensity light sources in a cryogenic environment.
in this work we investigate the dynamics of random walk processes on scale - free networks in a short to moderate time scale.   we perform extensive simulations for the calculation of the mean squared displacement, the network coverage and the survival probability on a network with a concentration @xmath0 of static traps.   we show that the random walkers remain close to their origin, but cover a large part of the network at the same time.   this behavior is markedly different than usual random walk processes in the literature. for the trapping problem   we numerically compute @xmath1, the survival probability of mobile species at time @xmath2, as a function of the concentration of trap nodes, @xmath0.   comparison of our results to the rosenstock approximation indicate that this is an adequate description for networks with @xmath3 and yield an exponential decay.   for @xmath4 the behavior is more complicated and one needs to employ a truncated cumulant expansion.
we show a relationship between the non - acyclic reidemeister torsion and a zero of the acyclic reidemeister torsion for a @xmath0-regular @xmath1 or @xmath2-representation of a knot group.   then we give a method to calculate the non - acyclic reidemeister torsion of a knot exterior.   we calculate a new example and investigate the behavior of the non - acyclic reidemeister torsion associated to a @xmath3-bridge knot and @xmath1-representations of its knot group.
the notion of @xmath0-grading on the enveloping algebra generated by products of @xmath0-deformed heisenberg algebras is introduced for @xmath0 complex number in the unit disc. within this formulation  , we consider the extension of the notion of supersymmetry in the enveloping algebra.   we recover the ordinary @xmath1 grading or grassmann parity for associative superalgebra, and a modified version of the usual supersymmetry. as a specific problem,   we focus on the interesting limit @xmath2 for which the arik and coon deformation of the heisenberg algebra allows to map fermionic modes to bosonic ones in a modified sense.   different algebraic consequences are discussed.   nithep-09 - 12 + icmpa - mpa/2009/21 +    * @xmath0-graded heisenberg algebras and deformed supersymmetries *    joseph ben geloun@xmath3 and mahouton norbert hounkonnou@xmath4    @xmath5_national institute for theoretical physics ( nithep ) _ + _ private bag x1, matieland 7602, south africa _   + @xmath6_international chair in mathematical physics and applications _ + _ ( icmpa  unesco chair ), 072 b.p.   50 cotonou, republic of benin _   + @xmath7_dpartement de mathmatiques et informatique _ + _ facult des sciences et techniques, universit cheikh anta diop, senegal _   e - mails : @xmath8bengeloun@sun.ac.za,@xmath9norbert.hounkonnou@cimpa.u
the advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems.   successful implementations face the challenge to preserve the relevant nonclassical features at the level of device operation.   a major obstacle is decoherence which is caused by interaction with the environment.   optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence.   we review here recent advances in optimal control methodology that allow for tackling typical tasks in device operation for open quantum systems and discuss examples of relaxation - optimized dynamics.   optimal control theory is also a useful tool to exploit the environment for control.   we discuss examples and point out possible future extensions.
we consider a server with large capacity delivering video files encoded in various resolutions.   we assume that the system is under saturation in the sense that the total demand exceeds the server capacity @xmath0.   in such case, requests may be rejected.   for the policies considered in this paper, instead of rejecting a video request, it is downgraded.   when the occupancy of the server is above some value @xmath1, the server delivers the video at a minimal bit rate.   the quantity @xmath2 is the bit rate adaptation threshold.   for these policies, request blocking is thus replaced with bit rate adaptation. under the assumptions of poisson request arrivals and exponential service times,   we show that, by rescaling the system, a process associated with the occupancy of the server converges to some limiting process whose invariant distribution is computed explicitly.   this allows us to derive an asymptotic expression of the key performance measure of such a policy, namely the equilibrium probability that a request is transmitted at requested bitrate.   numerical applications of these results are presented.   ''' ''   ''' ''
we develop the theory of interstellar scintillation as caused by an irregular plasma having a power - law spatial density spectrum with a spectral exponent of @xmath0 corresponding to a medium with abrupt changes in its density.   an `` outer scale '' is included in the model representing the typical scale over which the density of the medium remains uniform.   such a spectrum could be used to model plasma shock fronts in supernova remnants or other plasma discontinuities.   we investigate and develop equations for the decorrelation bandwidth of diffractive scintillations and the refractive scintillation index and compare our results with pulsar measurements.   we consider both a medium concentrated in a thin layer and an extended irregular medium. we conclude that the @xmath0 model gives satisfactory agreement for many diffractive measurements, in particular the vlbi meaurements of the structure function exponent between 5/3 and 2.   however, it gives less satisfactory agreement for the refractive scintillation index than does the kolmogorov turbulence spectrum.   the comparison suggests that the medium consists of a pervasive background distribution of turbulence embedded with randomly placed discrete plasma structures such as shocks or hii regions.   this can be modeled by a composite spectrum following the kolmogorov form at high wavenumbers and steepening at lower wavenumbers corresponding to the typical ( inverse ) size of the discrete structures.   such a model can also explain the extreme scattering events.   however, lines of sight through the enhanced scattering prevalent at low galactic latitudes are accurately described by the kolmogorov spectrum in an extended medium and do not appear to have a similar low - wavenumber steepening.
we have examined the power spectral behavior of  using approximately 1100 days of batse data.   these data have been searched for correlations between different power spectral features, and for correlations between power spectral features and energy spectral parameters derived from batse occultation analysis.
the paul scherrer institut in switzerland operates the high intensity proton accelerator facility hipa. a 590mev kinetic energy proton beam of presently up to 2.4ma is sent to target stations producing pions, muons and neutrons for fundamental and applied physics.   the beam power of 1.4mw provides the world s highest intensities of low momentum muons which can be stopped in low mass targets.   rates of surface muons of up to about @xmath0/s are being provided to various unique precision particle physics experiments.   two feasibility studies are ongoing to considerably improve the available muon beams.   the high intensity muon beamline, himb, could deliver on the order of @xmath1/s surface muons and the stopped muon cooler, mucool, aims at a gain factor of @xmath1 in phase space quality while sacrificing only less than 3 orders of magnitude in intensity for low energy @xmath2.   these beams will allow a new generation of precision physics experiments with stopped muons and muonium atoms.
coherent spin transport through bilayer graphene ( blg ) nanoflakes sandwiched between two electrodes made of single - layer zigzag graphene nanoribbon was investigated by means of landauer - buttiker formalism.   application of a magnetic field only on blg structure as a channel produces a perfect spin polarization in a large energy region.   moreover, the conductance could be strongly modulated by magnetization of the zigzag edge of ab - stacked blg, and the junction, entirely made of carbon, produces a giant magnetoresistance ( gmr ) up to @xmath0.   intestinally, gmr and spin polarization could be tuned by varying blg width and length.   generally, mr in a ab - stacked blg strongly increases ( decreases ) with length ( width ).    1 cm
the distribution of the sunspot group size ( area ) and its dependence on the level of solar activity is studied.   it is shown that the fraction of small groups is not constant but decreases with the level of solar activity so that high solar activity is largely defined by big groups.   we study the possible influence of solar activity on the ability of a realistic observer to see and report the daily number of sunspot groups.   it is shown that the relation between the number of sunspot groups as seen by different observers with different observational acuity thresholds is strongly non - linear and can not be approximated by the traditionally used linear scaling ( @xmath0factors ). the observational acuity threshold [ @xmath1 is considered to quantify the quality of each observer, instead of the traditional relative @xmath0factor.   a nonlinear @xmath2factor based on @xmath3 is proposed, which can be used to correct each observer to the reference conditions.   the method is tested on a pair of principal solar observers, wolf and wolfer, and it is shown that the traditional linear correction, with the constant @xmath0factor of 1.66 to scale wolf to wolfer, leads to an overestimate of solar activity around solar maxima.
the relative dispersion process in two - dimensional free convection turbulence is investigated by direct numerical simulation. in the inertial range  , the growth of relative separation, @xmath0, is expected as @xmath1 according to the bolgiano   obukhov scaling.   the result supporting the scaling is obtained with exit - time statistics.   detailed investigation of exit - time pdf shows that the pdf is divided into two regions, the region - i and -ii, reflecting two types of separating processes : persistent expansion and random transitions between expansion and compression of relative separation.   this is consistent with the physical picture of the self - similar telegraph model.   in addition, a method for estimating the parameters of the model are presented. comparing two turbulence cases,   two - dimensional free convection and inverse cascade turbulence, the relation between the drift term of the model and nature of coherent structures is discussed.
many early - type galaxies have been detected at wavelengths of 24 to 160  but the emission is usually dominated by heating from an agn or from the evolved stellar population. here   we present _ spitzer _ mips observations of a sample of elliptical and lenticular galaxies that are rich in cold molecular gas, and we investigate whether the mir to fir emission could be associated with star formation activity.   the 24  images show a rich variety of structures, including nuclear point sources, rings, disks, and smooth extended emission.   comparisons to matched - resolution co and radio continuum images suggest that the bulk of the 24  emission can be traced to star formation with some notable exceptions.   the 24  luminosities of the co - rich galaxies are typically a factor of 15 larger than what would be expected from the dust associated with their evolved stars.   in addition, fir / radio flux density ratios are consistent with star formation.   we conclude that the star formation rates in @xmath0 elliptical and lenticular galaxies, as inferred by other authors from uv and optical data, are roughly consistent with the molecular gas abundances and that the molecular gas is usually unstable to star formation activity.
we report two nearby high proper motion dwarfs of special interest identified using the preliminary data release of the wide - field infrared survey explorer ( wise ) and the two micron all - sky survey ( 2mass ).   wisep j191239.91 - 361516.4 has a motion of 2.1 arcseconds per year.   photometry identifies it as a mid - m dwarf.   wisep j190648.47 + 401106.8 is a spectroscopically confirmed l1 dwarf in the _ kepler mission _   field with a motion of 0.48 arcseconds per year.   the estimated distance is 17 parsecs.   both lie at relatively low galactic latitudes and demonstrate the possibility of discovering proper motion stars independently of the historic photographic sky surveys.
electronic states with non - trivial topology host a number of novel phenomena with potential for revolutionizing information technology.   the quantum anomalous hall effect provides spin - polarized dissipation - free transport of electrons, while the quantum spin hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence - free quantum computing.   we introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice mott insulators through, for instance, chemical substitution. as an example  , we apply this new approach to the natural mineral herbertsmithite.   we prove the feasibility of the proposed modifications by performing _   ab - initio _ density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models.   our results herald a new family of quantum anomalous hall and quantum spin hall insulators at affordable energy / temperature scales based on kagome lattices of transition metal ions.
the precise knowledge of the half - life of the reaction product is of crucial importance for a nuclear reaction cross section measurement carried out with the activation technique.   the cross section of the @xmath0eu(@xmath1,n)@xmath2 tb reaction has been measured recently using the activation method, however, the half - life of the 10 h isomer in @xmath2 tb has a relatively high uncertainty and ambiguous values can be found in the literature.   therefore, the precise half - life of the isomeric state has been measured and found to be t@xmath3=9.994h@xmath40.039h. with careful analysis of the systematic errors,   the uncertainty of this half - life value has been significantly reduced.   @xmath2 tb isomeric state, measured half - life, gamma - spectroscopy 23.35.+g, 23.40.-s, 25.55.-e, 27.70.+q
we treat the problem of normally ordering expressions involving the standard boson operators @xmath0, @xmath1 where @xmath2=1 $ ].   we show that a simple product formula for formal power series  essentially an extension of the taylor expansion  leads to a double exponential formula which enables a powerful graphical description of the generating functions of the combinatorial sequences associated with such functions  in essence, a combinatorial field theory.   we apply these techniques to some examples related to specific physical hamiltonians.
the effects of reservoir squeezing on the precision of parameter estimation are investigated analytically based on non - perturbation procedures.   the exact analytic quantum fisher information ( qfi ) is obtained.   it is shown that the qfi depends on the estimated parameter and its decay could be reduced by the squeezed reservoir compared with thermal ( vacuum ) reservoir, in particular, if the squeezing phase matching is satisfied.    quantum fisher information, squeezed reservoir, non - perturbative master equation
the luminous x - ray binary and black - hole candidate lmc x-1 has been observed with the rossi x - ray timing explorer ( @xmath0 ) to search for quasi - periodic oscillations ( qpo ), previously reported in its high state.   the source was observed monthly in a series of nine observations.   analysis of the temporal variations shows no evidence for qpo or other periodic changes, but correlations between the high - energy light curve and hardness of the spectrum are described.   spectral fits with two - component models demonstrate that the hardness variations come from changes in the intensity of the high - energy power - law tail.
to generate small neutrino masses radiatively, the zee - model introduces two higgs doublets and one weak - singlet charged higgs boson to its higgs sector. from analyzing the renormalization group equations, we determine the possible range of the lightest cp - even higgs boson ( @xmath0 ) mass and the higgs boson self - couplings as a function of the cut - off scale beyond which either some of the coupling constants are strong enough to invalidate the perturbative analysis or the stability of the electroweak vacuum is no longer guaranteed. using the results obtained from the above analysis  , we find that the singlet charged higgs boson can significantly modify the partial decay width of @xmath1 via radiative corrections, and its collider phenomenology can also be drastically different from that of the charged higgs bosons in the usual two - higgs - doublet models.   # 1#2#3#4#1 * # 2 * ( # 4 ) # 3    _ to appear in physical review d _
we have observed a bright flare of sgr  a * in the near infrared with the adaptive optics assisted integral field spectrometer sinfoni. within the uncertainties,   the observed spectrum is featureless and can be described by a power law.   our data suggest that the spectral index is correlated with the instantaneous flux and that both quantities experience significant changes within less than one hour.   we argue that the near infrared flares from sgr  a * are due to synchrotron emission of transiently heated electrons, the emission being affected by orbital dynamics and synchrotron cooling, both acting on timescales of @xmath0 minutes.
a recently published highly extrapolatable semiempirical shell model mass equation is shown to describe rather well the energies of several seemingly well identified @xmath0-decay chains with known end product nuclei observed in superheavy elements research.   the equation is also applied to the interpretation problem of some recent hot fusion - evaporation experiments with unknown end products and several conceivable reaction channels.   some plausible interpretations are indicated.    _   the racah institute of physics, the hebrew university of jerusalem, _    _ jerusalem 91904, israel _    pacs numbers : 21.10.dr, 21.60.cs, 27.90.+b
the theory of planetary dynamos and its applications to observed phenomena of planetary magnetism are outlined.   it is generally accepted that convection flows driven by thermal or compositional buoyancy are the most likely source for the sustenance of global planetary magnetic fields. while the existence of dynamos in electrically conducting fluid planetary cores provides constraints on properties of the latter, the lack of knowledge about time dependences of the magnetic fields and about their toroidal components together with the restricted parameter regions accessible to theory have prevented so far a full understanding of the phenomena of planetary magnetism. + * published in `` planets and moons '', t.  spohn ( ed. ), vol.   10 of series `` treatise on geophysics '', pp.  281 - 298, g.  schubert, ( gen.  ed. ), elsevier, 2007 + doi : 10.1016/b978 - 044452748 - 6.00160 - 7 *    makecaption#1#2 tempboxa*#1 : * _ _ # 2 tempboxa > to
by using the concept of negativity, we investigate entanglement in ( 1/2,1 ) mixed - spin heisenberg systems.   we obtain the analytical results of entanglement in small isotropic heisenberg clusters with only nearest - neighbor ( nn ) interactions up to four spins and in the four - spin heisenberg model with both nn and next - nearest - neighbor ( nnn ) interactions. for more spins  , we numerically study effects of temperature, magnetic fields, and nnn interactions on entanglement.   we study in detail the threshold value of the temperature, after which the negativity vanishes.
the epsilon - near - zero ( enz ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch.   here we experimentally demonstrate nonlinear control of the enz tunneling by an external field, as well as self - modulation of the transmission resonance due to the incident wave. using a waveguide section near cut - off frequency as the enz system  , we introduce a diode with tunable and nonlinear capacitance to demonstrate both of these effects.   our results confirm earlier theoretical ideas on using an enz channel for dielectric sensing, and their potential applications for tunable slow - light structures.
we investigate the short - term dynamical evolution of stellar grand - design spiral arms in barred spiral galaxies using a three - dimensional ( 3d ) @xmath0-body / hydrodynamic simulation.   similar to previous numerical simulations of unbarred, multiple - arm spirals, we find that grand - design spiral arms in barred galaxies are not stationary, but rather dynamic.   this means that the amplitudes, pitch angles, and rotational frequencies of the spiral arms are not constant, but change within a few hundred million years ( i.e. the typical rotational period of a galaxy ).   we also find that the clear grand - design spirals in barred galaxies appear _ only when _ the spirals connect with the ends of the bar.   furthermore, we find that the short - term behaviour of spiral arms in the outer regions ( @xmath1 1.52 bar radius ) can be explained by the swing amplification theory and that the effects of the bar are not negligible in the inner regions ( @xmath2 1.52 bar radius ).   these results suggest that, although grand - design spiral arms in barred galaxies are affected by the stellar bar, the grand - design spiral arms essentially originate not as bar - driven stationary density waves, but rather as self - excited dynamic patterns. we imply that a rigidly rotating grand - design spiral could not be a reasonable dynamical model for investigating gas flows and cloud formation even in barred spiral galaxies.   method : numerical  galaxies : kinematics and dynamics  galaxies : spiral  galaxies : structure
we present a detailed calculation of intensities of two - phonon and four - phonon raman peaks in graphene. writing the low - energy hamiltonian of the interaction of electrons with the crystal vibrations and the electromagnetic field from pure symmetry considerations, we describe the system in terms of just a few independent coupling constants, considered to be parameters of the theory.   the electron scattering rate is introduced phenomenologically as another parameter.   the results of the calculation are used to extract information about these parameters from the experimentally measured raman peak intensities. in particular, the raman intensities are sensitive to the electron scattering rate, which is not easy to measure by other techniques.   also, the raman intensities depend on electron - phonon coupling constants ; to reproduce the experimental results, one has to take into account renormalization of these coupling constants by electron - electron interaction.
the dynamical response of the abrikosov vortex lattice in the presence of an oscillating driving field is calculated by constructing an analytical solution of the time - dependent ginzburg - landau equation.   the solution is steady - state, and work done by the input signal is dissipated through vortex cores, mainly by scattering with phonons.   the response is nonlinear in the input signal, and is verified for consistency within the theory.   the existence of well - defined parameters to control nonlinear effects is important for any practical application in electronics, and a normalised distance from the normal - superconducting phase - transition boundary is found to be such a parameter to which the response is sensitive.   favourable comparison with nbn experimental data in the optical region is made, where the effect is in the linear regime.   predictions are put forward regarding the suppression of heating and also the lattice configuration at high frequency.
giant electric dipole resonance ( gdr ) parameters for @xmath0 decay to excited states with finite spin and temperature are compiled.   over 100 original works have been reviewed and from some 70 of which more than 300 parameter sets of hot gdr parameters for different isotopes, excitation energies, and spin regions have been extracted.   all parameter sets have been brought onto a common footing by calculating the equivalent lorentzian parameters.   the current compilation is complementary to an earlier compilation by samuel s. dietrich and barry l. berman ( at.  data nucl.   data tables * 38, 199 - 338, 1988 ) on ground - state photo - neutron and photo - absorption cross sections and their lorentzian parameters.   a comparison of the two may help shed light on the evolution of gdr parameters with temperature and spin.   the present compilation is current as of january 2006. *
we investigate strong mechanical feedback for the single - electron tunneling device coupled to an underdamped harmonic oscillator in the high - frequency case, when the mechanical energy of the oscillator exceeds the tunnel rate, and for weak coupling. in the strong feedback regime,   the mechanical oscillations oscillated by the telegraph signal from the set in their turn modify the electric current.   in contrast to the earlier results for the low frequencies, the current noise in not enhanced above the poisson value.
a three - configuration mixing calculation is performed in the context of the interacting boson model with the aim to describe recently observed collective bands built on low - lying @xmath0 states in neutron - deficient lead isotopes.   the configurations that are included correspond to the regular, spherical states as well as two - particle two - hole and four - particle four - hole excitations across the @xmath1 shell gap.
we implement slow roll reconstruction  an optimal solution to the inverse problem for inflationary cosmology  within modecode, a publicly available solver for the inflationary dynamics.   we obtain up - to - date constraints on the reconstructed inflationary potential, derived from the wmap 7-year dataset and south pole telescope observations, combined with large scale structure data derived from sdss data release 7. using modecode  in conjunction with the multinest   sampler,   we compute bayesian evidence for the reconstructed potential at each order in the truncated slow roll hierarchy. we find that the data are well - described by the first two slow roll parameters, @xmath0 and @xmath1, and that there is no need to include a nontrivial @xmath2 parameter.
we present a study of the radial velocity offsets between narrow emission lines and host galaxy lines ( stellar absorption and h  i 21-cm emission ) in seyfert galaxies with observed redshifts less than 0.043.   we find that 35% of the seyferts in the sample show  emission lines with blueshifts with respect to their host galaxies exceeding 50 km s@xmath0, whereas only 6% show redshifts this large, in qualitative agreement with most previous studies.   we also find that a greater percentage of seyfert 1 galaxies show blueshifts than seyfert 2 galaxies. using _   spatially - resolved spectra of the seyfert 2 galaxy ngc  1068 and the seyfert 1 galaxy ngc  4151, we generate geometric models of their narrow - line regions ( nlrs ) and inner galactic disks, and show how these models can explain the blueshifted  emission lines in collapsed stis spectra of these two seyferts.   we conclude that the combination of mass outflow of ionized gas in the nlr and extinction by dust in the inner disk ( primarily in the form of dust spirals ) is primarily responsible for the velocity offsets in seyfert galaxies.   more exotic explanations are not needed.   we discuss the implications of this result for the velocity offsets found in higher redshift agn.
the mesoscopic organization of complex systems, from financial markets to the brain, is an intermediate between the microscopic dynamics of individual units ( stocks or neurons, in the mentioned cases ), and the macroscopic dynamics of the system as a whole.   the organization is determined by `` communities '' of units whose dynamics, represented by time series of activity, is more strongly correlated internally than with the rest of the system.   recent studies have shown that the binary projections of various financial and neural time series exhibit nontrivial dynamical features that resemble those of the original data.   this implies that a significant piece of information is encoded into the binary projection ( i.e. the sign ) of such increments.   here, we explore whether the binary signatures of multiple time series can replicate the same complex community organization of the financial market, as the original weighted time series. we adopt a method that has been specifically designed to detect communities from cross - correlation matrices of time series data.   our analysis shows that the simpler binary representation leads to a community structure that is almost identical with that obtained using the full weighted representation.   these results confirm that binary projections of financial time series contain significant structural information.
we show that the mass function of black holes expected from the past quasar activity ( both visible and obscured ) is consistent with the number of dormant black holes found in the bulges of nearby galaxies.   the joint formation of quasars and bulges is addressed by means of an analytical model for galaxy formation, based on the hierarchical clustering of cold dark matter halos.   the model is able to reproduce the main statistical properties of both populations under the hypotheses that ( i ) star formation and quasar shining follow an anti - hierarchical order, and ( ii ) galaxy morphology and final black hole mass are determined by the same physical process.
we present results from _ xmm  newton _  observations of the obscured qso.   we find that the previously reported optical and soft x  ray counterpart positions are incorrect.   however we confirm the spectroscopic redshift of 0.176.   the optical counterpart has a k magnitude of 13.5 and an r  k colour of 5.0 and is therefore a bright extremely red object ( ero ).   the x  ray spectrum is well described by a power - law ( @xmath0 ) absorbed by an intrinsic neutral column density of @xmath1.   we find that any scattered emission contributes at most 0.5 percent to the total x  ray flux. from the optical   / near  ir colour we estimate that the active nucleus must contribute at least 50 percent of the total flux in the k band and that the ratio of extinction to x  ray absorption is @xmath2 times that expected from a galactic dust - gas ratio and extinction curve. if  were @xmath3 less luminous it would be indistinguishable from the population responsible for most of the 210 kev x  ray background.   this has important implications for the optical / ir properties of faint absorbed x  ray sources.   galaxies : active  x  rays : galaxies  x  rays : diffuse background
in this paper we give an introduction to the numerical density matrix renormalization group ( dmrg ) algorithm, from the perspective of the more general matrix product state ( mps ) formulation.   we cover in detail the differences between the original dmrg formulation and the mps approach, demonstrating the additional flexibility that arises from constructing both the wavefunction and the hamiltonian in mps form.   we also show how to make use of global symmetries, for both the abelian and non - abelian cases.
in this article, we propose an improved multiple feedback successive interference cancellation ( imf - sic ) algorithm for symbol vector detection in multiple - input multiple - output ( mimo ) spatial multiplexing systems.   the multiple feedback ( mf ) strategy in successive interference cancellation ( sic ) is based on the concept of shadow area constraint ( sac ) where, if the decision falls in the shadow region multiple neighboring constellation points will be used in the decision feedback loop followed by the conventional sic. the best candidate symbol from multiple neighboring symbols   is selected using the maximum likelihood ( ml ) criteria. however, while deciding the best symbol from multiple neighboring symbols, the sac condition may occur in subsequent layers which results in inaccurate decision. in order to overcome this limitation, in the proposed algorithm,   sac criteria is checked recursively for each layer.   this results in successful mitigation of error propagation thus significantly improving the bit error rate ( ber ) performance.   further, we also propose an ordered imf - sic ( oimf - sic ) where we use log likelihood ratio ( llr ) based dynamic ordering of the detection sequence. in oimf - sic  , we use the term dynamic ordering in the sense that the detection order is updated after every successful decision.   simulation results show that the proposed algorithms outperform the existing detectors such as conventional sic and mf - sic in terms of ber, and achieves a near ml performance.   mimo detection, spatial multiplexing, decision feedback, successive interference cancellation, bit error rate.
stellar abundances of beryllium are useful in different areas of astrophysics, including studies of the galactic chemical evolution, of stellar evolution, and of the formation of globular clusters.   determining be abundances in stars is, however, a challenging endeavor.   the two be ii resonance lines useful for abundance analyses are in the near uv, a region strongly affected by atmospheric extinction.   cubes is a new spectrograph planned for the vlt that will be more sensitive than current instruments in the near uv spectral region.   it will allow the observation of fainter stars, expanding the number of targets where be abundances can be determined. here  , a brief review of stellar abundances of be is presented together with a discussion of science cases for cubes.   in particular, preliminary simulations of cubes spectra are presented, highlighting its possible impact in investigations of be abundances of extremely metal - poor stars and of stars in globular clusters.
an accurate fitting formula is reported for the two - point correlation function @xmath0 of the dark matter halos in hierarchical clustering models.   it is valid for the linearly clustering regime, and its accuracy is about 10% in @xmath1 for the halos with mass @xmath2 where @xmath3 is the characteristic non - linear mass.   the result is found on the basis of a careful analysis for a large set of scale - free simulations with @xmath4 particles. the fitting formula has a weak explicit dependence on the index @xmath5 of the initial power spectrum, but can be equally well applied to the cold dark matter ( cdm ) cosmological models if the effective index @xmath6 of the cdm power spectrum at the scale of the halo mass replaces the index @xmath5.   the formula agrees with the analytical formula of mo & white ( mw96 ) for massive halos with @xmath7, but the mw96 formula significantly underpredicts @xmath0 for the less massive halos.   the difference between the fitting and the analytical formulae amounts to a factor @xmath8 in @xmath0 for @xmath9.   one of the most interesting applications of this fitting formula would be the clustering of galaxies since the majority of halos hosting galaxies satisfies @xmath10.   # 1*r*_#1 # 1*s*_#1 # 1|n(*r*_#1 ) # 1|n(*s*_#1 ) # 1_z(r_p#1,_#1 ) # 1(r_#1 ) # 1(s_#1 ) # 1w(r_p#1 )
we consider the jastrow pair - product wavefunction for the strongly correlated bose systems, in our case liquid helium-4.   an ansatz is proposed for the pair factors which consists of a numeric solution to a modified and parametrized pair scattering equation.   we consider a number of such simple one - variable parametrizations.   additionally, we allow for a parametrizeable cutoff of the pair factors and for the addition of a long - range phonon tail  . this approach results in the many - body wavefunctions that have between just one and three parameters.   calculation of observables is carried with the variational monte carlo method.   we find that such a simple parametrization is sufficient to produce results that are comparable in quality to the best available two - body jastrow factors for helium. for two - parameter wavefunction  , we find variational energies of @xmath0  k per particle for a system of one thousand particles.   it is also shown that short - range two - body correlations are reproduced in detail by two- and three - parameter functions.
twirl operations, which convert impure singlet states into werner states, play an important role in many schemes for entanglement purification. in this paper   we describe strategies for implementing twirl operations, with an emphasis on methods suitable for ensemble quantum information processors such as nuclear magnetic resonance ( nmr ) quantum computers.   we implement our twirl operation on a general two - spin mixed state using liquid state nmr techniques, demonstrating that we can obtain the singlet werner state with high fidelity.
we apply the nonperturbative functional renormalization group ( np - frg ) in the superfield formalism that we have developed in the preceding paper to study long - standing issues concerning the critical behavior of the random field ising model. through the introduction of an appropriate regulator and a supersymmetry - compatible nonperturbative approximation, we are able to follow the supersymmetry, more specifically the superrotational invariance first unveiled by parisi and sourlas [ phys.   rev.   lett. * 43 *, 744 ( 1979 ) ], and its spontaneous breaking along the rg flow.   breaking occurs below a critical dimension @xmath0, and the supersymmetry - broken fixed point that controls the critical behavior then leads to a breakdown of the `` dimensional reduction '' property.   we solve the np - frg flow equations numerically and determine the critical exponents as a function of dimension down to @xmath1, with a good agreement in @xmath2 and @xmath3 with the existing numerical estimates.
we use high resolution n - body / sph simulations to study the hydrodynamical interaction between the large magellanic cloud ( lmc ) and the hot halo of the milky way.   we investigate whether ram - pressure acting on the satellite s ism can explain the peculiarities observed in the hi distribution and the location of the recent star formation activity.    due to the present   nearly edge - on orientation of the disk with respect to the orbital motion, compression at the leading edge can explain the high density region observed in hi at the south - east border.   in the case of a face - on disk ( according to mastropietro et al.   2008 the lmc was moving almost face - on before the last perigalactic passage ), ram - pressure directed perpendicularly to the disk produces a clumpy structure characterized by voids and high density filaments that resemble those observed by the parkes hi survey. as a consequence of the very recent edge - on motion,   the h@xmath0 emission is mainly concentrated on the eastern side where 30 doradus and most of the supergiant shells are located, although some h@xmath0 complexes form a patchy distribution on the entire disk. in this scenario   only the youngest stellar complexes show a progression in age along the leading border of the disk.       methods : n - body simulations  hydrodynamics  galaxies : interactions  galaxies : individual : lmc
for the fermi - pasta - ulam chain, an effective hamiltonian is constructed, describing the motion of approximate, weakly localized discrete breathers traveling along the chain.   the velocity of these moving and localized vibrations can be estimated analytically as the group velocity of the corresponding wave packet.   the peierls - nabarro barrier is estimated for strongly localized discrete breathers.   michael kastner    physikalisches   institut, theoretische physik i, universitt bayreuth    95440 bayreuth, germany    jacques - alexandre sepulchre    institut non linaire de nice    1361 route des lucioles, 06560 sophia antipolis, france
an exact analytic solution has been obtained for a uniformly expanding, neutral, infinitely conducting plasma cylinder in an external uniform and constant magnetic field.   the electrodynamical aspects related to the emission and transformation of energy have been considered as well.   the results obtained can be used in analysing the recent experimental and simulation data.   plasma expansion, boundary value problem, magnetic field    03.50.de, 41.20.gz, 41.20.jb, 52.30.-q
we present a preliminary analysis of the photospheric activity of corot - exo-2a, a young g7v star accompanied by a transiting hot jupiter recently discovered by corot.   we apply spot modelling techniques developed for the analysis of the sun as a star and capable to extract from corot high precision light curves information on the variation of the total spotted area and the longitude of active regions along the 142 days of the observations.   this preliminary analysis shows that the active regions form within two active longitudes separated by about @xmath0 and rotating with periods of 4.5221 and 4.5543 days, respectively, and that the total spotted area oscillates with a period of about 28.9 days.   address = inaf - osservatorio astrofisico di catania, via s.  sofia, 78, 95123 catania, italy     address = inaf - osservatorio astrofisico di catania, via s.  sofia, 78, 95123 catania, italy     address = inaf - osservatorio astrofisico di catania, via s.  sofia, 78, 95123 catania, italy     address = inaf - osservatorio astrofisico di catania, via s.  sofia, 78, 95123 catania, italy     address = laboratoire dastrophysique de marseille, umr  6110, cnrs, universit de provence, traverse du siphon, 13376 marseille, france     address = lesia, cnrs umr  8109, observatoire de paris, 5 place j.  janssen, 92195 meudon,
high resolution molecular line observations of,,,  and  were obtained toward the starless globule  in order to investigate its kinematics and chemistry.   the hco@xmath0 and cs spectra show clear self - reversed and asymmetric profiles across the face of the globule.   the sense of the observed asymmetry is indicative of the global presence of expansion motions in the outer layers of the globule.   these motions appear to be subsonic and significantly below the escape velocity of the globule.   comparison of our observations with near - infrared extinction data indicate that the globule is gravitationally bound. taken together these considerations lead us to suggest that the observed expansion has its origin in an oscillatory motion of the outer layers of the globule which itself is likely in a quasi - stable state near hydrostatic equilibrium.   analysis of the observed linewidths of c@xmath1o  and  confirm that thermal pressure is the dominant component of the cloud s internal support.   a simple calculation suggests that the dominant mode of pulsation would be an l = 2 mode with a period of @xmath2 @xmath3 yrs.   deformation of the globule due to the large amplitude l = 2 oscillation may be responsible for the double - peaked structure of the core detected in high resolution extinction maps.   detailed comparison of the molecular - line observations and extinction data provides evidence for significant depletion of c@xmath1o  and perhaps hco@xmath0  while  may be undepleted to a cloud depth of @xmath2 40 magnitudes of visual extinction.
we study the problem of generating a test sequence that achieves maximal coverage for a reactive system under test.   we formulate the problem as a repeated game between the tester and the system, where the system state space is partitioned according to some coverage criterion and the objective of the tester is to maximize the set of partitions ( or coverage goals ) visited during the game.   we show the complexity of the maximal coverage problem for non - deterministic systems is pspace - complete, but is np - complete for deterministic systems. for the special case of non - deterministic systems with a re - initializing `` reset '' action, which represent running a new test input on a re - initialized system,   we show that the complexity is again co - np - complete.   our proof technique for reset games uses randomized testing strategies that circumvent the exponentially large memory requirement in the deterministic case.
motivated by a recent experiment directly measuring the current - phase relation ( cpr ) in graphene under the influence of a superconducting proximity effect, we here study the temperature dependence of the cpr in ballistic graphene sns josephson junctions within the the self - consistent tight - binding bogoliubov - de gennes ( bdg ) formalism. by comparing these results with the standard dirac - bdg method, where rigid boundary conditions are assumed at the s@xmath0n interfaces, we show on a crucial importance of both proximity effect and depairing by current for the cpr.   the proximity effect grows with temperature and reduces the skewness of the cpr towards the harmonic result. in short junctions ( @xmath1 )   current depairing is also important and gives rise to a critical phase @xmath2 over a wide range of temperatures and doping levels.
we consider the possibilities for obtaining information about the equation of state for quark matter by using future direct observational data on gravitational waves.   we study the nonradial oscillations of both fluid and spacetime modes of pure quark stars.   if we observe the @xmath0 and the lowest @xmath1 modes from quark stars, by using the simultaneously obtained radiation radius we can constrain the bag constant @xmath2 with reasonable accuracy, independently of the @xmath3 quark mass.
binary central stars have long been invoked to explain the vexing shapes of planetary nebulae ( pne ) despite there being scant direct evidence to support this hypothesis.   modern large - scale surveys and improved observing strategies have allowed us to significantly boost the number of known close binary central stars and estimate at least 20% of pne have close binary nuclei that passed through a common - envelope ( ce ) phase. the larger sample of post - ce nebulae appears to have a high proportion of bipolar nebulae, low - ionisation structures ( especially in sn1987a - like rings ) and polar outflows or jets.   these trends are guiding our target selection in ongoing multi - epoch spectroscopic and photometric surveys for new binaries.   multiple new discoveries are being uncovered that further strengthen the connection between post - ce trends and close binaries.   these ongoing surveys also have wider implications for understanding ce evolution, low - ionisation structure and jet formation, spectral classification of central stars, asymptotic giant branch ( agb ) nucleosynthesis and dust obscuration events in pne.
we generalize and extend the stochastic path integral formalism and action principle for continuous quantum measurement introduced in [ a. chantasri, j. dressel and a. n. jordan, phys.   rev.   a * 88 *, 042110 ( 2013 ) ], where the optimal dynamics, such as the most likely paths, is obtained by extremizing the action of the stochastic path integral. in this work, we apply exact functional methods as well as develop a perturbative approach to investigate the statistical behaviour of continuous quantum measurement.   examples are given for the qubit case.   for qubit measurement with zero qubit hamiltonian, we find analytic solutions for average trajectories and their variances while conditioning on fixed initial and final states. for qubit measurement with unitary evolution  , we use the perturbation method to compute expectation values, variances, and multi - time correlation functions of qubit trajectories in the short - time regime.   moreover, we consider continuous qubit measurement with feedback control, using the action principle to investigate the global dynamics of its most likely paths, and finding that in an ideal case, qubit state stabilization at any desired pure state is possible with linear feedback.   we also illustrate the power of the functional method by computing correlation functions for the qubit trajectories with a feedback loop to stabilize the qubit rabi frequency.
future multi - tier communication networks will require enhanced network capacity and reduced overhead. in the absence of channel state information ( csi ) at the transmitters, blind interference alignment ( bia ) and topological interference management ( tim ) can achieve optimal degrees of freedom ( dof ), minimizing network s overhead.   in addition, non - orthogonal multiple access ( noma ) can increase the sum rate of the network, compared to orthogonal radio access techniques currently adopted by 4 g networks.   our contribution is two interference management schemes, bia and a hybrid tim - noma scheme, employed in heterogeneous networks by applying user - pairing and kornecker product representation.   bia manages inter- and intra - cell interference by antenna selection and appropriate message scheduling.   the hybrid scheme manages intra - cell interference based on noma and inter - cell interference based on tim.   we show that both schemes achieve at least double the rate of tdma.   the hybrid scheme always outperforms tdma and bia in terms of degrees of freedom ( dof ). comparing the two proposed schemes,   bia achieves more dof than tdma under certain restrictions, and provides better bit - error - rate ( ber ) and sum rate perfomance to macrocell users, whereas the hybrid scheme improves the performance of femtocell users.
we used h@xmath0 - 0.1  nm and magnetic field ( at 1.56@xmath1 ) data obtained with the new solar telescope to study the origin of the disk counterparts to type ii spicules, so - called rapid blueshifted excursions ( rbes ).   the high time cadence of our chromospheric ( 10  s ) and magnetic field ( 45  s ) data allowed us to generate x - t plots using slits parallel to the spines of the rbes. these plots, along with potential field extrapolation, led us to suggest that the occurrence of rbes is generally correlated with the appearance of new, mixed or unipolar fields in close proximity to network fields.   rbes show a tendency to occur at the interface between large - scale fields and small - scale dynamic magnetic loops and thus are likely to be associated with existence of a magnetic canopy.   detection of kinked and/or inverse `` y '' shaped rbes further confirm this conclusion.
we describe different types of self - trapped optical beams carrying phase dislocations, including _ vortex solitons _ and ring - like _ soliton clusters_. we demonstrate numerically how to create such nonlinear singular beams by the interaction of several fundamental optical solitons.   mutual trapping of several solitons can be regarded as a synthesis of _ ` soliton molecules'_, and it corresponds to a transfer of an initial orbital angular momentum of a system of solitons to a spin momentum of an optical vortex.
considering the low - temperature ( @xmath0 ) and high - baryon - number - density ( @xmath1 ) region of the qcd phase diagram, we present a model for the first - order phase transition between the quark - gluon plasma ( qgp ) and the recently proposed colour superconducting phase.   we study nucleation of a droplet of the superconducting phase within the metastable qgp gas.   numerical results for the activation energy, radius and other physical parameters of the droplets, at various temperatures, densities and gap parameters, are given.   we have estimated the latent heat of the phase transition. in the @xmath2 plane, we are able to demarcate the region of the superconducting phase.   pacs numbers : 12.38.mh, 12.38.aw, 26.60.+c, 64.60.qb    _ keywords _ : quark - gluon plasma, qcd phase transition, colour superconductivity, droplet formation, diquark   ''' ''    0.3 cm e - mail : bhalerao@theory.tifr.res.in, bhaduri@smiley.physics.mcmaster.ca
the fraction of substructures required to account for anomalous flux ratios in gravitational lens systems appears to be higher than that predicted in the standard cold dark matter cosmology.   we present a possible alternative route to anomalous flux ratios from lens galaxy environments.   we consider the compound lens system such that a lens galaxy lie in a group or cluster, and estimate the contribution of substructures in the group / cluster to the fraction using an analytic model of substructures.   we find that the contribution becomes dominant when the impact parameter of the lens is less than @xmath0 of the virial radius of the group / cluster.   this indicates that the environmental effect can partly explain the high incidence of anomalous flux ratios.    -  .65 in        cosmology : theory  dark matter  gravitational lensing
scientific motivations for ultra- and extremely high energy neutrino astronomy are considered.   sources and expected fluxes of ehe / uhe neutrinos are briefly discussed.   operating and planned experiments on astrophysical neutrino detection are reviewed focusing on deep underwater / ice cherenkov neutrino telescopes.   igor  sokalski
the structural and electronic properties of si(335)-au surface decorated with pb atoms are studied by means of density - functional theory.   the resulting structural model features pb atoms bonded to neighboring si and au surface atoms, forming monoatomic chain located 0.2 nm above the surface.   the presence of pb chain leads to a strong rebonding of si atoms at the step edge.   the fact that pb atoms occupy positions in the middle of terrace is consistent with stm data, and also confirmed by simulated stm images.   the calculated band structure clearly shows one - dimensional metallic character.   the calculated electronic bands remain in very good agreement with photoemission data.
according to the may - wigner stability theorem, increasing the complexity of a network inevitably leads to its destabilization, such that a small perturbation will be able to disrupt the entire system.   one of the principal arguments against this observation is that it is valid only for random networks, and therefore does not apply to real - world networks, which presumably are structured.   here we examine how the introduction of small - world topological structure into networks affect their stability.   our results indicate that, in structured networks, the parameter values at which the stability - instability transition occurs with increasing complexity is identical to that predicted by the may - wigner criteria. however, the nature of the transition, as measured by the finite - size scaling exponent, appears to change as the network topology transforms from regular to random, with the small - world regime as the cross - over region.   this behavior is related to the localization of the largest eigenvalues along the real axis in the eigenvalue plain with increasing regularity in the network.   pacs numbers : 89.75.-k, 05.10.-a, 02.70.hm, 87.23.-n
this paper presents a formalized proof of a discrete form of the jordan curve theorem.   it is based on a hypermap model of planar subdivisions, formal specifications and proofs assisted by the coq system.   fundamental properties are proven by structural or noetherian induction : genus theorem, euler s formula, constructive planarity criteria. a notion of ring of faces   is inductively defined and a jordan curve theorem is stated and proven for any planar hypermap.    jean - franois dufourd
the striking broad emission line spectroscopic appearance of wolf - rayet ( wr ) stars has long defied analysis, due to the extreme physical conditions within their line and continuum forming regions. recently, model atmosphere studies have advanced sufficiently to enable the determination of stellar temperatures, luminosities, abundances, ionizing fluxes and wind properties  . the observed distributions of nitrogen ( wn ) and carbon ( wc ) sequence wr stars in the milky way and in nearby star forming galaxies are discussed ; these imply lower limits to progenitor masses of @xmath025, 40, 75 @xmath1 for hydrogen - depleted ( he - burning ) wn, wc, and h - rich ( h - burning ) wn stars, respectively.   wr stars in massive star binaries permit studies of wind - wind interactions and dust formation in wc systems.   they also show that wr stars have typical masses of 1025@xmath1, extending up to 80@xmath1 for h - rich wn stars.   theoretical and observational evidence that wr winds depend on metallicity is presented, with implications for evolutionary models, ionizing fluxes, and the role of wr stars within the context of core - collapse supernovae and long - duration gamma ray bursts.   epsf.tex psfig.sty    stars : wolf - rayet ; stars : fundamental parameters ; stars : evolution ; stars : abundances
the experimental precision that will be reached at the next generation of colliders makes it indispensable to improve theoretical predictions significantly.   bhabha scattering @xmath0 is one of the prime processes calling for a better theoretical precision, in particular for non - zero electron masses.   we present a first subset of the full two - loop calculation, namely the factorizable subset.   our calculation is based on diana @xcite.   we reduce tensor integrals to scalar integrals in shifted ( increased ) dimensions and additional powers of various propagators, so - called dots - on - lines.   recurrence relations @xcite remove those dots - on - lines as well as genuine dots - on - lines ( originating from mass renormalization ) and reduce the dimension of the integrals to the generic @xmath1 dimensions.   the resulting master integrals have to be expanded to @xmath2 to ensure proper treatment of all finite terms.   ps.   p/    -1 cm    bi - tp 2002/27 + cern 2002 - 306 + desy 02 - 196 + hep - ph/0211167
we investigate the role of the boundary in the symmetric simple exclusion process with competing nonlocal and local hopping events. with open boundaries,   the system undergoes a first order phase transition from a finite density phase to an empty road phase as the nonlocal hopping rate increases. using a cluster stability analysis  , we determine the location of such an abrupt nonequilibrium phase transition, which agrees well with numerical results.   our cluster analysis provides a physical insight into the mechanism behind this transition.   we also explain why the transition becomes discontinuous in contrast to the case with periodic boundary conditions, in which the continuous phase transition has been observed.
we explore the use of the resource of intra - particle entanglement for secure quantum key distribution in the device - independent scenario. by virtue of the local nature of such entanglement,   bell tests must be implemented locally, which leads to a natural decoupling of device errors from channel errors.   we consider a side - channel attack on the sender s state preparation device, for which the intra - particle entanglement - based scheme is shown to be more secure than the one that uses separable states. of practical relevance   is the fact that such entanglement can be easily generated using linear optics.
we present new spectroscopic observations of the gravitational arcs and the brightest cluster galaxy ( bcg ) in the cluster ms2137 - 23 ( @xmath0 ) obtained with the echelle spectrograph and imager on the keck ii telescope.   we find that the tangential and radial arcs arise from sources at almost identical redshifts ( @xmath1 ).   we combine the measured stellar velocity dispersion profile of the bcg with a lensing analysis to constrain the distribution of dark and stellar matter in the central 100 kpc of the cluster.   our data indicate a remarkably flat inner slope for the dark matter profile, @xmath2, with @xmath3 at 99% cl.   steep inner slopes obtained in cold dark matter cosmological simulations  such as navarro frenk & white ( @xmath4 ) or moore ( 1.5 ) universal dark matter profiles  are ruled out at better than @xmath5%cl.   as baryon collapse is likely to have steepened the dark matter profile from its original form, our data provides a powerful test of the cold dark matter paradigm at the cluster mass scale.
we consider the formation of chiral density waves in quarkyonic matter, which is a phase where cold, dense quarks experience confining forces. we model confinement following gribov and zwanziger, taking the gluon propagator, in coulomb gauge and momentum space, as @xmath0.   we assume that the number of colors, @xmath1, is large, and that the quark chemical potential, @xmath2, is much larger than renormalization mass scale, @xmath3. to leading order in @xmath4 and @xmath5,   a gauge theory with @xmath6 flavors of massless quarks in @xmath7 dimensions naturally reduces to a gauge theory in @xmath8 dimensions, with an enlarged flavor symmetry of @xmath9. through an anomalous chiral rotation, in two dimensions a fermi sea of massless quarks maps directly onto the corresponding theory in vacuum. a chiral condensate forms locally, and varies with the spatial position, @xmath10, as @xmath11. following schn and thies, we term this two dimensional pion condensate a ( quarkyonic ) chiral spiral.   massive quarks also exhibit chiral spirals, with the magnitude of the oscillations decreasing smoothly with increasing mass.   the power law correlations of the wess - zumino - novikov - witten model in @xmath8 dimensions then generate strong infrared effects in @xmath7 dimensions.   = 1    rbrc 823, bnl-90871 - 2009-ja, kuns-2246   ,   ,   , and    dense quark matter, chiral symmetry breaking, large @xmath1 expansion
as an unstable light pure leptonic system, positronium is a very specific probe atom to test bound state qed.   in contrast to ordinary qed for free leptons, the bound state qed theory is not so well understood and bound state approaches deserve highly accurate tests.   we present a brief overview of precision studies of positronium paying special attention to uncertainties of theory as well as comparison of theory and experiment.   we also consider in detail advantages and disadvantages of positronium tests compared to other qed experiments.
fragment average isospin distributions are investigated within a microcanonical multifragmentation model in different regions of the phase diagram.   the results indicate that in the liquid phase @xmath0 versus @xmath1 is monotonically increasing, in the phase coexistence region it has a rise and fall shape and in the gas phase it is constant.   deviations from this behavior may manifest at low fragment multiplicity as a consequence of mass / charge conservation.   characterization of the `` free '' and `` bound '' phases function of fragment charge reconfirms the neutron enrichment of the `` free '' phase with respect to the `` bound '' one irrespectively the localization of the multifragmentation event in the phase diagram.
we outline an interferometric scheme for the detection of bi - mode and multi - mode spatial entanglement of finite - temperature, interacting bose gases. whether entanglement is present in the gas depends on the existence of the single - particle reduced density matrix between different regions of space.   we apply the scheme to the problem of a harmonically trapped repulsive boson pair and show that while entanglement is rapidly decreasing with temperature, a significant amount remains for all interaction strengths at zero temperature.   thus, by tuning the interaction parameter, the distribution of entanglement between many spatial modes can be modified.
electron transport in electric - field - driven tight - binding lattice coupled to fermion baths is comprehensively studied.   we reformulate the problem by using the scattering state method within the coulomb gauge.   calculations show that the formulation justifies direct access to the steady - state bypassing the time - transient calculations, which then makes the steady - state methods developed for quantum dot theories applicable to lattice models.   we show that the effective temperature of the hot - electron induced by a dc electric field behaves as @xmath0 with a numerical constant @xmath1, tight - binding parameter @xmath2, the bloch oscillation frequency @xmath3 and the damping parameter @xmath4. in the small damping limit @xmath5  , the steady - state has a singular property with the electron becoming extremely hot in an analogy to the short - circuit effect.   this leads to the conclusion that the dissipation mechanism can not be considered as an implicit process, as treated in equilibrium theories.   finally, using the energy flux relation, we derive a steady - state current for interacting models where only on - site green s functions are necessary.
optical reference geometry and related concept of inertial forces are investigated in kerr - de sitter spacetimes.   properties of the inertial forces are summarized and their typical behaviour is illustrated.   the intuitive newtonian application of the forces in the relativistic dynamics is demonstrated in the case of the test particle circular motion, static equilibrium positions and perfect fluid toroidal configurations.   features of the optical geometry are illustrated by the embedding diagrams of its equatorial plane.   the embedding diagrams do not cover whole the stationary regions of the spacetimes, therefore the limits of embeddability are established.   a shape of the embedding diagrams is related to the behaviour of the centrifugal force and it is characterized by the number of turning points of the diagrams.   discussion of the number of embeddable photon circular orbits is also included and the typical embedding diagrams are constructed.   the kerr - de sitter spacetimes are classified according to the properties of the inertial forces and embedding diagrams.
a comparative first - principles study of possible bismuth - related centers in and crystals is performed and the results of computer modeling are compared with the experimental data of refs.   @xcite.   the calculated spectral properties of the bismuth centers suggest that the ir luminescence observed in @xcite is most likely caused by centers ( @xmath0 ion in thallium site and a negatively charged chlorine vacancy in the nearest anion site ). on the contrary, @xmath0 substitutional ions and @xmath1 dimers are most likely responsible for the ir luminescence observed in @xcite.
we use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets ( egps ), and low - mass stars. the behavior of individual fe-, mg-, and si - bearing gases and condensates is determined as a function of temperature, pressure, and metallicity.   our results are thus independent of any particular model atmosphere.   the condensation of fe metal strongly affects iron chemistry by efficiently removing fe - bearing species from the gas phase.   monatomic fe is the most abundant fe - bearing gas throughout the atmospheres of egps and l dwarfs and in the deep atmospheres of giant planets and t dwarfs. mg- and   si - bearing gases are effectively removed from the atmosphere by forsterite ( mg@xmath0sio@xmath1 ) and enstatite ( mgsio@xmath2 ) cloud formation.   monatomic mg is the dominant magnesium gas throughout the atmospheres of egps and l dwarfs and in the deep atmospheres of giant planets and t dwarfs.   silicon monoxide ( sio ) is the most abundant si - bearing gas in the deep atmospheres of brown dwarfs and egps, whereas sih@xmath1 is dominant in the deep atmosphere of jupiter and other gas giant planets.   several other fe-, mg-, and si - bearing gases become increasingly important with decreasing effective temperature. in principle, a number of fe, mg, and si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres.
the formation of regular precipitate stripes in the wake of moving chemical reaction - diffusion fronts is investigated.   experiments on the @xmath0 reaction in pva hydrogel yield stripes parallel or slightly oblique to the front that supplies the precursor of the precipitate.   the pattern formation was modeled by phase separation described by the cahn - hilliard equation.   computer simulations reproduced the parallel and the oblique striping as well.   stripes perpendicular to the front are unstable and can not be observed, in complete agreement with the experiments.   pattern formation in the wake of quenching fronts has also been investigated computationally, and compared to the previous results.   it has been shown that below a certain front speed stripes perpendicular to the front will appear. moreover  , they will bend so that their growing end to be kept perpendicular even if the front changes its direction.   this result can be important in designing several nanotechnological and lithographical processes.
we use a time - dependent dynamical mean - field - hydrodynamic model to study mixing - demixing in a degenerate fermion - fermion mixture ( dffm ).   it is demonstrated that with the increase of interspecies repulsion and/or trapping frequencies, a mixed state of dffm could turn into a fully demixed state in both three - dimensional spherically - symmetric as well as quasi - one - dimensional configurations.   such a demixed state of a dffm could be experimentally realized by varying an external magnetic field near a fermion - fermion feshbach resonance, which will result in an increase of interspecies fermion - fermion repulsion, and/or by increasing the external trap frequencies.   pacs numbers : 03.75.ss    instituto de fsica terica, unesp @xmath0 so paulo state university, 01.405 - 900 so paulo, so paulo, brazil
icecube, a future km@xmath0 antarctic ice cherenkov neutrino telescope, is highly sensitive to a galactic supernova ( sn ) neutrino burst.   the cherenkov light corresponding to the total energy deposited by the sn neutrinos in the ice can be measured relative to background fluctuations with a statistical precision much better than 1%.   if the sn is viewed through the earth, the matter effect on neutrino oscillations can change the signal by more than 5%, depending on the flavor - dependent source spectra and the neutrino mixing parameters.   therefore, icecube together with another high - statistics experiment like hyper - kamiokande can detect the earth effect, an observation that would identify specific neutrino mixing scenarios that are difficult to pin down with long - baseline experiments.   in particular, the normal mass hierarchy can be clearly detected if the third mixing angle is not too small, @xmath1.   the small flavor - dependent differences of the sn neutrino fluxes and spectra that are found in state - of - the - art simulations suffice for this purpose.   although the absolute calibration uncertainty at icecube may exceed 5%, the earth effect would typically vary by a large amount over the duration of the sn signal, obviating the need for a precise calibration.   therefore, icecube with its unique geographic location and expected longevity can play a decisive role as a `` co - detector '' to measure sn neutrino oscillations.   it is also a powerful stand - alone sn detector that can verify the delayed - explosion scenario.
the absolute magnitude and perihelion distributions of long - period comets are derived, using data from the lincoln near - earth asteroid research ( linear ) survey.   the results are surprising in three ways.   firstly, the flux of comets through the inner solar system is much lower than some previous estimates.   secondly, the expected rise in comet numbers to larger perihelia is not seen.   thirdly, the number of comets per unit absolute magnitude does not significantly rise to fainter magnitudes.   these results imply that the oort cloud contains many fewer comets than some previous estimates, that small long - period comets collide with the earth too infrequently to be a plausible source of tunguska - style impacts, and that some physical process must have prevented small icy planetesmals from reaching the oort cloud, or have rendered them unobservable. a tight limit   is placed on the space density of interstellar comets, but the predicted space density is lower still  . the number of long - period comets that will be discovered by telescopes such as skymapper, pan - starrs and lsst is predicted, and the optimum observing strategy discussed.
in graph modification problems, one is given a graph  @xmath0 and the goal is to apply a minimum number of modification operations ( such as edge deletions ) to  @xmath0 such that the resulting graph fulfills a certain property.   for example, the cluster deletion problem asks to delete as few edges as possible such that the resulting graph is a disjoint union of cliques.   graph modification problems appear in numerous applications, including the analysis of biological and social networks.   typically, graph modification problems are np - hard, making them natural candidates for parameterized complexity studies.   we discuss several fruitful interactions between the development of fixed - parameter algorithms and the design of heuristics for graph modification problems, featuring quite different aspects of mutual benefits.
we investigate the neutral pion photoproduction on the proton near threshold in covariant chiral perturbation theory with the explicit inclusion of @xmath0 degrees of freedom.   this channel is specially sensitive to chiral dynamics and the advent of very precise data from the mainz microtron has shown the limits of the convergence of the chiral series for both the heavy baryon and the covariant approaches.   we show that the inclusion of the @xmath0 resonance substantially improves the convergence leading to a good agreement with data for a wider range of energies.   = 1
we consider collisions of particles advected in a fluid. as already pointed out by smoluchowski [ _ z.   f. physik.   chemie _, * xcii *, 129 - 168, ( 1917 ) ], macroscopic motion of the fluid can significantly enhance the frequency of collisions between the suspended particles.   this effect was invoked by saffman and turner [ _ j.   fluid mech.   _, * 1 *, 16 - 30, ( 1956 ) ] to estimate collision rates of small water droplets in turbulent rain clouds, the macroscopic motion being caused by turbulence. here   we show that the saffman - turner theory is unsatisfactory because it describes an initial transient only.   the reason for this failure is that the local flow in the vicinity of a particle is treated as if it were a steady hyperbolic flow, whereas in reality it must fluctuate.   we derive exact expressions for the steady - state collision rate for particles suspended in rapidly fluctuating random flows and compute how this steady state is approached. for incompressible flows, the saffman - turner expression is an upper bound.
the ground - state properties of zr and sn isotopes are studied within the relativistic mean field theory.   zr and sn isotopes have received tremendous attention due to various reasons, including the predicted giant halos in the neutron - rich zr isotopes, the unique feature of being robustly spherical in the region of @xmath0sn @xmath1 @xmath2sn and the particular interest of sn isotopes to nuclear astrophysics.   furthermore, four ( semi- ) magic neutron numbers, 40, 50, 82 and 126, make these two isotopic chains particularly important to test the pairing correlations and the deformations in a microscopic model. in the present work,   we carry out a systematic study of zr and sn isotopes from the proton drip line to the neutron drip line with deformation effects, pairing correlations and blocking effects for nuclei with odd number of neutrons properly treated. a constrained calculation with quadrupole deformations   is performed to find the absolute minimum for each nucleus on the deformation surface.   all ground - state properties, including the separation energies, the odd - even staggerings, the nuclear radii, the deformations and the single - particle spectra are analyzed and discussed in detail.
intrinsic absorbers are significant components of agn environments that provide valuable information and interesting challenges  . we present a very brief ( and biased, and sometimes speculative ) overview of intrinsic absorbers from the perspective of different absorption line classes.   we also discuss ways of addressing and learning from the  problem " of partial coverage of the background light source, with some examples based on new high - resolution rest - frame uv spectra of quasars.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study adiabatic pumping through a two - level quantum dot with spin - orbit coupling. using a diagrammatic real - time approach,   we calculate both the pumped charge and spin for a periodic variation of the dot s energy levels in the limit of weak tunnel coupling.   thereby, we compare the two limits of vanishing and infinitely large charging energy on the quantum dot.   we discuss the dependence of the pumped charge and pumped spin on gate voltages, the symmetry in the tunnel - matrix elements and spin - orbit coupling strength.   we identify the possibility to generate pure spin currents in the absence of charge currents.
we study theoretically the spatiotemporal response of a lipid membrane submitted to a local chemical change of its environment, taking into account the time - dependent profile of the reagent concentration due to diffusion in the solution above the membrane.   we show that the effect of the evolution of the reagent concentration profile becomes negligible after some time.   it then becomes possible to extract interesting properties of the membrane response to the chemical modification.   we find that a local density asymmetry between the two monolayers relaxes by spreading diffusively in the whole membrane.   this behavior is driven by intermonolayer friction.   moreover, we show how the ratio of the spontaneous curvature change to the equilibrium density change induced by the chemical modification can be extracted from the dynamics of the local membrane deformation.   such information can not be obtained by analyzing the equilibrium vesicle shapes that exist in different membrane environments in light of the area - difference elasticity model.   membrane dynamics, local perturbation, chemical modification, area - difference elasticity, intermonolayer friction
we analyze the self - averaging properties of time - reversed solutions of the paraxial wave equation with random coefficients, which we take to be markovian in the direction of propagation.   this allows us to construct an approximate martingale for the phase space wigner transform of two wave fields. using a priori @xmath0-bounds available in the time - reversal setting  , we prove that the wigner transform in the high frequency limit converges in probability to its deterministic limit, which is the solution of a transport equation.
we propose a new scheme for numerically computing collective - mode spectra for large - size systems, using a reformulation of the random phase approximation. in this study  , we apply this method to investigate the spectrum and nature of the spin - waves of a ( iii, mn)v diluted magnetic semiconductor.   we use an impurity band picture to describe the interaction of the charge carriers with the local mn spins.   the spin - wave spectrum is shown to depend sensitively on the positional disorder of the mn atoms inside the host semiconductor. both localized and extended spin - wave modes are found.   unusual spin and charge transport is implied.   3.25 true in
for a gas trapped in a harmonic potential, the sloshing ( or kohn ) mode is undamped and its frequency coincides with the trap frequency, independently of the statistics, interaction and temperature of the gas.   however, experimental trap potentials have usually gaussian shape and anharmonicity effects appear as the temperature and, in the case of fermions, the filling of the trap are increased.   we study the sloshing mode of a degenerate fermi gas in an anharmonic trap within the boltzmann equation, including in - medium effects in both the transport and collision terms.   the calculated frequency shifts and damping rates of the sloshing mode due to the trap anharmonicity are in satisfactory agreement with the available experimental data.   we also discuss higher - order dipole, octupole, and bending modes and show that the damping of the sloshing mode is caused by its coupling to these modes.
the exact superposition of a central static black hole with surrounding thin disk in presence of a magnetic field is investigated.   we consider two models of disk, one of infinite extension based on a kuzmin - chazy - curzon metric and other finite based on the first morgan - morgan disk.   we also analyze a simple model of active galactic nuclei consisting of black hole, a kuzmin - chazy - curzon disk and two rods representing jets, in presence of magnetic field.   to explain the stability of the disks we consider the matter of the disk made of two pressureless streams of counterrotating charged particles ( counterrotating model ) moving along electrogeodesic.   using the rayleigh criterion we derivate for circular orbits the stability conditions of the particles of the streams.   the influence of the magnetic field on the matter properties of the disk and on its stability are also analyzed.
we study critical casimir forces between planar walls and geometrically structured substrates within mean - field theory. as substrate structures, crenellated surfaces consisting of periodic arrays of rectangular crenels and merlons   are considered. within the widely used proximity force approximation,   both the top surfaces of the merlons and the bottom surfaces of the crenels contribute to the critical casimir force.   however, for such systems the full, numerically determined critical casimir forces deviate significantly from the pairwise addition formalism underlying the proximity force approximation.   a first - order correction to the proximity force approximation is presented in terms of a step contribution arising from the critical casimir interaction between a planar substrate and the right - angled steps of the merlons consisting of their upper and lower edges as well as their sidewalls.
classical models for competition between two species usually predict exclusion or divergent evolution of resource exploitation.   however, recent experimental data show that coexistence is possible for very similar species competing for the same resources _ without _ niche partition.   motivated by this experimental challenge to classical competition theory, we propose an individual - based stochastic competition model, which is essentially a modification of a deterministic lotka - volterra type model.   the proposed model of competition dynamics incorporates the effects of a discrete genotype, which determines the individual s adaptation to the environment, as well as its interaction with the other species.   + _ keywords : _ population dynamics ; lotka - volterra model : competition ; individual - based model.
helium abundances and atmospheric parameters have been determined from high resolution spectra for a new sample of 46 bright hot subdwarf b ( sdb ) stars.   the helium abundances have been measured with high accuracy.   we confirm the correlation of helium abundance with temperature and the existence of two distinct sequences in helium abundance found previously.   we focused on isotopic shifts of helium lines and found @xmath0he to be strongly enriched in 8 of our programme stars.   most of these stars cluster in a small temperature range between @xmath1 and @xmath2 very similar to the known @xmath0he - rich main sequence b stars, which cluster at somewhat lower temperatures.   this phenomenon is most probably related to diffusion processes in the atmosphere, but poses a challenge to diffusion models.
we have carried out extensive simulations of the angle - resolved photoemission ( arpes ) intensity in bi2212 within the one - step and three - step type models using a first - principles band theory framework.   the focus is on understanding the behavior of emissions from the antibonding and bonding bands arising from the @xmath0 bilayers around the @xmath1 symmetry point.   the specific issues addressed include : dependencies of the photointensity on the energy and polarization of the incident light ; character of the initial and final states involved as well as the spectrum of the relevant final states ; and, changes in the spectral intensity as a function of the perpendicular component, @xmath2, of the momentum of the photoelectron.   considerable insight into the nature of individual transitions is adduced by examining the momentum matrix element for bulk transitions within the solid and by further decomposing this matrix element into contributions from various atomic sites and angular momentum channels.   these results indicate that, via remarkable interference effects, the arpes matrix element can in particular cases help zoom in on the properties of electrons excited from specific sites and/or angular momentum channels even in a complex material.
whether or not space - time is fundamentally discrete is of central importance for the development of the theory of quantum gravity.   if the fundamental description of space - time is discrete, typically represented in terms of a graph or network, then the apparent smoothness of geometry on large scales should be imperfect   it should have defects. here, we review a model for space - time defects and summarize the constraints on the prevalence of these defects that can be derived from observation.
classical configurations in the @xmath0 model on @xmath1 is studied with twisted boundary conditions. starting from fractional instantons with the @xmath2 twisted boundary conditions, we review briefly the relevance of our study to resurgence phenomenon in field theory.   we consider primarily configurations composed of multiple fractional instantons, called  neutral bions ", which are identified as  perturbative infrared renormalons ".   we construct an explicit ansatz corresponding to topologically trivial configurations containing one fractional instanton ( @xmath3 ) and one fractional anti - instanton ( @xmath4 ), which is guaranteed to become a solution of field equations asymptotically for large separations.   the attractive interactions between the instanton constituents from small to large separations are found to be consistent with the standard separated - instanton calculus.   our results suggest that the ansatz enables us to study bions and the related physics for a wide range of separations.   this talk is mainly based on our recent work published in jhep * 1406 *, 164 ( 2014 )  ].
we revisit the filamentary structures of galaxies around the virgo cluster, exploiting a larger dataset based on the hyperleda database than previous studies.   in particular, this includes a large number of low - luminosity galaxies, resulting in better sampled individual structures.   we confirm seven known structures in the distance range 4  @xmath0  mpc  @xmath1 sgy  @xmath1 16  @xmath0  mpc, now identified as filaments, where sgy is the axis of the supergalactic coordinate system roughly along the line of sight.   the hubble diagram of the filament galaxies suggests they are infalling toward the main - body of the virgo cluster.   we propose that the collinear distribution of giant elliptical galaxies along the fundamental axis of the virgo cluster is smoothly connected to two of these filaments ( leo  ii  a and b ). behind the virgo cluster ( 16  @xmath0  mpc  @xmath1 sgy  @xmath1 27  @xmath0  mpc )  , we also identify a new filament elongated toward the ngc  5353/4 group ( `` ngc  5353/4 filament '' ) and confirm a sheet that includes galaxies from the w and m clouds of the virgo cluster ( `` w - m sheet '' ). in the hubble diagram, the ngc  5353/4 filament galaxies show infall toward the ngc 5353/4 group, whereas the w - m sheet galaxies do not show hints of gravitational influence from the virgo cluster. the filamentary structures identified can now be used to better understand the generic role of filaments in the build - up of galaxy clusters at z  @xmath2  0.
we present a new method for the numerical evaluation of arbitrary loop integrals in dimensional regularization.   we first derive mellin - barnes integral representations and apply an algorithmic technique, based on the cauchy theorem, to extract the divergent parts in the @xmath0 limit.   we then perform an @xmath1-expansion and evaluate the integral coefficients of the expansion numerically.   the method yields stable results in physical kinematic regions avoiding intricate analytic continuations.   it can also be applied to evaluate both scalar and tensor integrals without employing reduction methods.   we demonstrate our method with specific examples of infrared divergent integrals with many kinematic scales, such as two - loop and three - loop box integrals and tensor integrals of rank six for the one - loop hexagon topology.
tunable imaging filters have been used for a variety of science programmes on the anglo - australian and william herschel telescopes during the last five years.   this contribution describes these novel devices and reviews the science ( both galactic and extragalactic ) done with them.   possible strategies for implementing a tunable filter at the vlt are also discussed.   significant scientific potential exists for a tunable filter on the vlt, particularly in the years before such capability becomes available on 8  10  m - class telescopes elsewhere.
we study the gravitational vacuum star ( gravastar ) configuration as proposed by @xcite in a model where the interior de sitter spacetime segment is continuously extended to the exterior schwarzschild spacetime.   the multilayered structure of @xcite - @xcite is replaced by a continuous stress - energy tensor at the price of introducing anisotropy in the ( fluid ) model of the gravastar. either with an ansatz for the equation of state connecting the radial @xmath0 and tangential @xmath1 pressure or with a calculated equation of state with non - homogeneous energy / fluid density, solutions are obtained which in all aspects satisfy the conditions expected for an anisotropic gravastar @xcite.   certain energy conditions have been shown to be obeyed and a polytropic equation of state has been derived.   stability of the solution with respect to possible axial perturbation is shown to hold.   pacs numbers : 04.20.dw, 04.40.dg, 97.60.-s + key words : gravastar, desitter interiors, black hole alternatives +
we present a period - luminosity - amplitude analysis of 5899 red giant and binary stars in the large magellanic cloud, using publicly available observations of the macho project. for each star  , we determined new periods, which were double - checked in order to exclude aliases and false periods.   the period - luminosity relations confirm the existence of a short - period, small - amplitude p   l sequence at periods shortward of seq.   a. we point out that the widely accepted sequence of eclipsing binaries between seqs.   c and d, known as seq.   e, does not exist.   the correct position for seq.   e is at periods a factor of two greater, and the few stars genuinely lying between seq.   c and d are under - luminous mira variables, presumably enshrouded in dust.   the true seq.   e overlaps with the sequence of long secondary periods ( seq.   d ) and their p   l relation is well described by a simple model assuming roche geometry.   the amplitudes of lsps have properties that are different from both the pulsations and the ellipsoidal variations, but they are more similar to the former than the latter, arguing for pulsation rather than binarity as the origin of the lsp phenomenon.
we consider the environment - affected dynamics of @xmath0 self - interacting particles living in one - dimensional double wells.   two topics are dealt with.   first, we consider the production of entangled states of two - level systems. we show that by adiabatically varying the well biases we may dynamically generate maximally entangled states, starting from initially unentangled product states  . entanglement degradation due to a common type of environmental influence is then computed by solving a master equation.   however, we also demonstrate that entanglement production is unaffected if the system - environment coupling is of the type that induces `` motional narrowing ''. as our second but related topic,   we construct a different master equation that seamlessly merges error protection / detection dynamics for quantum information with the environmental couplings responsible for producing the errors in the first place.   adiabatic avoided crossing schemes are used in both topics.
we apply qcd finite energy sum rules to the scalar - isoscalar current to determine the lightest @xmath0 meson in this channel.   we use ` pinch - weights'to improve the reliability of the qcd predictions and reduce the sensitivity to the cut - off @xmath1. a decaying exponential   is included in the weight function to allow us to focus on the contribution from low mass states to the phenomenological integral.   on the theoretical side we include ope contributions up to dimension six and a contribution due to instantons taken from the instanton liquid model.   phenomenologically, we incorporate experimental data by using a coupling scheme for the scalar current which links the vacuum polarisation to the @xmath2 scattering amplitude via the scalar form factor.   we find that the sum rules are well saturated for certain instanton parameters.   we conclude that the @xmath3 definitely contains a large @xmath0 component, whereas the @xmath4 most likely does not.   we are able to estimate the average light quark mass and find @xmath5 mev.   qcd finite energy sum rules + and the isoscalar scalar mesons + s.  n.  cherry@xmath6 and m.  r.  pennington@xmath7 + @xmath6 _ groupe de physique thorique, ipn + universit de paris - sud, + f-91406 orsay cdex, france. _   + @xmath7 _ institute for particle physics phenomenology, + university of durham, + durham, dh1 3le, u.k. _    = 6.0 mm = 1.5 mm
it has long been proposed that low frequency qpos in stellar mass black holes or their equivalents in super massive black holes are results of resonances between infall and cooling time scales.   we explicitly compute these two time scales in a generic situation to show that resonances are easily achieved. during an outburst of a transient black hole candidate ( bhc ), the accretion rate of the keplerian disk as well as the geometry of the comptonizing cloud change very rapidly. during some period,   resonance condition between the cooling time scale ( predominantly by comptonization ) and the infall time scale of the comptonizing cloud is roughly satisfied.   this leads to low frequency quasi - periodic oscillations ( lfqpos ) of the compton cloud and the consequent oscillation of hard x - rays. in this paper  , we explicitly follow the bhc h  1743 - 322 during its 2010 outburst.   we compute compton cooling time and infall time on several days and show that qpos take place when these two roughly agree within @xmath0%, i.e., the resonance condition is generally satisfied.   we also confirm that for the sharper lfqpos ( i.e., higher q - factors ) the ratio of two time scales is very close to 1.   x - rays : binaries  stars : individual : h  7143 - 322  black holes  shock waves  accretion   accretion disks  radiation : dynamics
we investigate energy transport in several two - level atom or spin-1/2 models by a direct coupling to heat baths of different temperatures.   the analysis is carried out on the basis of a recently derived quantum master equation which describes the nonequilibrium properties of internally weakly coupled systems appropriately.   for the computation of the stationary state of the dynamical equations, we employ a monte carlo wave - function approach.   the analysis directly indicates normal diffusive or ballistic transport in finite models and hints toward an extrapolation of the transport behavior of infinite models.
it has been proposed that primordial gas in early dark matter halos, with virial temperatures @xmath0k, can avoid fragmentation and undergo rapid collapse, possibly resulting in a supermassive black hole ( smbh ).   this requires the gas to avoid cooling and to remain at temperatures near @xmath1 k. we show that this condition can be satisfied in the presence of a sufficiently strong primordial magnetic field, which heats the collapsing gas via ambipolar diffusion. if the field has a strength above @xmath2 ( comoving ) ng, the collapsing gas is kept warm ( @xmath1 k ) until it reaches the critical density @xmath3 at which the roto  vibrational states of @xmath4 approach local thermodynamic equilibrium.   @xmath4cooling then remains inefficient, and the gas temperature stays near @xmath5k, even as it continues to collapse to higher densities.   the critical magnetic field strength required to permanently suppress @xmath4cooling is somewhat higher than upper limit of @xmath6ng from the cosmic microwave background ( cmb ).   however, it can be realized in the rare @xmath7 regions of the spatially fluctuating @xmath8field ; these regions contain a sufficient number of halos to account for the @xmath9 quasar bhs.
the hierarchical reference theory ( hrt ) of fluids is a general framework for the description of phase transitions in microscopic models of classical and quantum statistical physics.   the foundations of hrt are briefly reviewed in a self - consistent formulation which includes both the original sharp cut - off procedure and the smooth cut - off implementation, which has been recently investigated.   the critical properties of hrt are summarized, together with the behavior of the theory at first order phase transitions  . however, the emphasis of this presentation is on the close relationship between hrt and non perturbative renormalization group methods, as well as on recent generalizations of hrt to microscopic models of interest in soft matter and quantum many body physics.
we introduce in this paper a new four - parameter generalized version of the linear failure rate ( lfr ) distribution which is called beta - linear failure rate ( blfr ) distribution.   the new distribution is quite flexible and can be used effectively in modeling survival data and reliability problems.   it can have a constant, decreasing, increasing, upside - down bathtub ( unimodal ) and bathtub - shaped failure rate function depending on its parameters.   it includes some well - known lifetime distributions as special sub - models.   we provide a comprehensive account of the mathematical properties of the new distributions. in particular, a closed - form expressions for the density, cumulative distribution and hazard rate function of the blfr is given.   also, the @xmath0th order moment of this distribution is derived.   we discuss maximum likelihood estimation of the unknown parameters of the new model for complete sample and obtain an expression for fishers information matrix. in the end, to show the flexibility of this distribution and illustrative purposes, an application using a real data set is presented.   msc : 60e05 ; 62f10 ; 62p99.   keywords : beta distribution ; hazard function ; linear failure rate distribution ; maximum likelihood estimation ; moments ; simulation.
old and new puzzles of cosmology are reexamined from the point of view of quantum theory of the universe developed here.   it is shown that in proposed approach the difficulties of the standard cosmology do not arise.   the theory predicts the observed dimensions of the nonhomogeneities of matter density and the amplitude of the fluctuations of the cosmic background radiation temperature in the universe and points to a new quantum mechanism of their origin.   it allows to obtain the value of the deceleration parameter which is in good agreement with the recent sne ia measurements.   the theory explains the large value of entropy of the universe and describes other parameters.   * properties of the quasistationary universe in context of the big - bang cosmology problems *    v.e.   kuzmichev and v.v.   kuzmichev + bogolyubov institute for theoretical physics, national academy of sciences of ukraine, kiev, 03143 ukraine
we have analyzed high velocity resolution hi synthesis observations of the nearly face  on sc galaxy ngc 1232.   the neutral gas distribution extends well beyond the optical extent of the galaxy.   as expected, local peaks in the hi column density are associated with the spiral arms.   further, the hi column density drops precipitously near the center of the galaxy.   closed contours in the velocity field suggest either that the system is warped, or that the rotation curve declines.   the velocity dispersion is approximately constant throughout the system, with a median value of 9.9 @xmath0 1.8. when corrected for rotational broadening,   there is no indication of a radial trend in the neutral gas velocity dispersion in this galaxy.   3.4truein to appear in _ the astronomical journal _    0.5truein
this paper studies secrecy transmission with the aid of a group of wireless energy harvesting ( weh)-enabled amplify - and - forward ( af ) relays performing cooperative jamming ( cj ) and relaying.   the source node in the network does _ simultaneous wireless information and power transfer ( swipt ) _ with each relay employing a power splitting ( ps ) receiver in the first phase ; each relay further divides its harvested power for forwarding the received signal and generating artificial noise ( an ) for jamming the eavesdroppers in the second transmission phase. in the centralized case with global channel state information ( csi ), we provide closed - form expressions for the optimal and/or suboptimal af - relay beamforming vectors to maximize the achievable secrecy rate subject to individual power constraints of the relays, using the technique of semidefinite relaxation ( sdr ), which is proved to be tight. a fully _ distributed _ algorithm utilizing only local csi at each relay is also proposed as a performance benchmark.   simulation results validate the effectiveness of the proposed multi - af relaying with cj over other suboptimal designs.    artificial noise, cooperative jamming, amplify - and - forward relaying, secrecy communication, semidefinite relaxation, wireless energy harvesting  .           
a radio tomographic imaging ( rti ) system uses the received signal strength ( rss ) measured by rf sensors in a static wireless network to localize people in the deployment area, without having them to carry or wear an electronic device.   this paper addresses the fact that small - scale changes in the position and orientation of the antenna of each rf sensor can dramatically affect imaging and localization performance of an rti system.   however, the best placement for a sensor is unknown at the time of deployment.   improving performance in a deployed rti system requires the deployer to iteratively `` guess - and - retest '', _ i.e. _, pick a sensor to move and then re - run a calibration experiment to determine if the localization performance had improved or degraded.   we present an rti system of _ servo - nodes _, rf sensors equipped with servo motors which autonomously `` dial it in '', _   i.e. _, change position and orientation to optimize the rss on links of the network. by doing so,   the localization accuracy of the rti system is quickly improved, without requiring any calibration experiment from the deployer.   experiments conducted in three indoor environments demonstrate that the servo - nodes system reduces localization error on average by 32% compared to a standard rti system composed of static rf sensors.   radio tomographic imaging, device - free localization, rf sensors, multipath fading
we analyze 205  ks of imaging data of the active binary, capella, obtained with the  high resolution camera imager ( hrc - i ) to determine whether capella shows any variability at timescales @xmath0  ks.   we find that a clear signal for variability is present for timescales @xmath1  ks, and that the light curves show evidence for excess fluctuation over that expected from a purely poisson process.   this overdispersion is consistent with variability at the 2 - 7% level, and suggests that the coronae on the binary components of capella are composed of low - density plasma and low - lying loops.
the detection of bright x - ray flares superimposed on the regular afterglow decay in _ swift _ gamma - ray bursts has triggered theoretical speculations on their origin.   we study the temporal properties of flares due to internal dissipation and external shock mechanisms.   we first show that at least a sizable fraction of the flares can not be related to external shock mechanisms, since external shock flares evolve on much longer time scales than observed.   we then study flares from internal dissipation, showing that the temporal properties allow us to distinguish the emission of slow early shells from that of late faster shells.   we show that, due to the rapid evolution of the detected flares, it is most likely that the flares are produced by relatively fast shells ejected by the central engine shortly before they are observed.   this implies that the central engine must be active for, in some cases, as long as one day.   we finally discuss the constraints and implications that this observation has on the properties and physics of the inner engine, and we elaborate on possible future observational tests on the flare sample to further understand their origin and physics.   gamma - ray : bursts  radiation mechanisms : non - thermal
the main theoretical tool to provide precise predictions for scattering cross sections of strongly interacting particles is perturbative qcd. starting at next - to - leading order ( nlo )   the calculation suffers from unphysical ir - divergences that cancel in the final result. at nlo there   exist general subtraction algorithms to treat these divergences during a calculation.   since the lhc demands for more precise theoretical predictions, general subtraction methods at next - to - next - to - leading order ( nnlo ) are needed.   + this proceeding outlines the four - dimensional formulation of the sector improved residue subtraction.   the subtraction scheme stripper and in particular its extension to arbitrary multiplicities is explained.   therefore, it furnishes a general framework for the calculation of nnlo cross sections in perturbative qcd.
i review existing methods for determining mass - loss rates of red giants and red supergiants based on infrared data.   the simplest method is based on models for the absorption and emission by dust which forms in the dense outflows from these cool stars.   i discuss the parameters and assumptions upon which the method relies, review relationships between the mass - loss rate and infrared colours or far - infrared flux density, and propose a new formula for the mass - loss rate as a function of the visual extinction.   i also briefly discuss the use of atomic and molecular transitions at infrared wavelengths.
the appearance of quark matter in the core of hybrid stars is a fundamental issue in such compact stars.   the central density of these stars is sufficiently high such that nuclear matter undergoes a further change into other exotic phases that consist of hyperons and quarks.   however, the equation of state ( eos ) for the high - density matter is still not clear and several recent observations have indicated the limitations of the eoss ; theoretical studies should try to elucidate the eoss.   it is believed that the inner regions of the stars should consist of a mixed hadron - quark phase.   we study the mixed hadron - quark phase, taking into account finite - size effects, and find that that the mixed phase should be restricted to a narrower region.   therefore, a quark matter phase should appear in the central region.
coherently driven atomic gases inside optical cavities hold great promises in generating rich dynamics and exotic states of matter. recently, it has been shown that a novel topological superradiant state exists in a two - component degenerate fermi gas coupled to a cavity, where local order parameters coexist with global topological invariants. in this work,   we characterise in detail various properties of this exotic state, focusing on the feedback interactions between the atoms and the cavity field. in particular, we demonstrate that the cavity - induced inter - band couplings play a crucial role in inducing the topological phase transition between the conventional and the topological superradiant state.   furthermore, we analyse how the closing and reopening of the atomic bulk gap across the topological phase boundary leaves interesting signatures in the cavity field.   we also discuss the robustness of the topological superradiant state by investigating the steady - state phase diagram under various circumstances.   our work provides many valuable insights into the unique atom - cavity hybrid system under study, and is helpful for future experimental exploration of the topological superradiant state.
in the following we stress the advantages of the nica research programme in the context of studying the spectator - induced electromagnetic phenomena present in proton - nucleus and heavy ion collisions.   we point at the specific interest of using these phenomena as a new, independent source of information on the space - time evolution of the reaction and of the non - perturbative process of particle production.   we propose an extended series of measurements of well - defined observables to be performed in different types of nuclear reactions and in the whole range of collision energies available to nica.   we expect these measurements to bring very valuable new insight into the mechanism of non - perturbative strong interactions, complementary to the studies made at the sps at cern, rhic at bnl, and the lhc.
the binary coding theory and subspace codes for random network coding exhibit similar structures.   the method used to obtain a singleton bound for subspace codes mimic the technique used in obtaining the singleton bound for binary codes.   this motivates the question of whether there is an abstract framework that captures these similarities. as a first step towards answering this question  , we use the lattice framework proposed in @xcite.   a lattice is a partially ordered set in which any two elements have a least upper bound and a greatest lower bound.   a ` lattice scheme'is defined as a subset of a lattice. in this paper  , we derive a singleton bound for lattice schemes and obtain singleton bounds known for binary codes and subspace codes as special cases.   the lattice framework gives additional insights into the behaviour of singleton bound for subspace codes.   we also obtain a _ new _ upper bound on the code size for non - constant dimension codes.   the plots of this bound along with plots of the code sizes of known non - constant dimension codes in the literature reveal that our bound is tight for certain parameters of the code.
tunable oscillatory modes of electric - field domains in doped semiconductor superlattices are reported.   the experimental investigations demonstrate the realization of tunable, ghz frequencies in gaas - alas superlattices covering the temperature region from 5 to 300  k. the orgin of the tunable oscillatory modes is determined using an analytical and a numerical modeling of the dynamics of domain formation.   three different oscillatory modes are found.   their presence depends on the actual shape of the drift velocity curve, the doping density, the boundary condition, and the length of the superlattice. for most bias regions,   the self - sustained oscillations are due to the formation, motion, and recycling of the domain boundary inside the superlattice.   for some biases, the strengths of the low and high field domain change periodically in time with the domain boundary being pinned within a few quantum wells. the dependency of the frequency on the coupling leads to the prediction of a new type of tunable ghz oscillator based on semiconductor superlattices.   +    = 10000
we investigate the fraction of z @xmath0 0.3 lyman alpha emitting galaxies ( laes ) which host active galactic nucleus activity, which is typically from 1  5% at 2 @xmath1 z @xmath1 6. using optical spectroscopy of 23 laes at 0.2 @xmath2 z @xmath2 0.45 selected with galex uv data, we probe for agn with a variety of methods, including line widths, diagnostic line ratios, high - ionization emission, infrared activity and x - ray luminosity.   we found that our sample of low - redshift laes has an agn fraction of 43 @xmath3%, significantly higher than at high redshift.   while previous results have shown that low - redshift laes have a lower space density than their high - redshift analogs, these results show that star - forming laes at low - redshift are rarer still.   accounting for differences in available agn classification methods, we conclude that rest - frame optical spectroscopy is necessary to identify low - luminosity agns in laes at high redshift, and that limits on the x - ray flux are necessary to determine the extent to which the agn contaminates the ly@xmath4  fluxes.
deep architecture such as hierarchical semi - markov models is an important class of models for nested sequential data.   current exact inference schemes either cost cubic time in sequence length, or exponential time in model depth.   these costs are prohibitive for large - scale problems with arbitrary length and depth. in this contribution  , we propose a new approximation technique that may have the potential to achieve sub - cubic time complexity in length and linear time depth, at the cost of some loss of quality.   the idea is based on two well - known methods : gibbs sampling and rao - blackwellisation.   we provide some simulation - based evaluation of the quality of the rgbs with respect to run time and sequence length.
while theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co - located with a flow stagnation point, the introduction of asymmetry typically leads to non - ideal flows across the null point. to understand this behavior, we present exact expressions for the motion of three - dimensional linear null points.   the most general expression shows that linear null points move in the direction along which the vector field and its time derivative are antiparallel.   null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non - ideal flows across topological boundaries.   null point motion is described intrinsically by parameters evaluated locally ; however, global dynamics help set the local conditions at the null point. during a bifurcation of a degenerate null point into a null - null pair or the reverse,   the instantaneous velocity of separation or convergence of the null - null pair will typically be infinite along the null space of the jacobian matrix of the magnetic field, but with finite components in the directions orthogonal to the null space.   not all bifurcating null - null pairs are connected by a separator.   furthermore, except under special circumstances, there will not exist a straight line separator connecting a bifurcating null - null pair.   the motion of separators can not be described using solely local parameters, because the identification of a particular field line as a separator may change as a result of non - ideal behavior elsewhere along the field line.
we present solution of the equations for relativistic static spherically symmetric stars ( ssss ) in the model of minimal dilatonic gravity ( mdg ) using the polytropic equation of state.   a polytropic equation of state, which has a good fitting with a more realistic one, is used.   results are obtained for all variables of a single neutron star in the model of mdg.   the maximum mass about two solar masses is in accordance with the latest observations of pulsars.   several new effects are observed for the variables related with the dilaton @xmath0 and the cosmological constant @xmath1.   the mass - radius relation is also obtained.   special attention is paid to the behavior of the quantities which describe the effects analogous to those of dark energy and dark matter in mdg.   the results of the present paper confirm the conclusion that the dilaton @xmath0 is able to play simultaneously the role of dark energy and dark matter.
the multidimensional gravity on the principal bundle with the su(2 ) gauge group is considered.   the numerical investigation of the spherically symmetric metrics with the center of symmetry is made.   the solution of the gravitational equations depends on the boundary conditions of the `` su(2 ) gauge potential '' ( off - diagonal metric components ) at the symmetry center and on the type of symmetry ( symmetrical or antisymmetrical ) of these potentials. in the chosen range of the boundary conditions   it is shown that there are two types of solutions : wormhole - like and flux tube.   the physical application of such kind of solutions as quantum handles in a spacetime foam is discussed.
using the _ rossixte _ experiment, we detect weak x - ray emission from the recurrent be / x - ray transient a0535 + 26 at a time when the optical counterpart v725 tau displayed h@xmath0 in absorption, indicating the absence of a circumstellar disc.   the x - ray radiation is strongly modulated at the 103.5-s pulse period of the neutron star, confirming that it originates from a0535 + 26.   the source is weaker than in previous quiescence detections by two orders of magnitude and should be in the centrifugal inhibition regime.   we show that the x - ray luminosity can not be due to accretion on to the magnetosphere of the neutron star.   therefore this detection represents a new state of the accreting pulsar.   we speculate that the x - ray emission can be due to some matter leaking through the magnetospheric barrier or thermal radiation from the neutron star surface due to crustal heating.   the observed luminosity is probably compatible with recent predictions of thermal radiation from x - ray transients in quiescence.   the detection of the x - ray source in the inhibition regime implies a reduced density in the outflow from the be companion during its disc - less phase.
we calculate the absorption efficiency of the composite grains, made up of host silicate spheroids and inclusions of ices / graphites / or voids, in the spectral region @xmath0 m the absorption efficiencies of the composite spheroidal grains for three axial ratios are computed using the discrete dipole approximation ( dda ) as well as using the effective medium approximation & t - matrix ( emt - tmatrix ) approach.   we study the absorption as a function of the volume fraction of the inclusions and porosity.   in particular, we study the variation in the @xmath1 m feature with the volume fraction of the inclusions and porosity.   we then calculate the infrared fluxes for these composite grains and compare the model curves with the average observed iras - lrs curve, obtained for several circumstellar dust shells around stars.   these results on the composite grains show that the wavelength of the peak absorption shifts and the width of the @xmath1 m feature varies with the variation in the volume fraction of the inclusions.   the model curves for composite grains with axial ratios not very large ( ar@xmath21.3 ) and volume fractions of inclusions with f=0.20, and dust temperature of about 250 - 300@xmath3k, fit the observed emission curves reasonably well.   
it is not fully understood how electromagnetic waves propagate through plasma fluctuations when the size of the fluctuations is comparable with the wavelength of the incident radiation. in this paper, the perturbing effect of a turbulent plasma density layer on a traversing microwave beam is simulated with full - wave simulations. the deterioration of the microwave beam is calculated as a function of the characteristic turbulence structure size, the turbulence amplitude, the depth of the interaction zone and the size of the waist of the incident beam.   the maximum scattering is observed for a structure size on the order of half the vacuum wavelength.   the scattering and beam broadening was found to increase linearly with the depth of the turbulence layer and quadratically with the fluctuation strength.   consequences for experiments and 3d effects are considered.
an event - driven molecular dynamics simulation of inelastic hard spheres contained in a cylinder and subject to strong vibration reproduces accurately experimental results@xcite for a system of vibrofluidized glass beads.   in particular, we are able to obtain the velocity field and the density and temperature profiles observed experimentally. in addition  , we show that the appearance of convection rolls is strongly influenced by the value of the sidewall - particle restitution coefficient.   suggestions for observing more complex convection patterns are proposed.
our knowledge of the initial conditions and early stages of high mass star formation is very limited. we will review recent surveys of regions in the early stages of massive star formation using molecular tracers of high density and dust continuum emission and consider the status of evolutionary schemes.   comparison to the situation for low mass, relatively isolated star formation will be used to illustrate the outstanding issues in massive star formation.   the problem of initial conditions is particularly acute because there is a lack of observational evidence for regions capable of forming massive stars _ before _   star formation actually begins. by analogy with the pre - protostellar cores ( ppcs )   studied for low - mass star formation, one might call such regions pre - proto - cluster cores ( ppclcs )  . we will conclude with some speculation about what such cores might look like and possibilities for their detection.
we investigate the influence of spatial dispersion on atom - surface quantum friction.   we show that for atom - surface separations shorter than the carrier s mean free path within the material, the frictional force can be several orders of magnitude larger than that predicted by local optics.   in addition, when taking into account spatial dispersion effects, we show that the commonly used local thermal equilibrium approximation underestimates by approximately 95% the drag force, obtained by employing the recently reported nonequilibrium fluctuation - dissipation relation for quantum friction. unlike the treatment based on local optics, spatial dispersion in conjunction with corrections to local thermal equilibrium not only change the magnitude but also the distance scaling of quantum friction.
we present  radially - resolved - equilibrium - models " for the growth of stellar and gaseous disks in cosmologically accreting massive halos.   our focus is on objects that evolve to redshifts @xmath0.   we solve the time - dependent equations that govern the radially dependent star - formation rates, inflows and outflows from and to the inter- and circum - galactic medium, and inward radial gas flows within the disks.   the stellar and gaseous disks reach equilibrium configurations on dynamical time scales much shorter than variations in the cosmological dark matter halo growth and baryonic accretions rates.   we show analytically that mass and global angular momentum conservation naturally give rise to exponential gas and stellar disks over many radial length scales.   as expected, the gaseous disks are more extended as set by the condition toomre @xmath1 for star - formation.   the disks rapidly become baryon dominated. for massive, @xmath2 halos at redshift @xmath3, we reproduced the typical observed star - formation rates of @xmath4, stellar masses @xmath5, gas contents @xmath6, half mass sizes of 4.5 and 5.8 kpc for the stars and gas, and characteristic surface densities of @xmath7 and @xmath8 for the stars and gas.       galaxies : formation, galaxies : evolution, galaxies : structure
we investigate the quantum statistical properties of the light emitted by a quantum well interacting with squeezed light from a degenerate subthreshold optical parametric oscillator.   we obtain analytical solutions for the pertinent quantum langevin equations in the strong coupling and low excitation regimes. using these solutions   we calculate the intensity spectrum, autocorrelation function, quadrature squeezing for the fluorescent light.   we show that the fluorescent light exhibits bunching and quadrature squeezing.   we also show that the squeezed light leads to narrowing of the width of the spectrum of the fluorescent light.
we discuss convergence and coupling of markov chains, and present general relations between the transfer matrices describing these two processes.   we then analyze a recently developed local - patch algorithm, which computes rigorous upper bound for the coupling time of a markov chain for non - trivial statistical - mechanics models. using the `` coupling from the past '' protocol,   this allows one to exactly sample the underlying equilibrium distribution. for spin glasses in two and three spatial dimensions, the local - patch algorithm works at lower temperatures than previous exact - sampling methods.   we discuss variants of the algorithm which might allow one to reach, in three dimensions, the spin - glass transition temperature.   the algorithm can be adapted to hard - sphere models. for two - dimensional hard disks,   the algorithm allows us to draw exact samples at higher densities than previously possible.
by using the green - function concept of quantization of the electromagnetic field in dispersing and absorbing media, the quantized field in the presence of a dispersing and absorbing dielectric multilayer plate is studied.   three - dimensional input - output relations are derived for both amplitude operators in the @xmath0-space and the field operators in the coordinate space.   the conditions are discussed, under which the input - output relations can be expressed in terms of bosonic operators.   the theory applies to both ( effectively ) free fields and fields, created by active atomic sources inside and/or outside the plate, including also evanescent - field components.
thanks to global efforts over the past two decades, the phenomenon of neutrino oscillations is now well established. in ongoing experiments,   the parameters driving the oscillations are being determined with rapidly increasing precision.   yet there still are open issues that have implications going well beyond neutrino physics.   the next two decades are expected to bring definite answers to the neutrino - mass hierarchy and violation of charge - particle ( cp ) symmetry in neutrino oscillations.   the question of the mass hierarchy  whether the neutrino masses follow the pattern of the charged - lepton masses  is relevant for cosmology, astrophysics and unification theories.   on the other hand, cp violating oscillations have the potential to give an important, or event dominant, contribution to the matter - antimatter asymmetry in the universe.   for the success of future neutrino - oscillation studies it is, however, necessary to ensure a significant reduction of uncertainties, particularly those related to neutrino - energy reconstruction.   we discuss different sources of systematic uncertainties, paying special attention to those arising from nuclear effects and detector response. analyzing nuclear effects   we show the importance of developing accurate theoretical models, capable to provide truly quantitative description of neutrino cross sections, together with the relevance of their implementation in monte carlo generators and extensive testing against scattering data.   we also point out the fundamental role of efforts aiming to determine detector response in test - beam exposures.
a recently developed method [ a. shelankov and m. ozana, phys.   rev.   b * 61 *, 7077 ( 2000 ) ] is applied to investigate @xmath0-wave superconductors in the vicinity of ( rough ) surfaces. while this method allows the incorporation of arbitrary interfaces into the quasiclassical technique, we discuss, as examples, diffusive surfaces and boundaries with small tilted mirrors ( facets ).   the properties of the surface enter via the scattering matrix in the boundary condition for the quasiclassical green s function.   the diffusive surface is described by an ensemble of random scattering matrices.   we find that the fluctuations of the density of states around the average are small ; the zero bias conductance peak broadens with increasing disorder.   the faceted surface is described in the model where the scattering matrix couples @xmath1 in- and @xmath1 out - trajectories ( @xmath2 ).   no zero bias conductance peak is found for  surfaces ; the relation to the model of fogelstrm _ et al. _   [ phys.   rev.   lett. * 79 *, 281 ( 1997 ) ] is discussed.
we simulate neutrino production in a gamma - ray burst ( grb ) with the most detailed method to date.   we show that the highest energy neutrinos from grbs mainly come from kaons.   although there is little chance to detect such neutrinos, attempts of detection are very important to prove physical conditions in grbs.
a review of coherent phenomena in photoexcited semiconductors is presented. in particular,   two classes of phenomena are considered : on the one hand the role played by optically - induced phase coherence in the ultrafast spectroscopy of semiconductors ; on the other hand the coulomb - induced effects on the coherent optical response of low - dimensional structures.   all the phenomena discussed in the paper are analyzed in terms of a theoretical framework based on the density - matrix formalism. due to its generality  , this quantum - kinetic approach allows a realistic description of coherent as well as incoherent, i.e. phase - breaking, processes, thus providing quantitative information on the coupled coherent vs. incoherent carrier dynamics in photoexcited semiconductors.   the primary goal of the paper is to discuss the concept of quantum - mechanical phase coherence as well as its relevance and implications on semiconductor physics and technology. in particular  , we will discuss the dominant role played by optically induced phase coherence on the process of carrier photogeneration and relaxation in bulk systems.   we will then review typical field - induced coherent phenomena in semiconductor superlattices such as bloch oscillations and wannier - stark localization.   finally, we will discuss the dominant role played by coulomb correlation on the linear and non - linear optical spectra of realistic quantum - wire structures.    0.8 cm -0.8 cm 15.7 cm -1.cm    _ semiconductor science and technology _ + * review article on : *
it has been proposed that the noncommutative geometry of the `` fuzzy '' 2-sphere provides a nonperturbative regularization of scalar field theories.   this generalizes to compact khler   manifolds where simple field theories are regularized by the geometric quantization of the manifold.    in order to permit actual calculations and the comparison with other regularizations,   i describe the perturbation theory of these regularized models and propose an approximation technique for evaluation of the feynman diagrams.   i present example calculations of the simplest diagrams for the @xmath0 model on the spaces @xmath1, @xmath2, and @xmath3.   this regularization fails for noncompact spaces ; i give a brief dimensional analysis argument as to why this is so.   i also discuss the relevance of the topology of feynman diagrams to their ultra - violet and infra - red divergence behavior in this model.   l +   +
we review the ads / cft description of gauge theory plasmas for non - experts.   we discuss the low shear viscosity, jet quenching, and @xmath0-suppression, which are three major signatures for the quark - gluon plasma observed at rhic experiments.   based on invited talks presented at  frontiers in the physics of quark - gluon plasma " ( july 7 - 8 2006, riken ),  string theory and quantum field theory " ( sep.   12 - 16 2006, yitp ), the fall meeting 2006 of the physical society of japan ( sep.   20 - 22 2006, nara women s univ. ),  ads / cft and strongly coupled quark matter " ( nov.   21 - 22 2006, ccast ), ykis2006 ( nov.   20 - 28 2006, yitp ), a string theory workshop at rikkyo univ.   ( dec.   26 - 27 2006 ).
attractive colloidal particles can form a disordered elastic solid or gel when quenched into a two - phase region, if the volume fraction is sufficiently large.   when the interactions are comparable to thermal energies the stress - bearing network within the gel restructures over time as individual particle bonds break and reform.   typically, under gravity such weak gels show a prolonged period of either no or very slow settling, followed by a sudden and rapid collapse - a phenomenon known as delayed collapse.   the link between local bond breaking events and the macroscopic process of delayed collapse is not well understood. here   we summarize the main features of delayed collapse and discuss the microscopic processes which cause it.   we present a plausible model which connects the kinetics of bond breaking to gel collapse and test the model by exploring the effect of an applied external force on the stability of a gel.
d - term inflation is one of the most interesting and versatile models of inflation.   it is possible to implement naturally d - term inflation within high energy physics, as for example susy guts, sugra, or string theories.   d - term inflation avoids the @xmath0-problem, while in its standard form it always ends with the formation of cosmic strings.   given the recent three - year wmap data on the cosmic microwave background temperature anisotropies, we examine whether d - term inflation can be successfully implemented in non - minimal supergravity theories.   we show that for all our choices of khler potential, there exists a parameter space for which the predictions of d - term inflation are in agreement with the measurements.   the cosmic string contribution on the measured temperature anisotropies is always dominant, unless the superpotential coupling constant is fine tuned ; a result already obtained for d - term inflation within minimal supergravity. in conclusion, cosmic strings and their rle in the angular power spectrum can not be easily hidden by just considering a non - flat khler geometry.
the effect of projectile shape on cross sections and momentum distributions of fragments from heavy ion reactions is studied.   we propose a new approach that implements the underlying symmetries of each isotope with a few parameters directly in the density.   various densities and their nuclear structure are then analyzed in the reactions of @xmath0c and @xmath1li, @xmath1be, and @xmath1c on a carbon target.
it is already understood that the increasing observational evidence for an open universe may be reconciled with inflation if our horizon is contained inside one single huge bubble nucleated during the inflationary phase transition. in the scenario we present here,   the universe consists of infinitely many superhorizon bubbles, like our own, the distribution of which can be made to peak at @xmath0.   therefore, unlike the existing literature, we do not have to rely upon the anthropic principle nor upon special initial conditions.
thanks to s long exposures of the galactic plane, the two brightest soft gamma - ray repeaters, sgr 1806 - 20 and sgr 1900 + 14, have been monitored and studied in detail for the first time at hard - x / soft gamma rays.   this has produced a wealth of new scientific results, which we will review here. since sgr   1806 - 20 was particularly active during the last two years, more than 300 short bursts have been observed with   and their characteristics have been studied with unprecedented sensitivity in the 15 - 200 kev range.   a hardness - intensity anticorrelation within the bursts has been discovered and the overall number - intensity distribution of the bursts has been determined.   in addition, a particularly active state, during which  100 bursts were emitted in  10 minutes, has been observed on october 5 2004, indicating that the source activity was rapidly increasing.   this eventually led to the giant flare of december 27th 2004, for which a possible soft gamma - ray ( @xmath080 kev ) early afterglow has been detected.   the deep observations allowed us to discover the persistent emission in hard x - rays ( 20 - 150 kev ) from 1806 - 20 and 1900 + 14, the latter being in a quiescent state, and to directly compare the spectral characteristics of all magnetars ( two sgrs and three anomalous x - ray pulsars ) detected with.
we present @xmath0 optical images taken with ctio4m+mosaic of the 0.32 deg@xmath1 extended hubble deep field south.   this is one of four fields comprising the musyc survey, which is optimized for the study of galaxies at @xmath2, agn demographics, and galactic structure.   our methods used for astrometric calibration, weighted image combination, and photometric calibration in ab magnitudes are described.   we calculate corrected aperture photometry and its uncertainties and find through tests that these provide a significant improvement upon standard techniques.   our photometric catalog of 62968 objects is complete to a total magnitude of @xmath3, with @xmath4-band counts consistent with results from the literature.   we select @xmath5 lyman break galaxy ( lbg ) candidates from their @xmath6 colors and find a sky surface density of 1.4 arcmin@xmath7 and an angular correlation function @xmath8, consistent with previous findings that high - redshift lyman break galaxies reside in massive dark matter halos.   our images and catalogs are available at http://www.astro.yale.edu/musyc.
the current status of flavored dark matter is reviewed.   we discuss the main experimental constraints on models of flavored dark matter and survey some possible considerations which are relevant for the constructions of models.   we then review the application of existing flavor principles to dark matter, with an emphasis on minimal flavor violation, and discuss implications of flavored dark matter on collider phenomenology.
this paper studies the utility of the processes @xmath0, @xmath1, and @xmath2 in searching for sources of @xmath3 violation arising from energy scales beyond the production thresholds of planned future colliders. in the context of an effective lagrangian approach we consider the most general set of @xmath3 odd su(2 ) @xmath4 u(1 ) operators that give rise to genuinely quartic gauge boson couplings which can be probed in @xmath5 scattering processes at a @xmath6 collider.   we study each process in detail, emphasizing the complementary information that is obtained by varying the initial beam polarizations.   finally, we compare our results to other constraints in the literature on @xmath3 odd gauge boson interactions and quartic gauge boson couplings ; the search reaches obtained here are typically stronger and nicely complement previous studies which have focused primarily on @xmath7 boson, top quark, or higgs production.       .3 cm stanford linear accelerator center + stanford university + stanford ca 94309, usa +.3 cm
in this work we discuss a theory for entanglement generation, characterization and detection in fermionic two - particle interferometers at finite temperature.   the motivation for our work is provided by the recent experiment by the heiblum group, neder _ et al _, nature * 448 *, 333 ( 2007 ), realizing the two particle interferometer proposed by samuelsson, sukhorukov, and bttiker, phys.   rev.   lett. * 92 *, 026805 ( 2004 ).   the experiment displayed a clear two - particle aharonov - bohm effect, however with an amplitude suppressed due to finite temperature and dephasing.   this raised qualitative as well quantitative questions about entanglement production and detection in mesoscopic conductors at finite temperature.   as a response to these questions, in our recent work, samuelsson, neder, and bttiker, phys.   rev.   lett. * 102 *, 106804 ( 2009 ) we presented a general theory for finite temperature entanglement in mesoscopic conductors.   applied to the two - particle interferometer we showed that the emitted two - particle state in the experiment was clearly entangled.   moreover, we demonstrated that the entanglement of the reduced two - particle state, reconstructed from measurements of average currents and current cross correlations, constitutes a lower bound to the entanglement of the emitted state.   the present work provides an extended and more detailed discussion of these findings.
we analyze the effects of lepton asymmetry on neutrino oscillations and on cosmological nucleosynthesis with active - sterile oscillating neutrinos.   it is shown that small lepton asymmetries, @xmath0, whose direct kinetic effect on nucleosynthesis is negligible, still effect nucleosynthesis considerably through their influence on oscillating neutrinos.   two different cases of lepton asymmetry are discussed : an initially present and a dynamically generated in oscillations. _ dynamically generated in resonant oscillations asymmetry _ at small mixing angles suppresses oscillations, hence, the nucleosynthesis bounds on neutrino mass differences at small mixings are relaxed.   _ initially present asymmetry _ may suppress or enhance oscillations.   the enhancement is a result of interchanging resonances between neutrino and antineutrino ensembles due to resonance waves passing through the neutrino and antineutrino spectrum.   updated nucleosynthesis bounds on neutrino oscillation parameters accounting for lepton asymmetry are presented.
in this paper we present a very general theoretical framework for addressing fermionic superfluids over the entire range of bcs to bose einstein condensation ( bec ) crossover in the presence of population imbalance or spin polarization.   our emphasis is on providing a theory which reduces to the standard zero temperature mean field theories in the literature, but necessarily includes pairing fluctuation effects at non - zero temperature within a consistent framework.   physically, these effects are associated with the presence of pre - formed pairs ( or a fermionic pseudogap ) in the normal phase, and pair excitations of the condensate, in the superfluid phase.   we show how this finite @xmath0 theory of fermionic pair condensates bears many similarities to the condensation of point bosons. in the process   we examine three different types of condensate : the usual breached pair or sarma phase and both the one and two plane wave larkin- ovchinnikov, fulde - ferrell ( loff ) states.   the last of these has been discussed in the literature albeit only within a landau - ginzburg formalism, generally valid near @xmath1.   here we show how to arrive at the two plane wave loff state in the ground state as well as at general temperature @xmath0.
on the basis of physical considerations we propose a one  dimensional discrete lattice model for the density relaxation of granular materials under tapping. solving the difference equation numerically, we find a logarithmic time   dependence of the density relaxation.   this is in agreement with experimental results of knight @xmath0 @xmath1 [ phys.   rev.   e * 51 *, 3957(1995 ) ].   the origin of this anomalous relaxation is elucidated analytically by solving the equation of its continuum version asymptotically in time.   pacs numbers : 46.10.+z, 05.40.+j, 05.60.+w
we describe a new methodology for studying persistence of topological features across a family of spaces or point - cloud data sets, called zigzag persistence. building on classical results about quiver representations, zigzag persistence generalises the highly successful theory of persistent homology and addresses several situations which are not covered by that theory. in this paper   we develop theoretical and algorithmic foundations with a view towards applications in topological statistics.
hybrid inflation can be realised in low - energy effective string theory, as described using supergravity.   we find that the coupling of moduli to @xmath0-term hybrid inflation in supergravity leads to a slope and a curvature for the inflaton potential.   the @xmath1 and @xmath2 parameters receive contributions at tree and one loop level which are not compatible with slow roll inflation. furthermore the coupling to the moduli sector can even prevent inflation from ending at all.   we show that introducing shift symmetries in the inflationary sector and taking the moduli sector to be no - scale removes most of these problems.   if the moduli fields are fixed during inflation, as is usually assumed, it appears that viable slow - roll inflation can then be obtained with just one fine - tuning of the moduli sector parameters.   however, we show this is not a reasonable assumption, and that the small variation of the moduli fields during inflation gives a significant contribution to the effective inflaton potential.   this typically implies that @xmath3, although it may be possible to obtain smaller values with heavy fine - tuning.   _ keywords _ : inflation, string theory and cosmology
lattice molecule models are proposed in order to study statistical mechanics of glass transition in finite dimensions.   molecules in the models are represented by hard wang tiles and their density is controlled by a chemical potential.   an infinite series of irregular ground states are constructed theoretically. by defining a glass order parameter as a collection of the overlap with each ground state, a thermodynamic transition to a glass phase   is found in a stratified wang tiles model on a cubic lattice.
network epidemiology often assumes that the relationships defining the social network of a population are static.   the dynamics of relationships is only taken indirectly into account, by assuming that the relevant information to study epidemic spread is encoded in the network obtained by considering numbers of partners accumulated over periods of time roughly proportional to the infectious period of the disease at hand. on the other hand,   models explicitly including social dynamics are often too schematic to provide a reasonable representation of a real population, or so detailed that no general conclusions can be drawn from them. here   we present a model of social dynamics that is general enough that its parameters can be obtained by fitting data from surveys about sexual behaviour, but that can still be studied analytically, using mean field techniques.   this allows us to obtain some general results about epidemic spreading.   we show that using accumulated network data to estimate the static epidemic threshold leads to a significant underestimation of it.   we also show that, for a dynamic network, the relative epidemic threshold is an increasing function of the infectious period of the disease, implying that the static value is a lower bound to the real threshold.
this study proceeds with the development of the technique employing velocity gradients that were identified in ( @xcite, henceforth gl17 ) as a means of probing magnetic field in interstellar media.   we demonstrate a number of practical ways on improving the accuracy of tracing magnetic fields in diffuse interstellar media using velocity centroid gradients ( vcgs ). addressing the magnetic field tracing in super - alfvenic turbulence   we introduce the procedure of filtering low spatial frequencies, that enables magnetic field tracing in the situations when the kinetic energy of turbulent plasmas dominate its magnetic energy.   we propose the synergic way of of using vcgs together with intensity gradients ( igs ), synchrotron intensity gradients ( sigs ) as well as dust polarimetry.   we show that while the igs trace magnetic field worse than the vcgs, the deviations of the angle between the igs and vcgs trace the shocks in diffuse media.   similarly the perpendicular orientation of the vcgs and the sigs or to the dust polarimetry data trace the regions of gravitational collapse.   we demonstrate the utility of combining the vcgs, igs and polarimetry using galfa hi and planck polarimetry data.   we also provide an example of synergy of the vcgs and the sigs using the hi4pi full - sky hi survey together with the planck synchrotron intensity data.
the total kinetic energy release in the neutron induced fission of @xmath0u was measured ( using white spectrum neutrons from lansce ) for neutron energies from e@xmath1 = 3.2 to 50 mev. in this   energy range the average post - neutron total kinetic energy release drops from 167.4 @xmath2 0.7 to 162.1 @xmath2 0.8 mev, exhibiting a local dip near the second chance fission threshold.   the values and the slope of the tke vs. e@xmath1 agree with previous measurements but do disagree ( in magnitude ) with systematics.   the variances of the tke distributions are larger than expected and apart from structure near the second chance fission threshold, are invariant for the neutron energy range from 11 to 50 mev.   we also report the dependence of the total excitation energy in fission, txe, on neutron energy.
fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae ( pne ), reflection nebulae ( rne ) and hii regions. the tenuous nature of the gas in these environments precludes the formation of fullerene materials following known vaporization or combustion synthesis routes even on astronomical timescales.   we have studied the processing of hydrogenated amorphous carbon ( a - c : h or hac ) nano - particles and their specific derivative structures, which we name `` arophatics '', in the circumstellar environments of young, carbon - rich pne.   we find that uv - irradiation of such particles can result in the formation of fullerenes, consistent with the known physical conditions in pne and with available timescales.   = 1
we compute the one - loop anomalous dimension for the light cone distribution function of a heavy quark and solve the corresponding evolution equation analytically  . some implications of the results for inclusive @xmath0 decays are discussed.   hep - ph/9805297 + ttp 9816 + hd  thep 9818 +    * evolution of the light   cone distribution function for a heavy quark *    christopher balzereit and thomas mannel + _ institut fr theoretische teilchenphysik, universitt karlsruhe, + d   76128 karlsruhe, germany _   + wolfgang kilian + _ institut fr theoretische physik, universitt heidelberg, + d  69120 heidelberg, germany _
with the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. built on the recent remarkable progress in optical control of motional states of diamonds, here   we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. through quantum process tomography,   we demonstrate average teleportation fidelity @xmath0, clearly exceeding the classical limit of @xmath1.   the experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for optomechanical quantum control and quantum information science.
the parameters of the p - mode oscillations vary with solar activity.   such temporal variations provide insights for the study of the structural and dynamical changes occurring in the sun s interior throughout the solar cycle.   we present here a complete picture of the temporal variations of the global p - mode parameters ( excitation, damping, frequency, peak asymmetry, and rotational splitting ) over the entire solar cycle 23 and the beginning of cycle 24 as observed by the space - based, sun - as - a - star helioseismic golf and virgo instruments onboard soho.
we study the hydrodynamics of the a - b interface with finite curvature.   the interface tension is shown to enhance both the transition velocity and the amplitudes of second sound.   in addition, the magnetic signals emitted by the growing bubble are calculated, and the interaction between many growing bubbles is considered.   -10 pt 10 pt 1 in 0 in 0 in 0.75 in 6.375 true in    =    mathrm # 1#1    = 500    pacs - numbers : 67.57.-z, 67.55.fa itp - uh 11/93
we demonstrate the existence of complex solitary wave and periodic solutions of the kortweg de - vries ( kdv ) and modified kortweg de - vries ( mkdv ) equations.   the solutions of the kdv ( mkdv ) equation appear in complex - conjugate pairs and are even ( odd ) under the simultaneous actions of parity ( @xmath0 ) and time - reversal ( @xmath1 ) operations.   the corresponding localized solitons are hydrodynamic analogs of bloch soliton in magnetic system, with asymptotically vanishing intensity. the @xmath2-odd complex soliton solution is shown to be iso - spectrally connected to the fundamental @xmath3 solution through supersymmetry.
the freezing transition of hard spheres has been well described by various versions of density - functional theory ( dft ).   these theories should possess the close - packed crystal as a special limit, which represents an extreme testing ground for the quality of such liquid - state based theories.   we therefore study the predictions of dft for the structure and thermodynamics of the hard - sphere crystal in this limit.   we examine the ramakrishnan - yussouff ( ry ) approximation and two variants of the fundamental - measure theory ( fmt ) developed by rosenfeld and coworkers.   we allow for general shapes of the density peaks, going beyond the common gaussian approximation. in all cases   we find that, upon approaching close packing, the peak width vanishes proportionally to the free distance @xmath0 between the particles and the free energy depends logarithmically on @xmath0.   however, different peak shapes and next - to - leading contributions to the free energy result from the different approximate functionals. for the ry theory, within the gaussian approximation, we establish that the crystalline solutions form a closed loop with a stable and an unstable branch both connected to the close - packing point at @xmath1, consistent with the absence of a liquid - solid spinodal. that version of fmt that has previously been applied to freezing, predicts asymptotically step - like density profiles confined to the cells of self - consistent cell theory. but a recently suggested improved version which employs tensor weighted densities yields wider and almost gaussian peaks which are shown to be in very good agreement with computer simulations.
the abstract framework of quantum mechanics ( qm ) causes the well - known weirdness, which leads to the field of foundation of qm.   we constructed the new concept, i.e., _ scope _, to lay the foundation of quantum coherence and openness, also the principles of superposition and entanglement.   we studied analytically and quantitatively the quantum correlations and information, also we discussed the physical essence of the existed entanglement measures.   we compared with several other approaches to the foundation of qm, and we stated that the concept of scope is unique and has not been demonstrated before.
the successful deployment of lte heterogeneous networks ( hetnets ) depends crucially on the inter - cell interference ( ici ) management. among ici coordination schemes, fractional frequency reuse ( ffr )   is considered as an efficient technique well - suited to ofdma - based hetnets.   two coupled questions in this context are : 1 ) how to associate users to appropriate base - stations considering the long list of available candidate cells, and 2 ) how to allocate frequency resources among multiple cells. in this paper  , we treat the multi - cell frequency allocation as frequency partitioning among multiple _ reuse patterns _, and develop a novel algorithm to solve these two coupled questions in a joint manner.   we also provide practical criterion to select the set of essential candidate patterns from all possible patterns.   results show that the proposed joint strategy improves both the cell - edge user and overall network throughput.
_ xmm - newton _ has been performing comprehensive studies of x - ray bright rs cvn binaries in its calibration and guaranteed time programs.   we present results from ongoing investigations in the context of a systematic study of coronal emission from rs cvns.   we concentrate in this paper on coronal abundances and investigate the abundance pattern in rs cvn binaries as a function of activity and average temperature. a transition from an inverse first ionization potential ( fip ) effect towards an absence of a clear trend   is found in intermediately active rs cvn systems.   this scheme corresponds well into the long - term evolution from an ifip to a fip effect found in solar analogs.   we further study variations in the elemental abundances during a large flare.
viable models of modified gravity which satisfy both local as well as cosmological tests are investigated.   it is demonstrated that some versions of such highly non - linear models exhibit multiply de sitter universe solutions, which often appear in pairs, being one of them stable and the other unstable.   it is explicitly shown that, for some values of the parameters, it is possible to find several de sitter spaces ( as a rule, numerically ) ; one of them may serve for the inflationary stage, while the other can be used for the description of the dark energy epoch.   the numerical evolution of the effective equation of state parameter is also presented, showing that these models can be considered as natural candidates for the unification of early - time inflation with late - time acceleration through ds critical points. moreover,   based on the de sitter solutions, multiply sds universes are constructed which might also appear at the ( pre-)inflationary stage.   their thermodynamics are studied and free energies are compared.   = 5000
we carry out a comparative study of electronic properties of 2d electron gas ( 2deg ) in a magnetic field of an infinitesimally thin solenoid with relativistic dispersion as in graphene and quadratic dispersion as in semiconducting heterostructures.   the problem of ambiguity of the zero mode solutions of the dirac equation is treated by considering of a finite radius flux tube which allows to select unique solutions associated with each @xmath0 point of graphene s brillouin zone.   then this radius is allowed to go to zero. on the base of the obtained in this case analytical solutions in the aharonov - bohm potential the local and total density of states ( dos ) are calculated.   it is shown that in the case of graphene there is an excess of ldos near the vortex, while in 2deg the ldos is depleted.   this results in excess of the induced by the vortex dos in graphene and in its depletion in 2deg.   we discuss the application of the results for the local density of states for the scanning tunneling spectroscopy done on graphene.
based on observations performed with the pulkovo normal astrograph in 2008 - 2015 and data from sky surveys ( dss, 2mass, sdss dr12, wise ), we have investigated the motions of 1308 stars with proper motions larger than @xmath0 down to magnitude 17.   the main idea of our search for binary stars based on this material is reduced to comparing the quasi - mean ( poss2-poss1 ; an epoch difference of @xmath150 yr ) and quasi - instantaneous ( 2mass, sdss, wise, pulkovo ; an epoch difference of @xmath110 yr ) proper motions.   if the difference is statistically significant compared to the proper motion errors, then the object may be considered as a @xmath2-binary candidate.   one hundred and twenty one stars from among those included in the observational program satisfy this requirement.   additional confirmations of binarity for a number of stars have been obtained by comparing the calculated proper motions with the data from several programs of stellar trigonometric parallax determinations and by analyzing the asymmetry of stellar images on sky - survey ccd frames.   analysis of the highly accurate sdss photometric data for four stars ( j0656 + 3827, j0838 + 3940, j1229 + 5332, j2330 + 4639 ) allows us to reach a conclusion about the probability that these @xmath2 binaries are white dwarf + m dwarf pairs.   + * pacs codes : * 97.10.wn 98.35.pr 97.80af + galactic solar neighborhoods, stars with large proper motions, astrometric binaries.
in the previous study ( hiremath 2006a ), the solar cycle is modeled as a forced and damped harmonic oscillator and from all the 22 cycles ( 1755 - 1996 ), long - term amplitudes, frequencies, phases and decay factor are obtained. using these physical parameters of the previous 22 solar cycles and by an _   autoregressive model _  , we predict the amplitude and period of the future fifteen solar cycles.   predicted amplitude of the present solar cycle ( 23 ) matches very well with the observations.   the period of the present cycle is found to be 11.73 years. with these encouraging results,   we also predict the profiles of future 15 solar cycles.   important predictions are : ( i ) the period and amplitude of the cycle 24 are 9.34 years and 110 ( @xmath0 ), ( ii ) the period and amplitude of the cycle 25 are 12.49 years and 110 ( @xmath1 11 ), ( iii ) during the cycles 26 ( 2030 - 2042 ad ), 27 ( 2042 - 2054 ad ), 34 ( 2118 - 2127 ad ), 37 ( 2152 - 2163 ad ) and 38 ( 2163 - 2176 ad ), the sun might experience a very high sunspot activity, ( iv ) the sun might also experience a very low ( around 60 ) sunspot activity during cycle 31 ( 2089 - 2100 ad ) and, ( v ) length of the solar cycles vary from 8.65 yrs for the cycle 33 to maximum of 13.07 yrs for the cycle 35.
we propose a stochastic map model of economic dynamics. in the last decade  , an array of observations in economics has been investigated in the econophysics literature, a major example being the universal features of inequality in terms of income and wealth.   another area of inquiry is the formation of opinion in a society.   the proposed model attempts to produce positively skewed distributions and the power law distributions as has been observed in the real data of income and wealth. also, it shows a non - trivial phase transition in the opinion of a society ( opinion formation ).   a number of physical models also generates similar results.   in particular, the kinetic exchange models have been especially successful in this regard.   therefore, we compare the results obtained from these two approaches and discuss a number of new features and drawbacks of this model.    _ _
a null fluid with radial pressure is proposed as the source generating vaidya spacetime.   the fluid is anisotropic with no transversal pressures and @xmath0 as its equation of state, where @xmath1 is the isotropic pressure and @xmath2 is the energy density.   the radial energy flux is inward directed when @xmath3 and the total energy flow crossing a surface of constant @xmath4 resembles the brown - york quasilocal energy.   a modified vaidya metric removes the singularity at the origin and the corresponding qle is investigated in terms of both @xmath4 and the mass @xmath5 of the object. +   * keywords * : radial pressure, apparent horizon, quasilocal energy, null fluid.
using the all - sky rosat soft x - ray and 408-mhz radio continuum data, we show that the north polar spur and its western and southern counter - spurs draw a giant dumbbell - shape necked at the galactic plane.   we interpret these features as due to a shock front originating from a starburst 15 million years ago with a total energy of the order of @xmath0 ergs or @xmath1 type ii supernovae.   we simulate all - sky distributions of radio continuum and soft x - ray intensities based on the bipolar - hyper - shell galactic center starburst model.   the simulations can well reproduce the radio nps and related spurs, as well as radio spurs in the tangential directions of spiral arms.   simulated x - ray maps in 0.25, 0.75 and 1.5 kev bands reproduce the rosat x - ray nps, its western and southern counter - spurs, and the absorption layer along the galactic plane.   we propose to use the rosat all - sky maps to probe the physics of gas in the halo - intergalactic interface, and to directly date and measure the energy of a recent galactic center starburst.    v    = -5 mm = -1 cm = -5 mm
in antiferromagnetically coupled superlattices grown on ( 001 ) faces of cubic substrates, e.g. based on materials combinations as co / cu, fe / si, co / cr, or fe / cr, the magnetic states evolve under competing influence of bilinear and biquadratic exchange interactions, surface - enhanced four - fold in - plane anisotropy, and specific finite - size effects. using phenomenological ( micromagnetic ) theory,   a comprehensive survey of the magnetic states and reorientation transitions has been carried out for multilayer systems with even number of ferromagnetic sub - layers and magnetizations in the plane. in two - layer systems ( @xmath0 )   the phase diagrams in dependence on components of the applied field in the plane include `` swallow - tail '' type regions of ( metastable ) multistate co - existence and a number of continuous and discontinuous reorientation transitions induced by radial and transversal components of the applied field. in multilayers ( @xmath1 )   noncollinear states are spatially inhomogeneous with magnetization varying across the multilayer stack. for weak four - fold anisotropy the magnetic states under influence of an applied field evolve by a complex continuous reorientation into the saturated state. at higher   anisotropy they transform into various inhomogeneous and asymmetric structures.   the discontinuous transitions between the magnetic states in these two - layers and multilayers are characterized by broad ranges of multi - phase coexistence of the ( metastable ) states and give rise to specific transitional domain structures.   donetsk institute for physics and technology, 340114 donetsk, ukraine
the high spatial and spectral resolution offered by the new generation of infrared spectrometers at eso is optimally suited for the observational study of outflows from young stellar objects.   models of interstellar shock waves would benefit from observations of spectrally resolved line profiles.   this applies also to attempts of measuring the rotation rates of jets very close to their driving source, which in general suffer considerable extinction.   observations of forbidden lines of ionised iron, , could be used to accomplish this.   the possibility of using rotational lines of molecular hydrogen, h@xmath0, to study the temporal evolution of outflow and disk gas is discussed.   similarly, high resolution ir observations of fluorescent water lines, h@xmath0o, open up the possibility to access outflow and disk water from the ground.
calorimetry at future linear colliders could be based on a particle flow approach where granularity is the key to high jet energy resolution. among different technologies, micromegas chambers with 1@xmath0 pad segmentation   are studied for the active medium of a hadronic calorimeter.   a chamber of 1m@xmath1 with 9216 channels read out by a low noise front - end asic called microroc has recently been constructed and tested.   chamber design, asic circuitry and preliminary test beam results are reported.
_ suzaku _ has, for the first time, enabled the hard x - ray variability of the seyfert 1 galaxy mcg6 - 30 - 15 to be measured.   the variability in the 1445  kev band, which is dominated by a strong reflection hump, is quenched relative to that at a few kev.   this directly demonstrates that the whole reflection spectrum is much less variable than the power - law continuum.   the broadband spectral variability can be decomposed into two components  a highly variable power - law and constant reflection  as previously inferred from other observations in the 210  kev band.   the strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii.   our results are consistent with the predictions of the light bending model which invokes the very strong gravitational effects expected very close to a rapidly spinning black hole.   ps.
we present a theory of single - magnet flowmeter for liquid metals and compare it with experimental results.   the flowmeter consists of a freely rotating permanent magnet, which is magnetized perpendicularly to the axle it is mounted on.   when such a magnet is placed close to a tube carrying liquid metal flow, it rotates so that the driving torque due to the eddy currents induced by the flow is balanced by the braking torque induced by the rotation itself.   the equilibrium rotation rate, which varies directly with the flow velocity and inversely with the distance between the magnet and the layer, is affected neither by the electrical conductivity of the metal nor by the magnet strength.   we obtain simple analytical solutions for the force and torque on slowly moving and rotating magnets due to eddy currents in a layer of infinite horizontal extent.   the predicted equilibrium rotation rates qualitatively agree with the magnet rotation rate measured on a liquid sodium flow in stainless steel duct.
we study the interaction between low - lying transverse collective oscillations and thermal excitations of an elongated bose - einstein condensate by means of perturbation theory.   we consider a cylindrically trapped condensate and calculate the transverse elementary excitations at zero temperature by solving the linearized gross - pitaevskii equations in two dimensions.   we use them to calculate the matrix elements between thermal excited states coupled with the quasi-2d collective modes.   the landau damping of transverse collective modes is investigated as a function of temperature. at low temperatures, the damping rate due to the landau decay mechanism is in agreement with the experimental data for the decay of the transverse quadrupole mode, but it is too small to explain the slow experimental decay of the transverse breathing mode.   the reason for this discrepancy is discussed.
the pairing hamiltonian constitutes an important approximation in many- body systems, it is exactly soluble and quantum integrable. on the other hand, the continuum single particle level density ( cspld ) contains information about the continuum energy spectrum.   the question whether one can use the hamiltonian with constant pairing strength for correlations in the continuum is still unanswered. in this paper   we generalize the richardson exact solution for the pairing hamiltonian including correlations in the continuum.   the resonant and non - resonant continuum are included through the cspld.   the resonant correlations are made explicit by using the cauchy theorem.   low lying states with seniority zero and two are calculated for the even carbon isotopes.   we conclude that energy levels can indeed be calculated with constant pairing in the continuum using the cspld.   it is found that the nucleus @xmath0c is unbound.   the real and complex energy representation of the continuum is developed and their differences are shown.   the trajectory of the pair energies in the continuum for the nucleus @xmath1c is shown.
a very high activity of cygnus x-1 on 1999 april 19 - 21 was recorded by batse large area detectors onboard the _ compton gamma - ray observatory ( cgro)_. the peak luminosity was one order of magnitude higher than the normal luminosity of cyg x-1.   this fact can be critical for models of the hard state of cyg x-1.   the longest outburst lasted @xmath0  s and demonstrated very unusual temporal and spectral behavior which indicates the presence of two emission components.   one component is relatively soft ( with a cutoff below @xmath1 ) and highly variable, and the other one is hard ( extending above 100 kev ), with much slower variability.
we compare our pion production results with recent miniboone data measured in mineral oil.   our total cross sections lie below experimental data for neutrino energies above 1gev.   differential cross sections show our model produces too few high energy pions in the forward direction as compared to data.   the agreement with experiment improves by artificially removing pion final state interaction.
rotational brownian motion of colloidal magnetic particles in ferrofluids under the influence of an oscillating external magnetic field is investigated.   it is shown that for a suitable time dependence of the magnetic field, a noise induced rotation of the ferromagnetic particles due to rectification of thermal fluctuations takes place. via viscous coupling, the associated angular momentum is transferred from the magnetic nano - particles to the carrier liquid and can then be measured as macroscopic torque on the fluid sample.   a thorough theoretical analysis of the effect in terms of symmetry considerations, analytical approximations, and numerical solutions is given which is in accordance with recent experimental findings.
it is demonstrated that strong laser pulses can introduce torsional motion in the axially chiral molecule 3,5-diflouro-3,5-dibromo - biphenyl ( dfdbrbph ).   a nanosecond laser pulse spatially aligns the stereogenic carbon - carbon ( c - c ) bond axis allowing a perpendicularly polarized, intense femtosecond pulse to initiate torsional motion accompanied by a rotation about the fixed axis.   we monitor the induced motion by femtosecond time - resolved coulomb explosion imaging.   our theoretical analysis corroborates the experimental findings and on the basis of these results we discuss future applications of laser induced torsion, viz., time - resolved studies of de - racemization and laser controlled molecular junctions based on molecules with torsion.
klein - gordon and dirac equations are the motion equations for relativistic particles with spin 0 ( so - called scalar particles ) and 1/2 ( electron / positron ) respectively. for a free particle,   the dirac equation is derived from the klein - gordon equation by taking its square root in a bi - quaternionic formalism fully justified by the first principles of the scale relativity theory.   this is no more true when an external electro - magnetic field comes into play.   if one tries to derive the electro - magnetic dirac equation in a manner analogous to the one used when this field is absent, one obtains an additional term which is the relativistic analogue of the spin - magnetic field coupling term encountered in the pauli equation, valid for a non - relativistic particle with spin 1/2.   there is however a method to recover the standard form of the electro - magnetic dirac equation, with no additional term, which amounts modifying the way both covariances involved here, quantum and scale, are implemented. without going into technical details,   it will be shown how these results suggest this last method is based on more profound roots of the scale relativity theory since it encompasses naturally the spin - charge coupling.
our formal understanding of the inductive bias that drives the success of convolutional networks on computer vision tasks is limited.   in particular, it is unclear what makes hypotheses spaces born from convolution and pooling operations so suitable for natural images. in this paper   we study the ability of convolutional networks to model correlations among regions of their input.   we theoretically analyze convolutional arithmetic circuits, and empirically validate our findings on other types of convolutional networks as well.   correlations are formalized through the notion of separation rank, which for a given partition of the input, measures how far a function is from being separable. we show that a polynomially sized deep network supports exponentially high separation ranks for certain input partitions, while being limited to polynomial separation ranks for others.   the network s pooling geometry effectively determines which input partitions are favored, thus serves as a means for controlling the inductive bias.   contiguous pooling windows as commonly employed in practice favor interleaved partitions over coarse ones, orienting the inductive bias towards the statistics of natural images.   other pooling schemes lead to different preferences, and this allows tailoring the network to data that departs from the usual domain of natural imagery.   in addition to analyzing deep networks, we show that shallow ones support only linear separation ranks, and by this gain insight into the benefit of functions brought forth by depth   they are able to efficiently model strong correlation under favored partitions of the input.
the influence of the size and shape of a dispersing and absorbing dielectric body on the local - field corrected spontaneous - decay of an excited atom embedded in the body is studied on the basis of the real - cavity model. by means of a born expansion of the green tensor of the system   it is shown that to linear order in the susceptibility of the body the decay rate exactly follows toma s formula found for the special case of an atom at the center of a homogeneous dielectric sphere [ phys.   rev.   a * 63 *, 053811 ( 2001 ) ].   it is further shown that for an atom situated at the interior of an arbitrary dielectric body this formula remains valid beyond the linear order.   the case of an atom embedded in a weakly polarizable sphere is discussed in detail.
we study the characteristics of the light generated by few emitters in a cavity at strong light - matter coupling. by means of the glauber @xmath0-function   we can identify clearly distinguished parameter regimes with super - poissonian and sub - poissonian photon statistics.   we establish a relation between the emission characteristics for one and multiple emitters, and explain its origin in terms of the photon - dressed emitter states.   cooperative effects lead to the generation of nonclassical light already at reduced light - matter coupling if the number of emitters is increased.   our results are obtained with a full input - output formalism and master equation valid also at strong light - matter coupling.   we compare the behavior obtained with and without counter - rotating light - matter interaction terms in the hamiltonian, and find that the generation of nonclassical light is robust against such modifications.   finally, we contrast our findings with the predictions of the quantum optical master equation and find that it fails entirely at predicting regimes with different photon statistics.
* purpose * : manipulation of the radio - sensitivity of the nucleotide - base driven by the spin blockade mechanism of diffusive free radicals against ionizing radiation. + * materials and methods * : we theoretically propose a mechanism which uses the simultaneous application of circularly polarized light and an external magnetic field to control the polarization of the free radicals and create s=1 electron - hole spin excitations ( excitons ) on nucleotide - base.   we deploy an ab - initio molecular dynamics model to calculate the characteristic parameters of the light needed for optical transitions. + * results * : as a specific example, we present the numerical results calculated for a guanine, in the presence of an oh free radical. to increase the radio - resistivity of this system, a blue light source for the optical pumping and induction of excitons on guanine can be used.   + * conclusions * : the effect of spin - injection on the formation of a free energy barrier in diffusion controlled chemical reaction pathways leads to the control of radiation - induced base damage.   the proposed method allows us to manipulate and partially suppress the damage induced by ionizing radiation.
lognormality was found experimentally for coarse - grained squared turbulence velocity and velocity increment when the coarsening scale is comparable to the correlation scale of the velocity ( mouri _ et al.   _ phys.   fluids * 21 *, 065107, 2009 ).   we investigate this large - scale lognormality by using a simple stochastic process with correlation, the ornstein - uhlenbeck ( ou ) process.   it is shown that the ou process has a similar large - scale lognormality, which is studied numerically and analytically.
the proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold.   results for the @xmath0c, @xmath1o and @xmath2ca nuclei are presented.   the sensitivity of various observables to final state interaction, meson exchange currents and short range correlations is analyzed.   we found relevant effects due to the virtual excitation of the @xmath3 resonance.
we present vlt low resolution spectroscopy of the neutron star x - ray transient xte j2123 - 058 during its quiescent state.   our data reveal the presence of a k7v companion which contributes 77 % to the total flux at @xmath06300 and orbits the neutron star at @xmath1 km s@xmath2.   contrary to other soft x - ray transients ( sxts ), the @xmath3 emission is almost exactly in antiphase with the velocity curve of the optical companion. using the light - center technique we obtain @xmath4 km s@xmath2 and hence @xmath5.   this, combined with a previous determination of the inclination angle ( @xmath6 ) yields @xmath7 m@xmath8 and @xmath9 m@xmath8.   @xmath10 agrees well with the observed spectral type.   doppler tomography of the h@xmath11 emission shows a non - symmetric accretion disc distribution mimicking that seen in sw sex stars.   although we find a large systemic velocity of -110 @xmath12 km s@xmath2 this value is consistent with the galactic rotation velocity at the position of j2123 - 058, and hence a halo origin.   the formation scenario of j2123 - 058 is still unresolved.   stars : accretion, accretion discs  binaries : close  stars : individual : xte  j2123058  x - rays : stars.
we present the results of a series of one - dimensional n - body and hydrodynamical simulations which have been used for testing the different clustering properties of baryonic and dark matter in an expanding background.   initial gaussian random density perturbations with a power - law spectrum @xmath0 are assumed.   we analyse the distribution of density fluctuations and thermodynamical quantities for different spectral indices @xmath1 and discuss the statistical properties of clustering in the corresponding simulations. at large scales   the final distribution of the two components is very similar while at small scales the dark matter presents a lumpiness which is not found in the baryonic matter.   the amplitude of density fluctuations in each component depends on the spectral index @xmath1 and only for @xmath2 the amplitude of baryonic density fluctuations is larger than that in the dark component.   this result is also confirmed by the behaviour of the bias factor, defined as the ratio between the r.m.s of baryonic and dark matter fluctuations at different scales : while for @xmath3 it is always less than unity except at very large scales where it tends to one, for @xmath2 it is above 1.4 at all scales.   all simulations show also that there is not an exact correspondence between the positions of largest peaks in dark and baryonic components, as confirmed by a cross - correlation analysis.   the final temperatures depend on the initial spectral index : the highest values are obtained for @xmath2 and are in proximity of high density regions.   galaxies : clustering  galaxies : formation  large - scale structure of universe
cyclotron decay and absorption rates have been well studied in the literature, focusing primarily on spectral, angular and polarization dependence.   astrophysical applications usually do not require retention of information on the electron spin state, and these are normally averaged in obtaining the requisite rates. in magnetic fields, higher order quantum processes such as compton scattering become resonant at the cyclotron frequency and its harmonics, with the resonances being formally divergent.   such divergences are usually eliminated by accounting for the finite lifetimes of excited landau states.   this practice requires the use of spin - dependent cyclotron rates in order to obtain accurate determinations of process rates very near cyclotronic resonances, the phase space domain most relevant for certain applications to pulsar models. this paper develops previous results in the literature to obtain compact analytic expressions for cyclotron decay rates / widths in terms of a series of legendre functions of the second kind ; these expressions can be expediently used in astrophysical models.   the rates are derived using two popular eigenstate formalisms, namely that due to sokolov and ternov, and that due to johnson and lippmann.   these constitute two sets of eigenfunctions of the dirac equation that diagonalize different operators, and accordingly yield different spin - dependent cyclotron rates.   this paper illustrates the attractive lorentz transformation characteristics of the sokolov and ternov formulation, which is another reason why it is preferable when electron spin information must be explicitly retained.
with the appearance of superpower laser sources of relativistic / ultrarelativistic intensities in the last decade, the laser - qed - vacuum - matter interaction physics has entered a new phase that makes real the observation of many nonlinear quantum electrodynamic ( qed ) and classical - quantum- mechanical phenomena revealed more than fore - five decades ago, serious advance in new generation of laser - plasma accelerators of ultrahigh energies, nuclear fusion etc.   hence, the present review article will help explorers - experimentalists in this field to attract attention on the fundamental properties and peculiarities of the dynamics of induced free - free transitions at high and superhigh intensities of stimulated radiation fields. in this connection it is of special interest the induced cherenkov, compton, undulator / wiggler coherent processes, as well as cyclotron resonance in a medium  possessing with nonlinear resonances of threshold nature and leading to many important nonlinear effects or applications, which are considered in this review.
a proof that continuous time quantum walks are universal for quantum computation, using unweighted graphs of low degree, has recently been presented by @xcite .   we present a version based instead on the discrete time quantum walk.   we show the discrete time quantum walk is able to implement the same universal gate set and thus both discrete and continuous time quantum walks are computational primitives.   additionally we give a set of components on which the discrete time quantum walk provides perfect state transfer.
the behavior of interacting populations typically displays irregular temporal and spatial patterns that are difficult to reconcile with an underlying deterministic dynamics.   a classical example is the heterogeneous distribution of plankton communities, which has been observed to be patchy over a wide range of spatial and temporal scales. here  , we use plankton communities as prototype systems to present theoretical approaches for the analysis of the combined effects of turbulent advection and stochastic growth in the spatiotemporal dynamics of the population.   incorporation of these two factors into mathematical models brings an extra level of realism to the description and leads to better agreement with experimental data than that of previously proposed models based on reaction - diffusion equations.
rigorous pointwise asymptotics are established for semiclassical soliton ensembles ( sses ) of the focusing nonlinear schrdinger equation using techniques of asymptotic analysis of matrix riemann - hilbert problems.   the accumulation of poles in the eigenfunction is handled using a new method in which the residues are simultaneously interpolated at the poles by two distinct interpolants.   the results justify the wkb approximation for the nonselfadjoint zakharov - shabat operator with real - analytic, bell - shaped, even potentials.   the new technique introduced in this paper is applicable to other problems as well : ( i ) it can be used to provide a unified treatment by riemann - hilbert methods of the zero - dispersion limit of the korteweg - de vries equation with negative ( soliton generating ) initial data as studied by lax, levermore, and venakides, and ( ii ) it allows one to compute rigorous strong asymptotics for systems of discrete orthogonal polynomials.
we present spatially resolved alma observations of the co @xmath0 emission line in two massive galaxies at @xmath1 on the star - forming main sequence.   both galaxies have compact dusty star - forming cores with effective radii of @xmath2 kpc and @xmath3 kpc in the 870 @xmath4 m continuum emission.   the spatial extent of star - forming molecular gas is also compact with @xmath5 kpc and @xmath6 kpc, but more extended than the dust emission. interpreting the observed position - velocity diagrams with dynamical models, we find the starburst cores to be rotation - dominated with the ratio of the maximum rotation velocity to the local velocity dispersion of @xmath7 ( @xmath8 km s@xmath9 ) and @xmath10 ( @xmath11 km s@xmath9 ). given that the descendants of these massive galaxies in the local universe are likely ellipticals with @xmath12 nearly an order of magnitude lower  , the rapidly rotating galaxies would lose significant net angular momentum in the intervening time.   the comparisons among dynamical, stellar, gas, and dust mass suggest that the starburst co - to - h@xmath13 conversion factor of @xmath14 ( k km s@xmath9pc@xmath15)@xmath9 is appropriate in the spatially resolved cores.   the dense cores are likely to be formed in extreme environments similar to the central regions of local ultraluminous infrared galaxies.   our work also demonstrates that a combination of medium - resolution co and high - resolution dust continuum observations is a powerful tool for characterizing the dynamical state of molecular gas in distant galaxies.
observations of gamma - ray bursts by the fermi satellite, capable of detecting photons in a very broad energy band : 8kev to @xmath0300gev, have opened a new window for the study of these enigmatic explosions.   it is widely assumed that photons of energy larger than 100 mev are produced by the same source that generated lower energy photons  at least whenever the shape of the spectrum is a band function.   we report here a surprising result  the fermi data for a bright burst, grb 080916c, unambiguously shows that the high energy photons ( @xmath1mev ) were generated in the external shock via the synchrotron process, and the lower energy photons had a distinctly different source. the magnetic field in the region where high energy photons were produced ( and also the late time afterglow emission region ) is found to be consistent with shock compressed magnetic field of the circum - stellar medium.   this result sheds light on the important question of the origin of magnetic fields required for gamma - ray burst afterglows.   the external shock model for high energy radiation makes a firm prediction that can be tested with existing and future observations.   radiation mechanisms : non - thermal - methods : analytical - gamma - rays : bursts, theory
symplectic integration methods based on operator splitting are well established in many branches of science. for hamiltonian systems which split in more than two parts,   symplectic methods of higher order have been studied in detail only for a few special cases. in this work,   we present and compare different ways to construct high order symplectic schemes for general hamiltonian systems that can be split in three integrable parts.   we use these techniques to numerically solve the equations of motion for a simple toy model, as well as the disordered discrete nonlinear schrdinger equation.   we thereby compare the efficiency of symplectic and non - symplectic integration methods.   our results show that the new symplectic schemes are superior to the other tested methods, with respect to both long term energy conservation and computational time requirements.   numerical methods, symplectic integrators, hamiltonian systems, dynamics of wave propagation, disordered systems, three part splitting.
the far  from  equilibrium low  temperature dynamics of ultra - thin magnetic films is analyzed by using monte carlo numerical simulations on a two dimensional ising model with competing exchange ( @xmath0 ) and dipolar ( @xmath1 ) interactions.   in particular, we focus our attention on the low temperature region of the @xmath2 phase diagram ( where @xmath3 ) for the range of values of @xmath4 where striped phases with widths @xmath5 ( @xmath6 ) and @xmath7 ( @xmath8 ) are present. the presence of metastable states of the phase @xmath8 in the region where the phase @xmath6 is the thermodynamically stable one and viceversa was established recently. in this work   we show that the presence of these metastable states appears as a blocking mechanism that slows the dynamics of magnetic domains growth when the system is quenched from a high temperature state to a low temperature state in the region of metastability.
we present the gamma - ray observations in the energy range 50  mev - 10  gev of the supernova remnant ( snr ) w44, one of the most interesting systems for studying cosmic - ray production.   w44 is an intermediate - age snr ( @xmath0  years ) and its ejecta expand in a dense medium as shown by a prominent radio shell, nearby molecular clouds, and bright  emitting regions.   we extend our gamma - ray analysis to energies substantially lower than previous measurements which could not conclusively establish the nature of the radiation.   we find that gamma - ray emission matches remarkably well both the position and shape of the inner snr shocked plasma.   furthermore, the gamma - ray spectrum shows a prominent peak near 1  gev with a clear decrement at energies below a few hundreds of mev as expected from neutral pion decay.   here we demonstrate that : ( 1 ) hadron - dominated models are consistent with all w44 multiwavelength constraints derived from radio, optical, x - ray, and gamma - ray observations ; ( 2 ) to explain simultaneously the well - constrained gamma - ray and radio spectra, and require a circumstellar density much larger than the value derived from observations ;
we propose a novel method to constrain the spatial extent of dust around galaxies through the measurement of dust temperature.   our method combines the dust emission of galaxies from far - infrared ( fir ) image stacking analysis and the quasar reddening due to the dust absorption around galaxies. as a specific application of our method  , we use the stacked fir emission profiles of sdss photometric galaxies over the _ iras _ @xmath0 map, and the recent measurement of the sdss galaxy - quasar cross - correlation.   if we adopt a single - temperature dust model, the resulting temperature is around 18k, which is consistent with a typical dust temperature for a central part of galaxies. if we assume an additional dust component with much lower temperature, the current data imply the temperature of the galactic dust needs to be higher, 20k to 30k.   since the model of the density and temperature distribution of dust adopted in the current paper is very simple, we can not draw any strong conclusion at this point.   nevertheless our novel method with the elaborated theoretical model and multi - band measurement of dust will offer an interesting constraint on the statistical nature of galactic dust.   dust  extinction, reddening  large - scale structures  galaxies
the pulsar igr j16393 - 4643 belongs to a class of highly absorbed supergiant hmxbs, characterised by very high column density of absorbing matter.   we present the results of the simultaneous broad - band pulsation and spectrum analysis, from a 44 kilosec _ suzaku _   observation of the source. the orbital intensity profile created with the _ swift - bat _   light - curve shows an indication of igr j16393 - 4643 being an eclipsing system with a short eclipse semi - angle @xmath0 17@xmath1. for a supergiant companion star with a 20 r@xmath2 radius, this implies an inclination of the orbital plane in the range of 39@xmath1 - 57@xmath1, whereas for a main sequence b star as the companion with a 10 r@xmath2 radius, the inclination of the orbital plane is in the range of 60@xmath1 - 77@xmath1.   pulse profiles created for different energy bands, have complex morphology which shows some energy dependence and increases in pulse fraction with energy.   we have also investigated broad - band spectral characteristics, for phase averaged and resolving the pulse phase into peak phase and trough phase.   the phase averaged spectrum has a very high n@xmath3 @xmath4 ) and is described by power - law ( @xmath5 0.9 ) with a high energy cut - off above 20 kev.   we find a change in the spectral index in the peak phase and trough phase, implying an underlying change in the source spectrum.   x - rays : binaries - x - rays : individual : igr j16393 - 4643 - x - rays : stars - stars : neutron
we explore the electromagnetic gauge invariance of the hadron tensor of the drell - yan process with one transversely polarized hadron.   the special role is played by the contour gauge for gluon fields.   the prescription for the gluonic pole in the twist @xmath0 correlator is related to causality property and compared with the prescriptions for exclusive hard processes. as a result we get the extra contributions, which naively do not have an imaginary phase.   the single spin asymmetry for the drell - yan process is accordingly enhanced by the factor of two.
hierarchic properties of chaotic scattering in a model of satellite encounters, studied first by petit and hnon, are examined by decomposing the dwell time function and comparing scattering trajectories.   the analysis reveals an ( approximate ) ternary organization in the chaotic set of bounded orbits and the presence of a stable island.   the results can open the way for a calculation of global quantities characterizing the scattering process by using tools of the thermodynamic formalism.
we present preliminary diameters and albedos for 13511 mbas that were observed during the 3-band cryo phase of the wise survey ( after the outer cryogen tank was exhausted ) and as part of the neowise post - cryo survey ( after the inner cryogen tank was exhausted ). with a reduced or complete loss of sensitivity in the two long wavelength channels of wise,   the uncertainty in our fitted diameters and albedos is increased to @xmath0 for diameter and @xmath1 for albedo.   diameter fits using only the @xmath2 and @xmath3 m channels are shown to be dependent on the literature optical @xmath4 absolute magnitudes.   these data allow us to increase the number of size estimates for large mbas which have been identified as members of dynamical families.   we present thermal fits for @xmath5 asteroids previously identified as the parents of a dynamical family that were not observed during the fully cryogenic mission.
the heterodyne instrument for the far infrared ( hifi ) aboard the herschel space observatory has acquired high - resolution broadband molecular spectra of star - forming regions in a wavelength range that is mostly inaccessible from ground - based astronomical observatories.   these spectral surveys provide new insight into the chemical composition and physical properties of molecular clouds. in this manuscript  , we present initial results from the hifi spectral survey of the sagittarius b2(n ) molecular cloud, which contains spectral features assigned to at least 40 different molecules in a range of physical environments. while extensive line blending   is observed due to the chemical complexity of this region, reliable molecular line identifications can be made, down to the noise floor, due to the large number of transitions detected for each species in the 1.2 thz survey bandwidth.   this allows for the extraction of new weakly emitting species from the line forest.   these hifi surveys will be an invaluable archival resource for future investigations into interstellar chemistry.   millimeter - wave spectroscopy ; astrochemistry ; interstellar molecules ; methanol
by taking into account the local energy balance per unit volume between the viscous heating and the advective cooling plus the radiative cooling, we investigate the vertical structure of radiation pressure - supported accretion disks in spherical coordinates.   our solutions show that the photosphere of the disk is close to the polar axis and therefore the disk seems to be extremely thick.   however, the profile of density implies that most of the accreted matter exists in a moderate range around the equatorial plane.   we show that the well - known polytropic relation between the pressure and the density is unsuitable for describing the vertical structure of radiation pressure - supported disks.   more importantly, we find that the energy advection is significant even for slightly sub - eddington accretion disks.   we argue that the non - negligible advection may help to understand why the standard thin disk model is likely to be inaccurate above @xmath0 eddington luminosity, which was found by some works on the black hole spin measurement.   furthermore, the solutions satisfy the solberg - hiland conditions, which indicates the disk to be convectively stable.   in addition, we discuss the possible link between our disk model and ultraluminous x - ray sources.
light propagation in a bragg periodic structure containing thin films with metallic nanoparticles is studied.   plasmonic resonance frequency, bragg frequency, and light carrier frequency are assumed to be close.   exact solutions describing solitary gap - waves are found, and a light arrest phenomenon due to nonlinearity of plasmonic oscillations is studied.
we first review previous work on anisotropic flow at the ags and sps.   then the physics related to flow is discussed as well as the interaction of flow with other non - flow measurements. from 40k rqmd and 100k hijing events predictions for anisotropic flow at rhic are presented. using the star detector acceptance, estimates for the resolution obtainable with star are shown.   we conclude that it should be possible to obtain good measurements for elliptic flow with either the star main tpc or forward tpcs.   anisotropic flow should be easily one of the first results from star.
we consider the effect of the ( heavy ) fundamental quarks on the low energy effective lagrangian description of nonabelian gauge theories in 2 + 1 dimensions.   we show that in the presence of the fundamental charges, the magnetic @xmath0 symmetry becomes local.   we construct the effective lagrangian representing this local symmetry in terms of magnetic vortex fields, and discuss its physical consequences.   we show that the finite energy states described by this lagrangian have distinct bag - like structure.   the point - like quarks are confined to the region of space where the value of the vortex field is much smaller than in the surrounding vacuum.
the impact of a sessile droplet with a moving meniscus, as encountered in processes such as dip - coating, generically leads to the entrapment of small air bubbles. here   we experimentally study this process of bubble formation by looking through the liquid using high - speed imaging.   our central finding is that the size of the entrapped bubble crucially depends on the location where coalescence between the drop and the moving meniscus is initiated : ( i ) at a finite height above the substrate, or ( ii ) exactly at the contact line. in the first case  , we typically find bubble sizes of the order of a few microns, independent of the size and speed of the impacting drop.   by contrast, the bubbles that are formed when coalescence starts at the contact line become increasingly large, as the size or the velocity of the impacting drop is increased.   we show how these observations can be explained from a balance between the lubrication pressure in the air layer and the capillary pressure of the drop.
the minimum - cost flow ( mcf ) problem is a fundamental optimization problem with many applications and seems to be well understood. over the last half century   many algorithms have been developed to solve the mcf problem and these algorithms have varying worst - case bounds on their running time.   however, these worst - case bounds are not always a good indication of the algorithms performance in practice. the network simplex ( ns )   algorithm needs an exponential number of iterations for some instances, but it is considered the best algorithm in practice and performs best in experimental studies. on the other hand,   the minimum - mean cycle canceling ( mmcc ) algorithm is strongly polynomial, but performs badly in experimental studies.    to explain these differences in performance in practice we apply the framework of smoothed analysis.   we show an upper bound of @xmath0 for the number of iterations of the mmcc algorithm. here   @xmath1 is the number of nodes, @xmath2 is the number of edges, and @xmath3 is a parameter limiting the degree to which the edge costs are perturbed.   we also show a lower bound of @xmath4 for the number of iterations of the mmcc algorithm, which can be strengthened to @xmath5 when @xmath6. for the number of iterations of the ns algorithm   we show a smoothed lower bound of @xmath7.
we study the distribution of the time - integrated current in an exactly - solvable toy model of heat conduction, both analytically and numerically.   the simplicity of the model allows us to derive the full current large deviation function and the system statistics during a large deviation event. in this way   we unveil a relation between system statistics at the end of a large deviation event and for intermediate times.   midtime statistics is independent of the sign of the current, a reflection of the time - reversal symmetry of microscopic dynamics, while endtime statistics do depend on the current sign, and also on its microscopic definition.   we compare our exact results with simulations based on the direct evaluation of large deviation functions, analyzing the finite - size corrections of this simulation method and deriving detailed bounds for its applicability.   we also show how the gallavotti - cohen fluctuation theorem can be used to determine the range of validity of simulation results.
we revisit the problem of phantom behaviour of effective dark energy in scalar - tensor gravity.   the main focus is on the properties of the functions defining the model.   we find that models with the present phantom behavior can be made consistent with all constraints, but one of these functions must have rather contrived shape, and the initial data must be strongly fine - tuned.   also, the phantom stage must have begun fairly recently, at @xmath0.   all this disfavors the effective phantom behaviour in the scalar - tensor gravity.
classification is an important task in many fields including biomedical research and machine learning.   traditionally, a classification rule is constructed based a bunch of labeled data. recently, due to technological innovation and automatic data collection schemes, we easily encounter with data sets containing large amounts of unlabeled samples. because to label each of them   is usually costly and inefficient, how to utilize these unlabeled data in a classifier construction process becomes an important problem. in machine learning literature,   active learning or semi - supervised learning are popular concepts discussed under this situation, where classification algorithms recruit new unlabeled subjects sequentially based on the information learned from previous stages of its learning process, and these new subjects are then labeled and included as new training samples. from a statistical aspect, these methods can be recognized as a hybrid of the sequential design and stochastic approximation procedure. in this paper, we study sequential learning procedures for building efficient and effective classifiers, where only the selected subjects are labeled and included in its learning stage.   the proposed algorithm combines the ideas of bayesian sequential optimal design and uncertainty sampling.   computational issues of the algorithm are discussed.   numerical results using both synthesized data and real examples are reported.   active learning, uncertainty sampling, sequential experimental design, d - optimal design, bayes rule
we have searched the northern sky for pulsars at the low radio frequency of 81.5mhz, using the 3.6-hectare array at cambridge, england.   the survey covered most of the sky north of declination @xmath0 and provided sensitivities of order 200mjy for pulsars not too close to the galactic plane.   a total of 20 pulsars were detected, all of them previously known.   the effective post - detection sampling rate was 1.3khz, and the sensitivity to low - dispersion millisecond pulsars was sufficient to allow the detection of objects similar to psr j0437@xmath14715 ( period 5.7ms, dispersion measure 2.6@xmath2pc, mean flux density @xmath3jy ).   no such pulsars were found.
energy spectra, electron densities, pair correlation functions and heat capacity of a quantum - dot lithium in zero external magnetic field ( a system of three interacting two - dimensional electrons in a parabolic confinement potential ) are studied using the exact diagonalization approach.   a particular attention is given to a fermi - liquid  wigner - solid transition in the ground state of the dot, induced by the intra - dot coulomb interaction.
we analyze the efficiency of different methods for the calculation of reaction rates in the case of a simple 2d analytical benchmark system.   two classes of methods are considered : the first are based on the free energy calculation along a reaction coordinate and the calculation of the transmission coefficient, the second on the sampling of dynamical pathways.   we give scaling rules for how this efficiency depends on barrier height and width, and we hand out simple optimization rules for the method - specific parameters.   we show that the path sampling methods, using the transition interface sampling technique, become exceedingly more efficient than the others when the reaction coordinate is not the optimal one.
the dynamical model developed in [ phys.   rev.   c * 54 *, 2660 ( 1996 ) ] has been applied to investigate the pion electroproduction reactions on the nucleon.   it is found that the model can describe to a very large extent the recent data of @xmath0 reaction from jefferson laboratory and mit - bates.   the extracted magnetic dipole(m1 ), electric dipole(e2 ), and coulomb(c2 ) strengths of the @xmath1 transition are presented.   it is found that the c2/m1 ratio drops significantly with q@xmath2 and reaches about -13@xmath3 at q@xmath2=4 ( gev / c)@xmath2, while the e2/m1 ratio remains close to the value @xmath4 at the @xmath5 photon point.   the determined m1 transition form factor drops faster than the usual dipole form factor of the proton.   we also find that the non - resonant interactions can dress the @xmath1 vertex to enhance strongly its strength at low @xmath6, but much less at high @xmath6.   predictions are presented for future experimental tests.   possible developments of the model are discussed.
motivated by recent experiments on rotating bose - einstein condensates, we investigate a rotating, polarized fermi gas trapped in an anharmonic potential. we apply a semiclassical expansion of the density of states in order to determine how the thermodynamic properties depend on the rotation frequency.   the accuracy of the semiclassical approximation is tested and shown to be sufficient for describing typical experiments. at zero temperature,   rotating the gas above a given frequency @xmath0 leads to a ` donut'-shaped cloud which is analogous to the hole found in two - dimensional bose - einstein condensates.   the free expansion of the gas after suddenly turning off the trap is considered and characterized by the time and rotation frequency dependence of the aspect ratio.   temperature effects are also taken into account and both low- and high - temperature expansions are presented for the relevant thermodynamical quantities. in the high - temperature regime a virial theorem approach is used to study the delicate interplay between rotation and anharmonicity.
a gravitating global k - monopole produces a tiny gravitational field outside the core in addition to a solid angular deficit in the k - field theory. as a new feature  , the gravitational field can be attractive or repulsive depending on the non - canonical kinetic term.
theories of stellar orbit diffusion in disk galaxies predict different rates of increase of the velocity dispersions parallel and perpendicular to the disk plane, and it is therefore of interest to measure the different velocity dispersion components in galactic disks of different types. we show that it is possible to extract the three components of the velocity ellipsoid in an intermediate - inclination disk galaxy from measured line - of - sight velocity dispersions on the major and minor axes. on applying the method to observations of the sb galaxy ngc 488  , we find evidence for a higher ratio of vertical to radial dispersion in ngc 488 than in the solar neighbourhood of the milky way ( the only other place where this quantity has ever been measured ).   the difference is qualitatively consistent with the notion that spiral structure has been relatively less important in the dynamical evolution of the disk of ngc 488 than molecular clouds.   galaxies : fundamental parameters  galaxies : individual : ngc488  galaxies : kinematics and dynamics.
a unit disk graph is the intersection graph of @xmath0 congruent disks in the plane. dominating sets in unit disk graphs   are widely studied due to their applicability in wireless ad - hoc networks. because the minimum dominating set problem for unit disk graphs is * np*-hard,   numerous approximation algorithms have been proposed in the literature, including some ptass. however, since the proposal of a linear - time @xmath1-approximation algorithm in 1995, the lack of efficient algorithms attaining better approximation factors has aroused attention.   we introduce an @xmath2 algorithm that takes the usual adjacency representation of the graph as input and outputs a @xmath3-approximation.   this approximation factor is also attained by a second algorithm, which takes the geometric representation of the graph as input and runs in @xmath4 time regardless of the number of edges.   additionally, we propose a @xmath5-approximation which can be obtained in @xmath6 time given only the graph s adjacency representation.   it is noteworthy that the dominating sets obtained by our algorithms are also independent sets.   approximation algorithms ; dominating set ; unit disk graph.
a general theory is presented to describe optomechanical interactions of acoustic phonons, having extremely long lifetimes in superfluid @xmath0he, with optical photons in the medium placed in a suitable electromagnetic cavity.   the acoustic nonlinearity in the fluid motion is included to consider processes beyond the usual linear process involving absorption or emission of one phonon at a time.   we first apply our formulation to the simplest one - phonon process involving the usual resonant anti - stokes upconversion of an incident optical mode.   however, when the allowed optical cavity modes are such that there is no single - phonon mode in the superfluid which can give rise to a resonant allowed anti - stokes mode, we must consider the possibility of two - phonon upconversion.   for such a case, we show that the two - step two - phonon process could be dominant.   we present arguments for large two - step process and negligible single step two - phonon contribution.   the two - step process also shows interesting quantum interference among different transition pathways.
a recently developed scheme [ s. scheel, l. knll, and d.-   g.   welsch, phys.   rev.   a * 58 *, 700 ( 1998 ) ] for quantizing the macroscopic electromagnetic field in linear dispersive and absorbing dielectrics satisfying the kramers - kronig relations is used to derive the quantum local - field correction for the standard virtual - sphere - cavity model.   the electric and magnetic local - field operators are shown to be consistent with qed only if the polarization noise is fully taken into account.   it is shown that the polarization fluctuations in the local field can dramatically change the spontaneous decay rate, compared with the familiar result obtained from the classical local - field correction.   in particular, the spontaneous emission rate strongly depends on the radius of the local - field virtual cavity.
we study the infrared singularities associated to ultra - soft transverse gluons in the calculation of photon production by a quark - gluon plasma. despite the fact that the kln theorem works in this context and provides cancellations of infrared singularities, it does not prevent the production rate of low invariant mass dileptons to be sensitive to the magnetic mass of gluons and therefore the rate to be non perturbative.    1.   laboratoire de physique thorique lapth, + umr 5108 du cnrs, associe  luniversit de savoie, + bp110, f-74941, annecy le vieux cedex, france 2  .   brookhaven national laboratory, + physics department, nuclear theory, + upton, ny-11973, usa    lapth756/99, bnl - nt99/5
the rock - paper - scissors ( rps ) game is a widely used model system in game theory.   evolutionary game theory predicts the existence of persistent cycles in the evolutionary trajectories of the rps game, but experimental evidence has remained to be rather weak. in this work   we performed laboratory experiments on the rps game and analyzed the social - state evolutionary trajectories of twelve populations of @xmath0 players.   we found strong evidence supporting the existence of persistent cycles.   the mean cycling frequency was measured to be @xmath1 period per experimental round.   our experimental observations can be quantitatively explained by a simple non - equilibrium model, namely the discrete - time logit dynamical process with a noise parameter.   our work therefore favors the evolutionary game theory over the classical game theory for describing the dynamical behavior of the rps game.   rock - paper - scissors game ; cycle ; social state ; population dynamics ; evolutionary trajectory
the saffman - taylor viscous fingering problem is investigated for the displacement of a non - newtonian fluid by a newtonian one in a radial hele - shaw cell.   we execute a mode - coupling approach to the problem and examine the morphology of the fluid - fluid interface in the weak shear limit. a differential equation describing the early nonlinear evolution of the interface modes   is derived in detail.   owing to vorticity arising from our modified darcy s law, we introduce a vector potential for the velocity in contrast to the conventional scalar potential.   our analytical results address how mode - coupling dynamics relates to tip - splitting and side branching in both shear thinning and shear thickening cases.   the development of non - newtonian interfacial patterns in rectangular hele - shaw cells is also analyzed.
if the scalar tau @xmath0 is the next lightest supersymmetric particle and decays into a gravitino(@xmath1 ) being the lightest supersymmetric particle, it will have generally a very long lifetime. in this paper  , we investigate the possibility to study the decay of such a long lived scalar tau at the lhc.   if we can add to the present lhc experiments additional detectors which are able to stop the stau particles and measure the produced decay products, the decay characteristics can be studied precisely at the lhc.   we identify a maximum `` stopper detector '' that could be added in the cms cavern, and estimate the sensitivity to the lifetime of the stau and to the mass of gravitino with this detector.   the decay of the scalar tau may be significantly modified if the decay channel to the axino @xmath2 is open.   we study the possibility to distinguish such decays from decays into gravitinos by measuring the process @xmath3 using the stopper detector.
the full super - kamiokande - iii data - taking period, which ran from august of 2006 through august of 2008, yielded 298 live days worth of solar neutrino data with a lower total energy threshold of 4.5 mev. during this period we made many improvements to the experiment s hardware and software, with particular emphasis on its water purification system and monte carlo simulations. as a result of these efforts  , we have significantly reduced the low energy backgrounds as compared to earlier periods of detector operation, cut the systematic errors by nearly a factor of two, and achieved a 4.5 mev energy threshold for the solar neutrino analysis. in this presentation, i will present the preliminary sk - iii solar neutrino measurement results.
we provide a general mechanism to design online learning algorithms based on a minimax analysis within a drifting - games framework.   different online learning settings ( hedge, multi - armed bandit problems and online convex optimization ) are studied by converting into various kinds of drifting games. the original minimax analysis for drifting games   is then used and generalized by applying a series of relaxations, starting from choosing a convex surrogate of the 0 - 1 loss function. with different choices of surrogates,   we not only recover existing algorithms, but also propose new algorithms that are totally parameter - free and enjoy other useful properties.   moreover, our drifting - games framework naturally allows us to study high probability bounds without resorting to any concentration results, and also a generalized notion of regret that measures how good the algorithm is compared to all but the top small fraction of candidates.   finally, we translate our new hedge algorithm into a new adaptive boosting algorithm that is computationally faster as shown in experiments, since it ignores a large number of examples on each round.
we consider lattice gas diffusive dynamics with creation - annihilation in the bulk and maintained out of equilibrium by two reservoirs at the boundaries.   this stochastic particle system can be viewed as a toy model for granular gases where the energy is injected at the boundary and dissipated in the bulk.   the large deviation functional for the particle currents flowing through the system is computed and some physical consequences are discussed : the mechanism for local current fluctuations, dynamical phase transitions, the fluctuation - relation.
we present a novel approach for the optical manipulation of neutral atoms in annular light structures produced by the phenomenon of conical refraction occurring in biaxial optical crystals. for a beam focused to a plane behind the crystal,   the focal plane exhibits two concentric bright rings enclosing a ring of null intensity called the poggendorff ring.   we demonstrate both theoretically and experimentally that the poggendorff dark ring of conical refraction is confined in three dimensions by regions of higher intensity.   we derive the positions of the confining intensity maxima and minima and discuss the application of the poggendorff ring for trapping ultra - cold atoms using the repulsive dipole force of blue - detuned light.   we give analytical expressions for the trapping frequencies and potential depths along both the radial and the axial directions.   finally, we present realistic numerical simulations of the dynamics of a @xmath0rb bose - einstein condensate trapped inside the poggendorff ring which are in good agreement with corresponding experimental results.
a strong coupling between convection and pulsations is known to play a major role in the disappearance of unstable modes close to the red edge of the classical cepheid instability strip. as mean - field models of time - dependent convection rely on weakly - constrained parameters ( e.g. *???   * ), we tackle this problem by the means of 2-d direct numerical simulations ( dns ) of @xmath0-mechanism with convection.    using a linear stability analysis, we first determine the physical conditions favourable to the @xmath0-mechanism to occur inside a purely - radiative layer.   both the instability strips and the nonlinear saturation of unstable modes are then confirmed by the corresponding dns.   we next present the new simulations with convection, where a convective zone and the driving region overlap.   the coupling between the convective motions and acoustic modes is then addressed by using projections onto an acoustic subspace.
we propose an effective hamiltonian approach to investigate decoherence of a quantum system in a non - markovian reservoir, naturally imposing the complete positivity on the reduced dynamics of the system.   the formalism is based on the notion of an effective reservoir, _   i.e. _, certain collective degrees of freedom in the reservoir that are responsible for the decoherence. as examples for completely positive decoherence, we present three typical decoherence processes for a qubit such as dephasing, depolarizing, and amplitude - damping.   the effects of the non - markovian decoherence are compared to the markovian decoherence.   = 10000
neutrinos from far - away sources annihilating at the z resonance on relic neutrinos may give origin to the extreme - energy cosmic rays ( eecr ). if `` z - bursts '' are responsible for the eecr events, then we show that the non - observation of cosmic ray events at energies above 2 @xmath0 ev by the agasa collaboration implies a lower bound @xmath1  ev on the relic neutrino mass.   since this mass exceeds the mass - squared differences inferred from oscillation physics, the bound in fact applies to all three neutrino masses.   together with the upper bound provided by comparisons of the cmb anisotropy with large - scale structure, this bound leaves only a small interval for neutrino masses around 0.3 ev, if z - bursts are to explain the existing eecr events.
the gottesman - knill theorem allows for the efficient simulation of stabilizer - based quantum error - correction circuits.   errors in these circuits are commonly modeled as depolarizing channels by using monte carlo methods to insert pauli gates randomly throughout the circuit. although convenient, these channels are poor approximations of common, realistic channels like amplitude damping. here   we analyze a larger set of efficiently simulable error channels by allowing the random insertion of any one - qubit gate or measurement that can be efficiently simulated within the stabilizer formalism.   our new error channels are shown to be a viable method for accurately approximating real error channels.
we propose a detailed investigation of the schematic mode - coupling approach to experimental data, a method based on the use of simple mode - coupling equations to analyze the dynamics of supercooled liquids.   our aim here is to clarify different aspects of this approach that appeared so far uncontrolled or arbitrary, and to validate the results obtained from previous works. analyzing the theoretical foundations of the approach  , we first identify the parameters of the theory playing a key role and obtain simple requirements to be met by a schematic model for its use in this context.   then we compare the results obtained from the schematic analysis of a given set of experimental data with a variety of models and show that they are all perfectly consistent.   a number of potential biases in the method are identified and ruled out by the choice of appropriate models.   finally, reference spectra computed from the mode - coupling theory for a model simple liquid are analyzed along the same lines as experimental data, allowing us to show that, despite the strong simplification in the description of the dynamics it involves, the method is free from spurious artifacts and provides accurate estimates of important parameters of the theory.   the only exception is the exponent parameter, the evaluation of which is hindered, as for other methods, by corrections to the asymptotic laws of the theory present when the dynamics is known only in a limited time or frequency range.
circumstances are described in which symmetry breaking during the formation of our three - dimensional brane within a higher - dimensional space in the early universe excites mesoscopic classical radion or brane - displacement degrees of freedom and produces a detectable stochastic background of gravitational radiation.   the spectrum of the background is related to the unification energy scale and the the sizes and numbers of large extra dimensions.   it is shown that properties of the background observable by gravitational - wave observatories at frequencies @xmath0 hz to @xmath1 hz contain information about unification on energy scales from @xmath2 to @xmath3 tev, gravity propagating through extra - dimension sizes from 1 mm to @xmath4 mm, and the dynamical history and stabilization of from one to seven extra dimensions.
exciton - polariton condensates display a variety of intriguing pattern - forming behaviors, particularly when confined in potential traps.   it has previously been predicted that triangular lattices of vortices of the same sign will form spontaneously as the result of surface instabilities in a harmonic trap. however, natural disorder, deviation of the external potential from circular symmetry, or higher - order terms modifying the dynamical equations may all have detrimental effects and destabilize the circular trajectories of vortices. here   we address these issues, by characterizing the robustness of the vortex lattice against disorder and deformations of the trapping potential. since most experiments use time integrated measurements it would be hard to observe directly the rotating vortex lattices or distinguish them from vortex - free states.   we suggest how these difficulties can be overcome and present an experimentally viable interference - imaging scheme that would allow the detection of rotating vortex lattices.
radiation pressure dominated accretion discs around compact objects may have turbulent velocities that greatly exceed the electron thermal velocities within the disc.   bulk comptonization by the turbulence may therefore dominate over thermal comptonization in determining the emergent spectrum.   bulk comptonization by divergenceless turbulence is due to radiation viscous dissipation only.   it can be treated as thermal comptonization by solving the kompaneets equation with an equivalent  wave " temperature, which is a weighted sum over the power present at each scale in the turbulent cascade.   bulk comptonization by turbulence with non - zero divergence is due to both pressure work and radiation viscous dissipation.   pressure work has negligible effect on photon spectra in the limit of optically thin turbulence, and in this limit radiation viscous dissipation alone can be treated as thermal comptonization with a temperature equivalent to the full turbulent power. in the limit of extremely optically thick turbulence, radiation viscous dissipation is suppressed, and the evolution of local photon spectra can be understood in terms of compression and expansion of the strongly coupled photon and gas fluids.   we discuss the consequences of these effects for self - consistently resolving and interpreting turbulent comptonization in spectral calculations in radiation mhd simulations of high luminosity accretion flows.       accretion, accretion discs  radiation mechanisms : non - thermal  turbulence  galaxies : active  x - rays : binaries.
the observations of jet breaks in the afterglows of short gamma - ray bursts ( sgrbs ) indicate that the jet has a small opening angle of @xmath0.   the collimation mechanism of the jet is a longstanding theoretical problem.   we numerically analyze the jet propagation in the material ejected by double neutron star merger, and demonstrate that if the ejecta mass is @xmath1, the jet is well confined by the cocoon and emerges from the ejecta with the required collimation angle.   our results also suggest that there are some populations of choked ( failed ) sgrbs or low - luminous new types of event. by constructing a model for sgrb 130603b, which is associated with the first kilonova / macronova candidate  , we infer that the equation - of - state of neutron stars would be soft enough to provide sufficient ejecta to collimate the jet, if this event was associated with a double neutron star merger.
we present a general and powerful, yet simple, class of weighted networks embedded in hidden metric spaces.   this class of weighted networks allows an explicit prescription of the joint degree and strength distributions, and the control of the weight distribution and the local disparity of weights by tuning their coupling with the underlying metric space.   we present an approach to estimate whether an underlying metric space is needed to explain the weighted features of real networks and show that the model generates networks that reproduce these properties advantageously.   the results suggest that the nontrivial weighted structure of real networks could be explained by the coupling between the weights and an underlying metric space, and open the way to the embedding of real weighted networks and to unveiling their natural hidden geometry.
we derive a renormalization group formalism for the randall - sundrum scenario, where the renormalization scale is set by a floating compactification radius.   while inspired by the ads / cft conjecture, our results are derived concretely within higher - dimensional effective field theory. matching theories with different   radii leads to running hidden brane couplings.   the hidden brane lagrangian consists of four - dimensional local operators constructed from the induced value of the bulk fields on the brane.   we find hidden lagrangians which are non - trivial fixed points of the rg flow.   calculations in rs1 can be greatly simplified by `` running down '' the effective theory to a small radius.   we demonstrate these simplifications by studying the goldberger - wise stabilization mechanism. in this paper  , we focus on the classical and tree - level quantum field theory of bulk scalar fields, which demonstrates the essential features of the rg in the simplest context.
a detailed study of orbital and radial excited states in @xmath0 and @xmath1 systems is performed.   the chiral quark model provides the framework for the calculation of pseudoscalar meson ( @xmath2 ) hadronic transitions among heavy - light excited and ground states. to calculate the excited states masses and wavefunctions  , we must resort to a relativistic quark model.   our model includes the leading order corrections in @xmath3 ( e.g. mixing ). numerical results for masses and light hadronic transition rates are compared to existing experimental data.   the effective coupling of the chiral quark model can be determined by comparing with independent results from lattice simulations ( @xmath4 ) or fitting to known widths ( @xmath5 ).   fermilab pub-01/033-t + hep - ph/0104208 + april  2001 +     +   +
we present results from gmrt hi 21 cm line observations of the interacting galaxy pair arp 181 ( ngc3212 and ngc3215 ) at z = 0.032.   we find almost all of the detected hi ( 90% ) displaced well beyond the optical disks of the pair with the highest density hi located @xmath070 kpc west of the pair.   an hi bridge between the optical pair and the bulk of the hi strong evidence that hi to the west of the pair has two approximately intensity peaks.   the hi intensity maximum furthest to the west coincides with a small companion sdss j102726.32 + 794911.9 which shows enhanced mid   infrared ( spitzer ), uv ( galex ) and h@xmath1 emission indicating intense star forming activity.   the hi intensity maximum close to the arp 181 pair, coincides with a diffuse optical cloud detected in uv ( galex ) at the end of the stellar and hi tidal tails originating at ngc3212, previously proposed a tidal dwarf galaxy in formation.   future sensitive hi surveys by telescopes like askap should prove to be powerful tools for identifying tidal dwarfs at moderate to large redshifts to explore in detail the evolution of dwarf galaxies in the universe.       galaxies : spiral - galaxies : interactions - galaxies : kinematics and dynamics - galaxies : individual : arp 181 - radio lines : galaxies - radio continuum : galaxies
we discuss electron spin resonance ( esr ) shifts in spin-1 heisenberg antiferromagnetic chains with a weak single - ion anisotropy, based on several effective field theories : the o(3 ) nonlinear sigma model ( nlsm ) in the haldane phase, free fermion theories around the lower and the upper critical fields. in the o(3 ) nlsm, the single - ion anisotropy corresponds to a composite operator which creates two magnons at the same time and position.   therefore, even inside a parameter range where free magnon approximation is valid for thermodynamics, we have to take interactions among magnons into account in order to include the single - ion anisotropy as a perturbation.   although the o(3 ) nlsm is only valid in the haldane phase, an appropriate translation of faddeev - zamolodchikov operators of the o(3 ) nlsm to fermion operators enables one to treat esr shifts near the lower critical field in a similar manner to discussions in the haldane phase.   our theory gives quantitative agreements with a numerical evaluation using quantum monte carlo simulation, and also with recent esr experimental results on a spin-1 chain compounds ndmap.
the geological systems such as petroleum reservoirs is investigated by the entropy introduced by tsallis and multiplicative hierarchical cascade model. when non - gaussianity appears, it is sign of uncertainty and phase transition, which could be sign of existence of petroleum reservoirs.   two important parameters which describe a system at any scale are determined ; the non - gaussian degree, @xmath0, announced in entropy and the intermittency, @xmath1, which explains a critical behavior in the system.   there exist some petrophysical indicators in order to characterize a reservoir, but there is vacancy to measure scaling information contain in comparison with together, yet. in this article  , we compare the non - gaussianity in three selected indicators in various scales.   the quantities investigated in this article includes gamma emission ( gr ), sonic transient time ( dt ) and neutron porosity ( nphi ).   it is observed that gr has a fat tailed pdf at all scales which is a sign of phase transition in the system which indicates high @xmath0 and @xmath1.   this results in the availability of valuable information about this quantity.   nphi displays a scale dependence of pdf which converges to a gaussian at large scales.   this is a sign of a separated and uncorrelated porosity at large scales. for the dt series, small @xmath1 and @xmath0 at all scales   are a hallmark of local correlations in this quantity.   keywords : tsallis entropy, non - gaussian degree, intermittency.
we present an x - ray timing analysis of the transient x - ray binary, using data obtained from the @xmath0 and @xmath1 observatories.   we have made 27 new mid eclipse time measurements from observations made during the two outbursts of the source.   these new measurements have been combined with the previously known values to study long term changes in orbital period of the binary system.   we have found that the mid - eclipse timing record of   is quite unusual.   the long term evolution of mid - eclipse times indicates an overall orbital period decay with a time scale of   6.5(7 ) @xmath2 10@xmath3 year. over and above this orbital period decay  , the o - c residual curve also shows a periodic residual on shorter timescales.   this sinusoidal variation has an amplitude of @xmath49 lt - sec and a period of @xmath4760 d. this is indicative of presence of a third body around the compact x - ray binary. the mass and orbital radius of the third body are estimated to lie in the range, 20.526.9 jupiter mass and 750 - 860 lt - sec, respectively.   if true, then it will be the most massive circumbinary planet and also the smallest period binary known to host a planet.       x - rays : binaries : eclipsing, stars : neutron, individual :, planet - star interaction
recently a fingering morphology, resembling the hydrodynamic saffman - taylor instability, was identified in the quasi - two - dimensional electrodeposition of copper.   we present here measurements of the dispersion relation of the growing front.   the instability is accompanied by gravity - driven convection rolls at the electrodes, which are examined using particle image velocimetry. while at the anode the theory presented by chazalviel et al. describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit.   in particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.
we present spectrophotometric imaging mid  ir observations of the reflection nebula ced201.   ced201 is a part of a molecular cloud illuminated by a b9.5v star moving through it at more than 12 km s@xmath0.   the spectra of ced201 give evidence for transformation of very small carbonaceous grains into the carriers of the aromatic infrared bands ( aibs ), due to the radiation field of the illuminating star and/or to shock waves created by its motion.   these very small grains emit mainly very broad bands and a continuum.   we suggest that they are present everywhere in the interstellar medium but can only be detected in the mid   ir under special circumstances such as those prevailing in this reflection nebula. the efficiency of energy conversion of stellar light into mid   infrared emission is 7.5%   for both the very small grains and the aib carriers, and the fraction of interstellar carbon locked in these emitters is approximately 15%.
are there two - player games in which a strategy pair can exist as a nash equilibrium only when the game is played quantum mechanically? to find an answer to this question, we study two - player games that are played in generalized einstein - podolsky - rosen setting. considering particular strategy pairs  , we identify sets of games for which the pair can exist as a nash equilibrium when bell s inequality is violated.   we thus identify games and players strategies for which the nash inequality becomes equivalent to bell s inequality. as the violation of bell s inequality   is regarded as being quantum in nature, this paper thus addresses the earliest criticisms of quantum games that questioned if they were truly quantum.
the lambert @xmath0 function and its possible applications in physics are presented. the actual numerical implementation in c++ consists of halley s and fritsch s iterations with initial approximations based on branch - point expansion, asymptotic series, rational fits, and continued - logarithm recursion.   lambert w function, computational physics, numerical methods and algorithms, c++    @xmath1 +
we search for stars with proper motions in a set of deep subaru images, covering about 0.48 square degrees to a depth of @xmath0, taken over a span of five and a half years.   we follow the methods described in @xcite to reduce and analyze this dataset.   we present a sample of 69 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. based on photometry and motions alone  , we expect that 14 of the candidates may be white dwarfs.   our candidate with the largest proper motion is surprisingly faint and likely to prove interesting : its colors and motions suggest that it might be an m dwarf moving at over 500 km / sec or an l dwarf in the halo.
the pulsar wind model is updated by considering the effect of particle density and pulsar death.   it can describe both the short term and long term rotational evolution of pulsars consistently.   it is applied to model the rotational evolution of the crab pulsar.   the pulsar is spun down by a combination of magnetic dipole radiation and particle wind.   the parameters of the crab pulsar, including magnetic field, inclination angle, and particle density are calculated.   the primary particle density in acceleration region is about @xmath0 times the goldreich - julian charge density.   the lower braking index between glitches is due to a larger outflowing particle density  . this may be glitch induced magnetospheric activities in normal pulsars.   evolution of braking index and the crab pulsar in @xmath1 diagram are calculated.   the crab pulsar will evolve from magnetic dipole radiation dominated case towards particle wind dominated case. considering the effect of pulsar `` death '', the crab pulsar ( and other normal pulsars ) will not evolve to the cluster of magnetars but downwards to the death valley.   different acceleration models are also considered.   applications to other sources are also discussed, including pulsars with braking index measured, and the magnetar population.       pulsars : general  pulsars : individal ( psr b0531 + 21 )  stars : magnetar  stars : neutron
diffuse 511 kev line emission, from the annihilation of cold positrons, has been observed in the direction of the galactic centre for more than 30 years.   the latest high - resolution maps of this emission produced by the spi instrument on integral suggest at least one component of the emission is spatially coincident with the distribution of @xmath070 luminous, low - mass x - ray binaries detected in the soft gamma - ray band. the x - ray band,   however, is generally a more sensitive probe of x - ray binary populations.   recent x - ray surveys of the galactic centre have discovered a much larger population ( @xmath14000 ) of faint, hard x - ray point sources.   we investigate the possibility that the positrons observed in the direction of the galactic centre originate in pair - dominated jets generated by this population of _ fainter _ accretion - powered x - ray binaries.   we also consider briefly whether such sources could account for unexplained diffuse emission associated with the galactic centre in the microwave ( the wmap ` haze') and at other wavelengths.   finally, we point out several unresolved problems in associating galactic centre 511 kev emission with the brightest x - ray binaries.   _ dark matter ; compact objects ; x - ray binaries ; galactic centre ; accretion, accretion physics ; jets _
the sort transform ( st ) is a modification of the burrows - wheeler transform ( bwt ).   both transformations map an arbitrary word of length @xmath0 to a pair consisting of a word of length @xmath0 and an index between @xmath1 and @xmath0.   the bwt sorts all rotation conjugates of the input word, whereas the st of order @xmath2 only uses the first @xmath2 letters for sorting all such conjugates.   if two conjugates start with the same prefix of length @xmath2, then the indices of the rotations are used for tie - breaking. both transforms output the sequence of the last letters of the sorted list and the index of the input within the sorted list. in this paper, we discuss a bijective variant of the bwt ( due to scott ), proving its correctness and relations to other results due to gessel and reutenauer ( 1993 ) and crochemore, dsarmnien, and perrin ( 2005 ).   further, we present a novel bijective variant of the st.
online reviews are often our first port of call when considering products and purchases online.   when evaluating a potential purchase, we may have a specific query in mind, e.g. ` will this baby seat fit in the overhead compartment of a 747?'or ` will i like this album if i liked taylor swift s _ 1989 _? '. to answer such questions   we must either wade through huge volumes of consumer reviews hoping to find one that is relevant, or otherwise pose our question directly to the community via a q / a system.    in this paper   we hope to fuse these two paradigms : given a large volume of previously answered queries about products, we hope to automatically learn whether a review of a product is relevant to a given query.   we formulate this as a machine learning problem using a mixture - of - experts - type framework  here   each review is an ` expert'that gets to vote on the response to a particular query ; simultaneously we learn a relevance function such that ` relevant'reviews are those that vote correctly. at test time   this learned relevance function allows us to surface reviews that are relevant to new queries on - demand.   we evaluate our system, _ moqa _, on a novel corpus of 1.4 million questions ( and answers ) and 13 million reviews.   we show quantitatively that it is effective at addressing both binary and open - ended queries, and qualitatively that it surfaces reviews that human evaluators consider to be relevant.
the june  2004 version of our compilation of measured redshifts for clusters in the abell - aco catalogue lists redshifts for 3715 clusters / subclusters in 3033 distinct ( 2396 a- and 637 s- ) clusters, 67% of these with @xmath0 galaxies measured.   we provide velocity dispersions ( @xmath1 ) for 1875 ( sub)clusters towards 1353 unique aco clusters.   the median @xmath1 is 650kms@xmath2 for a-(sub)clusters and 575kms@xmath2 for s-(sub)clusters, and @xmath1 clearly increases with both, @xmath3 and richness, and also, somewhat surprising, with later bautz - morgan type of the clusters.   we show examples of supercluster properties based on these data.
we consider bosonic atoms in an optical lattice at integer filling, tuned to the superfluid - mott insulator critical point, and coupled to a single, mobile impurity atom of a different species.   this setup is inspired by current experiments with quantum gas microscopes, which enable tracking of the impurity motion.   we describe the evolution of the impurity motion from quantum wave packet spread at short times, to brownian diffusion at long times.   this dynamics is controlled by the interplay between dangerously irrelevant perturbations at the strongly - interacting field theory describing the superfluid - insulator transition in two spatial dimensions.
the separability of the continuous - variable epr state can be tested with hanbury - brown and twiss type interference.   the second - order visibility of such interference can provide an experimental test of entanglement.   it is shown that time - resolved interference leads to the hong, ou and mandel deep, that provides a signature of quantum non - separability for pure and mixed epr states.   a hanbury - brown and twiss type witness operator can be constructed to test the quantum nature of the epr entanglement.
a quantitative understanding of charge - symmetry breaking is an increasingly important ingredient for the extraction of the nucleon s strange vector form factors.   we review the theoretical understanding of the charge - symmetry - breaking form factors, both for single nucleons and for @xmath0.
we use bank - level balance sheet data from 2005 to 2010 to study interactions within the banking system of five emerging countries : argentina, brazil, mexico, south africa, and taiwan. for each country   we construct a financial network based on the leverage ratio dependence between each pair of banks, and find results that are comparable across countries.   banks present a variety of leverage ratio behaviors.   this leverage diversity produces financial networks that exhibit a modular structure characterized by one large bank community, some small ones and isolated banks.   there exist compact structures that have synchronized dynamics.   many groups of banks merge together creating a financial network topology that converges to a unique big cluster at a relatively low leverage dependence level.   finally, we propose a model that includes corporate and interbank loans for studying the banking system.   this model generates networks similar to the empirical ones.   moreover, we find that faster - growing banks tend to be more highly interconnected between them, and this is also observed in empirical data.    # 1#1 :    biblabel#1
we set the first limits on the ultra - high energy ( uhe ) neutrino fluence at energies greater than @xmath0  gev from gamma - ray bursts ( grbs ) based on data from the second flight of the antarctic impulsive transient antenna ( anita ). during the 31 day flight of anita - ii,   26 grbs were recorded by swift or fermi. of these  , we analyzed the 12 grbs which occurred during quiet periods when the payload was away from anthropogenic activity. in a blind analysis, we observe 0 events on a total background of 0.0044 events in the combined prompt window for all 12 low - background bursts.   we also observe 0 events from the remaining 14 bursts.   we place a 90% confidence level limit on the @xmath1 prompt neutrino fluence between 10@xmath2  gev@xmath3e@xmath310@xmath4  gev of @xmath5=2.5@xmath6  gev@xmath7/@xmath8 from grb090107a.   this is the first reported limit on the uhe neutrino fluence from grbs above 10@xmath9  gev, and the strongest limit above 10@xmath2  gev.
several variants of the recently proposed density matrix embedding theory ( dmet ) [ g. knizia and g. k - l.   chan, _ phys.   rev.   lett. _ * 109 *, 186404 ( 2012 ) ] are formulated and tested.   we show that spin symmetry breaking of the lattice mean - field allows precise control of the lattice and fragment filling while providing very good agreement between predicted properties and exact results.   we present a rigorous proof that at convergence this method is guaranteed to preserve lattice and fragment filling.   differences arising from fitting the fragment one - particle density matrix alone versus fitting fragment plus bath are scrutinized.   we argue that it is important to restrict the density matrix fitting to solely the fragment.   furthermore, in the proposed broken symmetry formalism, it is possible to substantially simplify the embedding procedure without sacrificing its accuracy by resorting to _ density _ instead of _ density matrix _ fitting.   this simplified density embedding theory ( det ) greatly improves the convergence properties of the algorithm.
we develop a theory for light - induced superconductivity in underdoped cuprates in which the competing bond - density wave order is suppressed by driving phonons with light.   close to a bond - density wave instability in a system with a small fermi surface, such as a fractionalized fermi liquid, we show that the coupling of electrons to phonons is strongly enhanced at the bond - density wave ordering wavevectors, leading to a strong softening of phonons at these wavevectors. for a model of classical phonons with anharmonic couplings,   we show that the combination of strong softening and driving can lead to large phonon oscillations.   when coupled to a phenomenological model describing the competition between bond - density wave order and superconductivity, these phonon oscillations melt bond - density wave order, thereby enhancing pairing correlations.
social media, regarded as two - layer networks consisting of users and items, turn out to be the most important channels for access to massive information in the era of web 2.0.   the dynamics of human activity and item popularity is a crucial issue in social media networks. in this paper, by analyzing the growth of user activity and item popularity in four empirical social media networks, i.e., amazon, flickr, delicious and wikipedia, it is found that cross links between users and items are more likely to be created by active users and to be acquired by popular items, where user activity and item popularity are measured by the number of cross links associated with users and items.   this indicates that users generally trace popular items, overall.   however, it is found that the inactive users more severely trace popular items than the active users. inspired by empirical analysis, we propose an evolving model for such networks, in which the evolution is driven only by two - step random walk.   numerical experiments verified that the model can qualitatively reproduce the distributions of user activity and item popularity observed in empirical networks.   these results might shed light on the understandings of micro dynamics of activity and popularity in social media networks.
in a two - flavor color superconductor, the @xmath0 gauge symmetry is spontaneously broken by diquark condensation.   the nambu - goldstone excitations of the diquark condensate mix with the gluons associated with the broken generators of the original gauge group.   it is shown how one can decouple these modes with a particular choice of t  hooft gauge.   we then explicitly compute the spectral density for transverse and longitudinal gluons of adjoint color 8.   the nambu - goldstone excitations give rise to a singularity in the real part of the longitudinal gluon self - energy.   this leads to a vanishing gluon spectral density for energies and momenta located on the dispersion branch of the nambu - goldstone excitations.
in this paper, we present a novel approach to model the fluid / solid interaction forces in a direct solver of the navier - stokes equations based on the volume of fluid interface tracking method. the key ingredient of the model is the explicit inclusion of the fluid / solid interaction forces into the governing equations. we show that the interaction forces lead to a partial wetting condition and in particular to a natural definition of the equilibrium contact angle.   we present two numerical methods to discretize the interaction forces that enter the model ; these two approaches differ in complexity and convergence. to validate the computational framework  , we consider the application of these models to simulate two - dimensional drops at equilibrium, as well as drop spreading.   we demonstrate that the model, by including the underlying physics, captures contact line dynamics for arbitrary contact angles.   more generally, the approach permits novel means to study contact lines, as well as a diverse range of phenomena that previously could not be addressed in direct simulations.
complex networks have been shown to be robust against random structural perturbations, but vulnerable against targeted attacks.   robustness analysis usually simulates the removal of individual or sets of nodes, followed by the assessment of the inflicted damage. for complex metabolic networks, it has been suggested that evolutionary pressure may favor robustness against reaction removal.   however, the removal of a reaction and its impact on the network may as well be interpreted as selective regulation of pathway activities, suggesting a tradeoff between the efficiency of regulation and vulnerability. here, we employ a cascading failure algorithm to simulate the removal of single and pairs of reactions from the metabolic networks of two organisms, and estimate the significance of the results using two different null models : degree preserving and mass - balanced randomization.   our analysis suggests that evolutionary pressure promotes larger cascades of non - viable reactions, and thus favors the ability of efficient metabolic regulation at the expense of robustness.
gemini north adaptive optics imaging spectroscopy is presented for the galactic ultra  compact ( ) region k350a.   data were obtained in the @xmath0band using the near  infrared integral field spectrograph ( nifs ) behind the facility adaptive optics module altair in natural guide star mode.   the nifs data cube reveals a complex spatial morphology across the 0.1 pc scale of the 3@xmath1  region.   comparison of the nebular emission to cloudy ionization models shows that the central source must have an effective temperature between about 37000 k and 45000 k with preferred values near 40000 k. evidence is presented for sharp density variations in the nebula which are interpreted as a clearing of material nearest the central source.   high excitation lines of  and  show that the ionization of the nebula clearly changes with distance from the central source.   a double lobed kinematic signature ( @xmath2 25 ) is evident in the br@xmath3 line map which may be related to the larger scale ionized flow detailed in earlier investigations.   this signature and the large scale flow are not co - alighned, but they may still be related. though clearly resolved from the nebula,   the central source itself remains buried, and the nifs spectrum shows no evidence of photospheric lines.
topological insulators ( tis ) are a new quantum state of matter discovered recently, which are characterized by unconventional bulk topological invariants.   proposals for practical applications of the tis are mostly based upon their metallic surface or edge states. here,   we report the theoretical discovery of a bulk quantum pumping effect in a two - dimensional ti electrically modulated in adiabatic cycles. in each cycle  , an amount of spin proportional to the sample width can be pumped into a nonmagnetic electrode, which is attributed to nonzero spin chern numbers @xmath0. moreover, by using a half - metallic electrode, universal quantized charge pumping conductivities @xmath1 can be measured.   this discovery paves the way for direct investigation of the robust topological properties of the tis.
precision cosmology studies based on wide - field surveys of galaxy clusters benefit from constraints on intrinsic scatter in mass - observable relationships. in principle, two - parameter models combining direct measurements of galaxy cluster structural variation with mass proxies such as x - ray luminosity and temperature can be used to constrain scatter in the relationship between the mass proxy and the cluster s halo mass and to measure the redshift evolution of that scatter.   one candidate for quantifying cluster substructure is the icm temperature inhomogeneity inferred from x - ray spectral properties, an example of which is, the ratio of hardband to broadband spectral - fit temperatures. in this paper   we test the effectiveness of  as an indicator of scatter in the mass - temperature relation using 118 galaxy clusters simulated with radiative cooling and feedback.   we find that, while  is correlated with clusters departures @xmath0 from the mean  relation, the effect is modest.   2x - mas
the injection of electrons in the bulk of carbon nanotube which is connected to ideal fermi liquid leads is considered.   while the presence of the leads gives a cancellation of the noise cross - correlations, the auto - correlation noise has a fano factor which deviates strongly from the schottky behavior at voltages where finite size effects are expected.   indeed, as the voltage is increased from zero, the noise is first super - poissonian, then sub - poissonian, and eventually it reaches the schottky limit.   these finite size effects are also tested using a diagnosis of photo - assisted transport, where a small ac modulation is superposed to the dc bias voltage between the injection tip and the nanotube.   when finite size effects are at play, we obtain a stepwise behavior for the noise derivative, as expected for normal metal systems, whereas in the absence of finite size effects, due to the presence of coulomb interactions, a smoothed staircase is observed.   the present work shows that it is possible to explore finite size effects in nanotube transport via a zero - frequency noise measurement.
we report on a long x - ray observation of the slow - rotating binary pulsar gx1 + 4.   _ bepposax _ observed, in the 0.1200kev energy range, an event in which the source flux dropped for almost a day, and then recovered. during this event   only the high - energy emission was found to be pulsed and the pulsations were shifted in phase of @xmath0.   the spectrum during the event was well fitted by a compton - reflection model.   a broad iron line at @xmath1kev was present outside of the event, where instead two narrow emission lines at @xmath2kev and @xmath3kev were detected.   the pulse profile was highly variable as a function of both energy and time.   we interpret this low - flux event as an occultation of the direct x - ray emission, due to the increase of a torus - like accretion disk ; we then discuss similarities between this source and the recently discovered highly absorbed _ integral _ sources.   ,   ,   ,   ,   ,    and    neutron star, pulsar, binary system, gx1 + 4, compton reflection
we analyze the entanglement between two modes of a free dirac field as seen by two relatively accelerated parties.   the entanglement is degraded by the unruh effect and asymptotically reaches a non - vanishing minimum value in the infinite acceleration limit.   this means that the state always remains entangled to a degree and can be used in quantum information tasks, such as teleportation, between parties in relative uniform acceleration.   we analyze our results from the point of view afforded by the phenomenon of entanglement sharing and in terms of recent results in the area of multi - qubit complementarity.
we propose a computational procedure for creating a stable equilibrium triple junction ( tj ) with controlled grain misorientations.   we apply this procedure to construct a tj between a @xmath0 grain boundary ( gb ) and two general high - angle gbs in copper, and calculate the diffusion coefficients along the tj and the gbs using molecular dynamics with an embedded - atom potential.   the tj diffusion is only a factor of two faster than diffusion in the @xmath1 gb but significantly faster than diffusion in the general gbs.   both the gbs and the tj studied here show a premelting behavior near the bulk melting point, where their diffusivities converge to the diffusivity of bulk liquid.   although our results are consistent with the common assumption that tj diffusion is generally faster than gb diffusion, the difference between the two diffusivities does not appear to be large enough to ensure a significant contribution of tjs to diffusional creep in polycrystals at high temperatures.
investigate baryogenesis via leptogenesis and generation of neutrino masses and mixings through the type i plus type iii seesaw plus an one - loop mechanism in the context of renormalizable adjoint @xmath0 theory.   one light neutrino remains massless, because the contributions from three heavy majorana fermions @xmath1, @xmath2 and @xmath3 to the neutrino mass matrix are not linearly independent.   however none of these heavy fermions is decoupled from the generation of neutrino masses.   this opens a new range in parameter space for successful leptogenesis, in particular, allows for inverted hierarchy of the neutrino masses.
electromagnetic energy loss of tau leptons is an important ingredient for eventual tau neutrino detection from high energy astrophysical sources.   proposals have been made to use mountains as neutrino converters, in which the emerging tau decays in an air shower.   we use a stochastic evaluation of both tau neutrino conversion to taus and of tau electromagnetic energy loss.   we examine the effects of the propagation for mono - energetic incident tau neutrinos as well as for several neutrino power - law spectra.   our main result is a parameterization of the tau electromagnetic energy loss parameter @xmath0.   we compare the results from the analytic expression for the tau flux using this @xmath0 with other parameterizations of @xmath0.
photonic quantum simulators are promising candidates for providing insight into other small- to medium - sized quantum systems.   the available photonic quantum technology is reaching the state where significant advantages arise for the quantum simulation of interesting questions in heisenberg spin systems. here   we experimentally simulate such spin systems with single photons and linear optics.   the effective heisenberg - type interactions among individual single photons are realized by quantum interference at the tunable direction coupler followed by the measurement process.   the effective interactions are characterized by comparing the entanglement dynamics using pairwise concurrence of a four - photon quantum system.   we further show that photonic quantum simulations of generalized heisenberg interactions on a four - site square lattice and a six - site checkerboard lattice are in reach of current technology.
we experimentally investigate the phenomenon of a quantum ratchet created by exposing a bose - einstein condensate to short pulses of a potential which is periodic in both space and time.   such a ratchet is manifested by a directed current of particles, even though there is an absence of a net bias force.   we confirm a recent theoretical prediction [ m. sadgrove and s. wimberger, new j. phys. *   11 *, 083027 ( 2009 ) ] that the current direction can be controlled by experimental parameters which leave the underlying symmetries of the system unchanged.   we demonstrate that this behavior can be understood using a single variable containing many of the experimental parameters and thus the ratchet current is describable using a single universal scaling law.
the galactic center region is expected to host the largest density of dark matter ( dm ) particles within the milky way.   then a relatively large gamma - ray signal would be expected from the possible dm particles annihilation ( or decay ).   we are searching for the dm gamma - ray signal from the galactic center, which is also rich in bright discrete gamma - ray sources.   furthermore intense diffuse gamma - ray emission due to cosmic - ray interactions with interstellar gas and radiation is detected from the same direction.    a preliminary analysis of the data, taken during the first 11 months of the fermi satellite operations, is reported.   the diffuse gamma - ray backgrounds and discrete sources, as we know them today, can account for the large majority of the detected gamma - ray emission from the galactic center.   nevertheless a residual emission is left, not accounted for by the above models.   an improved model of the galactic diffuse emission and a careful evaluation of new ( possibly unresolved ) sources ( or source populations ) will improve the sensitivity for a dm search.
we present an analysis of the close double degenerate nltt12758, which is comprised of a magnetic white dwarf with a field of about 3.1 mg and an apparently non - magnetic white dwarf.   we measured an orbital period of 1.154 days and found that the magnetic white dwarf is spinning around its axis with a period of 23 minutes.   an analysis of the atmospheric parameters has revealed that the cooling ages of the two white dwarfs are comparable, suggesting that they formed within a short period of time from each other.   our modelling indicates that the non - magnetic white dwarf is more massive ( @xmath0 ) than its magnetic companion ( @xmath1 ) and that the total mass of the system is higher than the chandrasekhar mass.   although the stars will not come into contact over a hubble time, when they do come into contact, dynamically unstable mass transfer will take place leading to either an accretion induced collapse into a rapidly spinning neutron star or a type ia supernova.       stars : magnetic fields  stars : individual : nltt12758  white dwarfs  binaries : close
we report new observations with the very large array, atacama large millimeter array, and submillimeter array at frequencies from 1.0 to 355 ghz of the galactic center black hole, sagittarius a*. these observations were conducted between october 2012 and november 2014.   while we see variability over the whole spectrum with an amplitude as large as a factor of 2 at millimeter wavelengths, we find no evidence for a change in the mean flux density or spectrum of sgr a * that can be attributed to interaction with the g2 source.   the absence of a bow shock at low frequencies is consistent with a cross - sectional area for g2 that is less than @xmath0 @xmath1.   this result fits with several model predictions including a magnetically arrested cloud, a pressure - confined stellar wind, and a stellar photosphere of a binary merger.   there is no evidence for enhanced accretion onto the black hole driving greater jet and/or accretion flow emission.   finally, we measure the millimeter wavelength spectral index of sgr a * to be flat ; combined with previous measurements, this suggests that there is no spectral break between 230 and 690 ghz.   the emission region is thus likely in a transition between optically thick and thin at these frequencies and requires a mix of lepton distributions with varying temperatures consistent with stratification.
at low temperatures the phase diagram for the quantum hall effect has a powerful symmetry arising from the law of corresponding states.   this symmetry gives rise to an infinite order discrete group which is a generalisation of kramers - wannier duality for the two dimensional ising model.   the duality group, which is a subgroup of the modular group, is analysed and it is argued that there is a quantitative difference between a situation in which the spin splitting of electron energy levels is comparable to the cyclotron energy and one in which the spin splitting is much less than the cyclotron energy. in the former case the group of symmetries is larger than in the latter case.   these duality symmetries are used to constrain the scaling functions of the theory and, under an assumption of complex meromorphicity, a unique functional form is obtained for the crossover of the conductivities between hall states as a function of the external magnetic field. this analytic form is shown to give good agreement with experimental data.   the analysis requires a consideration of the way in which longitudinal resistivities are extracted from the experimentally measured longitudinal resistances and a novel method is proposed for determining the correct normalisation for the former.
we analyze the transport properties of a semiconductor based bilayer system under non - equilibrium conditions with special emphasis on the charge transfer statistics in the regime dominated by the exciton transport.   we consider two different models. in one of them   the transport occurs incoherently and is dominated by incoherent tunneling processes of individual excitons, while in the other system no disorder is present and transport processes are fully coherent.   we find that the strength of cross correlations of currents in different layers is only insignificantly affected by the disorder and shows up similar behaviour in both systems.   we discuss possible experimental realizations and make predictions for measurable quantities.
a short gamma - ray burst grb 090510 detected by _ fermi _ shows an extra spectral component between 10 mev and 30 gev, an addition to a more usual low - energy ( @xmath0 mev ) band component. in general, such an extra component could originate from accelerated protons.   in particular, inverse compton emission from secondary electron - positron pairs and proton synchrotron emission are competitive models for reproducing the hard spectrum of the extra component in grb 090510. here, using monte carlo simulations, we test the hadronic scenarios against the observed properties. to reproduce the extra component around gev with these models,   the proton injection isotropic - equivalent luminosity is required to be larger than @xmath1 erg@xmath2s.   such large proton luminosities are a challenge for the hadronic models.
an approach, recently proposed to calculate the nucleon generalized parton distributions ( gpds ) in a constituent quark model ( cqm ) scenario, in which the constituent quarks are taken as complex systems, is used to obtain helicity - dependent gpds.   they are obtained from the wave functions of the non relativistic cqm of isgur and karl, _ convoluted _ with the helicity - dependent gpds of the constituent quarks themselves.   the latter are modelled by using the polarized structure functions of the constituent quark, the double distribution representation of gpds, and a phenomenological constituent quark form factor.   the present approach permits to access a kinematical range corresponding to both the dokshitzer - gribov - lipatov - altarelli - parisi and the efremov - radyushkin - brodsky - lepage regions, for small values of the momentum transfer and of the skewedness parameter. in this kinematical region  , the present calculation represents a prerequisite for the evaluation of cross sections relevant to deeply virtual compton scattering.   in particular, we have calculated the leading twist helicity - dependent gpd @xmath0 and, from our expressions, its general relations with the non relativistic definition of the axial form factor and with the leading twist polarized quark density are consistently recovered.   l o # 1 # 1
in this work we describe the latest results for the measurements of the hyperfine structure of antiprotonic @xmath0he.   two out of four measurable super - super - hyperfine sshf transition lines of the @xmath1 state of antiprotonic @xmath0he were observed.   the measured frequencies of the individual transitions are @xmath2  ghz and @xmath3  ghz, with an increased precision of about 43% and 25% respectively compared to our first measurements with antiprotonic @xmath0he [ s. friedreich _   et al. _,   phys.   lett.   b 700 ( 2011 ) 16 ]. they are less than 0.5  mhz higher with respect to the most recent theoretical values, still within their estimated errors.   although the experimental uncertainty for the difference of @xmath4  ghz between these frequencies is large as compared to that of theory, its measured value also agrees with theoretical calculations.   the rates for collisions between antiprotonic helium and helium atoms have been assessed through comparison with simulations, resulting in an elastic collision rate of @xmath5  mhz and an inelastic collision rate of @xmath6  mhz.    version
the recent analysis on noncommutative geometry, showing quantization of the volume for the riemannian manifold entering the geometry, can support a view of quantum mechanics as arising by a stochastic process on it.   a class of stochastic processes can be devised, arising as fractional powers of an ordinary wiener process, that reproduce in a proper way a stochastic process on a noncommutative geometry.   these processes are characterized by producing complex values and so, the corresponding fokker  planck equation resembles the schrdinger equation. indeed, by a direct numerical check, one can recover the kernel of the schrdinger equation starting by an ordinary brownian motion.   this class of stochastic processes needs a clifford algebra to exist. in four dimensions,   the full set of dirac matrices is needed and the corresponding stochastic process in a noncommutative geometry is easily recovered as is the dirac equation in the klein   gordon form being it the fokker   planck equation of the process.
a statistical scenario is proposed to explain the @xmath0-ray variability and flares of the crab nebula, which were observed recently by the fermi / lat. in this scenario electrons   are accelerated in a series of knots, whose sizes follow a power - law distribution.   these knots presumably move outwards from the pulsar and have a distribution in the doppler boost factor.   the maximal electron energy is assumed to be proportional to the size of the knot.   fluctuations at the highest energy end of the overall electron distribution will result in variable @xmath0-ray emission via the synchrotron process in the @xmath1 mev range.   since highly boosted larger knots are rarer than smaller knots, the model predicts that the variability of the synchrotron emission increases with the photon energy.   we realize such a scenario with a monte - carlo simulation and find that the model can reproduce both the two @xmath0-ray flares over a period of @xmath2 year and the monthly scale @xmath0-ray flux fluctuations as observed by the fermi / lat.   the observed @xmath0-ray spectra in both the steady and flaring states are also well reproduced.
comparison of the observed evolution of the ly - alpha transmitted flux in the spectra of four highest redshift quasars discovered by sloan survey with the theoretical prediction for this evolution based on the state - of - the - art numerical simulations of cosmological reionization already allows one to constrain the redshift of reionization to @xmath0, where systematic and random errors are given respectively.   -0.5 in # 1/#1    # 1        cosmology : theory - cosmology : large - scale structure of universe - galaxies : formation - galaxies : intergalactic medium
we have analyzed available optical data for au in the mid - infrared range which is important for a precise prediction of the casimir force.   significant variation of the data demonstrates genuine sample dependence of the dielectric function.   we demonstrate that the casimir force is largely determined by the material properties in the low frequency domain and argue that therefore the precise values of the drude parameters are crucial for an accurate evaluation of the force.   these parameters can be estimated by two different methods, either by fitting real and imaginary parts of the dielectric function at low frequencies, or via a kramers - kronig analysis based on the imaginary part of the dielectric function in the extended frequency range.   both methods lead to very similar results.   we show that the variation of the casimir force calculated with the use of different optical data can be as large as 5% and at any rate can not be ignored. to have a reliable prediction of the force with a precision of 1%, one has to measure the optical properties of metallic films used for the force measurement.
we present the first investigation of the blue straggler star ( bss ) population in two isolated dwarf spheroidal galaxies of the local group, cetus and tucana.   deep hst / acs photometry allowed us to identify samples of 940 and 1214 candidates, respectively.   the analysis of the star formation histories of the two galaxies suggests that both host a population of bsss.   specifically, if the bss candidates are interpreted as young main sequence stars, they do not conform to their galaxy s age - metallicity relationship.   the analysis of the luminosity function and the radial distributions support this conclusion, and suggest a non - collisional mechanism for the bss formation, from the evolution of primordial binaries.   this scenario is also supported by the results of new dynamical simulations presented here.   both galaxies coincide with the relationship between the bss frequency and the absolute visual magnitude m@xmath0 found by @xcite.   if this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of bsss and galaxies hosting truly young populations.
an evolution of luminosity of galaxies in emission lines or wavelength ranges in which they are sensitive to the star formation process is caused by burning out of the most massive o - class stars during a few million years after a starburst.   we study the impact of this effect on the luminosity function ( lf ) of a sample of star - forming galaxies.   we introduce several types of lfs : an initial lf after a starburst, current, time - averaged and sample ones.   we find the relations between them in general and specify them in the case of the luminosity evolution law proposed for the luminous compact galaxies.   we obtain the sample lf for the cases the initial one is described by the pure schechter function or the log - normal distribution and analyze the properties of these lfs. as a result we get two new types of lfs to fit the lf of a sample of star - forming galaxies.
in this paper we address the topic of inelastic electron scattering in mesoscopic quantum transport. for systems where only elastic scattering is present, landauer theory provides an adequate description of transport that relates the electronic current to single - particle transmission and reflection probabilities.   a formalism proposed recently by bon@xmath0a and trugman facilitates the calculation of the one - electron transmission and reflection probabilities for _ inelastic _ processes in mesoscopic conductors connected to one - dimensional ideal leads. building on their work  , we have developed a self - consistent procedure for the evaluation of the non - equilibrium electron distributions in ideal leads connecting such mesoscopic conductors to electron reservoirs at finite temperatures and voltages.   we evaluate the net electronic current flowing through the mesoscopic device by utilizing these non - equilibrium distributions.   our approach is a generalization of landauer theory that takes account of the pauli exclusion principle for the various competing elastic and inelastic processes while satisfying the requirement of particle conservation. as an application   we examine the influence of elastic and inelastic scattering on conduction through a two site molecular wire with longitudinal phonons using the su - schrieffer - heeger model of electron - phonon coupling.
we are describing a new multi - fibre positioner, mefos, that was in general use at the la silla observatory, and implemented at the prime focus of the eso 3.6 m telescope.   it is an arm positioner using 29 arms in a one degree field.   each arm is equipped with an individual viewing system for accurate setting and carries two spectroscopic fibres, one for the astronomical object and the other one for the sky recording needed for sky subtraction.   the spectral fibres intercept 2.5 arcsec on the sky and run from the prime focus to the cassegrain, where the b&c spectrograph is located. after describing the observational procedure, we present the first scientific results.
we consider the following _ network computation problem_. in an acyclic network, there are multiple source nodes, each generating multiple messages, and there are multiple sink nodes, each demanding a function of the source messages.   the network coding problem corresponds to the case in which every demand function is equal to some source message, i.e., each sink demands some source message.   connections between network coding problems and matroids have been well studied. in this work,   we establish a relation between network computation problems and representable matroids.   we show that a network computation problem in which the sinks demand linear functions of source messages admits a scalar linear solution if and only if it is matroidal with respect to a representable matroid whose representation fulfills certain constraints dictated by the network computation problem.   next, we obtain a connection between network computation problems and functional dependency relations ( fd - relations ) and show that fd - relations can be used to characterize network computation problem with arbitrary ( not necessarily linear ) function demands as well as nonlinear network codes.
the composite torsional ultrasonic oscillator, a versatile experimental system, can be used to investigate slip of newtonian fluid at a smooth surface.   a rigorous analysis of slip - dependent damping for the oscillator is presented.   initially, the phenomenon of finite surface slip and the slip length are considered for a half - space of newtonian fluid in contact with a smooth, oscillating solid surface.   definitions are revisited and clarified in light of inconsistencies in the literature.   we point out that, in general oscillating flows, navier s slip length @xmath0 is a complex number.   an intuitive velocity discontinuity parameter of unrestricted phase is used to describe the effect of slip on measurement of viscous shear damping.   the analysis is applied to the composite oscillator and preliminary experimental work for a 40  khz oscillator is presented.   the non - slip boundary condition ( nsbc ) has been verified for a hydrophobic surface in water to within @xmath1  nm of @xmath2  nm. experiments were carried out at shear rate amplitudes between 230 and 6800  s@xmath3, corresponding to linear displacement amplitudes between 3.2 and 96  nm.   +   +   +   +   +   +   +    receipt date : 6 september 2007 + pacs numbers : 83.50.lh, 47.80.-v, 68.08.-p +
in the present work, ternary special quasirandom structures ( sqss ) for a fcc solid solution phase are generated at different compositions, @xmath0 and @xmath1, @xmath2, whose correlation functions are satisfactorily close to those of a random fcc solution.   the generated sqss are used to calculate the mixing enthalpy of the fcc phase in the ca - sr - yb system.   it is observed that first - principles calculations of all the binary and ternary sqss in the ca - sr - yb system exhibit very small local relaxation. it is concluded that the fcc ternary sqss can provide valuable information about the mixing behavior of the fcc ternary solid solution phase.   the sqss presented in this work can be widely used to study the behavior of ternary fcc solid solutions.
applications of variational methods are typically restricted to conservative systems. some extensions to   dissipative systems have been reported too but require _ ad  hoc _ techniques such as artificial doubling of variables. here, a different approach is proposed.   we show that, for a broad class of dissipative systems of practical interest, variational principles can be formulated using _ constant _ lagrange multipliers and lagrangians nonlocal in time, which allow treating reversible and irreversible dynamics on the same footing. a general variational theory of linear dispersion is formulated as an example.   in particular, we present a variational formulation for linear geometrical optics in a general dissipative medium, which is allowed to be nonstationary, inhomogeneous, nonisotropic, and exhibit both temporal and spatial dispersion simultaneously.
it has recently been suggested that collapse of neutron stars induced by a phase transition to quark matter can be a considerable source of gravitational waves with khz frequencies.   we demonstrate that if about one percent of all neutron stars undergo this process, the resulting cosmological gravitational wave background would reach about @xmath0 times the critical density.   the background would peak at khz frequencies and could have an observationally significant tail down to hz frequencies.   it would be comparable or higher than other astrophysical backgrounds, for example, from ordinary core collapse supernovae, from r - mode instabilities in rapidly rotating neutron stars, or from magnetars.   the scenario is consistent with cosmological backgrounds in neutrinos and photons.   * keywords * : gravity waves / theory, neutron stars
within the framework of boltzmann transport equation with a bhatnagar - gross - krook ( bgk ) collisional kernel, we study the wake potential induced by fast partons traveling through the high - temperature qcd plasma which is anisotropic in momentum - space.   we calculate the dielectric response function of a collisional anisotropic quark - gluon plasma ( aqgp ) for small @xmath0 ( anisotropic parameter ) limit. using this,   the wake potential for various combinations of the anisotropy parameter ( @xmath0 ) and the collision rate ( @xmath1 ) is evaluated both for parallel and perpendicular directions of motion of the fast parton.   it is seen that the inclusion of the collision modifies the wake potential and the amount as well as the nature of the potential depends on the combinations of @xmath0 and @xmath1.
a new conceptual key generation scheme is presented by using intrinsic quantum correlations of single photons between alice and bob.   the intrinsic bi - partite correlation functions allow key bit to be generated through high level communication language i.e. a key bit is directly encoded to shared correlation functions not to the state and detection of a photon at bob does not mean key bit.   these make the scheme robust against intercept - resend attack because alice and bob can always check the errors in their measurements and reveal the presence of eve in their channel without leaking any key bit information.   the scheme is strictly relied on the perfect beam splitter and mean photon number less than 1, where more than one photon in a coherent pulse will introduce more errors in bob even without the presence of eve. from the percentage of errors in bob  , we can estimate the amount of information will be leaked to eve in the photon - number splitting attack.   this scheme can preserve the randomness of phase - randomized light source for doubling the communication distance as in original ekert s protocol and providing the raw key generation rate a factor of 2 higher than weak coherent light protocols.
the hypothesis that living systems can benefit from operating at the vicinity of critical points has gained momentum in recent years.   criticality may confer an optimal balance between too ordered and exceedingly noisy states. here   we present a model, based on information theory and statistical mechanics, illustrating how and why a community of agents aimed at understanding and communicating with each other converges to a globally coherent state in which all individuals are close to an internal critical state, i.e. at the borderline between order and disorder.   we study both analytically and computationally the circumstances under which criticality is the best possible outcome of the dynamical process, confirming the convergence to critical points under very generic conditions.   finally, we analyze the effect of cooperation ( agents trying to enhance not only their fitness, but also that of other individuals ) and competition ( agents trying to improve their own fitness and to diminish those of competitors ) within our setting.   the conclusion is that, while competition fosters criticality, cooperation hinders it and can lead to more ordered or more disordered consensual outcomes.
we analyze the possibility of defining infinite - dimensional manifolds as ringed spaces.   more precisely, we consider three definitions of manifolds modeled on locally convex spaces : in terms of charts and atlases, in terms of ringed spaces, and in terms of functored spaces, as introduced by douady in his thesis.   it is shown that for large classes of locally convex model spaces ( containing frchet spaces and duals of frchet - schwartz spaces ), the three definitions are actually equivalent.   the equivalence of the definition via charts with the definition via ringed spaces is based on the fact that for the classes of model spaces under consideration, smoothness of maps turns out to be equivalent to their _ scalarwise smoothness _ ( that is, the smoothness of their composition with smooth real - valued functions ). +
the dama / libra  phase1 and the former dama / nai data ( cumulative exposure @xmath0 ton @xmath1 yr, corresponding to 14 annual cycles ) give evidence at 9.3 @xmath2 c.l. for the presence of dark matter ( dm ) particles in the galactic halo, on the basis of the exploited model independent dm annual modulation signature by using highly radio - pure nai(tl ) target. results and comparisons will be shortly addressed as well as perspectives of the presently running dama / libra - phase2.   finally, some arguments arisen in the discussion section of this workshop are mentioned in the appendix.
we study the mass at the origin in the uncorrelated sabr stochastic volatility model, and derive several tractable expressions, in particular when time becomes small or large. as an application   in fact the original motivation for this paper  we derive small - strike expansions for the implied volatility when the maturity becomes short or large. these formulae, by definition arbitrage free,   allow us to quantify the impact of the mass at zero on existing implied volatility approximations, and in particular how correct / erroneous these approximations become.
we compare classical versus quantum electron transport in recently investigated magnetic focusing devices [ s. bhandari et al.  , nano lett.  16, 1690 ( 2016 ) ] exposed to the perturbing potential of a scanning gate microscope ( sgm ).   using the landauer - bttiker formalism for a multi - terminal device, we calculate resistance maps that are obtained as the sgm tip is scanned over the sample  . there are three unique regimes in which the scanning tip can operate ( focusing, repelling, and mixed regime ) which are investigated.   tip interacts mostly with electrons with cyclotron trajectories passing directly underneath it, leaving a trail of modified current density behind it.   other ( indirect ) trajectories become relevant when the tip is placed near the edges of the sample, and current is scattered between the tip and the edge.   we also discuss possible explanations for spatial asymmetry of experimentally measured resistance maps, and connect it with specific configurations of the measuring probes.
we study the statistical properties of the 1st year wmap data on different scales using the spherical mexican hat wavelet transform.   consistent with the results of vielva et al.   ( 2003 ) we find a deviation from gaussianity in the form of kurtosis of wavelet coefficients on @xmath0 scales in the southern galactic hemisphere.   this paper extends the work of vielva et al. as follows.   we find that the non - gaussian signal shows up more strongly in the form of a larger than expected number of cold pixels and also in the form of scale - scale correlations amongst wavelet coefficients.   we establish the robustness of the non - gaussian signal under more wide - ranging assumptions regarding the galactic mask applied to the data and the noise statistics.   this signal is unlikely to be due to the usual quadratic term parametrized by the non - linearity parameter @xmath1.   we use the skewness of the spherical mexican hat wavelet coefficients to constrain @xmath1 with the 1st year wmap data.   our results constrain @xmath1 to be @xmath2 at 68% confidence, and less than 280 at 99% confidence.
we present results for the masses and decay constants of the light mesons in quenched qcd using the standard gluon action and a tadpole  improved sw  clover fermionic action to reduce discretisation errors.   the calculation has been carried out at fixed volume and three lattice spacings corresponding to @xmath0, @xmath1 and @xmath2.   we make comparisons with the conventional sw  clover scheme.   we use our results to extract continuum limits and to quantify the size of discretisation errors at smaller @xmath3-values.   glasgow preprint gutpa 9592 + liverpool preprint lth 359 + hep - lat/9509083    masses and decay constants of the light mesons in the quenched approximation using the tadpole  improved sw - clover action.   + _ ukqcd collaboration _ + * c.  michael * + damtp, university of liverpool, liverpool, l69 3bx, u.k.    *   h.  shanahan * + department of physics and astronomy, university of glasgow, glasgow, g12 8qq, scotland, u.k.
the space - borne missions corot and _ kepler _ have opened a new era in stellar physics, especially for evolved stars, with precise asteroseismic measurements that help determine precise stellar parameters and perform ensemble asteroseismology.   this paper deals with the quality of the information that we can retrieve from the oscillations.   it focusses on the conditions for obtaining the most accurate measurement of the radial and non - radial oscillation patterns.   this accuracy is a prerequisite for making the best with asteroseismic data. from radial modes,   we derive proxies of the stellar mass and radii with an unprecedented accuracy for field stars. for dozens of subgiants and thousands of red giants, the identification of mixed modes ( corresponding to gravity waves propagating in the core coupled to pressure waves propagating in the envelope ) indicates unambiguously their evolutionary status. as probes of the stellar core  , these mixed modes also reveal the internal differential rotation and show the spinning down of the core rotation of stars ascending the red giant branch. a toy model of the coupling of waves constructing mixed modes   is exposed, for illustrating many of their features.
weak gravitational lensing causes subtle changes in the apparent shapes of galaxies due to the bending of light by the gravity of foreground masses. by measuring the shapes of large numbers of galaxies ( millions in recent surveys, up to tens of billions in future surveys ) we can infer the parameters that determine cosmology.   imperfections in the detectors used to record images of the sky can introduce changes in the apparent shape of galaxies, which in turn can bias the inferred cosmological parameters. in this paper   we consider the effect of two widely discussed sensor imperfections : tree - rings, due to impurity gradients which cause transverse electric fields in the charge - coupled devices ( ccd ), and pixel - size variation, due to periodic ccd fabrication errors.   these imperfections can be observed when the detectors are subject to uniform illumination ( flat field images ).   we develop methods to determine the spurious shear and convergence ( due to the imperfections ) from the flat - field images.   we calculate how the spurious shear when added to the lensing shear will bias the determination of cosmological parameters.   we apply our methods to candidate sensors of the large synoptic survey telescope ( lsst ) as a timely and important example, analyzing flat field images recorded with lsst prototype ccds in the laboratory.   we find that tree - rings and periodic pixel - size variation present in the lsst ccds will introduce negligible bias to cosmological parameters determined from the lensing power spectrum, specifically @xmath0, @xmath1 and @xmath2.
in the recent years, the discovery of a new class of galactic transients with fast and bright flaring x   ray activity, the supergiant fast x   ray transients, has completely changed our view and comprehension of massive x  ray binaries.   these objects display x  ray outbursts which are difficult to be explained in the framework of standard theories for the accretion of matter onto compact objects, and could represent a dominant population of x  ray binaries.   i will review their main observational properties ( neutron star magnetic field, orbital and spin period, long term behavior, duty cycle, quiescence and outburst emission ), which pose serious problems to the main mechanisms recently proposed to explain their x  ray behaviour.   i will discuss both present results and future perspectives with the next generation of x  ray telescopes.   x  ray binaries, x  ray sources, accretion and accretion disks, supergiants
we examine the star - forming history ( sfh ) of the m31 disk during the past few hundred myr. the luminosity functions ( lfs ) of main sequence stars at distances r@xmath0 kpc ( i.e. @xmath1 disk scale lengths ) are matched by models that assume a constant star formation rate ( sfr ).   however, at smaller r@xmath2 the lfs suggest that during the past @xmath3 myr the sfr was @xmath4 higher than during the preceding @xmath5 myr.   the rings of cool gas that harbor a significant fraction of the current star - forming activity are traced by stars with ages @xmath5 myr, indicating that ( 1 ) these structures have ages of at least 100 myr, and ( 2 ) stars in these structures do not follow the same relation between age and random velocity as their counterparts throughout the disks of other spiral galaxies, probably due to the inherently narrow orbital angular momentum distribution of the giant molecular clouds in these structures.   the distribution of evolved red stars is not azimuthally symmetric, in the sense that their projected density along the north east segment of the major axis is roughly twice that on the opposite side of the galaxy.   the north east arm of the major axis thus appears to be a fossil star - forming area that dates to intermediate epochs.   such a structure may be the consequence of interactions with a companion galaxy.   = 1.0 cm
the line shapes of giant dipole resonance ( gdr ) in the decay of the compound nucleus @xmath0mo, which is formed after the fusion - evaporation reaction @xmath1ti @xmath2 @xmath3ca at various excitation energies @xmath4 from 58 to 308 mev, are generated by averaging the gdr strength functions predicted within the phonon damping model ( pdm ) using the empirical probabilities for temperature and angular momentum.   the average strength functions are compared with the pdm strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular - momentum probability distributions, respectively.   it is seen that these two ways of generating the gdr linear line shape yield very similar results.   it is also shown that the gdr width approaches a saturation at angular momentum @xmath5 50@xmath6 at @xmath7 4 mev and at @xmath5 70@xmath6 at any @xmath8.
for scalar and electromagnetic fields we evaluate the vacuum expectation value of the energy - momentum tensor induced by a curved boundary in the robertson  walker spacetime with negative spatial curvature. in order to generate the vacuum densities we use the conformal relation between the robertson  walker and rindler spacetimes and the corresponding results for a plate moving by uniform proper acceleration through the fulling  rindler vacuum. for the general case of the scale factor   the vacuum energy - momentum tensor is presented as the sum of the boundary free and boundary induced parts.
the conventional picture for the origin of the polarization of a supernova is based on a model of thomson or resonance scattering of photons traveling through an aspherical supernova atmosphere.   positive detection of intrinsic polarization in sn 1987a is then interpretated as evidence of an asymmetrical supernova atmosphere.   we show here a different view based on the scattering of the supernova light by a dusty circumstellar material ( csm ), or the `` light echo '' effect. at a given epoch after the explosion, the observed photons consist of both those propagating directly from the supernova and those scattered by dust particles in the csm.   polarized light can be produced if the distribution of the dust particles is aspherical.   the model can reproduce both the time evolution of the observed broad band polarization of sn 1987a and major features of the polarization spectra.   it is also successful in providing a natural model for the early infrared light curve, in particular the observed 30 day delay of the ir maximum compared to the maximum of the bolometric light curve.   1f(^,^ ) plus 2pt
a scheme is proposed to construct integer and fractional topological quantum states of fermions in two spatial dimensions.   we devise models for such states by coupling wires of non - chiral luttinger liquids of electrons, that are arranged in a periodic array. which inter - wire couplings are allowed is dictated by symmetry and the compatibility criterion that they can simultaneously acquire a finite expectation value, opening a spectral gap between the ground state(s ) and all excited states in the bulk.   first, with these criteria at hand, we reproduce the tenfold classification table of integer topological insulators, where their stability against interactions becomes immediately transparent in the luttinger liquid description.   second, we construct an example of a strongly interacting fermionic topological phase of matter with short - range entanglement that lies outside of the tenfold classification.   third, we expand the table to long - range entangled topological phases with intrinsic topological order and fractional excitations.
we present the first rest - frame @xmath0  detection of a lyman break galaxy.   the data were obtained using the 16  imaging capability of the spitzer infrared spectrograph.   the target object, j134026.44 + 634433.2, is an extremely luminous lyman break galaxy at z=2.79 first identified in sloan digital sky survey spectra ( bentz, osmer, & weinberg 2004 ).   the source is strongly detected with a flux of @xmath1  mjy. combining spitzer and sdss photometry with supporting ground - based j- and k - band data, we show that the spectral energy distribution is consistent with an actively star - forming galaxy.   we also detect other objects in the spitzer field of view, including a very red mir source.   we find no evidence of a strong lens amongst the mir sources.
multi - line imaging of the nearby disk galaxy ngc  1482 with the taurus tunable filter ( ttf ) on the anglo - australian telescope reveals a remarkable hourglass - shaped  @xmath06583/h@xmath1 excitation structure suggestive of a galactic wind extending at least 1.5 kpc above and below the disk of the host galaxy.   long - slit spectroscopy confirms the existence of a large - scale outflow in this galaxy.   the entrained wind material has  @xmath06583/h@xmath1 ratios in excess of unity while the disk material is characterized by h  ii region - like line ratios indicative of a starburst.   expansion velocities of order 250 km s@xmath2 are detected in the wind material, and a lower limit of 2 @xmath3 10@xmath4 ergs is derived for the kinetic energy of the outflow based on the gas kinematics and the amount of ionized material entrained in the outflow.   this is the first time to our knowledge that a galactic wind is discovered using excitation maps.   this line ratio technique represents a promising new way to identify wind galaxy candidates before undergoing more time - consuming spectroscopic follow - ups.   this method of selection may be particularly useful for samples of galaxies at moderate redshifts.
we have obtained @xmath0  pc resolution co and @xmath1  pc resolution  observations of the dwarf spiral galaxy ngc  4605.   we use them to derive a high resolution rotation curve and study the central density profile of ngc  4605 s dark matter halo.   we find that these observations do not agree with the predictions of most high resolution cold dark matter calculations.   we investigate two extreme cases : 1 ) ngc  4605 has a maximal exponential disk, that we model using @xmath2band observations and remove to study the structure of its dark matter halo, and 2 ) ngc  4605 is dark matter dominated and its disk is dynamically negligible. because the mass  to  light ratio of the maximal disk is already very low we favor the first solution, which indicates the halo has one component with a density profile @xmath3 out to @xmath4 kpc. in the second case,   the rotation curve requires the presence of two components : a small ( @xmath5 pc ) core surrounded by a much steeper @xmath6 halo.   removal of intermediate ( submaximal ) disks does not ameliorate the discrepancy between the predictions and the observations.
the eigenvalue structure of the quantum transfer matrix is known to encode essential information about the elementary excitations. here   we study transfer matrices of quantum states in a topological phase using the tensor network formalism.   we demonstrate that topological quantum order requires a particular type of ` symmetry breaking'for the fixed point subspace of the transfer matrix, and relate physical anyon excitations to domain wall excitations at the level of the transfer matrix. a topological phase transition to a trivial phase   triggers a change in the fixed point subspace to either a larger or smaller symmetry and we explain how this relates to a condensation or confinement of the corresponding anyon sectors.   the tensor network formalism enables us to determine the structure of the topological sectors in two - dimensional gapped phases very efficiently, therefore opening novel avenues for studying fundamental open questions related to anyon condensation.
we propose a quantum feedback scheme for the preparation and protection of photon number states of light trapped in a high-@xmath0 microwave cavity.   a quantum non - demolition measurement of the cavity field provides information on the photon number distribution.   the feedback loop is closed by injecting into the cavity a coherent pulse adjusted to increase the probability of the target photon number.   the efficiency and reliability of the closed - loop state stabilization is assessed by quantum monte - carlo simulations.   we show that, in realistic experimental conditions, fock states are efficiently produced and protected against decoherence.
we present chemical abundances for 17 elements in a sample of 11 red giant branch stars in ngc  6362 from uves spectra.   ngc  6362 is one of the least massive globulars where multiple populations have been detected, yet its detailed chemical composition has not been investigated so far.   ngc  6362 turns out to be a metal - intermediate ( =1.07@xmath00.01 dex ) cluster, with its @xmath1- and fe - peak elements content compatible with that observed in clusters with similar metallicity.   it also displays an enhancement in its s - process element abundances. among the light elements involved in the multiple populations phenomenon, only  shows star - to - star variations, while  and  do not show any evidence for abundance spreads. a differential comparison with m4  , a globular cluster with similar mass and metallicity, reveals that the two clusters share the same chemical composition.   this finding suggests that ngc  6362 is indeed a regular cluster, formed from gas that has experienced the same chemical enrichment of other clusters with similar metallicity.       globular clusters : individual ( ngc  6362 ) - stars : abundances - techniques : spectroscopic
the universal secure network coding presented by silva et al. realizes secure and reliable transmission of a secret message over any underlying network code, by using maximum rank distance codes.   inspired by their result, this paper considers the secure network coding based on arbitrary linear codes, and investigates its security performance and error correction capability that are guaranteed independently of the underlying network code.   the security performance and error correction capability are said to be _ universal _ when they are independent of underlying network codes.   this paper introduces new code parameters, the relative dimension / intersection profile ( rdip ) and the relative generalized rank weight ( rgrw ) of linear codes.   we reveal that the universal security performance and universal error correction capability of secure network coding are expressed in terms of the rdip and rgrw of linear codes. the security and error correction of existing schemes   are also analyzed as applications of the rdip and rgrw.
we study features in the optically detected magnetic resonance ( odmr ) signals associated with negatively charged nitrogen - vacancy ( nv@xmath0 ) centers coupled to other paramagnetic impurities in diamond.   our results are important for understanding odmr line shapes and for optimization of devices based on nv@xmath0 centers.   we determine the origins of several side features to the unperturbed nv@xmath0 magnetic resonance by studying their magnetic field and microwave power dependences.   side resonances separated by around 130 mhz are due to hyperfine coupling between nv@xmath0 centers and nearest - neighbor @xmath1c nuclear spins.   side resonances separated by approximately \{40, 260, 300 } mhz are found to originate from simultaneous spin flipping of nv@xmath0 centers and single substitutional nitrogen atoms.   all results are in agreement with the presented theoretical calculations.
a warm fermionic ads star under a homogeneous magnetic field is explored.   we obtain the relativistic landau levels by using dirac equation and use the tolman - oppenheimer - volkoff  ( tov ) equation to study the physical profiles of the star.   bulk properties such as sound speed, adiabatic index, and entropy density within the star are calculated analytically and numerically.   bulk temperature increases the mass limit of the ads star but external magnetic field has the opposite effect.   the results are partially interpreted in terms of the pre - thermalization process of the gauge matter at the ads boundary after the mass injection.   the entropy density is found to demonstrate similar temperature dependence as the magnetic black brane in the ads in certain limits regardless of the different nature of the bulk and hawking temperatures.   total entropy of the ads star is also found to be an increasing function of the bulk temperature and a decreasing function of the magnetic field, similar behaviour to the mass limit.   since both total entropy and mass limit are global quantities, they could provide some hints to the value of entropy and energy of the dual gauge matter before and during the thermalization.   keywords : holographic principle, ads star, mass limit, thermalization
we illustrate the mass and charge renormalization procedures in quantum field theory using, as an example, a simple model of interacting electrons and photons. it is shown how addition of infinite renormalization counterterms to the hamiltonian helps to obtain finite and accurate results for the @xmath0-matrix. in order to remove the ultraviolet divergences from the hamiltonian  , we apply the greenberg - schweber `` dressing transformation '' and the gazek - wilson `` similarity renormalization ''.   the resulting `` dressed particle '' hamiltonian is finite in all orders of the perturbation theory and yields accurate @xmath0-matrix and bound state energies.   the bare and virtual particles are removed from the theory, and physical dressed particles interact via direct action - at - a - distance.
using a direct simulation monte carlo technique, we have studied the time evolution of a cold atom cloud interacting with a time dependent radio frequency ( rf ) dressed state potential.   exposure of a cloud of @xmath0 atoms, trapped in a quadrupole magnetic trap, to a time dependent rf - field with increasing amplitude and decreasing frequency, shows a variation in the number of trapped atoms and the overall shape of the atom cloud.   it is shown by simulations that, initially at lower rf - field strength, the rf - field results in ejection of atoms from the trap, leading to evaporative cooling of the atom cloud.   later, at higher rf - field strength, the atoms undergo the non - adiabatic landau - zener ( lz ) transitions, which leads to their trapping in an rf - dressed state potential of toroidal shape.   the results of simulations explain the experimentally observed results.   the simulations can be useful to predict the atom cloud dynamics and trapping geometries with other forms of the potential.
we consider a bose - einstein condensate confined in a `` mexican hat '' potential, with a quartic minus quadratic radial dependence.   we find conditions under which the ground state is annular in shape, with a hole in the center of the condensate.   rotation leads to the appearance of stable multiply - quantized vortices, giving rise to a superfluid flow around the ring.   the collective modes of the system are explored both numerically and analytically using the gross - pitaevskii and hydrodynamic equations.   potential experimental schemes to detect vorticity are proposed and evaluated, which include measuring the splitting of collective mode frequencies, observing expansion following release from the trap, and probing the momentum distribution of the condensate.
although observations of circumstellar shock interactions around supernovae are generally consistent with a @xmath0 wind surrounding the progenitor star, this is not true for grb ( gamma - ray burst ) afterglows.   however, grb 991208 and grb 000301c may be consistent with wind interaction if the injection particle spectrum is a broken power law.   circumstellar dust echos can place constraints on supernova and grb progenitors, but have been clearly observed only around sn 1987a.   excess emission observed in two grb afterglows is more likely to have a supernova origin.   an interstellar dust echo, causing the light curve to flatten out, is a possibility for grb afterglows, but is not likely to be observable.
we examine linear and quasi - liner stages of cherenkov - drift instability in the relativistic magnetized electron - positron plasma.   the external magnetic field lines are assumed to be slightly curved. in this case   the curvature drift of relativistic beam particles plays decisive role in the development of the instability.   quasi - linear relaxation of the relativistic beam leads to diffusion of the resonant particles in the momenta space.   the expressions for diffusion coefficients of cherenkov - drift instability are obtained.
this work advocates eulerian motion representation learning over the current standard lagrangian optical flow model.   eulerian motion is well captured by using phase, as obtained by decomposing the image through a complex - steerable pyramid.   we discuss the gain of eulerian motion in a set of practical use cases : ( i ) action recognition, ( ii ) motion prediction in static images, ( iii ) motion transfer in static images and, ( iv ) motion transfer in video.   for each task we motivate the phase - based direction and provide a possible approach.
we examine the local density of states of an impurity level or a quantum dot coupled to a fractional quantum hall edge, or to the end of a single one - dimensional luttinger - liquid lead.   effects of an ohmic dissipative bath are also taken into account. using both analytical and numerical techniques   we show that, in general, the density of states exhibits power - law frequency dependence near the fermi energy. in a substantial region of the parameter space   it simply reflects the behavior of the tunneling density of states at the end of a luttinger - liquid, and is insensitive either to the value of the dot - lead interaction or to the strength of dissipation ; otherwise it depends on these couplings too.   this behavior should be contrasted with the thermodynamic properties of the level, in particular, its occupancy, which were previously shown to depend on the various interactions in the system only through the corresponding fermi edge singularity exponent, and thus can not display any luttinger - liquid specific power - law.   hence, we can construct different models, some with and some without interactions in the wire ( but with equal fermi edge singularity exponents ), which would have very different level densities of states, although they all result in the same level population vs.  energy curves.
automated search for star clusters in @xmath0 data from 2mass catalog has been performed using the method developed by koposov et.   al ( 2008 ).   we have found and verified 153 new clusters in the interval of the galactic latitude @xmath1.   color excesses @xmath2, distance moduli and ages were determined for 130 new and 14 yet - unstudied known clusters. in this paper  , we publish a catalog of coordinates, diameters, and main parameters of all the clusters under study.   a special web - site available at http://ocl.sai.msu.ru has been developed to facilitate dissemination and scientific usage of the results.    
understanding customer buying patterns is of great interest to the retail industry and has shown to benefit a wide variety of goals ranging from managing stocks to implementing loyalty programs.   association rule mining is a common technique for extracting correlations such as _ people in the south of france buy ros wine _ or _   customers who buy pat also buy salted butter and sour bread. _ unfortunately, sifting through a high number of buying patterns is not useful in practice, because of the predominance of popular products in the top rules. as a result,   a number of `` interestingness '' measures ( over 30 ) have been proposed to rank rules.   however, there is no agreement on which measures are more appropriate for retail data.   moreover, since pattern mining algorithms output thousands of association rules for each product, the ability for an analyst to rely on ranking measures to identify the most interesting ones is crucial. in this paper,   we develop  ( comparative analysis of patterns ), a framework that provides analysts with the ability to compare the outcome of interestingness measures applied to buying patterns in the retail industry.   we report on how we used  to compare 34 measures applied to over 1,800 stores of intermarch, one of the largest food retailers in france.
we study the impact of the halo shape and geometry on the expected weakly interacting massive particle ( wimp ) dark matter annihilation signal from the galactic center. as the halo profile in the innermost region is still poorly constrained, we focus on geometrical distortions and consider different density behaviors like flat cores, cusps and spikes. we show that asphericity has a strong impact on the annihilation signal when the halo profile near the galactic center is flat, but becomes gradually less significant for cuspy profiles, and negligible in the presence of a central spike  . however, the astrophysical factor is strongly dependent on the wimp mass and annihilation cross - section in the latter case.
3ex    * abstract *    in this paper, we discuss a possibility of studying properties of dark energy in long baseline neutrino oscillation experiments.   we consider two types of models of neutrino dark energy.   for one type of models the scalar field is taken to be quintessence - like and for the other phantom - like. in these models   the scalar fields couple to the neutrinos to give rise to a spatially varying neutrino masses.   we will show that the two types of models predict different behaviors of the spatial variation of the neutrino masses inside earth and consequently result in different signals in long baseline neutrino oscillation experiments.
we report results important for the creation of a best - of - both - worlds quantum hybrid system consisting of a solid - state source of single photons and an atomic ensemble as quantum memory.   we generate single photons from a gaas quantum dot ( qd ) frequency - matched to the rb d2-transitions and then use the rb transitions to analyze spectrally the quantum dot photons.   we demonstrate lifetime - limited qd linewidths ( 1.42 ghz ) with both resonant and non - resonant excitation.   the qd resonance fluorescence in the low power regime is dominated by rayleigh scattering, a route to match quantum dot and rb atom linewidths and to shape the temporal wave packet of the qd photons.   noise in the solid - state environment is relatively benign : there is a blinking of the resonance fluorescence at mhz rates but negligible dephasing of the qd excitonic transition.   we therefore demonstrate significant progress towards the realization of an ideal solid - state source of single photons at a key wavelength for quantum technologies.
we present a new capacitive sensor for displacement measurement in a surface forces apparatus ( sfa ) which allows dynamical measurements in the range of @xmath0  hz.   this sensor measures the relative displacement between two macroscopic opaque surfaces over periods of time ranging from milliseconds to in principle an indefinite period, at a very low price and down to atomic resolution.   it consists of a plane capacitor, a high frequency oscillator, and a high sensitivity frequency to voltage conversion.   we use this sensor to study the nanorheological properties of dodecane confined between glass surfaces.   * keywords :* surface forces apparatus, capacitive sensor, nanorheology
_ ab initio _ calculations within the density - functional theory formalism are performed to investigate the chemical functionalization of a graphene - like monolayer of silicon  silicene  with b, n, al or p atoms.   the structural, electronic, magnetic and vibrational properties are reported.   the most preferable adsorption sites are found to be valley, bridge, valley and hill site for b, n, al and p adatoms, respectively. all the relaxed systems with adsorbed   / substituted atoms exhibit metallic behaviour with strongly bonded b, n, al, and p atoms accompanied by an appreciable electron transfer from silicene to the b, n and p adatom / substituent.   the al atoms exhibit opposite charge transfer, with n - type doping of silicene and weaker bonding.   the adatoms / substituents induce characteristic branches in the phonon spectrum of silicene, which can be probed by raman measurements. using molecular dynamics we found that the systems under study are stable up to at least t = 500 k.   our results demonstrate that silicene has a very reactive and functionalizable surface.
the galactic cosmic rays are the main source of ionization in the earth stratosphere and troposphere.   the induced by primary cosmic ray particles ionization is important in various processes related to atmospheric physics and chemistry, specifically the minor constituents.   the ion production in the atmosphere is enhanced compared to the average following major solar energetic particles events, specifically over the polar caps. during the solar cycle 23 we observed several strong ground level enhancements, one of the strongest among them been the bastille day event on 14 july 2000. in the work presented here   we apply a full monte carlo 3-d model in order to compute the cosmic ray induced ionization.   the model is based on atmospheric shower simulation with the planetocosmics code and the ion production rate is considered as a superposition of cosmic rays with galactic and solar origin.   the ion production rate is computed as a function of the altitude above the sea level and the short, mid and long term ionization effect relative to the average due to galactic cosmic rays is computed.
a soap film, or a flexible membrane without bending and torsional stiffness, that is confined in a cylinder is shown to be susceptible to a surface - tension - driven instability when it is stretched or twisted.   this leads to its breakdown and places an upper limit on the aspect ratio of such structures.   a simple analysis confirms the values for the critical aspect ratio of the stretched film found in both simulations and experiments on soap films, and this threshold decreases with increasing twist of the film.
we assume that the helium - i lines emitted by the massive binary system @xmath0 carinae are formed in the acceleration zone of the less - massive secondary star.   we calculate the doppler shift of the lines as a function of orbital phase and of several parameters of the binary system.   we find that a good fit is obtained if the helium lines are formed in the region where the secondary wind speed is @xmath1.   the acceptable binary eccentricity is in the range @xmath2, and the inclination angle ( the angle between a line perpendicular to the orbital plane and the line of sight ) is in the range @xmath3.   lower values of @xmath4 require higher values of @xmath5, and vice versa.   the binary system is oriented such that the secondary star is in our direction ( closer to us ) during periastron passage.   the orbital motion can account in part to the doppler shift of the peak in x - ray emission.
we compute the ground state energy of a massive scalar field in the background of a cylindrical shell whose potential is given by a delta function.   the zero point energy is expressed in terms of the jost function of the related scattering problem, the renormalization is performed with the help of the heat kernel expansion. the energy is found to be negative for attractive and for repulsive backgrounds as well.
in the weak - coupling limit, @xmath0, the partition function of simplicial quantum gravity is dominated by an ensemble of triangulations with the ratio @xmath1 close to the upper kinematic limit. for a combinatorial triangulation of the @xmath2sphere   this limit is @xmath3. defining an ensemble of _ maximal _ triangulations,   i.e.  triangulations that have the maximal possible number of vertices for a given volume, we investigate the properties of this ensemble in three dimensions using both monte carlo simulations and a strong - coupling expansion of the partition function, both for pure simplicial gravity and a with a suitable modified measure. for the latter   we observe a continuous phase transition to a _ crinkled _ phase and we investigate the fractal properties of this phase.   bi / th-98/38 + december 1998    _   g.  thorleifsson, p.  bialas and b.  petersson _   +    facultt fr physik, universitt bielefeld d-33615, bielefeld, germany +
the non - resonant interaction between the high - density excitons in a quantum well and a single mode cavity field is investigated. an analytical expression for the physical spectrum of the excitons   is obtained.   the spectral properties of the excitons, which are initially prepared in the number states or the superposed states of the two different number states by the resonant femtosecond pulse pumping experiment, are studied.   numerical study of the physical spectrum is carried out and a discussion of the detuning effect is presented.    2
we propose an efficient strategy to infer sparse hopfield network based on magnetizations and pairwise correlations measured through glauber samplings.   this strategy incorporates the @xmath0 regularization into the bethe approximation by a quadratic approximation to the log - likelihood, and is able to further reduce the inference error of the bethe approximation without the regularization.   the optimal regularization parameter is observed to be of the order of @xmath1 where @xmath2 is the number of independent samples.   the value of the scaling exponent depends on the performance measure.   @xmath3 for root mean squared error measure while @xmath4 for misclassification rate measure.   the efficiency of this strategy is demonstrated for the sparse hopfield model, but the method is generally applicable to other diluted mean field models. in particular, it is simple in implementation without heavy computational cost.
we demonstrate that the observed distribution of ` hot neptune'/`super - earth'systems is well reproduced by a model in which planet assembly occurs in situ, with no significant migration post - assembly.   this is achieved only if the amount of mass in rocky material is @xmath0@xmath1 interior to 1  au.   such a reservoir of material implies that significant radial migration of solid material takes place, and that it occur before the stage of final planet assembly.   the model not only reproduces the general distribution of mass versus period, but also the detailed statistics of multiple planet systems in the sample.   we furthermore demonstrate that cores of this size are also likely to meet the criterion to gravitationally capture gas from the nebula, although accretion is rapidly limited by the opening of gaps in the gas disk. if the mass growth is limited by this tidal truncation, then the scenario sketched here naturally produces neptune - mass objects with substantial components of both rock and gas, as is observed.   the quantitative expectations of this scenario are that most planets in the ` hot neptune / super - earth'class inhabit multiple - planet systems, with characteristic orbital spacings.   the model also provides a natural division into gas - rich ( hot neptune ) and gas - poor ( super - earth ) classes at fixed period. the dividing mass ranges from @xmath2 at 10  day orbital periods to @xmath3 at 100  day orbital periods. for orbital periods @xmath4  days, the division is less clear because a gas atmosphere may be significantly eroded by stellar radiation.
motivated by the recently proposed parallel orbital - updating approach in real space method @xcite, we propose a parallel orbital - updating based plane - wave basis method for electronic structure calculations, for solving the corresponding eigenvalue problems. in addition, we propose two new modified parallel orbital - updating methods. compared to the traditional plane - wave methods, our methods allow for two - level parallelization, which is particularly interesting for large scale parallelization.   numerical experiments show that these new methods are more reliable and efficient for large scale calculations on modern supercomputers.   density functional theory, electronic structure, plane - wave, parallel orbital - updating.
we present the optical ( v, r, and i ) photometry for bl lacertae, which was observed from 1997 through 1999, with the 1.56-m telescope at the shanghai astronomical observatory ( shao ). after the 1997 outburst  , it dimmed to a low state and then brightened again. during the period jd 2450701 to jd 2450701.5, variations of 0.40mag, 0.27mag, and 0.21mag over a time scale of 100 minutes were found for v, r, and i bands, suggesting that the variations were decreasing with wavelength.   the correlation between v, r, and i is also analyzed using the dcf ( discrete correlation function ) method.   this shows that the variability in the v, r, and i bands are correlated with no time delay longer than 0.2 day.   galacxies : active ; bl lacertae objects : individual : bl lac ( pks 2200 + 420 ) ; galaxies : photometry
we consider a central system which is coupled via dephasing to an open system, i.e. an intermediate system which in turn is coupled to another environment. considering intermediate and far environment as one composite system,   the coherences in the central system are given in the form of fidelity amplitudes for a certain perturbed echo dynamics in the composite environment.   on the basis of the born - markov approximation, we derive a master equation for the reduction of that dynamics to the intermediate system alone. in distinction to an earlier paper  where we discussed the stabilizing effect of the far environment on the decoherence in the central system, we focus here on the possibility to use the measurable coherences in the central system for probing the open quantum dynamics in the intermediate system.   we illustrate our results for the case of chaotic dynamics in the near environment, where we compare random matrix simulations with our analytical result.     ] keywords + + + + + + + +    quantum loschmidt echo, fidelity, open quantum system, master equation, random matrix theory
the transition metal dichalcogenide ( tmd ) @xmath0-tas@xmath1 exhibits a rich set of charge density wave ( cdw ) orders.   recent investigations suggested that using light or electric field can manipulate the commensurate ( c ) cdw ground state.   such manipulations are considered to be determined by the charge carrier doping. here   we simulate by first - principles calculations the carrier doping effect on ccdw in @xmath0-tas@xmath1.   we investigate the charge doping effects on the electronic structures and phonon instabilities of @xmath0 structure and analyze the doping induced energy and distortion ratio variations in ccdw structure.   we found that both in bulk and monolayer @xmath0-tas@xmath1, ccdw is stable upon electron doping, while hole doping can significantly suppress the ccdw, implying different mechanisms of such reported manipulations.   light or positive perpendicular electric field induced hole doping increases the energy of ccdw, so that the system transforms to nccdw or similar metastable state. on the other hand,   even the ccdw distortion is more stable upon in - plain electric field induced electron injection, some accompanied effects can drive the system to cross over the energy barrier from ccdw to nearly commensurate ( nc ) cdw or similar metastable state.   we also estimate that hole doping can introduce potential superconductivity with @xmath2 of @xmath3 k. controllable switching of different states such as ccdw / mott insulating state, metallic state, and even the superconducting state can be realized in @xmath0-tas@xmath1, which makes the novel material have very promising applications in the future electronic devices.
the in - medium properties of the vector mesons are known to be modified significantly in hot and dense hadronic matter due to vacuum polarisation effects from the baryon sector in the walecka model.   the vector meson mass drops significantly in the medium due to the effects of the dirac sea. in the variational approach adopted in the present paper,   these effects are taken into account through a realignment of the ground state with baryon condensates.   such a realignment of the ground state becomes equivalent to summing of the baryonic tadpole diagrams in the relativistic hartree approximation ( rha ).   the approximation scheme adopted here goes beyond rha to include quantum effects from the scalar meson and is nonperturbative and self  consistent.   it includes multiloop effects, thus corresponding to a different approximation as compared to the one loop approximation of including scalar field quantum corrections. in the present work,   we study the properties of the vector mesons in the hot and dense matter as modified due to such quantum correction effects from the baryon as well as scalar meson sectors.   these medium modifications of the properties of the vector mesons are reflected, through the shifting and broadening of the respective peaks, in the low mass dilepton spectra.   there is broadening of the peaks due to corrections from scalar meson quantum effects as compared to the relativistic hartree approximation.   it is seen to be rather prominent for the @xmath0 meson in the invariant mass plot.   # 1
quantum electrodynamics  under conditions of distinguishability of interacting matter entities, and of controlled actions and back - actions between them, is considered.   such `` mesoscopic quantum electrodynamics '' is shown to share its dynamical structure with the classical stochastic electrodynamics. in formal terms, we demonstrate that all general relations of the mesoscopic quantum electrodynamics  may be recast in a form lacking planck s constant.   mesoscopic quantum electrodynamics  is therefore subject to `` doing quantum electrodynamics  while thinking classically '', allowing one to substitute essentally classical considerations for quantum ones without any loss in generality.   implications of these results for the quantum measurement theory are discussed.
we have developed a timing analysis method to determine the distances of variable galactic x - ray sources based on the method advanced by trmper and schnfelder in 1973.   the light - curve of the halo produced by the scattering of x - rays off the interstellar dust is delayed and smeared by the dust grains.   this method utilizes the differences between the power density spectra of the point source and the halo.   we present the details of this method and our first applications of this method to the chandra data of x - ray binary cyg x-3.   x - ray source distance, ism, scattering
ab initio results for structural and electronic properties of nacl - type fen are presented.   calculations are performed within a plane - wave and ultrasoft pseudopotential framework.   competition among paramagnetic, ferromagnetic and some possible antiferromagnetic phases is examined.   we find the ferromagnetic phase stable overall as observed.   stabilization over the unpolarized phase is obtained by splitting one flat @xmath0-type band crossing the fermi energy.   comparison with crn reveals that the magnetic ordering of crn, which consists of double - ferromagnetic sheets compensating along the  direction of the cubic cell and stabilized by the distortion of the squared symmetry on ( 100 ) plane, is not effective for fen.   the different behavior of fen and crn can be traced back to the smaller ionicity and magnetization of the former.
the compositions of nascent planets depend on the compositions of their birth disks.   in particular, the elemental compositions of gas giant gaseous envelopes depend on the elemental composition of the disk gas from which the envelope is accreted.   previous models demonstrated that sequential freeze - out of o and c - bearing volatiles in disks will result in an supersolar c / o ratios and subsolar c / h ratios in the gas between water and co snowlines.   this result does not take into account, however, the expected grain growth and radial drift of pebbles in disks, and the accompanying re - distribution of volatiles from the outer to the inner disk. using a toy model   we demonstrate that when drift is considered, co is enhanced between the water and co snowline, resulting in both supersolar c / o and c / h ratios in the disk gas in the gas giant formation zone.   this result appears robust to the details of the disk model as long as there is substantial pebble drift across the co snowline, and the efficiency of co vapor diffusion is limited.   gas giants that accrete their gaseous envelopes exterior to the water snowline and do not experience substantial core - envelope mixing, may thus present both superstellar c / o and c / h ratios in their atmospheres.   pebble drift will also affect the nitrogen and noble gas abundances in the planet forming zones, which may explain some of jupiter s peculiar abundance patterns.
evolutionary @xmath0 games are studied with players located on a square lattice. during the evolution   the randomly chosen neighboring players try to maximize their collective income by adopting a random strategy pair with a probability dependent on the difference of their summed payoffs between the final and initial state assuming quenched strategies in their neighborhood. in the case of the anti - coordination game   this system behaves alike an anti - ferromagnetic kinetic ising model. within a wide region of social dilemmas   this dynamical rule supports the formation of similar spatial arrangement of the cooperators and defectors ensuring the optimum total payoff if the temptation to choose defection exceeds a threshold value dependent on the sucker s payoff.   the comparison of the results with those achieved for pairwise imitation and myopic strategy updates has indicated the relevant advantage of pairwise collective strategy update in the maintenance of cooperation.
bp psc is a remarkable emission - line field star that is orbited by a dusty disk and drives a parsec - scale system of jets.   we report the detection by the _   chandra _ x - ray observatory of a weak x - ray point source coincident with the centroids of optical / ir and submillimeter continuum emission at bp psc. as the star s photosphere is obscured throughout the visible and near - infrared, the _ chandra _ x - ray source likely represents the first detection of bp psc itself.   the x - rays most likely originate with magnetic activity at bp psc and hence can be attributed either to a stellar corona or to star - disk interactions.   the log of the ratio of x - ray to bolometric luminosity, @xmath0, lies in the range @xmath1 to @xmath2.   this is smaller than @xmath0 ratios typical of low - mass, pre - main sequence stars, but is well within the @xmath0 range observed for rapidly - rotating ( fk com - type ) g giant stars.   hence, the _ chandra _ results favor an exotic model wherein the disk / jet system of bp psc is the result of its very recently engulfing a companion star or giant planet, as the primary star ascended the giant branch.
we overview the status of the studies on neutrino oscillations with accelerators at the present running experiments.   past and present results enlighten the path towards the observation of massive neutrinos and the settling of their oscillations.   the very near future may still have addiction from the outcome of the on - going experiments.   opera is chosen as a relevant example justified by the very recent results released.
we have observed the radio - quiet x - ray pulsar 1e  1207.45209 with the high throughput epic cameras onboard xmm - newton.   the spectrum of this peculiar source is characterized by two broad absorption features which present significant substructures and show a clear phase - dependence.   we believe that these features represent a strong evidence for the presence of a magnetized atmosphere containing heavy elements.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study the relation between @xmath0-helix formation and folding for a simple artificial peptide, ala@xmath1-gly@xmath2-ala@xmath1.   our data rely on multicanonical monte carlo simulations where the interactions among all atoms are taken into account.   the free - energy landscape of the peptide is evaluated for various temperatures.   our data indicate that folding of this peptide is a two - step process : in a first step two @xmath0-helices are formed which afterwards re - arrange themselves into a u - like structure.   = 1.6 cm
the observations of the total electronic component and the positron fraction in cosmic rays by the fermi, hess, atic, and pamela instruments are studied with analytical propagation models, both for a set of discrete sources and for a spatially smooth source distribution. the positron fraction over the entire energy range of @xmath0   is shown to fit with the nested leaky box model.   we derive the spectrum of electrons in cosmic rays arising from direct acceleration by the sources and discuss the narrow spectral feature in the spectrum.   electrons, positrons, dark matter
the conditions that lead to self - regulated star formation, star bursts and the formation of massive stellar clusters are discussed.   massive stars have a strong impact on their environment, especially on the evolution of dwarf galaxies which are the building blocks of giant galaxies.   energy input by massive young clusters might help to solve some of the most important puzzles of galaxy formation : the cosmological substructure problem and the angular momentum problem.
we present observations that were carried out with the two hundred micron photometer ( thumper ) mounted on the james clerk maxwell telescope ( jcmt ) in hawaii, at a wavelength of 200  @xmath0 m ( frequency 1.5  thz ).   the observations utilise a small atmospheric window that opens up at this wavelength under very dry conditions at high - altitude observing sites.   the atmosphere was calibrated using the sky - dipping method and a relation was established between the optical depth, @xmath1, at 1.5  thz and that at 225  ghz : @xmath2. mars and jupiter were mapped from the ground at this wavelength for the first time, and the system characteristics measured.   a noise equivalent flux density ( nefd ) of @xmath365@xmath410  jy ( 1@xmath5 1s ) was measured for the thumper   jcmt combination, consistent with predictions based upon our laboratory measurements.   the main - beam resolution of 14  arcsec was confirmed and an extended error - beam detected at roughly two - thirds of the magnitude of the main beam.   measurements of the sun allow us to estimate that the fraction of the power in the main beam is @xmath315%, consistent with predictions based on modelling the dish surface accuracy.   it is therefore shown that the sky over mauna kea is suitable for astronomy at this wavelength under the best conditions. however  , higher or drier sites should have a larger number of useable nights per year.       instrumentation : photometers  techniques : photometric  infrared : solar system  submillimetre
we use the clump giants of the disk as standard candles calibrated from hipparcos parallaxes in order to map their distribution with two new near - ir surveys of the galactic plane : ukidss - gps and vvv.   we explore different selection cuts of clump giants.   we conclude that there is an edge of the stellar disk of the milky way at @xmath0 kpc along various lines of sight across the galaxy.   the effect of the warp is considered, taking fields at different longitudes and above and below the plane.   we demonstrate that the edge of the stellar disk of the milky way can now be mapped in the near infrared in order to test different models, and to establish our own place within the galaxy.
a recent supernova has been reported as exceeding `` the light output of an ordinary supernova by at least two orders of magnitude ''. it is noted that it falls in a minor galaxy in the perseus cluster.   some evidence indicating a ten times closer distance for the perseus cluster than its redshift distance is discussed here.
we have detected an x - ray flare on the very low mass star vb 10 ( gl 752 b ; m8 v ) using the rosat high resolution imager.   vb 10 is the latest type ( lowest mass ) main sequence star known to exhibit coronal activity.   x - rays were detected from the star during a single 1.1-ksec segment of an observation which lasted 22 ksec in total.   the energy released by this flare is on the order of @xmath0 ergs s@xmath1.   this is at least two orders of magnitude greater than the quiescent x - ray luminosity of vb 10, which has yet to be measured.   this x - ray flare is very similar in nature to the far ultraviolet flare which was observed by linsky et al.   ( 1995 ) using the goddard high resolution spectrograph onboard the hubble space telescope.   we discuss reasons for the extreme difference between the flare and quiescent x - ray luminosities, including the possibility that vb 10 has no quiescent ( @xmath2 k ) coronal plasma at all.
the australia telescope compact array ( atca ) has been used to map class  i methanol masers at 36 and 44  ghz in g309.38@xmath00.13.   maser spots are found at nine locations in an area of 50@xmath130, with both transitions reliably detected at only two locations.   the brightest spot is associated with shocked gas traced by 4.5-@xmath2 m emission.   the data allowed us to make a serendipitous discovery of a high - velocity 36-ghz spectral feature, which is blue - shifted by about 30  km  s@xmath3 from the peak velocity at this frequency, but spatially located close to ( within a few arcseconds of ) the brightest maser spot.   we interpret this as indicating an outflow parallel to the line of sight.   such a high velocity spread of maser features, which has not been previously reported in the class  i methanol masers associated with a single molecular cloud, suggests that the outflow most likely interacts with a moving parcel of gas.       masers  ism : molecules  ism : jets and outflows
compact objects with a light sphere such as black holes and wormholes can reflect light rays like a mirror.   this gravitational lensing phenomenon is called retrolensing and it is an interesting tool to survey dark and compact objects with a light sphere near the solar system. in this paper, we calculate the deflection angle in the strong deflection limit analytically in the reissner - nordstrm spacetime without the expansion in power of the electrical charge. using the obtained deflection angle in the strong deflection limit, we investigate a retrolensing light curve and the separation of a double image by the light sphere of a reissner - nordstrm black hole.
in the nuclear and particle astrophysics session of cipanp 2003 we heard talks on a number of topics, focused for the most part into four broad areas. here   we outline the discussions of the standard cosmological model, dark matter searches, cosmic rays, and neutrino astrophysics.   the robustness of theoretical and experimental programs in all of these areas is very encouraging, and we expect to have many questions answered, and new ones asked, in time for cipanp 2006.   address = iscap, columbia astrophysics laboratory, mc 5247, 550 w 120th st.  , new york, ny 10027, altaddress = kipac, slac, m / s 78, 2575 sand hill rd., menlo park, ca 94025 ( from sept.  2003 )     address = physics department, boston university, room 255, 590 commonwealth ave.,   boston, ma 02215
historically, ge has been considered as a neutron - capture element. in this case, the r - process abundance of ge is derived through subtracting the s - process abundance from total abundance of the solar system. however,   the ge abundance of the metal - poor star hd 108317 is lower than that of the scaled  residual r - process abundance " in the solar system about 1.2 dex. in this work, based on the comparison between the ge abundances of the metal - poor star and stellar yields  , we find that the ge abundances would not be produced as the primary - like yields in the massive stars and mainly come from the r - process.   based on the observed abundances of metal - poor stars, we derived the ge abundances of the weak r - process and main r - process.   the contributed percentages of neutron - capture process to ge in the solar system are about 59%, which means that the contributed percentage of ge  residual abundance " in solar system is about 41%.   we find that the geresidual abundance " would be produced as the secondary - like yields in the massive stars.   this implies that ge element in the solar system is not only produced by the neutron - capture process.       nucleosynthesis, abundances - stars : abundances - stars : metal poor - element : germmanium
we present numerical results for pure @xmath0 yang - mills theory in four space - time dimensions using a novel algorithm based on dually transformed variables.   the simulation makes use of a recently derived @xmath1 algorithm for the dual vertex amplitude and a dual metropolis algorithm that generalizes the one recently developed for three dimensions.   the dual algorithm is validated against the equivalent model using conventional variables over a range of couplings, spin cut - offs, and lattice sizes.   we consider a lattice size up to @xmath2, where the problem of negative amplitudes renders the simulation results excessively noisy even at a relatively low @xmath3 ( starting at about @xmath4 ). in conclusion, we survey some approaches to addressing the sign problem and increasing the efficiency of dual computations.   @xmath5department of mathematics, university of western ontario, london, ontario, canada
we propose here a first - principles, parameter free, real space method for the study of disordered extended defects in solids.   we shall illustrate the power of the technique with an application to graphene sheets with randomly placed stone - wales defects and shall examine the signature of such random defects on the density of states as a function of their concentration.   the technique is general enough to be applied to a whole class of systems with lattice translational symmetry broken not only locally but by extended defects and defect clusters.   the real space approach will allow us to distinguish signatures of specific defects and defect clusters.   * h * # 1    extended disordered defects, real space recursion method
we report on x - ray and soft @xmath0-ray observations of the black - hole candidate  during its 2007 outburst, performed with the  and  satellites.   the hardness - intensity diagram of all /pca data combined shows a _ q_-shaped track similar to that observed in previous outbursts.the evolution in the diagram suggested that a transition from hard - intermediate state to soft - intermediate state occurred, simultaneously with  observations performed in march.   the transition is confirmed by the timing analysis presented in this work, which reveals that a weak type - a quasi - periodic oscillation ( qpo ) replaces a strong type - c qpo. at the same time, spectral analysis shows that the flux of the high - energy component shows a significant decrease in its flux.   however, we observe a delay ( roughly one day ) between variations of the spectral parameters of the high - energy component and changes in the flux and timing properties.   the changes in the high - energy component can be explained either in terms the high - energy cut - off or in terms of a variations in the reflection component.   we compare our results with those from a similar transition during the 2004 outburst of.       x - ray : binaries  accretion : accretion discs  black hole : physics  stars : individual :
ngc5905 is one of the very few galaxies that underwent a giant x - ray outburst, with a change in photon countrate of a factor @xmath0100.   the outburst spectrum is both, very soft and luminous ( bade, komossa & dahlem 1996 ).   our high - resolution follow - up optical spectroscopy of ngc5905 does not reveal any signs of seyfert activity. at present, this makes ngc 5905 the _ only _ non - active galaxy among the x - ray outbursting ones.   we discuss several scenarios to account for the exceptional properties of ngc5905, including a supernova in dense medium, an accretion - disk instability, an event of extreme gravitational lensing, and the x - ray afterglow of a grb to account for the x - ray outburst.   we find that the most likely model to explain the observations seems to be tidal disruption of a star by a central smbh, a scenario proposed by rees ( 1988 ) as a tracer of smbhs in nearby non - active galaxies.   the x - ray outburst in this hii galaxy then lends further support to the scenario that _ all _ galaxies passed through an active phase, leaving unfed smbhs in their centers.
evolutionary algorithms have been widely studied from a theoretical perspective. in particular, the area of runtime analysis   has contributed significantly to a theoretical understanding and provided insights into the working behaviour of these algorithms.   we study how these insights into evolutionary processes can be used for evolutionary art.   we introduce the notion of evolutionary image transition which transfers a given starting image into a target image through an evolutionary process. combining standard mutation effects known from the optimization of the classical benchmark function onemax and different variants of random walks, we present ways of performing evolutionary image transition with different artistic effects.
quantum vacuum forces dictate the interaction between individual atoms and dielectric surfaces at nanoscale distances.   for example, their large strengths typically overwhelm externally applied forces, which makes it challenging to controllably interface cold atoms with nearby nanophotonic systems. here  , we show that it is possible to tailor the vacuum forces themselves to provide strong trapping potentials.   the trapping scheme takes advantage of the attractive ground state potential and adiabatic dressing with an excited state whose potential is engineered to be resonantly enhanced and repulsive.   this procedure yields a strong metastable trap, with the fraction of excited state population scaling inversely with the quality factor of the resonance of the dielectric structure.   we analyze realistic limitations to the trap lifetime and discuss possible applications that might emerge from the large trap depths and nanoscale confinement.
effective slam using a single monocular camera is highly preferred due to its simplicity. however, when compared to trajectory planning methods using depth - based slam, monocular slam in loop does need additional considerations.   one main reason being that for the optimization, in the form of bundle adjustment ( ba ), to be robust, the slam system needs to scan the area for a reasonable duration.   most monocular slam systems do not tolerate large camera rotations between successive views and tend to breakdown.   other reasons for monocular slam failure include ambiguities in decomposition of the essential matrix, feature - sparse scenes and more layers of non linear optimization apart from ba.   this paper presents a novel formulation based on reinforcement learning ( rl ) that generates fail safe trajectories wherein the slam generated outputs ( scene structure and camera motion ) do not deviate largely from their true values.   quintessentially, the rl framework successfully learns the otherwise complex relation between motor actions and perceptual inputs that result in trajectories that do not cause failure of slam, which are almost intractable to capture in an obvious mathematical formulation.   we show systematically in simulations how the quality of the slam map and trajectory dramatically improves when trajectories are computed by using rl.
we present suzaku x - ray observations of the recurrent nova t crb in quiescence.   t crb is the first recurrent nova to be detected in the hard - x - ray band ( @xmath0 kev ) during quiescence.   the x - ray spectrum is consistent with cooling - flow emission emanating from an optically thin region in the boundary layer of an accretion disk around the white dwarf.   the detection of strong stochastic flux variations in the light curve supports the interpretation of the hard x - ray emission as emanating from a boundary layer.
evidence is emerging that the luminous x - ray sources in the cores of globular clusters may often consist of, or perhaps even as a class be dominated by, ultracompact ( p1  hr ) binary stars.   to the two such systems already known, in ngc6624 and ngc6712, we now add evidence for two more.   we detect large amplitude variability in the candidate optical counterpart for the x - ray source in the core of ngc6652.   although the available observations are relatively brief, the existing _ hubble space telescope _ data indicate a strong 43.6  min periodic modulation of the visible flux of semi - amplitude 30%.   further, although the orbital period of the source in ngc1851 is not yet explicitly measured, we demonstrate that previous correlations of optical luminosity with x - ray luminosity and accretion disk size, strengthened by recent data, strongly imply that the period of that system is also less than 1  hr.   thus currently there is evidence that 4 of the 7 globular cluster x - ray sources with constrained periods are ultracompact, a fraction far greater than that found in x - ray binaries the field.   -0.5 in 9.20 in    0.216 in    accepted for publication in the astrophysical journal letters + _ received 1999 november 5 ; accepted 1999 december 13 _
we analyze spatially resolved spectroscopic observations of the eta carinae binary system obtained with hst / stis.   eta car is enshrouded by the dusty homunculus nebula, which scatters light emitted by the central binary and provides a unique opportunity to study a massive binary system from different vantage points.   we investigate the latitudinal and azimuthal dependence of h@xmath0 line profiles caused by the presence of a wind - wind collision ( wwc ) cavity created by the companion star. using two - dimensional radiative transfer models,   we find that the wind cavity can qualitatively explain the observed line profiles around apastron. regions of the homunculus which scatter light that propagated through the wwc cavity show weaker or no h@xmath0 absorption.   regions scattering light that propagated through a significant portion of the primary wind show stronger p cygni absorption.   our models overestimate the h@xmath0 absorption formed in the primary wind, which we attribute to photoionization by the companion, not presently included in the models.   we can qualitatively explain the latitudinal changes that occur during periastron, shedding light on the nature of eta car s spectroscopic events.   our models support the idea that during the brief period of time around periastron when the primary wind flows unimpeded toward the observer, h@xmath0 absorption occurs in directions toward the central object and homunculus se pole, but not toward equatorial regions close to the weigelt blobs.   we suggest that observed latitudinal and azimuthal variations are dominated by the companion star via the wwc cavity, rather than by rapid rotation of the primary star.
in this paper we develop a quantum field approach to reveal the thermodynamic properties of the trapped bec with the equal rashba and dresselhaus spin - orbit couplings. in the experimentally - feasible regime, the phase transition from the separate phase to the single minimum phase can be well driven by the tunable temperature. moreover, the critical temperature, which is independent of the trapped potential, can be derived exactly. at the critical point  , the specific heat has a large jump and can be thus regarded as a promising candidate to detect this temperature - driven phase transition.   in addition, we obtain the analytical expressions for the specific heat and the entropy in the different phases. in the single minimum phase,   the specific heat as well as the entropy are governed only by the rabi frequency. however, in the separate phase with lower temperature, we find that they are determined only by the strength of spin - orbit coupling. finally, the effect of the effective atom interaction is also addressed. in the separate phase, this effective atom interaction affects dramatically on the critical temperature and the corresponding thermodynamic properties.
a system of two masses connected with a weightless rod ( called dumbbell in this paper ) interacting with a flat boundary is considered.   the sharp bound on the number of collisions with the boundary is found using billiard techniques. in case, the ratio of masses is large and the dumbbell rotates fast, an adiabatic invariant is obtained.
we propose a method to perform precision measurements of the interaction parameters in systems of @xmath0 ultra - cold spin @xmath1 atoms.   the spectroscopy is realized by first creating a coherent spin superposition of the two relevant internal states of each atom and then letting the atoms evolve under a squeezing hamiltonian.   the non - linear nature of the hamiltonian decreases the fundamental limit imposed by the heisenberg uncertainty principle to @xmath2, a factor of @xmath0 smaller than the fundamental limit achievable with non - interacting atoms.   we study the effect of decoherence and show that even with decoherence, entangled states can outperform the signal to noise limit of non - entangled states.   we present two possible experimental implementations of the method using bose - einstein spinor condensates and fermionic atoms loaded in optical lattices and discuss their advantages and disadvantages.
the period - metallicity - k band luminosity ( pl@xmath0 ) relation for rr lyrae stars in 15 galactic globular clusters and in the lmc globular cluster reticulum has been derived.   it is based on accurate near infrared ( k ) photometry combined with 2mass and other literature data. the pl@xmath0 relation has been calibrated and compared with the previous empirical and theoretical determinations in literature.   the zero point of the absolute calibration has been obtained from the k magnitude of rr lyr whose distance modulus has been measured via trigonometric parallax with hst. using this relation   we obtain a distance modulus to the lmc of @xmath1 mag, in good agreement with recent determinations based on the analysis of cepheid variable stars.       methods : observational  techniques : photometric  stars : distances  stars : variables : rr lyrae  infrared : stars
the fairness of ieee 802.11 wireless networks ( including wireless lan and ad - hoc networks ) is hard to predict and control because of the randomness and complexity of the mac contentions and dynamics.   moreover, asymmetric channel conditions such as those caused by capture and channel errors often lead to severe unfairness among stations. in this paper   we propose a novel distributed scheduling algorithm that we call vls, for `` _ variable - length scheduling _ '', that provides weighted fairness to all stations despite the imperfections of the mac layer and physical channels.   distinct features of vls include the use of variable transmission lengths based on distributed observations, compatibility with 802.11 s contention window algorithm, opportunistic scheduling to achieve high throughput in time - varying wireless environments, and flexibility and ease of implementation.   also, vls makes the throughput of each station more smooth, which is appealing to real - time applications such as video and voice.   although the paper mostly assumes 802.11 protocol, the idea generally applies to wireless networks based on csma ( carrier sensing multiple access )  .    distributed fair scheduling, variable transmission lengths, carrier sensing multiple access, ieee 802.11, wireless channel
early data taken during commissioning of the sdss have resulted in the discovery of a very cool white dwarf.   it appears to have stronger collision induced absorption from molecular hydrogen than any other known white dwarf, suggesting it has a cooler temperature than any other.   while its distance is presently unknown, it has a surprisingly small proper motion, making it unlikely to be a halo star.   an analysis of white dwarf cooling times suggests that this object may be a low - mass star with a helium core.   the sdss imaging and spectroscopy also recovered lhs  3250, the coolest previously known white dwarf, indicating that the sdss will be an effective tool for identifying these extreme objects.
we use the quasiparticle random phase approximation with a few skyrme density functionals to calculate strength functions in the @xmath0 and @xmath1 channels for even ca, ni, and sn isotopes, from the proton drip line to the neutron drip line.   we show where and how low - lying strength begins to appear as @xmath2 increases.   we also exhibit partial energy - weighted sums of the transition strength as functions of @xmath2 for all nuclei calculated, and transition densities for many of the interesting peaks.   we find that low - energy strength increases with @xmath2 in all multipoles, but with distinctive features in each.   the low - lying @xmath3 strength near the neutron at large @xmath2 barely involves protons at all, with the strength coming primarily from a single two - quasineutron configuration with very large spatial extent.   the low - lying @xmath4 strength is different, with protons contributing to the transition density in the nuclear interior together with neutrons at large radii.   the low - lying @xmath1 transition strength goes largely to more localized states.   the three skyrme interactions we test produce similar results, differing most significantly in their predictions for the location of the neutron drip line, the boundaries of deformed regions, energies of and transition strengths to the lowest @xmath1 states between closed shells, and isovector energy - weighted sum rules.
sequence a000975 in the online encyclopedia of integer sequences ( oeis ) starts out 1, 2, 5, 10, 21, 42, 85,  .   as of july 1, 2016, the description in the oeis lists several characterizations of this sequence and numerous examples of instances where this sequence occurs.   it also presents a `` not yet proved '' result, a conjecture, and an unanswered question concerning this sequence. in this paper   we show that all of these proposed results are in fact true.
these lectures provide an introduction to the subject of tachyon condensation in the open bosonic string.   the problem of tachyon condensation is first described in the context of the low - energy yang - mills description of a system of multiple d - branes, and then using the language of string field theory.   an introduction is given to witten s cubic open bosonic string field theory.   the sen conjectures on tachyon condensation in open bosonic string field theory are introduced, and evidence confirming these conjectures is reviewed.   mit - ctp-3341 + hep - th/0301094    * lectures on d - branes, tachyon condensation, and string field theory + *    notes on lectures presented at the cecs school on quantum gravity, + valdivia, chile, january 2002    washington taylor     + _ mit, bldg.   6 - 308 _ + _ cambridge, ma 02139, u.s.a.   _ + wati@mit.edu   +    november 2002
we revisit the results of recent electroweak baryogenesis calculations and include all allowed large cp - violating supersymmetric phases.   if the phases are large, the resulting baryon asymmetry can be considerably larger than the observed value @xmath0.   much of the asymmetry must therefore be washed out, and we argue that the upper bound on the light higgs mass is larger than the value reported in previous work.   # 1#1 # 1(#1 )
recently the most general static self - consistent multi - soliton solutions in bogoliubov - de gennes and chiral gross - neveu systems are derived by the present authors [ d. a. takahashi and m. nitta, phys.   rev.   lett. * 110 *, 131601 ( 2013 ) ]. here   we show a few complementary results, which were absent in the previous our work.   we prove _ directly from the gap equation _ that the self - consistent solutions need to have reflectionless potentials.   we also give the self - consistent condition for the system consisting of only right - movers, which is more used in high - energy physics.   pacs numbers : 03.75.ss, 67.85.-d, 74.20.-z, 11.10.kk
the atlas pixel detector is the innermost detector of the atlas experiment at the large hadron collider at cern. with approximately 80 million readout channels,   the atlas silicon pixel detector is a high - acceptance, high - resolution, low - noise tracking device. providing the desired refinement in charged track pattern recognition capability in order to meet the stringent track reconstruction requirements,   the pixel detector largely defines the ability of atlas to effectively resolve primary and secondary vertices and perform efficient flavor tagging essential for discovery of new physics.   being the last sub - system installed in atlas by july 2007, the pixel detector was successfully connected, commissioned, and tested _ in situ _ while meeting an extremely tight schedule, and was ready to take data upon the projected turn - on of the lhc. since fall 2008  , the pixel detector has been included in the combined atlas detector operation, collecting cosmic muon data.   details from the pixel detector installation and commissioning, as well as details on calibration procedures and the results obtained with collected cosmic data, are presented along with a summary of the detector status.
high - resolution x - ray spectroscopy has addressed not only various topics in coronal physics of stars, but has also uncovered important features relevant for our understanding of stellar evolution and the stellar environment.   i summarize recent progress in coronal x - ray spectroscopy and in particular also discuss new results from studies of x - rays from pre - main sequence stars.
a path relinking algorithm is proposed for the bandwidth coloring problem and the bandwidth multicoloring problem.   it combines a population based relinking method and a tabu search based local search procedure.   the proposed algorithm is assessed on two sets of 66 benchmark instances commonly used in the literature.   computational results demonstrate that the proposed algorithm is highly competitive in terms of both solution quality and efficiency compared to the best performing algorithms in the literature.   specifically, it improves the previous best known results for 15 out of 66 instances, while matching the previous best known results for 47 cases.   some key elements of the proposed algorithm are investigated.   + _ keywords _ : bandwidth coloring, path relinking, tabu search, heuristics, frequency assignment.
graphene outstanding properties directly come from its pecular electronic structure and thus from the honeycomb lattice symmetry.   the way interaction with the substrate impact this lattice is of primary importance.   this is peculiarly true for epitaxial graphene because of the sic substrate.   the advantage of this system that produces macroscopic samples in registry with a substrate could turn to a major drawback if the graphene lattice reveals to be strongly distorted.   extensive ab initio calculations supported by scanning tunneling microscopy experiments, demonstrate here that the substrate indeed induces a strong nanostructuration of the interface carbon layer.   it propagates to the above c layer where it generates incommensurate ripples in the honeycomb lattice.
we estimate the contribution of extragalactic radio sources to fluctuations in sky temperature over the range of frequencies ( 10 - 300 ghz ) used for cosmic microwave background ( cmb ) anisotropy measurements.   cmb anisotropy observations at high resolution and low frequencies are especially sensitive to this foreground. we have compiled a catalog of 2207 bright radio sources, including 758 sources with flux measurements at 90 ghz.   we develop a method to extrapolate the source spectra and predict skymaps of extragalactic radio sources at instrument resolutions of @xmath0 fwhm.   our results indicate that the brightest radio sources will dominate microwave anisotropy for a wide range of resolutions and frequencies.   our skymaps predict the location and flux of the brightest radio sources at each frequency, making it straightforward to develop a template for masking the pixels containing them.   this masking should be sufficient to protect high resolution cmb anisotropy observations from unacceptable radio source confusion.   epsf.sty    submitted to the _ astrophysical journal _
the formation of secondary structures by a random rna sequence is studied as a model system for the sequence - structure problem omnipresent in biopolymers.   several toy energy models are introduced to allow detailed analytical and numerical studies.   first, a two - replica calculation is performed. by mapping the two - replica problem to the denaturation of a single homogeneous rna in @xmath0-dimensional embedding space,   we show that sequence disorder is perturbatively irrelevant, i.e., an rna molecule with weak sequence disorder is in a _ molten phase _ where many secondary structures with comparable total energy coexist.   a numerical study of various models at high temperature reproduces behaviors characteristic of the molten phase. on the other hand, a scaling argument based on the extremal statistics of rare regions   can be constructed to show that the low temperature phase is unstable to sequence disorder.   we performed a detailed numerical study of the low temperature phase using the droplet theory as a guide, and characterized the statistics of large - scale, low - energy excitations of the secondary structures from the ground state structure.   we find the excitation energy to grow very slowly ( i.e., logarithmically ) with the length scale of the excitation, suggesting the existence of a marginal glass phase.   the transition between the low temperature glass phase and the high temperature molten phase is also characterized numerically.   it is revealed by a change in the coefficient of the logarithmic excitation energy, from being disorder dominated to entropy dominated.
we study the interaction of gaussian one- and two - photon pulses with a single two - level atom based on a one - dimensional model of pulse propagation to and from the atom.   the characteristic time scale of the atomic response is the dipole relaxation time @xmath0.   we therefore compare the effect of the non - linear two - photon interaction for a long pulse length of @xmath1 with a short pulse of @xmath0.   our results indicate that the effect of the non - linear interaction is particularly strong for the short pulse length of @xmath0.   +   +
first - generation ( population iii ) stars in the universe play an important role in early enrichment of heavy elements in galaxies and intergalactic medium and thus affect the history of galaxies.   the physical and chemical properties of primordial gas clouds are significantly different from those of present - day gas clouds observed in the nearby universe because the primordial gas clouds do not contain any heavy elements which are important coolants in the gas.   previous theoretical considerations have suggested that typical masses of the first - generation stars are between several @xmath0 and @xmath1 although it has been argued that the formation of very massive stars ( e.g., @xmath2 ) is also likely.   if stars with several @xmath0 are most popular ones at the epoch of galaxy formation, most stars will evolve to hot ( e.g., @xmath3 k ), luminous ( @xmath4 ) stars with gaseous and dusty envelope prior to going to die as white dwarf stars.   although the duration of this phase is short ( e.g., @xmath5 yr ), such evolved stars could contribute both to the ionization of gas in galaxies and to the production of a lot of dust grains if the formation of intermediate - mass stars is highly enhanced.   we compare gaseous emission - line properties of such nebulae with some interesting high - redshift galaxies such as iras f10214 + 4724 and powerful radio galaxies.
we examine a regime in which a linearly - polarized laser pulse with relativistic intensity irradiates a sub - critical plasma for much longer than the characteristic electron response time.   a steady - state channel is formed in the plasma in this case with quasi - static transverse and longitudinal electric fields.   these relatively weak fields significantly alter the electron dynamics.   the longitudinal electric field reduces the longitudinal dephasing between the electron and the wave, leading to an enhancement of the electron energy gain from the pulse. the energy gain in this regime   is ultimately limited by the superluminosity of the wave fronts induced by the plasma in the channel.   the transverse electric field alters the oscillations of the transverse electron velocity, allowing it to remain anti - parallel to laser electric field and leading to a significant energy gain.   the energy enhancement is accompanied by development of significant oscillations perpendicular to the plane of the driven motion, making trajectories of energetic electrons three - dimensional. proper electron injection into the laser beam can further boost the electron energy gain.
the safety of a quantum key distribution system relies on the fact that any eavesdropping attempt on the quantum channel creates errors in the transmission. for a given error rate,   the amount of information that may have leaked to the eavesdropper depends on both the particular system and the eavesdropping strategy. in this work,   we discuss quantum cryptographic protocols based on the transmission of weak coherent states and present a new system, based on a symbiosis of two existing ones, and for which the information available to the eavesdropper is significantly reduced.   this system is therefore safer than the two previous ones.   we also suggest a possible experimental implementation.
from the viewpoint of the formulation of the su(2 ) coherent states and their path integrals labeled by a full set of euler angles @xmath0 which we developed in the previous paper, we study the relations between gauge symmetries of lagrangians and allowed quantum states ; we investigate permissible types of fiducial vectors in the full quantum dynamics in terms of su(2 ) coherent states.   we propose a general framework for a lagrangian having a certain gauge symmetry with respect to one of the euler angles @xmath1.   we find that when a lagrangian has the gauge symmetry fiducial vectors are so restricted that they belong to the eigenstates of @xmath2 or to the orbits of them under the action of the su(2 ) ; and the strength of a fictitious monopole, which appears in the lagrangian, is a multiple of @xmath3. in this case dirac strings are permitted.   one exceptional case exists when the fictitious monopole charge disappears.   the reasoning here does not work for a lagrangian without the gauge symmetry.   the relations between formulations and results of the preceding work by stone that has piloted us and those by ours are also discussed.
we present theoretical studies of the influence of spin orbit coupling on the spin wave excitations of the fe monolayer and bilayer on the w(110 ) surface.   the dzyaloshinskii - moriya interaction is active in such films, by virtue of the absence of reflection symmetry in the plane of the film.   when the magnetization is in plane, this leads to a linear term in the spin wave dispersion relation for propagation across the magnetization.   the dispersion relation thus assumes a form similar to that of an energy band of an electron trapped on a semiconductor surfaces with rashba coupling active.   we also show speels response functions that illustrate the role of spin orbit coupling in such measurements.   in addition to the modifications of the dispersion relations for spin waves, the presence of spin orbit coupling in the w substrate leads to a substantial increase in the linewidth of the spin wave modes.   the formalism we have developed applies to a wide range of systems, and the particular system explored in the numerical calculations provides us with an illustration of phenomena which will be present in other ultrathin ferromagnet / substrate combinations.
we consider the x - ray luminosity difference between neutron star and black hole soft x - ray transients ( ns and bh sxts ) in quiescence.   the current observational data suggest that bh sxts are significantly fainter than ns sxts.   the luminosities of quiescent bh sxts are consistent with the predictions of binary evolution models for the mass transfer rate if ( 1 ) accretion occurs via an adaf in these systems and ( 2 ) the accreting compact objects have event horizons.   the luminosities of quiescent ns sxts are not consistent with the predictions of adaf models when combined with binary evolution models, unless most of the mass accreted in the adaf is prevented from reaching the neutron star surface.   we consider the possibility that mass accretion is reduced in quiescent ns sxts because of an efficient propeller and develop a model of the propeller effect that accounts for the observed luminosities.   we argue that modest winds from adafs are consistent with the observations, while strong winds are probably not.    #   1to 0pt#1
for random walks on networks ( graphs ), it is a theoretical challenge to explicitly determine the mean first - passage time ( mfpt ) between two nodes averaged over all pairs. in this paper  , we study the mfpt of random walks in the famous t - graph, linking this important quantity to the resistance distance in electronic networks.   we obtain an exact formula for the mfpt that is confirmed by extensive numerical calculations. the interesting quantity is derived through the recurrence relations resulting from the self - similar structure of the t - graph.   the obtained closed - form expression exhibits that the mfpt approximately increases as a power - law function of the number of nodes, with the exponent lying between 1 and 2.   our research may shed light on the deeper understanding of random walks on the t - graph.
the orbital structure of triaxial models with weak central density cusps, @xmath0, @xmath1, is investigated.   the stability of the @xmath2- ( long- ) axis orbit  and hence the existence of box orbits  depends sensitively on @xmath3 ; the range of model shapes for which the @xmath2-axis orbit is stable becomes progressively smaller as @xmath3 approaches one.   the banana and fish boxlets in the @xmath4 ( long axis  short axis ) plane are stable over a wide range of model parameters.   the boxlets in the @xmath5 and @xmath6 planes are generally vertically unstable.   # 1#23.6pt # 1#1
cells are constantly exposed to fluctuating environmental conditions.   external signals are sensed, processed and integrated by cellular signal transduction networks, which translate input signals into specific cellular responses by means of biochemical reactions.   these networks have a complex nature, and we are still far from having a complete characterization of the process through which they integrate information, specially given the noisy environment in which that information is embedded.   guided by the many instances of constructive influences of noise that have been reported in the physical sciences in the last decades, here we explore how multiple signals are integrated in an eukaryotic cell in the presence of background noise, or chatter. to that end  , we use a boolean model of a typical human signal transduction network. despite its complexity  , we find that the network is able to display simple patterns of signal integration.   furthermore, our computational analysis shows that these integration patterns depend on the levels of fluctuating background activity carried by other cell inputs. taken together,   our results indicate that signal integration is sensitive to environmental fluctuations, and that this background noise effectively determines the information integration capabilities of the cell.   signal integration, chatter, boolean network, logic gate, cellular noise
charge equilibration has been recognized as a dominant process at the early stage of low - energy heavy - ion reactions.   the production of exotic nuclei is suppressed under the appearance of charge equilibration, in which the proton - neutron ratios of the final reaction products are inevitably averaged.   therefore charge equilibration plays one of the most crucial roles in the synthesis of chemical elements.   focusing on how and when the charge equilibration takes place, the zero - sound propagation in femto - scale quantum liquids is explained.
protostellar jets and winds are probably driven magnetocentrifugally from the surface of accretion disks close to the central stellar objects.   the exact launching conditions on the disk, such as the distributions of magnetic flux and mass ejection rate, are poorly unknown.   they could be constrained from observations at large distances, provided that a robust model is available to link the observable properties of the jets and winds at the large distances to the conditions at the base of the flow.   we discuss the difficulties in constructing such large - scale wind models, and describe a novel technique which enables us to numerically follow the acceleration and propagation of the wind from the disk surface to arbitrarily large distances and the collimation of part of the wind into a dense, narrow `` jet '' around the rotation axis.   special attention is paid to the shape of the jet and its mass flux relative to that of the whole wind.   the mass flux ratio is a measure of the jet formation efficiency.
using the gauge - gravity duality, we argue that for a certain class of out - of - equilibrium steady - state systems in contact with a thermal background at a given temperature, the macroscopic physics can be captured by an effective thermodynamic description.   the steady - state is obtained by applying a constant electric field that results in a stationary current flow. within holography  , we consider generic probe systems where an open string equivalence principle and an open string metric govern the effective thermodynamics.   this description comes equipped with an effective temperature, which is larger than the background temperature, and a corresponding effective entropy. for conformal or scale - invariant theories, certain scaling behaviours follow immediately. in general, in the large electric field limit, this effective temperature is also observed to obey generic relations with various physical parameters in the system.
we present a study of spatial variations in the metallicity of old red giant branch stars in the andromeda galaxy.   photometric metallicity estimates are derived by interpolating isochrones for over seven million stars in the panchromatic hubble andromeda treasury ( phat ) survey.   this is the first systematic study of stellar metallicities over the inner 20  kpc of andromeda s galactic disk.   we see a clear metallicity gradient of @xmath0 dex / kpc from @xmath1 kpc assuming a constant rgb age.   this metallicity gradient is derived after correcting for the effects of photometric bias and completeness and dust extinction and is quite insensitive to these effects.   the unknown age gradient in m31 s disk creates the dominant systematic uncertainty in our derived metallicity gradient.   however, spectroscopic analyses of galaxies similar to m31 show that they typically have small age gradients that make this systematic error comparable to the 1@xmath2 error on our metallicity gradient measurement. in addition to the metallicity gradient, we observe an asymmetric local enhancement in metallicity at radii of 3 - 6  kpc that appears to be associated with andromeda s elongated bar.   this same region also appears to have an enhanced stellar density and velocity dispersion.
recent works on planetary migration show that the orbital structure of the kuiper belt can be very well reproduced if before the onset of the planetary instability neptune underwent a long - range planetesimal - driven migration up to @xmath028 au. however, considering that all giant planets should have been captured in mean motion resonances among themselves during the gas - disk phase, it is not clear whether such a very specific evolution for neptune is possible, nor whether the instability could have happened at late times. here,   we first investigate which initial resonant configuration of the giant planets can be compatible with neptune being extracted from the resonant chain and migrating to @xmath028 au before that the planetary instability happened.   we address the late instability issue by investigating the conditions where the planets can stay in resonance for about 400 my. our results indicate that this can happen only in the case where the planetesimal disk is beyond a specific minimum distance @xmath1 from neptune. then, if there is a sufficient amount of dust produced in the planetesimal disk, that drifts inwards, neptune can enter in a slow dust - driven migration phase for hundreds of mys until it reaches a critical distance @xmath2 from the disk. from that point,   faster planetesimal - driven migration takes over and neptune continues migrating outward until the instability happens.   we conclude that, although an early instability reproduces more easily the evolution of neptune required to explain the structure of the kuiper belt, such evolution is also compatible with a late instability.
folksonomies  large databases arising from collaborative tagging of items by independent users - are becoming an increasingly important way of categorizing information. in these systems   users can tag items with free words, resulting in a tripartite item - tag - user network.   although there are no prescribed relations between tags, the way users think about the different categories presumably has some built in hierarchy, in which more special concepts are descendants of some more general categories.   several applications would benefit from the knowledge of this hierarchy. here   we apply a recent method to check the differences and similarities of hierarchies resulting from tags given by independent individuals and from tags given by a centrally managed repository system.   the results from our method showed substantial differences between the lower part of the hierarchies, and in contrast, a relatively high similarity at the top of the hierarchies.   keywords : tag, hierarchy, ontology reconstruction, folksonomy, knowledge mapping
we study the plasma - induced modifications of the potential and charge distribution across the interface of a plasma and a dielectric wall. for this purpose, the wall - bound surplus charge arising from the plasma   is modelled as a quasi - stationary electron surface layer in thermal equilibrium with the wall.   it satisfies poisson s equation and minimizes the grand canonical potential of wall - thermalized excess electrons.   based on an effective model for a graded interface taking into account the image potential and the offset of the conduction band to the potential just outside the dielectric, we specifically calculate the modification of the potential and the distribution of the surplus electrons for mgo, sio@xmath0 and al@xmath0o@xmath1 surfaces in contact with a helium discharge. depending on the electron affinity of the surface, we find two vastly different behaviors. for negative electron affinity, electrons do not penetrate into the wall and a quasi - two - dimensional electron gas is formed in the image potential, while for positive electron affinity, electrons penetrate into the wall and a negative space charge layer develops in the interior of the dielectric.   we also investigate how the non - neutral electron surface layer  which can be understood as the ultimate boundary of a bounded gas discharge  merges with the neutral bulk of the dielectric.
sequences of experimental ground - state energies for both odd and even @xmath0 are mapped onto concave patterns cured from convexities due to pairing and/or shell effects.   the same patterns, completed by a list of excitation energies, give numerical estimates of the grand potential @xmath1 for a mixture of nuclei at low or moderate temperatures @xmath2 and at many chemical potentials @xmath3 the average nucleon number @xmath4 then becomes a continuous variable, allowing extrapolations towards nuclear masses closer to drip lines.   we study the possible concavity of several thermodynamical functions, such as the free energy and the average energy, as functions of @xmath5 concavity, which always occurs for the free energy and is usually present for the average energy, allows easy interpolations and extrapolations providing upper and lower bounds, respectively, to binding energies.   such bounds define an error bar for the prediction of binding energies.   finally we show how concavity and universality are related in the theory of the nuclear density functional.    *   pacs : * 21.10.dr, 21.10.-k, 21.60.-n, 24.10.pa
we propose new ergodic interference alignment techniques for @xmath0-user interference channels with delayed feedback.   two delayed feedback scenarios are considered  delayed channel information at transmitter ( cit ) and delayed output feedback.   it is proved that the proposed techniques achieve total @xmath1 dof which is higher than that by the retrospective interference alignment for for the delayed feedback scenarios.   interference channel, degrees of freedom ( dof ), ergodic interference alignment, delayed feedback.
in indirect resonant inelastic x - ray scattering ( rixs ) an intermediate state is created with a core - hole that has an ultrashort lifetime.   the core - hole potential therefore acts as a femtosecond pulse on the valence electrons.   we show that this fact can be exploited to integrate out the intermediate states from the expressions for the scattering cross section. by this   we obtain an effective scattering cross section that only contains the initial and final scattering states.   we derive in detail the effective cross section which turns out to be a resonant scattering factor times a linear combination of the charge response function @xmath0 and the dynamic longitudinal spin density correlation function.   this result is asymptotically exact for both strong and weak local core - hole potentials and ultrashort lifetimes.   the resonant scattering pre - factor is shown to be weakly temperature dependent.   we also derive a sum - rule for the total scattering intensity and generalize the results to multi - band systems.   one of the remarkable outcomes is that one can change the relative charge and spin contribution to the inelastic spectral weight by varying the incident photon energy.
we introduce a growing network model in which a new node attaches to a randomly - selected node, as well as to all ancestors of the target node.   this mechanism produces a sparse, ultra - small network where the average node degree grows logarithmically with network size while the network diameter equals 2.   we determine basic geometrical network properties, such as the size dependence of the number of links and the in- and out - degree distributions.   we also compare our predictions with real networks where the node degree also grows slowly with time  the internet and the citation network of all physical review papers.
we study several issues related to the different choices of time available for the classical and quantum treatment of linearly polarized cylindrical gravitational waves.   we pay especial attention to the time evolution of creation and annihilation operators and the definition of fock spaces for the different choices of time involved.   we discuss also the issue of microcausality and the use of field commutators to extract information about the causal properties of quantum spacetime.
we investigate the use of a logarithmic density variable in estimating the lagrangian displacement field, motivated by the success of a logarithmic transformation in restoring information to the matter power spectrum.   the logarithmic relation is an extension of the linear relation, motivated by the continuity equation, in which the density field is assumed to be proportional to the divergence of the displacement field ; we compare the linear and logarithmic relations by measuring both of these fields directly in a cosmological @xmath0-body simulation.   the relative success of the logarithmic and linear relations depends on the scale at which the density field is smoothed.   thus we explore several ways of measuring the density field, including cloud - in - cell smoothing, adaptive smoothing, and the ( scale - independent ) delaunay tessellation, and we use both a fourier space and a geometrical tessellation approach to measuring the divergence.   we find that the relation between the divergence of the displacement field and the density is significantly tighter with a logarithmic density variable, especially at low redshifts and for very small ( @xmath12 h@xmath2mpc ) smoothing scales.   we find that the grid - based methods are more reliable than the tessellation - based method of calculating both the density and the divergence fields, though in both cases the logarithmic relation works better in the appropriate regime, which corresponds to nonlinear scales for the grid - based methods and low densities for the tessellation - based method.
voting rules allow multiple agents to aggregate their preferences in order to reach joint decisions.   perhaps one of the most important desirable properties in this context is _ condorcet - consistency _, which requires that a voting rule should return an alternative that is preferred to any other alternative by some majority of voters.   another desirable property is _ participation _, which requires that no voter should be worse off by joining an electorate.   a seminal result in social choice theory by @xcite has shown that condorcet - consistency and participation are incompatible whenever there are at least  4 alternatives and  25 voters.   we leverage sat solving to obtain an elegant human - readable proof of moulin s result that requires only  12 voters.   moreover, the sat solver is able to construct a condorcet - consistent voting rule that satisfies participation as well as a number of other desirable properties for up to 11  voters, proving the optimality of the above bound.   we also obtain tight results for set - valued and probabilistic voting rules, which complement and significantly improve existing theorems.
we discuss the josephson current between two noncentrosymmetric superconductors.   the coexistence of superconducting order parameters between spin - singlet @xmath0 and helical @xmath1-wave spin - triplet @xmath2 enriches a variety of low - temperature behavior of josephson current depending on their relative amplitudes.   we will show that characteristic behaviors of the josephson current for @xmath3 are clearly different from those for @xmath4.   the topologically protected zero - energy surface bound states are responsible for the clear difference.   we conclude that the josephson current well reflects character of the topological surface states and the pairing symmetry of noncentrosymmetric superconductors.
we discuss the recent detection of a strong, organized magnetic field in the bright, broad - line b2v star, hr5907, using the espadons spectropolarimeter on the cfht as part of the magnetism in massive stars ( mimes ) survey.   we find a rotational period of 0.50833 days, making it the fastest - rotating, non - degenerate magnetic star ever detected. like the previous rapid - rotation record holder hr 7355 ( also discovered by mimes : oksala et al.   2010, rivinius et al.   2010 ), this star shows emission line variability that is diagnostic of a structured magnetosphere.
the  image of the merging, hot galaxy cluster e  reveals a bow shock propagating in front of a bullet - like gas cloud just exiting the disrupted cluster core.   this is the first clear example of a shock front in a cluster. from the jumps in the gas density and temperature at the shock,   the mach number of the bullet - like cloud is 23.   this corresponds to a velocity of 30004000  relative to the main cluster, which means that the cloud traversed the core just 0.10.2 gyr ago.   the 67 kev `` bullet '' appears to be a remnant of a dense cooling flow region once located at the center of a merging subcluster whose outer gas has been stripped by ram pressure.   the bullet s shape indicates that it is near the final stage of being destroyed by ram pressure and gas dynamic instabilities, as the subcluster galaxies move well ahead of the cool gas.   the unique simplicity of the shock front and bullet geometry in emay allow a number of interesting future measurements.   the cluster s average temperature is @xmath0 kev but shows large spatial variations.   the hottest gas ( @xmath1 kev ) lies in the region of the radio halo enhancement and extensive merging activity involving subclusters other than the bullet.
recently, holz & wald have presented a new method for determining gravitational lensing effects on, e.g., supernova luminosity versus redshift measurements in inhomogeneous universes. in this paper,   their method is generalized in several ways : first, the matter content is allowed to consist of several different types of fluids, possibly with non - vanishing pressure.   second, besides lensing by simple point masses and singular isothermal spheres, the more realistic halo dark matter distribution proposed by navarro, frenk & white ( nfw ), based on n - body simulation results, is treated.   we discuss various aspects of the accuracy of the method, such as luminosity corrections, and statistics, for multiple images.   we find in agreement with other recent work that a large sample of supernovae at large redshift could be used to extract gross features of the mass distribution of the lensing dark matter halos, such as the existence of a large number of point - like objects.   the results for the isothermal sphere and the nfw model are, however, very similar if normalized to the observed luminosity distribution of galaxies.   we give convenient analytical fitting formulas for our computed lensing probabilites as a function of magnification, for several redshifts.   + * key words : * cosmology : theory, gravitational lensing, dark matter  galaxies : halos
an s  matrix ansatz is used to determine the mass and width of the z boson, as well as the contributions of @xmath0/z interference and z boson exchange to fermion  pair production. for this purpose   we use hadron and lepton  pair production cross sections and lepton forward   backward asymmetries that have been measured with the l3 detector at centre  of  mass energies between 87  and 189 .
we consider the quasi - one dimensional system realized by an array of weakly coupled parallel one - dimensional `` tubes '' in a two - dimensional lattice which permits free motion of atoms in an axial direction in the presence of a zeeman field, rashba type spin orbit coupling ( soc ), and an @xmath0-wave attractive interaction, while the radial motion is tightly confined.   we solve the zero - temperature ( @xmath1 ) bogoliubov - de gennes ( bdg ) equations for the quasi-1d fermi gas with the dispersion modified by tunneling between the tubes, and show that the @xmath1 phase diagram hosts the fulde - ferrell - larkin - ovchinnikov ( fflo ) phase with non - zero center of mass momentum cooper pairs for small values of the soc while for larger values of the soc and high zeeman fields the uniform superfluid phase with zero center of mass momentum cooper pairs has an instability towards the topological uniform superfluid phase with majorana fermions at the tube ends.   also, we show that tuning the two - dimensional optical lattice strength in this model allows one to explore the crossover behaviors of the phases during the transition between the 3d and the 1d system and in general the fflo ( for small soc ) and the topological uniform superfluid phase ( for large soc ) are favored as the system becomes more one - dimensional.   we also find evidence of the existence of a zeeman tuned topological quantum phase transition ( tqpt ) within the fflo phase itself and for large values of the zeeman field and small soc the tqpt gives rise to a topologically distinct fflo phase.
this work provides a comprehensive scaling law based performance analysis for multi - cell multi - user massive multiple - input - multiple - output ( mimo ) downlink systems with maximal - ratio transmission ( mrt ).   imperfect channel state information ( csi ), pilot contamination, and channel spatial correlation are all considered.   first, a sum - rate lower bound is derived by exploiting the asymptotically deterministic property of the received signal power, while keeping the random nature of other components in the signal - to - interference - plus - noise - ratio ( sinr ) intact. via a general scaling model on important network parameters, including the number of users, the channel training energy and the data transmission power, with respect to the number of base station antennas, the asymptotic scaling law of the effective sinr is obtained, which reveals quantitatively the tradeoff of the network parameters.   more importantly, pilot contamination and pilot contamination elimination ( pce ) are considered in the analytical framework.   in addition, the applicability of the derived asymptotic scaling law in practical systems with large but finite antenna numbers are discussed.   finally, sufficient conditions on the parameter scalings for the sinr to be asymptotically deterministic in the sense of mean square convergence are provided, which covers existing results on such analysis as special cases and shows the effect of pce explicitly.   massive mimo, mutli - cell, csi error, pilot contamination, scaling law, mean square convergence.
we have studied the single - electron transport spectrum of a quantum dot in gaas / algaas resonant tunneling device.   the measured spectrum has irregularities indicating a broken circular symmetry.   we model the system with an external potential consisting of a parabolic confinement and a negatively charged coulombic impurity placed in the vicinity of the quantum dot.   the model leads to a good agreement between the calculated single - electron eigenenergies and the experimental spectrum.   furthermore, we use the spin - density - functional theory to study the energies and angular momenta when the system contains many interacting electrons. in the high magnetic field regime   the increasing electron number is shown to reduce the distortion induced by the impurity.
the bulk of the hydrogen in the universe transformed from neutral to ionized somewhere in the redshift interval @xmath0, most likely due to ionizing photons produced by an early generation of stars or mini  quasars.   the resulting free electrons, interacting with the cmb photons via thomson - scattering, are a mixed blessing, providing both a probe of the epoch of the first stars and a contaminant to the pristine primary anisotropy. here   we review our current knowledge of reionization with emphasis on inhomogeneities and describe the possible connections to cmb anisotropy.   epsf # 1= 0.8 # 1= 0.7 # 1#2#3#4#5#6#7    to#2   ''' ''    # 1    7.3 in = -0.4 in    # 1@xmath1#1 # 1@xmath2    2cm^-2 2cm^2 3cm^-3 3gcm^-3 # 1#1 # 1#23.6pt    # 1@xmath3 # 1#1 # 1#1 # 1#1 # 1#1 c 3mp@xmath4 m # 1#23.6pt    = cmmib10 u v
a four - dimensional static black hole solution of einstein equation conformally coupled to a massive and self interacting scalar field is obtained.   a nontrivial scalar solution proposes a weak scalar hair.   a dressed black hole shows a trace of scalar charge in the metric signalling the presence of scalar hair.   a number of metrics with regular horizons and temperatures are also proposed.
we consider a real scalar field and a majorana fermion field to construct a supersymmetric quantum theory of free fermion fields based on the deformed heisenberg algebra @xmath0=i\hbar\big(1-\beta p+2\beta^{2}p^{2}\big)$ ], where @xmath1 is a deformation parameter.   we present a deformed supersymmetric algebra in the presence of minimal length and maximal momentum. + * key words * : quantum gravity phenomenology, quantum field theory, supersymmetry
protein aggregation is of great importance in biology, e.g., in amyloid fibrillation.   the aggregation processes that occur at the cellular scale must be highly stochastic in nature because of the statistical number fluctuations that arise on account of the small system size at the cellular scale.   we study the nucleated reversible self - assembly of monomeric building blocks into polymer - like aggregates using the method of kinetic monte carlo.   kinetic monte carlo, being inherently stochastic, allows us to study the impact of fluctuations on the polymerisation reactions.   one of the most important characteristic features in this kind of problem is the existence of a lag phase before self - assembly takes off, which is what we focus attention on.   we study the associated lag time as a function of the system size and kinetic pathway.   we find that the leading order stochastic contribution to the lag time before polymerisation commences is inversely proportional to the system volume for large - enough system size for all nine reaction pathways tested.   finite - size corrections to this do depend on the kinetic pathway.
the effect of meson and isobar degrees of freedom in a(@xmath0 ) and a(@xmath1 ) is studied for four - momentum transfers @xmath2 in the range between 0.2 and 0.8  ( gev / c)@xmath3.   the calculations are performed in a non - relativistic framework with explicit @xmath4 degrees - of - freedom. for the whole range of momentum transfers under investigation the relative effect of the meson - exchange and isobar degrees of freedom   is significant. at low missing momenta and quasi - elastic conditions, a tendency to reduce the @xmath5 and @xmath6 differential cross sections is noticed.   the greatest sensitivity is found in the interference structure functions @xmath7 and @xmath8.   the recoil polarization observables, on the other hand, are moderately affected by the meson - exchange and @xmath9-isobar currents.
the logic of proofs, lp, and its successor, justification logic, is a refinement of the modal logic approach to epistemology in which proofs / justifications are taken into account. in 2000   kuznets showed that satisfiability for lp is in the second level of the polynomial hierarchy, a result which has been successfully repeated for all other one - agent justification logics whose complexity is known.   we introduce a family of multi - agent justification logics with interactions between the agents justifications, by extending and generalizing the two - agent versions of the logic of proofs introduced by yavorskaya in 2008.   known concepts and tools from the single - agent justification setting are adjusted for this multiple agent case.   we present tableau rules and some preliminary complexity results. in several cases   the satisfiability problem for these logics remains in the second level of the polynomial hierarchy, while for others it is or -hard.   furthermore, this problem becomes -hard even for certain two - agent logics, while there are @xmath0-hard logics of three agents.
the force laws governing the extension behavior of homopolypeptides are obtained from a phenomenological free energy capable of describing the helix - coil transition. just above the melting temperature of the free chains, @xmath0, the plot of force, @xmath1, _ vs. _   end - to - end distance, @xmath2, exhibits two plateaus associated with coexistence of helical and coil domains.   the lower plateau is due to tension induced onset of helix - coil transition.   the higher plateau corresponds to the melting of the helices by overextension. just below @xmath0 the @xmath3 plot exhibits only the upper plateau.   the @xmath3 plots, the helical fraction, the number of domains and their polydispersity are calculated for two models : in one the helical domains are viewed as rigid rods while in the second they are treated as worm like chains.    2
recently, hoava proposed a power counting renormalizable theory for ( 3 + 1)-dimensional quantum gravity, which reduces to einstein gravity with a non - vanishing cosmological constant in ir, but possesses improved uv behaviors. in this work  , we analyze the stability of the einstein static universe by considering linear homogeneous perturbations in the context of an ir modification of hoava gravity, which implies a ` soft'breaking of the ` detailed balance'condition.   the stability regions of the einstein static universe is parameterized by the linear equation of state parameter @xmath0 and the parameters appearing in the hoava theory, and it is shown that a large class of stable solutions exists in the respective parameter space.
we construct and discuss a toy model of the population of numerous non - identical extragalactic sources of ultra - high - energy cosmic rays. in the model, cosmic - ray particles   are accelerated in magnetospheres of supermassive black holes in galactic nuclei, the key parameter of acceleration being the black - hole mass.   we use astrophysical data on the redshift - dependent black - hole mass function to describe the population of these cosmic - ray accelerators, from weak to powerful, and confront the model with cosmic - ray data.
we present a statistical analysis of spectra of transfer matrices of classical lattice spin models ; this continues the work on the eight - vertex model of the preceding paper.   we show that the statistical properties of these spectra can serve as a criterion of integrability.   it provides also an operational numerical method to locate integrable varieties.   in particular, we distinguish the notions of integrability and criticality considering the two examples of the three - dimensional ising critical point and the two - dimensional three - state potts critical point. for complex spectra which appear frequently in the context of transfer matrices,   we show that the notion of independence of eigenvalues for integrable models still holds.
we study the one - shot zero - error classical capacity of a quantum channel assisted by quantum no - signalling correlations, and the reverse problem of exact simulation of a prescribed channel by a noiseless classical one.   quantum no - signalling correlations are viewed as two - input and two - output completely positive and trace preserving maps with linear constraints enforcing that the device can not signal. both problems lead to simple semidefinite programmes ( sdps ) that depend only on the kraus operator space of the channel. in particular  , we show that the zero - error classical simulation cost is precisely the conditional min - entropy of the choi - jamiokowski matrix of the given channel.   the zero - error classical capacity is given by a similar - looking but different sdp ; the asymptotic zero - error classical capacity is the regularization of this sdp, and in general we do not know of any simple form.   interestingly however, for the class of classical - quantum channels, we show that the asymptotic capacity is given by a much simpler sdp, which coincides with a semidefinite generalization of the fractional packing number suggested earlier by aram harrow.   this finally results in an operational interpretation of the celebrated lovsz @xmath0 function of a graph as the zero - error classical capacity of the graph assisted by quantum no - signalling correlations, the first information theoretic interpretation of the lovsz number.
we implement a decision procedure for answering questions about a class of infinite words that might be called ( for lack of a better name ) `` fibonacci - automatic ''.   this class includes, for example, the famous fibonacci word @xmath0, the fixed point of the morphism @xmath1 and @xmath2.   we then recover many results about the fibonacci word from the literature ( and improve some of them ), such as assertions about the occurrences in @xmath3 of squares, cubes, palindromes, and so forth. as an application of our method we prove a new result   : there exists an aperiodic infinite binary word avoiding the pattern @xmath4.   this is the first avoidability result concerning a nonuniform morphism proven purely mechanically.   corollary (almost ) theorem lemma proposition    definition example conjecture open problem procedure    remark
a key problem in quantum computing is finding a viable technological path toward the creation of a scalable quantum computer.   one possible approach toward solving part of this problem is distributed computing, which provides an effective way of utilizing a network of limited capacity quantum computers.    in this paper, we present two primitive operations, cat - entangler and cat - disentangler, which in turn can be used to implement non - local operations, e.g. non - local cnot and quantum teleportation. we also show how to establish an entangled pair, and use entangled pairs to efficiently create a generalized ghz state.   furthermore, we present procedures which allow us to reuse channel qubits in a sequence of non - local operations.   these non - local operations work on the principle that a cat - like state, created by cat - entangler, can be used to distribute a control qubit among multiple computers. using this principle  , we show how to efficiently implement non - local control operations in many situation, including a parallel implementation of a certain kind of unitary transformation.   finally, as an example, we present a distributed version of the quantum fourier transform.
we present two new measurements constraining lorentz and cpt violation using the @xmath0xe/@xmath1he zeeman maser and atomic hydrogen masers.   experimental investigations of lorentz and cpt symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity.   the two - species @xmath0xe/@xmath1he zeeman maser bounds violations of cpt and lorentz symmetry of the neutron at the @xmath2 gev level. measurements with atomic hydrogen masers provide a clean limit of cpt and lorentz symmetry violation of the proton at the @xmath3 gev level.   oddhead__arabic@page evenheadarabic@page    in the proc.   3rd int.   symp.  on sym.  in subatomic phys
interaction of domain walls ( dws ) in ferromagnetic stripes is studied with relevance to the formation of stable complexes of many domains.   two dw system is described with the landau - lifshitz - gilbert equation including regimes of narrow and wide stripes which correspond the presence of transverse and vortex dws.   the dws of both kinds are characterized with their chiralities ( the direction of the magnetization rotation in the stripe plane ) and polarities ( the magnetization orientation in the center of a vortex and/or halfvortices ), hence, their interactions are analyzed with dependence on these properties.   in particular, pairs of the dws of opposite or like chiralities and polarities are investigated as well as pairs of opposite ( like ) chiralities and of like ( opposite ) polarities.   conditions of the creation of stationary magnetic bubbles built of two interacting dws are formulated with relevance to the situations of presence and absence of the external magnetic field.
in this paper, we present surface brightness profiles for 79 globular clusters in m31, using images observed with _ hubble space telescope _, some of which are from new observations.   the structural and dynamical parameters are derived from fitting the profiles to several different models for the first time.   the results show that in the majority of cases, king models fit the m31 clusters as well as wilson models, and better than srsic models. however, there are 11 clusters best fitted by srsic models with the srsic index @xmath0, meaning that they have cuspy central density profiles  . these clusters may be the well - known core - collapsed candidates.   there is a bimodality in the size distribution of m31 clusters at large radii, which is different from their galactic counterparts. in general, the properties of clusters in m31 and the milky way fall in the same regions of parameter spaces.   the tight correlations of cluster properties indicate a `` fundamental plane '' for clusters, which reflects some universal physical conditions and processes operating at the epoch of cluster formation.
prior - weighted logistic regression has become a standard tool for calibration in speaker recognition.   logistic regression is the optimization of the expected value of the logarithmic scoring rule.   we generalize this via a parametric family of proper scoring rules.   our theoretical analysis shows how different members of this family induce different relative weightings over a spectrum of applications of which the decision thresholds range from low to high.   special attention is given to the interaction between prior weighting and proper scoring rule parameters.   experiments on nist sre12 suggest that for applications with low false - alarm rate requirements, scoring rules tailored to emphasize higher score thresholds may give better accuracy than logistic regression.    * index terms * : speaker recognition, calibration, proper scoring rule
while the connection between long gamma - ray bursts ( grbs ) and type ib / c supernovae ( sne   ib / c ) from stripped stars has been well - established, one key outstanding question is what conditions and factors lead to each kind of explosion in massive stripped stars.   one promising line of attack is to investigate what sets apart sne ib / c * with * grbs from those * without * grbs.   here, i briefly present two observational studies that probe the sn properties and the environmental metallicities of sne ib / c ( specifically broad - lined sne ic ) with and without grbs.   i present an analysis of expansion velocities based on published spectra and on the homogeneous spectroscopic cfa data set of over 70 sne of types iib, ib, ic and ic - bl, which triples the world supply of well - observed stripped sne.   moreover, i demonstrate that a meta - analysis of the three published sn ib / c metallicity data sets, when including only values at the sn positions to probe natal oxygen abundances, indicates at very high significance that indeed sne ic erupt from more metal - rich environments than sne ib, while sne ic - bl with grbs still prefer, on average, more metal - poor sites than those without grbs.
we compare the time evolution of entanglement measures after local operator excitation in the critical ising model with predictions from conformal field theory. for the spin operator and its descendants   we find that rnyi entropies of a block of spins increase by a constant that matches the logarithm of the quantum dimension of the conformal family.   however, for the energy operator we find a small constant contribution that differs from the conformal field theory answer equal to zero.   we argue that the mismatch is caused by the subtleties in the identification between the local operators in conformal field theory and their lattice counterpart.   our results indicate that evolution of entanglement measures in locally excited states not only constraints this identification, but also can be used to extract non - trivial data about the conformal field theory that governs the critical point.   we generalize our analysis to the ising model away from the critical point, states with multiple local excitations, as well as the evolution of the relative entropy after local operator excitation and discuss universal features that emerge from numerics.   nordita-2016 - 56
this paper presents color transformations for hst nicmos camera 2 observations to the ground - based cit / ctio photometric system, using observations of nineteen moderately bright, red stars in baade s window in the color range @xmath0.   we estimate an extension of the transformation to @xmath1 with five standards observed by stsci.   convolving near - ir spectra taken above the atmosphere with different filter transmission profiles, we simulate both nicmos and ground - based photometry, obtaining results which are consistent with our transformation and its extension.
there are only a few tracers available to probe the kinematics of individual early - type galaxies beyond one effective radius. here   we directly compare a sample of planetary nebulae ( pne ), globular clusters ( gcs ) and galaxy starlight velocities out to @xmath04 effective radii, in the s0 galaxy ngc 2768.   using a bulge - to - disk decomposition of a k - band image we assign pne and starlight to either the disk or the bulge.   we show that the bulge pne and bulge starlight follow the same radial density distribution as the red subpopulation of gcs, whereas the disk pne and disk starlight are distinct components.   we find good kinematic agreement between the three tracers to several effective radii ( and with stellar data in the inner regions ).   further support for the distinct nature of the two galaxy components come from our kinematic analysis.   after separating the tracers into bulge and disk components we find the bulge to be a slowly rotating pressure - supported system, whereas the disk reveals a rapidly rising rotation curve with a declining velocity dispersion profile.   the resulting v@xmath1/@xmath2 ratio for the disk resembles that of a spiral galaxy and hints at an origin for ngc 2768 as a transformed late - type galaxy. a two - component kinematic analysis for   a sample of s0s will help to elucidate the nature of this class of galaxy.       globular clusters  planetary nebulae  galaxies : individual ( ngc 2768 )
we study a model for the observed phenomenon of electron spin resonance ( esr ) at the zeeman frequency as seen by a scanning tunneling microscope ( stm ) via its current noise.   the model for this esr - stm phenomenon allows the stm current to flow in two arms of a nanoscopic interferometer, one arm has direct tunneling from the tip to the substrate while the second arm has tunneling through two spin states.   we evaluate analytically the noise spectrum for non - polarized leads, as relevant to the experimental setup.   we show that spin - orbit interactions allow for an interference of two tunneling paths resulting in a resonance effect.
* we provide evidence that indicate the star cluster pfleiderer2, which is projected in a rich field, as a newly identified galactic globular cluster. *   since it is located in a crowded field, core extraction and decontamination tools were applied to reveal the cluster sequences in b, v and i color - magnitude diagrams ( cmds ).   the main cmd features of pfleiderer2 are a tilted red giant branch, and a red horizontal branch, indicating a high metallicity around solar.   the reddening is e(b - v)=1.01.   the globular cluster is located at a distance from the sun d@xmath0 = 16@xmath12 kpc.   the cluster is located at 2.7 kpc above the galactic plane and at a distance from the galactic center of r@xmath2=9.7kpc, which is unusual for a metal - rich globular cluster.
we study here the curious particle dynamics resulting from electro - osmotic flow around a microchannel junction corner whose dielectric walls are weakly polarizable.   the hydrodynamic velocity field is obtained via superposition of a linear irrotational term associated with the equilibrium zeta potentials of both the microchannel and particle surfaces and the non - linear induced - charge electro - osmotic flow which originates from the interaction of the externally applied electric field on the charge cloud it induces at the solid - liquid interface.   the particle dynamics are analyzed by considering dielectrophoretic forces via the addition of a mobility term to the flow field in the limit of stokes drag law.   the former, non - divergence free term is responsible for migration of particles towards the sharp microchannel junction corner, where they can potentially accumulate.   experimental observations of particle trapping for various applied electric fields and microparticle size are rationalized in terms of the growing relative importance of the dielectrophoretic force and induced - charge contributions to the global velocity field with increasing intensity of the externally applied electric field.
an interesting feature of the giant planets of our solar system is the existence of regions around these objects where no irregular satellites are observed.   surveys have shown that, around jupiter, such a region extends from the outermost regular satellite callisto, to the vicinity of themisto, the innermost irregular satellite. to understand the reason for the existence of such a _ satellite - void _ region, we have studied the dynamical evolution of jovian irregulars by numerically integrating the orbits of several hundred test particles, distributed in a region between 30 and 80 jupiter - radii, for different values of their semimajor axes, orbital eccentricities, and inclinations. as expected, our simulations indicate that objects in or close to the influence zones of the galilean satellites become unstable because of interactions with ganymede and callisto.   however, these perturbations can not account for the lack of irregular satellites in the entire region between callisto and themisto.   it is suggested that at distances between 60 and 80 jupiter - radii, ganymede and callisto may have long - term perturbative effects, which may require the integrations to be extended to times much longer than 10 myr.   the interactions of irregular satellites with protosatellites of jupiter at the time of the formation of jovian regulars may also be a destabilizing mechanism in this region.   we present the results of our numerical simulations and discuss their applicability to similar satellite void - regions around other giant planets.
we study the joint spectral properties of photon pairs generated by spontaneous parametric down - conversion in a one - dimensional nonlinear photonic crystal in a collinear, degenerate, type - ii geometry.   we show that the photonic crystal properties may be exploited to compensate for material dispersion and obtain photon pairs that are nearly factorable, in principle, for arbitrary materials and spectral regions, limited by the ability to fabricate the nonlinear crystal with the required periodic variation in the refractive indices for the ordinary and extraordinary waves.
concepts from ergodic theory are used to describe the existence of special non - transitive maps in attractors of phase synchronous chaotic oscillators. in particular  , it is shown that for a class of phase - coherent oscillators, these special maps imply phase synchronization.   we illustrate these ideas in the sinusoidally forced chua s circuit and two coupled rssler oscillators.   furthermore, these results are extended to other coupled chaotic systems.   in addition, a phase for a chaotic attractor is defined from the tangent vector of the flow.   finally, it is discussed how these maps can be used to a real - time detection of phase synchronization in experimental systems.   +   , chaotic phase synchronization, ergodic theory, temporal mappings    05.45.-a, 0.5.45.xt, 05.45.-r, 02.45.ac +
the exotic neutrinoless @xmath0 nuclear conversion is studied within the conventional extensions of the standard model as well as in the minimal supersymmetric ( susy ) models with and without r - parity conservation.   the dependence of the @xmath1 conversion rates on the nucleon and nuclear structure is consistently taken into account. using our calculated transition matrix elements and the available experimental data on the branching ratio @xmath2 for @xmath3ti and @xmath4pb as well as the expected experimental sensitivity for @xmath5al employed as a target in   the planned at brookhaven @xmath6 conversion ( meco ) experiment, we extract very severe constraints for the flavor violation parameters.   we especially emphasize on the constraints resulting for susy r - parity violating parameters.    6.5 in    # 1    # 10= -.015em0 - 0.03em0 - 0 -.015em.0233em0    * lepton flavor violation : constraints from exotic muon to electron conversion * +    t.s.   kosmas @xmath7 and sergey kovalenko @xmath8 + @xmath7__division of theoretical physics, university of ioannina gr-45110 ioannina, greece _ _   + @xmath9__departamento de fsica, universidad tcnica federico santa mara, casilla 110-v, valparaso, chile _ _
* abstract *    an analysis of some modified gravity models, based on the study of pure schwarzschild and of schwarzschild - de sitter black holes, and involving the use of the noether charge method, is carried out.   corrections to the classical einsteinian black hole entropy appear.   it is shown explicitly how the condition of positive entropy can be used in order to constrain the viability of modified gravity theories.
the possibility of physics in multiple time dimensions is investigated.   drawing on recent work by walter craig and myself @xcite, i show that, contrary to conventional wisdom, there is a well - posed initial value problem  deterministic, stable evolution  for theories in multiple time dimensions.   though similar in many ways to ordinary, single - time theories, multi - time theories have some rather intriguing properties which suggest new directions for the understanding of fundamental physics.
we discuss the non - anticommutative ( @xmath0 ) supersymmetric wess - zumino model in four dimensions.   firstly we introduce differential operators which implement the non - anticommutative supersymmetry algebra acting on the component fields and action.   then we perform the renormalisation of the model up to two - loop order, including the complete set of terms necessary for renormalisability.   we show that ( at least up to this order ) the results obtained when we eliminate the auxiliary field after renormalisation are equivalent to those obtained when we eliminate the auxiliary fields before quantisation.   lth799 +    the non - anticommutative supersymmetric wess - zumino model + * i.  jack, d.r.t.   jones and r. purdy * + dept. of mathematical sciences, university of liverpool, liverpool l69 3bx, uk +
selected recent qcd and top - quark results from the tevatron are reviewed, aiming to illustrate progression from basic studies of qcd processes to verification of perturbative calculations and monte carlo simulation tools, and to their applications in more novel and complex cases, like top - quark studies and searches for new physics.
magnetic monopole ; sheaf cohomology ; + topological quantisation ; spin structure ; dirac operator using a sheaf - theoretic extension of conventional principal bundle theory, the dirac monopole is formulated as a spherically symmetric model free of singularities outside the origin such that the charge may assume arbitrary real values. for integral charges,   the construction effectively coincides with the usual model.   spin structures and dirac operators are also generalised by the same technique.
in this paper, we apply a method identified by puerari & dottori to find the corotation radii ( cr ) in spiral galaxies. we apply our method to 57 galaxies,   17 of which have already have their cr locations determined using other methods.   the method we adopted entails taking fourier transforms along radial cuts in the @xmath0, @xmath1, @xmath2, @xmath3, and @xmath4 wavebands and comparing the phase angles as a function of radius between them.   the radius at which the phase angles cross indicates the location of the corotation radius.   we then calculated the relative bar pattern speed, @xmath5, and classified the bar as `` fast '', where @xmath6, slow, where @xmath7, or intermediate, where the errors on @xmath5 are consistent with the bar being `` slow '' or `` fast ''.   for the 17 galaxies that had their cr locations previously measured, we found that our results were consistent with the values of @xmath5 obtained by the computer simulations of rautiainen, salo & laurikainen.   for the larger sample, our results indicate that 34 out of 57 galaxies ( @xmath860% ) have fast bars.   we discuss these results in the context of its implications for dark matter concentrations in disk galaxies.   we also discuss these results in the context of different models for spiral structure in disk galaxies.       galaxies : spiral  galaxies : structure
a systematic study of 160 heavy and super - heavy nuclei is performed in the hartree - fock - bogoliubov approach with the finite range and density dependent gogny force with the d1s parameter set.   we show calculations in several approximations : with axially symmetric and reflexion symmetric wave functions, with axially symmetric and non - reflexion symmetric wave functions and finally some representative examples with triaxial wave functions are also discussed.   relevant properties of the ground state and along the fission path are thoroughly analyzed.   fission barriers, q@xmath0-factors and lifetimes with respect to fission and @xmath1-decay as well as other observables are discussed.   larger configuration spaces and more general hfb wave functions as compared to previous studies provide a very good agreement with the experimental data.   +   +
we suppose that the doping of the 2d hard - core boson system away from half - filling may result in the formation of multi - center topological inhomogeneity ( defect ) such as charge order ( co ) bubble domain(s ) with bose superfluid ( bs ) and extra bosons both localized in domain wall(s ), or a _ topological _ co+bs _ phase separation _, rather than an uniform mixed co+bs supersolid phase.   starting from the classical model we predict the properties of the respective quantum system.   the long - wavelength behavior of the system is believed to remind that of granular superconductors, cdw materials, wigner crystals, and multi - skyrmion system akin in a quantum hall ferromagnetic state of a 2d electron gas.    to elucidate the role played by quantum effects and that of the lattice discreteness we have addressed the simplest nanoscopic counterpart of the bubble domain in a checkerboard co phase of 2d hc - bh square lattice.   it is shown that the relative magnitude and symmetry of multi - component order parameter are mainly determined by the sign of the @xmath0 and @xmath1 transfer integrals. in general  , the topologically inhomogeneous phase of the hc - bh system away from the half - filling can exhibit the signatures both of @xmath2, and @xmath3 symmetry of the off - diagonal order.
the paper deals with the ground and the first excited state of the polaron in the one dimensional holstein  model. various variational methods are used to investigate both the weak coupling and strong coupling case, as well as the crossover regime between them.   two of the methods, which are presented here for the first time, introduce interesting elements to the understanding of the nature of the polaron.   reliable numerical evidence is found that, in the strong coupling regime, the ground and the first excited state of the self - trapped polaron are well described within the adiabatic limit.   the lattice vibration modes associated with the self - trapped polarons are analyzed in detail, and the frequency softening of the vibration mode at the central site of the small polaron is estimated.   it is shown that the first excited state of the system in the strong coupling regime corresponds to the excitation of the soft phonon mode within the polaron. in the crossover regime, the ground and the first excited state of the system can be approximated by the anticrossing of the self - trapped and the delocalized polaron state. in this way, the connection between the behavior of the ground and the first excited state is qualitatively explained.
in this paper, we propose a quantum field theoretical renormalization group approach to the vortex dynamics of magnetically coupled layered superconductors, to supplement our earlier investigations on the josephson - coupled case.   we construct a two - dimensional multi - layer sine - gordon type model which we map onto a gas of topological excitations. with a special choice of the mass matrix for our field theoretical model,   vortex dominated properties of magnetically coupled layered superconductors can be described.   the well known interaction potentials of fractional flux vortices are consistently obtained from our field - theoretical analysis, and the physical parameters ( vortex fugacity and temperature parameter ) are also identified.   we analyse the phase structure of the multi - layer sine  gordon model by a differential renormalization group method for the magnetically coupled case from first principles.   the dependence of the transition temperature on the number of layers is found to be in agreement with known results based on other methods.
we consider the diffusion of markers in a layered medium, with the lateral diffusion coefficient being the function of hight.   we show that the probability density of the lateral displacements follows one - dimensional batchelor s equation with time - dependent diffusion coefficient governed by the particles redistribution in height. for the film of a finite thickness   the resulting mean squared displacement exhibits superdiffusion at short times and crosses over to normal diffusion at long times.   the approach is used for description of experimental results on inhomogeneous molecular diffusion in thin liquid films deposited on solid surfaces.    _   * highlights : * _    * we show that vertical layering of liquid leads to superdiffusion behavior of walking markers * finite film thickness cause the asymptotical transition from superdiffusion to normal diffusion * conditional independence of orthogonal walks for 2d fokker - plank equation gives 1d batchelor s    anomalous diffusion, thin films, layered medium
we have analyzed the shot noise of electron emission under strong applied electric fields within the landauer - bttiker scheme.   in contrast to the previous studies of vacuum - tube emitters, we show that in new generation electron emitters, scaled down to the nanometer dimensions, shot noise much smaller than the schottky noise is observable.   carbon nanotube field emitters are among possible candidates to observe the effect of shot - noise suppression caused by quantum partitioning.
the subject of this work is the patrolling of an environment with the aid of a team of autonomous agents.   we consider both the design of open - loop trajectories with optimal properties, and of distributed control laws converging to optimal trajectories. as performance criteria,   the _ refresh time _ and the _ latency _ are considered, i.e., respectively, time gap between any two visits of the same region, and the time necessary to inform every agent about an event occurred in the environment.   we associate a graph with the environment, and we study separately the case of a chain, tree, and cyclic graph. for the case of chain graph, we first describe a minimum refresh time and latency team trajectory, and we propose a polynomial time algorithm for its computation.   then, we describe a distributed procedure that steers the robots toward an optimal trajectory. for the case of tree graph,   a polynomial time algorithm is developed for the minimum refresh time problem, under the technical assumption of a constant number of robots involved in the patrolling task.   finally, we show that the design of a minimum refresh time trajectory for a cyclic graph is _ np - hard _, and we develop a constant factor approximation algorithm.
it is shown that all the @xmath0 dyon bound states exist and are unique in @xmath1 and @xmath2 with four massless flavours supersymmetric su(2 ) yang - mills theories, where @xmath3 and @xmath4 are any relatively prime integers.   the proof can be understood in the context of field theory alone, and does _ not _ rely on any duality assumption.   we also give a general physical argument showing that these theories should have at least an exact @xmath5 duality symmetry, and then deduce in particular the existence of the @xmath6 vector multiplets in the @xmath7 theory.   the corresponding massive theories are studied in parallel, and it is shown that though in these cases the spectrum is no longer self - dual at a given point on the moduli space, it is still in perfect agreement with an exact s duality.   we also discuss the interplay between our results and both the semiclassical quantization and the heterotic - type ii string - string duality conjecture.   epsf = bbm12 = bbm9 = bbm7 = = =    1= 2= 3= specialpagefalse oddhead-1.2cm3 evenheadoddhead
in this paper, we study the evolution of the vortex filament equation ( vfe ), @xmath0    with @xmath1 being a regular planar polygon. using algebraic techniques, supported by full numerical simulations,   we give strong evidence that @xmath2 is also a polygon at any rational time ; moreover, it can be fully characterized, up to a rigid movement, by a generalized quadratic gau sum.   we also study the fractal behavior of @xmath3, relating it with the so - called riemann s non - differentiable function, that was proved by jaffard to be a multifractal.
we analyze the class of single qubit channels with the environment modeled by a one - qubit mixed state.   the set of affine transformations for this class of channels is computed analytically, employing the canonical form for the two - qubit unitary operator.   we demonstrate that, @xmath0 of the generalized depolarizing channels can be simulated by the one - qubit mixed state environment by explicitly obtaining the shape of the volume occupied by this class of channels within the tetrahedron representing the generalized depolarizing channels.   further, as a special case, we show that the two - pauli channel can not be simulated by a one - qubit mixed state environment.
we present newly calculated low - temperature opacities for gas with a primordial chemical composition.   in contrast to earlier calculations which took a pure metal - free hydrogen / helium mixture, we take into account the small fractions of deuterium and lithium as resulting from standard big bang nucleosynthesis.   our opacity tables cover the density range @xmath0 < -2 $ ] and temperature range of @xmath1 < 4.6 $ ], while previous tables were usually restricted to @xmath2. we find that, while the presence of deuterium does not significantly alter the opacity values, the presence of lithium gives rise to major modifications of the opacities, at some points increasing it by approximately 2 orders of magnitude relative to pure hydrogen / helium opacities.        nuclear reactions, nucleosynthesis, abundances  cosmology : early universe  atomic data  molecular data
we report on long - term x - ray timing of two anomalous x - ray pulsars, 1rxs  j170849.0@xmath0400910  and 1e  2259 + 586, using the _ rossi x - ray timing explorer. _ in monthly observations made over 1.4  yr and 2.6  yr for the two pulsars, respectively, we have obtained phase - coherent timing solutions which imply that these objects have been rotating with great stability throughout the course of our observations. for 1rxs  j170849.0@xmath0400910  , we find a rotation frequency of 0.0909169331(5 ) hz and frequency derivative @xmath1  hz  s@xmath2, for epoch mjd 51215.931. for 1e  2259 + 586  , we find a rotation frequency of 0.1432880613(2 )  hz, and frequency derivative @xmath3  hz  s@xmath2, for epoch mjd 51195.583.   rms phase residuals from these simple models are only @xmath40.01 cycles for both sources.   we show that the frequency derivative for 1e  2259 + 586  is inconsistent with that inferred from incoherent frequency observations made over the last 20  yr. our observations are consistent with the magnetar hypothesis and make binary accretion scenarios appear unlikely.    to appear in the astrophysical journal letters
compared to the the classical first - order grnwald - letnikov formula at time @xmath0, we firstly propose a second - order numerical approximate scheme for discretizing the riemann - liouvile derivative at time @xmath1, which is very suitable for constructing the crank - niclson technique applied to the time - fractional differential equations.   the established formula has the following form @xmath2 where the coefficients @xmath3 @xmath4 can be determined via the following generating function @xmath5 applying this formula to the time fractional cable equations with riemann - liouville derivative in one or two space dimensions. then the high - order   compact finite difference schemes are obtained.   the solvability, stability and convergence with orders @xmath6 and @xmath7 are shown, where @xmath8 is the temporal stepsize and @xmath9, @xmath10, @xmath11 are the spatial stepsizes, respectively. finally, numerical experiments are provided to support the theoretical analysis. +   + * key words * : riemann - liouville derivative ; generating function ; the energy method. +
this paper introduces a new optimal control model to describe and control the dynamics of infectious diseases. in the present model,   the average time of isolation ( i.e. hospitalization ) of infectious population is the main time - dependent parameter that defines the spread of infection.   all the preventive measures aim to decrease the average time of isolation under given constraints.
we study the low - bias stabilization of active magnetic bearings ( ambs ) subject to voltage saturation based on a recently proposed model for the amb switching mode of operation. using a forwarding - like approach, we construct a stabilizing controller of arbitrarily small amplitude and a control - lyapunov function for the amb  dynamics.   we illustrate our construction using a numerical example.
the stochastic dynamics of micron and nanoscale cantilevers immersed in a viscous fluid are quantified.   analytical results are presented for long slender cantilevers driven by brownian noise.   the spectral density of the noise force is not assumed to be white and the frequency dependence is determined from the fluctuation - dissipation theorem.   the analytical results are shown to be useful for the micron scale cantilevers that are commonly used in atomic force microscopy.   a general thermodynamic approach is developed that is valid for cantilevers of arbitrary geometry as well as for arrays of multiple cantilevers whose stochastic motion is coupled through the fluid. it is shown that the fluctuation - dissipation theorem permits the calculation of stochastic quantities via straightforward deterministic methods. the thermodynamic approach is used with deterministic finite element numerical simulations to quantify the autocorrelation and noise spectrum of cantilever fluctuations for a single micron scale cantilever and the cross - correlations and noise spectra of fluctuations for an array of two experimentally motivated nanoscale cantilevers as a function of cantilever separation.   the results are used to quantify the noise reduction possible using correlated measurements with two closely spaced nanoscale cantilevers.
we compare and contrast the entangling properties of a three - well bose - hubbard model and an optical beamsplitter.   the coupling between the different modes is linear in both cases, and we may identify two output modes.   obvious differences are that our bose - hubbard model, with only the middle well initially occupied, does not have a vacuum input port, there is no equivalent of a collisional, @xmath0 nonlinearity with the beamsplitter, and the results of the bose - hubbard model show a time - dependence. in the non - interacting case,   we obtain analytic solutions and show that, like a beamsplitter, the bose - hubbard system will not produce entanglement for classical initial states.   we also show that whether inseparability or entanglement are detected depends sensitively on the criteria measured, with different criteria giving contradictory predictions.
chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. such polarization, significantly enhanced above thermal equilibrium,   is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long - lived charge - separated states in photosynthetic reaction centers.   we will here show that the recently understood fundamental quantum dynamics of radical - ion - pair reactions open up a new and completely unexpected venue towards obtaining cidnp signals.   the fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations on the order of @xmath0 times or more higher than the thermal equilibrium value at earth s magnetic field relevant to natural photosynthesis.   this opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis.
we have obtained optical spectra of seven stars in the old galactic cluster that are unusual sources of x - rays, and investigate whether the x - ray emission is due to magnetic activity or to mass transfer.   the two binaries below the giant branch s1063 and   s1113, the giant with the white dwarf companion s1040 and the eccentric binary on the subgiant branch s1242 show magnetic activity in the form of h&k emission and h@xmath0 emission, suggesting that their x - rays are coronal.   the reason for the enhanced activity level in s1040 is not clear.   the two wide, eccentric binaries s1072 and s1237 and the blue straggler s1082 do not show evidence for h&k emission.   a second spectral component is found in the spectrum of s1082, most clearly in the variable h@xmath0 absorption profile.   we interpret this as a signature of the proposed hot subluminous companion.
we investigate the possibility that the broken spatial inversion symmetry by a trap potential induces a spin - triplet cooper - pair amplitude in an @xmath0-wave superfluid fermi gas.   being based on symmetry considerations, we clarify that this phenomenon may occur, when a spin rotation symmetry of the system is also broken.   we also numerically confirm that a triplet pair amplitude is really induced under this condition, using a simple model.   our results imply that this phenomenon is already present in a trapped @xmath0-wave superfluid fermi gas with spin imbalance. as an interesting application of this phenomenon, we point out that one may produce a @xmath1-wave superfluid fermi gas, by suddenly changing the @xmath0-wave pairing interaction to a @xmath1-wave one by using the feshbach resonance technique.   since a cooper pair is usually classified into the spin - singlet ( and even - parity ) state and the spin - triplet ( and odd - parity ) state, our results would be useful in considering how to mix them with each other in a superfluid fermi gas.   such admixture has recently attracted much attention in the field of non - centrosymmetric superconductivity, so that our results would also contribute to the further development of this research field, on the viewpoint of cold fermi gas physics.
the structural profiles and electronic properties of pentacene ( c@xmath0h@xmath1 ) multilayers on ag(111 ) surface has been studied within the density functional theory ( dft ) framework.   we have performed first - principle total energy calculations based on the projector augmented wave ( paw ) method to investigate the initial growth patterns of pentacene ( pn ) on ag(111 ) surface. in its bulk phase, pentacene crystallizes with a triclinic symmetry while a thin film phase having an orthorhombic unit cell is energetically less favorable by 0.12 ev / cell.   pentacene prefers to stay planar on ag(111 ) surface and aligns perfectly along silver rows without any molecular deformation at a height of 3.9 . at one monolayer ( ml )   coverage the separation between the molecular layer and the surface plane extends to 4.1  due to intermolecular interactions weakening surface   pentacene attraction.   while the first ml remains flat, the molecules on a second full pentacene layer deposited on the surface rearrange so that they become skewed with respect to each other.   this adsorption mode is energetically more preferable than the one for which the molecules form a flat pentacene layer by an energy difference similar to that obtained for bulk and thin film phases.   moreover, as new layers added, pentacenes assemble to maintain this tilting for 3 and 4 ml similar to its bulk phase while the contact layer always remains planar.   therefore, our calculations indicate bulk - like initial stages for the growth pattern.
a simple numerical model is used to simulate the effect of vertical taps on a packing of monodisperse hard spheres.   our results are in good agreement with an experimental work done in chicago and with other previous models, especially concerning the dynamics of the compaction, the influence of the excitation strength on the compaction efficiency, and some ageing effects.   the principal asset of the model is that it allows a local analysis of the packings.   vertical and transverse density profiles are used as well as size and volume distributions of the pores.   an interesting result concerns the appearance of a vertical gradient in the density profiles during compaction.   furthermore, the volume distribution of the pores suggests that the smallest pores, ranging in size between a tetrahedral and an octahedral site, are not strongly affected by the tapping process, in contrast to the largest pores which are more sensitive to the compaction of the packing.    2
we observed b1600 + 434  and b1608 + 656  with cxo / acis, detecting both quasar images in b1600 + 434  and three of four images in b1608 + 656.   we did not detect significant x - ray emission from nearby galaxy groups or clusters associated with each lens galaxy.   the upper limits on the x - ray luminosity of any cluster within 4  of each lens and at each lens redshift are of @xmath0 and @xmath1  for b1600 + 434  and b1608 + 656, respectively.   the radio - loud source quasars have power - law photon indices of @xmath2 and @xmath3 and x - ray luminosities of @xmath410@xmath5 and @xmath6  for b1600 + 434  and b1608 + 656, respectively before correcting for the magnification.   we detected a differential absorption column density of @xmath7 between the two images of b1600 + 434, roughly consistent with expectations from differential extinction estimates of @xmath8  mag and a standard dust - to - gas ratio.   the differential absorption observed in gravitational lenses may serve as an important probe to study the gas content in high redshift galaxies since it can separate the absorbing column originating from the lens galaxy and those intrinsic to quasars.   we also detected 157 serendipitous x - ray sources in the two _ chandra _  fields and identified the brighter optical counterparts using the sdss and dposs surveys.
the main aim of this paper is to establish the connection between well - known criteria for the pseudocontinuability of a non - inner schur function @xmath0 in the unit disk ( see theorems   and  ). in a canonical way we associate a probability measure @xmath1 on the unit circle with @xmath0.   one of the two criteria will be reformulated in the face of @xmath1, whereas the other one is drafted in view of a completely non  unitary contraction @xmath2 having @xmath0 as its corresponding characteristic function.   our main result clarifies an immediate connection between the above - mentioned two criteria. for this reason  , we construct a special orthogonal basis in the space @xmath3 and rewrite these criteria in terms of this orthogonal basis.   ( see theorem   ).
we have recently shown that there is a limit to quantum coherence in many - particle spin qubits due to spontaneous symmetry breaking.   these results were derived for the lieb - mattis spin model. here   we will show that the underlying mechanism of decoherence in systems with spontaneous symmetry breaking is in fact more general.   we present here a generic route to finding the decoherence time associated with spontaneous symmetry breaking in many particle qubits, and subsequently we apply this approach to two model systems, indicating how the continuous symmetries in these models are spontaneously broken and discussing the relation of this symmetry breaking to the thin spectrum.   we then present in detail the calculations that lead to the limit to quantum coherence, which is due to energy shifts in the thin spectrum.
a grid - based real - space implementation of the projector augmented wave ( paw ) method of p. e. blchl [ phys. rev.   b * 50 *, 17953 ( 1994 ) ] for density functional theory ( dft ) calculations is presented.   the use of uniform 3d real - space grids for representing wave functions, densities and potentials allows for flexible boundary conditions, efficient multigrid algorithms for solving poisson and kohn - sham equations, and efficient parallelization using simple real - space domain - decomposition.   we use the paw method to perform all - electron calculations in the frozen core approximation, with smooth valence wave functions that can be represented on relatively coarse grids.   we demonstrate the accuracy of the method by calculating the atomization energies of twenty small molecules, and the bulk modulus and lattice constants of bulk aluminum.   we show that the approach in terms of computational efficiency is comparable to standard plane - wave methods, but the memory requirements are higher.
shallow cores in bright, massive galaxies are commonly thought to be the result of scouring of stars by mergers of binary supermassive black holes.   past investigations have suggested correlations between the central black hole mass and the stellar light or mass deficit in the core, using proxy measurements of @xmath0  or stellar mass - to - light ratios ( @xmath1 ).   drawing on a wealth of dynamical models which provide both @xmath0  and @xmath1, we identify cores in 23 galaxies, of which 20 have direct, reliable measurements of @xmath0  and dynamical stellar mass - to - light ratios ( @xmath2 ).   these cores are identified and measured using core - srsic model fits to surface brightness profiles which extend out to large radii ( typically more than the effective radius of the galaxy ) ; for approximately one fourth of the galaxies, the best fit includes an outer ( srsic ) envelope component.   we find that the core radius is most strongly correlated with the black hole mass and that it correlates better with total galaxy luminosity than it does with velocity dispersion.   the strong core - size@xmath0  correlation enables estimation of black hole masses ( in core galaxies ) with an accuracy comparable to the @xmath0@xmath3 relation ( rms scatter of 0.30 dex in @xmath4 ), without the need for spectroscopy.   the light and mass deficits correlate more strongly with galaxy velocity dispersion than they do with black hole mass.   stellar mass deficits span a range of 0.239 @xmath0, with almost all ( 87% ) being @xmath5 ; the median value is 2.2 @xmath0.
we perform kinetic monte carlo simulations of flow - induced nucleation in polymer melts with an algorithm that is tractable even at low undercooling.   the configuration of the non - crystallized chains under flow is computed with a recent non - linear tube model.   our simulations predict both enhanced nucleation and the growth of shish - like elongated nuclei for sufficiently fast flows.   the simulations predict several experimental phenomena and theoretically justify a previously empirical result for the flow - enhanced nucleation rate.   the simulations are highly pertinent to both the fundamental understanding and process modeling of flow - induced crystallization in polymer melts.
a @xmath0-submodular function is a generalization of submodular and bisubmodular functions.   this paper establishes a compact representation for minimizers of a @xmath0-submodular function by a poset with inconsistent pairs ( pip ).   this is a generalization of ando   fujishige s signed - poset representation for minimizers of a bisubmodular function.   we completely characterize the class of pips ( elementary pips ) arising from @xmath0-submodular functions.   we give algorithms to construct the elementary pip of minimizers of a @xmath0-submodular function @xmath1 for three cases : ( i ) a minimizing oracle of @xmath1 is available, ( ii ) @xmath1 is network - representable, and ( iii ) @xmath1 arises from a potts energy function.   furthermore, we provide an efficient enumeration algorithm for all maximal minimizers of a potts @xmath0-submodular function. our results are applicable to obtain all maximal persistent labelings in actual computer vision problems.   we present experimental results for real vision instances.   + * keywords : * @xmath0-submodular function, birkhoff representation theorem, poset with inconsistent pairs ( pip ), potts energy function
the detection of an afterglow, following a @xmath0-ray burst ( grb ), can be described reasonably well by synchrotron emission from a relativistic spherical expanding blast wave, driven by an expanding fireball.   we perform detailed calculations considering the emission from the whole region behind the shock front.   we use the blandford mckee self similar adiabatic solution to describe the fluid behind the shock. using this detailed model,   we derive expressions for the peak flux, and the peak frequency at a given observed time.   these expressions provide important numerical corrections to previous, more simplified models.   we calculate the observed light curve and spectra for several magnetic field models.   we show that both the light curve and the spectra are flat near the peak.   this rules out the interpretation of the optical peak of grb970508 as the peak of the light curve, predicted by the existing fireball models.   we calculate the observed image of a grb afterglow.   the observed image is bright near the edge and dimmer at the center, thus creating a ring.   the contrast between the edge and the center is larger at high frequencies and the width of the ring is smaller.
we calculate the neutrino mean free path in color superconducting quark matter, and employ it to study the cooling of matter via neutrino diffusion in the superconducting phase as compared to a free quark phase.   the cooling process slows when quark matter undergoes a second order phase transition to a superconducting phase at the critical temperature @xmath0.   cooling subsequently accelerates as the temperature decreases below @xmath0.   this will directly impact the early evolution of a newly born neutron star, should its core contain quark matter.   consequently, there may be observable changes in the early neutrino emission which would provide evidence for superconductivity in hot and dense matter.
we present a kinetic theory for the evolution of the phase - space distribution of dark matter particles in galaxy halos in the presence of a cosmological spectrum of fluctuations.   this theory introduces a new way to model the formation and evolution of halos, which traditionally have been investigated by analytic gravitational infall models or numerical n - body methods. unlike the collisionless boltzmann equation,   our kinetic equation contains nonzero terms on the right - hand side arising from stochastic fluctuations in the gravitational potential due to substructures in the dark matter mass distribution. using statistics for constrained gaussian random fields in standard cosmological models,   we show that our kinetic equation to second - order in perturbation theory is of the fokker - planck form, with one scattering term representing drift and the other representing diffusion in velocity - space.   the drift is radial, and the drift and diffusion coefficients depend only on positions and not velocities ; our relaxation process in the quasilinear regime is therefore different from the standard two - body relaxation.   we provide explicit expressions relating these coefficients to the linear power spectrum of mass fluctuations and present results for the currently favored cold dark matter model with a nonzero cosmological constant.   solutions to this kinetic equation will provide a complete description of the cold dark matter spatial and velocity distributions for the average halo during the early phases of galaxy halo formation.
moderately luminous starbursts in the nearby universe often occur in disk galaxies that are at most subject to mild external perturbations.   an investigation of this type of galaxy leads to a better understanding of starburst triggering mechanisms and the resulting star formation processes, and provides useful comparisons to more extreme starbursts seen at high redshifts.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
the structure of the concentration field of a decaying substance produced by chemical sources and advected by a smooth incompressible two - dimensional flow is investigated.   we focus our attention on the non - uniformities of the hlder exponent of the resulting filamental chemical field.   they appear most evidently in the case of open flows where irregularities of the field exhibit strong spatial intermittency as they are restricted to a fractal manifold.   non - uniformities of the hlder exponent of the chemical field in closed flows appears as a consequence of the non - uniform stretching of the fluid elements.   we study how this affects the scaling exponents of the structure functions, displaying anomalous scaling, and relate the scaling exponents to the distribution of finite - time lyapunov exponents of the advection dynamics.   theoretical predictions are compared with numerical experiments.
a cascade model has been developed to study pion induced multichannel reactions ( quasielastic, scx, dcx, absorption and @xmath0-production ) at pion energies above @xmath1 gev.   the inclusive pion double - charge - exchange ( dcx ) reaction on @xmath2 and @xmath3 nuclei in the energy range from @xmath4 to @xmath5 gev is analyzed.   pion energy spectra and double differential cross section are calculated.   the pion production is a determinant feature in the high energy pion nucleus reactions, and non pion production, dcx signal is sizeable only at forward angles and for high energy outgoing pions.   it is shown that the contribution to inclusive dcx processes of the conventional mechanism, with two ( or more ) quasielastic scx steps decreases very fast as a function of the energy and reaches very low values at energies above @xmath6.   this opens the opportunity of having sizeable contributions of exotic mechanisms that are negligible at the @xmath7-resonance energies.
in stochastic optimization, the population risk is generally approximated by the empirical risk. however, in the large - scale setting, minimization of the empirical risk may be computationally restrictive. in this paper, we design an efficient algorithm to approximate the population risk minimizer in generalized linear problems such as binary classification with surrogate losses and generalized linear regression models.   we focus on large - scale problems, where the iterative minimization of the empirical risk is computationally intractable, i.e., the number of observations @xmath0 is much larger than the dimension of the parameter @xmath1, i.e. @xmath2. we show that under random sub - gaussian design, the true minimizer of the population risk is approximately proportional to the corresponding ordinary least squares ( ols ) estimator. using this relation  , we design an algorithm that achieves the same accuracy as the empirical risk minimizer through iterations that attain up to a cubic convergence rate, and that are cheaper than any batch optimization algorithm by at least a factor of @xmath3.   we provide theoretical guarantees for our algorithm, and analyze the convergence behavior in terms of data dimensions.   finally, we demonstrate the performance of our algorithm on well - known classification and regression problems, through extensive numerical studies on large - scale datasets, and show that it achieves the highest performance compared to several other widely used and specialized optimization algorithms.
we study the competence between chiral symmetry restoration and two flavor color superconductivity ( 2sc ) using a relativistic quark model with covariant nonlocal interactions.   we consider two different nonlocal regulators : a gaussian regulator and a lorentzian regulator.   we find that although the phase diagrams are qualitative similar to those obtained using models with local interactions, in our case the superconducting gaps at medium values of the chemical potential are larger.   consequently, we obtain that in that region the critical temperatures for the disappearance of the 2sc phase might be of the order of 100 - 120 mev.   we also find that for ratios of the quark - quark and quark - antiquark couplings somewhat above the standard value 3/4, the end point and triple point in the @xmath0 phase diagram meet and a phase where both the chiral and diquark condensates are non - negligible appears.    * two flavor color superconductivity in nonlocal chiral quark models * +   r. s. duhau@xmath1, a. g. grunfeld@xmath1 and n.n.   scoccola@xmath2 + @xmath1 _ physics department, comisin nacional de energa atmica, + av.libertador 8250, ( 1429 ) buenos aires, argentina.   _ + @xmath3 _ conicet, rivadavia 1917, ( 1033 ), argentina.   _ + @xmath4 _ universidad favaloro, sols 453, ( 1078 ) buenos aires, argentina _   pacs numbers : 12,39.ki.12.38.mh.
we study the statics and dynamics of a stable, mobile, three - dimensional matter - wave spherical quantum ball created in the presence of an attractive two - body and a _ very small _ repulsive three - body interaction.   the quantum ball can propagate with a constant velocity in any direction in free space and its stability under a small perturbation is established numerically and variationally. in frontal head - on and angular collisions at large velocities two quantum balls behave like quantum solitons.   such collision is found to be quasi elastic and the quantum balls emerge after collision without any change of direction of motion and velocity and with practically no deformation in shape. when reflected by a hard impenetrable plane, the quantum ball bounces off like a wave obeying the law of reflection without any change of shape or speed.   however, in a collision at small velocities two quantum balls coalesce to form a larger ball which we call a quantum - ball breather.   we point out the similarity and difference between the collision of two quantum and classical balls.   the present study is based on an analytic variational approximation and a full numerical solution of the mean - field gross - pitaevskii equation using the parameters of @xmath0li atoms.
we study bond - order parameters for generalized @xmath0-@xmath1 models on a square lattice. using the plane - wave limit the considered order parameters form basis functions for irreducible representations of the symmetry transformations of the point group and of time reversal.   we show that for instability wave vectors along the diagonals all possible basis functions are either fine - tuned ( i.e., obey restrictions beyond the requirements of symmetry ) or break time reversal symmetry and thus describe flux states.   for instability wave vectors along the crystalline axes, corresponding to the observed case in underdoped cuprates, there are only three representations with @xmath2, @xmath3, and @xmath4 symmetry which do not break time reversal symmetry in the general case.   we suggest that one of them has recently been observed in resonant elastic x - ray scattering.
in recent years the scintillation mechanism of inorganic crystals has been extensively investigated in different studies @xcite.   the main issues are the _ non - proportionality _ mechanism of the light response versus energy and its connection with the shaping time used for the scintillation signals. in this   study the compton coincidence technique has been used to measure the relative _ non - proportionality _ of three crystals : cdwo@xmath0, bgo, and nai(tl ). to test the _ non - proportionality _ dependence on shaping time, the preamplified scintillator pulses have been digitized and shaped with a digital trapezoidal filter. since   no analogic shaping occurs the majority of the scintillation components are digitized, thus avoiding major information losses.   the obtained results suggest the existence of a correlation between the time constant of the scintillation emission and light yield.
we study the structure and stability of discrete breathers ( both pinned and mobile ) in two - dimensional nonlinear anisotropic schrdinger lattices. starting from a set of identical one - dimensional systems we develop the continuation of the localized pulses from the weakly coupled regime ( strongly anisotropic ) to the homogeneous one ( isotropic ).   mobile discrete breathers are seen to be a superposition of a localized mobile core and an extended background of two - dimensional nonlinear plane waves.   this structure is in agreement with previous results on one - dimensional breather mobility.   the study of the stability of both pinned and mobile solutions is performed using standard floquet analysis.   regimes of quasi - collapse are found for both types of solutions, while another kind of instability ( responsible for the discrete breather fission ) is found for mobile solutions.   the development of such instabilities is studied examining typical trajectories on the unstable nonlinear manifold.      ,    and    05.45.@xmath0a, 63.20.pw
structural and physical properties determined by measurements on large single crystals of the anisotropic ferromagnet mnbi are reported.   the findings support the importance of magneto - elastic effects in this material.   x - ray diffraction reveals a structural phase transition at the spin reorientation temperature @xmath0 = 90 k. the distortion is driven by magneto - elastic coupling, and upon cooling transforms the structure from hexagonal to orthorhombic.   heat capacity measurements show a thermal anomaly at the crystallographic transition, which is suppressed rapidly by applied magnetic fields.   effects on the transport and anisotropic magnetic properties of the single crystals are also presented.   increasing anisotropy of the atomic displacement parameters for bi with increasing temperature above @xmath0 is revealed by neutron diffraction measurements.   it is likely that this is directly related to the anisotropic thermal expansion in mnbi, which plays a key role in the spin reorientation and magnetocrystalline anisotropy.   the identification of the true ground state crystal structure reported here may be important for future experimental and theoretical studies of this permanent magnet material, which have to date been performed and interpreted using only the high temperature structure.
we evaluate the next - to - leading order correction to the nambu - jona - lasinio model starting from quantum chromodynamics.   we show that a systematic expansion exists, starting from a given set of exact classical solutions, so that higher order corrections could in principle be computed at any order. in this way  , we are able to fix the constants of the nambu - jona - lasinio model from quantum chromodynamics and analyze the behavior of strong interactions at low energies.   the technique is to expand in powers of currents of the generating functional.   we apply it to a simple yukawa model with self - interaction showing how this has a nambu - jona - lasinio model and its higher order corrections as a low - energy limit. the same is shown to happen for quantum chromodynamics in the chiral limit with two quarks.   we prove stability of the njl model so obtained.   then, we prove that the correction term we obtained does not change the critical temperature of the chiral transition of the nambu - jona - lasinio model at zero chemical potential.
we propose a new method of measuring the third and fourth moments of return distribution based on quadratic variation method when the return process is assumed to have zero drift.   the realized third and fourth moments variations computed from high frequency return series are good approximations to corresponding actual moments of the return distribution.   an investor holding an asset with skewed or fat - tailed distribution is able to hedge the tail risk by contracting the third or fourth moment swap under which the float leg of realized variation and the predetermined fixed leg are exchanged.   thus constructed portfolio follows more gaussian - like distribution and hence the investor effectively hedge the tail risk.
establishing bounds on the accuracy achievable by localization techniques represents a fundamental technical issue.   bounds on localization accuracy have been derived for cases in which the position of an agent is estimated on the basis of a set of observations and, possibly, of some a priori information related to them ( e.g., information about anchor positions and properties of the communication channel ). in this manuscript   new bounds are derived under the assumption that the localization system is _ map - aware _, i.e., it can benefit not only from the availability of observations, but also from the a priori knowledge provided by the _ map _ of the environment where it operates.   our results show that : a ) map - aware estimation accuracy can be related to some features of the map ( e.g., its shape and area ) even though, in general, the relation is complicated ; b ) maps are really useful in the presence of some combination of low signal - to - noise ratios and specific geometrical features of the map ( e.g., the size of obstructions ) ; c ) in most cases, there is no need of refined maps since additional details do not improve estimation accuracy.   localization, cramer - rao bound, ziv - zikai bound, weiss - weinstein bound, a priori information, map.
this review summarizes recent attempts to reconstruct the expansion history of the universe and to probe the nature of dark energy.   reconstruction methods can be broadly classified into parametric and non - parametric approaches.   it is encouraging that, even with the limited observational data currently available, different approaches give consistent results for the reconstruction of the hubble parameter @xmath0 and the effective equation of state @xmath1 of dark energy.   model independent reconstruction using current data allows for modest evolution of dark energy density with redshift.   however, a cosmological constant (= dark energy with a constant energy density ) remains an excellent fit to the data.   some pitfalls to be guarded against during cosmological reconstruction are summarized and future directions for the model independent reconstruction of dark energy are explored.
in this study we investigated indirect manifestations of color octet electron at the next generation linear colliders : international linear collider ( ilc ) and compact linear collider ( clic ).   namely, production of two gluons via color octet electron exchange is considered.   signal and background analysis have been performed taking into account initial state radiation and beamstrahlung.   we show that color octet electron ( @xmath0 ) manifestation will be seen upto @xmath1 tev and @xmath2 tev at ilc and clic with @xmath3 tev, respectively.   clic with @xmath4 tev will be sensitive upto @xmath5 tev.
we propose a dynamical generalized polynomial chaos ( dgpc ) method to solve time - dependent stochastic partial differential equations ( spdes ) with white noise forcing.   the long - time simulation of spde solutions by polynomial chaos ( pc ) methods is notoriously difficult as the dimension of the stochastic variables increases linearly with time. exploiting the markovian property of white noise,   dgpc @xcite implements a restart procedure that allows us to expand solutions at future times in terms of orthogonal polynomials of the measure describing the solution at a given time and the future white noise.   the dimension of the representation is kept minimal by application of a karhunen  loeve ( kl ) expansion. using frequent restarts and low degree polynomials on sparse multi - index sets,   the method allows us to perform long time simulations, including the calculation of invariant measures for systems which possess one.   we apply the method to the numerical simulation of stochastic burgers and navier stokes equations with white noise forcing.   our method also allows us to incorporate time - independent random coefficients such as a random viscosity.   we propose several numerical simulations and show that the algorithm compares favorably with standard monte carlo methods.   keywords : stochastic partial differential equations, uncertainty quantification, polynomial chaos, karhunen - loeve expansion
we study the properties of strange quark matter in equilibrium with normal nuclear matter. instead of using the conventional bag model in quark sector, we achieve the confinement by a density - dependent quark mass derived from in - medium chiral condensates. in nuclear matter  , we adopt the equation of state from the brueckner - bethe - goldstone approach with three - body forces.   it is found that the mixed phase can occur, for a reasonable confinement parameter, near the normal nuclear saturation density, and goes over into pure quark matter at about 5 times the saturation.   the onset of mixed and quark phases is compatible with the observed class of low - mass neutron stars, but it hinders the occurrence of kaon condensation.
the essential quantum many - body physics of an ultracold quantum gas relies on the single - particle green s functions.   we demonstrate that it can be extracted by the spectrum of electromagnetically induced transparency ( eit ).   the single - particle green s function can be reconstructed by the measurements of frequency moments in eit spectroscopy.   this optical measurement provides an efficient and nondestructive method to reveal the many - body properties, and we propose an experimental setup to realize it.  finite temperature and finite size effects are discussed, and we demonstrate the reconstruction steps of green s function for the examples of three - dimensional mott - insulator phase and one - dimensional luttinger liquid.
a multivariate analysis of gamma - ray burst ( grb ) bulk properties is presented to discriminate between distinct classes of grbs.   several variables representing burst duration, fluence and spectral hardness are considered.   two multivariate clustering procedures are used on a sample of 797 bursts from the third batse catalog : a nonparametric average linkage hierarchical agglomerative clustering procedure validated with wilks @xmath0 and other manova tests ; and a parametric maximum likelihood model - based clustering procedure assuming multinormal populations calculated with the em algorithm and validated with the bayesian information criterion.   the two methods yield very similar results.   the batse grb population consists of three classes with the following duration / fluence / spectrum bulk properties : class i with long / bright / intermediate bursts, class ii with short / hard / faint bursts, and class iii with intermediate / intermediate / soft bursts.   one outlier with poor data is also present.   classes i and ii correspond to those reported by kouveliotou et al.   ( 1993 ), but class iii is clearly defined here for the first time.
we study the thermoelectrical transports for an interacting dot attached to two graphene electrodes.   graphene band structure shows a pseudogap density of states that affects strongly the transport properties. in this work,   we focus on the coulomb blockade regime and derive the expression for onsager matrix @xmath0 that relates the electrical and heat currents with electrical and thermal biases in the linear response regime.   our findings show double peak structures for the electrical and thermal conductances versus the dot level in accordance with the coulom blockade phenomenon.   remarkably, however, the thermal conductance is much smaller than the electrical conductance, resulting in high figure of merit value for some gate voltage.   finally, we report a large departure from the wiedemann - franz law caused mainly by the pseudogap density of states in the contacts and weakly affected by interactions.
we investigate spin - charge mixing effect on resonant tunneling in spin - polarized tomonaga - luttinger liquid with double impurities.   the mixing arises from fermi velocity difference between two spin species due to zeeman effect.   zero bias conductance is calculated as a function of gate voltage @xmath0, gate magnetic field @xmath1, temperature and magnetic field applied to the system.   mixing effect is shown to cause rotation of the lattice pattern of the conductance peaks in @xmath2 plane, which can be observed in experiments. at low temperatures,   the contour shapes are classified into three types, reflecting the fact that effective barrier potential is renormalized towards `` perfect reflection '', `` perfect transmission '' and magnetic field induced `` spin - filtering '', respectively.
we consider a scattering of two identical blocks of mass @xmath0 in one dimension by exchanging momenta through elastic collisions with a ball with mass @xmath1.   initially, a ball and a block are at rest with the distance of @xmath2 and the other block is incident on the ball. for @xmath3,   the three objects make multiple collisions.   the analytic expressions for the final velocities of the three - body problem are derived by making use of the conservation of energy and momentum.   the rates for energy and momentum transfer are computed as functions of @xmath4.   we find all possible values for @xmath4 at which the initial energy and momentum of the incident block are completely transferred to the scattered block.
we present predictions for two statistical measures of the hydrogen reionization process at high redshift.   the first statistic is the number of neutral segments identified in spectra of high redshift qsos as a function of their length.   the second is the cross - correlation of neutral regions with possible sources of ionizing radiation.   these independent probes are sensitive to the topology of the ionized regions.   if reionization proceeded from high to low density regions then the cross - correlation will be negative, while if voids were ionized first then we expect a positive correlation and a relatively small number of long neutral segments.   we test the sensitivity of these statistics for reionization by stars in high redshift galaxies.   the flux of ionizing radiation emitted from stars is estimated by identifying galaxies in an n - body simulation using a semi - analytic galaxy formation model.   the spatial distribution of ionized gas is traced in various models for the propagation of the ionization fronts.   a model with ionization proceeding from high to low density regions is consistent with the observations of becker et al.   ( 2001 ), while models in which ionization begins in the lowest density regions appear to be inconsistent with the present data.
we present results from an archival study of 70 medium - redshift qsos observed with the wide field planetary camera 2 on board the _ hubble space telescope_. the qsos have magnitudes @xmath0 ( total nuclear plus host light ) and redshifts @xmath1.   a close relationship between qso host and nucleus is found by examining multiple parameters at once.   a principal components analysis shows that 3 nuclear and host properties are related in a kind of fundamental plane : nuclear luminosity and the size and effective surface magnitude of the bulge.   using optical nuclear luminosity, this relationship explains 95.9% of the variance in the overall sample, while 94.9% of the variance is accounted for if we use x - ray nuclear luminosity.   the form of this qso fundamental plane shows similarities to the well - studied fundamental plane of elliptical galaxies, and we examine the possible relationship between them as well as the difficulties involved in establishing this connection.   the key to the relationship might lie in the fueling mechanism of the central black hole.   quasars, galaxies : active    98.54.-h
we investigate two coupled nonlinear cavities that are coherently driven in a dissipative environment.   we perform semiclassical, numerical and analytical quantum studies of this dimer model when both cavities are symmetrically driven. in the semiclassical analysis, we find steady - state solutions with different photon occupations in two cavities.   such states can be considered analogs of the closed system double well symmetry breaking states.   we analyze the occurrence and properties of these localized states in the system parameter space and examine how the symmetry breaking states, in form of a bistable pair, are associated to the single cavity bistable behavior. in a full quantum calculation of the master equation dynamics that includes quantum fluctuations, the symmetry breaking states and bistability disappear due to the quantum fluctuations. in quantum trajectory picture  , we observe enhanced quantum jumps and switching which indicate the presence of the underlying semiclassical symmetry breaking states.   finally, we present a set of analytical solutions for the steady state correlation functions using the complex p - representation and discuss its regime of validity.
we study the transverse momentum dependence of the landau - pomeranchuk - migdal effect in qed, starting from the high energy expansion of the solution of the dirac equation in the presence of an external field.   the angular integrated energy loss formula differs from an earlier expression of zakharov by taking finite kinematical boundaries into account. in an expansion in powers of the opacity of the medium  , we derive explicit expressions for the radiation cross section associated with @xmath0, @xmath1 and @xmath2 scatterings.   we verify the bethe - heitler and the factorization limit, and we calculate corrections to the factorization limit proportional to the square of the target size.   a closed form expression valid to arbitrary orders in the opacity is derived in the dipole approximation.   the resulting radiation spectrum is non - analytic in the coupling constant which is traced back to the transverse momentum broadening of a hard parton undergoing multiple small angle molire scattering. in extending the results to qcd, we test a previously used dipole prescription by comparing to direct pqcd results for @xmath0 and @xmath1. for @xmath0,   the qcd dipole prescription reproduces exactly the bertsch - gunion radiation spectrum. for @xmath3  , we find a sizeable correction which reduces to a multiplicative factor 17/8 at large separation.
the permeability of two - dimensional fractures with self - affine fractal roughness is studied via analytic arguments and numerical simulations.   the limit where the roughness amplitude is small compared with average fracture aperture is analyzed by a perturbation method, while in the opposite case of narrow aperture, we use heuristic arguments based on lubrication theory.   numerical simulations, using the lattice boltzmann method, are used to examine the complete range of aperture sizes, and confirm the analytic arguments.
observations of the cosmic microwave background have revealed a component of 1060  ghz emission from the galaxy which correlates with 100140@xmath0 m emission from interstellar dust but has an intensity much greater than expected for the low - frequency tail of the `` electric dipole vibrational '' emission peaking at @xmath1130@xmath0 m.   this `` anomalous emission '' is more than can be accounted for by dust - correlated free - free emission.   the anomalous emission could be due in part to magnetic dipole emission from thermal fluctuations of the magnetization within interstellar dust grains, but only if a substantial fraction of the fe in interstellar dust resides in magnetic materials such as metallic iron or magnetite.   the observed anomalous emission is probably due primarily to electric dipole radiation from spinning ultrasmall interstellar dust grains.   this rotational emission is expected to be partially polarized.
the quarkonium hadroproduction in association with a photon at high energies provides a probe of the dynamics of the strong interactions as it is dependent on the nuclear gluon distribution.   therefore, it could be used to constrain the behavior of the nuclear gluon distribution in proton - nucleus and nucleus - nucleus collisions.   such processes are useful to single out the magnitude of the shadowing / antishadowing effects in the nuclear parton densities. in this work   we investigate the influence of nuclear effects in the production of @xmath0 and @xmath1 and estimate the transverse momentum dependence of the nuclear modification factors. the theoretical framework considered in the @xmath2 ( @xmath3 )   production associated with a direct photon at the hadron collider is the non - relativistic qcd ( nrqcd ) factorization formalism.
the charge transported when a quantum pump is adiabatically driven by time - dependent external forces in presence of dissipation is given by the line integral of a pumping field @xmath0.   we give a general expression of @xmath0 in terms of quantum correlation functions evaluated at fixed external forces.   hence, an advantage of our method is that it transforms the original time - dependent problem into an autonomous one.   yet another advantage is that the curl of @xmath0 gives immediate visual information about the geometric structures governing dissipative quantum pumping.   this can be used in a wide range of experimental cases, including electron pumps based on quantum dots and cooper - pair pumps based on superconducting devices.   applied to a cooper - pair sluice, we find an intriguing dissipation - induced enhancement of charge pumping, reversals of current, and emergence of asymmetries.   this geometric method thus enables one to unveil a plethora of beneficial, dissipation - assisted operation protocols.
the dissociation spectrum of the hydrogen molecular ion by short intense pulses of infrared light is calculated.   the time - dependent schrdinger equation is discretized and integrated in position and momentum space. for few - cycle pulses one can resolve vibrational structure that commonly arises in the experimental preparation of the molecular ion from the neutral molecule.   we calculate the corresponding energy spectrum and analyze the dependence on the pulse time - delay, pulse length, and intensity of the laser for @xmath0 nm. we conclude that the proton spectrum is a both a sensitive probe of the vibrational dynamics and the laser pulse. finally we compare our results with recent measurements of the proton spectrum for 55 fs pulses using a ti : sapphire laser ( @xmath1 nm ). integrating over the laser focal volume, for the intensity @xmath2w @xmath3, we find our results are in excellent agreement with these experiments.    _ to be submitted to j. phys.   b _
the effects of differences between the local and global values of the hubble parameter on the cosmologies consistent with studies of high - redshift type ia supernov  are discussed.   it is found that with a local hubble parameter around 10 per cent higher than the global value then open cosmological models ( such as @xmath0 ) are prefered and if the local value is around 20 per cent higher then standard cosmological models ( @xmath1 ) can be recovered. even in the case where the hubble parameter ratio is 1  , low @xmath2 open cosmologies with @xmath3 are not rejected at the 95 per cent confidence level.
i review the main steps made so far towards a detailed ( semi ) analytical model for the hierarchical clustering of bound virialized objects ( i.e., haloes ) in the gravitational instability scenario.   i focus on those models relying on the spherical collapse approximation which have led to the most complete description.   the work is divided in two parts : a first one dealing with the mass function of objects and a second one dealing with the growth times and rates.
we investigate the dynamics of two interacting electrons in coupled quantum dots driven by an ac field.   we find that the two electrons can be trapped in one of the dots by the ac field, in spite of the strong coulomb repulsion.   in particular, we find that the interaction may enhance the localization effect.   we also demonstrate the field excitation procedure to generate the maximally entangled bell states.   the generation time is determined by both analytic and numerical solutions of the time dependent schrdinger equation.pacs numbers : 03.65.ud, 78.67.hc, 73.23.-bkeywords : coupled quantum dots, dynamical localization, entanglement    acknowledgement algorithm axiom claim conclusion condition conjecture corollary criterion definition example exercise lemma notation problem proposition remark solution summary
point defects such as interstitials, vacancies, and impurities in otherwise perfect crystals induce complex displacement fields that are of long - range nature. in the present paper   we study numerically the response of a two - dimensional colloidal crystal on a triangular lattice to the introduction of an interstitial particle.   while far from the defect position the resulting displacement field is accurately described by linear elasticity theory, lattice effects dominate in the vicinity of the defect. in comparing the results of particle based simulations with continuum theory,   it is crucial to employ corresponding boundary conditions in both cases. for the periodic boundary condition used here  , the equations of elasticity theory can be solved in a consistent way with the technique of ewald summation familiar from the electrostatics of periodically replicated systems of charges and dipoles.   very good agreement of the displacement fields calculated in this way with those determined in particle simulations is observed for distances of more than about 10 lattice constants.   closer to the interstitial, strongly anisotropic displacement fields with exponential behavior can occur for certain defect configurations. here   we rationalize this behavior with a simple bead - spring that relates the exponential decay constant to the elastic constants of the crystal.
a problem of finding stationary states of open quantum systems is addressed.   we focus our attention on a generic type of open system : a qubit coupled to its environment.   we apply the theory of block operator matrices and find stationary states of two  level open quantum systems under certain conditions applied both on the qubit and the surrounding.
we theoretically investigate the supercurrent - induced magnetization dynamics of a two - dimensional lattice of ferromagnetically ordered spins placed on a conventional superconductor with broken spatial inversion symmetry and strong spin - orbit coupling.   we develop a phenomenological description of the coupled dynamics of the superconducting condensate and the spin system, and demonstrate that supercurrents produce a reactive spin - orbit torque on the magnetization. by performing a microscopic self - consistent calculation, we show that the spin - orbit torque originates from a spin - polarization of the cooper pairs due to current - induced spin - triplet correlations.   interestingly, we find that there exists an intrinsic limitation for the maximum achievable spin - orbit torque, which is determined by the coupling strength between the condensate and the spin system. in proximitized hole - doped semiconductors,   the maximum achievable spin - orbit torque field is estimated to be on the order of @xmath0 mt, which is comparable to the critical field for current - induced magnetization switching in ferromagnetic semiconductors.
in the synchrotron radiation model, the polarization property depends on both the configuration of the magnetic field and the geometry of the visible emitting region. some peculiar behaviors in the x - ray afterglows of _ swift _ gamma - ray bursts ( grbs ), such as energetic flares and the plateau followed by a sharp drop, might by highly linearly - polarized because the outflows powering these behaviors may be poynting - flux dominated. furthermore, the broken - down of the symmetry of the visible emitting region may be hiding in current x - ray data and will give rise to interesting polarization signatures. in this work   we focus on the polarization accompanying the very early sharp decline of grb x - ray afterglows.   we show that strong polarization evolution is possible in both the high latitude emission model and the dying central engine model which are used to interpret this sharp x - ray decline.   it is thus not easy to efficiently probe the physical origin of the very early x - ray sharp decline with future polarimetry.   strong polarization evolution is also possible in the decline phase of x - ray flares and in the shallow decline phase of x - ray light curves characterized by chromatic x - ray vs. optical breaks.   an _ xrt_-like detector but with polarization capability on board a _ swift_-like satellite would be suitable to test our predictions.    gamma rays : bursts @xmath0 polarization @xmath0 grbs : jets and outflows @xmath0 radiation mechanisms : nonthermal
we examine the early angular momentum history of stars in young clusters via 197 photometric periods in the orion flanking fields, 83 photometric periods in ngc 2264, and 256 measurements of @xmath0 in the onc.   we show that pms stars, even those without observable disks, apparently do not conserve stellar angular momentum as they evolve down their convective tracks, but instead evolve at nearly constant angular velocity.   this result is inconsistent with expectations that convective stars lacking disks should spin up as they contract, but paradoxically consistent with disk - locking models.   we briefly explore possible resolutions, including disk locking, birthline effects, stellar winds, and planetary companions.   we have found no plausible explanations for this paradox.
critical software systems face stringent requirements in safety, security, and reliability due to the circumstances surrounding their operation.   safety and security have progressively gained importance over the years due to the integration of hardware with software - intensive deployments that introduce additional sources of errors.   it is, then, necessary to follow high - quality exhaustive software development processes that besides the needed development activities to increase safety and security also integrate techniques to increase the reliability of the software development process itself. in practice,   the use of automated techniques for the _ verification of the verification process _ is, however, not sufficiently wide spread.   this is mainly due to the high cost of the required techniques and to their degree of complexity when adjusting to the different norms and regulations.   this work presents an approach for comprehensive management of the verification processes ; the approach allows engineers to monitor and control the project status regarding the applicable standards.   this approach has been validated through its implementation in a tool and its application to real projects.
the d / h ratio of water in protostellar systems is a result of both inheritance from the parent molecular cloud and isotopic exchange in the disc.   a possibly widespread feature of disc evolution, ignored in previous studies, is accretion bursts ( or fu orionis outbursts ), which may thermally process a large fraction of the water.   one proposed underlying mechanism for fu orionis outbursts relies on the presence of a magnetically dead zone. here   we examine the evolution of ( d / h)@xmath0 in 1d simulations of a disc s evolution that include dead zones and infall from an envelope with given d / h ratio in the infalling water ( @xmath1 ), and compare the results with similar calculations without dead zones.   we find that the accretion bursts result in a significantly lower ( d / h)@xmath0 ratio and a more extended region ( radius up to @xmath2 au ) where water is equilibrated with hydrogen gas ( d / h=@xmath3 ), when compared to burst - free models.   solar system constraints suggest that our solar nebula either experienced no accretion bursts and had a schmidt number @xmath4 or had a schmidt number closer to `` nominal '' values ( @xmath5 ) and experienced several accretion bursts.   finally, future observations of ( d / h)@xmath0 in protoplanetary discs will allow inferences about angular momentum properties of the disc during disc building and the role of accretion bursts.       accretion, accretion discs - magnetohydrodynamics ( mhd ) - stars : pre - main sequence - planetary systems : protoplanetary discs - astrochemistry - comets : general
the experimental observation of quantum phenomena in strongly correlated many particle systems is difficult because of the short length- and timescales involved.   obtaining at the same time detailed control of individual constituents appears even more challenging and thus to date inhibits employing such systems as quantum computing devices.   substantial progress to overcome these problems has been achieved with cold atoms in optical lattices, where a detailed control of collective properties is feasible but it is very difficult to address and hence control or measure individual sites. here we show, that polaritons, combined atom and photon excitations, in an array of cavities such as a photonic crystal or coupled toroidal micro - cavities, can form a strongly interacting many body system, where individual particles can be controlled and measured.   all individual building blocks of the proposed setting have already been experimentally realised, thus demonstrating the potential of this device as a quantum simulator. with the possibility to create attractive on - site potentials   the scheme allows for the creation of highly entangled states and a phase with particles much more delocalised than in superfluids.
a rigorous quantum relativistic approach has been used to calculate the relationship between the decay laws of an unstable particle seen from two inertial frames moving with respect to each other. in agreement with experiment, it is found that the usual einstein s time dilation formula is rather accurate in this case.   however, small corrections to this formula were also obtained.   although the observation of these corrections is beyond the resolution of modern experiments, their presence indicates that special relativistic time dilation is not rigorously applicable to particle decays.
we demonstrate the implementation of a simple time - of - flight ( tof ) mass spectrometer with medium - mass resolution ( @xmath0 ) geared towards the demands of atomic, molecular, and chemical physics experiments. by utilizing a novel radial ion extraction scheme from a linear quadrupole trap, a device with large trap capacity and high optical access   is realized without sacrificing mass resolution.   here we describe the construction and implementation of the device as well as present representative tof spectra.   we conclude by demonstrating the flexibility of the device with proof - of - principle experiments that include the observation of molecular - ion photodissociation and the measurement of trapped - ion chemical reaction rates.
this paper presents a mechanism for the coexistence of hyperbolic and non - hyperbolic dynamics arising in a neighbourhood of a conservative bykov cycle where trajectories turn in opposite directions near the two saddle - foci.   we show that within the class of divergence - free vector fields that preserve the cycle, tangencies of the invariant manifolds of two hyperbolic saddle - foci densely occur.   the global dynamics is persistently dominated by heteroclinic tangencies and by the existence of infinitely many elliptic points coexisting with suspended hyperbolic horseshoes.   a generalized version of the cocoon bifurcations for conservative systems is obtained.
we present near infrared @xmath0, @xmath1, and @xmath2 images and @xmath3band spectroscopy in the giant h  ii region w42.   a massive star cluster is revealed ; the color  color plot and @xmath3band spectroscopic morphology of two of the brighter objects suggest the presence of young stellar objects.   the spectrum of the bright central star is similar to unobscured stars with mk spectral types of o5o6.5.   if this star is on the zero age main sequence, then the derived spectrophotometric distance is considerably smaller than previous estimates.   the lyman continuum luminosity of the cluster is a few times that of the trapezium.   the slope of the @xmath3band luminosity function is similar to that for the trapezium cluster and significantly steeper than that for the massive star cluster in m17 or the arches cluster near the galactic center.
we present status of simulations used to design a novel device for the detection of hazardous substances in the aquatic environment using neutron activation. unlike the other considered methods based on this technique we propose to use guides for neutron and gamma quanta which speeds  up and simplifies identification.   first preliminary results show that both the neutron guide and the @xmath0 ray guide increase the performance of underwater threats detection.
neutrino oscillation data had been a big surprise to theorists, and indeed they have ongoing impact on theory.   i review what the impact has been, and what measurements will have critical impact on theory in the future.   address = school of natural sciences, institute for advanced study, princeton, nj 08540, email=murayama@ias.edu, homepage = http://hitoshi.berkeley.edu, altaddress = department of physics, university of california, berkeley, ca 94720, thanks = this work was supported by the institute for advanced study, funds for natural sciences, as well as in part by the doe under contracts de - fg02 - 90er40542 and de - ac03 - 76sf00098 and in part by nsf grant phy-0098840.
a distributed classification paradigm known as _ collaborative tagging _ has been widely adopted in new web applications designed to manage and share online resources.   users of these applications organize resources ( web pages, digital photographs, academic papers ) by associating with them freely chosen text labels, or _   tags_. here we leverage the social aspects of collaborative tagging and introduce a notion of _ resource distance _ based on the collective tagging activity of users. we collect data from a popular system and perform experiments showing that our definition of distance can be used to build a weighted network of resources with a detectable community structure.   we show that this community structure clearly exposes the semantic relations among resources.   the communities of resources that we observe are a genuinely emergent feature, resulting from the uncoordinated activity of a large number of users, and their detection paves the way to mapping emergent semantics in social tagging systems.
in a thin strip of a two - dimensional semiconductor electronic system, spin - orbit coupling may be induced near both edges of the strip due to the substantial spatial variation of the confining potential in the boundary regions. in this paper   we show that, in the presence of boundary - confinement induced spin - orbit coupling, a longitudinal charge current circulating through a 2d semiconductor strip may cause _ strong _ non - equilibrium spin accumulation near both edges of the strip.   the spins will be polarized along the normal of the 2deg plane but in opposite directions at both edges of the strip.   this phenomenon is essentially a kinetic magnetoelectric effect from the theoretical points of view, but it manifests in a very similar form as was conceived in a spin hall effect.
as the complexity of deep neural networks ( dnns ) trend to grow to absorb the increasing sizes of data, memory and energy consumption has been receiving more and more attentions for industrial applications, especially on mobile devices.   this paper presents a novel structure based on functional hashing to compress dnns, namely funhashnn. for each entry in a deep net,   funhashnn uses multiple low - cost hash functions to fetch values in the compression space, and then employs a small reconstruction network to recover that entry.   the reconstruction network is plugged into the whole network and trained jointly.   funhashnn includes the recently proposed hashednets @xcite as a degenerated case, and benefits from larger value capacity and less reconstruction loss.   we further discuss extensions with dual space hashing and multi - hops. on several benchmark datasets, funhashnn demonstrates high compression ratios with little loss on prediction accuracy.
we report the discovery of the two - image gravitationally lensed quasar sdss j133222.62 + 034739.9 ( sdss j1332 + 0347 ) with an image separation of @xmath0.   this system consists of a source quasar at @xmath1 and a lens galaxy at @xmath2.   the agreement of the luminosity, ellipticity and position angle of the lens galaxy with those expected from lens model confirms the lensing hypothesis.
it is shown that the matter concentration observed through stellar motion at the galactic center ( eckart & genzel, 1997, mnras, 284, 576 and genzel et al., 1996,   apj, 472, 153 ) is consistent with a supermassive object of @xmath0 solar masses composed of self - gravitating, degenerate heavy neutrinos, as an alternative to the black hole interpretation. according to the observational data, the lower bounds on possible neutrino masses are @xmath1 kev@xmath2 for @xmath3 or @xmath4 kev@xmath2 for @xmath5, where @xmath6 is the spin degeneracy factor.   the advantage of this scenario is that it could naturally explain the low x - ray and gamma ray activity of sgr a@xmath7, i.e. the so called `` blackness problem '' of the galactic center.
the boundary sheath of a low temperature plasma comprises typically only a small fraction of its volume but is responsible for many aspects of the macroscopic behavior.   a thorough understanding of the sheath dynamics is therefore of theoretical and practical importance.   this work focusses on the so - called `` algebraic '' approach which strives to describe the electrical behavior of rf modulated boundary sheaths in closed analytical form, i.e., without the need to solve differential equations.   a mathematically simple, analytical expression for the charge - voltage relation of a sheath is presented which holds for all excitation wave forms and amplitudes and covers all regimes from the collision - less motion at low gas pressure to the collision dominated motion at gas high pressure. a comparison with the results of self - consistent particle - in - cell simulations is also presented.
i present a new fits viewer designed to explore 3d spectral line data ( in particular hi ) and assist with visual source extraction and analysis.   using the artistic software blender, frelled can visualise even large ( @xmath0600@xmath1 voxels ) data sets at high frame rates ( @xmath210 f.p.s. ) in 3d.   blender s interface enables easy navigation within the 3d environment, and the frelled scripts support world coordinate systems. a variety of tools are included to aid source extraction and analysis, including interactively masking data ( using 3d polyhedra of arbitrary complexity ), querying ned, calculating the flux in specified volumes, generating contour plots and overlaying optical data.   it includes tools to overlay n - body particle data, and multi - volume rendering is supported.   the interface is designed to make cataloguing sources as easy as possible and i show that this can be as much as a factor of 50 times faster than using other viewers.    radio lines : galaxies, galaxies : kinematics and dynamics, surveys, scientific visualization, visual analytics
we study the @xmath0 and @xmath1 signatures @xmath2 for different values of @xmath3 in the msugra model. with @xmath3 rising,   we observe a characteristic change in the shape of dilepton mass spectra in @xmath4 versus @xmath5 final states reflecting the decrease of @xmath6 branching ratio.   we also study the non msugra modifications of the cms test point lm1 with arbitrary relations among gaugino and higgsino masses. for such modifications of the msugra test point   lm1 the number of lepton events depends rather strongly on the relations among gaugino and higgsino masses and in some modifications of the test point lm1 the signatures with leptons and @xmath7 do not lead to the susy discovery and the single susy discovery signature remains the signature with @xmath8.   # 1#2#3#4#1 * # 2 * ( # 4 ) # 3
we analyze the depolarization of ultracold neutrons confined in a magnetic field configuration similar to those used in existing or proposed magneto - gravitational storage experiments aiming at a precise measurement of the neutron lifetime.   we use an extension of the semi - classical majorana approach as well as an approximate quantum mechanical analysis, both pioneered by walstrom _   et al_. [ nucl.   instr. meth.   phys.   res. a 599, 82 ( 2009 ) ].   in contrast with this previous work we do not restrict the analysis to purely vertical modes of neutron motion. the lateral motion is shown to cause the predominant depolarization loss in a magnetic storage trap.   the system studied also allowed us to estimate the depolarization loss suffered by ultracold neutrons totally reflected on a non - magnetic mirror immersed in a magnetic field.   this problem is of preeminent importance in polarized neutron decay studies such as the measurement of the asymmetry parameter @xmath0 using ultracold neutrons, and it may limit the efficiency of ultracold neutron polarizers based on passage through a high magnetic field.
the density matrix renormalization group ( dmrg ) has become a powerful numerical method that can be applied to low - dimensional strongly correlated fermionic and bosonic systems.   it allows for a very precise calculation of static, dynamical and thermodynamical properties.   its field of applicability has now extended beyond condensed matter, and is successfully used in statistical mechanics and high energy physics as well. in this article, we briefly review the main aspects of the method. we also comment on some of the most relevant applications so as to give an overview on the scope and possibilities of dmrg and mention the most important extensions of the method such as the calculation of dynamical properties, the application to classical systems, inclusion of temperature, phonons and disorder, field theory, time - dependent properties and the _ ab initio _ calculation of electronic states in molecules.
we present a detailed calculation of the rare decay @xmath0 via the quartic neutral gauge boson coupling @xmath1 in the framework of the effective lagrangian approach.   the current experimental bound on this decay mode is then used to constrain the coefficients of this coupling.   it is found that the bounds obtained in this way, of the order of @xmath2, are weaker than the ones obtained from the analysis of triple - boson production at the cern @xmath3 collider lep-2.
we demonstrate an optical fiber fault location method based on the frequency response of the modulated fiber optical backscattered signal in a steady state low - frequency step regime.   careful calibration and measurement allows for the reconstruction of the fiber transfer function, which, associated to its mathematical model, is capable of extracting the fiber characteristics.   the technique is capable of identifying non - reflective fault events in an optical fiber link and is perfectly compatible with previous methods that focus on the reflective events.   the fact that the recuperation of the complex signal is performed in the frequency domain and not via a fourier transform enables the measurements to overcome the spatial resolution limitation of fourier transform incoherent - ofdr measurements even with frequency sweep ranges down to 100 - 100000 hz.   this result is backed up by a less than 10 meters difference in fault location when compared to standard otdr measurements.
during the runs of the ps 179 experiment at lear of cern, we photographed an event of antiproton-@xmath0 absorption, with a complete @xmath1@xmath2@xmath3@xmath2e@xmath4 chain. from the vertex of the reaction   a very slow energy @xmath1 was emitted.   the @xmath1 decays into a @xmath3 and subsequently the @xmath3 decays into a positron. at the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino.   measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass : @xmath5 @xmath6 2.2 mev at a 90@xmath7 confidence level.   a statistical analysis has been performed of the factors contributing to the square value of the neutrino mass limit.   pacs.   13.20 cz, 14.60 pq, 13.25 cq    epsf.tex * *    @xmath8 @xmath9 @xmath10 @xmath11 @xmath12 @xmath13 + @xmath14 @xmath15 @xmath16 ; @xmath17, @xmath18 @xmath9 @xmath16, @xmath19 + @xmath20 @xmath21 @xmath22 @xmath23 @xmath24, @xmath25, @xmath26 + @xmath27 @xmath9 @xmath28 @xmath29 @xmath10 @xmath30 @xmath31 @xmath29 @xmath30 @xmath32 @xmath33,
the issue of using informative priors for estimation of mixtures at multiple time points is examined. several different informative priors and an independent prior are compared using samples of actual and simulated aerosol particle size distribution ( psd ) data.   measurements of aerosol psds refer to the concentration of aerosol particles in terms of their size, which is typically multimodal in nature and collected at frequent time intervals. the use of informative priors is found to better identify component parameters at each time point and more clearly establish patterns in the parameters over time. some caveats to this finding   are discussed.   ,   ,   ,
we extend the taming techniques for explicit euler approximations of stochastic differential equations ( sdes ) driven by lvy noise with super - linearly growing drift coefficients.   strong convergence results are presented for the case of locally lipschitz coefficients.   moreover, rate of convergence results are obtained in agreement with classical literature when the local lipschitz continuity assumptions are replaced by global and, in addition, the drift coefficients satisfy polynomial lipschitz continuity.   finally, we further extend these techniques to the case of delay equations.
grand canonical simulations are used to calculate adsorption isotherms of various classical gases on alkali metal and mg surfaces.   _ ab initio _ adsorption potentials and lennard - jones gas - gas interactions are used.   depending on the system, the resulting behavior can be nonwetting for all temperatures studied, complete wetting, or ( in the intermediate case ) exhibit a wetting transition.   an unusual variety of wetting transitions at the triple point is found in the case of a specific adsorption potential of intermediate strength. the general threshold for wetting near the triple point   is found to be close to that predicted with a heuristic model of cheng _ et al.   _ this same conclusion was drawn in a recent experimental and simulation study of ar on co@xmath0 by mistura _   et al. _   these results imply that a dimensionless wetting parameter @xmath1 is useful for predicting whether wetting behavior is present at and above the triple temperature.   the nonwetting / wetting crossover value found here is @xmath2 3.3.    _   pacs numbers : 64.70.fx, 68.35.rh, 68.45.gd, 82.20.wt_
the retarded green function of the electromagnetic field in spacetime of a straight thin cosmic string is found.   it splits into a geodesic part ( corresponding to the propagation along null rays ) and to the field scattered on the string. with help of the green function   the electric and magnetic fields of simple sources are constructed.   it is shown that these sources are influenced by the cosmic string through a self - interaction with their field.   the distant field of static sources is studied and it is found that it has a different multipole structure than in minkowski spacetime. on the other hand,   the string suppresses the electric and magnetic field of distant sources  the field is expelled from regions near the string.
we investigate two recent parameterizations of the galactic magnetic field with respect to their impact on cosmic nuclei traversing the field.   we present a comprehensive study of the size of angular deflections, dispersion in the arrival probability distributions, multiplicity in the images of arrival on earth, variance in field transparency, and influence of the turbulent field components. to remain restricted to ballistic deflections, a cosmic nucleus with energy @xmath0 and charge @xmath1 should have a rigidity above @xmath2 ev.   in view of the differences resulting from the two field parameterizations as a measure of current knowledge in the galactic field, this rigidity threshold may have to be increased.   for a point source search with @xmath3 ev, field uncertainties increase the required signal events for discovery moderately for sources in the northern and southern regions, but substantially for sources near the galactic disk.    astroparticle physics, magnetic fields, cosmic rays
despite decades of dedicated efforts there are still basic questions to answer with regard to supernova progenitor systems and explosion mechanisms. in particular, in the last years a number of exceptionally bright objects and extremely faint events have demonstrated an unexpected large supernova variety.   the large number of supernovae candidates at different redshifts provided by the next generation surveys, from ground and space, will allow to reach a better insight of the supernova events in all their flavours.   in particular it will be the possible to assess the systematics of type ia supernovae as distance indicator at any redshift.   the gaia astrometric mission is expected to discover a huge number of transient events, including supernovae, which will be immediately disseminated to the astronomical community by a transients alert system for a suitable follow up.
we examine the effective counterion - mediated electrostatic interaction between two like - charged dielectric cylinders immersed in a continuous dielectric medium containing neutralizing mobile counterions.   we focus on the effects of image charges induced as a result of the dielectric mismatch between the cylindrical cores and the surrounding dielectric medium and investigate the counterion - mediated electrostatic interaction between the cylinders in both limits of weak and strong electrostatic couplings ( corresponding, e.g., to systems with monovalent and multivalent counterions, respectively ).   the results are compared with extensive monte - carlo simulations exhibiting good agreement with the limiting weak and strong coupling results in their respective regime of validity.
we report on the measurement of the specific activity of @xmath0ar in natural argon.   the measurement was performed with a 2.3-liter two - phase ( liquid and gas ) argon drift chamber.   the detector was developed by the warp collaboration as a prototype detector for wimp dark matter searches with argon as a target.   the detector was operated for more than two years at laboratori nazionali del gran sasso, italy, at a depth of 3,400 m w.e.   the specific activity measured for @xmath0ar is 1.01@xmath10.02(stat)@xmath10.08(syst)bq per kg of @xmath2ar.   ,  ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,    @xmath0ar specific activity, low - background experiments, cosmogenic activation 23.40.-s, 27.40.+z, 29.40.mc, 95.35.+d
for a class of excitatory spiking neuron models with delayed feedback fed with a poisson stochastic process, it is proven that the stream of output interspike intervals can not be presented as a markov process of any order.   * keywords. * spiking neuron ; poisson stochastic process ; probability density function ; delayed feedback ; non - markov stochastic process
we investigate the fano - type spectroscopic lineshapes of the t - shape double quantum dot coupled between the conducting and superconducting electrodes and analyze their stability on a decoherence. because of the proximity effect the quantum interference patterns appear simultaneously at @xmath0, where @xmath1 is an energy of the side - attached quantum dot.   we find that decoherence gradually suppresses both such interferometric structures.   we also show that at low temperatures another tiny fano - type structure can be induced upon forming the kondo state on the side - coupled quantum dot due to its coupling to the floating lead.
a two - dimensional electron system interacting with an impurity and placed in crossed magnetic and electric fields is under investigation.   since it is assumed that an impurity center interacts as an attractive @xmath0-like potential a renormalization procedure for the retarded green s function has to be carried out. for the vanishing electric field we obtain a close analytical expression for the green s function and we find one bound state localized between landau levels.   it is also shown by numerical investigations that switching on the electric field new long - living resonance states localized in the vicinity of landau levels can be generated.
we present preliminary results from our ongoing work on integral field spectroscopy ( ifs ) of the three prototypical hii galaxies iizw70, iizw71 and izw18 @xcite.   the observations were taken with the instruments integral / wyffos at the wht ( orm, la palma ) and pmas ( calar alto, almeria ), covering a spectral range from 3600 to 6800   thus including from @xmath03727 @xmath1 up to the @xmath0@xmath06717,31 @xmath1 lines.   two - dimensional spectroscopy allows us to collect simultaneously the spectra of many different regions of an extended object, combining photometry and spectroscopy in the same data set.   the great advantage of using ifs for the investigation of galaxies is that it allows us to obtain data on the galaxy positions, velocity fields and star - formation properties all in one data cube.   our main aim is to perform a bidimensional study of the ionization structure, physical - chemical conditions and the velocity field of the ionized gas in these galaxies @xcite.   maps of the relevant emission lines and a preliminary analysis of the ionization structure are presented for iizw70.
we studied the wmap temperature anisotropy data using two different methods.   the derived signal gradient maps show regions with low mean gradients in structures near the ecliptic poles and higher gradient values in the wide ecliptic equatorial zone, being the result of non - uniform observational time sky coverage.   we show that the distinct observational time pattern present in the raw ( cleaned ) data leaves also its imprints on the composite cmb maps.   next, studying distribution of the signal dispersion we show that the north - south asymmetry of the wmap signal diminishes with galactic altitude, confirming the earlier conclusions that it possibly reveals galactic foreground effects. as based on these results  , one can suspect that the instrumental noise sky distribution and non - removed foregrounds can have affected some of the analyses of the cmb signal.   we show that actually the different characteristic axes of the cmb sky distribution derived by numerous authors are preferentially oriented towards some distinguished regions on the sky, defined by the observational time pattern and the galactic plane orientation.       cosmic microwave background   cosmology : observations  methods : data analysis
we discuss the implications of a model of noncommutative quantum mechanics where noncommutativity is extended to the phase space.   we analyze how this model affects the problem of the two - dimensional gravitational quantum well and use the latest experimental results for the energy states of neutrons in the earth s gravitational field to establish an upper bound on the fundamental momentum scale introduced by noncommutativity.   we show that the configuration space noncommutativity has, in leading order, no effect on the problem and that in the context of the model, a correction to the presently accepted value of planck s constant to @xmath0 part in @xmath1 arises.   we also study the transition between quantum and classical behaviour of particles in a gravitational quantum well and analyze how an increase in the particles mass turns the energy spectrum into a continuous one.   we consider these effects and argue that they could be tested by through experiments with atoms and fullerene - type molecules.   ps.   # 1#2#1 # 1 # 1 # 1| # 1|#1 # 1#2|#2 # 1 # 1#2__#1| # 1#2|#1__#2 # 1#2#3#4__#1
we present a detailed analysis comparing the velocity fields in molecular clouds _ and _ the atomic gas that surrounds them in order to address the origin of the gradients. to that end  , we present first - moment intensity - weighted velocity maps of the molecular clouds and surrounding atomic gas.   the maps are made from high - resolution observations and 21-cm observations from the leiden / argentine / bonn galactic @xmath0  survey.   we find that ( i ) the atomic gas associated with each molecular cloud has a substantial velocity gradient  ranging within 0.02 to 0.07 whether or not the molecular cloud itself has a substantial linear gradient.   ( ii ) if the gradients in the molecular and atomic gas were due to rotation, this would imply that the molecular clouds have less specific angular momentum than the surrounding @xmath0  by a factor of 1  6.   ( iii ) most importantly, the velocity gradient position angles in the molecular and atomic gas are generally widely separated  by as much as @xmath1 in the case of the rosette molecular cloud.   this result argues against the hypothesis that molecular clouds formed by simple top - down collapse from atomic gas.
we report on the detection of excess hard x - ray emission from the tev bl lac object mrk  421 during the historical low - flux state of the source in january 2013.   observations were conducted four times between mjd  56294 and mjd  56312 with a total exposure of 80.9ksec.   the source flux in the @xmath0kev range was nearly constant except for mjd  56307, when the average flux level increased by a factor of three. throughout the exposure,   the x - ray spectra of mrk  421 were well represented by a steep power - law model with a photon index of @xmath1, although a significant excess was noted above 20kev in the mjd  56302 data when the source was in its faintest state.   moreover, mrk  421 was detected at more than the @xmath2 level in the @xmath3kev count maps for both mjd  56307 and mjd  56302 but not during the remaining two observations.   the detected excess hard x - ray emissions connect smoothly with the extrapolation of the high - energy @xmath4-ray continuum of the blazar constrained by during the source quiescence.   these findings indicate that, while the overall x - ray spectrum of mrk  421 is dominated by the highest - energy tail of the synchrotron continuum, the variable excess hard x - ray emission above 20kev ( on the timescale of a week ) is related to the inverse compton emission component.   we discuss the resulting constraints on the variability and spectral properties of the low - energy segment of the electron energy distribution in the source.
we present results on the dynamical correlation functions of the particle - hole symmetric holstein - hubbard model at zero temperature, calculated using the dynamical mean field theory which is solved by the numerical renormalization group method.   we clarify the competing influences of the electron - electron and electron - phonon interactions particularity at the different metal to insulator transitions.   the coulomb repulsion is found to dominate the behaviour in large parts of the metallic regime. by suppressing charge fluctuations  , it effectively decouples electrons from phonons.   the phonon propagator shows a characteristic softening near the metal to bipolaronic transition but there is very little softening on the approach to the mott transition.
we use particle - in - cell ( pic ) simulations to study the nonlinear evolution of ion velocity space instabilities in an idealized problem in which a background velocity shear continuously amplifies the magnetic field.   we simulate the astrophysically relevant regime where the shear timescale is long compared to the ion cyclotron period, and the plasma beta is @xmath0.   the background field amplification in our calculation is meant to mimic processes such as turbulent fluctuations or mhd - scale instabilities.   the field amplification continuously drives a pressure anisotropy with @xmath1 and the plasma becomes unstable to the mirror and ion cyclotron instabilities. in all cases,   the nonlinear state is dominated by the mirror instability, not the ion cyclotron instability, and the plasma pressure anisotropy saturates near the threshold for the linear mirror instability.   the magnetic field fluctuations initially undergo exponential growth but saturate in a secular phase in which the fluctuations grow on the same timescale as the background magnetic field ( with @xmath2 in the secular phase ). at early times, the ion magnetic moment is well - conserved but once the fluctuation amplitudes exceed @xmath3, the magnetic moment is no longer conserved but instead changes on a timescale comparable to that of the mean magnetic field.   we discuss the implications of our results for low - collisionality astrophysical plasmas, including the near - earth solar wind and low - luminosity accretion disks around black holes.
a generalized noether s theorem and the operational determination of a physical geometry in quantum physics are used to motivate a quantum geometry consisting of relations between quantum states that are defined by a universal group. making these relations   dynamical implies the non local effect of the fundamental interactions on the wave function, as in the aharonov - bohm effect and its generalizations to non abelian gauge fields and gravity.   the usual space - time geometry is obtained as the classical limit of this quantum geometry using the quantum state space metric.    _ paper presented at the xxiii international colloquium on group theoretical methods in physics, dubna, russia, 30 july - 05 august, 2000, quant - ph/0012011_.
we propose a technique of compensating the spurious reflections implied by the multiple - scattering ( ms ) method, commonly used for analyzing finite photonic crystal ( pc ) systems, to obtain exact values of characteristic parameters, such as reflection and transmission coefficients, of pc functional elements. rather than a modification of the ms computational algorithm,   our approach involves postprocessing of results obtained by the ms method.   we derive analytical formulas for the fields excited in a finite system, taking explicitly into account the spurious reflections occurring at the artificial system boundaries.   the intrinsic parameters of the investigated functional element are found by fitting the results of ms simulations to those obtained from the formulas derived.   devices linked with one and two semi - infinite waveguides are analyzed explicitly ; possible extensions of the formalism to more complex circuits are discussed as well.   the accuracy of the proposed method is tested in a number of systems ; the results of our calculations prove to be in good agreement with those obtained independently by other authors.
daily observations of the binary x - ray pulsar gx  1 + 4 were made with the _ rossi x - ray timing explorer _ ( _ rxte _ ) satellite between 1997 may 1620 as part of a four - month monitoring program. on may   17 the sharp dips normally observed in the lightcurve were all but absent, resulting in a pulse fraction @xmath0 instead of the more typical value of @xmath1 measured before and after  . also observed was a dramatic hardening of the 240  kev phase - averaged spectrum.   the power - law photon index was @xmath2, whereas values of 1.62.0 are more typical. in terms of a comptonization continuum component, the optical depth for scattering was @xmath3, with 46 the usual range for _ rxte _ spectra @xcite.   pulse - phase spectrosopy indicates that @xmath4 is decreased relative to the phase - averaged value around the primary minimum, where an increase is normally observed.   the reduced depth of the dip is interpreted as disruption of the accretion column, and the accompanying spectral variation suggests a substantially different accretion regime than is usual for this source.
we perform the most attractive channel ( mac ) analysis in the top mode standard model with tev - scale extra dimensions, where the standard model gauge bosons and the third generation of quarks and leptons are put in @xmath0 dimensions.   in such a model, bulk gauge couplings rapidly grow in the ultraviolet region. in order to make the scenario viable,   only the attractive force of the top condensate should exceed the critical coupling, while other channels such as the bottom and tau condensates should not.   we then find that the top condensate can be the mac for @xmath1, whereas the tau condensation is favored for @xmath2.   the analysis for @xmath3 strongly depends on the regularization scheme.   we predict masses of the top @xmath4 and the higgs @xmath5, @xmath6 gev and @xmath7 gev for @xmath1, based on the renormalization group for the top yukawa and higgs quartic couplings with the compositeness conditions at the scale where the bulk top condenses.   the higgs boson in such a characteristic mass range will be immediately discovered in @xmath8 once the lhc starts.
joint optimization of nonlinear precoders and receive filters is studied for both the uplink and downlink in a cellular system. for the uplink,   the base transceiver station ( bts ) receiver implements successive interference cancellation, and for the downlink, the bts station pre - compensates for the interference with tomlinson - harashima precoding ( thp ).   convergence of alternating optimization of receivers and transmitters in a single cell is established when filters are updated according to a minimum mean squared error ( mmse ) criterion, subject to appropriate power constraints. _   adaptive _ algorithms are then introduced for updating the precoders and receivers in the absence of channel state information, assuming time - division duplex transmissions with channel reciprocity. instead of estimating the channels, the filters are directly estimated according to a least squares criterion via bi - directional training :   uplink pilots are used to update the feedforward and feedback filters, which are then used as interference pre - compensation filters for downlink training of the mobile receivers.   numerical results show that nonlinear filters can provide substantial gains relative to linear filters with limited forward - backward iterations.
this paper studies multistep methods for the integration of reversible dynamical systems, with particular emphasis on the planar kepler problem.   it has previously been shown by cano & sanz - serna that reversible linear multisteps for first - order differential equations are generally unstable. here, we report on a subset of these methods  the _ zero - growth methods _  that evade these instabilities.   we provide an algorithm for identifying these rare methods. we find and study all zero - growth, reversible multisteps with six or fewer steps.   this select group includes two well - known second - order multisteps ( the trapezoidal and explicit midpoint methods ), as well as three new fourth - order multisteps   one of which is explicit.   variable timesteps can be readily implemented without spoiling the reversibility.   tests on keplerian orbits show that these new reversible multisteps work well on orbits with low or moderate eccentricity, although at least 100 steps / radian are required for stability.   # 1#2    # 1to 0pt#1
niobium - based superconducting radio frequency ( srf ) cavity performance is sensitive to localized defects that give rise to quenches at high accelerating gradients. in order to identify these material defects on bulk nb surfaces at their operating frequency and temperature, it is important to develop a new kind of wide bandwidth microwave microscopy with localized and strong rf magnetic fields. by taking advantage of write head technology widely used in the magnetic recording industry,   one can obtain @xmath0200 @xmath1 rf magnetic fields, which is on the order of the thermodynamic critical field of nb, on sub - micron length scales on the surface of the superconductor.   we have successfully induced the nonlinear meissner effect via this magnetic write head probe on a variety of superconductors.   this design should have a high spatial resolution and is a promising candidate to find localized defects on bulk nb surfaces and thin film coatings of interest for accelerator applications.    harmonic generation, microwave microscope, magnetic write head, nonlinear meissner effect, near - field, rf superconductivity.
the possible normal modes of vibration of a nearly spherical virus particle are discussed.   two simple models for the particle are treated, a liquid drop model and an elastic sphere model.   some estimates for the lowest vibrational frequency are given for each model.   it is concluded that this frequency is likely to be of the order of a few ghz for particles with a radius of the order of @xmath0.
one of the central conceptual problems in high @xmath0 superconductivity is to reconcile the abundant evidence for stripe - like physics at ` short'distances with the equally convincing evidence for bcs - like physics at large distance scales ( the ` nodal fermions').   our central hypothesis is that the duality notion applies : the superconductor should be viewed as a condensate of topological excitations associated with the fully ordered stripe phase.   as we will argue, the latter are not only a form of ` straightforward'spin and charge order but also involve a form of ` hidden'or ` topological'long range order which is also responsible for the phenomenon of spin - charge separation in 1 + 1d.   the topological excitation associated with the destruction of this hidden order is of the most unusual kind.   we suggest that the associated disorder field theory has a geometrical, gravity like structure concurrent with topological phases with no precedent elsewhere.
the streamwise and transverse velocities are measured simultaneously in isotropic grid turbulence at relatively high reynolds numbers, re@xmath0330. using a conditional averaging technique, we extract typical intermittency patterns, which are consistent with velocity profiles of a model for a vortex tube, i.e., burgers vortex.   the radii of the vortex tubes are several of the kolmogorov length regardless of the reynolds number. using the distribution of an interval between successive enhancements of a small - scale velocity increment, we study the spatial distribution of vortex tubes.   the vortex tubes tend to cluster together.   this tendency is increasingly significant with the reynolds number. using statistics of velocity increments  , we also study the energetical importance of vortex tubes as a function of the scale.   the vortex tubes are important over the background flow at small scales especially below the taylor microscale. at a fixed scale,   the importance is increasingly significant with the reynolds number.
in this paper we give a detailed analysis of deterministic and randomized algorithms that enumerate any number of irreducible polynomials of degree @xmath0 over a finite field and their roots in the extension field in quasilinear where @xmath1 is the size of the output.   ] time cost per element.   our algorithm is based on an improved algorithm for enumerating all the lyndon words of length @xmath0 in linear delay time and the known reduction of lyndon words to irreducible polynomials.
we find that anti - de sitter ( ads ) spacetime with a nontrivial linear dilaton field is an exact solution in the effective action of the string theory, which is described by gravity with the gauss - bonnet curvature terms coupled to a dilaton field in the string frame without a cosmological constant.   the ads radius is determined by the spacetime dimensions and the coupling constants of curvature corrections.   we also construct the asymptotically ads black hole solutions with a linear dilaton field numerically.   we find these ads black holes for hyperbolic topology and in dimensions higher than four.   we discuss the thermodynamical properties of those solutions. extending the model to the case with the even - order higher lovelock curvature terms  , we also find the exact ads spacetime with a nontrivial dilaton.   we further find a cosmological solution with a bounce of three - dimensional space and a solitonic solution with a nontrivial dilaton field, which is regular everywhere and approaches an asymptotically ads spacetime.
we present ground - based optical observations of starting 1.6 hours after the burst, as well as subsequent very large array ( vla ) and _ hubble space telescope _ ( hst ) observations.   the optical afterglow of is one of the faintest afterglows detected to date, and it exhibits a relatively rapid decay, @xmath0, followed by further steepening.   in addition, a weak radio source was found coincident with the optical afterglow.   the hst observations reveal that a positionally coincident host galaxy must be the faintest host to date, @xmath1 mag.   the afterglow observations can be explained by several models requiring little or no extinction within the host galaxy, @xmath2 mag.   these observations have significant implications for the statistics of the so - called dark bursts ( bursts for which no optical afterglow is detected ), which are usually attributed to dust extinction within the host galaxy.   the faintness and relatively rapid decay of the afterglow of, combined with the low inferred extinction indicate that some dark bursts are intrinsically dim and not dust obscured.   thus, the diversity in the underlying properties of optical afterglows must be observationally determined before substantive inferences can be drawn from the statistics of dark bursts.   # 1#2#3#1@xmath3#2@xmath4#3@xmath5 # 1#2#3@xmath6
in this work it is studied the hopfield fermionic spin glass model which allows interpolating from trivial randomness to a highly frustrated regime.   therefore, it is possible to investigate whether or not frustration is an essential ingredient which would allow this magnetic disordered model to present naturally inverse freezing by comparing the two limits, trivial randomness and highly frustrated regime and how different levels of frustration could affect such unconventional phase transition.   the problem is expressed in the path integral formalism where the spin operators are represented by bilinear combinations of grassmann variables.   the grand canonical potential is obtained within the static approximation and one - step replica symmetry breaking scheme. as a result,   phase diagrams temperature _ versus _ the chemical potential are obtained for several levels of frustration.   particularly, when the level of frustration is diminished, the reentrance related to the inverse freezing is gradually suppressed.
the antiferromagnetic correlation plays an important role in high - t@xmath0 superconductors. considering this effect,   the magnetic excitations in n - type cuprates near the optimal doping are studied within the spin density wave description.   the magnetic excitations are commensurate in the low energy regime and further develop into spin wave - like dispersion at higher energy, well consistent with the inelastic neutron scattering measurements.   we clearly demonstrate that the commensurability originates from the band splitting and fermi surface topology.   the commensurability is a normal state property, and has nothing to do with d - wave superconductivity.   the distinct behaviors of magnetic excitation between the n - type and p - type cuprates are further discussed.   our results strongly suggest the essential role of antiferromagnetic correlations in the cuprates.
a high - finesse fabry - perot cavity with a frequency - doubled continuous wave green laser ( 532  nm ) has been built and installed in hall a of jefferson lab for high precision compton polarimetry.   the infrared ( 1064  nm ) beam from a ytterbium - doped fiber amplifier seeded by a nd : yag nonplanar ring oscillator laser is frequency doubled in a single - pass periodically poled mgo : linbo@xmath0 crystal.   the maximum achieved green power at 5 w infrared pump power is 1.74 w with a total conversion efficiency of 34.8%. the green beam is injected into the optical resonant cavity and enhanced up to 3.7  kw with a corresponding enhancement of 3800.   the polarization transfer function has been measured in order to determine the intra - cavity circular laser polarization within a measurement uncertainty of 0.7%.   the prex experiment at jefferson lab used this system for the first time and achieved 1.0% precision in polarization measurements of an electron beam with energy and current of 1.06  gev and 50  @xmath1a.   +    compton polarimetry, fabry - perot cavity, laser polarization, polarized electron beam
the power spectra of 457 short batse bursts were analyzed, focusing on the @xmath0 lightcurves tails in the low energy bands. using mc simulations,   22 grbs were identified with unusually high harmonic power above @xmath1.   the sky distribution of these bursts shows an extraordinarily strong dipole moment with a @xmath2 significance.
in this course we give a selfcontained introduction to the quantum field theory for trapped atomic gases, using functional methods throughout.   we consider both equilibrium and nonequilibrium phenomena. in the equilibrium case  , we first derive the appropriate hartree - fock theory for the properties of the gas in the normal phase.   we then turn our attention to the properties of the gas in the superfluid phase, and present a microscopic derivation of the bogoliubov and popov theories of bose - einstein condensation and the bardeen - cooper - schrieffer theory of superconductivity.   the former are applicable to trapped bosonic gases such as rubidium, lithium, sodium and hydrogen, and the latter in particular to the fermionic isotope of atomic lithium. in the nonequilibrium case, we discuss various topics for which a field - theoretical approach is especially suited, because they involve physics that is not contained in the gross - pitaevskii equation.   examples are quantum kinetic theory, the growth and collapse of a bose condensate, the phase dynamics of bosonic and fermionic superfluids, and the collisionless collective modes of a bose gas below the critical temperature.
we find a further class of exact solutions to the lighthill  whitham  richards   payne ( lwrp ) traffic flow equations. as before, using two consecutive lagrangian transformations, a linearization is achieved.   next, depending on the initial density, we either obtain exact formulae for the dependence of the car density and velocity on @xmath0, or else, failing that, the same result in a parametric representation.   the calculation always involves two possible factorizations of a consistency condition. both must be considered. in physical terms  , the lineup usually separates into two offshoots at different velocities.   each velocity soon becomes uniform.   this outcome in many ways resembles not only rowlands, infeld and skorupski 2013 _ j. phys.   a : math.   theor. _ * 46 * 365202 ( part i ) but also the two soliton solution to the korteweg  de vries equation.   this paper can be read independently of part i. this explains unavoidable repetitions.   possible uses of both papers in checking numerical codes are indicated at the end. since lwrp, numerous more elaborate models, including multiple lanes, traffic jams, tollgates etc. abound in the literature. however, we present an exact solution.   these are few and far between, other then found by inverse scattering.   the literature for various models, including ours, is given.   the methods used here and in part i may be useful in solving other problems, such as shallow water flow.
based on the results of numerical modeling, it is shown that dipole - dipole interactions among atoms in the active medium influences strongly the character of the associated superradiation.   the main effect is to make the nuclear subsystem behave chaotically.   its strength increases with the atom density, and leads to the suppression of distant collective correlations and superradiation. near correlations between the atoms   are established, causing a confinement effect : a shielding of radiation in the active medium.    _   keywords_:superradiation, superfluorescence, dipole - dipole interaction, coherent radiation
we report the results of a survey for novae in and between the galaxies of the fornax cluster.   our survey provides strong evidence that intracluster novae exist and that they provide a useful, independent measure of the intracluster light in fornax.   we discovered six strong nova candidates in six distinct epochs spanning eleven years from 1993 to 2004.   the data were taken with the 4 m and the 1.5 m telescopes at ctio.   the spatial distribution of the nova candidates is consistent with @xmath016 - 41% of the total light in the cluster being in the intracluster light, based on the ratio of the number of novae we discovered in intracluster space over the total number of novae discovered plus a simple completeness correction factor.   this estimate is consistent with independent measures of intracluster light in fornax and virgo using intracluster planetary nebulae.   the accuracy of the intracluster light measurement improves with each survey epoch as more novae are discovered.
the forest has emerged as one of the few systems capable of probing small - scale structure at high-@xmath0 with high precision. in this   talk i highlight two areas in which the forest is shedding light on fundamental questions in cosmology, one speculative and one which should be possible in the near future.
we present a novel model to calculate vertical transport properties such as conductance and current in unintentionally disordered double barrier gaas - al@xmath0ga@xmath1as heterostructures.   the source of disorder comes from interface roughness at the heterojunctions ( lateral disorder ) as well as spatial inhomogeneities of the al mole fraction in the barriers ( compositional disorder ).   both lateral and compositional disorder break translational symmetry along the lateral direction and therefore electrons can be scattered off the growth direction. the model correctly describe channel mixing due to these elastic scattering events. in particular, for realistic degree of disorder, we have found that the effects of compositional disorder on transport properties are negligible as compared to the effects due to lateral disorder.
we study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter ( cdm ) and baryonic structures within the flat @xmath0cdm model, using both numerical simulations and a semi - analytical linear technique, with the aim of understanding the neutrinos clustering properties for direct detection purposes. in a comparative analysis  , we find that the linear technique systematically underestimates the amount of clustering for a wide range of cdm halo and neutrino masses.   this invalidates earlier claims of the technique s applicability.   we then compute the approximate phase space distribution of relic neutrinos in our neighbourhood at earth, and estimate the large scale neutrino density contrasts within the local greisen  zatsepin  kuzmin zone. with these findings  , we discuss the implications of gravitational neutrino clustering for scattering - based detection methods, ranging from flux detection via cavendish - type torsion balances, to target detection using accelerator beams and cosmic rays. for emission spectroscopy via resonant annihilation of extremely energetic cosmic neutrinos on the relic neutrino background, we give new estimates for the expected enhancement in the event rates in the direction of the virgo cluster.   desy 04 - 147
hard - soft bilayers are analogous to prototype exchange - biased ferromagnetic -antiferromagnetic systems as the minor loop of the soft layer is biased by the hard and furthermore they offer bias layer tunability. in sputtered copt / co hard - soft bilayers we demonstrate that the exchange bias field shows a linear dependence on the hard layer magnetization, while the coercivity shows a quadratic dependence.   analysis of the minor hysteresis loop features supported by monte - carlo simulations provide clear evidence that the coercivity of the soft layer is mainly determined by the tunable randomness of the domain state of the hard layer.
in this report we present the temperature evolution of magnetic coercivity of graphene oxide ( go ) and reduced graphene oxide ( rgo ).   we report an anamolous decrease in coercivity of go and rgo with decreasing temperature.   we could explain this anamolous behavior invoking the inherent presence of ripple in graphene.   we observe antiferromagnetic and ferromagnetic behavior at room temperature for go and rgo respectively, but at low temperatures both shows paramagnetic behavior.
random walks are basic diffusion processes on networks and have applications in, for example, searching, navigation, ranking, and community detection.   recent recognition of the importance of temporal aspects on networks spurred studies of random walks on temporal networks.   here we theoretically study two types of event - driven random walks on a stochastic temporal network model that produces arbitrary distributions of interevent times. in the so - called active random walk,   the interevent time is reinitialized on all links upon each movement of the walker. in the so - called passive random   walk, the interevent time is reinitialized only on the link that has been used the last time, and it is a type of correlated random walk.   we find that the steady state is always the uniform density for the passive random walk.   in contrast, for the active random walk, it increases or decreases with the node s degree depending on the distribution of interevent times.   the mean recurrence time of a node is inversely proportional to the degree for both active and passive random walks.   furthermore, the mean recurrence time does or does not depend on the distribution of interevent times for the active and passive random walks, respectively.
we report simulations of the gas flow in the gravitational potential of the cobe nir bulge and disk.   these models lead to four  armed spiral structure between corotation of the bar and the sun, in agreement with the observed spiral arm tangents.   the 3-kpc - arm is identified with one of the arms emanating from the ends of the bar.
we suggest that jovian planets will survive the late stages of stellar evolution, and that white dwarfs will retain planetary systems in wide orbits ( @xmath0au ). utilising evolutionary models for jovian planets,   we show that infra - red imaging with 8 m class telescopes of suitable nearby white dwarfs should allow us to resolve and detect companions @xmath1.   detection of massive planetary companions to nearby white dwarfs would prove that such objects can survive the final stages of stellar evolution, place constraints on the frequency of main sequence stars with planetary systems dynamically similar to our own and allow direct spectroscopic investigation of their composition and structure.   stars : white dwarfs  planets : extra - solar
intrinsic bilayer graphene is a gapless semimetal. under the application of a bias field it becomes a semiconductor with a direct band gap that is proportional to the applied field. under a layer - asymmetric strain ( where the upper layer undergoes compression and lower layer tension or visa - versa ) we find that the band gap of a biased bilayer graphene ribbon becomes indirect and, for higher strains, becomes negative returning the material its original semimetal state. as a result  , the conductivity of the ribbon increases and can be almost an order of magnitude larger that of the intrinsic unbiased material - a change that can be induced with a strain of only @xmath0.   the conductivity is proportional to the applied strain and the magnitude of the effect is tunable with the bias field.   such layer - asymmetric strains can be achieved by bending, with forces on the order of @xmath1 resulting in a layer - asymmetric strain of @xmath2.   this new electromechanical effect has a wide potential for application in the areas of nano - force microscopy and pressure sensing on the atomic scale.
among the distinguishing characteristics of the remarkable hot r coronae borealis star dy cen, which was recently found to be a spectroscopic binary, is the presence of nebular forbidden lines in its optical spectrum.   a compilation of photometry from 1970 to the present suggests that the star has evolved to higher effective temperatures.   comparison of spectra from 2010 with earlier spectra show that between 2003 and 2010, the 6717 and 6730   emission lines of  underwent a dramatic change in their fluxes suggesting an increase in the nebula s electron density of 290 @xmath0 to 3140 @xmath0 from 1989 to 2010 while the stellar temperature increased from 19500 k to 25000 k. the nebular radius is about 0.02 pc, 60000 times bigger than the semimajor axis of dy cen binary system.   rapid changes of stellar temperature and its response by the nebula demonstrate stellar evolution in action.       star : individual : dy cen : variables : rcb type : nebula, stellar evolution
this paper discusses consistent flag bicolorings of maps and maniplexes, in their own right and as generalizations of orientations and pseudo - orientations.   furthermore, a related doubling concept is introduced, and relationships between these ideas are explored.   = 5    * flag bicolorings, pseudo - orientations, and double covers of maps. *    hiroki koike + ` yanorado@gmail.com ` + institute andrej marui + university of primorska + koper, slovenia +    daniel pellicer + ` pellicer@matmor.unam.mx ` + centro de ciencias matemticas + universidad nacional autnoma de mxico + morelia, mexico +    miguel raggi + ` mraggi@gmail.com ` + centro de ciencias matemticas + universidad nacional autnoma de mxico + morelia, mexico +    steve wilson + ` stephen.wilson@nau.edu ` + department of mathematics and statistics + northern arizona university + flagstaff, usa +
in this work we address the impact of a cubic term addition to the ginzburg - landau mean - field potential, and study the consequences on the description of first order phase transitions in superconductors.   constraints are obtained from experiment and used to assess consequences on topological defect creation.   no fundamental changes in either the kibble - zurek or hindmarsh - rajantie predictions are found.    0.5 cm    0.2 cm    0.2 cm    0.5 cm
we provide a comprehensive, up - to - date analysis of possible new physics contributions to the mass difference @xmath0 in @xmath1-@xmath2 mixing.   we consider the most general low energy effective hamiltonian and include leading order qcd running of effective operators.   we then explore an extensive list of possible new physics models that can generate these operators, which we organize as including extra fermions, extra gauge bosons, extra scalars, extra space dimensions and extra symmetries.   for each model we place restrictions on the allowed parameter space using the recent evidence for observation of @xmath3 meson mixing. in many scenarios,   we find strong constraints that surpass those from other search techniques and provide an important test of flavor changing neutral currents in the up - quark sector.   we also review the recent babar and belle findings, and describe the current status of the standard model predictions of @xmath1-@xmath2 mixing.
we study the orbital architecture of multi - planet systems detected by the transit mission using n - body simulations, focussing on the orbital spacing between adjacent planets in systems showing four or more transiting planets.   we find that the observed spacings are tightly clustered around @xmath0 mutual hill radii, when transit geometry and sensitivity limits are accounted for. in comparison,   dynamical integrations reveal that the minimum spacing required for systems of similar masses to survive dynamical instability for as long as a billion years is, @xmath1 if all orbits are circular and coplanar, and @xmath2 if planetary orbits have eccentricities @xmath3 ( a value suggested by studies of planet transit - time - variations )  . this apparent coincidence, between the observed spacing and the theoretical stability threshold, leads us to propose that typical planetary systems were formed with even tighter spacing, but most, except for the widest ones, have undergone dynamical instability, and are pared down to a more anemic version of their former selves, with fewer planets and larger spacings.   so while the high multiple systems ( five or more transiting planets ) are primordial systems that remain stable, the single or double planetary systems, abundantly discovered by the mission, may be the descendants of more closely packed high multiple systems.   if this hypothesis is correct, we infer that the formation environment of systems should be more dissipative than that of the terrestrial planets.
we explore the adsorption of mos@xmath0  on a range of metal substrates by means of first - principles density functional theory calculations. including van der waals forces in the density   functional is essential to capture the interaction between mos@xmath0  and a metal surface, and obtain reliable interface potential steps and schottky barriers.   special care is taken to construct interface structures that have a mismatch between the mos@xmath0  and the metal lattices of @xmath11%.   mos@xmath0  is chemisorbed on the early transition metal ti, which leads to a strong perturbation of its ( electronic ) structure and a pinning of the fermi level 0.54 ev below the mos@xmath0  conduction band due to interface states.   mos@xmath0  is physisorbed on au, where the bonding hardly perturbs the electronic structure.   the bonding of mos@xmath0  on other metals lies between these two extreme cases, with interface interactions for the late 3d transition metals co, ni, cu and the simple metal mg that are somewhat stronger than for the late 4d/5d transition metals pd, ag, pt and the simple metal al.   even a weak interaction, such as in the case of al, gives interface states, however, with energies inside the mos@xmath0  band gap, which pin the fermi level below the conduction band.
the interplay between the coupling of an interacting quantum dot to a conduction band and its connection to localized levels has been studied in a triple quantum dot arrangement.   the electronic dicke effect, resulting from quasi - resonant states of two side - coupled non - interacting quantum dots, is found to produce important effects on the kondo resonance of the interacting dot.   we study in detail the kondo regime of the system by applying a numerical renormalization group analysis to a finite-@xmath0 multi - impurity anderson hamiltonian model.   we find an extreme narrowing of the kondo resonance, as the single - particle levels of the side dots are tuned towards the fermi level and  squeeze " the kondo resonance, accompanied by a strong drop in the kondo temperature, due to the presence of a supertunneling state.   further, we show that the kondo temperature _ vanishes _ in the limit of the dicke effect of the structure. by analyzing the magnetic moment and entropy of the three - dot cluster versus temperature, we identify a different _ local _ singlet that competes with the kondo state, resulting in the eventual suppression of the kondo temperature and strongly affecting the spin correlations of the structure.   we further show that system asymmetries in couplings, level structure or due to coulomb interactions, result in interesting changes in the spectral function near the fermi level.   these strongly affect the kondo temperature and the linear conductance of the system.
we study strategies for establishing long - distance entanglement in quantum networks. specifically, we consider networks consisting of regular lattices of nodes, in which the nearest neighbors share a pure, but non - maximally entangled pair of qubits. we look for strategies that use local operations and classical communication   we compare the classical entanglement percolation protocol, in which every network connection is converted with a certain probability to a singlet, with protocols in which classical entanglement percolation is preceded by measurements designed to transform the lattice structure in a way that enhances entanglement percolation.   we analyze five examples of such comparisons between protocols and point out certain rules and regularities in their performance as a function of degree of entanglement and choice of operations.
a weak galerkin ( wg ) finite element method for solving the stationary stokes equations in two- or three- dimensional spaces by using discontinuous piecewise polynomials is developed and analyzed.   the variational form we considered is based on two gradient operators which is different from the usual gradient - divergence operators.   the wg method is highly flexible by allowing the use of discontinuous functions on arbitrary polygons or polyhedra with certain shape regularity.   optimal - order error estimates are established for the corresponding wg finite element solutions in various norms.   numerical results are presented to illustrate the theoretical analysis of the new wg finite element scheme for stokes problems.   weak galerkin finite element methods, weak gradient, stokes equations, polytopal meshes.   primary, 65n30, 65n15, 65n12, 74n20 ; secondary, 35b45, 35j50, 35j35
we study spatial embeddings of random graphs in which nodes are randomly distributed in geographical space.   we let the edge probability between any two nodes to be dependent on the spatial distance between them and demonstrate that this model captures many generic properties of social networks, including the `` small - world '' properties, skewed degree distribution, and most distinctively the existence of community structures.    * msc classifications : * 91d30, 90b10, 82b99.   * keywords : * social networks, small world, spatial model, community structure, homophily.
the * ka*rlsruhe * tri*tium * n*eutrino experiment ( katrin ) aims to measure the mass of electron neutrinos from beta - decay of tritium with an unprecedented sensitivity of @xmath0 improving present limits by one order of magnitude.   the decay electrons will originate from a @xmath1 long windowless, gaseous tritium source.   super - conducting magnets guide the electrons through differential and cryogenic pumping sections to the electro - static tandem spectrometer ( mac - e - filter ), where the kinetic energy will be measured.   the experiment is presently being built at the _ forschungszentrum karlsruhe _ by an international collaboration of more than 120 scientists.   the largest component, the @xmath2 main spectrometer, was delivered end of 2006 and first commissioning tests have been performed.   this presentation describes the goals and technological challenges of the experiment and reports on the progress in commissioning first major components.   the start of first measurements is expected in 2012.
progress in the effective field theory of two and three nucleon systems is sketched, concentrating mainly on the low energy version in which pions are integrated out as explicit degrees of freedom.   examples given are : the extraction of nucleon polarisabilities from deuteron compton scattering at very low energies ; the energy dependence of the nucleon polarisabilities ; three body forces and the triton ; and @xmath0 partial waves at momenta below the pion cut.   nucl - th/0108060 + tum - t39 - 01 - 21 + 26th august 2001    * harald w.  griehammer *     _ institut fr theoretische physik ( t39 ), physik - department, + technische universitt mnchen, d-85747 garching, germany _
grb 120308a, a long duration @xmath0ray burst detected by _   swift _, was distinguished by a highly - polarized early optical afterglow emission that strongly suggests an ordered magnetic field component in the emitting region. in this work we model the optical and x - ray emission in the reverse and forward shock scenario and   show that the strength of the magnetic field in reverse shock region is @xmath1 times stronger than that in the forward shock region.   consequently the outflow powering the highly - polarized reverse shock optical emission was mildly - magnetized at a degree @xmath2 a few percent. considering the plausible magnetic energy dissipation in both the acceleration and prompt emission phases of the gamma - ray burst ( grb ) outflow, the afterglow data of grb 120308a provides us the compelling evidence that at least for some grbs a non - ignorable fraction of the energy was released in the form of poynting - flux, confirming the finding firstly made in the reverse - forward shock emission modeling of the optical afterglow of grb 990123 ( fan et al.   2002 ; zhang et al.   2003 ).
we consider evolution of metal - enriched gas exposed to a superposition of time - dependent radiation field of a nearby starburst galaxy and nearly invariant ( on timescales 100 myr ) extragalactic ionization background. within nonequilibrium ( time - dependent )   photoionization models we determine ionization fraction of the ovi ion commonly observed in galactic circumference.   we derive then conditions for ovi to appear in absorptions in extended galactic haloes depending on the galactic mass and star formation rate.   we have found that the maximum ovi fraction can reach @xmath0 under combined action of the galactic and the extragalactic ionizing radiation fields.   we conclude that soft x - ray emission with @xmath1  ev from the stellar population of central starforming galaxies is the main source of such a high fraction of ovi.   this circumstance can explain high column densities @xmath2  @xmath3 observed in the haloes of starforming galaxies at low redshifts @xcite _ even _ for a relatively low ( @xmath4 ) metallicity. as a result, the requirements to the sources of oxygen in the extended haloes relax to a reasonably conservative level.   we show that at @xmath5 ionization kinetics of oxygen in a relatively dense plasma @xmath6 @xmath7 of outer halo exposed to a low extragalactic ionizing flux is dominated by nonequilibrium effects.       galaxies : evolution  haloes  starburst  theory  diffuse radiation  intergalactic medium  quasars : general  absorption lines  physical data and processes : atomic processes
a new monte - carlo based uncertainty analysis is introduced to quantitatively determine the predictive ability of qcd sum rules.   a comprehensive analysis of ground state @xmath0-meson and nucleon spectral properties is performed.   many of the findings contradict the conventional wisdom of both practitioners and skeptics alike.   associations between the phenomenological fit parameters are particularly interesting as they reveal how the sum rules resolve the spectral properties.   the use of derivative sum rules for the determination of @xmath0-meson spectral properties is shown to be a very unfavorable approach.   most prior nucleon sum rule analyses are based on a sum rule which is found to be invalid ; the results are suspect, and should be reevaluated.   the `` ioffe formula '', argued by many to qualitatively encapsulate a description of the nucleon mass in terms of the chiral symmetry breaking order parameter @xmath1 is misleading at best.   qcd sum rules are found to be self - consistent without contributions from direct instantons.   this implies that instanton effects are adequately accounted for in the nonperturbative vacuum condensates.   this in - depth examination of qcd sum rule self consistency paints a favorable picture for further quantitative refinements of the qcd sum rule approach.
the spectrum and wave function of helical edge modes in @xmath0 topological insulator are derived on a square lattice using bernevig - hughes - zhang ( bhz ) model.   the bhz model is characterized by a `` mass '' term @xmath1.   a topological insulator realizes when the parameters @xmath2 and @xmath3 fall on the regime, either @xmath4 or @xmath5. at @xmath6, which separates the cases of positive and negative ( quantized ) spin hall conductivities,   the edge modes show a corresponding change that depends on the edge geometry. in the @xmath7-edge,   the spectrum of edge mode remains the same against change of @xmath8, although the main location of the mode moves from the zone center for @xmath9, to the zone boundary for @xmath10 of the 1d brillouin zone. in the @xmath11-edge geometry,   the group velocity at the zone center changes sign at @xmath12 where the spectrum becomes independent of the momentum, _ i.e. _ flat, over the whole 1d brillouin zone.   furthermore, for @xmath13, the edge mode starting from the zone center vanishes in an intermediate region of the 1d brillouin zone, but reenters near the zone boundary, where the energy of the edge mode is marginally below the lowest bulk excitations. on the other hand,   the behavior of reentrant mode in real space is indistinguishable from an ordinary edge mode.
we consider the general problem of estimating the inflight lisa noise power spectra and cross - spectra, which are needed for detecting and estimating the gravitational wave signals present in the lisa data.   for the lisa baseline design and in the long wavelength limit, we bound the error on all spectrum estimators that rely on the use of the fully symmetric sagnac combination ( @xmath0 ).   this procedure avoids biases in the estimation that would otherwise be introduced by the presence of a strong galactic background in the lisa data.   we specialize our discussion to the detection and study of the galactic white dwarf - white dwarf binary stochastic signal.
a crossover from @xmath0 to @xmath1, and then back to @xmath0-dimensional critical behavior is argued to be a generic feature characterizing ordering in a @xmath0-dimensional superlattice composed of atomically _ thick _ films of two ferromagnets.   the crossover leads to anomalous changes in the amplitudes of critical singularities. in @xmath2 heisenberg and   @xmath3 superlattices large scale critical fluctuations persist over a wide temperature range.    #
we reconsider the structure - based route to coarse graining in which the coarse - grained model is defined in such a way to reproduce some distributions functions of the original system as accurately as possible.   we consider standard expressions for pressure and chemical potential applied to this family of coarse - grained models with density - dependent interactions and show that they only provide approximations to the pressure and chemical potential of the underlying original system.   these approximations are then carefully compared in two cases : we consider a generic microscopic system in the low - density regime and polymer solutions under good - solvent conditions.   moreover, we show that the state - dependent potentials depend on the ensemble in which they have been derived.   therefore, care must be used in applying canonical state - dependent potentials to predict phase lines, which is typically performed in other ensembles.
the aim of this paper is to provide a logic - based conceptual analysis of the twin paradox ( twp ) theorem within a first - order logic framework.   a geometrical characterization of twp and its variants is given.   it is shown that twp is not logically equivalent to the assumption of the slowing down of moving clocks, and the lack of twp is not logically equivalent to the newtonian assumption of absolute time.   the logical connection between twp and a symmetry axiom of special relativity is also studied.
the measurement of charged particle spectra in heavy ion collisions is a way to study properties of hot and dense matter created in these interactions.   the centrality dependence of the spectral shape is an important tool to understand the energy loss mechanism. the atlas detector at the lhc accumulated integrated luminosity equal to 0.15nb@xmath0 of lead - lead data at 2.76tev per nucleon - nucleon pair. due to the excellent capabilities of the atlas detector, and its stable operation in 2010 and 2011 heavy ion physics runs,   these data allow measurements of the charged particle spectra and their ratios in different centrality bins over a wide range of transverse momenta ( 0.5150gev ) and pseudorapidity ( @xmath1 ).   the measured ratio central to peripheral events shows a suppresion by a factor of 5 at @xmath2@xmath3gev. at higher   @xmath2  the ratio increases.
in many clusters of galaxies there is evidence for cooling flows which deposit large quantities of cool gas in the central regions.   a fraction of this gas might accumulate as dense cool clouds.   the aim of this communication is to discuss the minimum temperature achievable by clouds in cooling flows of different clusters of galaxies.
for a rigid model satellite, chandrasekhar s dynamical friction formula describes the orbital evolution quite accurately, when the coulomb logarithm is chosen appropriately. however, it is not known if the orbital evolution of a real satellite with the internal degree of freedom can be described by the dynamical friction formula.   we performed @xmath0-body simulation of the orbital evolution of a self - consistent satellite galaxy within a self - consistent parent galaxy.   we found that the orbital decay of the simulated satellite is significantly faster than the estimate from the dynamical friction formula.   the main cause of this discrepancy is that the stars stripped out of the satellite are still close to the satellite, and increase the drag force on the satellite through two mechanisms.   one is the direct drag force from particles in the trailing tidal arm, a non - axisymmetric force that slows the satellite down.   the other is the indirect effect that is caused by the particles remaining close to the satellite after escape.   the force from them enhances the wake caused in the parent galaxy by dynamical friction, and this larger wake in turn slows the satellite down more than expected from the contribution of its bound mass.   we found these two have comparable effects, and the combined effect can be as large as 20% of the total drag force on the satellite.
we use the @xcite measurement of the hubble parameter at redshift @xmath0 in conjunction with 21 lower @xmath1 measurements, from @xcite, @xcite, @xcite, and @xcite, to place constraints on model parameters of constant and time - evolving dark energy cosmological models.   the inclusion of the new @xcite measurement results in @xmath2 constraints significantly more restrictive than those derived by @xcite.   these @xmath2 constraints are now more restrictive than those that follow from current type ia supernova ( snia ) apparent magnitude measurements @xcite.   the @xmath2 constraints by themselves require an accelerating cosmological expansion at about 2 @xmath3 confidence level, depending on cosmological model and hubble constant prior used in the analysis. a joint analysis of @xmath2, baryon acoustic oscillation peak length scale, and snia data favors a spatially - flat cosmological model currently dominated by a time - independent cosmological constant but does not exclude slowly - evolving dark energy density.
fractional nonlinear differential equations present an interplay between two common and important effective descriptions used to simplify high dimensional or more complicated theories : nonlinearity and fractional derivatives.   these effective descriptions thus appear commonly in physical and mathematical modeling.   we present a new series method providing systematic controlled accuracy for solutions of fractional nonlinear differential equations.   the method relies on spatially iterative use of power series expansions.   our approach permits an arbitrarily large radius of convergence and thus solves the typical divergence problem endemic to power series approaches.   we apply our method to the fractional nonlinear schrdinger equation and its imaginary time rotation, the fractional nonlinear diffusion equation. for the fractional nonlinear schrdinger equation   we find fractional generalizations of cnoidal waves of jacobi elliptic functions as well as a fractional bright soliton.   for the fractional nonlinear diffusion equation we find the combination of fractional and nonlinear effects results in a more strongly localized solution which nevertheless still exhibits power law tails, albeit at a much lower density.
we present the results of qualitative consideration of possible changes occurring during the transition from the hot accretion disc to the cool one.   we argue the possible existence of one more type of spiral density waves in the inner part of the disc where gasdynamical perturbations are negligible.   the mechanism of formation of such a wave as well as its parameters are considered.   we also present the results of 3d gasdynamical simulation of cool accretion discs.   these results confirm the hypothesis of possible formation of the spiral wave of a new,  precessional " type in the inner regions of the disc.   possible observational manifestations of this wave are discussed.
in this paper, we propose majority voting neural networks for sparse signal recovery in binary compressed sensing.   the majority voting neural network is composed of several independently trained feedforward neural networks employing the sigmoid function as an activation function.   our empirical study shows that a choice of a loss function used in training processes for the network is of prime importance.   we found a loss function suitable for sparse signal recovery, which includes a cross entropy - like term and an @xmath0 regularized term. from the experimental results  , we observed that the majority voting neural network achieves excellent recovery performance, which is approaching the optimal performance as the number of component nets grows.   the simple architecture of the majority voting neural networks would be beneficial for both software and hardware implementations.
the rate of occurrence of words is not uniform but varies from document to document. despite this observation, parameters for conventional @xmath0-gram language models   are usually derived using the assumption of a constant word rate. in this paper   we investigate the use of variable word rate assumption, modelled by a poisson distribution or a continuous mixture of poissons.   we present an approach to estimating the relative frequencies of words or @xmath0-grams taking prior information of their occurrences into account. discounting and smoothing schemes   are also considered. using the broadcast news task  , the approach demonstrates a reduction of perplexity up to 10%.   ( 0,0 ) ( 0,0 )
experiment na44 has measured proton and antiproton distributions at mid - rapidity in sulphur and proton collisions with nuclear targets at 200 and 450 gev / c per nucleon respectively.   the inverse slopes of transverse mass distributions increase with system size for both protons and antiprotons but are slightly lower for antiprotons.   this could happen if antiprotons are annihilated in the nuclear medium.   the antiproton yield increases with system size and centrality and is largest at mid - rapidity.   the proton yield also increases with system size and centrality, but decreases from backward rapidity to mid - rapidity.   the stopping of protons at these energies lies between the full stopping and nuclear transparency scenarios.   the data are in reasonable agreement with rqmd predictions except for the antiproton yields from sulphur - nucleus collisions.
the correlation dimension, that is, the dimension obtained by computing the correlation function of pairs of points of a trajectory in phase space, is a numerical technique introduced in the field of nonlinear dynamics in order to compute the dimension of the manifold in which an orbit moves, without the need of knowing the actual equations of motion that give rise to the trajectory.   this technique has been proposed in the past as a method to measure the dimension of stellar orbits in astronomical potentials, i.e., the number of isolating integrals of motion the orbits obey.   although the algorithm can in principle yield that number, some care has to be taken in order to obtain good results.   we studied the relevant parameters of the technique, found their optimal values, and tested the validity of the method on a number of potentials previously studied in the literature, using the sali, lyapunov exponents and spectral dynamics as gauges.       stellar dynamics  galaxies : kinematics and dynamics  methods : numerical
in the context of agent based modeling and network theory, we focus on the problem of recovering behavior - related choice information from origin - destination type data, a topic also known under the name of network tomography. as a basis for predicting agents choices we emphasize the connection between adaptive intelligent behavior, causal entropy maximization and self - organized behavior in an open dynamic system.   we cast this problem in the form of binary and weighted networks and suggest information theoretic entropy - driven methods to recover estimates of the unknown behavioral flow parameters.   our objective is to recover the unknown behavioral values across the ensemble analytically, without explicitly sampling the configuration space. in order to do so,   we consider the cressie - read family of entropic functionals, enlarging the set of estimators commonly employed to make optimal use of the available information. more specifically  , we explicitly work out two cases of particular interest : shannon functional and the likelihood functional.   we then employ them for the analysis of both univariate and bivariate data sets, comparing their accuracy in reproducing the observed trends.
the launch of the _ chandra _ ( nasa ) and _ xmm - newton _ ( esa ) x - ray observatories in 1999 has revolutionized our view of the universe, by providing astrophysical information about many classes of sources with unprecedent detail.   the high throughput of _ xmm - newton _ makes it the ideal instrument to provide low to moderate resolution spectroscopy of faint and extended sources. after 3 years of operations,   _ xmm - newton _ has observed all types of astronomical sources and delivered very interesting results in many areas. in this review  , we highlight a few points where the contribution of _ xmm - newton _ has significantly furthered our knowledge of the energetic universe.
we study the spectral projection associated to a barrier - top resonance for the semiclassical schrdinger operator.   first, we prove a resolvent estimate for complex energies close to such a resonance. using that estimate and an explicit representation of the resonant states,   we show that the spectral projection has a semiclassical expansion in integer powers of @xmath0, and compute its leading term.   we use this result to compute the residue of the scattering amplitude at such a resonance.   eventually, we give an expansion for large times of the schrdinger group in terms of these resonances.
we construct new black brane solutions in @xmath0 gauged @xmath1 supergravity with a general cubic prepotential, which have entropy density @xmath2 as @xmath3 and thus satisfy the nernst law. by using the real formulation of special geometry  , we are able to obtain analytical solutions in closed form as functions of two parameters, the temperature @xmath4 and the chemical potential @xmath5.   our solutions interpolate between hyperscaling violating lifshitz geometries with @xmath6 at the horizon and @xmath7 at infinity. in the zero temperature limit, where the entropy density goes to zero  , we recover the extremal nernst branes of barisch _ et al _, and the parameters of the near horizon geometry change to @xmath8.   1.5 true cm    nernst branes from special geometry + 1.0 true cm p.  dempster@xmath9, d.  errington@xmath10 and t.  mohaupt@xmath11 + @xmath10department of mathematical sciences + university of liverpool + peach street + liverpool l69 7zl, uk + p.dempster@liv.ac.uk, d.errington@liv.ac.uk, thomas.mohaupt@liv.ac.uk + @xmath12school of physics & astronomy and center for theoretical physics + seoul national university + seoul 151 - 747, korea +   january 30, 2015. revised :   february 27, 2015.   1.0 true cm
classification of high dimensional data finds wide - ranging applications. in many of these applications equipping the resulting classification with a measure of uncertainty   may be as important as the classification itself. in this paper   we introduce, develop algorithms for, and investigate the properties of, a variety of bayesian models for the task of binary classification ; via the posterior distribution on the classification labels, these methods automatically give measures of uncertainty.   the methods are all based around the graph formulation of semi - supervised learning.   we provide a unified framework which brings together a variety of methods which have been introduced in different communities within the mathematical sciences.   we study probit classification @xcite, generalize the level - set method for bayesian inverse problems @xcite to the classification setting, and generalize the ginzburg - landau optimization - based classifier @xcite to a bayesian setting ; we also show that the probit and level set approaches are natural relaxations of the harmonic function approach introduced in @xcite.   we introduce efficient numerical methods, suited to large data - sets, for both mcmc - based sampling as well as gradient - based map estimation. through numerical experiments we study classification accuracy and uncertainty quantification for our models ; these experiments showcase a suite of datasets commonly used to evaluate graph - based semi - supervised learning algorithms.   graph classification, uncertainty quantification, gaussian prior    6209, 65s05, 9404
the lick agn monitoring project 2011 observing campaign was carried out over the course of 11 weeks in spring 2011. here   we present the first results from this program, a measurement of the broad - line reverberation lag in the seyfert 1 galaxy mrk 50. combining our data with supplemental observations obtained prior to the start of the main observing campaign,   our dataset covers a total duration of 4.5 months. during this time,   mrk 50 was highly variable, exhibiting a maximum variability amplitude of a factor of @xmath0 in the @xmath1-band continuum and a factor of @xmath2 in the h@xmath3  line. using standard cross - correlation techniques  , we find that h@xmath3  and h@xmath4  lag the @xmath5-band continuum by @xmath6 and @xmath7 days, respectively, while the lag of @xmath8 is unresolved.   the h@xmath3  line exhibits a symmetric velocity - resolved reverberation signature with shorter lags in the high - velocity wings than in the line core, consistent with an origin in a broad - line region dominated by orbital motion rather than infall or outflow.   assuming a virial normalization factor of @xmath9, the virial estimate of the black hole mass is @xmath10 @xmath11.   these observations demonstrate that mrk 50 is among the most promising nearby active galaxies for detailed investigations of broad - line region structure and dynamics.
the motion of a collisionless plasma - a high - temperature, low - density, ionized gas - is described by the vlasov - maxwell ( vm ) system.   these equations are considered in one space dimension and two momentum dimensions without the assumption of relativistic velocity corrections.   the main results are bounds on the spatial and velocity supports of the particle distribution function and uniform estimates on derivatives of this function away from the critical velocity @xmath0. additionally, for initial particle distributions that are even in the second velocity argument @xmath1, the global - in - time existence of solutions is shown.   robert glassey    stephen pankavich    jack schaeffer
the aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass - selected sample of dark matter haloes.   quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. in this paper, we test the reliability of these assumptions and the quality of the analytic approximations, using ray - tracing simulations through a cosmological density field generated by very large n - body simulations.   we find that those analytic predictions which take into account the non - linear evolution of the matter distribution, such as the dispersion of the aperture mass and the halo abundance, are surprisingly accurately reproduced with our numerical results, whereas the predictions for the skewness, based on quasi - linear theory, are rather imprecise.   in particular, we verify numerically that the probability distribution of the aperture mass decreases exponentially for values much larger than the rms. given the good overall agreement,   comparisons between the observed distribution of the aperture mass and the theoretical values provide a powerful tool for testing cosmological models.   = 3.33pt plus 5.4pt minus 1.11pt
in this work, one shows that a specific non - minimal coupling between the scalar curvature and matter can mimic the dark matter component of galaxy clusters. for this purpose  , one assesses the abell cluster a586, a massive nearby relaxed cluster of galaxies in virial equilibrium, where direct mass estimates and strong - lensing determinations are possible.   one then extends the dark matter mimicking to a large sample of galaxy clusters whose density profiles are obtained from the _ chandra _ high quality data, also in virial equilibrium.   the total density, which generally follows a cusped profile and reveals a very small baryonic component, can be effectively described within this framework.
we set up the general formalism to model polytropic newtonian stars with anisotropic pressure.   we obtain the corresponding lane - emden equation. a heuristic model based on an ansatz to obtain anisotropic matter solutions from known solutions for isotropic matter   is adopted to illustrate the effects of the pressure anisotropy on the structure of the star. in particular, we calculate the chandrasekhar mass for a white dwarf. it is clearly displayed how the chandrasekhar mass limit changes depending on the anisotropy. prospective astrophysical applications of the proposed approach are discussed.
matter - quantum gravity interactions can be used for direct and also indirect experimental tests of quantum gravity.   we focus on photon - photon scattering in asymptotically safe gravity as a direct test of the small - scale structure of spacetime, and discuss how near - future experiments can probe asymptotic safety in a setting with large extra dimensions.
in the framework of an extended nambu  jona - lasinio model we are studying pion condensation in quark matter with an asymmetric isospin composition in a gravitational field of the static einstein universe at finite temperature and chemical potential.   this particular choice of the gravitational field configuration enables us to investigate phase transitions of the system with exact consideration of the role of this field in the formation of quark and pion condensates and to point out its influence on the phase portraits.   we demonstrate the effect of oscillations of the thermodynamic quantities as functions of the curvature and also refer to a certain similarity between the behavior of these quantities as functions of curvature and finite temperature.   finally, the role of quantum fluctuations for spontaneous symmetry breaking in the case of a finite volume of the universe is shortly discussed.
we study the gravitational scattering of massive particles with and without spin in the effective theory of gravity at one loop level.   our focus is on long distance effects arising from nonanalytic components of the scattering amplitude and we show that the spin - independent and the spin - dependent long range components exhibit a universal form.   both classical and quantum corrections are obtained, and the definition of a proper second order potential is discussed.
we discuss a few examples of structure functions for polarized, semi - inclusive scattering processes to show the richness of structure.   then we indicate how polarization and particle production can be used to study the quark and gluon structure of hadrons going further than the well - known parton densities and fragmentation functions.   we also emphasize how single spin asymmetries in leptoproduction may shed light on explanations for single spin asymmetries in pion production in pp collissions.   -0.8 cm -0.8 cm = 16.8 cm by -2.4 cm    vuth 99 - 06    1 cm    * beyond collinearity in the n(e,   eq ) process *    0.5 cm    p.j.   mulders    0.3 cm    _ department of physics and astronomy, faculty of sciences, vrije universiteit _   _ de boelelaan 1081, 1081 hv amsterdam, the netherlands _    1 cm
displacements of atoms and molecules away from lattice sites in helium and parahydrogen solids at low temperature have been studied by means of quantum monte carlo simulations. in the bcc phases of @xmath0he and @xmath1he, atomic displacements are largely quantum - mechanical in character, even at melting. the computed lindemann ratio at melting is found to be in good agreement with experimental results for @xmath1he. unlike the case of helium, in solid parahydrogen there exists near melting a significant thermal contribution to molecular vibrations, accounting for roughly half of the total effect.   although the lindemann ratio at melting is in quantitative agreement with experiment, computed molecular mean square fluctuations feature a clear temperature dependence, in disagreement with recent experimental observations.
we present the findings of our weak lensing study of a sample of 116 cnoc2 galaxy groups.   the lensing signal is used to estimate the mass - to - light ratio of these galaxy groups. the best fit isothermal sphere model to our lensing data has an einstein radius of 088@xmath0012, which corresponds to a shear - weighted velocity dispersion of 245@xmath018 km s@xmath1.   the mean mass - to - light ratio within 1 h@xmath1 mpc is 185@xmath028 hm@xmath2/l@xmath3 and is independent of radius from the group center.   the signal - to - noise ratio of the shear measurement is sufficient to split the sample into subsets of `` poor '' and `` rich '' galaxy groups.   the poor galaxy groups were found to have an average velocity dispersion of 193@xmath4 km s@xmath1 and a mass - to - light ratio of 134@xmath026 hm@xmath5/l@xmath3, while the rich galaxy groups have a velocity dispersion of 270@xmath6 km s@xmath1 and a mass - to - light ratio of 278@xmath042 hm@xmath5/l@xmath3, similar to the mass - to - light ratio of clusters. this steep increase in the mass - to - light ratio as a function of mass, suggests that the mass scale of @xmath7m@xmath5 is where the transition between the actively star - forming field environment and the passively - evolving cluster environment occurs.   this is the first such detection from weak lensing.
we demonstrate that the entropy of entanglement and the distillable entanglement of regions with respect to the rest of a general harmonic lattice system in the ground or a thermal state scale at most as the boundary area of the region. this area law is rigorously proven to hold true in non - critical harmonic lattice system of arbitrary spatial dimension, for general finite - ranged harmonic interactions, regions of arbitrary shape and states of nonzero temperature. for nearest - neighbor interactions   corresponding to the klein - gordon case  upper and lower bounds to the degree of entanglement can be stated explicitly for arbitrarily shaped regions, generalizing the findings of [ phys.   rev.   lett.  * 94 *, 060503 ( 2005 ) ].   these higher dimensional analogues of the analysis of block entropies in the one - dimensional case show that under general conditions, one can expect an area law for the entanglement in non - critical harmonic many - body systems.   the proofs make use of methods from entanglement theory, as well as of results on matrix functions of block banded matrices.   disordered systems are also considered.   we moreover construct a class of examples for which the two - point correlation length diverges, yet still an area law can be proven to hold.   we finally consider the scaling of classical correlations in a classical harmonic system and relate it to a quantum lattice system with a modified interaction.   we briefly comment on a general relationship between criticality and area laws for the entropy of entanglement.
this paper presents a quantification of the x - ray variability amplitude for 79  observations of 36 seyfert 1 galaxies.   we find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into the established correlation between x - ray variability and nuclear luminosity.   consideration of the x - ray spectral index and variability properties together shows distinct groupings in parameter space for broad and narrow - line seyfert 1 galaxies, confirming previous studies.   a strong correlation is found between hard x - ray variability and fwhm h@xmath0.   a range of nuclear mass and accretion rate across the seyfert population can explain the differences observed in x - ray and optical properties.   an attractive alternative model, which does not depend on any systematic difference in central mass, is that the circumnuclear gas of nlsy1s is different to blsy1s in temperature, optical depth, density or geometry.   = = = 1=1=0pt = 2=2=0pt = 2=2=0pt
we present the follow - up of three medium redshift galaxy clusters from the sharc survey observed with xmm  newton.   we studied rx  j0256.5 + 0006 which shows two components which are very likely in interaction.   the smallest component exhibits a comet - like structure indicating ram pressure stripping as it falls onto the main cluster. the second cluster, rx  j2237.0 - 1516 is an elliptical cluster with a gas temperature of 3.0@xmath00.5kev. the third cluster, rx  j1200.8 - 0328 seems to be in a relaxed state because its shape is regular and we do not see obvious temperature gradient.   its mean temperature is 5.1@xmath1kev.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
low temperature quantum corrections to the density of states ( dos ) and the conductivity are examined for a two  dimensional(2d ) square crystal with substitutional impurities. by summing the leading logarithmic corrections to the dos its energy dependence near half   filling is obtained.   it is shown that substitutional impurities do not suppress the van hove singularity at the middle of the band, however they change its energy dependence strongly.   weak disorder due to substitutional impurities in the three  dimensional simple cubic lattice results in a shallow dip in the center of the band.   the calculation of quantum corrections to the conductivity of a 2d lattice shows that the well  known logarithmic localization correction exists for all band fillings.   furthermore the magnitude of the correction increases as half  filling is approached.   the evaluation of the obtained analytical results shows evidence for delocalized states in the center of the band of a 2d lattice with substitutional impurities.
the cross - kerr effect is studied for two weak beams, probe and trigger, propagating in an atomic medium in a tripod configuration, dressed by a strong standing wave coupling beam in a regime of electromagnetically induced transparency.   the nonlinear phase shifts for both transmitted and reflected probe beams induced by the trigger s presence are found to depend on the probe detuning, the control beams intensity, the relaxation rates and, in particular, on the redistribution of the population among the atomic levels.   such a quantitative analysis indicates that the transmitted and reflected probe beam components and their respective phase shifts can be easily controlled and optimized.
we show that the fermion determinant for 2-d wilson lattice fermions coupled to an external scalar field is equivalent to self avoiding loops interacting with the external field. in an application of the resulting formula   we integrate the scalar field with a gaussian action to generate the @xmath0-component gross - neveu model.   the loop representation for this model is discussed.   mit - ctp-2800 + hep - lat/9811014    * christof gattringer *    massachusetts institute of technology + center for theoretical physics + 77 massachusetts avenue + cambridge ma 02129, usa    pacs : 11.15.ha + key words : lattice field theory, fermion determinant
in this paper we construct the complete evolution of the universe driven by the mass dimension one dark spinor called elko, starting from the inflation, passing by the matter dominated era and finishing with the recent accelerated expansion.   the dynamic of the elko spinor field with a symmetry breaking type potential can reproduce all the phases of the universe in a natural and elegant way.   the dynamic equations in general case and slow roll conditions in the limit @xmath0 are also presented for the elko system.
we consider the quantum vacuum of fermionic field in the presence of a black - hole background as a possible candidate for the stabilized black hole. the stable vacuum state ( as well as thermal equilibrium states with arbitrary temperature ) can exist if we use the painlev - gullstrand description of the black hole, and the superluminal dispersion of the particle spectrum at high energy, which is introduced in the free - falling frame.   such choice is inspired by the analogy between the quantum vacuum and the ground state of quantum liquid, in which the event horizon for the low - energy fermionic quasiparticles also can arise.   the quantum vacuum is characterized by the fermi surface, which appears behind the event horizon.   we do not consider the back reaction, and thus there is no guarantee that the stable black hole exists.   but if it does exist, the fermi surface behind the horizon would be the necessary attribute of its vacuum state.   we also consider exact discrete spectrum of fermions inside the horizon which allows us to discuss the problem of fermion zero modes.
collisionless n - body simulations of merging disk - galaxies with mass ratios ( @xmath0 ) of 1:1, 2:1, 3:1, and 4:1 have been performed using direct summation with the special purpose hardware grape.   the simulations are used to examine whether the formation of elliptical galaxies can be explained in the context of the merger scenario.   the photometric, kinematical and isophotal properties of the merger remnants are investigated and turn out to be in very good agreement with observations of giant elliptical galaxies. we conclude that equal mass mergers lead to slowly rotating, anisotropic remnants having predominantly boxy isophotes.   mergers with a mass ratio of 3:1 and 4:1, on the other hand, are fast isotropic rotators with disky isophotes.   projection effects can explain the observed scatter in the kinematical and isophotal properties of elliptical galaxies.
we report the results of _ chandra _  and _ xmm - newton _  observations of a new outburst of an ultraluminous supersoft x - ray source in m101.   cxouj140332.3 + 542103  was observed in a low luminosity state ( @xmath0 ) between 2004 january and may.   the low - state x - ray spectra were relatively hard ; the combined low state spectrum can be fitted with a combination of a power - law with photon index of 1.4 and a blackbody of 63 ev. during 2004   july, the source underwent a strong outburst and the peak 0.37 kev luminosity reached @xmath1, with a bolometric luminosity of about @xmath2.   the outburst spectra were very soft and can generally be fitted with a blackbody model with temperatures of 50100 ev. in two of the observations, absorption edges at 0.33 kev, 0.56 kev, 0.66 kev, and 0.88 kev were found.   an _   xmm - newton _  observation was also performed during the decay of the outburst, and a power - law tail was seen in addition to the supersoft spectrum.   we consider different accretion models ; one involving an intermediate - mass black hole can explain the observations.   # 1to 0pt#1
we propose a scheme for generating atomic noon states via adiabatic passage. in the scheme,   a double @xmath0-type three - level atom is trapped in a bimodal cavity and two sets of @xmath0-type three - level atoms are translated into and outside of two single mode cavities respectively.   the three cavities connected by optical fibres are always in vacuum states. after a series of operations and suitable interaction time  , we can obtain arbitrary large-@xmath1 noon states of two sets of @xmath0-type three - level atoms in distant cavities by performing a single projective measurement on the double @xmath0-type three - level atom.   due to adiabatic elimination of atomic excited states and the application of adiabatic passage, our scheme is robust against the spontaneous emissions of atoms, the decays of fibres and cavities photon leakage.   so the scheme has a high fidelity and feasibility under the current available techniques.   + * keywords : * noon states @xmath2 adiabatic passage @xmath2 cavity quantum electrodynamics    gbksong
we study the evolution of nitrogen resulting from a set of spiral and irregular galaxy models computed for a large number of input mass radial distributions and with various star formation efficiencies.   we show that our models produce a nitrogen abundance evolution in good agreement with the observational data. in particular, low n / o values for high - redshift objects, such as those obtained for damped lyman alpha galaxies   can be obtained with our models simultaneously to higher and constant values of n / o as those observed for irregular and dwarf galaxies, at the same low oxygen abundances @xmath0 dex.   the differences in the star formation histories of the regions and galaxies modeled are essential to reproduce the observational data in the n / o - o / h plane.   
we report the recovery of a spectroscopic event in @xmath0 carinae in 1997/98 after a prediction by damineli ( 1996 ). a true periodicity with @xmath1 days ( 0.2% uncertainty ) is obtained.   the line intensities and the radial - velocity curve display a phase - locked behavior implying that the energy and dynamics of the event repeat from cycle to cycle.   this rules out s doradus oscillation or multiple shell ejection by an unstable star as the explanation of the spectroscopic events.   a colliding - wind binary scenario is supported by our spectroscopic data and by x - ray observations.   although deviations from a simple case exist around periastron, intensive monitoring during the next event ( mid 2003 ) will be crucial to the understanding of the system.
the onset of spiral structure in galaxies appears to occur between redshifts 1.4 and 1.8 when disks have developed a cool stellar component, rotation dominates over turbulent motions in the gas, and massive clumps become less frequent. during the transition from clumpy to spiral disks,   two unusual types of spirals are found in the hubble ultra deep field that are massive, clumpy and irregular like their predecessor clumpy disks, yet spiral - like or sheared like their descendants.   one type is `` woolly '' with massive clumpy arms all over the disk and is brighter than other disk galaxies at the same redshift, while another type has irregular multiple arms with high pitch angles, star formation knots and no inner symmetry like today s multiple - arm galaxies.   the common types of spirals seen locally are also present in a redshift range around @xmath0, namely grand design with two symmetric arms, multiple arm with symmetry in the inner parts and several long, thin arms in the outer parts, and flocculent, with short, irregular and patchy arms that are mostly from star formation.   normal multiple arm galaxies are found only closer than @xmath1 in the udf.   grand design galaxies extend furthest to @xmath2, presumably because interactions can drive a two - arm spiral in a disk that would otherwise have a more irregular structure.   the difference between these types is understandable in terms of the usual stability parameters for gas and stars, and the ratio of the velocity dispersion to rotation speed.
eukaryotic adaptation pathways operate within wide - ranging environmental conditions without stimulus saturation. despite numerous differences in the adaptation mechanisms employed by bacteria and eukaryotes,   all require energy consumption. here  , we present two minimal models showing that expenditure of energy by the cell is not essential for adaptation.   both models share important features with large eukaryotic cells : they employ small diffusible molecules and involve receptor subunits resembling highly conserved g - protein cascades.   analyzing the drawbacks of these models helps us understand the benefits of energy consumption, in terms of adjustability of response and adaptation times as well as separation of cell - external sensing and cell - internal signaling.   our work thus sheds new light on the evolution of adaptation mechanisms in complex systems.
conversion of microwave radiation into the optical range has been predicted to reach unity quantum efficiency in whispering gallery resonators made from an optically nonlinear crystal and supporting microwave and optical modes simultaneously. in this work   we theoretically explore and experimentally demonstrate a resonator geometry that can provide the required phase matching for such a conversion at any desired frequency in the sub - thz range.   we show that such a ring - shaped resonator not only allows for the phase matching, but also maximizes the overlap of the interacting fields. as a result  , unity - efficient conversion is expected in a resonator with feasible parameters.
tadpole galaxies look like a star forming head with a tail structure to the side. they are also named cometaries. in a series of recent works   we have discovered a number of issues that lead us to consider them extremely interesting targets.   first, from images, they are disks with a lopsided starburst.   this result is firmly established with long slit spectroscopy in a nearby representative sample.   they rotate with the head following the rotation pattern but displaced from the rotation center. moreover, in a search for extremely metal poor ( xmp ) galaxies, we identified tadpoles as the dominant shapes in the sample   nearly 80% of the local xmp galaxies have a tadpole morphology.   in addition, the spatially resolved analysis of the metallicity shows the remarkable result that there is a metallicity drop right at the position of the head.   this is contrary to what intuition would say and difficult to explain if star formation has happened from gas processed in the disk.   the result could however be understood if the star formation is driven by pristine gas falling into the galaxy disk.   if confirmed, we could be unveiling, for the first time, cool flows in action in our nearby world.   the tadpole class is relatively frequent at high redshift   10% of resolvable galaxies in the hubble udf   but less than 1% in the local universe.   they are systems that could track cool flows and test models of galaxy formation.    2
a family of maps or flows depending on a parameter @xmath0 which varies in an interval, spans a certain property if along the interval this property depends continuously on the parameter and achieves some asymptotic values along it.   we consider families of periodically forced hamiltonian systems for which the appropriately scaled frequency @xmath1 is spanned, namely it covers the semi - infinite line @xmath2 under some natural assumptions on the family of flows and its adiabatic limit, we construct a convenient labelling scheme for the primary homoclinic orbits which may undergo a countable number of bifurcations along this interval. using this scheme   we prove that a properly defined flux function is @xmath3 in @xmath4 combining this proof with previous results of rk and poje, immediately establishes that the flux function and the size of the chaotic zone depend on the frequency in a non - monotone fashion for a large class of families of hamiltonian flows.
while the expansion rate of a homogeneous isotropic universe is simply proportional to the square - root of the energy density, the expansion rate of an inhomogeneous universe also depends on the nature of the density inhomogeneities. in this paper   we calculate to second order in perturbation variables the expansion rate of an inhomogeneous universe and demonstrate corrections to the evolution of the expansion rate.   while we find that the mean correction is small, the variance of the correction on the scale of the hubble radius is sensitive to the physical significance of the unknown spectrum of density perturbations beyond the hubble radius.
we report on the modeling, simulation and experimental demonstration of complete mode crossings of fano resonances within chip - integrated microresonators.   the continuous reshaping of resonant lineshapes is achieved via nonlinear thermo - optical tuning when the cavity - coupled optical pump is partially absorbed by the material.   the locally generated heat then produces a thermal field, which influences the spatially overlapping optical modes, allowing thus to alter the relative spectral separation of resonances.   furthermore, we exploit such tunability to probe continuously the coupling between different families of quasi - degenerate modes that exhibit asymmetric fano - interactions. as a particular case,   we demonstrate for the first time a complete disappearance of one of the modal features in the transmission spectrum as predicted by u. fano [ phys.   rev.   124, 1866 ( 1961 ) ].   the phenomenon is modeled as a third order non - linearity with a spatial distribution that depends on the stored optical field and the thermal diffusion within the resonator.   the performed non - linear numerical simulations are in excellent agreement with the experimental results, which confirm the validity of the developed theory.
unexpected increases in demand and most of all flash crowds are considered the bane of every web application as they may cause intolerable delays or even service unavailability.   proper quality of service policies must guarantee rapid reactivity and responsiveness even in such critical situations.   previous solutions fail to meet common performance requirements when the system has to face sudden and unpredictable surges of traffic.   indeed they often rely on a proper setting of key parameters which requires laborious manual tuning, preventing a fast adaptation of the control policies.   we contribute an original self- * overload control ( soc ) policy.   this allows the system to self - configure a dynamic constraint on the rate of admitted sessions in order to respect service level agreements and maximize the resource utilization at the same time.   our policy does not require any prior information on the incoming traffic or manual configuration of key parameters.   we ran extensive simulations under a wide range of operating conditions, showing that socrapidly adapts to time varying traffic and self - optimizes the resource utilization.   it admits as many new sessions as possible in observance of the agreements, even under intense workload variations.   we compared our algorithm to previously proposed approaches highlighting a more stable behavior and a better performance.
we report the discovery of the likely orbital period of the ultracompact low - mass x - ray binary ( lmxb ) 2s  0918@xmath0549. using time - resolved optical photometry carried out with the 8-m gemini south telescope  , we obtained a 2.4-hr long, sloan @xmath1 light curve of 2s  0918@xmath0549  and found a periodic, sinusoidal modulation at 17.4@xmath2 min with a semiamplitude of 0.015@xmath3 mag, which we identify as the binary period.   in addition to 4u 0513@xmath040 in the globular cluster ngc  1851 and the galactic disk source 4u 1543@xmath0624, 2s  0918@xmath0549  is the third member of the ultracompact lmxbs that have orbital periods around 18 min.   our result verifies the suggestion of 2s  0918@xmath0549  as an ultracompact binary based on its x - ray and optical spectroscopic properties. given that the donor in 2s  0918@xmath0549  has been suggested to be either a c - o or he white dwarf, its likely mass and radius are around 0.0240.029 @xmath4 and 0.030.032 @xmath5, respectively, for the former case and 0.0340.039 @xmath4 and 0.0330.035 @xmath5 for the latter case.   if the optical modulation arises from x - ray heating of the mass donor, its sinusoidal shape suggests that the binary has a low inclination angle, probably around 10.
both pulsation and mass loss are commonly observed in stars and are important ingredients for understanding stellar evolution and structure, especially for massive stars.   there is a growing body of evidence that pulsation can also drive and enhance mass loss in massive stars and that pulsation - driven mass loss is important for stellar evolution. in this review  , i will discuss recent advances in understanding pulsation driven mass loss in massive main sequence stars, classical cepheids and red supergiants and present some challenges remaining.
we present a list of candidates for high redshift late  type galaxies in the field around the @xmath0 quasar pc1643 + 4631a.   deep @xmath1,@xmath2 and @xmath3 imaging has been used to search for objects with a strong lyman break between @xmath1 and @xmath2, characteristic of galaxies with high hydrogen column densities at @xmath4.   a further study of the red objects detected by hu & ridgway ( @xcite ) has been done, allowing the temptative identification of many of them as low redshift ( @xmath5 ) elliptical galaxies.
the free parameters of a flat accelerating model without dark energy are constrained by using supernovae type ia and observational h(z ) data. instead of the vacuum dominance,   the present accelerating stage in this modified einstein - de sitter cosmology is a consequence of the gravitationally - induced particle production of cold dark matter.   the model present a transition from a decelerating to an accelerating regime at low redshifts, and is also able to harmonize a cold dark matter picture with the latest measurements of the hubble constant @xmath0, the supernovae observations ( constitution sample ), and the h(z ) data.
a frequentist asymptotic expansion method for error estimation is employed for a network of gravitational wave detectors to assess the amount of information that can be extracted from gravitational wave observations.   mathematically we derive lower bounds in the errors that any parameter estimator will have in the absence of prior knowledge to distinguish between the post - einsteinian ( ppe ) description of coalescing binary systems and that of general relativity.   when such errors are smaller than the parameter value, there is possibility to detect these violations from gr.   a parameter space with inclusion of dominant dephasing ppe parameters @xmath0 is used for a study of first- and second - order ( co)variance expansions, focusing on the inspiral stage of a nonspinning binary system of zero eccentricity detectible through adv.ligo and adv.virgo.   our procedure is an improvement of the cramr - rao lower bound.   when bayesian errors are lower than our bound it means that they depend critically on the priors.   the analysis indicates the possibility of constraining deviations from gr in inspiral snr ( @xmath1 ) regimes that are achievable in upcoming scientific runs ( gw150914 had an inspiral snr @xmath2 ). the errors on @xmath3 also increase errors of other parameters such as the chirp mass @xmath4 and symmetric mass ratio @xmath5.   application is done to existing alternative theories of gravity, which include modified dispersion relation of the waveform, non - spinning models of quadratic modified gravity, and dipole gravitational radiation ( i.e., brans - dicke type ) modifications.
to clarify the origin of a charge - density wave ( cdw ) phase in 1@xmath0-tise@xmath1, we study the ground state property of a half - filled two - band hubbard model in a triangular lattice including electron - phonon interaction. by using the variational monte carlo method,   the electronic and lattice degrees of freedom are both treated quantum mechanically on an equal footing beyond the mean - field approximation.   we find that the cooperation between coulomb interaction and electron - phonon interaction is essential to induce the cdw phase.   we show that the `` pure '' exciton condensation without lattice distortion is difficult to realize under the poor nesting condition of the underlying fermi surface.   furthermore, by systematically calculating the momentum resolved hybridization between the two bands, we examine the character of electron - hole pairing from the viewpoint of bcs - bec crossover within the cdw phase and find that the strong - coupling bec - like pairing dominates.   we therefore propose that the cdw phase observed in 1@xmath0-tise@xmath1 originates from a bec - like electron - hole pairing.
we explore a technique for identifying the highest redshift ( @xmath0 ) sources in _ herschel_/spire and blast submillimeter surveys by localizing the position of the far - infrared dust peak. just as _   spitzer_/irac was used to identify stellar ` bump'sources, the far - ir peak is also a redshift indicator ; although, the latter also depends on the average dust temperature.   we demonstrate the wide range of allowable redshifts for a reasonable range of dust temperatures and show that it is impossible to constraint the redshift of individual objects using solely the position of the far - ir peak. by fitting spectral energy distribution models to simulated _ herschel_/spire photometry we show the utility of radio and/or far - infrared data in breaking this degeneracy. with prior knowledge of the dust temperature distribution   it is possible to obtain statistical samples of high redshift submillimeter galaxy candidates.   we apply this technique to the blast survey of ecdfs to constrain the number of dusty galaxies at @xmath0.   we find @xmath1 galaxies with flux density ratios of @xmath2 ; this sets an upper limit of @xmath3deg@xmath4 if we assume all are at @xmath0.   this is @xmath5% of all 500@xmath6m - selected galaxies down to s@xmath7mjy ( @xmath8 for @xmath0 ).   modeling with conventional temperature and redshift distributions estimates the percentage of these 500@xmath6 m peak galaxies at @xmath0 to be between 1085%.   our results are consistent with other estimates of the number density of very high redshift submillimeter galaxies and follows the decline in the star formation rate density at @xmath0.
we introduce a model of a dual - core optical waveguide with opposite signs of the group - velocity - dispersion ( gvd ) in the two cores, and a phase - velocity mismatch between them. the coupler is embedded into an active host medium, which provides for the linear coupling of a gain - loss type between the two cores.   the same system can be derived, without phenomenological assumptions, by considering the three - wave propagation in a medium with the quadratic nonlinearity, provided that the depletion of the second - harmonic pump is negligible.   this linear system offers an optical realization of the charge - parity ( @xmath0 ) symmetry, while the addition of the intra - core cubic nonlinearity breaks the symmetry. by means of direct simulations and analytical approximations  , it is demonstrated that the linear system generates expanding gaussian states, while the nonlinear one gives rise to broad oscillating solitons, as well as a general family of stable stationary gap solitons.
we summarize the recent theoretical and numerical works on spin turbulence ( st ) in spin-1 spinor bose - einstein condensates.   when the system is excited from the ground state, it goes through hydrodynamic instability to st in which the spin density vector has various disordered direction.   the properties of st depend on whether the spin - dependent interaction is ferromagnetic or antiferromagnetic.   st has some characteristics different from other kinds of turbulence in quantum fluids.   firstly, the spectrum of the spin - dependent interaction energy exhibits the characteristic power law different from the usual kolmogorov -5/3 law.   secondly, st can show the spin - glass - like behavior ; the spin density vectors are spatially random but temporally frozen.
optical and near - infrared observations of the grb990705 error box were carried out with eso telescopes at la silla and paranal in chile and with the noao spirex 0.6-meter telescope in antarctica.   we detected the counterpart of this grb in the near - infrared @xmath0 band and optical @xmath1 band.   the power - law decline of the near - infrared lightcurve is rather steep with a decay index @xmath2 @xmath3 1.7 in the first hours, and a possible steepening after one day.   broadband spectral analysis of the optical / near - infrared afterglow suggests that this grb took place in a high density environment. a deep optical image obtained at antu ( vlt - ut1 ) about 5 days after the grb trigger shows at the position of the transient an extended object which might be the host galaxy of grb990705.
we examine how the current  voltage characteristics of a doped weakly coupled superlattice depends on temperature.   the drift velocity of a discrete drift model of sequential tunneling in a doped gaas / alas superlattice is calculated as a function of temperature.   numerical simulations and theoretical arguments show that increasing temperature favors the appearance of current self - oscillations at the expense of static electric field domain formation.   our findings agree with available experimental evidence.    2
dirac ( distributed infrastructure with remote agent control ) is a general framework for the management of tasks over distributed heterogeneous computing environments.   it has been originally developed to support the production activities of the lhcb ( large hadron collider beauty ) experiment and today is extensively used by several particle physics and biology communities.   current ( _ fermi_large area telescope  lat ) and planned ( cherenkov telescope array   cta ) new generation astrophysical / cosmological experiments, with very large processing and storage needs, are currently investigating the usability of dirac in this context.   each of these use cases has some peculiarities : _   fermi_-lat will interface dirac to its own workflow system to allow the access to the grid resources, while cta is using dirac as workflow management system for monte carlo production and analysis on the grid.   we describe the prototype effort that we lead toward deploying a dirac solution for some aspects of _ fermi_-lat and cta needs.
a population of x - ray dominated gamma - ray bursts ( grbs ) observed by _ ginga _, _ bepposax _  and _ hete-2_should be represented in the batse  data as presumably soft bursts.   we have performed a search for soft grbs in the batse  records in the 25100 kev energy band.   a softness of a burst spectrum can be a reason why it has been missed by the on - board procedure and previous searches for untriggered grbs tuned to 50300 kev range.   we have found a surprisingly small number ( @xmath0 yr@xmath1 down to 0.1 ph @xmath2 s@xmath1 ) of soft grbs where the count rate is dominated by 2550 kev energy channel.   this fact as well as the analysis of _ hete-2 _  and common _   bepposax_/batse  grbs indicates that the majority of grbs with a low @xmath3 has a relatively hard tail with the high - energy power - law photon index @xmath4.   an exponential cutoff in grb spectra below 20 kev may be a distinguishing feature separating non - grb events.       gamma - ray bursts  methods : data analysis
the drift velocity in drift tubes of the cms muon chambers is a key parameter for the muon track reconstruction and trigger.   it needs to be monitored precisely in order to detect any deviation from its nominal value.   a change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity.   furthermore, the temperature and magnetic field influence its value.   first data, taken with a dedicated velocity drift chamber ( vdc ) built by rwth aachen iiia are presented.   another important parameter to be monitored is the pressure inside the muon drift tube chambers.   the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak.   latest drift velocity monitoring results are discussed.
a macronova ( kilonova ) was discovered with a short gamma - ray burst, grb 130603b, which is widely believed to be powered by the radioactivity of @xmath0-process elements synthesized in the ejecta of a neutron star binary merger. as an alternative  , we propose that macronovae are energized by the central engine, i.e., a black hole or neutron star, and the injected energy is emitted after the adiabatic expansion of ejecta.   this engine model is motivated by extended emission of short grbs. in order to compare the theoretical models with observations, we develop analytical formulae for the light curves of macronovae.   the engine model allows a wider parameter range, especially smaller ejecta mass, and better fit to observations than the @xmath0-process model.   future observations of electromagnetic counterparts of gravitational waves should distinguish energy sources and constrain the activity of central engine and the @xmath0-process nucleosynthesis.
accretion - powered x - ray pulsars are among the most luminous x - ray sources in the galaxy. however, despite decades of theoretical and observational work since their discovery, no satisfactory model for the formation of the observed x - ray spectra has emerged. in particular, the previously available theories are unable to reproduce the power - law variation observed at high energies in many sources. in this paper, we present the first self - consistent calculation of the spectrum emerging from a pulsar accretion column that includes an explicit treatment of the energization occurring in the shock. using a rigorous eigenfunction expansion method based on the exact dynamical solution for the velocity profile in the column, we obtain a closed - form expression for the green s function describing the upscattering of radiation injected into the column from a monochromatic source located at the top of the thermal mound, near the base of the flow.   the green s function is convolved with a planck distribution to calculate the radiation spectrum resulting from the reprocessing of blackbody photons emitted by the thermal mound.   we demonstrate that the energization of the photons in the shock naturally produces an x - ray spectrum with a power - law shape at high energies and a blackbody shape at low energies, in agreement with many observations of accreting x - ray pulsars.
we show how to switch on and off the ratchet potential of a collective brownian motor, depending only on the position of the particles, in order to attain a current higher than or at least equal to that induced by any periodic flashing.   maximization of instant velocity turns out to be the optimal protocol for one particle but is nevertheless defeated by a periodic switching when a sufficiently large ensemble of particles is considered.   the protocol presented in this letter, although not the optimal one, yields approximately the same current as the optimal protocol for one particle and as the optimal periodic switching for an infinite number of them.
ultraluminous x - ray sources ( ulxs ) with x - ray luminosities larger than the eddington luminosity of stellar mass objects may be powered by intermediate mass black holes ( ibhs ) of masses @xmath0.   if ibhs form in young dense stellar clusters, they can be fed by roche lobe overflow from a tidally captured massive ( @xmath1 ) stellar companion. after the donor leaves the main sequence it forms a compact remnant, which spirals in due to gravitational wave ( gw ) emission.   we show that space based detectors such as the _ laser interferometer space antenna _ are likely to detect several of these sources.   gw sources stemming from this scenario have small eccentricities which give distinct gw signals.   detection of such a gw signal will unambiguously prove the existence of ibhs, and support the hypothesis that some ulxs are powered by ibhs with captured companions.       gravitational waves - black hole physics - stellar dynamics - galaxies : star clusters - x - rays : binaries
we investigate the capabilities of a quantum computer based on cold trapped ions in presence of non - dissipative decoherence.   the latter is accounted by using the evolution time as a random variable and then averaging on a properly defined probability distribution.   severe bounds on computational performances are found.
we use information entropy to test the isotropy in the nearby galaxy distribution mapped by the two micron all - sky redshift survey ( 2mrs ). we find that the galaxy distribution is highly anisotropic on small scales.   the radial anisotropy gradually decreases with increasing length scales and the observed anisotropy is consistent with that expected for an isotropic poisson distribution beyond a length scale of @xmath0. using mock catalogues from n - body simulations, we find that the galaxy distribution in the 2mrs exhibits a degree of anisotropy compatible with that of the @xmath1cdm model after accounting for the clustering bias of the 2mrs galaxies.   we also quantify the polar and azimuthal anisotropies and identify two directions @xmath2, @xmath3 which are significantly anisotropic compared to the other directions in the sky.   we suggest that their preferential orientations on the sky may indicate a possible alignment of the local group with two nearby large scale structures. despite the differences in the degree of anisotropy on small scales, we find that the galaxy distributions in both the 2mrs and the @xmath1cdm model are isotropic on a scale of @xmath0.       methods : numerical - galaxies : statistics - cosmology : theory - large scale structure of the universe.
of the known pulsar wind nebulae, 8 are good candidates for being in the early stage of evolution where the wind nebula is interacting with the freely expanding supernova ejecta.   several of these have been identified with historical supernovae.   although the identification of sn 1181 with 3c 58 has been thought to be relatively secure, the large size of the nebula, the amount of swept up mass, and the internal energy indicate a larger age. for g11.20.3,   the nebular size and internal energy are consistent with the identification with the possible supernova of 386.   although the crab nebula appears to have approximate energy equipartition between particles and the magnetic field, the nebulae 3c 58 and msh 1552 appear to be particle dominated.   the low magnetic field is consistent with models in which the nebulae are created by a shocked pulsar wind.   # 1to 40truept*#1 *
we consider new - physics ( np ) contributions to the decay @xmath0.   we parameterize the np couplings by an effective lagrangian consisting of 10 lorentz structures.   we show that the presence of np can be detected through the measurement of the partial width.   a partial identification of the np can be achieved through the measurements of a forward - backward - like asymmetry, a top - quark - spin - dependent asymmetry, the partial rate asymmetry, and a triple - product asymmetry.   these observables, which vanish in the standard model, can all take values in the 10 - 20% range in the presence of np. since @xmath1,   most of our results also hold, with small changes, for @xmath2.
the anisotropic kondo necklace model in 2d and 3d is treated as a genuine model for magnetic to kondo singlet quantum phase transitions in the heavy fermion ( hf ) compounds.   the variation of the quantum critical point ( qcp ) with anisotropy parameters has been investigated previously in the zero field case @xcite. here   we extend the treatment to finite fields using a generalised bond operator representation including all triplet states.   the variation of critical t@xmath0 with magnetic field and the associated phase diagram is derived.   the influence of anisotropies and the different g - factors for localised and itinerant spins on the field dependence of t@xmath0 is also investigated.   it is found that three different types of behaviour may appear : ( i ) destruction of antiferromangetism and appearance of a singlet state above a critical field.   ( ii ) the inverse behaviour, namely field induced antiferromagnetism out of the kondo singlet phase. (   iii ) reentrance behaviour of the kondo singlet phase as function of field strength.
i consider the generic situation where a finite number of identical test systems in varying ( possibly unknown ) initial states are subjected independently to the same unknown process.   i show how one can infer from the output data alone whether or not the process in question induces thermalization, and if so, which constants of the motion characterize the final equilibrium states. in case thermalization   does occur and there is no evidence for constants of the motion other than energy, i further show how the same output data can be used to estimate the test systems effective hamiltonian. for both inference tasks   i devise a statistical framework inspired by the generic techniques of factor and principal component analysis.   i illustrate its use in the simple example of qubits.
we define the _ violation fraction _ @xmath0 as the cumulative fraction of time that the entropy change is negative during single realizations of processes in phase space.   this quantity depends both on the number of degrees of freedom @xmath1 and the duration of the time interval @xmath2. in the large-@xmath2 and large-@xmath1   limit we show that, for ergodic and microreversible systems, the mean value of @xmath0 scales as @xmath3.   the exponent @xmath4 is positive and generally depends on the protocol for the external driving forces, being @xmath5 for a constant drive. as an example, we study a nontrivial model where the fluctuations of the entropy production are non - gaussian : an elastic line driven at a constant rate by an anharmonic trap. in this case we show that the scaling of @xmath6 with @xmath1 and @xmath2 agrees with our result.   finally, we discuss how this scaling law may break down in the vicinity of a continuous phase transition.
we present a simple mathematical framework for the description of the dynamics of glassy systems in terms of a random walk in a complex energy landscape pictured as a network of minima.   we show how to use the tools developed for the study of dynamical processes on complex networks, in order to go beyond mean - field models that consider that all minima are connected to each other.   we consider several possibilities for the transition rates between minima, and show that in all cases the existence of a glassy phase depends on a delicate interplay between the network s topology and the relationship between energy and degree of a minimum.   interestingly, the network s degree correlations and the details of the transition rates do not play any role in the existence ( nor in the value ) of the transition temperature, but have an impact only on more involved properties. for glauber or metropolis rates in particular, we find that the low - temperature phase can be further divided into two regions with different scaling properties of the average trapping time.   overall, our results rationalize and link the empirical findings about correlations between the energy of the minima and their degree, and should stimulate further investigations on this issue.
a first principle derivation is given of the neutrino damping rate in real - time thermal field theory.   starting from the discontinuity of the neutrino self energy at the two loop level, the damping rate can be expressed as integrals over space phase of amplitudes squared, weighted with statistical factors that account for the possibility of particle absorption or emission from the medium.   specific results for a background composed of neutrinos, leptons, protons and neutrons are given. additionally, for the real part of the dispersion relation we discuss the relation between the results obtained from the thermal field theory, and those obtained by the thermal average of the forward scattering amplitude.   =.6 in    1=1   '# 1#1i19 i    ^_0.9pt'# 1#1i19 i
there exists a group of persistently faint galactic x - ray sources that, based on their location in the galaxy, high @xmath0, association with x - ray bursts, and absence of low frequency x - ray pulsations, are thought to be low - mass x - ray binaries ( lmxbs ).   we present results from chandra observations for eight of these systems : 4u 1708408, 2s 1711339, ks 1739304, slx 1735269, grs 1736297, slx 1746331, 1e 1746.73224, and 4u 181212.   locations for all sources, excluding grs 1736297, slx 1746331, and ks 1739304 ( which were not detected ) were improved to 0.6  error circles ( 90% confidence ).   our observations support earlier findings of transient behavior of grs 1736 - 297, ks 1739304, slx 1746 - 331, and 2s 1711 - 339 ( which we detect in one of two observations ).   energy spectra for 4u 1708408, 2s 1711339, slx 1735269, 1e 1746.7 - 3224, and 4u 181212 are hard, with power law indices typically 1.4 - 2.1, which are consistent with typical faint lmxb spectra.
higher order corrections in perturbative quantum field theory are required for precise theoretical analysis to investigate new physics beyond the standard model.   this indicates that we need to evaluate feynman loop diagrams with multi - loop integrals which may require multi - precision calculation.   we developed a dedicated accelerator system for multi - precision calculations ( grape9-mpx ).   we present performance results of our system for the case of feynman two - loop box and three - loop selfenergy diagrams with multi - precision.
the task of monte carlo simulation of the evolution of the parton distributions in qcd and of constructing new parton shower monte carlo algorithms requires new way of organizing solutions of the qcd evolution equations, in which quark@xmath0gluon transitions on one hand and quark@xmath0quark or gluon@xmath0gluon transitions ( pure gluonstrahlung ) on the other hand, are treated separately and differently.   this requires certain reorganization of the iterative solutions of the qcd evolution equations and leads to what we refer to as a _ hierarchic iterative solutions _ of the evolution equations.   we present three formal derivations of such a solution.   results presented here are already used in the other recent works to formulate new mc algorithms for the parton - shower - like implementations of the qcd evolution equations.   they are primarily of the non - markovian type.   however, such a solution can be used for the markovian - type mcs as well.   we also comment briefly on the relation of the presented formalism to similar methods used in other branches of physics.   * ifjpan - v-04 - 09 *     * hierarchically organized iterative solutions of the evolution equations in qcd@xmath1 *    * s. jadach, m. skrzypek * _ and _ * z. was * +   +    _ to be submitted to acta physica polonica _   * ifjpan - v-04 - 09 + december  2006 *    @xmath1this work is partly supported by the eu grant mtkd - ct-2004 - 510126 in partnership with the cern physics department and by the polish ministry of scientific research and information technology grant no 620/
treated beyond the single - mode approximation, measurement - induced - nonlocality ( min ) is investigated for both dirac and bosonic fields in non - inertial frames.   two distinctly differences between the dirac and bosonic fields are : ( i ) the min for dirac fields persists for any acceleration, while the quantity for bosonic fields does decay to zero in the infinite acceleration limit ; ( ii ) the dynamic behaviors of the min for dirac fields is quite different from the bosonic fields case. besides, we also study the nonlocality for dirac fields and find that the min is more general than the quantum nonlocality related to violation of bell s inequalities  . meanwhile some discussions of geometric discord are presented too.
this paper presents a spatial global sensitivity analysis ( gsa ) approach in a 2d shallow water equations based high resolution ( hr ) flood model.   the aim of a spatial gsa is to produce sensitivity maps which are based on sobol index estimations.   such an approach allows to rank the effects of uncertain hr topographic data input parameters on flood model output.   the influence of the three following parameters has been studied : the measurement error, the level of details of above - ground elements representation and the spatial discretization resolution. to introduce uncertainty, a probability density function and discrete spatial approach   have been applied to generate @xmath0 dems.   based on a 2d urban flood river event modelling, the produced sensitivity maps highlight the major influence of modeller choices compared to hr measurement errors when hr topographic data are used, and the spatial variability of the ranking.   urban flood ; uncertainties ; shallow water equations ; fullswof_2d ; sensitivity maps ; photogrammetry ; classified topographic data.
the explosion mechanism of broad - lined type ic supernovae ( sne ic - bl ) is not very well understood despite their discovery more than two decades ago. recently a serious confrontation of sne ic - bl with the magnetar ( plus @xmath0ni ) model was carried out following previous suggestions.   strong evidence for magnetar formation was found for the well - observed sne ic - bl 1998bw and 2002ap. in this paper   we systematically study a large sample of sne ic - bl not associated with gamma - ray bursts.   we use photospheric velocity data determined in a self - consistent way, which is an improvement to previous methods that suffered from large inconsistencies.   we find that the magnetar+@xmath1ni model provides a good description of the light curves and velocity evolution of our sample of sne ic - bl, although some sne ( not all ) can also be described by the pure - magnetar model or by the pure-@xmath0ni ( two - component ) model. in the magnetar model,   the amount of @xmath0ni required to explain their luminosity is significantly reduced, and the derived initial explosion energy is, in general, in accordance with neutrino heating.   some correlations between different physical parameters are evaluated and their implications regarding magnetic field amplification and the total energy reservoir are discussed.    # 1 # 1
we establish the existence of fixed points for certain gauge theories candidate to be magnetic duals of qcd with one adjoint weyl fermion. in the perturbative regime of the magnetic theory   the existence of a very large number of fixed points is unveiled.   we classify them by analyzing their basin of attraction.   the existence of several nonsupersymmetric fixed points for the magnetic gauge theory lends further support towards the existence of gauge - gauge duality beyond supersymmetry.   we also discover that among these very many fixed points there are supersymmetric ones emerging from a generic nonsupersymmetric renormalization group flow.   we therefore conclude that supersymmetry naturally emerges as a fixed point theory from a nonsupersymmetric lagrangian without the need for fine - tuning of the bare couplings.   our results suggest that supersymmetry can be viewed as an emergent phenomenon in field theory.   in particular there should be no need for fine - tuning the bare couplings when performing lattice simulations aimed to investigate supersymmetry on the lattice.
in this work we use cosmography to alleviate the degeneracy among cosmological models, proposing a way to parameterize matter and dark energy in terms of cosmokinematics quantities.   the recipe of using cosmography allows to expand observable quantities in taylor series and to directly compare those expansions with data.   we adopt this strategy and we propose a fully self - consistent parametrization of the total energy density driving the late time universe speed up.   afterwards, we describe a feasible _ cosmographic dark energy model _, in which matter is fixed whereas dark energy evolves by means of the cosmographic series.   our technique provides robust constraints on cosmokinematic parameters, permitting one to separately bound matter from dark energy densities.   our cosmographic dark energy model turns out to be one parameter only, but differently from the @xmath0cdm paradigm, it does not contain ansatz on the dark energy form.   in addition, we even determine the free parameter of our model in suitable @xmath1 intervals through monte carlo analyses based on the metropolis algorithm.   we compare our results with the standard concordance model and we find that our treatment seems to indicate that dark energy slightly evolves in time, reducing to a pure cosmological constant only as @xmath2.
in topology inference from data, current approaches face two major problems.   one concerns the selection of a correct parameter to build an appropriate complex on top of the data points ; the other involves with the typical ` large'size of this complex.   we address these two issues in the context of inferring homology from sample points of a smooth manifold of known dimension sitting in an euclidean space @xmath0.   we show that, for a sample size of @xmath1 points, we can identify a set of @xmath2 points ( as opposed to @xmath3 voronoi vertices ) approximating a subset of the medial axis that suffices to compute a distance sandwiched between the well known _ local feature size _ and the local _ weak feature size _   ( in fact, the approximating set can be further reduced in size to @xmath4 ).   this distance, called the _   lean feature size _, helps pruning the input set at least to the level of local feature size while making the data locally uniform.   the local uniformity in turn helps in building a complex for homology inference on top of the sparsified data without requiring any user - supplied distance threshold. unlike most topology inference results, ours does not require that the input is dense relative to a _   global _ feature such as _ reach _ or _ weak feature size _ ; instead it can be adaptive with respect to the local feature size.   we present some empirical evidence in support of our theoretical claims.
we present the _ asca _ results of imaging spectroscopy of the giant molecular cloud sgr  b2.   the x - ray spectrum is found to be very peculiar ; it exhibits a strong emission line at 6.4 kev, a low energy cutoff below about 4 kev and a pronounced edge - structure at 7.1 kev.   the x - ray image is extended and its peak position is shifted from the core of the molecular cloud toward the galactic center by about 12 arcminute. the x - ray spectrum and the morphology   are well reproduced by a scenario that x - rays from an external source located in the galactic center direction are scattered by the molecular cloud sgr  b2, and come into our line of sight. thus sgr  b2 may be called an _ x - ray reflection nebula_. possible implications of the galactic center activity related to this unique source are presented.
we consider langevin dynamics associated with a modified kinetic energy vanishing for small momenta.   this allows us to freeze slow particles, and hence avoid the re - computation of inter - particle forces, which leads to computational gains.   on the other hand, the statistical error may increase since there are a priori more correlations in time.   the aim of this work is first to prove the ergodicity of the modified langevin dynamics ( which fails to be hypoelliptic ), and next to analyze how the asymptotic variance on ergodic averages depends on the parameters of the modified kinetic energy.   numerical results illustrate the approach, both for low - dimensional systems where we resort to a galerkin approximation of the generator, and for more realistic systems using monte carlo simulations.
in this paper the averaged weak ( awec ) and averaged null ( anec ) energy conditions, together with uncertainty principle - type restrictions on negative energy ( `` quantum inequalities '' ), are examined in the context of evaporating black hole backgrounds in both two and four dimensions. in particular, integrals over only half - geodesics are studied.   we determine the regions of the spacetime in which the averaged energy conditions are violated. in all cases where these conditions fail,   there appear to be quantum inequalities which bound the magnitude and extent of the negative energy, and hence the degree of the violation.   the possible relevance of these results for the validity of singularity theorems in evaporating black hole spacetimes is discussed.   = cmbx10 scaled 3    -36pt 0.64 cm 0.64 cm    gr - qc/9506052 + mit - ctp-2446 + tutp-95 - 1 + dec.   11, 1995    averaged energy conditions + and + evaporating black holes +.7 in l.h.   ford +.2 in center for theoretical physics, laboratory for nuclear science + massachusetts institute of technology, cambridge, massachusetts 02139 + 0.1 in and 0.1 in institute of cosmology, department of physics and astronomy + tufts university, medford, massachusetts 02155 + 0.3 in and 0.3 in thomas a. roman +.2 in institute of cosmology, department of physics and astronomy + tufts university, medford, massachusetts 02155 + 0.1 in and 0.1 in department of physics and earth sciences + central connecticut state university, new britain, ct 06050 +
a deep hst image of the ms 2137 - 2353 core has revealed detailed morphological structures in two arc systems, which are modelled and well reproduced after a complete analysis of the lensing properties of the dark matter component.   latter could have a simple elliptical mass distribution with ellipticity and angular orientation similar to those of the visible and x - ray light, which suggests that the ms 2137 - 2353 is a relaxed cluster at z=0.313. the predicted density profile ( @xmath0 @xmath1 @xmath2 with @xmath3 @xmath4 22.5@xmath5 kpc ) within 150@xmath5 kpc implies increasing m / l ratio with the radius, and could be in agreement with predictions from standard cdm simulations.   at least two faint sources ( unlensed magnitude, r=23.9 and 26, respectively ) are aligned with the cluster core and are responsible of the arc systems.   they have been reconstructed with details as small as 0".02 ( or 160@xmath5 pc in the source assumed at z= 1 ), one could be a nearly edge - on barred spiral galaxy, and the other has a more complex morphology, which could be related to a close interacting pair and/or to dust.   they show strong signs of star formation indicated by compact hii regions well off their center.   the observation of giant luminous arcs by hst could even resolve the size of giant hii regions at z@xmath1 1.
weak gravitational lensing provides a direct way to study the mass distribution of clusters of galaxies at large radii.   unfortunately, large scale structure along the line of sight also contributes to the lensing signal, and consequently affects the measurements.   we quantify the effect of distant uncorrelated large scale structure on the inferred mass profile of clusters as measured from weak lensing.   we consider nfw profiles, and find that large scale structure is a major source of uncertainty for most practical situations, when a model, with the mass @xmath0 and the concentration parameter @xmath1 as free parameters, is fit to the observations.   we find that the best constraints are found for clusters at intermediate redshifts @xmath2. for a cluster at @xmath3,   optimal results are obtained when the lensing signal is measured out to @xmath4 arcminutes.   measurements at larger radii do not improve the accuracy with which the profile can be determined, contrary to what is expected when the contribution from large scale structure is ignored. the true uncertainties in @xmath0 and the concentration parameter @xmath1 are @xmath5 times larger than when distant large scale structure is not included in the error budget.   cosmology : gravitational lensing  galaxies : clusters
we consider the rotation of neutrally buoyant axisymmetric particles suspended in isotropic turbulence  . using laboratory experiments as well as numerical and analytical calculations, we explore how particle rotation depends upon particle shape.   we find that shape strongly affects orientational trajectories, but that it has negligible effect on the variance of the particle angular velocity.   previous work has shown that shape significantly affects the variance of the tumbling rate of axisymmetric particles.   it follows that shape affects the spinning rate in a way that is, on average, complementary to the shape - dependence of the tumbling rate.   we confirm this relationship using direct numerical simulations, showing how tumbling rate and spinning rate variances show complementary trends for rod - shaped and disk - shaped particles.   we also consider a random but non - turbulent flow.   this allows us to explore which of the features observed for rotation in turbulent flow are due to the effects of particle alignment in vortex tubes.
the quantum transport through nanoscale junctions is governed by the charging energy @xmath0 of the device.   we employ the recently developed scattering - states numerical renormalization group approach to open quantum systems to study nonequilibrium green s functions and current - voltage characteristics of such junctions for small and intermediate values of @xmath0.   we establish the accuracy of the approach by a comparison with diagrammatic kadanoff - baym - keldysh results which become exact in the weak coupling limit @xmath1.   we demonstrate the limits of the diagrammatic expansions at intermediate values of the charging energy. while the numerical renormalization group approach correctly predicts only one single, universal low - energy scale at zero bias voltage, some diagrammatic expansions yield two different low - energy scales for the magnetic and the charge fluctuations. at large voltages, however, the self - consistent second born as well as the gw approximation reproduce the scattering - states renormalization group spectral functions for symmetric junctions, while for asymmetric junctions the voltage - dependent redistribution of spectral weight differs significantly in the different approaches.   the second - order perturbation theory does not capture the correct single - particle dynamics at large bias and violates current conservation for asymmetric junctions.
this work aims at combining adaptive protocol design, utility maximization and stochastic geometry.   we focus on a spatial adaptation of aloha within the framework of ad hoc networks.   we consider quasi - static networks in which mobiles learn the local topology and incorporate this information to adapt their medium access probability  ( map ) selection to their local environment.   we consider the cases where nodes cooperate in a distributed way to maximize the global throughput or to achieve either proportional fair or max - min fair medium access. in the proportional fair case,   we show that nodes can compute their optimal maps as solutions to certain fixed point equations. in the maximum throughput case  , the optimal maps are obtained through a gibbs sampling based algorithm. in the max min case,   these are obtained as the solution of a convex optimization problem.   the main performance analysis result of the paper is that this type of distributed adaptation can be analyzed using stochastic geometry in the proportional fair case. in this case, we show that, when the nodes form a homogeneous poisson point process in the euclidean plane, the distribution of the optimal map can be obtained from that of a certain shot noise process w.r.t. the node poisson point process and that the mean utility can also be derived from this distribution.   we discuss the difficulties to be faced for analyzing the performance of the other cases ( maximal throughput and max - min fairness ).   numerical results illustrate our findings and quantify the gains brought by spatial adaptation in such networks.
the _ cobe _ firas data contain foreground emission from interplanetary, galactic interstellar dust and extragalactic background emission.   we use three different methods to separate the various emission components, and derive the spectrum of the extragalactic far infrared background ( firb ).   each method relies on a different set of assumptions, which affect the firb spectrum in different ways. despite this,   the firb spectra derived by these different methods are remarkably similar.   the average spectrum that we derive in the @xmath0@xmath1 ( 2000 -125 ) frequency interval is : @xmath2k ), where @xmath3@xmath1 ( @xmath4 ) and @xmath5 is the planck function.   the derived firb spectrum is consistent with the dirbe 140 and 240   detections.   the total intensity received in the 5 - 80  @xmath1 frequency interval is 14 nw m@xmath6 sr@xmath7, and comprises about 20% of the total intensity expected from the energy release from nucleosynthesis throughout the history of the universe.   # 1    = 10000    = 1000
bloch oscillations appear for a particle in a weakly tilted periodic potential.   the intrinsic spin hall effect is an outcome of a spin - orbit coupling.   we demonstrate that both these phenomena can be realized simultaneously in a gas of weakly interacting ultracold atoms exposed to a tilted optical lattice and to a set of spatially dependent light fields inducing an effective spin - orbit coupling.   it is found that both the spin hall as well as the bloch oscillation effects may coexist, showing, however, a strong correlation between the two.   these correlations are manifested as a transverse spin current oscillating in - phase with the bloch oscillations. on top of the oscillations originating from the periodicity of the model,   a trembling motion is found which is believed to be atomic _ zitterbewegung_. it is argued that damping of these zitterbewegung oscillations may to a large extent be prevented in the present setup considering a periodic optical lattice potential.
in this paper the structure properties of asymmetrical nuclear matter has been calculated employing @xmath0 potential for different values of proton to neutron ratio.   these calculations have been also made for the case of symmetrical nuclear matter with @xmath1, @xmath2 and @xmath0 potentials. in our calculations  , we use the lowest order constrained variational ( locv ) method to compute the correlation function of the system.
we present here numerical hydrodynamic simulations of line - driven accretion disk winds in cataclysmic variable systems.   we calculate wind mass - loss rate, terminal velocities, and line profiles for ( 1550   ) for various viewing angles.   the models are 2.5-dimensional, include an energy balance condition, and calculate the radiation field as a function of position near an optically thick accretion disk.   the model results show that centrifugal forces produce collisions of streamlines in the disk wind which in turn generate an enhanced density region, underlining the necessity of two dimensional calculations where these forces may be represented. for disk luminosity @xmath0, white dwarf mass @xmath1, and white dwarf radii @xmath2, we obtain a wind mass - loss rate of @xmath3, and a terminal velocity of @xmath4.   the line profiles we obtain are consistent with observations in their general form, in particular in the maximum absorption at roughly half the terminal velocity for the blue - shifted component, in the magnitudes of the wind velocities implied by the absorption components, in the fwhm of the emission components, and in the strong dependence in inclination angle.
over the past few years it has been discovered that an `` observable '' can be set up on the lattice which obeys the discrete cauchy - riemann equations.   the ensuing condition of discrete holomorphicity leads to a system of linear equations which can be solved to yield the boltzmann weights of the underlying lattice model.   surprisingly, these are the well known boltzmann weights which satisfy the star - triangle or yang - baxter equations at criticality. this connection has been observed for a number of exactly solved models.   i briefly review these developments and discuss how this connection can be made explicit in the context of the z@xmath0 model.   i also discuss how discrete holomorphicity has been used in recent breakthroughs in the rigorous proof of some key results in the theory of planar self - avoiding walks.
weak radiative decay @xmath0 is known to be a loop - generated process.   however, it does receive tree - level contributions from ckm - suppressed @xmath1 transitions. in the present paper  , we evaluate such contributions together with similar ones from the qcd penguin operators. for a low value of the photon energy cutoff @xmath2 that has often been used in the literature  , they can enhance the inclusive branching ratio by more than 10%. for @xmath3gev or higher  , the effect does not exceed @xmath4, which is due to phase - space suppression.   our perturbative results contain collinear logarithms that depend on the light quark masses @xmath5   ( @xmath6 ).   we have allowed @xmath7 to vary from 10 to 50, which corresponds to values of @xmath5 that are typical for the constituent quark masses.   such a rough method of estimation may be improved in the future with the help of fragmentation functions once the considered effects begin to matter in the overall error budget for @xmath8.
we report on the long - term evolution of the spin period of the symbiotic x - ray pulsar gx  1 + 4 and a possible interpretation within a model of quasi - spherical accretion.   new period measurements from bepposax, integral and fermi observations have been combined with previously published data from four decades of observations. during   the 1970 s gx  1 + 4 was spinning up with the fastest rate among the known x - ray pulsars at the time. in the mid 1980 s it underwent a change during a period of low x - ray flux and started to spin down with a rate similar in magnitude to the previous spin up rate.   the spin period has changed from @xmath0110  s to @xmath0160  s within the last three decades.   our results demonstrate that the overall spin down trend continues and is stronger than ever.   we compare the observations with predictions from a model assuming quasi - spherical accretion from the slow wind of the m giant companion.
gravitinos and hidden sector fields often cause a cosmological disaster in supersymmetric models. we find that a model with gravitational gauge mediation solves such a problem quite naturally.   the @xmath0-problem is also absent in the model.   moreover, the abundance of gravitinos explains correct amount of dark matter of the universe.   the dark matter abundance can be calculated without detailed information on the thermal history of the universe such as the reheating temperature after inflation.    slac - pub-12189 + hep - ph/0611111 +    * gauge mediation in supergravity + and gravitino dark matter * +   +    _ stanford linear accelerator center, stanford university, stanford, ca 94309 and _ + _ physics department, stanford university, stanford, ca 94305 _
we investigate the location of the radio jet bases ( `` radio cores '' ) of blazars in radio images, and their stationarity by means of dense very long baseline interferometry ( vlbi ) observations. in order to measure the position of a radio core  , we conducted 12 epoch astrometric observation of the blazar markarian 421 with the vlbi exploration of radio astrometry at 22 ghz immediately after a large x - ray flare, which occurred in the middle of 2011 september.   for the first time, we find that the radio core is not stationary but rather changes its location toward 0.5 mas downstream.   this angular scale corresponds to the de - projected length of a scale of @xmath0 schwarzschild radii ( @xmath1 ) at the distance of markarian  421.   this radio - core wandering may be a new type of manifestation associated with the phenomena of large x - ray flares.
with the great success in simulating many intelligent behaviors using computing devices, there has been an ongoing debate whether all conscious activities are computational processes. in this paper, the answer to this question is shown to be no.   a certain phenomenon of consciousness is demonstrated to be fully represented as a computational process using a quantum computer.   based on the computability criterion discussed with turing machines, the model constructed is shown to necessarily involve a non - computable element. the concept that this is solely a quantum effect and does not work for a classical case is also discussed.
the dynamics of the recombination in ultrastrong atomic fields is studied for one - dimensional models by numerical simulations.   a nonmonotonic behavior of the bound state final population as a function of the laser field amplitude is examined.   an important role of a slow drift of an electron wave packet is observed.
we have performed inelastic magnetic neutron scattering experiments on @xmath0 ( @xmath1 and @xmath2 ) in order to study the nd 4f  spin dynamics at low energies ( @xmath3 ). in all samples we find at high temperatures a quasielastic line ( lorentzian ) with a line width which decreases on lowering the temperature.   the temperature dependence of the quasielastic line width @xmath4 can be explained with an orbach  process, i.e. a relaxation via the coupling between crystal field excitations and phonons. at low temperatures   the nd4f magnetic response @xmath5 correlates with the electronic properties of the @xmath6layers. in the insulator @xmath7 ( @xmath8 ) the quasielastic line vanishes below 80  k and an inelastic   excitation occurs.   this directly indicates the splitting of the @xmath9 ground state kramers doublet due to the static antiferromagnetic order of the cu moments. in @xmath10 with x = 0.12, 0.15 and @xmath11 with x = 0.1, 0.12, 0.15, 0.18 superconductivity   is strongly suppressed. in these compounds   we observe a temperature independent broad quasielastic line of gaussian shape below @xmath12.   this suggests a distribution of various internal fields on different nd sites and is interpreted in the frame of the stripe model. in @xmath13 ( @xmath14 )   such a quasielastic broadening is not observed even at lowest temperature.   0.25 cm 0.25 cm -1 cm -1 cm 24.5 cm    physical review b to be published 1 october 1999    2
an interpretation of the beam spin azimuthal asymmetries measured at jlab in deep exclusive electroproduction of charged and neutral pions is presented.   the model combines a regge pole approach with the effect of nucleon resonances.   the @xmath0- and @xmath1-channel contributions are described using a dual bloom - gilman connection between the exclusive form factors and inclusive deep inelastic structure functions.   the results are in agreement with data provided the excitations of nucleon resonances are taken into account.
we propose a scenario in which the dark components of the universe are manifestations of a single bulk viscous fluid.   using dynamical system methods, a qualitative study of the homogeneous, isotropic background scenario is performed in order to determine the phase space of all possible solutions. the specific model which we investigate shares similarities with a generalized chaplygin gas in the background but is characterized by non - adiabatic pressure perturbations.   this model is tested against supernova type ia and matter power spectrum data.   different from other unified descriptions of dark matter and dark energy, the matter power spectrum is well behaved, i.e., there are no instabilities or oscillations on small perturbation scales.   the model is competitive in comparison with the currently most popular proposals for the description of the cosmological dark sector.
the one - dimensional free fermi gas is a prototype conformally invariant system, whose entanglement properties are well - understood. in this work,   the effects of a single impurity on one dimensional free fermion entanglement entropy are studied both analytically and numerically.   such an impurity represents an exactly marginal perturbation to the bulk conformally invariant fixed point.   we find that the impurity leads to sub - leading contributions to the entanglement entropy that scale inversely with the subsystem size.   the origin of such contributions are identified.
despite intense interest and considerable works, definitive experimental evidence for time reversal invariant topological superconductivity is still lacking. hence searching for such superconductivity in real materials remains one of the main challenges in the field of topological material.   previously it has been shown that in the buckled honeycomb lattice structure, hydrogenated single bilayer bi, namely bih, is a topological insulator. here   we predict that upon n - type doping, bih is a time reversal invariant topological superconductor.   interestingly the edge states of such superconductor consists of both helical complex fermion modes and helical majorana fermion modes.
coherent epitaxial growth allows to produce strained crystalline films with structures which are unstable in the bulk.   thereby, the overlayer lattice parameters in the interface plane, @xmath0, determine the minimum - energy out - of - plane lattice parameter, @xmath1.   we show by means of density - functional total energy calculations that this dependence can be discontinuous and predict related first - order phase transitions in strained tetragonal films of the elements v, nb, ru, la, os, and ir.   the abrupt change of @xmath2 can be exploited to switch properties specific to the overlayer material.   this is demonstrated for the example of the superconducting critical temperature of a vanadium film which we predict to jump by 20% at a discontinuity of @xmath2.
we present a method to include stereoscopic information about the three dimensional structure of flux tubes into the reconstruction of the coronal magnetic field. due to the low plasma beta in the corona   we can assume a force free magnetic field, with the current density parallel to the magnetic field lines.   here we use linear force free fields for simplicity.   the method uses the line of sight magnetic field on the photosphere as observational input.   the value of @xmath0 is determined iteratively by comparing the reconstructed magnetic field with the observed structures.   the final configuration is the optimal linear force solution constrained by both the photospheric magnetogram and the observed plasma structures. as an example   we apply our method to soho mdi / eit data of an active region. in the future   it is planned to apply the method to analyse data from the secchi instrument aboard the stereo mission.
the vlti is the ideal instrument for measuring the distances of nearby cepheids with the baade - wesselink method, allowing an accurate recalibration of the cepheid period - luminosity relation.   the high accuracy required by such measurement, however, can only be reached taking into account the effects of limb darkening, and its dependence on the cepheid pulsations.   we present here our new method to compute phase- and wavelength - dependent limb darkening profiles, based on hydrodynamic simulation of classical cepheid atmospheres.
we analyze a systematic algorithm for the exact computation of the current cumulants in stochastic nonequilibrium systems, recently discussed in the framework of full counting statistics for mesoscopic systems.   this method is based on identifying the current cumulants from a rayleigh - schrdinger perturbation expansion for the generating function.   here it is derived from a simple path - distribution identity and extended to the joint statistics of multiple currents. for a possible thermodynamical interpretation  , we compare this approach to a generalized onsager - machlup formalism.   we present calculations for a boundary driven kawasaki dynamics on a one - dimensional chain, both for attractive and repulsive particle interactions.
multivariate associated kernel estimators, which depend on both target point and bandwidth matrix, are appropriate for partially or totally bounded distributions and generalize the classical ones as gaussian.   previous studies on multivariate associated kernels have been restricted to product of univariate associated kernels, also considered having diagonal bandwidth matrices.   however, it is shown in classical cases that for certain forms of target density such as multimodal, the use of full bandwidth matrices offers the potential for significantly improved density estimation. in this paper, general associated kernel estimators with correlation structure   are introduced.   properties of these estimators are presented ; in particular, the boundary bias is investigated.   then, the generalized bivariate beta kernels are handled with more details.   the associated kernel with a correlation structure is built with a variant of the mode - dispersion method and two families of bandwidth matrices are discussed under the criterion of cross - validation.   several simulation studies are done. in the particular situation of bivariate beta kernels,   it is therefore pointed out the very good performance of associated kernel estimators with correlation structure compared to the diagonal case. finally, an illustration on real dataset of paired rates in a framework of political elections is presented.   asymmetric kernel, boundary bias, correlation structure, bandwidth matrix, nonparametric estimation, mode - dispersion. :   62g07(08 ) ; 62h12    * short running title * : multivariate associated kernels
we prove that every spherical football is a branched cover, branched only in the vertices, of the standard football made up of @xmath0 pentagons and @xmath1 hexagons.   we also give examples showing that the corresponding result is not true for footballs of higher genera.   moreover, we classify the possible pairs @xmath2 for which football patterns on the sphere exist satisfying a natural generalisation of the usual incidence relation between pentagons and hexagons to @xmath3-gons and @xmath4-gons.
in this paper we provide a unified treatment of some convex minimization problems, which allows for a better understanding and, in some cases, improvement of results in this direction proved recently in spaces of curvature bounded above. for this purpose  , we analyze the asymptotic behavior of compositions of finitely many firmly nonexpansive mappings in the setting of @xmath0-uniformly convex geodesic spaces focusing on asymptotic regularity and convergence results.   + _ keywords : _ firmly nonexpansive mapping, convex optimization, convex feasibility problem, @xmath0-uniformly convex geodesic space, cat@xmath1 space    @xmath2departamento de anlisis matemtico - imus, universidad de sevilla, apdo. de correos 1160, 41080 sevilla, spain   + @xmath3department of mathematics, babe - bolyai university, koglniceanu 1, 400084 cluj - napoca, romania   + @xmath4simion stoilow institute of mathematics of the romanian academy, research group of the project pd-3 - 0152, + p.o.   box 1 - 764, ro-014700 bucharest, romania +   + e - mail addresses : dariza@us.es ( d. ariza - ruiz ), glopez@us.es ( g. lpez - acedo ), anicolae@math.ubbcluj.ro ( a. nicolae )
we present time - resolved photometry of two cataclysmic variables whose ccd photometric observations were obtained with the 1 m telescope at the south african astronomical observatory in october 2002 and august 2003 and with the 1 m telescope at hoher list in germany.   + concerning mct 2347 - 3144 we detect for the first time a period of 6.65h. for v1193 ori the 3.96 h periodicity has for the first time been confirmed through time - resolved photometry.
we investigate the dynamical importance of a newly recognized possible source of significant feedback generated during structure formation ; namely cosmic ray ( cr ) pressure.   we present evidence for the existence of numerous shocks in the hot gas of galaxy clusters ( gcs ).   we employ for the first time an explicit numerical treatment of cr acceleration and transport in hydro simulations of structure formation. according to our results,   crs provide an important fraction of the total pressure inside gcs, up to several tenths.   this was true even at high redshift ( z=2 ), meaning that such non - thermal component could affect the evolution of structure formation.
dynamical friction arises from the interaction of a perturber and the gravitational wake it excites in the ambient medium. this interaction is usually derived assuming that the perturber has a constant velocity. in realistic situations,   motion is accelerated as for instance by dynamical friction itself. here, we study the effect of acceleration on the dynamical friction force.   we characterize the density enhancement associated with a constantly accelerating perturber with rectilinear motion in an infinite homogeneous gaseous medium and show that dynamical friction is not a local force and that its amplitude may depend on the perturber s initial velocity.   the force on an accelerating perturber is maximal between mach 1 and mach 2, where it is smaller than the corresponding uniform motion friction. in the limit where the perturber s size is much smaller than the distance needed to change the mach number by unity through acceleration, a subsonic perturber feels a force similar to uniform motion friction only if its past history does not include supersonic episodes.   once an accelerating perturber reaches large supersonic speeds, accelerated motion friction is marginally stronger than uniform motion friction.   the force on a decelerating supersonic perturber is weaker than uniform motion friction as the velocity decreases to a few times the sound speed.   dynamical friction on a decelerating subsonic perturber with an initial mach number larger than 2 is much larger than uniform motion friction and tends to a finite value as the velocity vanishes in contrast to uniform motion friction.       hydrodynamics  ism : general
the spontaneously generated magnetic flux observed by mannhart _ et.   al.  _   ( 1996 ) in asymmetric @xmath0 grain boundaries in yba@xmath1cu@xmath2o@xmath3 was explained by them in terms of a @xmath4 superconducting order parameter and grain boundary faceting.   this article argues that twin boundaries which contact the grain boundary also play an important role.
we study the behavior of simple principal pivoting methods for the p - matrix linear complementarity problem ( p - lcp ).   we solve an open problem of morris by showing that murty s least - index pivot rule ( under any fixed index order ) leads to a quadratic number of iterations on morris s highly cyclic p - lcp examples.   we then show that on k - matrix lcp instances, _ all _ pivot rules require only a linear number of iterations.   as the main tool, we employ _ unique - sink orientations _ of cubes, a useful combinatorial abstraction of the p - lcp.
we review the bogoliubov theory in the context of recent experiments, where atoms are scattered from a bose - einstein condensate into two well - separated regions.   we find the full dynamics of the pair - production process, calculate the first and second order correlation functions and show that the system is ideally number - squeezed.   we calculate the fisher information to show how the entanglement between the atoms from the two regions changes in time.   we also provide a simple expression for the lower bound of the useful entanglement in the system in terms of the average number of scattered atoms and the number of modes they occupy.   we then apply our theory to a recent `` twin - beam '' experiment [ r. bcker _ et al.   _, nat  . phys.   * 7 *, 608 ( 2011 ) ]  . the only numerical step of our semi - analytical description can be easily solved and does not require implementation of any stochastic methods.
the baryon asymmetry, together with a dark matter asymmetry, may be produced during a first order phase transition in a generative sector.   we study the possibility of a gravitational wave signal in a model realising such a scenario.   we identify areas of parameter space with strong phase transitions which can be probed by future, space based, gravitational wave detectors.   other signals of this scenario include collider signatures of a @xmath0, dm self interactions, a contribution to @xmath1 and nuclear recoils at direct detection experiments.   desy 17 - 021 + february 22, 2017    * *    * iason baldes *    _ desy, notkestrae 85, d-22607 hamburg, germany _  .3 cm    iason.baldes@desy.de
the calculation of a segment of eigenvalues and their corresponding eigenvectors of a hermitian matrix or matrix pencil has many applications.   a new density - matrix - based algorithm has been proposed recently and a software package feast has been developed.   the density - matrix approach allows feast s implementation to exploit a key strength of modern computer architectures, namely, multiple levels of parallelism.   consequently, the software package has been well received, especially in the electronic structure community.   nevertheless, theoretical analysis of feast has lagged.   for instance, the feast algorithm has not been proven to converge.   this paper offers a detailed numerical analysis of feast.   in particular, we show that the feast algorithm can be understood as an accelerated subspace iteration algorithm in conjunction with the rayleigh - ritz procedure.   the novelty of feast lies in its accelerator which is a rational matrix function that approximates the spectral projector onto the eigenspace in question.   analysis of the numerical nature of this approximate spectral projector and the resulting subspaces generated in the feast algorithm establishes the algorithm s convergence.   this paper shows that feast is resilient against rounding errors and establishes properties that can be leveraged to enhance the algorithm s robustness.   finally, we propose an extension of feast to handle non - hermitian problems and suggest some future research directions.   generalized eigenvalue problem, subspace iteration, spectral projection    15a18, 65f15
we survey geometric properties which imply the stochastic incompleteness of the minimal diffusion process associated to the laplacian on manifolds and graphs.   in particular, we completely characterize stochastic incompleteness for spherically symmetric graphs and show that, in contrast to the case of riemannian manifolds, there exist examples of stochastically incomplete graphs of polynomial volume growth.
we propose and analyze a model for phase transitions in an inhomogeneous fluid membrane, that couples local composition with curvature nonlinearly. for asymmetric membranes,   our model shows generic non - ising behavior and the ensuing phase diagram displays either a first- or a second - order phase transition through a critical point ( cp ) or a tricritical point ( tp ), depending upon the bending modulus.   it predicts generic nontrivial enhancement in fluctuations of asymmetric membranes that scales with system size in a power law fashion at the cp and tp in two dimensions, not observed in symmetric membranes.   it also yields two - dimensional ising universality class for symmetric membranes, in agreement with experimental results.
an optical imaging study of recent 30 novae has been undertaken using both ground - based and space - based observations.   resolved shells have been detected around 9 objects in the ground - based data, while another four objects have shells detected by _   hubble space telescope _   observations ; for rw  umi, we fail to detect a shell which was observed five years earlier.   images in h@xmath0, and when appropriate   @xmath15007, are shown, and finding charts for novae without shells are given if no published chart is available.   expansion parallaxes for all systems with shells are derived, and absolute magnitudes for a total of 28 objects are presented, along with a discussion of the maximum magnitude - rate of decline relation.   we find that separate linear fits for fast and slow novae may be a better representation of the data than a single, global fit. at minimum,   most novae have similar magnitudes as those of dwarf novae at maximum and novalike stars.
we show that the multiple teleportation protocol ( mtp ) given in ref.   [ phys.   rev. lett. * 100 *, 110503 ( 2008 ) ] is not restricted to the knill - laflamme - milburn ( klm ) framework.   rather, we show that mtp can be implemented using any teleportation scheme.   we also present two new mtp s which, under certain situations, are more efficient than the original one, requiring half of the number of its teleportations to achieve at least the same probability of success ( @xmath0 ).   one of the protocols, however, uses less entanglement than the others yielding, surprisingly, the greatest @xmath0.
if a gravitational microlensing event is caused by a widely separated binary lens and the source approaches both lens components, the source flux is successively magnified by the individual lenses : double microlensing events. if events are observed astrometrically, double lensing events are expected to occur with an increased frequency due to the long range astrometric effect of the companion.   we find that although the trajectory of the source star image centroid shifts of an astrometric double lensing event has a distorted shape from both of the elliptical ones induced by the individual single lens components, event duplication can be readily identified by the characteristic loop in the trajectory formed during the source s passage close to the companion.   we determine and compare the probabilities of detecting double lensing events from both photometric and astrometric lensing observations by deriving analytic expressions for the relations between binary lensing parameters to become double lensing events. from this determination  , we find that for a given set of the binary separation and the mass ratio the astrometric probability is roughly an order higher than the photometric probability.   therefore, we predict that a significant fraction of events that will be followed up by using future high precision interferometeric instruments will be identified as double lensing events.
* gibbs - ringing is a well known artifact which manifests itself as spurious oscillations in the vicinity of sharp image transients, e.g. at tissue boundaries.   the origin can be seen in the truncation of k - space during mri data - acquisition.   consequently, correction techniques like gegenbauer reconstruction or extrapolation methods aim at recovering these missing data. here  , we present a simple and robust method which exploits a different view on the gibbs - phenomena.   the truncation in k - space can be interpreted as a convolution with a sinc - function in image space.   hence, the severity of the artifacts depends on how the sinc - function is sampled.   we propose to re - interpolate the image based on local, subvoxel shifts to sample the ringing pattern at the zero - crossings of the oscillating sinc - function. with this, the artifact can effectively and robustly be removed with a minimal amount of smoothing. *    key words : gibbs - ringing | ringing - artifact | truncation - artifact
we have quantified the average filamentarity of the galaxy distribution in seven nearly two dimensional strips from the sdss dr5 using a volume limited sample in the absolute magnitude range @xmath0.   the average filamentarity of star forming ( sf ) galaxies, which are predominantly blue, is found to be more than that of other galaxies which are predominantly red.   this difference is possibly an outcome of the fact that blue galaxies have a more filamentary distribution. comparing the sf galaxies with only the blue other galaxies, we find that the two show nearly equal filamentarity. separately analyzing the galaxies with high star formation rates ( sfr ) and low sfr, we find that the latter has a more filamentary distribution.   we interpret this in terms of two effects ( 1. )   a correlation between the sfr and individual galaxy properties like luminosity with the high sfr galaxies being more luminous ( 2. ) a relation between the sfr and environmental effects like the density with the high sfr galaxies preferentially occurring in high density regions.   these two effects are possibly not independent and are operating simultaneously.   we do not find any difference in the filamentarity of sf galaxies and agns.   methods : numerical - galaxies : statistics - cosmology : theory - cosmology : large scale structure of universe
we investigate the statistical evolution of magnetic neutron stars recycled in low mass binary ( lmb ) systems, simulating synthetic populations.   irrespective to the details of the physical models, we find to be significant the fraction of neutron stars spinning close to their mass shedding limit relative to the millisecond pulsar population.   the simulated neutron stars show a tail in their period distribution at periods shorter than 1.558 ms, the minimum detected so far.   crustal magnetic field decay models predict also the existence of massive rapidly spinning neutron stars with very low magnetic moment.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
the results of speckle interferometric observations at the soar telescope in 2014 are given.   a total of 1641 observations were taken, yielding 1636 measurements of 1218 resolved binary and multiple stars and 577 non - resolutions of 441 targets.   we resolved for the first time 56 pairs, including some nearby astrometric or spectroscopic binaries and ten new subsystems in previously known visual binaries.   the calibration of the data is checked by linear fits to the positions of 41 wide binaries observed at soar over several seasons.   the typical calibration accuracy is 01 in angle and 0.3% in pixel scale, while the measurement errors are on the order of 3mas.   the new data are used here to compute 194 binary - star orbits, 148 of which are improvements on previous orbital solutions and 46 are first - time orbits.
we cross correlate the _ wilkinson microwave anisotropy probe _ ( _ wmap _ ) first year data and the diffuse gamma - ray intensity maps from the _ energetic gamma ray experiment telescope _   ( _ egret _ ) using spherical wavelet approaches.   correlations at @xmath0 significance level have been detected, at scales around @xmath1 in the _ wmap _ foreground cleaned w - band and q - band maps, based on data from regions that are outside the most conservative _ wmap _ foreground mask ; no significant correlation is found with the tegmark cleaned map.   the detected correlation is most likely of galactic origin, and thus can help us probing the origins of possible galactic foreground residuals and ultimately removing them from measured microwave sky maps.
new, superfluid specific additive integral of motion is found.   this facilitates investigation of general thermodynamic equilibrium conditions for superfluid.   the analysis is performed in an extended space of thermodynamic variables containing ( along with the usual thermodynamic coordinates such as pressure and temperature ) superfluid velocity and momentum density.   the equilibrium stability conditions lead to thermodynamic inequalities which replace the landau superfluidity criterion at finite temperatures.   key words : superfluidity, thermodynamics, critical velocity
we positionally match sources observed by the sloan digital sky survey ( sdss ), the two micron all sky survey ( 2mass ), and the faint images of the radio sky at twenty - cm ( first ) survey.   practically all 2mass sources are matched to an sdss source within 2 arcsec ; @xmath011% of them are optically resolved galaxies and the rest are dominated by stars.   about 1/3 of first sources are matched to an sdss source within 2 arcsec ; @xmath080% of these are galaxies and the rest are dominated by quasars.   based on these results, we project that by the completion of these surveys the matched samples will include about 10@xmath1 stars and 10@xmath2 galaxies observed by both sdss and 2mass, and about 250,000 galaxies and 50,000 quasars observed by both sdss and first. here   we present a preliminary analysis of the optical, infrared and radio properties for the extragalactic sources from the matched samples.   in particular, we find that the fraction of quasars with stellar colors missed by the sdss spectroscopic survey is probably not larger than 10%, and that the optical colors of radio - loud quasars are 0.05 mag.   redder ( with @xmath3 significance ) than the colors of radio - quiet quasars.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in    # 1@xmath4 # 1@xmath5 # 1    @xmath6    # 1 ( comment : # 1 ) u i
we simultaneously analyze vector and axial - vector spectral functions in vacuum using hadronic models constrained by experimental data and the requirement that weinberg - type sum rules are satisfied. upon explicit inclusion of an excited vector state, _ viz.   _ @xmath0, and the requirement that the perturbative continua are degenerate in vector and axial - vector channels, we deduce the existence of an excited axial - vector resonance state, @xmath1, in order that the weinberg sum rules are satisfied.   the resulting spectral functions are further tested with qcd sum rules.
we investigate percolation in binary and ternary mixtures of patchy colloidal particles theoretically and using monte carlo simulations.   each particle has three identical patches, with distinct species having different types of patch.   theoretically we assume tree - like clusters and calculate the bonding probabilities using wertheim s first - order perturbation theory for association. for ternary mixtures we find up to eight fundamentally different percolated states.   the states differ in terms of the species and pairs of species that have percolated.   the strongest gel is a trigel or tricontinuous gel, in which each of the three species has percolated.   the weakest gel is a mixed gel in which all of the particles have percolated, but none of the species percolates by itself.   the competition between entropy of mixing and internal energy of bonding determines the stability of each state.   theoretical and simulation results are in very good agreement.   the only significant difference is the temperature at the percolation threshold, which is overestimated by the theory due to the absence of closed loops in the theoretical description.
we investigate the dynamics and afterglow light curves of gamma - ray burst ( grb ) blast waves that encounter various density structures ( such as bumps, voids, or steps ) in the surrounding ambient medium.   we present and explain the characteristic response features that each type of density structures in the medium leaves on the forward shock ( fs ) and reverse shock ( rs ) dynamics, for blast waves with either a long - lived or short - lived rs.   we show that, when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration ( even during their deceleration stage ), due to adiabatic cooling of blast waves. comparing numerical examples that have different shapes of bumps or voids,   we propose a number of consistency tests that correct modeling of blast waves needs to satisfy.   our model results successfully pass these tests. employing a lagrangian description of blast waves  , we perform a sophisticated calculation of afterglow emission.   we show that, as a response to density structures in the ambient medium, the rs light curves produce more significant variations than the fs light curves. some observed features ( such as re - brightenings, dips, or slow wiggles )   can be more easily explained within the rs model.   we also discuss on the origin of these different features imprinted on the fs and rs light curves.
the exact formulation of multi - configuration density - functional theory ( dft ) is discussed in this work. as an alternative to range - separated methods, where electron correlation effects are split in the coordinate space, the combination of configuration interaction methods with orbital occupation functionals   is explored at the formal level through the separation of correlation effects in the orbital space. when applied to model hamiltonians  , this approach leads to an exact site - occupation embedding theory ( soet ).   an adiabatic connection expression is derived for the complementary bath functional and a comparison with density matrix embedding theory ( dmet ) is made.   illustrative results are given for the simple two - site hubbard model.   soet is then applied to a quantum chemical hamiltonian, thus leading to an exact complete active space site - occupation functional theory ( cassoft ) where active electrons are correlated explicitly within the cas and the remaining contributions to the correlation energy are described with an orbital occupation functional.   the computational implementation of soet and cassoft as well as the development of approximate functionals are left for future work.    density - functional theory, range separation, multi - configurational methods, site - occupation embedding theory, strongly correlated systems.
upon the discovery of power laws @xcite, a large body of work in complex network analysis has focused on developing generative models of graphs which mimick real - world network properties such as skewed degree distributions @xcite, small diameter @xcite and large clustering coefficients @xcite.   most of these models belong either to the stochastic, e.g., @xcite, or the strategic e.g., @xcite, family of network formation models.   despite the fact that planar graphs arise in numerous real - world settings, e.g., in road and railway maps, in printed circuits, in chemical molecules, in river networks @xcite, comparably less attention has been devoted to the study of planar graph generators. in this work   we analyze basic properties of random apollonian networks @xcite, a popular stochastic model which generates planar graphs with power law properties.   specifically, let @xmath0 be a constant and @xmath1 be the degrees of the @xmath0 highest degree vertices.   we prove that at time @xmath2, for any function @xmath3 with @xmath4 as @xmath5, @xmath6 and for @xmath7, @xmath8 with high probability ( _ whp _  ).   then, we show that the @xmath0 largest eigenvalues of the adjacency matrix of this graph satisfy @xmath9 _ whp _ . furthermore, we prove a refined upper bound on the asymptotic growth of the diameter, i.e., that _ whp _  the diameter @xmath10 at time @xmath2 satisfies @xmath11 where @xmath12 is the unique solution greater than 1 of the equation @xmath13.   finally, we investigate other properties of the model.
we study a model of opinion formation where the collective decision of group is said to happen if the fraction of agents having the most common opinion exceeds a threshold value, a _   critical mass_. we find that there exists a unique, non - trivial critical mass giving the most efficient convergence to consensus.   in addition, we observe that for small critical masses, the characteristic time scale for the relaxation to consensus splits into two.   the shorter time scale corresponds to a direct relaxation and the longer can be explained by the existence of intermediate, metastable states similar to those found in [ p.  chen and s.  redner, phys.   rev.   e * 71 *, 036101 ( 2005 ) ].   this longer time - scale is dependent on the precise condition for consensus  with a modification of the condition it can go away.
we present 21 cm hi line observations of 5@xmath01 square degrees centered on the local abell cluster 1367 obtained as part of the arecibo galaxy environment survey.   one hundred sources are detected ( 79 new hi measurements and 50 new redshifts ), more than half belonging to the cluster core and its infalling region. combining the hi data with sdss optical imaging we show that our hi selected sample follows scaling relations similar to the ones usually observed in optically selected samples.   interestingly all galaxies in our sample appear to have nearly the same baryon fraction independently of their size, surface brightness and luminosity.   the most striking difference between hi and optically selected samples resides in their large scale distribution : whereas optical and x - ray observations trace the cluster core very well, in hi there is almost no evidence of the presence of the cluster.   some implications on the determination of the cluster luminosity function and hi distribution for samples selected at different wavelength are also discussed.       surveys  galaxies : clusters : individual:(a1367 )  galaxies : evolution  galaxies : peculiar  radio lines : galaxies
this paper summarizes the observations which provide the best evidence for the presence of black holes in active galactic nuclei.   this includes : x  ray variability ; kinematical studies using optical emission lines as well as the distribution of megamaser spots ; and the shape of the fe k@xmath0 x  ray emission line.   it also presents the current status of our understanding of jet - dominated active galaxies ( blazars ), and briefly reviews the currently popular agn `` unification schemes '' based on orientation effects.   finally, it reviews the observations of the x  ray and @xmath1ray continuum, which, at least for the radio - quiet objects, is likely to be the primary form of their radiative output, and summarizes the best current models for the radiative processes responsible for the high - energy electromagnetic emission in radio - quiet agn, as well as in jet - dominated blazars.    * to appear in _ theory of black hole accretion disks, _ *    * m. abramowicz, g. bjornsson, & j. pringle, eds.   ( cambridge university press ) *    0.4 cm
as technological advances allow us to fabricate smaller autonomous self - propelled devices, it is clear that at some point directed propulsion could not come from pre - specified deterministic periodic deformation of the swimmer s body and we need to develop strategies to extract a net directed motion from a series of random transitions in the conformation space of the swimmer.   we present a theoretical formulation to describe the `` stochastic motor '' that drives the motion of low reynolds number swimmers based on this concept, and use it to study the propulsion of a simple low reynolds number swimmer, namely, the three - sphere swimmer model.   when the detailed - balanced is broken and the motor is driven out of equilibrium, it can propel the swimmer in the required direction.   the formulation can be used to study optimal design strategies for molecular - scale low reynolds number swimmers.
we present the results of a wide  field survey for extremely red objects ( eros hereafter ), the widest so far, based on @xmath0 and @xmath1 band imaging.   the survey covers 701 arcmin@xmath2 and it is 85% complete to @xmath3 over the whole area and to @xmath4 over 447.5 arcmin@xmath2.   thanks to the wide field covered, a complete sample of about 400 eros with @xmath55 was selected.   the distribution of the eros on the sky is strongly inhomogeneous, being characterized by overdensities and large voids.   we detect at the @xmath6 level a strong clustering signal of the eros which is about an order of magnitude larger than the clustering of @xmath7-selected field galaxies in the same magnitude range. a smooth trend of increasing clustering amplitude with the @xmath8 color is observed.   these results are strong evidence that the largest fraction of eros is composed of high@xmath9 ellipticals, of which we detect for the first time the @xmath10 large scale structure clustering signal.   we show how the surface density variations of the ero population found in our survey can explain the highly discrepant results obtained so far on the density of @xmath11 ellipticals, and we briefly discuss the main implications of our results for the evolution of elliptical galaxies.   the number counts and the colors of the @xmath7-selected field galaxies are also presented and briefly discussed.
this paper considers the quantile regression approach for partially linear spatial autoregressive models with possibly varying coefficients.   b - spline is employed for the approximation of varying coefficients.   the instrumental variable quantile regression approach is employed for parameter estimation.   the rank score tests are developed for hypotheses on the coefficients, including the hypotheses on the non - varying coefficients and the constancy of the varying coefficients.   the asymptotic properties of the proposed estimators and test statistics are both established.   monte carlo simulations are conducted to study the finite sample performance of the proposed method.   analysis of a real data example is presented for illustration. + * keywords * : spatial autoregressive model ; varying coefficient ; partially linear ; quantile regression ; instrumental variables
we present the first part of the first large and homogeneous ccd color - magnitude diagram ( cmd ) data base, comprising 52 nearby galactic globular clusters ( ggc ) imaged in the @xmath0 and @xmath1 bands using only two telescopes ( one for each hemisphere ).   the observed clusters represent @xmath2 of the known galactic globulars with @xmath3  mag, cover most of the globular cluster metallicity range ( @xmath4}\leq -0.4 $ ] ), and span galactocentric distances from @xmath5 to @xmath6 kpc.    in this paper,   the cmds for the 39 ggcs observed in the southern hemisphere are presented.   the remaining 13 northern hemisphere clusters of the catalog are presented in a companion paper. for four clusters ( ngc  4833, ngc  5986, ngc  6543, and ngc  6638 ) we present for the first time a cmd from ccd data. the typical cmd span from the @xmath7 @xmath0 magnitude to the tip of the red giant branch. based on a large number of standard stars,   the absolute photometric calibration is reliable to the @xmath8  mag level in both filters.   this catalog, because of its homogeneity, is expected to represent a useful data base for the measurement of the main absolute and relative parameters characterizing the cmd of ggcs.
it is shown that non - helical ( more precisely, parity - invariant ) flows capable of sustaining a large - scale dynamo by the negative magnetic eddy diffusivity effect are quite common.   this conclusion is based on numerical examination of a large number of randomly selected flows.   few outliers with strongly negative eddy diffusivities are also found, and they are interpreted in terms of the closeness of the control parameter to a critical value for generation of a small - scale magnetic field.   furthermore, it is shown that, for parity - invariant flows, a moderate separation of scales between the basic flow and the magnetic field often significantly reduces the critical magnetic reynolds number for the onset of dynamo action.   eddy diffusivity, kinematic magnetic dynamo, multiscale expansion, instability.   # 1( ) # 1subsection   # 1section   # 1appendix   # 1figure   # 1 # 1 @figuretp # 1 # 2 # 3    ( # 1,#2)(0,0 ) ( 0,0)(#1,#2)#3    7.5 in    v.a. zheligovsky@xmath0, o.m.   podvigina@xmath0, u. frisch@xmath1    @xmath2observatoire de la cte dazur, cnrs umr  6529, + bp  4229, 06304 nice cedex 4, france    @xmath3international institute of earthquake prediction theory + and mathematical geophysics, + 79 bldg.  2, warshavskoe ave., 113556 moscow, russian federation    @
in this note we explain the method how to find the resonance condition on quantum graphs, which is called pseudo orbit expansion. in three examples with standard coupling   we show in detail how to obtain the resonance condition.   we focus on non - weyl graphs, i.e. the graphs which have fewer resonances than expected. for these graphs   we explain benefits of the method of `` deleting edges '' for simplifying the graph.   pacs : 03.65.ge, 03.65.nk, 02.10.ox
we consider two interacting bose - einstein condensates ( bec s ) with different kind of the potential energy of interaction of the condensates : ( a ) the standard potential ; ( b ) the potential has a positive three - body and a negative two - body scattering terms and ( c ) the potential has a positive four - body and a negative three - body scattering terms for the first bec and a positive three - body and a negative two - body scattering terms for the second bec.   it is shown that in these cases there exist regular spherically symmetric solutions.   physically such solution is either a defect or a droplet created by the condensates.   the defect is a cavity filled with one bec on the background of another bec.   the droplet is an object on the background of the empty space. for ( a ) and ( b ) cases the obtained objects are supported by a constant external trapping potential and for ( c ) case   the droplet is a self - maintaining object without any external potential.   the possibility of construction of an elementary logic qubit device on the basis of this droplet is discussed.
magnetic electric effects in ferromagnetic metals are discussed from the viewpoint of effective spin electromagnetic field that couples to conduction electron spin.   the effective field in the adiabatic limit is the spin berry s phase in space and time, and it leads to spin motive force ( voltage generated by magnetization dynamics ) and topological hall effect due to spin chirality. its gauge coupling to spin current describes the spin transfer effect, where magnetization structure is driven by an applied spin current.   the idea of effective gauge field can be extended to include spin relaxation and rashba spin - orbit interaction.   voltage generation by the inverse edelstein effect in junctions is interpreted as due to the electric component of rashba - induced spin gauge field.   the spin gauge field arising from the rashba interaction turns out to coincides with troidal moment, and causes asymmetric light propagation ( directional dichroism ) as a result of the doppler shift.   rashba conductor without magnetization is shown to be natural metamaterial exhibiting negative refraction.
we measure the angular clustering of @xmath0 radio sources in the bootes deep field, covering 5.3  deg@xmath1 down to @xmath2. with reference to work by blake & wall,   we show that the size distribution of multi - component radio galaxies dominates the overall clustering signal, and that its amplitude extrapolates smoothly from their measurements above 5.   the upper limits on any true galaxy - galaxy clustering are consistent with the clustering of sub-  radio - loud agn being effectively diluted by the more weakly - clustered _ iras_-type starburst galaxies.   source count models imply that the survey contains @xmath3 of the latter galaxies above 0.2  out to @xmath4.   measurement of their clustering must await their identification via the optical and infrared data due on this field.    #   1to 0pt#1 # 1 # 1    to size    # 1    to size     = cmr10 scaled2 = cmbx10 scaled2 = cmti10 scaled2 ps.   2    -.65 in    = 6truein    surveys  galaxies : active  galaxies :   starburst  large - scale structure of universe
we discuss how some coronal mass ejections ( cmes ) originating from the western limb of the sun are associated with space weather effects such as solar energetic particles ( seps ), shock or geo - effective ejecta at earth.   we focus on the august 24, 2002 coronal mass ejection, a fast ( @xmath0 2000 km   s@xmath1 ) eruption originating from w81. using a three - dimensional magneto - hydrodynamic simulation of this ejection with the space weather modeling framework ( swmf ),   we show how a realistic initiation mechanism enables us to study the deflection of the cme in the corona and the heliosphere.   reconnection of the erupting magnetic field with that of neighboring streamers and active regions modify the solar connectivity of the field lines connecting to earth and can also partly explain the deflection of the eruption during the first tens of minutes.   comparing the results at 1 au of our simulation with observations by the _ ace _ spacecraft, we find that the simulated shock does not reach earth, but has a maximum angular span of about 120@xmath2, and reaches 35@xmath2 west of earth in 58  hours.   we find no significant deflection of the cme and its associated shock wave in the heliosphere, and we discuss the consequences for the shock angular span.
the comparison studies of theoretical approaches to the description of the casimir interaction in layered systems including graphene is performed.   it is shown that at zero temperature the approach using the polarization tensor leads to the same results as the approach using the longitudinal density - density correlation function of graphene. an explicit expression for the zero - temperature transverse density - density correlation function of graphene   is provided.   we further show that the computational results for the casimir free energy of graphene - graphene and graphene - au plate interactions at room temperature, obtained using the temperature - dependent polarization tensor, deviate significantly from those using the longitudinal density - density correlation function defined at zero temperature.   we derive both the longitudinal and transverse density - density correlation functions of graphene at nonzero temperature.   the casimir free energy in layered structures including graphene, computed using the temperature - dependent correlation functions, is exactly equal to that found using the polarization tensor.
the study of fractional variational problems in terms of a combined fractional caputo derivative is introduced.   necessary optimality conditions of euler  lagrange type for the basic, isoperimetric, and lagrange variational problems are proved, as well as transversality and sufficient optimality conditions.   this allows to obtain necessary and sufficient pareto optimality conditions for multiobjective fractional variational problems.   variational analysis, multiobjective optimization, fractional euler   lagrange equations, fractional derivatives in the sense of caputo, pareto minimizers.    49k05, 26a33.
axioms can be used to model derived predicates in domain- independent planning models. formulating models which use axioms   can sometimes result in problems with much smaller search spaces and shorter plans than the original model.   previous work on axiom - aware planners focused solely on state - space search planners.   we propose axiom - aware planners based on answer set programming and integer programming. we evaluate them on pddl domains with axioms and   show that they can exploit additional expressivity of axioms.
a self - control mechanism for the dynamics of a three - state fully - connected neural network is studied through the introduction of a time - dependent threshold.   the self - adapting threshold is a function of both the neural and the pattern activity in the network.   the time evolution of the order parameters is obtained on the basis of a recently developed dynamical recursive scheme. in the limit of low activity   the mutual information is shown to be the relevant parameter in order to determine the retrieval quality. due to self - control   an improvement of this mutual information content as well as an increase of the storage capacity and an enlargement of the basins of attraction are found.   these results are compared with numerical simulations.   epsf    2
we numerically study the three - dimensional generalization of the kinetically constrained east model, the north - or - east - or - front ( nef ) model.   we characterize the equilibrium behaviour of the nef model in detail, measuring the temperature dependence of several quantities : @xmath0-relaxation time, distributions of relaxation times, dynamic susceptibility, dynamic correlation length, and four - point susceptibility.   we show that the nef model describes quantitatively experimental observations over an exceptionally wide range of timescales.   we illustrate this by fitting experimental data obtained both in the mildly supercooled regime by optical kerr effect, and close to the glass transition by dielectric spectroscopy.
we present colour - magnitude diagrams for two rich ( @xmath010@xmath1m@xmath2 ) large magellanic cloud star clusters with ages @xmath010@xmath3 years, constructed from optical and near - infrared data obtained with the hubble space telescope.   these data are part of an hst project to study lmc clusters with a range of ages. in this paper   we investigate the massive star content of the young clusters, and determine the cluster ages and metallicities, paying particular attention to be star and blue straggler populations and evidence of age spreads.   we compare our data to detailed stellar population simulations to investigate the turn - off structure of @xmath025 myr stellar systems, highlighting the complexity of the blue straggler phenomenon.   globular clusters : individual : ngc 1805, globular clusters : individual : ngc 1818, globular clusters : general, galaxies : individual : large magellanic cloud, blue stragglers, stars : emission - line, be
we studied the pressure dependence of the room - temperature infrared reflectivity of @xmath0  along all three optical axes.   this anisotropic organic compound consists of molecular stacks with orbital overlap along the @xmath1 direction ; due to electronic correlations the system is a quasi - one - dimensional mott insulator with a charge gap @xmath2  mev.   the gap is gradually reduced with increasing external pressure, accompanied by the onset of a drude contribution along the stacking direction. in the perpendicular @xmath3 direction a drude - like optical response is observed for pressures above 2  gpa.   this behavior is interpreted in terms of a deconfinement of the electrons in a one - dimensional mott insulator, i.e.  an insulator - to - metal transition which occurs when the interchain transfer integral @xmath4 is approximately equal to half of the charge gap energy.   we estimate the values of @xmath4 and the luttinger liquid parameter @xmath5 as a function of pressure.
this review summarizes the state of the art in searches for supersymmetry at colliders on the eve of the lhc era.   supersymmetry is unique among extensions of the standard model in being motivated by naturalness, dark matter, and force unification, both with and without gravity. at the same time  , weak - scale supersymmetry encompasses a wide range of experimental signals that are also found in many other frameworks.   we recall the motivations for supersymmetry and review the various models and their distinctive features.   we then comprehensively summarize searches for neutral and charged higgs bosons and standard model superpartners at the high energy frontier, considering both canonical and non - canonical supersymmetric models, and including results from lep, hera, and the tevatron.
we consider two dimensional non linear sigma models on few symmetric superspaces, which are supergroup manifolds of coset type.   for those spaces where one loop beta function vanishes, two loop beta function is calculated and is shown to be zero.   vanishing of beta function in all orders of perturbation theory is shown for the principal chiral models on group supermanifolds with zero killing form.   sigma models on symmetric ( super ) spaces on supergroup manifold @xmath0 are known to be classically integrable.   we investigate a possibility to extend an argument of absence of quantum anomalies in non local current conservation from non super case to the case of supergroup manifolds which are asymptotically free in one loop.
results of a 1997 september 910 bepposax observation of the 5.57  hr low - mass x - ray binary ( lmxrb )  are presented.   the 0.340  kev spectrum is unusually complex and can not be fit by any of the standard models applied to other lmxrb.   at least two components are required.   one component has a shape consistent with that expected from the comptonization of an input soft ( wien ) spectrum while the other, contributing @xmath040% of the 110  kev flux, is consistent with being a blackbody. in addition  , there is a `` dip '' in the spectrum which can be modeled by a @xmath1  kev absorption edge with an optical depth, @xmath2, of @xmath3. if the same model is fit to asca solid - state imaging spectrometer spectra obtained in 1993 and 1996, then reasonable fits are also obtained, with a similar absorption feature required.   the nature of this feature is highly uncertain ; its energy corresponds to the k - edges of highly ionized ne  x and neutral mg, or to an l - edge of moderately ionized fe.   surprisingly, no strong ( @xmath4 ) fe - k or ( @xmath5 ) o - k edges are visible.   the folded lightcurve of  is similar to previous observations, except that no strong softening is seen near the eclipse.   an updated orbital ephemeris is provided.
we have developed a procedure for the classification of eclipsing binaries from their light - curve parameters and spectral type.   the procedure was tested on more than 1000 systems with known classification, and its efficiency was estimated for every evolutionary status we use.   the procedure was applied to about 4700 binaries with no classification, and the vast majority of them was classified successfully.   systems of relatively rare evolutionary classes were detected in that process, as well as systems with unusual and/or contradictory parameters. also, for 50 previously unclassified cluster binaries evolutionary classes were identified.   these stars can serve as tracers for age and distance estimation of their parent stellar systems.   the procedure proved itself as fast, flexible and effective enough to be applied to large ground based and space born surveys, containing tens of thousands of eclipsing binaries.       binaries : eclipsing  stars : evolution
recent theoretical predictions and experimental measurements have demonstrated that equilibrium free energy differences can be obtained from exponential averages of nonequilibrium work values.   these results are similar in structure, but not equivalent, to predictions derived nearly three decades ago by bochkov and kuzovlev, which are also formulated in terms of exponential averages but do not involve free energy differences. in the present paper the relationship between these two sets of results is elucidated, then illustrated with an undergraduate - level solvable model.   the analysis also serves to clarify the physical interpretation of different definitions of work that have been used in the context of thermodynamic systems driven away from equilibrium.
density functional calculations were performed to systematically study a series of finite and infinite cluster - assembled silicon nanotubes ( sints ).   one - dimensional sints can be prepared by proper assembly of hydrogenated cage - like silicon clusters to form semiconductors with a large band gap, and their electronic properties can be accurately tuned by transition metal doping in the center of the tubes. specifically, doping with fe made the sints metallic and magnetic materials.   more interestingly, a metal to half - metal transition was observed with increasing tube radius in fe - doped sints, which demonstrates that sints doped with magnetic elements may find important applications in spintronics.   keywords : hydrogenated silicon clusters, homo - lumo gap order, cluster - assembled nanotube, magnetic properties, metal half - metal transition
the issue of a starburst - agn connection in local and distant galaxies is relevant for understanding galaxy formation and evolution, the star formation and metal enrichment history of the universe, the origin of the extragalactic background at low and high energies, and the origin of nuclear activity in galaxies. here   i review some of the observational evidence recently brought forward in favor of a connection between the starburst and agn phenomena.   i conclude by raising a number of questions concerning the exact nature of this connection.
it is straightforward to determine the size of the earth and the distance to the moon without making use of a telescope.   the methods have been known since the 3rd century bc.   however, few amateur or professional astronomers have worked this out from data they themselves have taken.   here we use a _ gnomon _ to determine the latitude and longitude of south bend, indiana, and college station, texas, and determine a value of the radius of the earth of 6290 km, only 1.4 percent smaller than the true value.   we use the method of aristarchus and the size of the earth s shadow during the lunar eclipse of 2011 june 15 to derive an estimate of the distance to the moon ( 62.3 r@xmath0 ), some 3.3 percent greater than the true mean value.   we use measurements of the angular motion of the moon against the background stars over the course of two nights, using a simple cross staff device, to estimate the moon s distance at perigee and apogee.   finally, we use simultaneous ccd observations of asteroid 1996 hw1 obtained with small telescopes in socorro, new mexico, and ojai, california, to derive a value of the astronomical unit of ( 1.59 @xmath1 0.19 ) @xmath2 10@xmath3 km, about 6 percent too large.   the data and methods presented here can easily become part of a beginning astronomy lab class.
when a shallow layer of inviscid fluid flows over a substrate, the fluid particle trajectories are, to leading order in the layer thickness, geodesics on the two - dimensional curved space of the substrate. since the two - dimensional geodesic equation is a two degree - of - freedom autonomous hamiltonian system, it can exhibit chaos, depending on the shape of the substrate.   we find chaotic behaviour for a range of substrates.
we present the observed pulsation spectra of all known non - interacting zz  ceti stars ( hydrogen atmosphere white dwarf variables ; davs ) and examine changes in their pulsation properties across the instability strip.   we confirm the well established trend of increasing pulsation period with decreasing effective temperature across the zz  ceti instability strip.   we do not find a dramatic order of magnitude increase in the number of observed independent modes in zz  ceti stars, traversing from the hot to the cool edge of the instability strip ; we find that the cool davs have one more mode on average compared to the hot davs.   we confirm the initial increase in pulsation amplitude at the blue edge, and find strong evidence of a decline in amplitude prior to the red edge.   we present the first observational evidence that zz  ceti stars lose pulsation energy just before pulsations shut down at the empirical red edge of the instability strip.
_ counterfactual regret minimization _ ( cfr ) is the most popular iterative algorithm for solving zero - sum imperfect - information games. _   regret - based pruning _ ( rbp ) is an improvement that allows poorly - performing actions to be temporarily pruned, thus speeding up cfr.   we introduce _ total rbp _, a new form of rbp that reduces the space requirements of cfr as actions are pruned.   we prove that in zero - sum games it asymptotically prunes any action that is not part of a best response to some nash equilibrium.   this leads to provably faster convergence and lower space requirements.   experiments show that total rbp results in an order of magnitude reduction in space, and the reduction factor increases with game size.
neutrinos are allowed to mix and to oscillate among their flavor.   muon and tau in particular oscillate at largest values.   last minos experiment claimed @xcite possible difference among their matter and anti - matter masses, leading to a first violation of the most believed cpt symmetry.   isotropically born atmospheric muon neutrino at @xmath0 gev, while up - going, they might be partially suppressed by mixing in analogy to historical superkamiokande muon neutrino disappearance into tau, leading to large scale anisotropy signals. here   we show an independent muon rate foreseen in deep core based on observed sk signals extrapolated to deepcore mass and its surrounding.   our rate prediction partially differ from previous ones.   the @xmath1, @xmath2 disappearance into @xmath3,@xmath4 is leading to a @xmath5, @xmath6 anisotropy in vertical up - going muon track : in particular along channel @xmath7 we expect a huge rate ( tens of thousand of events ) of neutral current events, charged current electron and inclined crossing muons.   moreover at channel @xmath8 we expect a severe suppression of the rate due to muon disappearance ( in cpt conserved frame ).   such an anisotropy might be partially tested by two - three string detection at @xmath9.   a cpt violation may induce a more remarkable suppression of vertical up - going tracks because of larger @xmath2 reduction for @xmath10.
the absorption spectrum of the title compound in the spectral range of the hydrogen - bonded oh - stretching vibration has been investigated using a five - dimensional gas phase model as well as a qm / mm classical molecular dynamics simulation in solution.   the gas phase model predicts a fermi - resonance between the oh - stretching fundamental and the first oh - bending overtone transition with considerable oscillator strength redistribution. the anharmonic coupling to a low - frequency vibration of the hydrogen bond leading to a vibrational progression is studied within a diabatic potential energy curve model.   the condensed phase simulation of the dipole - dipole correlation function results in a broad band in the 3000 region in good agreement with experimental data.   further, weaker absorption features around 2600 have been identified as being due to motion of the hydrogen within the hydrogen bond.   vibrational dynamics, hydrogen bonds, infrared spectroscopy, cpmd simulations
gamma - rays provide a powerful insight into the non - thermal universe and perhaps a unique probe for new physics beyond the standard model.   current experiments are already giving results in the physics of acceleration of cosmic rays in supernova remnants, pulsar and active galactic nuclei with a hundred sources detected at very - high - energies so far. despite its relatively recent appearance,   very high - energy gamma - ray astronomy has proven to have reached a mature technology with fast assembling, relatively cheap and reliable telescopes.   the goal of future installation is to increase the sensitivity by a factor ten compared to current installations, and enlarge the energy domain from few tens of gev to a hundred tev.   gamma - ray spectra of astrophysical origin are rather soft thus hardly one single size telescope can cover more than 1.5 decades in energy, therefore an array of telescopes of @xmath0 different sizes is required.   hereafter, we present design considerations for a cherenkov telescope array ( cta ), a project for a new generation of highly automated telescopes for gamma - ray astronomy.   the status of the project, technical solutions and an insight in the involved physics will be presented.
3.0 ex we study the factorization of the dijet cross section in @xmath0 annihilation using the generalized exclusive jet algorithm which includes the cone - type, the jade, the @xmath1, the anti-@xmath1 and the cambridge / aachen jet algorithms as special cases. in order to probe the characteristics of the jet algorithms in a unified way  , we consider the generalized @xmath1 jet algorithm with an arbitrary weight of the energies, in which various types of the @xmath1-type algorithms are included for specific values of the parameter.   we show that the jet algorithm respects the factorization property for the parameter @xmath2. the factorized jet function and the soft function   are well defined and infrared safe for all the jet algorithms except the @xmath1 algorithm.   the @xmath1 algorithm ( @xmath3 ) breaks the factorization since the jet and the soft functions are infrared divergent and are not defined for @xmath3, though the dijet cross section is infrared finite. in the jet algorithms which enable factorization,   we give a phenomenological analysis using the resummed and the fixed - order results.    3.0 ex
the neutrinos detected from the next galactic core - collapse supernova will contain valuable information on the internal dynamics of the explosion.   one mechanism leading to a temporal evolution of the neutrino signal is the variation of the induced neutrino flavor mixing driven by changes in the density profile. with one and two dimensional hydrodynamical simulations we identify the behavior and properties of prominent features of the explosion.   using these results we demonstrate the time variation of the neutrino crossing probabilities due to changes in the msw neutrino transformations as the star explodes by using the s - matrix - monte carlo - approach to neutrino propagation. after adopting spectra for the neutrinos emitted from the proto - neutron star we calculate for a galactic supernova   the evolution of the positron spectra within a water cerenkov detector and the ratio of charged current to neutral current event rates for a heavy water - sno like - detector and find that these detector signals are feasible probes of a number of explosion features.
a model for synchronization of globally coupled phase oscillators including `` inertial '' effects is analyzed.   in such a model, both oscillator frequencies and phases evolve in time.   stationary solutions include incoherent ( unsynchronized ) and synchronized states of the oscillator population. assuming a lorentzian distribution of oscillator natural frequencies, @xmath0, both larger inertia or larger frequency spread stabilize the incoherent solution, thereby making harder to synchronize the population. in the limiting case @xmath1, the critical coupling becomes independent of inertia.   a richer phenomenology is found for bimodal distributions.   for instance, inertial effects may destabilize incoherence, giving rise to bifurcating synchronized standing wave states.   inertia tends to harden the bifurcation from incoherence to synchronized states : at zero inertia, this bifurcation is supercritical ( soft ), but it tends to become subcritical ( hard ) as inertia increases.   nonlinear stability is investigated in the limit of high natural frequencies.
some dynamical properties of a bouncing ball model under the presence of an external force modeled by two nonlinear terms are studied.   the description of the model is made by use of a two dimensional nonlinear measure preserving map on the variables velocity of the particle and time.   we show that raising the straight of a control parameter which controls one of the nonlinearities, the positive lyapunov exponent decreases in the average and suffers abrupt changes.   we also show that for a specific range of control parameters, the model exhibits the phenomenon of fermi acceleration.   the explanation of both behaviours is given in terms of the shape of the external force and due to a discontinuity of the moving wall s velocity.
strangeness flavor yield @xmath0 and the entropy yield @xmath1 are the observables of the deconfined quark - gluon state of matter which can be studied in the entire available experimental energy range at ags, sps, rhic, and, in near future, at the lhc energy range.   we present here a comprehensive analysis of strange, soft hadron production as function of energy and reaction volume.   we discuss the physical properties of the final state and argue how evidence about the primordial qgp emerges.   .   -12.cm _   5th international conference on physics and astrophysics of quark gluon plasma, _   + february 8 - 12, 2005, salt lake city, kolkata, india, + _ journal of physics : conference series _ 11.cm
we present a spectroscopic survey of almost 15,000 candidate intermediate - redshift luminous red galaxies ( lrgs ) brighter than @xmath0, observed with 2df on the anglo - australian telescope.   the targets were selected photometrically from the sloan digital sky survey ( sdss ) and lie along two narrow equatorial strips covering 180  @xmath1.   reliable redshifts were obtained for 92% of the targets and the selection is very efficient : over 90% have @xmath2.   more than 80% of the @xmath3 red galaxies have pure absorption - line spectra consistent with a passively - evolving old stellar population.   the redshift, photometric and spatial distributions of the lrgs are described.   the 2slaq data will be released publicly from mid-2006, providing a powerful resource for observational cosmology and the study of galaxy evolution.       galaxies : high redshift  cosmology : observations  surveys  catalogues
we explore a consistent way to extend the partially conserved axial vector current ( pcac ) relationship and corresponding current algebra results in two strongly correlated directions : 1 ) towards a search for a set of systematic rules for the establishment of pcac related relationships in a finite low momentum transfer region and for the extrapolation of the momentum transfer @xmath0 to zero when deriving the low energy pcac results that can be compared to experimental data and 2 ) towards taking into account, besides the conventional one, the only other possibility of the spontaneous chiral symmetry breaking, @xmath1, inside a baryonic system by a condensation ( in the sense to be specified in the paper ) of diquarks.   the paper includes investigations of a chiral ward   takahashi identity, the explicit chiral symmetry breaking by a finite current quark mass, the modification of the pcac relationship and its consequences.   it is shown that the signals for a hypothetical diquark condensation inside a nucleon and nucleus is observable in high precision experiments despite the fact that they may evade most of the current observations.   we briefly discuss how diquark condensation could provide an answer to the question of where about of pions and quark number in a nucleon and a nucleus, which is raised in explaining puzzles in polarized pion nucleus scattering, violation of gottfried sum rule and emc effects.
in this paper we elaborate on the structure of the semigroup tree and the regularities on the number of descendants of each node observed in @xcite.   these regularites admit two different types of behavior and in this work we investigate which of the two types takes place in particular for well - known classes of semigroups.   also we study the question of what kind of chains appear in the tree and characterize the properties ( like being ( in)finite ) thereof.   we conclude with some thoughts that show how this study of the semigroup tree may help in solving the conjecture of fibonacci - like behavior of the number of semigroups with given genus.   * keywords * : numerical semigroup, fibonacci numbers.
we present the discovery of eight quasars at @xmath0 identified in the sloan digital sky survey ( sdss ) overlap regions.   individual sdss imaging runs have some overlap with each other, leading to repeat observations over an area spanning @xmath14000 deg@xmath2 ( more than 1/4 of the total footprint ).   these overlap regions provide a unique dataset that allows us to select high - redshift quasars more than 0.5 mag fainter in the @xmath3 band than those found with the sdss single - epoch data.   our quasar candidates were first selected as @xmath4-band dropout objects in the sdss imaging database.   we then carried out a series of follow - up observations in the optical and near - ir to improve photometry, remove contaminants, and identify quasars.   the eight quasars reported here were discovered in a pilot study utilizing the overlap regions at high galactic latitude ( @xmath5 deg ).   these quasars span a redshift range of @xmath6 and a flux range of @xmath7 mag.   five of them are fainter than @xmath8 mag, the typical magnitude limit of @xmath0 quasars used for the sdss single - epoch images.   in addition, we recover eight previously known quasars at @xmath0 that are located in the overlap regions.   these results validate our procedure for selecting quasar candidates from the overlap regions and confirming them with follow - up observations, and provide guidance to a future systematic survey over all sdss imaging regions with repeat observations.
muse, a 2nd generation vlt instrument, will become the world s largest integral field spectrograph  . it will be an ao assisted instrument which, in a single exposure, covers the wavelength range from 465 to 930 nm with an average resolution of 3000 over a field of view of 1@xmath01 with 0.2  spatial sampling.   both the complexity and the rate of the data are a challenge for the data processing of this instrument.   + we will give an overview of the data processing scheme that has been designed for muse.   specifically, we will use only a single resampling step from the raw data to the reduced data product.   this allows us to improve data quality, accurately propagate variance, and minimize spreading of artifacts and correlated noise.   this approach necessitates changes to the standard way in which reduction steps like wavelength calibration and sky subtraction are carried out, but can be expanded to include combination of multiple exposures.
we employ a semi - classical langevin approach to study current - induced atomic dynamics in a partially dehydrogenated armchair graphene nanoribbon.   all parameters are obtained from density functional theory.   the dehydrogenated carbon dimers behave as effective impurities, whose motion decouples from the rest of carbon atoms.   the electrical current can couple the dimer motion in a coherent fashion.   the coupling, which is mediated by nonconservative and pseudo - magnetic current - induced forces, change the atomic dynamics, and thereby show their signature in this simple system.   we study the atomic dynamics and current - induced vibrational instabilities using a simplified eigen - mode analysis.   our study shows that the armchair nanoribbon serves as a possible testbed for probing the current - induced forces.
we have discovered 20 dwarf cepheids ( dc ) in the carina dsph galaxy from the analysis of individual ccd images obtained for a deep photometric study of the system.   these short - period pulsating variable stars are by far the most distant ( @xmath0100 kpc ) and faintest ( @xmath1 ) dcs known.   the carina dcs obey a well - defined period - luminosity relation, allowing us to readily distinguish between overtone and fundamental pulsators in nearly every case.   unlike rr  lyr stars, the pulsation mode turns out to be uncorrelated with light - curve shape, nor do the overtone pulsators tend towards shorter periods compared to the fundamental pulsators. using the period - luminosity ( pl ) relations from nemec et al.   ( 1994 aj, 108, 222 ) and mcnamara ( 1995, aj, 109, 1751 ), we derive @xmath2, for e@xmath3 = 0.025 and  = @xmath42.0, in good agreement with recent, independent estimates of the distance / reddening of carina.   the error reflects the uncertainties in the dc distance scale, and in the metallicity and reddening of carina.   the frequency of dcs among upper main sequence stars in carina is approximately 3%.   the ratio of dwarf cepheids to rr  lyr stars in carina is 0.13 @xmath5 0.10, though this result is highly sensitive to the star - formation history of carina and the evolution of the horizontal branch.   we discuss how dcs may be useful to search effectively for substructure in the galactic halo out to galactocentric distances of @xmath6 kpc.
we prove that under semismall smooth flops, smooth projective varieties have ( non - canonically ) isomorphic chow motives with coefficients in any noetherian local ring @xmath0 by comparing the pushforward of the constant intersection complexes through flopping contractions.   nous montrons que les varits projectives lisses ont les motifs de chow  coefficient dans un anneau local nthrien non - canoniquement isomorphes sous flops semi - petits par comparer les images directes des complexes dintersection constants par contractions crpantes.
we present a solution of the problem of the optimal unambiguous comparison of two ensembles of unknown quantum states @xmath0 and @xmath1.   we consider two cases : 1 ) the two unknown states @xmath2 and @xmath3 are arbitrary states of qudits.   2 ) alternatively, they are coherent states of a harmonic oscillator. for the case of coherent states   we propose a simple experimental realization of the optimal `` comparison '' machine composed of a finite number of beam - splitters and a single photodetector.
-.3 true in this paper uses the caustic crossing events in the microlens data sets to explore the nature and location of the lenses.   we conclude that the large majority of lenses, whether they are luminous or dark, are likely to be binaries.   further, we demonstrate that blending is an important feature of all the data sets.   an additional interpretation suggested by the data, that the caustic crossing events along the directions to the magellanic clouds are due to lenses located in the clouds, implies that most of the lmc / smc events to date are due to lenses in the magellanic clouds.   all of these conclusions can be tested.   if they are correct, a large fraction of lenses along the direction to the lmc may be ordinary stellar binary systems, just as are the majority of the lenses along the direction to the bulge.   thus, a better understanding of the larger - than - anticipated value derived for the bulge optical depth may allow us to better interpret the large value derived for the optical depth to the lmc.   indeed, binarity and blending in the data sets may illuminate connections among several other puzzles : the dearth of binary - source s, the dearth of non - caustic - crossing perturbed binary - lens s, and the dearth of obviously blended point - lens s.    # 1(#1 )    -.8 true in    -0.4 true in -0.3 true in
we introduce a new class of models describing the quark mass hierarchy. in this class,   the dynamics primarily responsible for electroweak symmetry breaking ( ewsb ) leads to the mass spectrum of quarks with no ( or weak ) isospin violation.   moreover, the values of these masses are of the order of the observed masses of the down - type quarks. then, strong ( although subcritical ) horizontal diagonal interactions for the @xmath0 quark plus horizontal flavor - changing neutral interactions between different families lead ( with no fine tuning ) to a realistic quark mass spectrum. in this scenario, many composite higgs bosons occur. a concrete model with the dynamical ewsb with the fourth family is described in detail.
using the combined capabilities of the large near - infrared palomar / deep-2 survey, and the superb resolution of the acs hst camera, we explore the size evolution of 831 very massive galaxies ( m@xmath0@xmath110@xmath2h@xmath3@xmath4m@xmath5 ) since z@xmath62.   we split our sample according to their light concentration using the srsic index @xmath7. at a given stellar mass,   both low ( n@xmath82.5 ) and high ( n@xmath92.5 ) concentrated objects were much smaller in the past than their local massive counterparts.   this evolution is particularly strong for the highly concentrated ( spheroid - like ) objects. at z@xmath61.5,   massive spheroid - like objects were a factor of 4(@xmath100.4 ) smaller ( i.e. almost two orders of magnitudes denser ) than those we see today.   these small sized, high mass galaxies do not exist in the nearby universe, suggesting that this population merged with other galaxies over several billion years to form the largest galaxies we see today.       galaxies : evolution ; galaxies : elliptical and lenticular, cd ; galaxies : formation ; galaxies : fundamental parameters ; galaxies : high redshift ; galaxies : structure
in this paper, we introduce the counterterms that remove the non - logarithmic divergences of the action in third order lovelock gravity for static spacetimes.   we do this by defining the cosmological constant in such a way that the asymptotic form of the metric have the same form in lovelock and einstein gravities.   thus, we employ the counterterms of einstein gravity and show that the power law divergences of the action of lovelock gravity for static spacetimes can be removed by suitable choice of coefficients.   we find that the dependence of these coefficients on the dimension in lovelock gravity is the same as in einstein gravity.   we also introduce the finite energy - momentum tensor and employ these counterterms to calculate the finite action and mass of static black hole solutions of third order lovelock gravity.   next, we calculate the thermodynamic quantities and show that the entropy calculated through the use of gibbs - duhem relation is consistent with the obtained entropy by wald s formula.   furthermore, we find that in contrast to einstein gravity in which there exists no uncharged extreme black hole, third order lovelock gravity can have these kind of black holes.   finally, we investigate the stability of static charged black holes of lovelock gravity in canonical ensemble and find that small black holes show a phase transition between very small and small black holes, while the large ones are stable.
recent experimental advances in using strain engineering to significantly alter the band structure of moderately correlated systems offer opportunities and challenges to weak - coupling renormalization group ( rg ) analysis approaches for predicting superconducting instabilities. on one hand  , the rg approach can provide theoretical guidance. on the other hand, it is now imperative to better understand how the predictions of the rg approach depends on microscopic and non - universal model details.   here we focus on the effect of band - selective mass - renormalization often observed in angle resolved photoemission spectroscopy.   focusing on a specific example of uniaxially strained @xmath0 we carry out the weak - coupling rg analysis from two sets of band structures as starting points : one is based on density functional theory ( dft ) calculations and the other is based on angle - resolved photoemission spectroscopy ( arpes ) measurements. despite good agreement between the fermi surfaces of the the two band structures we find the two sets of band structures to predict qualitatively different trends in the strain dependence of the superconducting transition temperature @xmath1 as well as the dominant channel.
we present the first results of a study of faint 12@xmath0 m sources detected with the infrared space observatory ( iso ) in four deep, high galactic latitude fields.   the sample includes 50 such sources in an area of 0.1 square degrees down to a 5@xmath1 flux limit of @xmath2jy. from optical identifications based on the us naval observatory ( usno ) catalogue and analysis of the optical / ir colours and digital sky survey ( dss ) images,   we conclude that 37 of these objects are galaxies and 13 are stars. we derive galaxy number counts and compare them with existing iras counts at 12@xmath0 m, and with models of the 12@xmath0 m source population.   in particular, we find evidence for significant evolution in the galaxy population, with the no - evolution case excluded at the 3.5@xmath1 level.   the stellar population is well matched by existing models.   two of the objects detected at 12@xmath0 m are associated with known galaxies.   one of these is an iras galaxy at z=0.11 with a luminosity of 10@xmath3.
we present a computational scheme for extracting the energy level alignment of a metal / molecule interface, based on constrained density functional theory and local exchange and correlation functionals.   the method, applied here to benzene on li(100 ), allows us to evaluate charge transfer energies, as well as the spatial distribution of the image charge induced on the metal surface.   we systematically study the energies for charge transfer from the molecule to the substrate as function of the molecule - substrate distance, and investigate the effects arising from image charge confinement and local charge neutrality violation. for benzene on li(100 ) we find that the image charge plane is located at about 1.8    above the li surface, and that our calculated charge transfer energies compare perfectly with those obtained with a classical electrostatic model having the image plane located at the same position.   the methodology outlined here can be applied to study any metal / organic interface in the weak coupling limit at the computational cost of a total energy calculation.   most importantly, as the scheme is based on total energies and not on correcting the kohn - sham quasi - particle spectrum, accurate results can be obtained with local / semi - local exchange and correlation functionals.   this enables a systematic approach to convergence.
we give a mathematical framework for weighted ensemble ( we ) sampling, a binning and resampling technique for efficiently computing probabilities in molecular dynamics.   we prove that we sampling is unbiased in a very general setting that includes adaptive binning.   we show that when we is used for stationary calculations in tandem with a markov state model ( msm ), the msm can be used to optimize the allocation of replicas in the bins.   molecular dynamics, markov chains, stationary distributions, long time dynamics, coarse graining, resampling, weighted ensemble    65c05, 65c20, 65c40, 65y05, 82c80
we provide the solution of the classical theory for the higgs sector of the standard model obtaining the exact green function for the broken phase. solving the dyson - schwinger equations for the higgs field   we show that the propagator coincides with that of the classical theory confirming the spectrum also at the quantum level. in this way   we obtain a proof of triviality using the kllen - lehman representation.   this has as a consequence that higher excited states must exist for the higgs particle, representing an internal spectrum for it.   higher excited states have exponentially smaller amplitudes and so, their production rates are significantly depressed.
we propose a moving mesh adaptive approach for solving time - dependent partial differential equations.   the motion of spatial grid points is governed by a moving mesh pde ( mmpde ) in which a _ mesh relaxation time _ @xmath0 is employed as a regularization parameter. previously reported results on mmpdes have invariably employed a constant value of the parameter @xmath0.   we extend this standard approach by incorporating a variable relaxation time that is calculated adaptively alongside the solution in order to regularize the mesh appropriately throughout a computation.   we focus on singular problems involving self - similar blow - up to demonstrate the advantages of using a variable relaxation time over a fixed one in terms of accuracy, stability and efficiency.   _ ams classification : _   65m50, 65m06, 35k57    and    moving mesh method ; self - similar blow - up ; relaxation time
we present a set of cluster models that link the present - day properties of clusters to the processes that govern galaxy formation.   these models treat the entropy distribution of the intracluster medium as its most fundamental property. because convection strives to establish an entropy gradient that rises with radius, the observable properties of a relaxed cluster depend entirely on its dark - matter potential and the entropy distribution of its uncondensed gas.   guided by simulations, we compute the intracluster entropy distribution that arises in the absence of radiative cooling and supernova heating by assuming that the gas - density distribution would be identical to that of the dark matter.   the lowest - entropy gas would then fall below a critical entropy threshold at which the cooling time equals a hubble time.   radiative cooling and whatever feedback is associated with it must modify the entropy of that low - entropy gas, changing the overall entropy distribution function and thereby altering the observable properties of the cluster. using some phenomenological prescriptions for entropy modification based on the existence of this cooling threshold, we construct a remarkably realistic set of cluster models.   the surface - brightness profiles, mass - temperature relation, and luminosity - temperature relation of observed clusters all naturally emerge from these models. by introducing a single adjustable parameter related to the amount of intracluster gas that can cool within a hubble time  , we can also reproduce the observed temperature gradients of clusters and the deviations of cooling - flow clusters from the standard luminosity - temperature relation.
the potentials between static sources in various representations in @xmath0 are calculated based on the fat - center - vortices model of faber, greensite and olejnk. at intermediate distances,   most distributions of the flux within vortices lead to potentials that are qualitatively in agreement with `` casimir scaling, '' which says that the string tension is proportional to the quadratic operator of the representation.   however, at the quantitative level, violations of casimir scaling are generally much larger than those seen in numerical simulations, indicating that additional physical input to the fat - center - vortices model is required. at large distances  , screening occurs for zero - triality representations ; for the representations with non - zero triality the string tension equals that of the fundamental representation.   some rather `` unphysical '' flux distributions can lead to violations of casimir scaling at intermediate distances and violations of the expected ordering of representations at large distances.    #
we discuss the scenario of light neutralino dark matter in the minimal supersymmetric standard model, which is motivated by the results of some of the direct detection experiments  dama / libra, cogent, and cresst.   we update our previous analysis with the latest results of the lhc.   we show that new lhc constraints disfavour the parameter region that can reproduce the results of dama / libra and cogent.   mpp-2011 - 144
we present the results of a strong - lensing analysis of a complete sample of 12 very luminous x - ray clusters at @xmath0 using hst / acs images.   our modelling technique has uncovered some of the largest known critical curves outlined by many accurately - predicted sets of multiple images.   the distribution of einstein radii has a median value of @xmath1 ( for a source redshift of @xmath2 ), twice as large as other lower-@xmath3 samples, and extends to @xmath4 for macs j0717.5 + 3745, with an impressive enclosed einstein mass of @xmath5.   we find that 9 clusters cover a very large area ( @xmath6 ) of high magnification ( @xmath7 ) for a source redshift of @xmath8, providing primary targets for accessing the first stars and galaxies.   we compare our results with theoretical predictions of the standard @xmath9cdm model which we show systematically fall short of our measured einstein radii by a factor of @xmath10, after accounting for the effect of lensing projection. nevertheless, a revised analysis once arc redshifts become available, and similar analyses of larger samples, are needed in order to establish more precisely the level of discrepancy with @xmath9cdm predictions.       dark matter, galaxies : clusters : individuals : macs @xmath0 sample, galaxies : clusters : general, gravitational lensing
starting from the second law of thermodynamics applied to an isolated system consisting of the system surrounded by an extremely large medium, we formulate a general non - equilibrium thermodynamic description of the system when it is out of equilibrium.   we then apply it to study the structural relaxation in glasses and establish the phenomenology behind the concept of the fictive temperature and of the empirical tool - narayanaswamy equation on firmer theoretical foundation.
we present diffusion monte carlo calculations of d@xmath0 adsorbed inside a narrow carbon nanotube.   the 1d d@xmath0 equation of state is reported, and the one - dimensional character of the adsorbed d@xmath0 is analyzed.   the isotopic dependence of the constitutive properties of the quantum fluid are studied by comparing d@xmath0 and h@xmath0.   quantum effects due to their different masses are observed both in the energetic and the structural properties.   the influence of the interatomic potential in one - dimensional systems is also studied by comparing the properties of d@xmath0 and @xmath1he which have nearly the same mass but a sizeably different potential.   the physics of molecular hydrogen adsorbed in the interstitial channels of a bundle of nanotubes is analyzed by means of both a diffusion monte carlo calculation and an approximate mean field method.
in practical ultra - wideband ( uwb ) systems, rake receivers are not able to fully take advantage of all resolvable paths, because of the required computational and power resources. on the other hand,   transmitted reference ( tr ) schemes are simple, robust structures with low power consumption and they do not require channel estimation, but they sustain a 3db energy / rate loss, as each symbol requires the transmission of two pulses. alternatively, the differential tr ( dtr ) scheme offers 3db performance gain compared to conventional tr structures and double data rates since the previously transmitted data pulse is used as a reference. in this paper   we introduce a less complex, energy - efficient tr scheme, called self reference ( sr ) uwb system, which uses as reference an elaborated replica of the received signal.   it is shown that the sr scheme outperforms the dtr one in terms of error performance and achieves double data - rate compared to conventional tr schemes.   differential transmitted reference uwb, fading channel, self reference uwb, transmitted reference uwb, uwb.
we study the 37 brightest radio sources in the subaru/_xmm - newton _ deep field ( sxdf ). using mid - ir ( spitzer mips 24 @xmath0 ) data we expect to trace nuclear accretion activity, even if it is obscured at optical wavelengths, unless the obscuring column is extreme.   our results suggest that above the ` fri / frii'radio luminosity break most of the radio sources are associated with objects that have excess mid - ir emission, only some of which are broad - line objects, although there is one clear low - accretion - rate fri.   the fraction of objects with mid - ir excess drops dramatically below the fri / frii break, although there exists at least one high - accretion - rate qso.   investigation of mid - ir and blue excesses shows that they are correlated as predicted by a model in which a torus of dust absorbs @xmath130% of the light, and the dust above and below the torus scatters @xmath21% of the light.   
various novel transport phenomena in chiral systems result from the interplay of quantum anomalies with magnetic field and vorticity in high - energy heavy - ion collisions, and could survive the expansion of the fireball and be detected in experiments. among them are the chiral magnetic effect, the chiral vortical effect and the chiral magnetic wave, the experimental searches for which have aroused extensive interest.   the goal of this review is to describe the current status of experimental studies at relativistic heavy ion collider at bnl and the large hadron collider at cern, and to outline the future work in experiment needed to eliminate the existing uncertainties in the interpretation of the data.
a significant fraction ( @xmath030% ) of the high - energy gamma - ray sources listed in the second _ fermi _  lat catalog ( 2fgl ) are still of unknown origin, being not yet associated with counterparts at low energies.   we recently developed a new association method to identify if there is a @xmath1-ray blazar candidate within the positional uncertainty region of a generic 2fgl source.   this method is entirely based on the discovery that blazars have distinct infrared colors with respect to other extragalactic sources found thanks, to the wide - field infrared survey explorer ( _ wise _ ) all - sky observations.   several improvements have been also performed to increase the efficiency of our method in recognizing @xmath1-ray blazar candidates. in this paper   we applied our method to two different samples, the first constituted by the unidentified @xmath1-ray sources ( ugss ) while the second by the active galaxies of uncertain type ( agus ), both listed in the 2fgl.   we present a catalog of ir counterparts for @xmath020% of the ugss investigated.   then, we also compare our results on the associated sources with those present in literature.   in addition, we illustrate the extensive archival research carried out to identify the radio, infrared, optical and x - ray counterparts of the _ wise _  selected, @xmath1-ray blazar candidates.   finally, we discuss the future developments of our method based on ground - based follow - up observations.
we examine particle entanglement, characterized by pseudo - spin squeezing, of spin-1 bosonic atoms with coupled ground states in a one - dimensional optical lattice.   both the superfluid and mott - insulator phases are investigated separately for ferromagnetic and antiferromagnetic interactions. mode entanglement is also discussed in the mott insulating phase.   the role of a small but nonzero angle between the polarization vectors of counter - propagating lasers forming the optical lattice on quantum correlations is investigated as well.
a super flavor factory, an asymmetric energy @xmath0 collider with a luminosity of order 10@xmath1 @xmath2s@xmath3, can provide a sensitive probe of new physics in the flavor sector of the standard model.   the success of the pep - ii and kekb asymmetric colliders @xcite in producing unprecedented luminosity above 10@xmath4 @xmath2s@xmath3 has taught us about the accelerator physics of asymmetric @xmath0 colliders in a new parameter regime.   furthermore, the success of the slac linear collider @xcite and the subsequent work on the international linear collider @xcite allow a new super - flavor collider to also incorporate linear collider techniques.   this note describes the parameters of an asymmetric flavor - factory collider at a luminosity of order 10@xmath1 @xmath2s@xmath3at the y(4s ) resonance and about 10@xmath5 @xmath2s@xmath3 at the @xmath6 production threshold.   such a collider would produce an integrated luminosity of about 10,000 fb@xmath3 ( 10 ab@xmath3 ) in a running year ( 10@xmath7 sec ) at the y(4s ) resonance. in the following note only the parameters relative to the y(4s )   resonance will be shown, the ones relative to the lower energy operations are still under study.
in this article, new regular incidence structures are presented.   they arise from sets of conics in the affine plane blown  up at its rational points.   the ldpc codes given by these incidence matrices are studied.   these sparse incidence matrices turn out to be redundant, which means that their number of rows exceeds their rank.   such a feature is absent from random ldpc codes and is in general interesting for the efficiency of iterative decoding.   the performance of some codes under iterative decoding is tested.   some of them turn out to perform better than regular gallager codes having similar rate and row weight.   * keywords : * incidence structures, ldpc codes, algebraic geometry, finite geometry, conics, linear systems of curves, blowing up.
the automatic extraction of acronyms and their meaning from corpora is an important sub - task of text mining.   it can be seen as a special case of string alignment, where a text chunk is aligned with an acronym.   alternative alignments have different cost, and ideally the least costly one should give the correct meaning of the acronym.   we show how this approach can be implemented by means of a 3-tape weighted finite - state machine ( 3-wfsm ) which reads a text chunk on tape 1 and an acronym on tape 2, and generates all alternative alignments on tape 3.   the 3-wfsm can be automatically generated from a simple regular expression.   no additional algorithms are required at any stage.   our 3-wfsm has a size of 27 states and 64 transitions, and finds the best analysis of an acronym in a few milliseconds.
the modification of hard jets in the quark gluon plasma ( qgp ) is studied using the matter event generator.   based on the higher twist formalism of energy loss, the matter event generator simulates the evolution of highly virtual partons through a medium.   these partons sampled from an underlying pythia kernel undergo splitting through a combination of vacuum and medium induced emission.   the momentum exchange with the medium is simulated via the jet transport coefficient @xmath0, which is assumed to scale with the entropy density at a given location in the medium.   the entropy density is obtained from a relativistic viscous fluid dynamics simulation ( vish2 + 1d ) in 2 + 1 space time dimensions.   results for jet and hadron observables are presented using an independent fragmentation model.   these proceedings will focus on the physics input and simulation details of the matter event generator as compared to a variety of test observables.   heavy - ion, jet, nuclear modification, monte - carlo
icecube have observed neutrinos which are presumably of extra - galactic origin. since specific sources have not yet been identified, we discuss what could be learned from the conceptual point of view.   we use a simple model for neutrino production from the interactions between nuclei and matter, and we focus on the description of the spectral shape and flavor composition observed by icecube.   our main parameters are spectral index, maximal energy, magnetic field, and composition of the accelerated nuclei.   we show that a cutoff at pev energies can be achieved by soft enough spectra, a cutoff of the primary energy, or strong enough magnetic fields.   these options, however, are difficult to reconcile with the hypothesis that these neutrinos originate from the same sources as the ultra - high energy cosmic rays. we demonstrate that heavier nuclei accelerated in the sources may be a possible way out if the maximal energy scales appropriately with the mass number of the nuclei. in this scenario,   neutrino observations can actually be used to test the uhecr acceleration mechanism.   we also emphasize the need for a volume upgrade of the icecube detector for future precision physics, for which the flavor information becomes a statistical meaningful model discriminator as qualitatively new ingredient.
we present an esr study at excitation frequencies of 9.4  ghz and 222.4  ghz of powders and single crystals of a prussian blue analogue ( pba ), rbmn[fe(cn)@xmath0@xmath1 h@xmath2o in which fe and mn undergoes a charge transfer transition between 175 and 300 k. the esr of pba powders, also reported by pregelj et al.@xcite is assigned to cubic magnetic clusters of mn@xmath3 ions surrounding fe(cn)@xmath4 vacancies.   the clusters are well isolated from the bulk and are superparamagnetic below 50 k. in single crystals various defects with lower symmetry are also observed.   spin - lattice relaxation broadens the bulk esr beyond observability.   this strong spin relaxation is unexpected above the charge transfer transition and is attributed to a mixing of the mn@xmath5-fe@xmath3 state into the prevalent mn@xmath3-fe@xmath5 state.
we propose an algorithm for the reconstruction of the signal induced by cosmic strings in the cosmic microwave background ( @xmath0 ), from radio - interferometric data at arcminute resolution.   radio interferometry provides incomplete and noisy fourier measurements of the string signal, which exhibits sparse or compressible magnitude of the gradient due to the kaiser - stebbins ( @xmath1 ) effect. in this context   the versatile framework of compressed sensing naturally applies for solving the corresponding inverse problem.   our algorithm notably takes advantage of a model of the prior statistical distribution of the signal fitted on the basis of realistic simulations. enhanced performance relative to the standard @xmath2 algorithm   is demonstrated by simulated observations under noise conditions including primary and secondary @xmath0 anisotropies.       techniques : image processing  techniques : interferometric  cosmic microwave background.
in this paper, we propose a masked photocathode inside a photoinjector for generating high brightness electron beam. instead of mounting the photocathode onto an electrode,   an electrode with small hole is used as a mask to shield the photocathode from the accelerating vacuum chamber.   using such a masked photocathode will make the replacement of photocathode material easy by rotating the photocathode behind the electrode into the hole.   furthermore, this helps reduce the dark current or secondary electron emission from the photocathode material.   the masked photocathode also provides transverse cut - off to a gaussian laser beam that reduces electron beam emittance growth from nonlinear space - charge effects.
we present an analytic derivation of the temporal dependence of the perpendicular transport coefficient of charged particles in magnetostatic turbulence, for times smaller than the time needed to charged particles to travel the turbulence correlation length.   this time window is left unexplored in most transport models. in our analysis   all magnetic scales are taken to be much larger than the particle gyroradius, so that perpendicular transport is assumed to be dominated by the guiding center motion.   particle drift from the local magnetic field lines and magnetic field lines random walk are evaluated separately for slab and 3d isotropic turbulence.   contributions of wavelength scales shorter and longer than the turbulence coherence length are compared.   in contrast to slab case, particles in 3d isotropic turbulence unexpectedly diffuse from local magnetic field lines ; this result questions the common assumption that particle magnetization is independent on turbulence geometry. extensions of this model will allow for a study of solar wind anisotropies.
in this work we propose schemes for joint model - order and step - size adaptation of reduced - rank adaptive filters.   the proposed schemes employ reduced - rank adaptive filters in parallel operating with different orders and step sizes, which are exploited by convex combination strategies. the reduced - rank adaptive filters used in the proposed schemes are based on a joint and iterative decimation and interpolation ( jidf ) method recently proposed.   the unique feature of the jidf method is that it can substantially reduce the number of coefficients for adaptation, thereby making feasible the use of multiple reduced - rank filters in parallel.   we investigate the performance of the proposed schemes in an interference suppression application for cdma systems.   simulation results show that the proposed schemes can significantly improve the performance of the existing reduced - rank adaptive filters based on the jidf method.   adaptive filters, convex combinations, model - order selection, reduced - rank adaptive filters.
it is generally considered that an atomic nucleus is always compact. based on the isospin - dependent boltzmann nuclear transport model, here   i show that large block nuclear matter or excited nuclear matter may both be hollow. and   the size of inner bubble in these matter is affected by the charge number of nuclear matter.   existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.
we have spectroscopically identified 77 new members of the cygnus a cluster, bringing the total to 118 galaxies consistent with cluster membership.   we use these data combined with the results from x - rays to deduce a dynamical model for the system.   the data are consistent with a cluster - cluster merger viewed at a projection angle of 30 - 45@xmath0, 0.2 - 0.6 gyr prior to core passage.   we estimate the richness of the combined cluster system at abell richness class 2 or greater, suggesting the merger of two richness class @xmath1 clusters.
the numerical calculations for tadpole - improved @xmath0 lattice gauge theory in three - dimensions on anisotropic lattices have been performed using standard path integral monte carlo techniques. using average plaquette tadpole renormalization scheme,   simulations were done with temporal lattice spacings much smaller than the spatial ones and results were obtained for the string tension, the renormalized anisotropy and scalar glueball masses.   we find, by comparing the ` regular'and ` sideways'potentials, that tadpole improvement results in very little renormalization of the bare anisotropy and reduces the discretization errors in the static quark potential and in the glueball masses.
we introduce a new matrix function for studying graphs and real - world networks based on a double - factorial penalization of walks between nodes in a graph.   this new matrix function is based on the matrix error function.   we find a very good approximation of this function using a matrix hyperbolic tangent function.   we derive a communicability function, a subgraph centrality and a double - factorial estrada index based on this new matrix function.   we obtain upper and lower bounds for the double - factorial estrada index of graphs, showing that they are similar to those of the single - factorial estrada index.   we then compare these indices with the single - factorial one for simple graphs and real - world networks.   in particular, we study the problem of identification of essential proteins in yeast.   we conclude that for this practical problem the structural information contained in the longer walks on graphs is not as relevant as the one contained in the shorter ones for characterizing network structure.   more practical applications of the new indices are needed to extract more definitive conclusions on their use for analyzing complex networks.   matrix error function ; matrix tanh function ; communicability functions ; double - factorial ; protein interactions ; complex networks
given a sequence composed of a limit number of characters, we try to  read " it as a  text ".   this involves to segment the sequence into  words ".   the difficulty is to distinguish good segmentation from enormous number of random ones. aiming at revealing the nonrandomness of the sequence as strongly as possible, by applying maximum likelihood method  , we find a quantity called * segmentation entropy * that can be used to fulfill the duty.   contrary to commonplace where maximum entropy principle was applied to obtain good solution, we choose to _ minimize _ the segmentation entropy to obtain good segmentation.   the concept developed in this letter can be used to study the noncoding dna sequences, e.g., for regulatory elements prediction, in eukaryote genomes.
existing optimal control protocols for mitigating the effects of relaxation and/or rf inhomogeneity on broadband pulse performance are extended to the more difficult problem of designing robust, refocused, frequency selective excitation pulses. for the demanding case of and equal to the pulse length, anticipated signal losses can be significantly reduced while achieving nearly ideal frequency selectivity.   improvements in performance are the result of allowing residual unrefocused magnetization after applying relaxation - compensated selective excitation by optimized pulses ( rc - sebop ).   we demonstrate simple pulse sequence elements for eliminating this unwanted residual signal.   selective excitation ; rc - sebob ; relaxation ; @xmath0 relaxation ; @xmath1 relaxation ; optimal control theory
one of the important factors governing the growth morphology of materials is the interface kinetic coefficient @xmath0, which is the proportionality constant between the velocity of solid - liquid interface and undercooling.   we employ ginzburg - landau ( gl ) free energy functional to derive an analytical expression of kinetic coefficients.   the anisotropy of kinetic coefficients naturally arise from the broken symmetry at the solid - liquid interface for various crystalline orientations.   the analytical expression of kinetic coefficients is compared to mikheev - chernov theory [ j. cryst.   growth * 112 *, 591 ( 1991 ) ] derived from hydrodynamic equations. in addition, we use equilibrium density wave profiles to evaluate kinetic coefficients and compare them with that from md simulations.   our results are in good agreement with mikheev - chernov theory and md simulations and shed lights on a possible origin of anisotropy of interfacial kinetics.
given a locally consistent set of reduced density matrices, we construct approximate density matrices which are globally consistent with the local density matrices we started from when the trial density matrix has a tree structure.   we employ the cavity method of statistical physics to find the optimal density matrix representation by slowly decreasing the temperature in an annealing algorithm, or by minimizing an approximate bethe free energy depending on the reduced density matrices and some cavity messages originated from the bethe approximation of the entropy.   we obtain the classical bethe expression for the entropy within a naive ( mean - field ) approximation of the cavity messages, which is expected to work well at high temperatures. in the next order of the approximation  , we obtain another expression for the bethe entropy depending only on the diagonal elements of the reduced density matrices. in principle  , we can improve the entropy approximation by considering more accurate cavity messages in the bethe approximation of the entropy.   we compare the annealing algorithm and the naive approximation of the bethe entropy with exact and approximate numerical simulations for small and large samples of the random transverse ising model on random regular graphs.
extensive monte - carlo simulations were performed to study bond percolation on the simple cubic ( s.c. ), face - centered cubic ( f.c.c. ), and body - centered cubic ( b.c.c. ) lattices, using an epidemic kind of approach.   these simulations provide very precise values of the critical thresholds for each of the lattices : @xmath0s.c.@xmath1, @xmath0f.c.c.@xmath2, and @xmath0b.c.c.@xmath3. for @xmath4 close to @xmath5,   the results follow the expected finite - size and scaling behavior, with values for the fisher exponent @xmath6 @xmath7, the finite - size correction exponent @xmath8 @xmath9, and the scaling function exponent @xmath10 @xmath11 confirmed to be universal.   # 1@xmath12#1
we present a generative probabilistic model for a tidal stream and demonstrate how this model is used to constrain the galactic potential.   the model takes advantage of the simple structure of a stream in angle and frequency space for the correct potential.   we investigate how the method performs on full 6d mock stream data, and mock data with outliers included.   as currently formulated the technique is computationally costly when applied to data with large observational errors, but we describe several modifications that promise to make the technique computationally tractable.    the galaxy : kinematics and dynamics - the galaxy : structure - galaxies : kinematics and dynamics - methods : numerical
the galactic center hosts several hundred early - type stars, about 20% of which lie in the so - called clockwise disk, while the remaining 80% do not belong to any disks. the circumnuclear ring ( cnr ),   a ring of molecular gas that orbits the supermassive black hole ( smbh ) with a radius of @xmath0, has been claimed to induce precession and kozai - lidov oscillations onto the orbits of stars in the innermost parsec.   we investigate the perturbations exerted by a gas ring on a nearly - keplerian stellar disk orbiting a smbh by means of combined direct n - body and smoothed particle hydrodynamics simulations.   we simulate the formation of gas rings through the infall and disruption of a molecular gas cloud, adopting different inclinations between the infalling gas cloud and the stellar disk.   we find that a cnr - like ring is not efficient in affecting the stellar disk on a timescale of @xmath1.   in contrast, a gas ring in the innermost @xmath2 induces precession of the longitude of the ascending node @xmath3, significantly affecting the stellar disk inclination.   furthermore, the combined effect of two - body relaxation and @xmath3-precession drives the stellar disk dismembering, displacing the stars from the disk.   the impact of precession on the star orbits is stronger when the stellar disk and the inner gas ring are nearly coplanar.   we speculate that the warm gas in the inner cavity might have played a major role in the evolution of the clockwise disk.
the direct liquid injection chemical vapor deposition ( dli - cvd ) technique has been used for the growth of cobalt ferrite ( cfo ) films on ( 100)-oriented mgal@xmath0o@xmath1 ( mao ) substrates.   smooth and highly epitaxial cobalt ferrite thin films, with the epitaxial relationship @xmath2 \parallel \mathrm{cfo } ( 100)\:$ ], are obtained under optimized deposition conditions. the films exhibit bulk - like structural and magnetic properties with an out - of - plane lattice constant of @xmath3 and a saturation magnetization of @xmath4 at room temperature.   the raman spectra of films on mgal@xmath0o@xmath1 support the fact that the fe@xmath5- and the co@xmath6-ions are distributed in an ordered fashion on the b - site of the inverse spinel structure.   the dli - cvd technique has been extended for the growth of smooth and highly oriented cobalt ferrite thin films on a variety of other substrates, including mgo, and piezoelectric lead magnesium niobate - lead titanate and lead zinc niobate - lead titanate substrates.
a comprehensive study of doped rvb states is performed.   it reveals a fundamental connection between superconductivity and quantum spin fluctuations in underdoped cuprates : _   cooper pair hopping _ strongly reduces the local magnetization @xmath0.   this effect pertains to recent muon spin rotation measurements in which @xmath0 varies weakly with hole doping in the poorly conducting regime, but drops precipitously above the onset of superconductivity.   gutzwiller mean field approximation ( ga ) is found to agree with numerical monte carlo calculation.   ga shows for example that for a bond amplitude @xmath1, spin spin correlations decay exponentially with a correlation length @xmath2.   expectation value of the heisenberg model is found to be correlated with average loop density.
i describe a bayesian method to account for measurement errors in linear regression of astronomical data.   the method allows for heteroscedastic and possibly correlated measurement errors, and intrinsic scatter in the regression relationship.   the method is based on deriving a likelihood function for the measured data, and i focus on the case when the intrinsic distribution of the independent variables can be approximated using a mixture of gaussians.   i generalize the method to incorporate multiple independent variables, non - detections, and selection effects ( e.g., malmquist bias ).   a gibbs sampler is described for simulating random draws from the probability distribution of the parameters, given the observed data.   i use simulation to compare the method with other common estimators.   the simulations illustrate that the gaussian mixture model outperforms other common estimators and can effectively give constraints on the regression parameters, even when the measurement errors dominate the observed scatter, source detection fraction is low, or the intrinsic distribution of the independent variables is not a mixture of gaussians.   i conclude by using this method to fit the x - ray spectral slope as a function of eddington ratio using a sample of 39 @xmath0 radio - quiet quasars.   i confirm the correlation seen by other authors between the radio - quiet quasar x - ray spectral slope and the eddington ratio, where the x - ray spectral slope softens as the eddington ratio increases.   idl routines are made available for performing the regression.
a model for network panel data is discussed, based on the assumption that the observed data are discrete observations of acontinuous - time markov process on the space of all directed graphs on a given node set, in which changes in tie variables are independent conditional on the current graph.   the  model for tie changes is parametric and designed for applications to social network analysis, where the network dynamics can be interpreted as being generated by choices made by the social actors represented by the nodes of the graph.   an algorithm for calculating the maximum likelihood estimator is presented, based on data augmentation and stochastic approximation.   an application to an evolving friendship network is given and a small simulation study is presented which suggests that for small data sets the maximum likelihood estimator is more efficient than the earlier proposed method of moments estimator.   ,     +   .
based on first - principles electron structure calculations and employing the frozen - magnon approximation we study the exchange interactions in a series of transition - metal binary alloys crystallizing in the zinc - blende structure and calculate the curie temperature within both the mean - field approximation ( mfa ) and random - phase approximation ( rpa ).   we study two cr compounds, cras and crse, and four mn compounds : mnsi, mnge, mnas and mnc.   mnc, mnsi and mnge are isovalent to cras and mnas is isoelectronic with crse.   ferromagnetism is particular stable for cras, mnsi and mnge : all three compounds show curie temperatures around 1000 k. on the other hand, crse and mnas show a tendency to antiferromagnetism when compressing the lattice. in mnc   the half - metallic gap is located in the majority - spin channel contrary to the other five compounds.   the large half - metallic gaps, very high curie temperatures, the stability of the ferromagnetism with respect to the variation of the lattice parameter and a coherent growth on semiconductors make mnsi and cras most promising candidates for the use in spintronics devises.
although the framework for oscillations of the three neutrino flavors in the standard model has been convincingly established, indications persist that it may be incomplete.   challenges are coming from the lsnd and miniboone short - baseline experiments, from the neutrino sources used in the gallex and sage solar neutrino experiments and, more recently, from an a - posteriori analysis of reactor neutrino experiments.   one way to accommodate the reported  anomalies ", if real, is to introduce one or more sterile neutrinos in the mass range @xmath0.   tev atmospheric neutrinos propagating through the earth undergo resonant oscillations in the presence of sterile neutrinos ; a clear signature in a neutrino telescope like icecube is the the change in shape of the zenith - energy distribution of the atmospheric neutrinos.   icecube detects more than 100,000 atmospheric neutrinos per year.   statistics do not limit such a measurement, but the uncertainties in modeling the expectations of the conventional 3-flavor scenario, including the systematics of the detector, do.   we review the status and future perspectives of understanding the zenith and energy response of icecube in the tev energy range.
we present an extension of the spin - adapted configuration - interaction method for the computation of four electrons in a quasi two - dimensional quantum dot. by a group - theoretical decomposition of the basis set and working with relative and center - of - mass coordinates we obtain an analytical identification of all spurious center - of - mass states of the coulomb - interacting electrons.   we find a substantial reduction in the basis set used for numerical computations. at the same time we increase the accuracy compared to the standard spin - adapted configuration - interaction method ( saci ) due to the absence of distortions caused by an unbalanced cut - off of center - of - mass excitations.   dedicated to margarita and vladimir manko on the occasion of their 150th birthday.
for a physical or biological model whose dynamics is described by a higher order difference equation @xmath0, we propose a version of a target oriented control @xmath1, with @xmath2, @xmath3. in ecological systems  , the method incorporates harvesting and recruitment and for a wide class of @xmath4, allows to stabilize ( locally or globally ) a fixed point of @xmath4. if a point which is not a fixed point of @xmath4 has to be stabilized, the target oriented control is an appropriate method for achieving this goal. as a particular case  , we consider pest control applied to pest populations with delayed density - dependence.   this corresponds to a proportional feedback method, which includes harvesting only, for higher order equations.   chaos, target oriented control, higher order difference equation, globally asymptotically stable fixed point, delay ricker model, pielou equation    * ams subject classification : * 93d15 ( primary ), 92d25, 39a30, 93c55 ( secondary )
this is comment to preprint arxiv:1409.7459 by y. tada, wenxing nie and m. oshikawa `` orbital angular momentum and spectral flow in two dimensional chiral superfluids '', @xcite where the effect of spectral flow along the edge states on the magnitude of the orbital angular momentum is discussed.   the general conclusion of the preprint on the essential reduction of the angular momentum for the higher values of chirality, @xmath0, is confirmed.   however, we show that if parity is violated, the reduction of the angular momentum takes place also for the @xmath1-wave superfluids with @xmath2.
the role played by the effective residual interaction in the transverse nuclear response for quasi   free electron scattering is discussed.   the analysis is done by comparing different calculations performed in the random  phase approximation and ring approximation frameworks.   the importance of the exchange terms in this energy region is investigated and the changes on the nuclear responses due to the modification of the interaction are evaluated. the calculated quasi   elastic responses show clear indication of their sensibility to the details of the interaction and this imposes the necessity of a more careful study of the role of the different channels of the interaction in this excitation region.
the anisotropy parameter of two - dimensional equilibrium clusters of site percolation process in long - range self - affine correlated structures are studied numerically.   we use a fractional brownian motion(fbm ) statistic to produce both persistent and anti - persistent long - range correlations in 2-d models.   it is seen that self affinity makes the shape of percolation clusters slightly more isotropic. moreover, we find that the sign of correction to scaling term is determined by the nature of correlation. for persistent correlation   the correction to scaling term adds a negative contribution to the anisotropy of percolation clusters, while for the anti - persistent case it is positive.    *   the anisotropy of two dimensional percolation clusters of self - affine models *    fatemeh ebrahimi + _ department of physics, university of birjand, birjand, iran, 97175 - 615 + _
we show the planned upgrade of a cavity qed experimental apparatus.   the system consists of an optical cavity and an ensemble of ultracold @xmath0rb atoms coupled to its mode.   we propose enhancements to both.   first, we document the building process for a new cavity, with a planned finesse of @xmath120000.   we address problems of maintaining mirror integrity during mounting and improving vibration isolation.   second, we propose improvements to the cold atom source in order to achieve better optical pumping and control over the flux of atoms. we consider a 2-d optical molasses for atomic beam deflection, and   show computer simulation results for evaluating the design.   we also examine the possibility of all - optical atomic beam focusing, but find that it requires unreasonable experimental parameters.
while the idea of using the operator product expansion ( ope ) to extract the strong coupling from hadronic @xmath0 decay data is not new, there is an ongoing controversy over how to include quark - hadron `` duality violations '' ( _ i.e. _, resonance effects ) which are not described by the ope.   one approach attempts to suppress duality violations enough that they might become negligible, but pays the price of an uncontrolled ope truncation.   we critically examine a recent analysis using this approach and show that it fails to properly account for non - perturbative effects, making the resulting determination of the strong coupling unreliable. in a different approach duality violations are taken into account with a model, avoiding the ope truncation.   this second approach provides a self - consistent determination of the strong coupling from @xmath0 decays.
let @xmath0 be the partition polynomial @xmath1 where @xmath2 is the number of partitions of @xmath3 with @xmath4 parts.   we emphasize the computational experiments using degrees up to @xmath5 to discover the asymptotics of these polynomials.   surprisingly, the asymptotics of @xmath0 have two scales of orders @xmath3 and @xmath6 and in three different regimes inside the unit disk.   consequently, the zeros converge to network of curves inside the unit disk given in terms of the dilogarithm.
we present a theory which can explain the micromaser as well as its optical counterpart, the microlaser, for appropriate values of dissipative parameters.   we show that, in both the the cases, the cavity radiation fields can have sub - poissonian photon statistics.   we further analyse if it is possible to attain a fock state of the radiation field.   the microlaser is precluded for such analysics due to the damping of its lasing levels making transitions at optical frequencies.   hence, we focus our attention on the micromaser and our exact simulation of the dynamics shows that it is not possible to generate a fock state of the cavity radiation field.    2
the damping of a massless fermion coupled to a massless scalar particle at finite temperature is considered using the braaten - pisarski resummation technique.   first the hard thermal loop diagrams of this theory are extracted and effective green s functions are constructed. using these effective green s functions the damping rate of a soft yukawa fermion   is calculated.   this rate provides the most simple example for the damping of a soft particle. to leading order   it is proportional to @xmath0, whereas the one of a hard fermion is of higher order.
_ abstract _ : interest in the protein folding problem has motivated a wide range of theoretical and experimental studies of the kinetics of the collapse of flexible homopolymers. in this paper   a phenomenological model is proposed for the kinetics of the early stages of homopolymer collapse following a quench from temperatures above to below the @xmath0 temperature. in the first stage,   nascent droplets of the dense phase are formed, with little effect on the configurations of the bridges that join them.   the droplets then grow by accreting monomers from the bridges, thus causing the bridges to stretch. during these two stages   the overall dimensions of the chain decrease only weakly. further growth of the droplets is accomplished by the shortening of the bridges, which causes the shrinking of the overall dimensions of the chain.   the characteristic times of the three stages respectively scale as @xmath1, @xmath2 and @xmath3, where @xmath4 is the degree of polymerization of the chain.   epsf acknowledgement algorithm axiom claim conclusion condition conjecture corollary criterion definition example exercise lemma notation problem proposition remark solution summary    2truein    2
@xmath0-body simulations have unveiled several apparently universal properties of dark matter halos, including a cusped density profile, a power - law pseudo phase - space density @xmath1, and a linear @xmath2 relation between the density slope and the velocity anisotropy.   we present a family of self - consistent phase - space distribution functions @xmath3, based on the dehnen - mclaughlin jeans models, that incorporate these universal properties very accurately.   these distribution functions, derived using a quadratic programming technique, are analytical, positive and smooth over the entire phase space and are able to generate four - parameter velocity anisotropy profiles @xmath4 with arbitrary asymptotic values @xmath5 and @xmath6.   we discuss the orbital structure of six radially anisotropic systems in detail and argue that, apart from its use for generating initial conditions for @xmath0-body studies, our dynamical modeling provides a valuable complementary approach to understand the processes involved in the formation of dark matter halos.
we demonstrate how a quantum otto engine ( qoe ) can be implemented using a single ion and an always - on thermal environment  . the internal degree of freedom of the ion is chosen as the working fluid, while the motional degree of freedom can be used as the cold bath.   we show, that by adiabatically changing the local magnetic field, the work efficiency can be asymptotically made unity.   we propose a projective measurement of the internal state of the ion that mimics the release of heat into the cold bath during the engine cycle. in our proposal,   the coupling to the hot and the cold baths need not be switched off and on in an alternative fashion during the engine cycle, unlike other existing proposals of qoe.   this renders the proposal experimentally feasible using the available tapped - ion engineering technology.
white dwarfs are the end product of the lifes of intermediate- and low - mass stars and their evolution is described as a simple cooling process.   recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval.   we show here that the shape of the bright branch of this function is only sensitive to the averaged cooling rate of white dwarfs and we propose to use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle.   our results indicate that the inclusion of the emission of axions in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function.   the best fit is obtained for @xmath0  mev, where @xmath1 is the mass of the axion and @xmath2 is a free parameter.   we also show that values larger than 10 mev are clearly excluded.   the existing theoretical and observational uncertainties do not yet allow the confirmation of the existence of axions, but our results clearly show that if their mass is of the order of few mev, the white dwarf luminosity function is sensitive enough to detect their existence.
we study the optical counterpart of the black - hole x - ray binary lmc x@xmath03, by using _   xmm - newton / om _ observations carried out during a low - hard x - ray state. we derive a better constraint for the temperature, mass and radius of the companion star, and we show that the star is likely to be a @xmath1 b5 subgiant filling its roche lobe.   taking into account the effect of x - ray irradiation, we suggest a value @xmath2 for the mass function in this system, lower than previously thought ; we provide a more accurate lower limit to the mass of the compact object.
we derive an analytic expression for the mean magnification due to strong gravitational lensing, using a simple lens model, a singular isothermal sphere embedded in an external shear field.   we compute separate expressions for 2-image and 4-image lensing. for 4-image lensing,   the mean magnification takes a particularly simple form : @xmath0, where @xmath1 is the external shear.   we compare our analytic results to a numerical evaluation of the full magnification distribution.   the results can be used to understand the magnification bias that favors the discovery of four - image systems over two - image systems in flux - limited lens surveys.
we experiment with injecting a continuous stream of gas into a shallow liquid, similar to how one might blow into a straw placed at the bottom of a near - empty drink. by varying the angle of the straw ( here a metal needle )  , we observe a variety of dynamics, which we film using a high - speed camera.   most noteworthy is an intermediate regime in which cyclical jets erupt from the air - liquid interface and breakup into air - born droplets.   these droplets trace out a parabolic trajectory and bounce on the air - liquid interface before eventually coalescing.   the shape of each jet, as well as the time between jets, is remarkably similar and leads to droplets with nearly identical trajectories.   the following article accompanies the linked fluid dynamics video ( http://ecommons.library.cornell.edu/bitstream/1813/11469/3/bird_dfd2008_mpeg1.mpg, http://ecommons.library.cornell.edu/bitstream/1813/11469/2/bird_dfd2008_mpeg2.mpg ) submitted to the gallery of fluid motion in 2008.
the form factor of a quantum graph is a function measuring correlations within the spectrum of the graph.   it can be expressed as a double sum over the periodic orbits on the graph.   we propose a scheme which allows one to evaluate the periodic orbit sum for a special family of graphs and thus to recover the expression for the form factor predicted by the random matrix theory.   the scheme, although producing the expected answer, undercounts orbits of a certain structure, raising doubts about an analogous summation recently proposed for quantum billiards.
estimates of velocities from time series of photospheric and/or chromospheric vector magnetograms can be used to determine fluxes of magnetic energy ( the poynting flux ) and helicity across the magnetogram layer, and to provide time - dependent boundary conditions for data - driven simulations of the solar atmosphere above this layer.   velocity components perpendicular to the magnetic field are necessary both to compute these transport rates and to derive model boundary conditions. here  , we discuss some possible approaches to estimating perpendicular flows from magnetograms.   since doppler shifts contain contributions from flows parallel to the magnetic field, perpendicular velocities are not generally recoverable from doppler shifts alone.   the induction equation s vertical component relates evolution in @xmath0 to the perpendicular flow field, but has a finite null space, meaning some `` null '' flows, e.g., motions along contours of normal field, do not affect @xmath0.   consequently, additional information is required to accurately specify the perpendicular flow field.   tracking methods, which analyze @xmath1 in a neighborhood, have a long heritage, but other approaches have recently been developed. in a recent paper  , several such techniques were tested using synthetic magnetograms from mhd simulations. here  , we use the same test data to characterize : 1 ) the ability of the induction equation s normal component, by itself, to estimate flows ; and 2 ) a tracking method s ability to recover flow components that are perpendicular to @xmath2 and parallel to contours of @xmath0.   this work has been supported by nasa heliophysics theory grant nng05g144 g.
the so - called `` early activity '' of comet 67p / churyumov - gerasimenko has been observed to originate mostly in parts of the concave region or `` neck '' between its two lobes.   since activity is driven by the sublimation of volatiles, this is a puzzling result because this area is less exposed to the sun and is therefore expected to be cooler on average @xcite.   we used a thermophysical model that takes into account thermal inertia, global self - heating, and shadowing, to compute surface temperatures of the comet.   we found that, for every rotation in the august   december 2014 period, some parts of the neck region undergo the fastest temperature variations of the comet s surface precisely because they are shadowed by their surrounding terrains.   our work suggests that these fast temperature changes are correlated to the early activity of the comet, and we put forward the hypothesis that erosion related to thermal cracking is operating at a high rate on the neck region due to these rapid temperature variations.   this may explain why the neck contains some ice as opposed to most other parts of the surface @xcite and why it is the main source of the comet s early activity @xcite.    in a broader context,   these results indicate that thermal cracking can operate faster on atmosphereless bodies with significant concavities than implied by currently available estimates @xcite.
we report a 3d magnetohydrodynamics simulation that studies the formation of dipolarization fronts during magnetotail reconnection.   the crucial new feature uncovered in the present 3d simulation is that the process of reconnection produces flux ropes developing within the reconnection region.   these flux ropes are unstable to the kink mode and introduce a spontaneous structure in the dawn - dusk direction.   the dipolarization fronts forming downstream of reconnection are strongly affected by the kinking ropes. at the fronts,   a density gradient is present with opposite direction to that of the acceleration field and leads to an interchange instability.   we present evidence for a causal link where the perturbations of the kinking flux ropes with their natural and well defined scales drive and select the scales for the interchange mode in the dipolarization fronts.   the results of the simulation are validated against measured structures observed by the themis mission.
we have proposed a qualitative model for the structure of binary systems similar to pd  er alloys, which explains their nonmonotonic relaxation after the hydrogen saturation.   it is based on the assumption that such a solid solution involves two kind heterogeneities.   the former are caused by spinodal decomposition of the initially homogeneous state of the solid solution into the phases enriched and depleted of er atoms.   the latter are crystalline defects that trap an additional amount of er atoms, which leads also to their local accumulation, changing the defect properties.   hydrogen atoms penetrating into the solid disturb the equilibrium of both the phase separation and the defect saturation with er atoms, causing redistribution of er atoms.   the diffusion fluxes give rise to the motion of the interface between the two phases that is responsible for time variations, for example, in the relative volume of the enriched phase observed experimentally.   we have found the conditions when the interface motion can change the direction during the system relaxation to a new equilibrium state.   the latter effect is, from our point of view, the essence of the hydrogen induced nonmonotonic relaxation observed in such systems.   the numerical simulation confirms the basic assumptions.
in this paper we report results for magnetic observables of finite spin clusters composed of s  =  1/2 ions.   we consider clusters of two, three and four spins in distinct spatial arrangements, with isotropic heisenberg interactions of various strengths between ion pairs.   in addition to the complete set of energy eigenvalues and eigenvectors, specific heat and magnetic susceptibility, we also quote results for the single crystal and powder average inelastic neutron scattering structure factors.   examples of the application of these results to experimental systems are also discussed.
we present near - ir spectroscopy of red supergiant ( rsg ) stars in ngc6822, obtained with the new vlt - kmos instrument. from comparisons with model spectra in the @xmath0-band we determine the metallicity of 11 rsgs, finding a mean value of [ @xmath1  =  @xmath20.52@xmath30.21 which agrees well with previous abundance studies of young stars and hii regions.   we also find an indication for a low - significance abundance gradient within the central 1kpc. we compare our results with those derived from older stellar populations and investigate the difference using a simple chemical evolution model. by comparing the physical properties determined for rsgs in ngc6822 with those derived using the same technique in the galaxy and the magellanic clouds,   we show that there appears to be no significant temperature variation of rsgs with respect to metallicity, in contrast with recent evolutionary models.
we have studied constraints on the equation of state, @xmath0, and speed of sound, @xmath1, of the dark energy from a joint analysis of data from the cosmic microwave background, large scale structure and type - ia supernovae.   we find that current observations have no significant sensitivity to @xmath1.   however, there is a slight difference between models in which there are no dark energy perturbations and models in which dark energy behaves as a fluid. assuming that there are no dark energy perturbations shifts the allowed region for @xmath0 to slightly higher values. at present models with and without dark energy perturbations   provide roughly equally good fits to observations, but the difference is potentially important for future parameter estimations.   finally, we have also performed error forecasts for future measurements of @xmath1.
we present in this paper our work regarding simulating a type of p system known as a spiking neural p system ( snp system ) using graphics processing units ( gpus ).   gpus, because of their architectural optimization for parallel computations, are well - suited for highly parallelizable problems. due to the advent of general purpose gpu computing in recent years, gpus are not limited to graphics and video processing alone, but include computationally intensive scientific and mathematical applications as well  . moreover p systems, including snp systems, are inherently and maximally parallel computing models whose inspirations are taken from the functioning and dynamics of a living cell.   in particular, snp systems try to give a modest but formal representation of a special type of cell known as the neuron and their interactions with one another.   the nature of snp systems allowed their representation as matrices, which is a crucial step in simulating them on highly parallel devices such as gpus.   the highly parallel nature of snp systems necessitate the use of hardware intended for parallel computations.   the simulation algorithms, design considerations, and implementation are presented. finally, simulation results, observations, and analyses using an snp system that generates all numbers in @xmath0 - \{@xmath1 } are discussed, as well as recommendations for future work.   * key words : * membrane computing, parallel computing, gpu computing
the total entropy production generated by the dynamics of an externally driven systems exchanging energy and matter with multiple reservoirs and described by a master equation is expressed as the sum of three contributions, each corresponding to a distinct mechanism for bringing the system out of equilibrium : nonequilibrium initial conditions, external driving, and breaking of detailed balance.   we derive three integral fluctuation theorems ( fts ) for these contributions and show that they lead to the following universal inequality : an arbitrary nonequilibrium transformation always produces a change in the total entropy production greater or equal than the one produced if the transformation is done very slowly ( adiabatically ).   previously derived fluctuation theorems can be recovered as special cases.   we show how these fts can be experimentally tested by performing the counting statistics of the electrons crossing a single level quantum dot coupled to two reservoirs with externally varying chemical potentials.   the entropy probability distributions are simulated for driving protocols ranging from the adiabatic to the sudden switching limit.
we present new results on the statistical hadronization of heavy quarks at sps, rhic and lhc energies.   several new aspects are considered, among them a separation of the collision geometry into a `` core '' and a `` corona '' part and an estimate of the annihilation rate of charm quark in a hot plasma, together with a critical assessment of its influence on the results. for rhic energies   we investigate the centrality dependence of @xmath0 production focusing on the model results for different values of the charm production cross section, including its theoretical and experimental uncertainty.   we also study, within this model, the rapidity dependence of the @xmath0 yield.   recent rhic data from the phenix experiment are well reproduced. at lhc energy, we update our model predictions for the centrality dependence of the @xmath0 yield and investigate as well the rapidity dependence.   we also discuss the transverse momentum distributions of @xmath0 mesons expected from the model and provide predictions for a range of values of the expansion velocity at chemical freeze - out. finally, we extend the model to predict @xmath1 yields in pb+pb collisions at lhc energy.   ,   ,   ,
we study properties of a trapped dipolar bose - einstein condensate ( bec ) in a circular ring or a spherical shell using the mean - field gross - pitaevskii equation. in the case of the ring - shaped trap we consider different orientations of the ring with respect to the polarization direction of the dipoles. in the presence of long - range anisotropic   dipolar and short - range contact interactions, the anisotropic density distribution of the dipolar bec in both traps is discussed in detail.   the stability condition of the dipolar bec in both traps is illustrated in phase plot of dipolar and contact interactions.   we also study and discuss the properties of a vortex dipolar bec in these traps.
in this paper the duality correspondence between fermion - antifermion and difermion interaction channels is established in two ( 2 + 1)-dimensional gross - neveu type models with a fermion number chemical potential @xmath0 and a chiral chemical potential @xmath1. the role and influence of this property on the phase structure of the models   are investigated.   in particular, it is shown that the chemical potential @xmath1 promotes the appearance of dynamical chiral symmetry breaking, whereas the chemical potential @xmath0 contributes to the emergence of superconductivity.
we present a formalism able to generalise to a relativistically covariant scheme the standard nuclear shell model.   we show that, using some generalised nuclear green s functions and their lehmann representation we can define the relativistic equivalent of the non relativistic single particle wave function ( not loosing, however, the physical contribution of other degrees of freedom, like mesons and antinucleons ).   it is shown that the mass operator associated to the nuclear green s function can be approximated with the equivalent of a shell - model potential and that the corresponding `` single particle wave functions '' can be easily derived in a specified frame of reference and then boosted to any other system, thus fully restoring the lorentz covariance.   # 1 # 1 # 1 # 1 p
protein structure alignment is a fundamental problem in computational and structural biology.   while there has been lots of experimental / heuristic methods and empirical results, very little is known regarding the algorithmic / complexity aspects of the problem, especially on protein local structure alignment.   a well - known measure to characterize the similarity of two polygonal chains is the famous frchet distance and with the application of protein - related research, a related discrete frchet distance has been used recently. in this paper, following the recent work of jiang, _ et al.   _ we investigate the protein local structural alignment problem using bounded discrete frchet distance. given @xmath0 proteins ( or protein backbones, which are 3d polygonal chains ), each of length @xmath1, our main results are summarized as follows.    *   if the number of proteins, @xmath0, is not part of the input, then the problem is np - complete ; moreover, under bounded discrete frchet distance it is np - hard to approximate the maximum size common local structure within a factor of @xmath2.   these results hold both when all the proteins are static or when translation / rotation are allowed. *   if the number of proteins, @xmath0, is a constant, then there is a polynomial time solution for the problem.   * keywords * : protein structure alignment, frchet distance, discrete frchet distance, approximation, np - hardness
we use the canonical hartree - fock - bogoliubov basis to implement a completely self - consistent quasiparticle - random - phase approximation with arbitrary skyrme energy density functionals and density - dependent pairing functionals.   the point of the approach is to accurately describe multipole strength functions in spherical even - even nuclei, including weakly - bound drip - line systems.   we describe the method and carefully test its accuracy, particularly in handling spurious modes. to illustrate our approach,   we calculate isoscalar and isovector monopole, dipole, and quadrupole strength functions in several sn isotopes, both in the stable region and at the drip lines.
employing the graded versions of the yang - baxter equation and the reflection equations, we construct two kinds of integrable impurities for a small - polaron model with general open boundary conditions : ( a ) we shift the spectral parameter of the local lax operator at arbitrary sites in the bulk, and ( b ) we embed the impurity fermion vertex at each boundary of the chain. the hamiltonians with different types of impurity terms   are given explicitly.   the bethe ansatz equations, as well as the eigenvalues of the hamiltonians, are constructed by means of the quantum inverse scattering method. in addition  , we discuss the ground - state properties in the thermodynamic limit.
every automaton group naturally acts on the space @xmath0 of infinite sequences over some alphabet @xmath1. for every @xmath2 we consider the schreier graph @xmath3 of the action of the group on the orbit of @xmath4.   we prove that for a large class of automaton groups all schreier graphs @xmath5 have subexponential growth bounded above by @xmath6 with some constant @xmath7.   in particular, this holds for all groups generated by automata with polynomial activity growth ( in terms of s.  sidki ), confirming a conjecture of v.  nekrashevych.   we present applications to @xmath8-periodic graphs and hanoi graphs.   + * mathematics subject classification 2000 * : 20f65, 05c25, 20f69.   + * keywords * : automaton group, schreier graph, subexponential growth.
fast fourier transform ( fft ) of large number of samples requires huge hardware resources of field programmable gate arrays ( fpga ), which needs more area and power. in this paper  , we present an area efficient architecture of fft processor that reuses the butterfly elements several times.   the fft processor is simulated using vhdl and the results are validated on a virtex-6 fpga.   the proposed architecture outperforms the conventional architecture of a @xmath0-point fft processor in terms of area which is reduced by a factor of @xmath1 with negligible increase in processing time.   fft, fpga, resource optimization
in this paper, energy efficient power control for the uplink two - tier networks where a macrocell tier with a massive multiple - input multiple - output ( mimo ) base station is overlaid with a small cell tier is investigated. we propose a distributed energy efficient power control algorithm which allows each user in the two - tier network taking individual decisions to optimize its own energy efficiency ( ee ) for the multi - user and multi - cell scenario.   the distributed power control algorithm is implemented by decoupling the ee optimization problem into two steps. in the first step, we propose to assign the users on the same resource into the same group and each group can optimize its own ee, respectively. in the second step, multiple power control games based on evolutionary game theory ( egt ) are formulated for each group, which allows each user optimizing its own ee. in the egt - based power control games, each player selects a strategy giving a higher payoff than the average payoff, which can improve the fairness among the users.   the proposed algorithm has a linear complexity with respect to the number of subcarriers and the number of cells in comparison with the brute force approach which has an exponential complexity.   simulation results show the remarkable improvements in terms of fairness by using the proposed algorithm.
in this paper, we describe a new hydrodynamics code for 1d and 2d astrophysical simulations, bethe - hydro, that uses time - dependent, arbitrary, unstructured grids.   the core of the hydrodynamics algorithm is an arbitrary lagrangian - eulerian ( ale ) approach, in which the gradient and divergence operators are made compatible using the support - operator method.   we present 1d and 2d gravity solvers that are finite differenced using the support - operator technique, and the resulting system of linear equations are solved using the tridiagonal method for 1d simulations and an iterative multigrid - preconditioned conjugate - gradient method for 2d simulations.   rotational terms are included for 2d calculations using cylindrical coordinates.   we document an incompatibility between a subcell pressure algorithm to suppress hourglass motions and the subcell remapping algorithm and present a modified subcell pressure scheme that avoids this problem.   strengths of this code include a straightforward structure, enabling simple inclusion of additional physics packages, the ability to use a general equation of state, and most importantly, the ability to solve self - gravitating hydrodynamic flows on time - dependent, arbitrary grids. in what follows  , we describe in detail the numerical techniques employed and, with a large suite of tests, demonstrate that bethe - hydro finds accurate solutions with 2@xmath0-order convergence.
recent studies indicate that type ia supernovae ( sne ia ) consist of two groups  a `` prompt '' component whose rates are proportional to the host galaxy star formation rate, whose members have broader lightcurves and are intrinsically more luminous, and a `` delayed '' component whose members take several gyr to explode, have narrower lightcurves, and are intrinsically fainter. as cosmic star formation density increases with redshift, the prompt component should begin to dominate.   we use a two - component model to predict that the average lightcurve width should increase by 6% from @xmath0. using data from various searches we find an 8.1%@xmath12.7% increase in average lightcurve width for non - subluminous sne ia from @xmath2, corresponding to an increase in the average intrinsic luminosity of 12%. to test whether there is any bias after supernovae   are corrected for lightcurve shape we use published data to mimic the effect of population evolution and find no significant difference in the measured dark energy equation of state parameter, @xmath3.   however, future measurements of time - variable @xmath3 will require standardization of sn ia magnitudes to 2% up to @xmath4, and it is not yet possible to assess whether lightcurve shape correction works at this level of precision.   another concern at @xmath5 is the expected order of magnitude increase in the number of sne ia that can not be calibrated by current methods.
rna can be used as a high - density medium for data storage and transmission ; however, an important rna process   replication  is noisy.   this paper presents an error analysis for rna as a data transmission medium, analyzing how deletion errors increase in a collection of replicated dna strands over time.
we present new results on rr lyrae stars and anomalous cepheids in the draco dwarf spheroidal galaxy.   we have increased the number of double - mode rr lyrae stars and found three new anomalous cepheids. with period - magnitude and period - amplitude diagrams  , we discuss the oosterhoff classification of draco.   contradictory results were found in that draco appears to contain both oosterhoff i and ii type rr lyrae populations.
the lowest 37000 eigenvalues of the area operator in loop quantum gravity is calculated and studied numerically.   we obtain an asymptotical formula for the eigenvalues as a function of their sequential number.   the multiplicity of the lowest few hundred eigenvalues is also determined and the smoothed spectral density is calculated. the spectral density is presented for various number of vertices, edges and su(2 ) representations. a scaling form of spectral density is found, being a power law for one vertex, while following an exponential for several vertices.   the latter case is explained on the basis of the one vertex spectral density.
we investigate the properties in finite magnetic field of an extended anisotropic xxz spin-1/2 model on the kagom lattice, originally introduced by balents, fisher, and girvin [ phys.   rev.   b, * 65 *, 224412 ( 2002 ) ].   the magnetization curve displays plateaus at magnetization @xmath0 and @xmath1 when the anisotropy is large. using low - energy effective constrained models ( quantum loop and quantum dimer models )  , we discuss the nature of the plateau phases, found to be crystals that break discrete rotation and/or translation symmetries.   large - scale quantum monte - carlo simulations were carried out in particular for the @xmath0 plateau.   we first map out the phase diagram of the effective quantum loop model with an additional loop - loop interaction to find stripe order around the point relevant for the original model as well as a topological @xmath2 spin liquid.   the existence of a stripe crystalline phase is further evidenced by measuring both standard structure factor and entanglement entropy of the original microscopic model.
we report on the detection of radio emission from the accretion - powered x - ray millisecond pulsar sax j1808.43658, using the australia telescope compact array.   we detected a @xmath00.8  mjy source at the position of sax  j1808.43658 on 1998 april 27, approximately one day after the onset of a rapid decline in the x - ray flux ; no such source was seen on the previous day.   we consider this emission to be related to the radio emission from other x - ray binaries, and is most likely associated with an ejection of material from the system.   no radio emission was detected at later epochs, indicating that if sax  j1808.43658 is a radio pulsar during x - ray quiescence then its monochromatic luminosity must be less than @xmath1  mjy  kpc@xmath2.   = 10001
by using a simple relativistic model, we compute the glueball and gluelump spectra and relate these quantities, respectively, to the trace anomaly and polyakov loop in the adjoint representation of gluodynamics.   this spectroscopic description of thermodynamics is extended with the inclusion of quarks. the relation between the hadron resonance gas and the polyakov loop in the fundamental and higher representations   is addressed.   gluodynamics, qcd thermodynamics, glueballs, heavy quarks, chiral quark models, polyakov loop
trapped ions are pre - eminent candidates for building quantum information processors and quantum simulators.   to scale such systems to more than a few tens of ions it is important to tackle the observed high ion - heating rates and create scalable trap structures which can be simply and reliably produced. here, we report on cryogenically operated intrinsic - silicon ion traps which can be rapidly and easily fabricated using standard semiconductor technologies.   single @xmath0ca@xmath1 ions have been trapped and used to characterize the trap operation.   long ion lifetimes were observed with the traps exhibiting heating rates as low as @xmath2 0.33phonons / s at an ion - electrode distance of 230@xmath3 m.   these results open many new avenues to arrays of micro - fabricated ion traps.
we have obtained near - infrared images and spectra of three blue compact dwarf galaxies of intermediate sub - solar metallicity tol  35, tol  3 and um  462.   this work is part of a larger project aimed to study the star formation and the stellar populations of low metallicity galaxies in the near - infrared. in this frame   work galaxies of intermediate metallicity represent an important step in understanding the most extreme cases filling the gap between solar and very low metallicity galaxies.   we have observed hii region like spectra in all three galaxies ; in all cases the star formation episodes are only a few myr old.   consistently with a young age our spectra show no evidence for stellar absorption features typical of supergiants, nor of  emission typical of supernovae.   the k - band gas fraction ranges from 20 to 40 % showing that gas emission can significantly contaminate broadband near - infrared colors in young metal - poor starbursts.   we have detected molecular hydrogen in emission in all three objects.   all sources show bright knots superimposed on a lower surface brighness envelope.   the knots are identified with super star clusters ; six of them are present in um  462. in all galaxies   we detect the presence of an old stellar population.
the model of dna torsion dynamics supports soliton solutions, which are supposed to be of special interest for dna transcription. in the discussion of the model,   one usually adopts the approximation @xmath0, where @xmath1 is a parameter related to the equilibrium distance between bases in a watson - crick pair. here   we analyze the model without @xmath2.   the model still supports soliton solutions indexed by two winding numbers @xmath3 ; we discuss in detail the fundamental solitons, corresponding to winding numbers ( 1,0 ) and ( 0,1 ) respectively.
monte carlo(mc ) simulations produce evidence that annealed copolymers incorporating two interconverting monomers, p and h, adsorb as homopolymers with an effective adsorption energy per monomer, @xmath0, that depends on the ph equilibrium constants in the bulk and at the surface.   the cross - over exponent, @xmath1 is unmodified.   the mc results on the overall ph ratio, the ph ratio at the surface and in the bulk as well as the number of adsorbed monomers are in quantitative agreement with this hypothesis and the theoretically derived @xmath0.   the evidence suggests that the form of surface potential does not affect @xmath2 but does influence the ph equilibrium.
we introduce a semi - classical wavefunction ( scwf ) model for strong - field physics and attosecond science. when applied to high harmonic generation ( hhg ), this formalism allows one to show that the natural time - domain separation of the contribution of ionization, propagation and recollisions to the hhg process leads to a frequency - domain factorization of the harmonic yield into these same contributions, for any choice of atomic or molecular potential.   we first derive the factorization from the natural expression of the dipole signal in the temporal domain by using a reference system, as in the quantitative rescattering ( qrs ) formalism [ j.  phys.   b.  * 43 *, 122001 ( 2010 ) ].   alternatively, we show how the trajectory component of the scwf can be used to express the factorization, which also allows one to attribute individual contributions to the spectrum to the underlying trajectories.
it is shown that one can obtain quantitatively accurate values for the superconducting critical temperature within a hamiltonian framework.   this is possible if one uses a renormalized hamiltonian that contains an attractive electron   electron interaction and renormalized single particle energies.   it can be obtained by similarity renormalization or using flow equations for hamiltonians.   we calculate the critical temperature as a function of the coupling using the standard bcs  theory. for small coupling   we rederive the mcmillan formula for @xmath0.   we compare our results with eliashberg theory and with experimental data from various materials.   the theoretical results agree with the experimental data within 10%.   renormalization theory of hamiltonians provides a promising way to investigate electron   phonon interactions in strongly correlated systems.   euromacr
in this note, we reconcile two approaches that have been used to construct stringy multiplications.   the pushing forward after pulling back that has been used to give a global stringy extension of the functors @xmath0@xcite, and the pulling back after having pushed forward, which we have previously used in our ( re)-construction program for @xmath1frobenius algebras, notably in considerations of singularities with symmetries and for symmetric products.   a similar approach was also used by @xcite in their considerations of the chen   ruan product in a derham setting for abelian orbifolds.   we show that the pull  push formalism has a solution by the push   pull equations in two situations.   the first is a derham formalism with thom push  forward maps and the second is the setting of cyclic twisted sectors, which was at the heart of the ( re)-construction program.   we go on to do formal calculations using fractional euler classes which allows us to formally treat all the stringy multiplications mentioned above in the general setting.   the upshot is the formal trivialization of the co  cycles of the reconstruction program using the presentation of the obstruction bundle of @xcite.
motivated by the insb nanowire superconductor system, we investigate a system where one - dimensional topological superconductors are placed in parallel.   it would be simulated well by a ladder of the kitaev chains.   the system undergoes multiple topological phase transitions, where the number of majorana fermions changes as a function of the interchain superconducting pairings.   we analytically determine the topological phase diagram by explicitly calculating the topological number and the band structure.   they show even - odd effects with respect to the number of legs of the ladder.   when the relative phase between the inter- and intrachain superconducting pairings is 0 or @xmath0, the system belongs to the class bdi characterized by the @xmath1 index, and otherwise it belongs to the class d characterized by the @xmath2 index.   this topological class change would be caused by applying the josephson current or an external magnetic field, and could be observed by measuring the zero - bias differential conductance.
this paper defines a class of labeled stratified order structures that characterizes exactly the notion of _ _ com__bined _ traces _   ( i.e., _ comtraces _ ) proposed by janicki and koutny in 1995.   our main technical contributions are the representation theorems showing that comtrace quotient monoid, _ combined dependency graph _   ( kleijn and koutny 2008 ) and our labeled stratified order structure characterization are three different and yet equivalent ways to represent comtraces.   + * keywords.   * causality theory of concurrency, combined traces monoids, step sequences, stratified order structures, label - preserving isomorphism.
hypervelocity stars have been recently discovered in the outskirts of galaxies, such as the unbound star in the milky way halo, or the three anomalously fast intracluster planetary nebulae ( icpne ) in the virgo cluster.   these may have been ejected by close 3-body interactions with a binary supermassive black hole ( smbbh ), where a star which passes within the semimajor axis of the smbbh can receive enough energy to eject it from the system.   stars ejected by smbbhs may form a significant sub - population with very different kinematics and mean metallicity than the bulk of the intracluster stars.   the number, kinematics, and orientation of the ejected stars may constrain the mass ratio, semimajor axis, and even the orbital plane of the smbbh.   we investigate the evolution of the ejected debris from a smbbh within a clumpy and time - dependent cluster potential using a high resolution, self - consistent cosmological n - body simulation of a galaxy cluster.   we show that the predicted number and kinematic signature of the fast virgo icpne is consistent with 3-body scattering by a smbbh with a mass ratio @xmath0 at the center of m87.
in the mapping of the local ism it is of some interest to know where the first indications of the boundary of the local bubble can be measured.   the hipparcos distances combined to @xmath0 photometry and some sort of spectral classification permit mapping of the spatial extinction distribution.   photometry is available for almost the complete hipparcos sample and michigan classification is available for brighter stars south of @xmath1 = + 5 ( 1900 ). for the northern and fainter stars spectral types, e.g. the hd types,   are given but a luminosity class is often missing.   the @xmath0 photometry and the parallax do, however, permit a dwarf / giant separation due to the value of the slope of the reddening vector compared to the gradient of the main sequence in a color magnitude diagram, in the form : @xmath0 @xmath2 @xmath3 = @xmath4, together with the rather shallow extinction present in the hipparcos sample.   we present the distribution of median @xmath5 for stars with hipparcos 2 distances less than 55 pc. the northern part of the first and second quadrant has most extinction, up to @xmath60.2 mag and the southern part of the third and fourth quadrant the slightest extinction, @xmath60.05 mag.   the boundary of the extinction minimum appears rather coherent on an angular resolution of a few degrees        local bubble   interstellar extinction   hipparcos distance extinction pairs
we consider the problem of a robot learning the mechanical properties of objects through physical interaction with the object, and introduce a practical, data - efficient approach for identifying the motion models of these objects.   the proposed method utilizes a physics engine, where the robot seeks to identify the inertial and friction parameters of the object by simulating its motion under different values of the parameters and identifying those that result in a simulation which matches the observed real motions.   the problem is solved in a bayesian optimization framework.   the same framework is used for both identifying the model of an object online and searching for a policy that would minimize a given cost function according to the identified model.   experimental results both in simulation and using a real robot indicate that the proposed method outperforms state - of - the - art model - free reinforcement learning approaches.
we experimentally analyze a bessel beam produced with a conical mirror, paying particular attention to its superluminal and diffraction - free properties.   we spatially characterized the beam in the radial and on - axis dimensions, and verified that the central peak does not spread over a propagation distance of @xmath0 @xmath1.   in addition, we measured the superluminal phase and group velocities of the beam in free space.   both spatial and temporal measurements show good agreement with the theoretical predictions.
we present a comprehensive update of the bounds on r - parity violating supersymmetric couplings from lepton - flavour- and lepton - number - violating decay processes.   we consider @xmath0 and @xmath1 decays as well as leptonic and semi - leptonic decays of mesons.   we present several new bounds resulting from @xmath0, @xmath2 and kaon decays and correct some results in the literature concerning @xmath3-meson decays.
the ratios of off - diagonal and diagonal susceptibilities of conserved charges are studied using a hadron resonance gas ( hrg ) model with an emphasis towards providing a proper baseline for comparison to the corresponding future experimental measurements.   we have studied the effect of kinematic acceptances, transverse momentum ( @xmath0 ) and pseudorapidity ( @xmath1 ), and different charged states on the ratios of the calculated susceptibilities.   we find that the effect of @xmath0 and @xmath1 acceptance on the ratio of the susceptibilities are small relative to their dependence on the beam energy or the charged states of the used particles.   we also present a hrg based calculation for various combinations of cumulant ratios of protons and pions, recently proposed as robust observables ( with no theoretical uncertainties ) for critical point search in the experiments. these results which increase as a function of collision energy will provide a better baseline for non - critical point physics compared to poisson expectation.
using the data from the pca and hexte on board the rxte satellite, we investigate the evolution of the 3 - 200 kev spectra of the peculiar low mass x - ray binary ( lmxb ) cir  x-1 along the branches on its hardness - intensity diagram ( hid ) from the vertical horizontal branch ( vhb ), through the horizontal horizontal branch ( hhb ) and normal branch ( nb ), to the flaring branch ( fb ).   we detect a power - law hard component in the spectra. it is found that the derived photon indices ( @xmath0 ) of the power - law hard component are correlated with the position on the hid.   the power - law component dominates the x - ray emission of cir  x-1 in the energy band higher than @xmath1 kev.   the fluxes of the power - law component are compared with those of the bremsstrahlung component in the spectra. a possible origin of the power - law hard component is discussed.
we have found that, in the intensity - dependent jaynes - cummings model, a field initially prepared in a statistical mixture of two coherent states, @xmath0 and @xmath1, evolves toward a pure state.   we have also shown that an even - coherent state turns    periodically a into rotated odd - coherent state during the evolution.
the baryon dirac form factor is computed at one - loop order in large-@xmath0 baryon chiral perturbation theory, where @xmath0 is the number of color charges.   loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet - octet mass difference are accounted for.   there are large-@xmath0 cancellations between different one - loop graphs as a consequence of the large-@xmath0 spin - flavor symmetry of qcd baryons. as a byproduct  , the mean - square charge radius is also computed through a detailed numerical analysis.   the predictions of large-@xmath0 baryon chiral perturbation theory are in very good agreement both with the expectations from the @xmath1 expansion and with the experimental data.
by using the drone - fermion representation and the schwinger - keldysh approach, we calculate the current noise and the charge noise for a single - electron transistor in the non - equilibrium state in the presence of large quantum fluctuation of island charge.   our result interpolates between those of the orthodox `` theory and the co - tunneling theory ''.   we find the following effects which are not treated by previous theories : ( i ) at zero temperature @xmath0 and at finite applied bias voltage @xmath1, where @xmath2 is the kondo temperature ``, we find the fano factor is suppressed more than the suppression caused by coulomb correlation both in the coulomb blockade regime and in the sequential tunneling regime.   ( ii ) for @xmath3, the current noise in the presence of large charge fluctuation is modified and deviates from the prediction of the orthodox theory. however, the fano factor coincides with that of the orthodox theory and is proportional to the temperature.   ( iii ) for @xmath4, the charge noise is suppressed due to the renormalization of system parameters caused by quantum fluctuation of charge.   we interpret it in terms of the modification of the unit '' for island charge.
protecting quantum correlation from decoherence is one of the crucial issues in quantum information processing.   it has been commonly recognized that any initial quantum correlation of a composite system diminishes asymptotically or abruptly to zero under local markovian decoherence. here   we show that, contrary to this recognition, a noticeable gaussian quantum discord of a continuous - variable bipartite system can be frozen in the steady state in the non - markovian dynamics if each of the subsystems forms a localized mode with its local reservoir.   the condition for this frozen quantum discord can be reached by appropriately engineering the structure of the reservoirs.   the possible realization of our results in a coupled cavity array system formed by a photonic crystal is proposed.
we investigate growing networks based on barabsi and albert s algorithm for generating scale - free networks, but with edges sensitive to overload breakdown.   the load is defined through edge betweenness centrality.   we focus on the situation where the average number of connections per vertex is, as the number of vertices, linearly increasing in time. after an initial stage of growth  , the network undergoes avalanching breakdowns to a fragmented state from which it never recovers.   this breakdown is much less violent if the growth is by random rather than preferential attachment ( as defines the barabsi and albert model ).   we briefly discuss the case where the average number of connections per vertex is constant. in this case   no breakdown avalanches occur.   implications to the growth of real - world communication networks are discussed.
we investigate structure and kinematics of the second generation of stars ( sg ) formed from gaseous ejecta of the first generation of stars ( fg ) in forming globular clusters ( gcs ).   we consider that sg can be formed from gaseous ejecta from agb stars of fg with the initial total mass of @xmath0 to explain the present masses of the galactic gcs.   our 3d hydrodynamical simulations with star formation show that sg formed in the central regions of fg can have a significant amount of rotation ( @xmath1 @xmath2 ).   the rotational amplitude of sg can depend strongly on the initial kinematics of fg.   we thus propose that some gcs composed of fg and sg had a significant amount of rotation when they were formed.   we also suggest that although later long - term ( @xmath3 gyr ) dynamical evolution of stars can smooth out the initial structural and kinematical differences between fg and sg to a large extent, initial flattened structures and rotational kinematics of sg can be imprinted on shapes and internal rotation of the present gcs.   we discuss these results in terms of internal rotation observed in the galactic gcs.
we investigate matter effects on highly relativistic neutrinos. the self - energy of neutrinos is determined in an electron or neutrino background taking into account resonance and finite width effects of the gauge bosons.   we find minor changes compared to the formerly used formula for the propagator function and large deviations of the effective width from the decay width of the gauge bosons considering higher moments of the electron or neutrino distribution function.
the distinction between the real positions of moving objects in a single reference frame and the apparent positions of objects at rest in one inertial frame and viewed from another, as predicted by the space - time lorentz transformations, is discussed.   it is found that in the rockets - and - string paradox the string remains unstressed and does not break and that the pole in the barn - and - pole paradox never actually fits into the barn.   the close relationship of the lorentz - fitzgerald contraction and the relativity of simultaneity of special relativity is pointed out and an associated paradox, in which causality is apparently violated, is noted.   24.5 cm -5pt -5pt -50pt addtoresetequationsection    * j.h.field *     dpartement de physique nuclaire et corpusculaire universit de genve.   24, quai ernest - ansermet ch-1211 genve 4.   e - mail : john.field@cern.ch
we investigate by numerical simulations the behavior of the power dissipated in a resistive load capacitively coupled to a josephson flux flow oscillator and compare the results to those obtained for a d.c.   coupled purely resistive load.   assuming realistic values for the parameters @xmath0 and @xmath1, both in the high- and in the low-@xmath2 case the power is large enough to allow the operation of such a device in applications.
we discuss the feasibility of seeing a higgs boson which decays to four partons through a pair of ( pseudo-)scalars at the lhc.   we restrict our search to higgs bosons produced in association with a @xmath0 boson at high transverse momentum.   we argue that subjet analysis techniques are a good discriminant between such events and @xmath0 plus jets and @xmath1 production. for light scalar masses ( below @xmath2 gev )  , we find evidence that a flavor - independent search for such a non - standard higgs boson is plausible with @xmath3 fb@xmath4 of data, while a higgs decaying to heavier scalars is only likely to be visible in models where scalar decays to @xmath5 quarks dominate.   -1.5 cm
tangential and radial angles of muons in eas, a useful concept in investigation of the muon production height, can be used also for the investigation of the muon momenta.   a parameter @xmath0, being a combination of tangential and radial angles, is introduced and its possible applications in investigation of muons in showers are presented.
we prove that every computably enumerable ( c.e. )   random real is provable in peano arithmetic ( pa ) to be c.e.  random.   a major step in the proof is to show that the theorem stating that `` a real is c.e.  and   random iff it is the halting probability of a universal prefix - free turing machine '' can be proven in pa.   our proof, which is simpler than the standard one, can also be used for the original theorem.   our positive result can be contrasted with the case of computable functions, where not every computable function is provably computable in pa, or even more interestingly, with the fact that almost all random finite strings are not provably random in pa.   we also prove two negative results : a ) there exists a universal machine whose universality can not be proved in pa, b ) there exists a universal machine @xmath0 such that, based on @xmath0, pa can not prove the randomness of its halting probability.   the paper also includes a sharper form of the kraft - chaitin theorem, as well as a formal proof of this theorem written with the proof assistant isabelle.
we study the effects that ripples induce on the electrical and magnetic properties of graphene.   the variation of the interatomic distance created by the ripples translates in a modulation of the hopping parameter between carbon atoms.   a tight binding hamiltonian including a hubbard interaction term is solved self consistently for ripples with different amplitudes and periods.   we find that, for values of the hubbard interaction @xmath0 above a critical value @xmath1, the system displays a superposition of local ferromagnetic and antiferromagnetic ordered states.   nonetheless the global ferromagnetic order parameter is zero.   the @xmath1 depends only on the product of the period and hopping amplitude modulation.   when the hubbard interaction is close to the critical value of the antiferromagnetic transition in pristine graphene, the antiferromagnetic order parameter becomes much larger than the ferromagnetic one, being the ground state similar to that of flat graphene.
the purpose of the present study is to compare the predictions of different models of star formation rate ( sfr ) history in the universe with the upper limit of super kamiokande for the neutrino background. to this aim   we have calculated the expected neutrino density for the most popular models of sfr history, hogg et al.  , glazebrook et al., cole et al., yuksel et al.  , hernquist et al. and   kaplinghat et al.   different from previous studies we have used the @xmath0cdm model with @xmath1.   we have assumed that the detector used for the detection the neutrino flux is superk and also we have assumed that the electron neutrinos produced in the supernovae oscillate equally to the three standard model flavors. by these assumptions   all models stay below the upper limit of superk on the event rate and the detection of the supernova relic neutrino background ( srnb ) remains undetected.   future neutrino detectors such as km3net will be able to detect the srnb and distinguish between the models of the sfr history.
we combine the  extended source catalogue and the 2df galaxy redshift survey to produce an infrared - selected galaxy catalogue with measured redshifts.   we use this extensive dataset to estimate the galaxy luminosity functions in the j- and -bands.   the luminosity functions are fairly well fit by schechter functions with parameters @xmath0, @xmath1, @xmath2 mpc@xmath3 in the j - band and @xmath4, @xmath5, @xmath6 mpc@xmath3 in the -band (  kron magnitudes ).   these parameters are derived assuming a cosmological model with @xmath7 and @xmath8. with datasets of this size,   systematic rather than random errors are the dominant source of uncertainty in the determination of the luminosity function.   we carry out a careful investigation of possible systematic effects in our data.   the surface brightness distribution of the sample shows no evidence that significant numbers of low surface brightness or compact galaxies are missed by the survey.   we estimate the present - day distributions of @xmath9  and j@xmath9  colours as a function of absolute magnitude and use models of the galaxy stellar populations, constrained by the observed optical and infrared colours, to infer the galaxy stellar mass function.   integrated over all galaxy masses, this yields a total mass fraction in stars ( in units of the critical mass density ) of @xmath10 for a kennicutt imf and @xmath11 for a salpeter imf.   these values are consistent with those inferred from observational estimates of the total star formation history of the universe provided that dust extinction corrections are modest.   galaxies : luminosity function estimators   ''' ''
we report on electronic transport calculations for self - assembled mono - layers ( sam ) of 1,4-phenylene diisocyanide on au(111 ) contacts.   experimentally one observes more structure ( i.e  peaks ) within the measured conductance curve for this molecule with two cyanide end - groups, compared to measurements with molecules having thiol end - groups.   the calculations are performed on the semi - empiric extended hckel level using elastic scattering quantum chemistry ( esqc ) and we investigate three possible explanations for the experimental findings. comparing the experimental and theoretical data, we are able to rule out all but one of the scenarios. the observed additional peaks are found to be only reproduced by a mono - layer with additional molecules perturbing the periodicity.   it is conjectured that the weaker coupling to au of cyanide end - groups compared to thiol end - groups might be responsible for such perturbations.
cross sections for production of @xmath0he, @xmath0li, @xmath1li, and @xmath1be in the @xmath2 reaction were measured at bombarding energies of 159.3, 279.6, and @xmath3mev, and are found to decrease rapidly with increasing energy.   these cross sections are essential for the calculation of the rate of nucleosynthesis of the lithium isotopes in the cosmic rays and thereby play a key role in our understanding of the synthesis of li, be, and b. the results for @xmath0li differ significantly from the tabulated values commonly used in cosmic - ray production calculations and lead to lower production of @xmath0li.
we present an estimate of the bolometric x - ray luminosity - velocity dispersion ( @xmath0 ) relation measured from a new, large and homogeneous sample of 171 low redshift, x - ray selected galaxy clusters  . the linear fitting of @xmath1 gives @xmath2 erg s@xmath3 h@xmath4.   furthermore, a study of 54 clusters, for which the x - ray temperature of the intracluster medium t is available, allows us to explore two other scaling relations, @xmath5 and @xmath6. from this sample   we obtain @xmath7 and @xmath8, which are fully consistent with the above result for the @xmath9-@xmath10.   the slopes of @xmath5 and @xmath6 are incompatible with the values predicted by self - similarity ( @xmath11 ), thus suggesting the presence of non - gravitational energy sources heating up the intracluster medium, in addition to the gravitational collapse, in the early stages of cluster formation. on the other hand,   the result on @xmath1 supports the self - similar model.       cosmology : observations  galaxies : clusters : general  galaxies : fundamental parameters
we have investigated the fluctuations and the higher order susceptibilities of quark number, isospin number, electric charge and strangeness at vanishing chemical potential for 2 + 1 flavor polyakov loop extended nambu  jona - lasinio model.   the calculations are performed for the bound effective potential in the quark sector requiring up to eight quark interaction terms.   these have been contrasted to the lattice results which currently have somewhat heavier quarks in the light flavor sector.   the results show sufficient qualitative agreement. for comparison we also present the results obtained with the conventional effective potential containing upto six quark interaction terms.
this paper describes a model for nonlinear acoustic wave propagation through absorbing and weakly dispersive media, and its numerical solution by means of finite differences in time domain method ( fdtd ).   the attenuation is based on multiple relaxation processes, and provides frequency dependent absorption and dispersion without using computational expensive convolutional operators. in this way, by using an optimization algorithm the coefficients for the relaxation processes can be obtained in order to fit a frequency power law that agrees the experimentally measured attenuation data for heterogeneous media over the typical frequency range for ultrasound medical applications.   our results show that two relaxation processes are enough to fit attenuation data for most soft tissues in this frequency range including the fundamental and the first ten harmonics.   furthermore, this model can fit experimental attenuation data that do not follow exactly a frequency power law over the frequency range of interest.   the main advantage of the proposed method is that only one auxiliary field per relaxation process is needed, which implies less computational resources compared with time - domain fractional derivatives solvers based on convolutional operators.
we construct higher order rogue wave solutions and breather profiles for the quasi - one - dimensional gross - pitaevskii equation with a time - dependent interatomic interaction and external trap through the similarity transformation technique.   we consider three different forms of traps, namely ( i ) time - independent expulsive trap, ( ii ) time - dependent monotonous trap and ( iii ) time - dependent periodic trap.   our results show that when we change a parameter appearing in the time - independent or time - dependent trap the second and third - order rogue waves transform into the first - order like rogue waves.   we also analyze the density profiles of breather solutions. here   also we show that the shapes of the breathers change when we tune the strength of trap parameter.   our results may help to manage rogue waves experimentally in a bec system.
we carry out ray tracing through five high resolution simulations of a galaxy cluster to study how its ability to produce giant gravitationally lensed arcs is influenced by the collision cross - section of its dark matter. in three cases typical dark matter particles in the cluster core   undergo between 1 and 100 collisions per hubble time ; two more explore the long ( `` collisionless '' ) and short ( `` fluid '' ) mean free path limits.   we study the size and shape distributions of arcs and compute the cross - section for producing `` extreme '' arcs of various sizes.   even a few collisions per particle modify the core structure enough to destroy the cluster s ability to produce long, thin arcs. for larger collision frequencies the cluster must be scaled up to unrealistically large masses before it regains the ability to produce giant arcs.   none of our models with self - interacting dark matter ( except the `` fluid '' limit ) is able to produce radial arcs ; even the case with the smallest scattering cross - section must be scaled to the upper limit of observed cluster masses before it produces radial arcs.   apparently the elastic collision cross - section of dark matter in clusters must be very small, below 0.1 @xmath0g@xmath1, to be compatible with the observed ability of clusters to produce both radial arcs and giant arcs.   dark matter  gravitational lensing   cosmology : theory  galaxies : clusters
we study in detail the quasinormal modes of linear gravitational perturbations of plane - symmetric anti - de sitter black holes.   the wave equations are obtained by means of the newman - penrose formalism and the chandrasekhar transformation theory.   we show that oscillatory modes decay exponentially with time such that these black holes are stable against gravitational perturbations.   our numerical results show that in the large ( small ) black hole regime the frequencies of the ordinary quasinormal modes are proportional to the horizon radius @xmath0 ( wave number @xmath1 ).   the frequency of the purely damped mode is very close to the algebraically special frequency in the small horizon limit, and goes as @xmath2 in the opposite limit.   this result is confirmed by an analytical method based on the power series expansion of the frequency in terms of the horizon radius.   the same procedure applied to the schwarzschild anti - de sitter spacetime proves that the purely damped frequency goes as @xmath3, where @xmath4 is the quantum number characterizing the angular distribution. finally, we study the limit of high overtones and find that the frequencies become evenly spaced in this regime.   the spacing of the frequency per unit horizon radius seems to be a universal quantity, in the sense that it is independent of the wave number, perturbation parity and black hole size.
the usage of x - ray free electron laser ( xfel ) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation.   hence a wide radiation bandwidth will be useful in order to obtain and to index a larger number of bragg peaks used for determination of the crystal orientation.   considering the baseline configuration of the european xfel in hamburg, and based on beam dynamics simulations, we demonstrate here that the usage of corrugated structures allows for a considerable increase in radiation bandwidth.   data collection with a 3% bandwidth, a few microjoule radiation pulse energy, a few femtosecond pulse duration, and a photon energy of 5.4 kev is possible.    for this study   we have developed an analytical _ modal _ representation of the short - range wake function of the flat corrugated structures for arbitrary offsets of the source and the witness particles.   _ keywords _ : wakefields, impedance, corrugated structure, longitudinal phase space control, free electron laser, bandwidth.   desy 16 - 138 + july 2016
the upper limit on the energy density of a stochastic gravitational wave ( gw ) background obtained from the two - year science run ( s5 ) of the laser interferometer gravitational - wave observatory ( ligo ) is used to constrain the average gw production of core collapse supernovae ( ccsne ).   we assume that the ccsne rate tracks the star formation history of the universe and show that the stochastic background energy density depends only weakly on the assumed average source spectrum. using the ccsne rate for @xmath0,   we scale the generic source spectrum to obtain an observation - based upper limit on the average gw emission.   we show that the mean energy emitted in gws can be constrained within @xmath1 depending on the average source spectrum. while these results are higher than the total available gravitational energy in a core collapse event, second and third generation gw detectors will enable tighter constraints to be set on the gw emission from such systems.
electron beam induced current ( ebic ) is a powerful characterization technique which offers the high spatial resolution needed to study polycrystalline solar cells.   current models of ebic assume that excitations in the @xmath0-@xmath1 junction depletion region result in perfect charge collection efficiency.   however we find that in cdte and si samples prepared by focused ion beam ( fib ) milling, there is a reduced and nonuniform ebic lineshape for excitations in the depletion region.   motivated by this, we present a model of the ebic response for excitations in the depletion region which includes the effects of surface recombination from both charge - neutral and charged surfaces. for neutral surfaces we present a simple analytical formula which describes the numerical data well, while the charged surface response depends qualitatively on the location of the surface fermi level relative to the bulk fermi level.   we find the experimental data on fib - prepared si solar cells is most consistent with a charged surface, and discuss the implications for ebic experiments on polycrystalline materials.
we review several aspects of clusters of galaxies and their application to cosmology.   we present first results of numerical simulations of the dynamics of the intra - cluster gas and of different interaction processes between cluster galaxies and the intra - cluster gas.   in particular metallicity maps are very useful to determine the importance of the different interaction processes.   also mass determination methods and possible sources for uncertainties in the measurements are shown.
diffuse emission in the mid - infrared shows a wealth of structure, that lends itself to high - resolution structure analysis of the interstellar gas. a large part of the emission comes from polycyclic aromatic hydrocarbons, excited by nearby ultra - violet sources. can the observed diffuse emission structure be interpreted as column density structure?   we discuss this question with the help of a set of model molecular clouds bathed in the radiation field of a nearby o - star.   the correlation strength between column density and `` observed '' flux density strongly depends on the absolute volume density range in the region.   shadowing and irradiation effects may completely alter the appearance of an object.   irradiation introduces additional small - scale structure and it can generate structures resembling shells around hii - regions in objects that do not possess any shell - like structures whatsoever.   nevertheless, structural information about the underlying interstellar medium can be retrieved. in the more diffuse regime ( @xmath0@xmath1 )  , flux density maps may be used to trace the 3d density structure of the cloud via density gradients.   thus, while caution definitely is in order, mid - infrared surveys such as glimpse will provide quantitative insight into the turbulent structure of the interstellar medium.
the superconducting ( sc ) high intensity and energy ( hie ) isolde linac will replace most of the existing accelerating infrastructure of the radioactive ion beam experiment ( rex ) at cern, however, the 101.28 mhz rfq and 5 mv ih cavity will remain in the role of injector for the upgrade, boosting the beam up to an energy of 1.2 mev / u.   we present the results of a beam dynamics investigation of the injector focused most critically on matching the longitudinal beam parameters from the rfq to the sc machine, which is complicated largely by the ih cavity employing a combined zero degree ( konus ) beam dynamics design,  @xcite.   the longitudinal beam parameters at the rfq are reconstructed from measurement using the three gradient method and combined with beam dynamics measurements and simulations of the ih structure to design the matching section for the sc linac.
an attempt at understanding the downward overshooting in the convective envelopes of the post - main - sequence stars has been made on the basis of three - dimensional large eddy simulations, using artificially modified opal opacity and taking into account radiation and ionization in the equation of state.   two types of stars, an intermediate mass star and a massive star were considered. to avoid the long thermal relaxation time of the intermediate mass star  , we increased the stellar energy flux artificially while trying to maintain a structure close to the one given by one - dimensional stellar model.   a parametric study of the flux factor was performed. for the massive star,   no such manner was necessary.   numerical results were analyzed when the system reached the statistical steady state.   it was shown that the penetration distance in pressure scale heights is of the order of unit.   the scaling relations among the penetration distance, input flux and vertical velocity fluctuations studied by singh et al.   ( 1998 ) were checked.   the anisotropy of the turbulent convection and the diffusion models of third order moments representing the non - local transports were also investigated.   these models are dramatically affected by the velocity fields and no universal constant parameters seem to exist.   the limitation of the numerical results was discussed as well.       convection  hydrodynamics  turbulence  methods : numerical  stars : interiors.
and to a direct numerical simulation ( dns ) of the navier - stokes equations.   we derive the krmn - howarth equation for both the clark@xmath0 and leray@xmath0 models.   we confirm one of two possible scalings resulting from this equation for clark@xmath0 as well as its associated @xmath1 energy spectrum.   clark@xmath0 reproduces the large - scale energy spectrum and intermittency properties of the dns. for the leray@xmath0 model,   increasing the filter width, @xmath2, decreases the nonlinearity and, hence, the effective reynolds number is substantially decreased.   therefore even for the smallest value of @xmath2 studied leray@xmath0 was inadequate as a sgs model.   the lans@xmath0 energy spectrum @xmath3, consistent with its so - called `` rigid bodies, '' precludes a reproduction of the large - scale energy spectrum of the dns.   we find, however, that this same feature reduces its intermittency compared to clark@xmath0 ( which shares a similar krmn - howarth equation ).   clark@xmath0 is found to be the best approximation for reproducing the total dissipation rate and the energy spectrum at scales larger than @xmath2, whereas high - order intermittency properties for larger values of @xmath2 are best reproduced by lans@xmath0.
we consider meson radiative decays within the framework of @xmath0 gauge symmetry.   this approach is based on the linear sigma - model extended by the gauge and quark - meson interactions.   physical content and parameters of the model are discussed.   theoretical predictions for some radiative decays of vector mesons are in a good agreement with the experimental data.
real - time monitoring and responses to emerging public health threats rely on the availability of timely surveillance data. during the early stages of an epidemic, the ready availability of _ line lists _ with detailed tabular information about laboratory - confirmed cases can assist epidemiologists in making reliable inferences and forecasts.   such inferences are crucial to understand the epidemiology of a specific disease early enough to stop or control the outbreak  . however, construction of such line lists requires considerable human supervision and therefore, difficult to generate in real - time. in this paper  , we motivate * guided deep list *, the first tool for building automated line lists ( in near real - time ) from open source reports of emerging disease outbreaks. specifically, we focus on deriving epidemiological characteristics of an emerging disease and the affected population from reports of illness. *   guided deep list * uses distributed vector representations ( ala word2vec ) to discover a set of indicators for each line list feature.   this discovery of indicators is followed by the use of dependency parsing based techniques for final extraction in tabular form.   we evaluate the performance of * guided deep list * against a human annotated line list provided by healthmap corresponding to mers outbreaks in saudi arabia.   we demonstrate that * guided deep list * extracts line list features with increased accuracy compared to a baseline method.   we further show how these automatically extracted line list features can be used for making epidemiological inferences, such as inferring demographics and symptoms - to - hospitalization period of affected individuals.
recently atlas reported a @xmath0 excess in the stop search with @xmath1 channel.   we try to interpret the signal by a light stop pair production in the mssm.   we find : ( 1 ) simple models where stop decays into a higgsino or a bino are not favored.   ( 2 ) an extension of them can explain the data at @xmath2 level without conflicting with the other search channels.   a surviving possibility includes a light stop and a light higgsino, which is expected in a natural susy scenario.
directed and elliptic flow are reported for charged pions and protons as a function of transverse momentum, rapidity, and centrality in 40 and 158 agev pb + pb collisions.   the standard method of correlating particles with an event plane is used.   the directed flow of protons is small and shows little variation near to midrapidity, but rises fast towards projectile rapidity in the 40  agev data. for most peripheral collisions the flat region becomes negative resulting in @xmath0 changing sign three times.   elliptic flow does nt seem to change very much from 40  agev to 158  agev.   the difference is smaller than anticipated from the overall energy dependence from ags to rhic.
we propose a general numerical approach that can be used to study the invasion fitness of a mutant in evolutionary models and to determine evolutionary singular strategies when the competitive exclusion principle holds.   we illustrate this method with a mass - structured individual - based chemostat model.   we assume that the mutations are rare and that the resident population is large, in which case the mutant population can be viewed, on a short time scale, as evolving in a constant environment.   both deterministic and stochastic models can be proposed to describe such a problem.   we exploit a previously derived mathematical relationship between these models to derive a general method for analyzing the invasion fitness of stochastic models.   our method is based on a deterministic reduced model for which it is straightforward to determine the feasibility of invasion and the convergence - stable evolutionary singular strategy.    ] keywords : + + + + + + + + +    adaptive dynamics, invasion fitness, chemostat, evolutionary singular strategy, growth - fragmentation model, individual - based model, survival probability, eigenvalue.    ] mathematics subject classification ( msc2010 ) : + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +    92d15, 92d25, 35q92, 45c05.
gravitational wave detectors from the advanced generation onwards are expected to be limited in sensitivity by thermal noise of the optics, making the reduction of this noise a key factor in the success of such detectors. a proposed method for reducing   the impact of this noise is to use higher - order laguerre - gauss ( lg ) modes for the readout beam, as opposed to the currently used fundamental mode.   we present here a synopsis of the research program undertaken by the university of birmingham into the suitability of lg mode technology for future gravitational wave detectors.   this will cover our previous and current work on this topic, from initial simulations and table - top lg mode experiments up to implementation in a prototype scale suspended cavity and high - power laser bench.
we present a review and discussions on characterizations and quantifications of macroscopic quantum states as well as their implementations and applications in optical systems. we compare and criticize different measures proposed to define and quantify macroscopic quantum superpositions and extend such comparisons to several types of optical quantum states actively considered for experimental implementations within recent research topics.
the parity - non - conserving ( pnc ) asymmetry in @xmath0 at thermal energies has recently been calculated using effective field - theory methods. a comparison of this calculation with much more elaborate calculations performed in the 70 s is made.   this allows one to assess the validity of this new approach as presently used.   it is found to overshoot the almost exact calculations by a factor close to 2 for the contribution involving the @xmath1 component of both the initial and final states.   this is much larger than anticipated by the authors.   this discrepancy is analyzed and found to originate from the over - simplified description of the deuteron and capture states which underlies the new approach.   the claim that earlier determinations of the sign would be in error is also examined.   it is found that the sign discrepancy is most probably due, instead, to the fact that the pion - nucleon interaction referred to by the authors corresponds to a parity - non - conserving potential with a sign opposite to what is currently used.   some estimates and constraints relative to the pnc @xmath2nn coupling, @xmath3, which the above asymmetry is dependent on, are reviewed.   further details are given in an appendix.
the magnetization dynamics of spin torque oscillator ( sto ) consisting of a perpendicularly magnetized free layer and an in - plane magnetized pinned layer was studied by solving the landau - lifshitz - gilbert equation.   we derived the analytical formula of the relation between the current and the oscillation frequency of the sto by analyzing the energy balance between the work done by the spin torque and the energy dissipation due to the damping.   we also found that the field - like torque breaks the energy balance, and change the oscillation frequency.   spintronics, spin torque oscillator, perpendicularly magnetized free layer, the llg equation
multipartite quantum correlations are important resources for the development of quantum information and computation protocols.   however, the resourcefulness of multipartite quantum correlations in practical settings is limited by its fragility under decoherence due to environmental interactions. though there exist protocols to protect bipartite entanglement under decoherence, the implementation of such protocols for multipartite quantum correlations has not been sufficiently explored. here, we study the effect of local amplitude damping channel on the generalized greenberger - horne - zeilinger state, and use a protocol of optimal reversal quantum weak measurement to protect the multipartite quantum correlations.   we observe that the weak measurement reversal protocol enhances the robustness of multipartite quantum correlations.   further it increases the critical damping value that corresponds to entanglement sudden death. to emphasize the efficacy of the technique in protection of multipartite quantum correlation, we investigate two proximately related quantum communication tasks, namely, quantum teleportation in a one sender, many receivers setting and multiparty quantum information splitting, through a local amplitude damping channel.   we observe an increase in the average fidelity of both the quantum communication tasks under the weak measurement reversal protocol.   the method may prove beneficial, for combating external interactions, in other quantum information tasks using multipartite resources.
we discuss the fragmentation of primordial gas clouds in the universe after decoupling. comparing the time scale of collapse with that of fragmentation  , we obtain the typical mass of a fragment both numerically and analytically.   it is shown that the estimated mass gives the minimum mass of a fragment which is formed from the primordial gas cloud and is essentially determined by the _ chandrasekhar mass_.
we present new pre - maximum and late - time optical photometry of the type  ia / iin supernova 2002ic.   these observations are combined with the published v - band magnitudes of  @xcite and the vlt spectrophotometry of  @xcite to construct the most extensive light curve to date of this unusual supernova.   the observed flux at late time is significantly higher relative to the flux at maximum than that of any other observed type  ia supernova and continues to fade very slowly a year after explosion.   our analysis of the light curve suggests that a non - type ia supernova component becomes prominent @xmath0  days after explosion.   modeling of the non - type ia supernova component as heating from the shock interaction of the supernova ejecta with pre - existing circumstellar material suggests the presence of a @xmath1  cm gap or trough between the progenitor system and the surrounding circumstellar material.   this gap could be due to significantly lower mass - loss @xmath2  years prior to explosion or evacuation of the circumstellar material by a low - density fast wind.   the latter is consistent with observed properties of proto - planetary nebulae and with models of white - dwarf + asymptotic giant branch star progenitor systems with the asymptotic giant branch star in the proto - planetary nebula phase.
the theory of polar magnetic burial in accreting neutron stars predicts that a mountain of accreted material accumulates at the magnetic poles of the star, and that, as the mountain spreads equatorward, it is confined by, and compresses, the equatorial magnetic field.   here, we extend previous, axisymmetric, grad - shafranov calculations of the hydromagnetic structure of a magnetic mountain up to accreted masses as high as @xmath0, by importing the output from previous calculations ( which were limited by numerical problems and the formation of closed bubbles to @xmath1 ) into the time - dependent, ideal - magnetohydrodynamic code zeus-3d and loading additional mass onto the star dynamically.   the rise of buoyant magnetic bubbles through the accreted layer is observed in these experiments.   we also investigate the stability of the resulting hydromagnetic equilibria by perturbing them in zeus-3d.   surprisingly, it is observed that the equilibria are marginally stable for all @xmath2 ; the mountain oscillates persistently when perturbed, in a combination of alfvn and acoustic modes, without appreciable damping or growth, and is therefore not disrupted ( apart from a transient parker instability initially, which expels @xmath3 of the mass and magnetic flux ).   accretion, accretion discs  pulsars  stars : magnetic fields  stars : neutron
the present status of our understanding of low mass dilepton production in relativistic heavy ion collisions is discussed  . the focus of the discussion will be the sensitivity of dilepton measurements to in medium changes of hadrons and the restoration of chiral symmetry.   we will finally discuss how the presence of strong long wavelength pion modes, i.e. disoriented chiral condensates can be seen in the dilepton spectrum.   +     +
we present a technique to construct a spectropolarimetrically accurate magneto - hydrostatic model of a large - scale solar magnetic field concentration, mimicking a sunspot. using the constructed model we perform a simulation of acoustic wave propagation, conversion and absorption in the solar interior and photosphere with the sunspot embedded into it. with the @xmath0 magnetically sensitive photospheric absorption line of neutral iron,   we calculate observable quantities such as continuum intensities, doppler velocities, as well as full stokes vector for the simulation at various positions at the solar disk, and analyse the influence of non - locality of radiative transport in the solar photosphere on helioseismic measurements.   bisector shapes were used to perform multi - height observations.   the differences in acoustic power at different heights within the line formation region at different positions at the solar disk were simulated and characterised.   an increase in acoustic power in the simulated observations of the sunspot umbra away from the solar disk centre was confirmed as the slow magneto - acoustic wave.
we consider a minimal classically scale - invariant extension of the standard model. in this theory,   the higgs mechanism is triggered and the electroweak symmetry breaking is generated radiatively by the coleman - weinberg sector which is coupled to the sm higgs.   we extend the higgs portal interactions of the theory to include an additional singlet which is also non - minimally coupled to gravity.   this generates a single - field slow - roll inflation mechanism in the effective field theory formulation which is robust up to planck scales.   our approach does not require integrating in any additional new physics degrees of freedom to unitarise the theory in the sub - planckian regime where inflation happens. as a result  , no large threshold corrections appear in our approach to inflation so that the electroweak scale and the sm higgs mass are not affected.   the singlet field responsible for inflation also gives a viable dark matter candidate in our model.   we also discuss the relation between classical scale - invariance of the effective theory and the possible local scale invariance of the full theory and comment on the naturalness of the electroweak scale.   = 1
single linear polymer chains in dilute solutions under good solvent conditions are studied by monte carlo simulations with the pruned - enriched rosenbluth method up to the chain length @xmath0.   based on the standard simple cubic lattice model ( sclm ) with fixed bond length and the bond fluctuation model ( bfm ) with bond lengths in a range between @xmath1 and @xmath2, we investigate the conformations of polymer chains described by self - avoiding walks ( saws ) on the simple cubic lattice, and by random walks ( rws ) and non - reversible random walks ( nrrws ) in the absence of excluded volume ( ev ) interactions.   in addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential.   the persistence lengths of chains extracted from the orientational correlations are estimated for all cases.   we show that chains based on the bfm are more flexible than those based on the sclm for a fixed bending energy.   the microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified.   our simulations clarify that a different mapping ratio between the coarse - grained models and the atomistically realistic description of polymers is required in a coarse - graining approach due to the different crossovers to the asymptotic behavior.
after removing the double - well potential trapping two initially independent bose condensates, the density expectation value is calculated when both the exchange symmetry of identical bosons and interatomic interaction are considered.   the density expectation value and evolution equations are obtained based on both the first - quantization and second - quantization methods.   when the interatomic interaction is considered carefully, after the overlapping of two initially independent condensates, it is shown that there is a nonzero interference term in the density expectation value.   it is found that the calculated density expectation value with this model agrees with the interference pattern observed in the experiment by andrews _   et al _ _   ( science * 275 *, 637 ( 1997))_. the nonzero interference term in the density expectation value physically arises from the exchange symmetry of identical bosons and interatomic interaction which make two initially independent condensates become coherent after the overlapping. for two initially independent condensates, our researches show that there is an interaction - induced coherence process.
for several years, periodical arrays of subwavelength cylindrical holes in thin metallic layers have taken a crucial importance in the context of the results reported by ebbesen _   et al, _ on particularly attractive optical transmission experiments.   it had been underlined that the zeroth order transmission pattern does not depend on the polarization of the incident light at normal incidence. in the present paper, we show that it is not the case for rectangular holes, by contrast to the case of circular holes. in this context, we suggest a new kind of polarizer that present the advantages brought by the original ebbesen devices. assuming the recent technological interest for these kinds of metallic gratings, such a kind of polarizer could lead to new technological applications.
semi - supervised template update systems allow to automatically take into account the intra - class variability of the biometric data over time.   such systems can be inefficient by including too many impostor s samples or skipping too many genuine s samples. in the first case  , the biometric reference drifts from the real biometric data and attracts more often impostors. in the second case  , the biometric reference does not evolve quickly enough and also progressively drifts from the real biometric data.   we propose a hybrid system using several biometric sub - references in order to increase performance of self - update systems by reducing the previously cited errors.   the proposition is validated for a keystroke - dynamics authentication system ( this modality suffers of high variability over time ) on two consequent datasets from the state of the art.
we present a simple method to stabilize the optical path length of an optical fiber to an accuracy of about 1/100 of the laser wavelength.   we study the dynamic response of the path length to modulation of an electrically conductive heater layer of the fiber.   the path length is measured against the laser wavelength by use of the pound - drever - hall method ; negative feedback is applied via the heater.   we apply the method in the context of a cryogenic resonator frequency standard.
motivated by the problem of sorting, we introduce two simple combinatorial models with distinct hamiltonians yet identical spectra ( and hence partition function ) and show that the local dynamics of these models are very different. after a deep quench, one model slowly relaxes to the sorted state whereas the other model becomes blocked by the presence of stable local minima.
+ we report on the status of our qcd thermodynamics project.   it is performed on the qcdoc machine at brookhaven national laboratory and the apenext machine at bielefeld university. using a 2 + 1 flavor formulation of qcd at almost realistic quark masses we calculated several thermodynamical quantities. in this proceeding   we show the susceptibilites of the chiral condensate and the polyakov loop, the static quark potential and the spatial string tension.
iron, the universe s most abundant refractory element, is highly depleted in both circumstellar and interstellar environments, meaning it exists in solid form.   the nature of this solid is unknown. in this letter  , we provide evidence that metallic iron grains are present around oxygen - rich agb stars, where it is observationally manifest as a featureless mid - infrared excess.   this identification is made using _   spitzer space telescope _   observations of evolved globular cluster stars, where iron dust production appears ubiquitous and in some cases can be modelled as the only observed dust product. in this context  , feo is examined as the likely carrier for the 20-@xmath0 m feature observed in some of these stars.   metallic iron appears to be an important part of the dust condensation sequence at low metallicity, and subsequently plays an influential rle in the interstellar medium.   we explore the stellar metallicities and luminosities at which iron formation is observed, and how the presence of iron affects the outflow and its chemistry.   the conditions under which iron can provide sufficient opacity to drive a wind remain unclear.
we show how methods of continuum perturbation theory can be used to simplify perturbative lattice calculations.   we use the technique of asymptotic expansions to expand lattice loop integrals around the continuum limit. after the expansion,   all nontrivial dependence on momenta and masses is encoded in continuum loop integrals and the only genuine lattice integrals left are tadpole integrals. using integration - by - parts relations   all of these can be expressed in terms of a small number of master integrals.   four master integrals are needed for bosonic one loop integrals, sixteen in qcd with wilson or staggered fermions.   
we develop the concept of * abc*-boost ( * * a**daptive * * b**ase * * c**lass boost ) for multi - class classification and present * abc*-mart, a concrete implementation of * abc*-boost.   the original mart ( * * m**ultiple * * a**dditive * * r**egression * * t**rees ) algorithm has been very successful in large - scale applications. for binary classification,   abc - mart recovers mart. for multi - class classification,   abc - mart considerably improves mart, as evaluated on several public data sets.
rush hour logic was introduced in @xcite as a model of computation inspired by the `` rush hour '' toy puzzle, in which cars can move horizontally or vertically within a parking lot.   the authors show how the model supports polynomial space computation, using certain car configurations as building blocks to construct boolean circuits for a cpu and memory.   they consider the use of cars of length 3 crucial to their construction, and conjecture that cars of size 2 only, which we ll call _ size 2 rush hour _, do not support polynomial space computation.   we settle this conjecture by showing that the required building blocks are constructible in size 2 rush hour.   furthermore, we consider unit rush hour, which was hitherto believed to be trivial, show its relation to maze puzzles, and provide empirical support for its hardness.
we investigate the applicability of a random - matrix model to the description of non - collective excitations in heavy - ion reactions around the coulomb barrier. to this end, we study fusion in the reaction @xmath0o + @xmath1pb, taking account of the known non - collective excitations in the @xmath1pb nucleus. we show that the random - matrix model for the corresponding couplings reproduces reasonably well the exact calculations, obtained using empirical deformation parameters.   this implies that the model may provide a powerful method for systems in which the non - collective couplings are not so well known.
we investigate multi - field inflationary scenarios with fields that drop out of the model in a staggered fashion.   this feature is natural in certain multi - field inflationary setups within string theory ; for instance, it can manifest itself when fields are related to tachyons that condense, or inter - brane distances that become meaningless when branes annihilate. considering a separable potential, and promoting the number of fields to a smooth time - dependent function  , we derive the formalism to deal with these models at the background and perturbed level, providing general expressions for the scalar spectral index and the running.   we recover known results of e.g. a dynamically relaxing cosmological constant in the appropriate limits.   we further show that isocurvature perturbations are suppressed during inflation, so that perturbations are adiabatic and nearly gaussian.   the resulting setup might be interpreted as a novel type of warm inflation, readily implemented within string theory and without many of the shortcomings associated with warm inflation.    to exemplify the applicability of the formalism we consider three concrete models : assisted inflation with exponential potentials as a simple toy model ( a graceful exit becomes possible ), inflation from multiple tachyons ( a constant decay rate of the number of fields and negligible slow roll contributions turns out to be in good agreement with observations ) and inflation from multiple m5-branes within m - theory ( a narrow stacking of branes yields a consistent scenario ).
interaction between collective monopole oscillations of a trapped bose - einstein condensate and thermal excitations is investigated by means of perturbation theory.   we assume spherical symmetry to calculate the matrix elements by solving the linearized gross - pitaevskii equations.   we use them to study the resonances of the condensate induced by temperature when an external perturbation of the trapping frequency is applied and to calculate the landau damping of the oscillations.
we study the asymptotic behavior of the spectral gap of simple barrier tunneling problems, which are related to using quantum annealing to find the global optimum of cost functions defined over @xmath0 bits.   specifically we look at the problem of having an @xmath0 qubit system tunnel through a barrier of width and height proportional to @xmath1.   we show that with these quantum annealing problems, the asymptotic, @xmath2, behavior of the spectral gap does not accurately describe the behavior of the gap at finite @xmath0 until extremely large values of @xmath0 ( @xmath3 ).   we prove that this deficiency of the asymptotic expression is a feature of simple one - dimensional tunneling problems themselves, casting doubt on whether asymptotic analysis is an appropriate tool for studying tunneling problems in quantum annealing for reasonably sized systems.
we report the discovery of a variable blue straggler in the core of the globular cluster m5, based on a 12-hour long series of images obtained with the planetary camera aboard the _ hubble space telescope_. in addition, we present the light curves of 28 previously unknown or poorly studied large - amplitude variable stars ( all but one are rr lyrae ) in the cluster core.   a ( v, u - i ) color - magnitude diagram shows 24 blue stragglers within 2 core radii of the cluster center.   the blue straggler population is significantly more centrally concentrated than the horizontal branch and red giant stars.
we discuss the interpretation of transient, unpulsed radio emission detected from the unique pulsar / be - star binary system psr b1259@xmath063.   extensive monitoring of the 1994 and 1997 periastron passages has shown that the source flares over a 100-day interval around periastron, varying on time - scales as short as a day and peaking at 60 mjy ( @xmath1 times the apastron flux density ) at 1.4 ghz. interpreting the emission as synchrotron radiation  , we show that ( i ) the observed variations in flux density are too large to be caused by the shock interaction between the pulsar wind and an isotropic, radiatively driven, be - star wind, and ( ii ) the radio emitting electrons do not originate from the pulsar wind.   we argue instead that the radio electrons originate from the circumstellar disk of the be star and are accelerated at two epochs, one before and one after periastron, when the pulsar passes through the disk.   a simple model incorporating two epochs of impulsive acceleration followed by synchrotron cooling reproduces the essential features of the radio light curve and spectrum and is consistent with the system geometry inferred from pulsed radio data.   astrophysical journal letters, in press    original : 4 may 1998. revised : 29 june 1998, 10 december 1998
traditional databases are not equipped with the adequate functionality to handle the volume and variety of `` big data ''. strict schema definition and data loading   are prerequisites even for the most primitive query session.   raw data processing has been proposed as a schema - on - demand alternative that provides instant access to the data. when loading is an option, it is driven exclusively by the current - running query, resulting in sub - optimal performance across a query workload. in this paper, we investigate the problem of workload - driven raw data processing with partial loading.   we model loading as fully - replicated binary vertical partitioning.   we provide a linear mixed integer programming optimization formulation that we prove to be np - hard.   we design a two - stage heuristic that comes within close range of the optimal solution in a fraction of the time.   we extend the optimization formulation and the heuristic to pipelined raw data processing, scenario in which data access and extraction are executed concurrently.   we provide three case - studies over real data formats that confirm the accuracy of the model when implemented in a state - of - the - art pipelined operator for raw data processing.
advancing qcd toward astroparticle applications generates new challenges for perturbation theory, such as the presence of large evolution scales with sizeable scaling violations involving both the initial and the final state of a collision.   possible applications in the context of ultra high energy cosmic rays ( uhecr ) of these effects are discussed.    _   dedicated to the memory of prof.   nathan isgur _
we investigate the formation process of planetesimals from the dust layer by the gravitational instability in the gas disk using local @xmath0-body simulations.   the gas is modeled as a background laminar flow.   we study the formation process of planetesimals and its dependence on the strength of the gas drag.   our simulation results show that the formation process is divided into three stages qualitatively : the formation of wake - like density structures, the creation of planetesimal seeds, and their collisional growth.   the linear analysis of the dissipative gravitational instability shows that the dust layer is secularly unstable although toomre s @xmath1 value is larger than unity.   however, in the initial stage, the growth time of the gravitational instability is longer than that of the dust sedimentation and the decrease in the velocity dispersion. thus, the velocity dispersion decreases and the disk shrinks vertically. as the velocity dispersion becomes sufficiently small, the gravitational instability finally becomes dominant. then wake - like density structures are formed by the gravitational instability.   these structures fragment into planetesimal seeds.   the seeds grow rapidly owing to mutual collisions.
solar prominences are long - lived cool and dense plasma curtains in the hot and rarefied outer solar atmosphere or corona.   the physical mechanism responsible for their formation and especially for their internal plasma circulation has been uncertain for decades.   the observed ubiquitous down flows in quiescent prominences are difficult to interpret as plasma with high conductivity seems to move across horizontal magnetic field lines.   here we present three - dimensional numerical simulations of prominence formation and evolution in an elongated magnetic flux rope as a result of in - situ plasma condensations fueled by continuous plasma evaporation from the solar chromosphere.   the prominence is born and maintained in a fragmented, highly dynamic state with continuous reappearance of multiple blobs and thread structures that move mainly downward dragging along mass - loaded field lines.   the prominence plasma circulation is characterized by the dynamic balance between the drainage of prominence plasma back to the chromosphere and the formation of prominence plasma via continuous condensation.   plasma evaporates from the chromosphere, condenses into the prominence in the corona, and drains back to the chromosphere, establishing a stable chromosphere - corona plasma cycle.   synthetic images of the modeled prominence with the solar dynamics observatory atmospheric imaging assembly closely resemble actual observations, with many dynamical threads underlying an elliptical coronal cavity.
we present a detailed optical study of the ultra - compact x - ray binary 4u0614 + 091.   we have used 63hrs of time - resolved optical photometry taken with three different telescopes ( iac80, not and spm ) to search for optical modulations.   the power spectra of each dataset reveals sinusoidal modulations with different periods, which are not always present.   the strongest modulation has a period of 51.3mins, a semi - amplitude of 4.6mmags, and is present in the iac80 data.   the spm and not data show periods of 42mins and 64mins respectively, but with much weaker amplitudes, 2.6mags and 1.3mmags respectively.   these modulations arise from either x - ray irradiation of the inner face of the secondary star and/or a superhump modulation from the accretion disc, or quasi - periodic modulations in the accretion disc.   it is unclear whether these periods / quasi - periodic modulations are related to the orbital period, however, the strongest period of 51.3mins is close to earlier tentative orbital periods.   further observations taken over a long base - line are encouraged.
one of the most discussed peculiarities of einstein s theory of relativity is the twin paradox, the fact that the time between two events in space - time appears to depend on the path between these events.   we show that this time discrepancy results only from faulty assumptions in the transition from one reference system to another  . the twin paradox does not exist.   but the lorentz invariance of the theory has strong consequences, if we assume that it is valid not only locally, but also on cosmic scale.
we generalize the kinetic theory of fluids, in which the description of fluids is based on the geodesic motion of particles, to spacetimes modeled by finsler geometry.   our results show that finsler spacetimes are a suitable background for fluid dynamics and that the equation of motion for a collisionless fluid is given by the liouville equation, as it is also the case for a metric background geometry.   we finally apply this model to collisionless dust and a general fluid with cosmological symmetry and derive the corresponding equations of motion.   it turns out that the equation of motion for a dust fluid is a simple generalization of the well - known euler equations.
the unidentified x - ray source rx j0720.4 - 3125 is a candidate isolated neutron star showing evidence for _ pulsed _ emission with an 8.39 s period and a spectrum consistent with a blackbody at @xmath0 ev ( haberl _ et al.   _ 1996, 1997 ).   we show that this source is most likely an old isolated neutron star accreting from surrounding media.   we then argue that unless it was born with a long spin period ( @xmath1 seconds ) _ and _ weak field ( @xmath2 ), the magnetic field on this star _ must _ have decayed. with @xmath3,   we find decay timescales @xmath4 yrs for power law decay or @xmath5 yrs for exponential decay. a measured period derivative @xmath6 s@xmath7s@xmath8 would be consistent with an old accreting isolated neutron star.   both power law and exponential decay models can give a @xmath9 s@xmath7s@xmath8, though a @xmath10 substantially less than this would be indicative of exponential field decay.    _   subject headings : _ pulsars : general  stars : individual ( rx j0720.4 - 3125 )     stars : magnetic fields  stars : neutron  x - rays : stars
we study born - infeld type effective action for unstable d3-brane system including a tachyon and an abelian gauge field, and find the rolling tachyon with constant electric and magnetic fields as the most general homogeneous solution.   tachyonic vacua are characterized by magnitudes of the electric and magnetic fields and the angle between them.   analysis of small fluctuations in this background shows that the obtained configuration may be interpreted as a fluid consisting of string - like objects carrying electric and magnetic fields.   they are stretched along one direction and the rolling tachyon move in a perpendicular direction to the strings.   direction of the propagating waves coincides with that of strings with velocity equal to electric field.   =.22 in    hep - th/0301076    * electromagnetic string fluid in rolling tachyon * + chanju kimewha.ac.kr ], hang bae kimipt.unil.ch ], yoonbai kimskku.ac.kr ], and o - kab kwonnewton.skku.ac.kr ] + _ @xmath0department of physics, ewha womans university, seoul 120 - 750, korea _   + _ @xmath1institute of theoretical physics, university of lausanne, ch-1015 lausanne, switzerland _ + _ @xmath2bk21 physics research division and institute of basic science, sungkyunkwan university, + suwon 440 - 746, korea _ + _ @xmath3 school of physics, korea institute for advanced study, + 207 - 43, cheongryangri - dong, dongdaemun - gu, seoul 130 - 012, korea _    _ keywords _ : rolling tachyon, dirac - born -
the expansion of an initially unmagnetized planar rarefaction wave has recently been shown to trigger a thermal anisotropy - driven weibel instability ( tawi ), which can generate magnetic fields from noise levels.   it is examined here if the tawi can also grow in a curved rarefaction wave.   the expansion of an initially unmagnetized circular plasma cloud, which consists of protons and hot electrons, into a vacuum is modelled for this purpose with a two - dimensional particle - in - cell ( pic ) simulation.   it is shown that the momentum transfer from the electrons to the radially accelerating protons can indeed trigger a tawi.   radial current channels form and the aperiodic growth of a magnetowave is observed, which has a magnetic field that is oriented orthogonal to the simulation plane.   the induced electric field implies that the electron density gradient is no longer parallel to the electric field.   evidence is presented here for that this electric field modification triggers a second magnetic instability, which results in a rotational low - frequency magnetowave.   the relevance of the tawi is discussed for the growth of small - scale magnetic fields in astrophysical environments, which are needed to explain the electromagnetic emissions by astrophysical jets.   it is outlined how this instability could be examined experimentally.
in strong magnetic fields the transport coefficients of strange quark matter become anisotropic.   we determine the general form of the complete set of transport coefficients in the presence of a strong magnetic field. by using a local linear response method,   we calculate explicitly the bulk viscosities @xmath0 and @xmath1 transverse and parallel to the @xmath2-field respectively, which arise due to the non - leptonic weak processes @xmath3.   we find that for magnetic fields @xmath4 g, the dependence of @xmath0 and @xmath1 on the field is weak, and they can be approximated by the bulk viscosity for zero magnetic field. for fields @xmath5 g, the dependence of both @xmath0 and @xmath1 on the field is strong, and they exhibit de haas - van alphen - type oscillations. with increasing magnetic field, the amplitude of these oscillations increases, which eventually leads to negative @xmath0 in some regions of parameter space.   we show that the change of sign of @xmath0 signals a hydrodynamic instability. as an application  , we discuss the effects of the new bulk viscosities on the r - mode instability in rotating strange quark stars.   we find that the instability region in strange quark stars is affected when the magnetic fields exceeds the value @xmath6 g. for fields which are larger by an order of magnitude, the instability region is significantly enlarged, making magnetized strange stars more susceptible to @xmath7-mode instability than their unmagnetized counterparts.
we describe a grid generation procedure designed to construct new classes of orthogonal coordinate systems for binary black hole spacetimes.   the computed coordinates offer an alternative approach to current methods, in addition to providing a framework for potentially more stable and accurate evolutions of colliding black holes. as a particular example  , we apply our procedure to generate appropriate numerical grids to evolve misner s axisymmetric initial data set representing two equal mass black holes colliding head  on.   these new results are compared with previously published calculations, and we find generally good agreement in both the waveform profiles and total radiated energies over the allowable range of separation parameters. furthermore, because no specialized treatment of the coordinate singularities is required, these new grids are more easily extendible to unequal mass and spinning black hole collisions.    epsf.sty
the hamiltonian of the gravitational field defined in a bounded region is quantized.   the classical hamiltonian, and starting point for the regularization, is a boundary term required by functional differentiability of the hamiltonian constraint.   it is the quasilocal energy of the system and becomes the adm mass in asymptopia.   the quantization is carried out within the framework of canonical quantization using spin networks.   the result is a gauge invariant, well - defined operator on the hilbert space induced by the state space on the whole spatial manifold. the spectrum is computed. an alternate form of the operator, with the correct naive classical limit, but requiring a restriction on the hilbert space, is also defined.   comparison with earlier work and several consequences are briefly explored.   uwthph-1999 - 40
in this paper, the behavior of a spherical hole in an otherwise infinite and uniform universe is investigated.   first, the newtonian theory is developed.   the concept of negative gravity, an outward gravitational force acting away from the center of the spherical hole, is presented, and the resulting expansion of the hole is investigated. then, the same result is derived using the techniques of einstein s theory of general relativity.   the field equations are solved for an infinite uniform universe and then for an infinite universe in which matter is uniformly distributed except for a spherical hole.   negative pressure caused by negative gravity is utilized.   the physical significance of the cosmological constant is explained, and a new physical concept, that of the gravitational potential of a hole, is discussed. the relationship between the newtonian potential for a hole and the schwarzschild solution of the field equations   is explored.   finally, the geodesic equations are considered.   it is shown that photons and particles are deflected away from the hole.   an application of this idea is pursued, in which a new cosmology based upon expanding holes in a uniform universe is developed.   the microwave background radiation and hubble s law, among others, are explained.   finally, current astronomical data are used to compute a remarkably accurate value of hubble s constant, as well as estimates of the average mass density of the universe and the cosmological constant.   i v u    = 1
we investigate the magnetism of the co^ii^@xmath0(oh)@xmath1(c@xmath2@xmath3h@xmath2@xmath4o@xmath0)@xmath5 metal - organic framework which displays complex inorganic chains separated from each other by distances of 1 to 2 nm, and which orders at 5.4  k. the zero - field magnetic structure is determined using neutron powder diffraction : it is mainly antiferromagnetic but posseses a ferromagnetic component along the * c*-axis.   this magnetic structure persists in presence of a magnetic field.   ac susceptibility measurements confirm the existence of a single thermally activated regime over 7 decades in frequency ( e / k@xmath6 k ) whereas time - dependent relaxation of the magnetization after saturation in an external field leads to a two times smaller energy barrier.   these experiments probe the slow dynamics of domain walls within the chains : we propose that the ac measurements are sensitive to the motion of existing domain walls within the chains, while the magnetization measurements are governed by the creation of domain walls.
we propose a scheme to characterize the non - markovian dynamics and quantify the non - markovianity via the non - classicality measured by the negativity of quantumness. by considering a qubit in contact with a critical ising spin bath and introducing an ancilla  , we show that revivals of negativity of quantumness indicate the non - markovian dynamics.   furthermore, a normalized measure of non - markovianity based on the negativity of quantumness is introduced and the influences of bath criticality, bath temperature and bath size on the non - markovianity are discussed.   it is shown that, at the critical point, the decay of non - markovianity versus the size of spin bath is fastest and the non - markovianity is exactly zero only in the thermodynamic limit. besides, non - trivial behaviours of negativity of quantumness such as sudden change, double sudden changes and keeping constant are found for different relations between parameters of the initial state. finally, how the non - classicality of the system is affected by a series of bang - bang pulses is also examined.
how to analyze terabytes of photometric data, and extract knowledge on variable stars? how to detect variable phenomena? how to combine different photometric bands?   which algorithm to search for periods? how to characterize and classify the detected variable objects?   many questions, but certainly no definitive answers yet.   we present several aspects which are at the interface of photometric surveys and variable stars.   fully automated analyses of photometric surveys are still not at an optimized level.   we will take the example of a future survey, the gaia mission project of the european space agency, to show different steps of a possible automated pipeline scheme.   principal component analysis can be applied to the gaia photometric bands.   we give some illustrative examples of classification methods such as support vector machine, self - organizing map, or bayesian classifier.
in this work we consider an abelian o(3 ) sigma model coupled nonminimally with a gauge field governed by maxwell and chern - simons terms.   bogomolnyi equations are constructed for a _ specific form _ of the potential and generic nonminimal coupling constant.   furthermore, topological and nontopological self - dual soliton solutions are obtained for a critical value of the nonminimal coupling constant. some particular static vortex solutions ( topological and nontopological ) satisfying the bogomolnyi bound   are numerically solved and presented.   # 1 # 1( )   ,    and
i present the latest results from a search for hot molecular cores at mid - infrared wavelengths from the largest optical telescopes available at the present time.   three well - observed hot molecular cores were imaged, g29.96 - 0.02, g19.61 - 0.23, and g34.26 + 0.15. even though mid - infrared sources have been claimed to be detected previously at the hot molecular core locations of both g19.61 - 0.23 and g34.26 + 0.15, only the hot molecular core in g29.96 - 0.02 resulted in a detection.   new upper limits on mid - infrared emission are given for the hot molecular cores that were not detected.    1.25 in.125 in.25 in
the density dependence of the symmetry energy in the equation of state of asymmetric nuclear matter ( n / z @xmath0 1 ) is important for understanding the structure of systems as diverse as the atomic nuclei and neutron stars. due to a proper lack of understanding of the basic nucleon - nucleon interaction for matters that are highly asymmetric and at non - normal nuclear density  , this very important quantity has remained largely unconstrained.   recent studies using beams from the cyclotron institute of texas a@xmath1 m university, constraining the density dependence of the symmetry energy, is presented.   a dependence of the form e@xmath2 = c(@xmath3, where c = 31.6 mev and @xmath4 = 0.69, is obtained from the dynamical and statistical model analysis.   their implications to both astrophysical and nuclear physics studies are discussed.
it has been proposed that the global circulation of the atmosphere winds at 200  mb can be used as a criteria to establish the suitability of a site for the development of adaptive optics techniques such as slow wavefront corrugation correction. by using the noaa ncep / ncar reanalysis data base we analyze the monthly average wind velocity at 200@xmath0 mb for a 16 year period, for two sites in mexico : sierra negra and san pedro mrtir. we compare the results with those obtained for mauna kea, paranal and la silla, with maidanak in uzbekistan, and with gamsberg in namibia.   we show that for all the sites under study there is a yearly wind speed modulation and we model that modulation.   our results show that sierra negra and san pedro mrtir are comparable with the best observatory sites as mauna kea and are amongst themost advantageous sites to apply adaptive optics techniques.
the upper main sequence magnetic chemically peculiar ( ap ) stars exhibit a non - uniform distribution of chemical elements across their surfaces and with height in their atmospheres.   these inhomogeneities, responsible for the conspicuous photometric and spectroscopic variation of ap stars, are believed to be produced by atomic diffusion operating in the stellar atmospheres stabilized by multi - kg magnetic fields. here   i present an overview of the current state - of - the - art in understanding ap - star spots and their relation to magnetic fields.   in particular, i highlight recent 3-d chemical spot structure studies and summarize magnetic field mapping results based on the inversion of the full stokes vector spectropolarimetric observations.   i also discuss a puzzling new type of spotted stars, hgmn stars, in which the formation and evolution of heavy element spots is driven by a poorly understood mechanism, apparently unrelated to magnetic fields.
we reconsider a number of measurements for the overall hydration kinetics of tricalcium silicate pastes having an initial water to cement weight ratio close to @xmath0.   we find that the time dependent ratio of hydrated and unhydrated silica mole numbers can be well characterized by two power  laws in time, @xmath1. for early times   @xmath2 we find an ` accelerated'hydration ( @xmath3 ) and for later times @xmath4 a ` deaccelerated'behavior ( @xmath5 ).   the crossover time is estimated as @xmath6.   we interpret these results in terms of a global second order rate equation indicating that ( a ) hydrates catalyse the hydration process for @xmath7, ( b ) they inhibit further hydration for @xmath8 and ( c ) the value of the associated second order rate constant is of magnitude @xmath9.   we argue, by considering the hydration process actually being furnished as a diffusion limited precipitation that the exponents @xmath10 and @xmath11 directly indicate a preferentially ` plate'like hydrate microstructure.   this is essentially in agreement with experimental observations of cellular hydrate microstructures for this class of materials.   = -1.5 cm = = 0.3 cm = -0.54 cm = -0.54 cm    2
we consider friedel oscillation in the two - dimensional dirac materials when fermi level is near the van hove singularity.   twisted graphene bilayer and the surface state of topological crystalline insulator are the representative materials which show low - energy saddle points that are feasible to probe by gating.   we approximate the fermi surface near saddle point with a hyperbola and calculate the static lindhard response function. employing a theorem of lighthill, the induced charge density @xmath0 due to an impurity is obtained and the algebraic decay of @xmath0 is determined by the singularity of the static response function. although a hyperbolic fermi surface is rather different from a circular one, the static lindhard response function in the present case shows a singularity similar with the response function associated with circular fermi surface, which leads to the @xmath1 at large distance @xmath2.   the dependences of charge density on the fermi energy are different.   consequently, it is possible to observe in twisted graphene bilayer the evolution that @xmath3 near dirac point changes to @xmath1 above the saddle point.   measurements using scanning tunnelling microscopy around the impurity sites could verify the prediction.
electromagnetic processes in loosely bound nuclei are investigated using an analytical model. in particular, electromagnetic dissociation of @xmath0   is studied and the results of our analytical model are compared to numerical calculations based on a three - body picture of the @xmath0  bound state. the calculation of energy spectra is shown to be strongly model dependent.   this is demonstrated by investigating the sensitivity to the rms intercluster distance, the few - body behavior, and the effects of final state interaction.   in contrast, the fraction of the energy spectrum which can be attributed to e1 transitions is found to be almost model independent at small relative energies.   this finding is of great importance for astrophysical applications as it provides us with a new tool to extract the e1 component from measured energy spectra.   an additional, and independent, method is also proposed as it is demonstrated how two sets of experimental data, obtained with different beam energy and/or minimum impact parameter, can be used to extract the e1 component.
in this paper, we are analyzing the interactivity time, defined as the duration between two consecutive tasks such as sending emails, collecting friends and followers and writing comments in online social networks ( osns ).   the distributions of these times are heavy tailed and often described by a power - law distribution.   however, power - law distributions usually only fit the heavy tail of empirical data and ignore the information in the smaller value range. here, we argue that the durations between writing emails or comments, adding friends and receiving followers are likely to follow a lognormal distribution.   we discuss the similarities between power - law and lognormal distributions, show that binning of data can deform a lognormal to a power - law distribution and propose an explanation for the appearance of lognormal interactivity times.   the historical debate of similarities between lognormal and power - law distributions is reviewed by illustrating the resemblance of measurements in this paper with the historical problem of income and city size distributions.
millimeter and mid - infrared observations have been made of the dense clumps of dust and gas and of young stellar objects ( ysos ) associated with the bright, compact submillimeter source g79.3 + 0.3  p1 in the relatively nearby msx infrared - dark cloud g79.3 + 0.3.   the gemini mid - infrared observations reported here indicate the presence of three ysos within the cloud.   bima 3  mm continuum observations show that the brightest of the ysos is likely to be a herbig ae / be star.   high - angular - resolution molecular - line observations suggest that a wind from this star may be triggering collapse in the adjacent molecular cloud.   the submillimeter source g79.3 + 0.3  p1 itself does not contain infrared sources and may represent an earlier stage of star formation.
in this paper, we use bell inequality and nonlocality to study the bipartite correlation in an exactly soluble two - dimensional mixed spin system.   bell inequality turns out to be a valuable detector for phase transitions in this model.   it can detect not only the quantum phase transition, but also the thermal phase transitions, of the system.   the property of bipartite correlation in the system is also analyzed. in the quantum anti - ferromagnetic phase,   the bell inequality is violated thus nonlocality is present.   it is interesting that the nonlocality is enhanced by thermal fluctuation, and similar results have not been observed in anti - ferromagnetic phase. in the ferromagnetic phase,   the quantum correlation turns out to be very novel, which can not be captured by entanglement or nonlocality.   phase transition, nonlocality, bell inequality
sharp chemical discontinuities can occur in protoplanetary discs, particularly at ` snow - lines'where a gas - phase species freezes out to form ice grains.   such sharp discontinuities will diffuse out due to the turbulence suspected to drive angular momentum transport in accretion discs.   we demonstrate that the concentration gradient - in the vicinity of the snow - line - of a species present outside a snow - line but destroyed inside is strongly sensitive to the level of turbulent diffusion ( provided the chemical and transport time - scales are decoupled ) and provides a direct measurement of the radial ` schmidt number'( the ratio of the angular momentum transport to radial turbulent diffusion ). taking as an example the tracer species n@xmath0h@xmath1, which is expected to be destroyed inside the co snow - line ( as recently observed in tw hya ) we show that _ alma _ observations possess significant angular resolution to constrain the schmidt number.   since different turbulent driving mechanisms predict different schmidt numbers, a direct measurement of the schmidt number in accretion discs would allow inferences about the nature of the turbulence to be made.
motivated by cell adhesion in hydrodynamic flow, here we study bond formation between a spherical brownian particle in linear shear flow carrying receptors for ligands covering the boundary wall.   we derive the appropriate langevin equation which includes multiplicative noise due to position - dependent mobility functions resulting from the stokes equation.   we present a numerical scheme which allows to simulate it with high accuracy for all model parameters, including shear rate and three parameters describing receptor geometry ( distance, size and height of the receptor patches ). in the case of homogeneous coating  , the mean first passage time problem can be solved exactly. in the case of position - resolved receptor - ligand binding,   we identify different scaling regimes and discuss their biological relevance.
we study general stochastic birth and death processes including delay.   we develop several approaches for the analytical treatment of these non - markovian systems, valid, not only for constant delays, but also for stochastic delays with arbitrary probability distributions.   the interplay between stochasticity and delay and, in particular, the effects of delay in the fluctuations and time correlations are discussed.
we have analysed in detail the discovery measurements of the x - ray burster sax  j1750.8 - 2900 by the wide field cameras on board _ bepposax _ in spring 1997, at a position @xmath01.2 degrees off the galactic centre.   the source was in outburst on march 13th when the first observation started and showed x - ray emission for @xmath0  2 weeks.   a total of 9 bursts were detected, with peak intensities varying from @xmath10.4 to 1.0 crab in the 2 - 10 kev range.   most bursts showed a fast rise time ( @xmath11  s ), an exponential decay profile with e - folding time of @xmath15  s, spectral softening during decay, and a spectrum which is consistent with few kev blackbody radiation.   these features identify them as type - i x - ray bursts of thermonuclear origin.   the presence of type  i bursts and the source position close to the galactic centre favours the classification of this object as a neutron star low mass x - ray binary.   x - ray emission from sax  j1750.8 - 2900 was not detected in the previous and subsequent galactic bulge monitoring, and the source was never seen bursting again.
diffraction calculations, such as the angular spectrum method, and fresnel diffractions, are used for calculating scalar light propagation.   the calculations are used in wide - ranging optics fields : for example, computer generated holograms ( cghs ), digital holography, diffractive optical elements, microscopy, image encryption and decryption, three - dimensional analysis for optical devices and so on. however, increasing demands made by large - scale diffraction calculations have rendered the computational power of recent computers insufficient. we have already developed a numerical library for diffraction calculations using a graphic processing unit ( gpu ), which was named the gwo library.   however, this gwo library is not user - friendly, since it is based on c language and was also run only on a gpu. in this paper  , we develop a new c++ class library for diffraction and cgh calculations, which is referred as to a cwo++ library, running on a cpu and gpu.   we also describe the structure, performance, and usage examples of the cwo++ library.   diffraction, digital holography, digital holographic microscopy, graphics processing unit, gpgpu, gpu computing, holography, real - time holography, scalar light propagation
we analyze the extent to which the lhc and tevatron results as of the end of 2012 constrain invisible ( or undetected ) decays of the higgs boson - like state at @xmath0. to this end   we perform global fits for several cases : 1 )  a higgs boson with standard model ( sm ) couplings but additional invisible decay modes ; 2 )  sm couplings to fermions and vector bosons, but allowing for additional new particles modifying the effective higgs couplings to gluons and photons ; 3 )  no new particles in the loops but tree - level higgs couplings to the up - quarks, down - quarks and vector bosons, relative to the sm, treated as free parameters.   we find that in the three cases invisible decay rates of 23%, 61%, 88%, respectively, are consistent with current data at 95% confidence level ( cl ).   limiting the coupling to vector bosons, @xmath1, to @xmath2 in case 3 ) reduces the allowed invisible branching ratio to 56% at 95% cl. requiring in addition that the higgs couplings to quarks have the same sign as in the sm, an invisible rate of up to 36%   is allowed at 95%  cl.   we also discuss direct probes of invisible higgs decays, as well as the interplay with dark matter searches.   lapth-013/13 + lpsc 13039 + lpt 12 - 53 + ucd-2013 - 2     g.  blanger@xmath3, b.  dumont@xmath4, u.  ellwanger@xmath5, j.  f.  gunion@xmath6, s.  kraml@xmath4
a field in the vacuum state, which is in principle separable, can evolve to an entangled state in a dynamical gravitational collapse.   we will study, quantify, and discuss the origin of this entanglement, showing that it could even reach the maximal entanglement limit for low frequencies or very small black holes, with consequences in micro - black hole formation and the final stages of evaporating black holes.   this entanglement provides quantum information resources between the modes in the asymptotic future ( thermal hawking radiation ) and those which fall to the event horizon.   we will also show that fermions are more sensitive than bosons to this quantum entanglement generation.   this fact could be helpful in finding experimental evidence of the genuine quantum hawking effect in analog models.
in the perturbative approach, substructures in the lens can be reduced to their effect on the two perturbative fields @xmath0 and @xmath1.   a simple generic model of elliptical lens with a substructure situated near the critical radius is investigated in details.   analytical expressions are derived for each perturbative field, and basic properties are analyzed.   the power spectrum of the fields is well approximated by a power - law, resulting in significant tails at high frequencies.   another feature of the perturbation by a substructure is that the ratio of the power spectrum at order @xmath2 of the 2 fields @xmath3 is nearly 1.   the ratio @xmath4 is specific to substructures, for instance an higher order distortion ( @xmath5 ) but with auto - similar isophotes will result in @xmath6.   finally, the problem of reconstructing the perturbative field is investigated. local field model   are implemented and fitted to maximize image similarity in the source plane.   the non - linear optimization is greatly facilitated, since in the perturbative approach the circular source solution is always known.   examples of images distortions in the subcritical regime due to substructures are presented, and analyzed for different source shapes.   provided enough images and signal is available, the substructure field can be identified confidently.   these results suggests that the perturbative method is an efficient tool to estimate the contribution of substructures to the mass distribution of lenses.       gravitational lensing - strong lensing
we add a set of convex constraints to the lasso to produce sparse interaction models that honor the hierarchy restriction that an interaction only be included in a model if one or both variables are marginally important.   we give a precise characterization of the effect of this hierarchy constraint, prove that hierarchy holds with probability one and derive an unbiased estimate for the degrees of freedom of our estimator.   a bound on this estimate reveals the amount of fitting `` saved '' by the hierarchy constraint.   we distinguish between _ parameter sparsity_the number of nonzero coefficients  and _ practical sparsity_the number of raw variables one must _ measure _ to make a new prediction.   hierarchy focuses on the latter, which is more closely tied to important data collection concerns such as cost, time and effort.   we develop an algorithm, available in the ` r ` package ` hiernet `, and perform an empirical study of our method.   ,
we report an angle - resolved photoemission study of the charge stripe ordered la@xmath0nd@xmath1sr@xmath2cuo@xmath3 system.   a comparative and quantitative line shape analysis is presented as the system evolves from the overdoped regime into the charge ordered phase. on the overdoped side ( @xmath4 ), a normal state anti - nodal spectral gap opens upon cooling below  80  k. in this process spectral weight is preserved but redistributed to larger energies. a correlation between this spectral gap and electron scattering   is found.   a different lineshape is observed in the antinodal region of charge ordered nd - lsco @xmath5.   significant low - energy spectral weight appears to be lost.   these observations are discussed in terms of spectral weight redistribution and gapping originating from charge stripe ordering.
ngc 2355 is an old open cluster in the outer part of the galactic disk ( @xmath0, @xmath1 ) which has been little studied until now.   this paper presents the first astrometric and spectroscopic investigation of this cluster.   we have measured precise absolute proper motions from old carte du ciel plates, poss - i plates and recent ccd observations obtained with the bordeaux meridian circle.   the proper motion data reveal 38 highly probable cluster members down to @xmath2  mag within @xmath3 of the cluster center.   we have also obtained elodie high resolution spectra for 24 stars.   seventeen of them are confirmed to be members of the cluster on the basis of radial velocity.   eight of them are fast rotating turnoff stars for which the projected rotational velocity has been determined.   the spectroscopic observations have also provided estimates of the physical parameters @xmath4 } }, { m_\mathrm{v}}$ ] of the 24 target stars.   two stragglers have been identified in the cluster. combining our astrometric and spectroscopic results with previous ubv photometry and recent jhk@xmath5 photometry from the 2mass survey   we have derived the fundamental properties of the cluster : metallicity, age, distance, size, spatial velocity and orbit.
some of the rapidly oscillating ( cp2 ) stars, have  which are larger than the theoretical.   as the cut - off frequency depends on the @xmath0 relation in the atmosphere, we have computed  and adiabatic  for pulsating ap stars with @xmath1 laws based on kurucz model atmospheres and on hopf s purely radiative relation.   the frequency - dependent treatment of radiative transfer as well as an improved calculation of the radiative pressure in kurucz model atmospheres increase the theoretical   by about 200@xmath2hz, which is closer to the observations.    for @xmath3cir   we find models with kurucz atmospheres which have indeed a cut - off frequency beyond the largest observed frequency and which are well within the   @xmath4 error box. for hd24712 only models which are hotter by about 100k and less luminous by nearly 10% than what is actually the most probable value would have an  large enough.   one may thus speculate that the old controversy about a mismatch between observed largest frequencies and theoretical cut - off frequencies of roap star models is resolved. however, the observational errors for the astrophysical fundamental parameters have to be reduced further and the model atmospheres refined.   further details can be found in audard et al.   ( 1997 )    ii
the two - state model of stochastic resonance is extended to a chain of coupled two - state elements governed by the dynamics of glauber s stochastic ising model.   appropriate assumptions on the model parameters turn the chain into a prototype system of coupled stochastic resonators. in a weak - signal limit   analytical expressions are derived for the spectral power amplification and the signal - to - noise ratio of a two - state element embedded into the chain.   the effect of the coupling between the elements on both quantities is analysed and array - enhanced stochastic resonance is established for pure as well as noisy periodic signals.   the coupling - induced improvement of the snr compared to an uncoupled element is shown to be limited by a factor four which is only reached for vanishing input noise.
the huge and increasing demand of data connectivity motivates the development of new and effective power line communication ( plc ) channel models, which are able to faithfully describe a real communication scenario.   this is of fundamental importance since a good model represents a quick evaluation tool for new standards or devices, allowing a considerable saving in time and costs.   the aim of this paper is to discuss a novel top - down mimo plc synthetic channel model, able to numerically emulate a real plc environment.   first, the most common channel modeling strategies are briefly described, highlighting strengths and weaknesses.   afterwards, the basic model approach is described considering the siso scenario.   the implementation strategy is then extended to the mimo case.   the validity of the proposed model is proved making a comparison between the simulated channels and channels obtained with measurements in terms of both performance and statistical metrics.   the focus is on the broadband frequency spectrum.   power line communication, channel modeling, multiple - input multiple - output, indoor, synthetic model, top - down.
using a lagrangian mechanics approach, we construct a framework to study the dissipative properties of systems composed of two components one of which is highly lossy and the other is lossless.   we have shown in our previous work that for such a composite system the modes split into two distinct classes, high - loss and low - loss, according to their dissipative behavior.   a principal result of this paper is that for any such dissipative lagrangian system, with losses accounted by a rayleigh dissipative function, a rather universal phenomenon occurs, namely, _ selective overdamping _ :   the high - loss modes are all overdamped, i.e., non - oscillatory, as are an equal number of low - loss modes, but the rest of the low - loss modes remain oscillatory each with an extremely high quality factor that actually increases as the loss of the lossy component increases.   we prove this result using a new time dynamical characterization of overdamping in terms of a virial theorem for dissipative systems and the breaking of an equipartition of energy.
spectra towards the w3 complex are presented and used to probe the galactic structure and interstellar medium conditions between us and this region.   the overall shape of the spectra is consistent with the predictions of the two - arm spiral shock model wherein the gas found in the 40  to 50  range has been accelerated by some 20  from its rotation curve velocity.   spin temperatures of @xmath0100 k are derived for the local arm gas, lower than found in a previous, similar study towards dr 7. for the interarm region,   values on the order of 300 k are found, implying a negligible filling factor for the cold neutral medium ( @xmath1 ).   some of the absorbing gas at velocities near 40  is confirmed to be associated with the regions.
recently i proposed a simple dynamical network model for discrete space - time which self - organizes as a graph with hausdorff dimension @xmath0.   the model has a geometric quantum phase transition with disorder parameter @xmath1 where @xmath2 is the spectral dimension of the dynamical graph.   self - organization in this network model is based on a competition between a ferromagnetic ising model for vertices and an antiferromagnetic ising model for edges. in this paper   i solve a toy version of this model defined on a bipartite graph in the mean field approximation.   i show that the geometric phase transition corresponds exactly to the antiferromagnetic transition for edges, the dimensional disorder parameter of the former being mapped to the staggered magnetization order parameter of the latter.   the model has a critical point with long - range correlations between edges, where a continuum random geometry can be defined, exactly as in kazakov s famed 2d random lattice ising model but now in any number of dimensions.
we use simulations of star clusters to investigate the possible dynamical origins of the observed spread in core radius among intermediate - age and old star clusters in the large magellanic cloud ( lmc ).   two effects are considered, a time - varying external tidal field and variations in primordial hard binary fraction.   simulations of clusters orbiting a point - mass galaxy show similar core radius evolution for clusters on both circular and elliptical orbits and we therefore conclude that the tidal field of the lmc has not yet significantly influenced the evolution of the intermediate - age clusters.   the presence of large numbers of hard primordial binaries in a cluster leads to core radius expansion ; however, the magnitude of the effect is insufficient to explain the observations.   further, the range of binary fractions required to produce significant core radius growth is inconsistent with the observational evidence that all the lmc clusters have similar stellar luminosity functions.       galaxies : magellanic clouds, star clusters - globular clusters : general
edge reconstruction modifies the electronic properties of finite graphene samples. we formulate a low - energy theory of the reconstructed zigzag edge by deriving the modified boundary condition to the dirac equation.   if the unit cell size of the reconstructed edge is not a multiple of three with respect to the zigzag unit cell, valleys remain uncoupled and the edge reconstruction is accounted for by a single angular parameter @xmath0.   dispersive edge states exist generically, unless @xmath1. we compute @xmath0 from a microscopic model for the `` reczag '' reconstruction ( conversion of two hexagons into a pentagon - heptagon pair ) and   show that it can be measured via the local density of states. in a magnetic field there   appear three distinct edge modes in the lowest landau level, two of which are counterpropagating.
we investigate the ruderman - kittel - kasuya - yosida oscillations of the itinerant carrier spin density in a system where those oscillations appear only due to a finite distribution of a localized spin.   the system represents a half - infinite one - dimensional quantum wire with a magnetic impurity located at its edge.   in contrast to the conventional model of a point - like exchange interaction the itinerant carrier spin density oscillations in this system exist.   we _ analytically _ demonstrate that when the radius of the exchange interaction is less than the wave length of the itinerant carriers living on the fermi surface, the long range behavior of the oscillations is identical to the one taking place in the zero radius limit of the same exchange interaction but for an infinite one - dimensional quantum wire where, in comparison with the original half - infinite system, the mass of the itinerant carriers is _ strongly _ modified by the exchange interaction radius. on the basis of our analysis   we make a suggestion on directionality of surface ruderman - kittel - kasuya - yosida interaction shown in recent experiments : we believe that in general the anisotropy of the ruderman - kittel - kasuya - yosida interaction could result not only from the anisotropy of the _ fermi surface _ of itinerant carriers but also from the anisotropy of the _ spin carrying atomic orbitals _ of magnetic impurities.
in this paper we will look at the phenomenon of microwave amplification by stimulated emission of radiation ( a _ maser _ system ).   we begin by deriving amplification by stimulated emission using time - dependent perturbation theory, in which the perturbation provided by external radiation. when this perturbation is applied to an ensemble of particles exhibiting a population inversion, the result is stimulated microwave radiation.   we will explore both unsaturated and saturated masers and compare their properties. by understanding their gain, as well as the effect of _ line broadening _,   astronomers are to identify astrophysical masers. by studying such masers,   we gain new insight into poorly understood physical environments, particularly those around young and old stars, and compact stellar bodies.
a two - step measurement protocol of a quantum system, known as _ weak value _ ( wv ), has been introduced more than two decades ago by aharonov _   et al_.  @xcite, and has since been studied in various contexts. here   we discuss another two - step measurement protocol which we dub _   null weak value _ ( nwv ).   the protocol consists of a partial - collapse measurement followed by quantum manipulation on the system and finally a strong measurement.   the first step is a strong measurement which takes place with small probability.   the second strong measurement is used as postselection on the outcome of the earlier step.   not being measured in the partial - collapse stage ( null outcome ) leads to a non - trivial correlation between the two measurements.   the nvw protocol, first defined for a two - level system  @xcite, is generalized to a multi - level system, and compared to the standard - wv protocol.
the ground - state correlations are investigated for an isotropic transverse xy chain which is constrained to carry either a current of magnetization @xmath0 or a current of energy @xmath1.   we find that the effect of @xmath2 on the large - distance decay of correlations is twofold : i ) oscillations are introduced and ii ) the amplitude of the power law decay increases with increasing current.   the effect of energy current is more complex.   generically, correlations in current carrying states are found to decay faster than in the @xmath3 states, contrary to expectations that correlations are increased by the presence of currents.   however, increasing the current, one reaches a special line where the correlations become comparable to those of the @xmath4 states. on this line,   the symmetry of the ground state is enhanced and the transverse magnetization vanishes.   further increase of the current destroys the extra symmetry but the transverse magnetization remains at the high - symmetry, zero value.   + pacs numbers : 05.50.+q, 05.70.ln, 64.60.ht, 75.10.jm    = 10000    2
a new class of pattern forming systems is identified and investigated : anisotropic systems that are spatially inhomogeneous along the direction perpendicular to the preferred one. by studying the generic amplitude equation of this new class and a model equation,   we show that branched stripe patterns emerge, which for a given parameter set are stable within a band of different wavenumbers and different numbers of branching points ( defects ).   moreover, the branched patterns and unbranched ones ( defect - free stripes ) coexist over a finite parameter range.   we propose two systems where this generic scenario can be found experimentally, surface wrinkling on elastic substrates and electroconvection in nematic liquid crystals, and relate them to the findings from the amplitude equation.
we numerically study the tidal instability of accretion discs in close binary systems using a two - dimensional sph code.   we find that the precession rate of tidally unstable, eccentric discs does not only depend upon the binary mass ratio @xmath0.   although the ( prograde ) disc precession rate increases with the strength of the tidal potential, we find that increasing the shear viscosity @xmath1 also has a significant prograde effect. increasing the disc temperature has a retrograde impact upon the precession rate.   we find that motion relative to the binary potential results in superhump - like, periodic luminosity variations in the outer reaches of an eccentric disc.   the nature and location of the luminosity modulation is a function of @xmath1.   light curves most similar to observations are obtained for @xmath1 values appropriate for a dwarf nova in outburst.   we investigate the thermal - tidal instability model for superoutburst.   a dwarf nova outburst is simulated by instantaneously increasing @xmath1, which causes a rapid radial expansion of the disc.   should the disc encounter the @xmath2 eccentric inner lindblad resonance and become tidally unstable, then tidal torques become much more efficient at removing angular momentum from the disc.   the disc then shrinks and @xmath3 increases.   the resulting increase in disc luminosity is found to be consistent with the excess luminosity of a superoutburst.   = -1.0 cm    accretion, accretion discs  hydrodynamics  instabilities  methods : numerical  binaries : close  novae, cataclysmic variables
by combining the newly infrared photometric data from the all - sky data release of the _ wide - field infrared survey explorer _ with the spectroscopic data from the seventh data release of the sloan digital sky survey, we study the covering factor of warm dust ( @xmath0 ) for a large quasar sample, as well as the relations between @xmath0 and other physical parameters of quasars. we find a strong correlation between the flux ratio of mid - infrared to near - ultraviolet and the slope of near - ultraviolet spectra, which is interpreted as the dust extinction effect. after correcting for the dust extinction utilizing the above correlation, we examine the relations between @xmath0 and agn properties : bolometric luminosity ( @xmath1 ), black hole mass ( @xmath2 ) and eddington ratio ( @xmath3 ).   we confirm the anti - correlation between @xmath0 and @xmath1.   further we find that @xmath0 is anti - correlated with @xmath2, but is independent of @xmath3.   radio - loud quasars are found to follow the same correlations as for radio - quiet quasars.   monte carlo simulations show that the anisotropy of uv - optical continuum of the accretion disc can significantly affect, but is less likely to dominate the @xmath0@xmath1 correlation.       catalogues  galaxies : active  quasars : general  infrared : galaxies
we report on the detection of four new stellar debris streams and a new dwarf galaxy candidate in the sloan digital sky survey.   three of the streams, ranging between 3 and 15 kpc in distance and spanning between 37   and 84   on the sky, are very narrow and are most probably tidal streams originating in extant or disrupted globular clusters.   the fourth stream is much broader, roughly 45 kpc distant, at least 53   in length, and is most likely the tidal debris from a dwarf galaxy. as the streams each span multiple constellations, we extend tradition and designate them the acheron, cocytos, lethe, and styx streams. at the same distance and apparently embedded in the styx stream is a @xmath0 kpc - wide concentration of stars with an apparently similar color - magnitude distribution which we designate bootes iii. given its very low surface density, its location within the stream, and its apparently disturbed morphology, we argue that bootes iii may be the progenitor of styx and in possibly the final throes of tidal dissolution. while the current data do not permit strong constraints, preliminary orbit estimates for the streams do not point to any likely progenitors among the known globular clusters and dwarf galaxies.
this study addresses the mitigation of a nonlinear resonance of a mechanical system. in view of the narrow bandwidth of the classical linear tuned vibration absorber, a nonlinear absorber, termed the nonlinear tuned vibration absorber ( nltva ),   is introduced in this paper.   an unconventional aspect of the nltva is that the mathematical form of its restoring force is tailored according to the nonlinear restoring force of the primary system.   the nltva parameters are then determined using a nonlinear generalization of den hartog s equal - peak method. the mitigation of the resonant vibrations of a duffing oscillator is considered to illustrate the proposed developments.    _   keywords _ : nonlinear resonances, vibration absorber, nonlinearity synthesis, equal - peak method.   authors postprint version + published in : mechanical systems and signal processing ( 2014 ) + doi:10.1016/j.ymssp.2014.08.009 + http://www.sciencedirect.com/science/article/pii/s0888327014003252 + g. habib, t. detroux, r. vigui, g. kerschen +    space structures and systems laboratory + department of aerospace and mechanical engineering + university of liege, liege, belgium + e - mail : giuseppe.habib,tdetroux,g.kerschen@ulg.ac.be +   ''' ''   ''' ''    corresponding author : + giuseppe habib + space structures and systems laboratory + department of aerospace and mechanical engineering + university of liege + 1 chemin des chevreuils ( b52/3 ), b-4000 lige, belgium. +   email : giuseppe.habib@ulg.ac
the nonlocal properties of the w states are investigated under particle loss. by removing all but two particles from an @xmath0-qubit w state  , the resulting two - qubit state is still entangled.   hence, the w state has high persistency of entanglement.   we ask an analogous question regarding the persistency of nonlocality introduced in [ phys.   rev.   a 86, 042113 ].   namely, we inquire what is the minimal number of particles that must be removed from the w state so that the resulting state becomes local.   we bound this value in function of @xmath0 qubits by considering bell nonlocality tests with two alternative settings per site.   in particular, we find that this value is between @xmath1 and @xmath2 for large @xmath0.   we also develop a framework to establish bounds for more than two settings per site.
we consider an special dynamics of a quantum walk ( qw ) on a line.   initially, the walker localized at the origin of the line with arbitrary chirality, evolves to an asymptotic stationary state. in this stationary state   a measurement is performed and the state resulting from this measurement is used to start a second qw evolution to achieve a second asymptotic stationary state. in previous works, we developed the thermodynamics associated with the entanglement between the coin and position degrees of freedom in the qw.   here we study the application of the first and second laws of thermodynamics to the process between the two stationary states mentioned above.   we show that : i ) the entropy change has upper and lower bounds that are obtained analytically as a function of the initial conditions.   ii ) the energy change is associated to a heat - transfer process.   ,    quantum thermodynamic ; quantum walk + pacs : 03.67.-a ; 05.30.-d
in this article we review the standard versions of the central and of the lvy - gnedenko limit theorems, and illustrate their application to the convolution of independent random variables associated with the distribution @xmath0 ^{\frac{1}{1-q}}$ ] @xmath1 ), known as @xmath2-gaussian.   this distribution emerges upon extremisation of the nonadditive entropy @xmath3 ^{q}\ dx\right ) /\left ( 1-q\right ) $ ], basis of nonextensive statistical mechanics.   it has a finite variance for @xmath4, and an infinite one for @xmath5.   we exhibit that, in the case of ( standard ) independence, the @xmath2-gaussian has either the gaussian ( if @xmath6 ) or the @xmath7-stable lvy distributions ( if @xmath8 ) as its attractor in probability space.   moreover, we review a generalisation of the product, the @xmath2-product, which plays a central role in the approach of the specially correlated variables emerging within the nonextensive theory.   address = centro brasileiro de pesquisas fsicas, 150, 22290 - 180, rio de janeiro - rj, brazil, altaddress = santa fe institute, 1399 hyde park road, santa fe,   new mexico 87501, usa     address = centro brasileiro de pesquisas fsicas, 150, 22290 - 180, rio de janeiro - rj, brazil
we study the effects of hadronic rescattering on hadron distributions in high - energy nuclear collisions by using an integrated dynamical approach.   this approach is based on a hybrid model combining ( 3 + 1)-dimensional ideal hydrodynamics for the quark gluon plasma ( qgp ), and a transport model for the hadron resonance gas.   since the hadron distributions are the result of the entire expansion history of the system, understanding the qgp properties requires investigating how rescattering during the hadronic stage affects the final distributions of hadrons.   we include multistrange hadrons in our study, and quantify the effects of hadronic rescattering on their mean transverse momenta and elliptic flow.   we find that multistrange hadrons scatter less during the hadronic stage than non - strange particles, and thus their distributions reflect the properties of the system in an earlier stage than the distributions of non - strange particles.
the electron - electron correlations in a many - electron ( @xmath0 ) quantum dot confined by a parabolic potential is investigated in the presence of a single magnetic ion and a perpendicular magnetic field.   we obtained the energy spectrum and calculated the addition energy which exhibits cusps as function of the magnetic field.   the vortex properties of the many - particle wave function of the ground state are studied and for large magnetic fields are related to composite fermions.   the position of the impurity influences strongly the spin pair correlation function when the external field is large  . in small applied magnetic field, the spin exchange energy together with the zeeman terms leads to a ferromagnetic - antiferromagnetic(fm - afm ) transition. when the magnetic ion is shifted away from the center of the quantum dot a remarkable re - entrant afm - fm - afm transition   is found as function of the strength of the coulomb interaction.   thermodynamic quantities as the heat capacity, the magnetization, and the susceptibility are also studied.   cusps in the energy levels show up as peaks in the heat capacity and the susceptibility.
we consider pair production in a space - time - dependent background field and derive a source term, i.e., production rate in the one - particle phase space.   such a source term is required in boltzmann - equation - based models of quark - gluon plasma formation and evolution.   we compare the source term derived here with the one that has been used in the literature so far.   significant differences are observed.   pacs : 12.38.mh, 25.75.-q, 25.75.dw    keywords : relativistic heavy - ion collisions, quark - gluon plasma, pair production from space - time - dependent background field, preequilibrium phenomena    e - mail : bhalerao@theory.tifr.res.in,   fax : 091 22 215 2110   e - mail : vravi@iitk.ernet.in,   fax : 091 0512 250260
ratios of sample percentiles or of quantiles based on a single sample are often published for skewed income data to illustrate aspects of income inequality, but distribution - free confidence intervals for such ratios are not available in the literature. here   we derive and compare two large - sample methods for obtaining such intervals.   they both require good distribution - free estimates of the quantile density at the quantiles of interest, and such estimates have recently become available.   simulation studies for various sample sizes are carried out for pareto, lognormal and exponential distributions, as well as fitted generalized lambda distributions, to determine the coverage probabilities and widths of the intervals.   robustness of the estimators to contamination or a positive proportion of zero incomes is examined via influence functions and simulations.   the motivating example is australian household income data where ratios of quantiles measure inequality, but of course these results apply equally to data from other countries.    _   keywords : generalized lambda distribution ; influence function ; mixture distribution ; quantile density ; ratio of percentiles. _
a thin plate or slab, prepared so that opposite faces have different surface stresses, will bend as a result of the stress difference.   we have developed a classical molecular dynamics ( md ) formulation where ( similar in spirit to constant - pressure md ) the curvature of the slab enters as an additional dynamical degree of freedom.   the equations of motion of the atoms have been modified according to a variable metric, and an additional equation of motion for the curvature is introduced.   we demonstrate the method to au surfaces, both clean and covered with pb adsorbates, using many - body glue potentials.   applications to stepped surfaces, deconstruction and other surface phenomena are under study.   preprint sissa * 60/98/cm / ss * + submitted to _ physical review b _
we present extensive first principles density functional theory ( dft ) calculations dedicated to analyze the magnetic and electronic properties of small v@xmath0 clusters ( n=1,2,3,4,5,6 ) embedded in a cu fcc matrix.   we consider different cluster structures such as : i ) a single v impurity, ii ) several v@xmath1 dimers having different interatomic distance and varying local atomic environment, iii ) v@xmath2 and iv ) v@xmath3 clusters for which we assume compact as well as 2- and 1-dimensional atomic configurations and finally, in the case of the v ) v@xmath4 and vi ) v@xmath5 structures we consider a square pyramid and a square bipyramid together with linear arrays, respectively. in all cases,   the v atoms are embedded as substitutional impurities in the cu network. in general, and as in the free standing case, we have found that the v clusters tend to form compact atomic arrays within the cooper matrix.   our calculated non spin - polarized density of states at the v sites shows a complex peaked structure around the fermi level that strongly changes as a function of both the interatomic distance and local atomic environment, a result that anticipates a non trivial magnetic behavior.   in fact, our dft calculations reveal, in each one of our clusters systems, the existence of different magnetic solutions ( ferromagnetic, ferrimagnetic, and antiferromagnetic ) with very small energy differences among them, a result that could lead to the existence of complex finite - temperature magnetic properties.   finally, we compare our results with recent experimental measurements.
new families of exact general relativistic thick disks are constructed using the `` displace, cut, fill and reflect '' method.   a class of functions used to `` fill '' the disks is derived imposing conditions on the first and second derivatives to generate physically acceptable disks.   the analysis of the function s curvature further restrict the ranges of the free parameters that allow phisically acceptable disks.   then this class of functions together with the schwarzschild metric is employed to construct thick disks in isotropic, weyl and schwarzschild canonical coordinates. in these last   coordinates an additional function must be added to one of the metric coefficients to generate exact disks.   disks in isotropic and weyl coordinates satisfy all energy conditions, but those in schwarzschild canonical coordinates do not satisfy the dominant energy condition.   pacs numbers : 04.20.jb, 04.40.-b
we study the full counting statistics ( fcs ) in a single - molecule magnet ( smm ) with finite coulomb interaction @xmath0. for finite @xmath0 the fcs,   differing from @xmath1, shows a symmetric gate - voltage - dependence when the coupling strengths with two electrodes are interchanged, which can be observed experimentally just by reversing the bias - voltage.   moreover, we find that the effect of finite @xmath0 on shot noise depends on the internal level structure of the smm and the coupling asymmetry of the smm with two electrodes as well.   when the coupling of the smm with the incident - electrode is stronger than that with the outgoing - electrode, the super - poissonian shot noise in the sequential tunneling regime appears under relatively small gate - voltage and relatively large finite @xmath0, and dose not for @xmath1 ; while it occurs at relatively large gate - voltage for the opposite coupling case.   the formation mechanism of super - poissonian shot noise can be qualitatively attributed to the competition between fast and slow transport channels.    counting statistics ; single - molecule magnet ; coulomb interaction    pacs : 75.50.xx, 72.70.+m, 73.63.-b
ordinary differential equations ( odes ) are widely used to model biological, ( bio-)chemical and technical processes.   the parameters of these odes are often estimated from experimental data using ode - constrained optimisation.   this article proposes a simple simulation - based approach for solving optimisation problems with steady state constraints relying on an ode.   this simulation - based optimisation method is tailored to the problem structure and exploits the local geometry of the steady state manifold and its stability properties.   a parameterisation of the steady state manifold is not required.   we prove local convergence of the method for locally strictly convex objective functions.   efficiency and reliability of the proposed method are demonstrated in two examples.   the proposed method demonstrated better convergence properties than existing general purpose methods and a significantly higher number of converged starts per time.
we present new results on 158@xmath0 emission from four galaxies in the reionization epoch.   these galaxies were previously confirmed to be at redshifts between 6.6 and 7.15 from the presence of the ly@xmath1 emission line in their spectra.   the ly@xmath1 emission line is redshifted by 100 - 200 km s@xmath2 compared to the systemic redshift given by the  line.   these velocity offsets are smaller than what is observed in @xmath3 lyman break galaxies with similar uv luminosities and emission line properties.   smaller velocity shifts reduce the visibility of ly@xmath1 and hence somewhat alleviate the need for a very neutral igm at @xmath4 7 to explain the drop in the fraction of ly@xmath1 emitters observed at this epoch.   the galaxies show  emission with l=@xmath5 : these luminosities place them consistently below the sfr - l relation observed for low redshift star forming and metal poor galaxies and also below z=5.5 lyman break galaxies with similar star formation rates. we argue that previous undetections of  in @xmath47 galaxies with similar or smaller star formation rates are due to selection effects : previous targets were mostly strong ly@xmath1 emitters and therefore probably metal poor systems, while our galaxies are more representative of the general high redshift star forming population.
in an interferometer, no interference happens if the quanta s path information is available in an ancillary system.   one can erase this information by an appropriate measurement and recognize subensembles of the interferometry data showing interference.   we consider symmetric mach - zehnder or michelson interferometers in which a qudit, initially prepared in a pure state, provides the path information.   we set measures of which - path information and which - phase information ( knowledge about the phase difference between the interferometer s arms ) by use of shannon entropy and show that by erasing the which - path information, one can obtain the same amount of which - phase information.   as an example, we propose a new modified michelson interferometer, feasible by today s technology, in which a qubit ( an atom trapped in a cavity ) gathers the photon s path information.   erasing is done by measuring the atom s energy.   = 1
the topological interference management problem refers to the study of the capacity of partially connected linear ( wired and wireless ) communication networks with no channel state information at the transmitters ( no csit ) beyond the network topology, i.e., a knowledge of which channel coefficients are zero ( weaker than the noise floor in the wireless case ).   while the problem is originally studied with fixed topology, in this work we explore the implications of varying connectivity, through a series of simple and conceptually representative examples.   specifically, we highlight the synergistic benefits of coding across alternating topologies.
the crystal ball spectrometer, with its nearly complete angular coverage, is an efficient detector of photon and neutron final states.   while installed in the c6 beamline of the alternating gradient synchrotron ( ags ) of brookhaven national laboratory ( bnl ), this feature was used in a series of precise measurements of reactions with all - neutral final states. here   we concentrate on the analysis of data from the pion - induced reactions : @xmath0, @xmath1, @xmath2, and @xmath3.
in this paper we study centrifugal acceleration of particles moving along a prescribed rotating curved trajectories.   we consider the physical system embedded in an isotropic photon field and study the influence of the photon drag force on the acceleration process.   for this purpose we study three major configurations of the field lines : the straight line ; the archimede s spiral and the dipolar field line configuration. by analysing dynamics of particles sliding along the field lines in the equatorial plane   we have found several interesting features of motion. in particular, it has been shown that for rectilinear field lines the particles reach the light cylinder ( area where the linear velocity of rotation exactly equals the speed of light ) zone relatively slowly for bigger drag forces.   considering the archimede s spiral, we have found that in cases when the field lines lag behind the rotation, the particles achieve the force - free regime of dynamics regardless of the drag force. unlike this scenario, when the spiral is screwed up in an opposite direction there the particles do not reach the force free regime, but tend to stable equilibrium locations.   such a behaviour has been found for straight field lines as well.
we have improved upon the method of smoothing supernovae data to reconstruct the expansion history of the universe, @xmath0, using two latest datasets, gold and snls.   the reconstruction process does not employ any parameterisation and is independent of any dark energy model.   the reconstructed @xmath0 is used to derive the distance factor @xmath1 up to redshift @xmath2 and the results are compared with the given value of @xmath1 from detection of baryon acoustic oscillation peak ( bao ).   we find very good agreement between supernovae observations and the results from bao for @xmath3.   the estimated values of @xmath4 are completely model - independent and are only based on observational data.   the derived values of @xmath4 are then used to reconstruct the equation of state of dark energy, @xmath5. using our smoothing method   we can demonstrate that while snls data are in very good agreement with @xmath6cdm, the gold sample slightly prefers evolving dark energy.   we also show that proper estimation of the equation of state of dark energy at the high redshifts would be impossible at the current status of observations.   cosmology : theory  cosmological parameters
we show that tools from circuit complexity can be used to study decompositions of global constraints.   in particular, we study decompositions of global constraints into conjunctive normal form with the property that unit propagation on the decomposition enforces the same level of consistency as a specialized propagation algorithm.   we prove that a constraint propagator has a a polynomial size decomposition if and only if it can be computed by a polynomial size monotone boolean circuit.   lower bounds on the size of monotone boolean circuits thus translate to lower bounds on the size of decompositions of global constraints. for instance  , we prove that there is no polynomial sized decomposition of the domain consistency propagator for the constraint.
we present new calculations for the stark broadening of the hydrogen line profiles in the dense atmospheres of white dwarf stars.   our improved model is based on the unified theory of stark broadening from vidal, cooper & smith, but it also includes non - ideal gas effects from the hummer & mihalas occupation probability formalism directly inside the line profile calculations.   this approach improves upon previous calculations that relied on the use of an ad - hoc free parameter to describe the dissolution of the line wing opacity in the presence of high electric microfields in the plasma.   we present here the first grid of model spectra for hot ( @xmath0  k ) da white dwarfs that has no free parameters.   the atmospheric parameters obtained from optical and uv spectroscopic observations using these improved models are shown to differ substantially from those published in previous studies.
we report total - energy calculations based on the density - functional theory that clarify microscopic mechanisms of initial stage of graphene formation on the sic(0001 ) surface.   we explore favorable reactions for desorption of either si or c atoms from the stepped surface by determining the desorption and the subsequent migration pathways and calculating the corresponding energy barriers for the first time.   we find that the energy barrier for the desorption of an si atom at the step edge and the subsequent migration toward stable terrace sites are lower than that of a c atom by 0.75 ev, indicative of the selective desorption of si from the sic surface.   we also find that the subsequent si desorption is an exothermic reaction.   this exothermicity comes from the energy gain due to the bond formation of c atoms being left near the step edges.   this is certainly a seed of graphene flakes.
a study of the dynamics of the positive charges in liquid argon has been carried out in the context of the future massive time projection chambers proposed for dark matter and neutrino physics.   given their small mobility coefficient in liquid argon, the ions spend a considerably longer time in the active volume with respect to the electrons.   the positive charge density can be additionally increased by the injection, in the liquid volume, of the ions produced by the electron multiplying devices located in gas argon.   the impact of the ion current on the uniformity of the field has been evaluated as well as the probability of the charge signal quenching due to the electron - ion recombination along the drift.   the study results show some potential concerns for massive detectors with drift of many meters operated on surface.
this report covers investigation of the structural properties of surfaces of si epitaxial layers deposited on si(001 ) vicinal substrates with different miscuts.   we have shown processes of generation and growth of surface defects to depend on tilt direction of a si(001 ) wafer and epilayer growth mode.   we suppose these effects to be connected with interaction of monoatomic steps.
the systematics of ob spectra are reviewed in the optical domain, dominated by photospheric lines, and in the far ultraviolet ( both _ iue _ and _ fuse _ ranges ), in which the stellar - wind profiles dominate.   first, the two - dimensional ( temperature, luminosity ) trends in normal spectra are surveyed.   then, the normal reference frame having been established, various categories of peculiar objects can be distinguished relative to it, which reveal several phenomena of structural and/or evolutionary significance. included are cno anomalies at both early and late o types, three varieties of rapid rotators, hot and cool of / wn transition objects, and the recently discovered second known magnetic o star. the importance of both optical and uv observations to understand these phenomena is emphasized ; for instance, progress in understanding the structure of the new o - type magnetic oblique rotator is hampered by the current lack of a uv spectrograph.   while progress in the physical interpretation of these trends and anomalies has been and is being made, increased attention to modeling the systematics would accelerate future progress in this author s opinion.   finally, preliminary results from a _ chandra _ high - resolution survey of ob x - ray spectra ( pi w. waldron ) are presented.   they provide evidence that, just as emerged earlier in the uv, systematic morphological trends exist in the x - ray domain that are correlated with the optical spectral types, and hence the fundamental stellar parameters, contrary to prevailing opinion.
we discuss a few current developments in the use of quantum mechanically coherent systems for information processing. in each of these developments,   rolf landauer has played a crucial role in nudging us and other workers in the field into asking the right questions, some of which we have been lucky enough to answer. a general overview of the key ideas of quantum error correction is given.   we discuss how quantum entanglement is the key to protecting quantum states from decoherence in a manner which, in a theoretical sense, is as effective as the protection of digital data from bit noise.   we also discuss five general criteria which must be satisfied to implement a quantum computer in the laboratory, and we illustrate the application of these criteria by discussing our ideas for creating a quantum computer out of the spin states of coupled quantum dots.
we propose a new eulerian numerical approach for constructing the forward flow maps in continuous dynamical systems.   the new algorithm improves the original formulation developed in @xcite so that the associated partial differential equations ( pdes ) are solved forward in time and, therefore, the _ forward _ flow map can now be determined _ on the fly_. due to the simplicity in the implementations, we are now able to efficiently compute the unstable coherent structures in the flow based on quantities like the finite time lyapunov exponent ( ftle ), the finite size lyapunov exponent ( fsle ) and also a related infinitesimal size lyapunov exponent ( isle ). when applied to the isle computations, the eulerian method is in particularly computational efficient. for each separation factor   @xmath0 in the definition of the isle, typical lagrangian methods require to shoot and monitor an individual set of ray trajectories.   if the scale factor in the definition is changed, these methods have to restart the whole computations all over again.   the proposed eulerian method, however, requires to extract only an isosurface of a volumetric data for an individual value of @xmath0 which can be easily done using any well - developed efficient interpolation method or simply an isosurface extraction algorithm.   moreover, we provide a theoretical link between the ftle and the isle fields which explains the similarity in these solutions observed in various applications.
a more extended low density region of coexisting uniform antiferromagnetism and d - wave superconductivity has been reported in multilayer cuprates, when compared to single or bilayer cuprates.   this coexistence could be due to the enhanced screening of random potential modulations in inner layers or to the interlayer heisenberg and josephson couplings.   a theoretical analysis using a renormalized mean field theory, favors the former explanation.   the potential for an improved determination of the antiferromagnetic and superconducting order parameters in an ideal single layer from zero field nmr and infrared josephson plasma resonances in multilayer cuprates is discussed.
we consider a georgi - glashow model conformally coupled to gravity.   the conformally invariant action includes a triplet of scalar fields and @xmath0 non - abelian gauge fields.   however, the usual mass term @xmath1 is forbidden by the symmetry and this role is now played by the conformal coupling of the ricci scalar to the scalar fields. spontaneous symmetry breaking occurs via gravitation.   the spherically symmetric solutions correspond to localized solitons ( magnetic monopoles ) in asymptotically anti - de - sitter ( ads ) space - time and the metric outside the core of the monopole is found to be schwarzschild - ads.   though conformal symmetry excludes the einstein - hilbert term in the original action, it emerges in the effective action after spontaneous symmetry breaking and dominates the low - energy / long - distance regime outside the core of the monopole.   =.5 cm
grover s algorithm for quantum search can also be applied to classical energy transfer.   the procedure takes a system in which the total energy is equally distributed among @xmath0 subsystems and transfers most of the it to one marked subsystem.   we show that in a relativistic setting the efficiency of this procedure can be improved.   we will consider the transfer of relativistic kinetic energy in a series of elastic collisions. in this case, the number of steps of the energy transfer procedure approaches 1 as the initial velocities of the objects become closer to the speed of light.   this is a consequence of introducing non - linearities in the procedure.   however, the maximum attainable transfer will depend on the particular combination of speed and number of objects. in the procedure  , we will use @xmath0 elements, like in the classical case, instead of the @xmath1 states of the quantum algorithm.
we obtain new hi and @xmath0co images around supernova remnants ( snr ) kes 69 and g21.5 - 0.9. by comparing hi spectra with @xmath0co emission spectra, we significantly revise the kinematic distance for kes 69 to @xmath1 5.5 kpc, which was 11.2 kpc, and refine the kinematic distance for g21.5 - 0.9 to @xmath1 4.8 kpc. for kes 69,   the highest velocity of absorption is @xmath1 86 km s@xmath2 and a prominent hi emission feature at @xmath1 112 km s@xmath2 has no respective absorption.   these new results suggest that kes 69 is associated with a newly detected extended 1720 mhz oh maser at velocity of @xmath1 85 km s@xmath2 that originates from within the bright southern radio shell of kes 69. for g21.5 - 0.9,   the highest velocity of absorption is @xmath1 67 km s@xmath2.   the hi absorption spectra of the nearby bright source pmn j1832 - 1035 and of kes 69 show a common absorption feature at velocity of @xmath1 69 km s@xmath2, which is not seen for g21.5 - 0.9  . the resulting velocity of @xmath1 68 km s@xmath2 gives the best distance estimate of @xmath1 4.8 kpc for g21.5 - 0.9 and associated young pulsar j1833 - 1034.       supernova remnants - masers - pulsars : individual : j1833 - 1034 - cosmic rays - methods : data analysis
two decades after the discovery of 51  peg  b, the formation processes and atmospheres of short - period gas giants remain poorly understood. observations of eccentric systems provide key insights on those topics as they can illuminate how a planet s atmosphere responds to changes in incident flux.   we report here the analysis of multi - day multi - channel photometry of the eccentric ( @xmath0 ) hot jupiter hd  80606  b obtained with the _ spitzer space telescope_. the planet s extreme eccentricity combined with the long coverage and exquisite precision of new periastron - passage observations allow us to break the degeneracy between the radiative and dynamical timescales of hd  80606  b s atmosphere and constrain its global thermal response.   our analysis reveals that the atmospheric layers probed heat rapidly ( @xmath1-hr radiative timescale ) from @xmath2k to 1400k as they absorb @xmath3 of the incoming stellar flux during the periastron passage, while the planet s rotation period is @xmath4 hours, which exceeds the predicted pseudo - synchronous period ( 40 hours ).
in this paper we investigate the possibility of measuring the post - newtonian general relativistic gravitomagnetic lense - thirring effect in the jovian system of its galilean satellites io, europa, ganymede and callisto in view of recent developments in processing and modelling their optical observations spanning a large time interval ( 125 years ).   the present day best observations have an accuracy between several kilometers to few tens of kilometers, which is just the order of magnitude of the lense - thirring shifts of the orbits of the galilean satellites over almost a century. from a comparison between analytical development and numerical integration   it turns out that, unfortunately, most of the secular component of the gravitomagnetic signature is removed in the process of fitting the initial conditions.   indeed, an estimation of the magnitude of the lense - thirring effect in the ephemerides residuals is given ; the resulting residuals have a maximum magnitude of 20 meters only ( over 125 years ).
photons in cavities have been already used for the realization of simple quantum gates [ q.a.   turchette _   et al. _,   phys. rev  . lett. * 75 *, 4710 ( 1995 ) ].   we present a method for combatting decoherence in this case.
a challenging problem in computational mathematics is to compute roots of a high - degree univariate random polynomial.   we combine an efficient multiprecision implementation for solving high - degree random polynomials with two certification methods, namely smale s @xmath0-theory and one based on gerschgorin s theorem, for showing that a given numerical approximation is in the quadratic convergence region of newton s method of some exact solution. with this combination, we can _ certifiably count _ the number of real roots of random polynomials.   we quantify the difference between the two certification procedures and list the salient features of both of them.   after benchmarking on random polynomials where the coefficients are drawn from the gaussian distribution, we obtain novel experimental results for the  cauchy  distribution  case.
+ it is shown that different distinguishability measures impose different orderings on ensembles of @xmath0 pure quantum states.   this is demonstrated using ensembles of equally - probable, linearly independent, symmetrical pure states, with the maximum probabilities of correct hypothesis testing and unambiguous state discrimination being the distinguishability measures.   this finding implies that there is no absolute scale for comparing the distinguishability of any two ensembles of @xmath0 quantum states, and that distinguishability comparison is necessarily relative to a particular discrimination strategy.
we derive general results for the mass shift of bound states with angular momentum @xmath0 in a periodic cubic box in two and three spatial dimensions.   our results have applications to lattice simulations of hadronic molecules, halo nuclei, and feshbach molecules.   the sign of the mass shift can be related to the symmetry properties of the state under consideration.   we verify our analytical results with explicit numerical calculations.   moreover, we comment on the relations connecting the effective range parameter, the binding momentum of a given state and the asymptotic normalization coefficient of the corresponding wave function.   we give explicit expressions for this relation in the shallow binding limit.
we construct a model of cyg x-1 which describes self - consistently its emission from soft x - rays to mev @xmath0-rays. instead of a compact pair - dominated @xmath0-ray emitting region  , we consider a hot optically thin and spatially extended proton - dominated cloud surrounding the whole accretion disc.   the @xmath0-ray emission is due to bremsstrahlung, comptonization, and positron annihilation, while the corona - disc model is retained for the x - ray emission.   we show that the cyg x-1 spectrum accumulated by osse, batse, and comptel in 199195, as well as the heao-3 @xmath1 and @xmath2 spectra can be well fitted by our model ( see @xcite for details ).   the derived parameters are in qualitative agreement with the picture in which the spectral changes are governed by the mass flow rate in the accretion disc. in this context  , the hot outer corona could be treated as the advection - dominated flow co - existing with a standard thin accretion disc.
in this paper, we give a characterization of the visibility graphs of pseudo - polygons.   we first identify some key combinatorial properties of pseudo - polygons, and we then give a set of five necessary conditions based off our identified properties.   we then prove that these necessary conditions are also sufficient via a reduction to a characterization of vertex - edge visibility graphs given by orourke and streinu.
we study the stochastic behavior of heterogeneous diffusion processes with the power - law dependence @xmath0 of the generalized diffusion coefficient encompassing sub- and superdiffusive anomalous diffusion. based on statistical measures such as   the amplitude scatter of the time averaged mean squared displacement of individual realizations, the ergodicity breaking and non - gaussianity parameters, as well as the probability density function @xmath1 we analyze the weakly non - ergodic character of the heterogeneous diffusion process and, particularly, the degree of irreproducibility of individual realization. as we show  , the fluctuations between individual realizations increase with growing modulus @xmath2 of the scaling exponent.   the fluctuations appear to diverge when the critical value @xmath3 is approached, while for even larger @xmath4 the fluctuations decrease, again. at criticality,   the power - law behavior of the mean squared displacement changes to an exponentially fast growth, and the fluctuations of the time averaged mean squared displacement do not seem to converge for increasing number of realizations. from a systematic comparison we observe some striking similarities of the heterogeneous diffusion process with the familiar subdiffusive continuous time random walk process with power - law waiting time distribution and diverging characteristic waiting time.
a solar - type dynamo model in a spherical shell is developed with allowance for random dependence of the poloidal field generation mechanism on time and latitude.   the model shows repeatable epochs of strongly decreased amplitude of magnetic cycles similar to the maunder minimum of solar activity.   random dependence of dynamo - parameters on latitude brakes the equatorial symmetry of generated fields.   the model shows the correlation of the occurrence of grand minima with deviations in the dynamo - field from dipolar parity.   an increased north - south asymmetry of magnetic activity can, therefore, be an indicator of transitions to grand minima. qualitative interpretation of this correlation is suggested.   statistics of grand minima in the model are close to the poisson random process indicating that the onset of a grand minimum is statistically independent of preceding minima.
we describe a simple experiment for measuring the thermal expansion coefficient of a metal wire and discuss how the experiment can be used as a tool for exploring the interplay of measurement uncertainty and scientific models.   in particular, we probe the regimes of applicability of three models of the wire : stiff and massless, elastic and massless, and elastic and massive. using both analytical and empirical techniques, we present the conditions under which the wire s mass and elasticity can be neglected. by accounting for these effects,   we measure nichrome s thermal expansion coefficient to be @xmath0  @xmath1m / m@xmath2k, which is consistent with the accepted value at the 8% level.
we have conducted an optical and infrared imaging in the neighbourhoods of 4 triplets of quasars.   r, z@xmath0, j and k@xmath1 images were obtained with mosaic ii and ispi at cerro tololo interamerican observatory.   accurate relative photometry and astrometry were obtained from these images for subsequent use in deriving photometric redshifts.   we analyzed the homogeneity and depth of the photometric catalog by comparing with results coming from the literature.   the good agreement shows that our magnitudes are reliable to study large scale structure reaching limiting magnitudes of r = 24.5, z@xmath0 = 22.5, j = 20.5 and k@xmath1 = 19.0. with this catalog we can study the neighbourhoods of the triplets of quasars searching for galaxy overdensities such as groups and galaxy clusters.        galaxies : quasars - general, galaxies : photometry
we investigate the @xmath0 theory of gravity with broken diffeomorphism due to the change of the coefficient in front of the total divergence term in the ( @xmath1)-decomposition of the scalar curvature.   we perform the canonical analysis of this theory and show that its consistent, i.e. with no unphysical degrees of freedom, form is equivalent to the low - energy limit of the non - projectable @xmath0 hoava - lifshitz theory of gravity.   we also analyze its cosmological solutions and show that the de sitter solution can be obtained also in the case of this broken symmetry.   the consequences of the proposed theory on the asymptotic solutions of a few specific models in the cosmological context are also presented.    0.4 cm    * restricted @xmath0 gravity and its cosmological implications *    m. chaichian,@xmath2 a. ghalee,@xmath3 j. kluso,@xmath4 + @xmath2__department of physics, university of helsinki, p.o.   box 64, + fi-00014 helsinki, finland _ _   + @xmath3__department of physics, tafresh university, tafresh, iran _   _ + @xmath5__department of theoretical physics and astrophysics, faculty of science, + masaryk university, kotlsk 2, 611 37, brno, czech republic _ _    0.8 cm    # 1 # 1x^(#1 )    # 1\{#1 }
we present the first high - resolution n - body / sph simulations that follow the evolution of low surface brightness disk satellites in a primary halo containing both dark matter and a hot gas component.   tidal shocks turn the stellar disk into a spheroid with low @xmath0 and remove most of the outer dark and baryonic mass.   in addition, by weakening the potential well of the dwarf tides enhance the effect of ram pressure, and the gas is stripped down to radius three times smaller than the stellar component.   a very low gas / stars ratio results after several gyr, similarly to what seen in dwarf spheroidal satellites of the milky way and m31.   # 1_#1 _ # 1_#1 _ = @scaling.95 # 1@scaling#1 # 1=@scaling
we present a study of site and bond percolation on periodic lattices with ( on average ) fewer than three nearest neighbors per site.   we have studied this issue in two contexts : by simulating oxides with a mixture of 2-coordinated and higher - coordinated sites, and by mapping site - bond percolation results onto a site model with mixed coordination number.   our results show that a conjectured power - law relationship between coordination number and site percolation threshold holds approximately if the coordination number is defined as the average number of connections available between high - coordinated sites, and suggest that the conjectured power - law relationship reflects a real phenomenon requiring further study.   the solution may be to modify the power - law relationship to be an implicit formula for percolation threshold, one that takes into account aspects of the lattice beyond spatial dimension and average coordination number.   _ keywords _ : percolation, lattices
we discuss two higgs doublet models with a softly - broken discrete @xmath0 symmery, where the mass matrix for charged - leptons is predicted as the diagonal form in the weak eigenbasis of lepton fields.   similar to an introduction of @xmath1 symmetry, the tree level flavor changing neutral current can be forbidden by imposing the @xmath0 symmetry to the model. under the @xmath0 symmetry,   there are four types of yukawa interactions depending on the @xmath0 charge assignment to right - handed fermions.   we find that extra higgs bosons can be muon and electron specific in one of four types of the yukawa interaction.   this property does not appear in any other two higgs doublet models with a softly - broken @xmath2 symmetry.   we discuss the phenomenology of the muon and electron specific higgs bosons at the large hadron collider ; namely we evaluate allowed parameter regions from the current higgs boson search data and discovery potential of such a higgs boson at the 14 tev run.
we construct the complete set of positive parity pentaquarks, which correspond in the quark model to @xmath0 states with one unit of orbital angular momentum @xmath1. in the large @xmath2 limit they fall into the @xmath3 and @xmath4 irreps ( towers ) of the contracted @xmath5 symmetry.   we derive predictions for the mass spectrum and the axial couplings of these states at leading order in @xmath6.   the strong decay width of the lowest - lying positive parity exotic state is of order @xmath7, such that this state is narrow in the large @xmath2 limit. replacing the antiquark with a heavy antiquark @xmath8,   the two towers become degenerate, split only by @xmath9 hyperfine interactions.   we obtain predictions for the strong decay widths of heavy pentaquarks to ordinary baryons and heavy @xmath10 mesons at leading order in @xmath6 and @xmath11.    * positive parity pentaquark towers in large @xmath2 qcd *    dan pirjol@xmath12 and carlos schat@xmath13 +
we investigate the characteristics of two dimensional melting in simple atomic systems via isobaric - isothermal ( @xmath0 ) and isochoric - isothermal ( @xmath1 ) molecular dynamics simulations with special focus on the effect of the range of the potential on the melting.   we find that the system with interatomic potential of longer range clearly exhibits a region ( in the @xmath2 plane ) of ( thermodynamically ) stable hexatic phase. on the other hand, the one with shorter range potential exhibits a first - order melting transition both in @xmath0 and @xmath1 ensembles.   melting of the system with intermediate range potential shows a hexatic - like feature near the melting transition in @xmath1 ensemble, but it undergoes an unstable hexatic - like phase during melting process in @xmath0 ensemble, which implies existence of a weakly first order transition.   the overall features represent a crossover from a continuous melting transition in the cases of longer - ranged potential to a discontinuous ( first order ) one in the systems with shorter and intermediate ranged potential.   we also calculate the binder cumulants as well as the susceptibility of the bond - orientational order parameter.
given two distributions @xmath0 and @xmath1 on the nonnegative integers we propose an algorithm to construct in- and out - degree sequences from samples of i.i.d.   observations from @xmath0 and @xmath1, respectively, that with high probability will be graphical, that is, from which a simple directed graph can be drawn.   we then analyze a directed version of the configuration model and show that, provided that @xmath0 and @xmath1 have finite variance, the probability of obtaining a simple graph is bounded away from zero as the number of nodes grows. we show that conditional on the resulting graph being simple, the in- and out - degree distributions are ( approximately ) @xmath0 and @xmath1 for large size graphs. moreover, when the degree distributions have only finite mean we show that the elimination of self - loops and multiple edges does not significantly change the degree distributions in the resulting simple graph.
recent years have witnessed several initiatives on enabling internet access to the next three billion people.   access to the internet necessarily translates to access to its services.   this means that the goal of providing internet access requires access to its critical service infrastructure, which are currently hosted in the cloud.   however, recent works have pointed out that the current cloud centric nature of the internet is a fundamental barrier for internet access in rural / remote areas as well as in developing regions.   it is important to explore ( low cost ) solutions such as micro cloud infrastructures that can provide services at the edge of the network ( potentially on demand ), right near the users.    in this paper, we present @xmath0- a preliminary idea of deploying a lightweight micro cloud infrastructure in the sky using indigenously built low cost drones, single board computers and lightweight operating system virtualization technologies.   our paper lays out the preliminary ideas on such a system that can be instantaneously deployed on demand.   we describe an initial design of the @xmath0and provide a preliminary evaluation of the proposed system mainly focussed on the scalability issues of supporting multiple services and users.
we have analyzed the archival _ xmm - newton _ data of the bright ultra - luminous x - ray source ( ulx ) m82 x-1 with an 105 ksec exposure when the source was in the steady state.   thanks to the high photon statistics from the large effective area and long exposure, we were able to discriminate different x - ray continuum spectral models. neither the standard accretion disk model ( where the radial dependency of the disk effective temperature is @xmath0 ) nor a power - law model gives a satisfactory fit.   in fact, observed curvature of the m82 x-1 spectrum was just between those of the two models.   when the exponent of the radial dependence ( @xmath1 in @xmath2 ) of the disk temperature is allowed to be free, we obtained @xmath3.   such a reduction of @xmath1 from the standard value 3/4 under extremely high mass accretion rates is predicted from the accretion disk theory as a consequence of the radial energy advection.   thus, the accretion disk in m82 x-1 is considered to be in the _ slim disk _ state, where an optically thick advection dominant accretion flow ( adaf ) is taking place.   we have applied a theoretical slim disk spectral model to m82 x-1, and estimated the black hole mass @xmath4.   we propose that m82 x-1 is a relatively massive stellar black hole which has been produced through evolution of an extremely massive star, shining at a super - eddington luminosity by several times the eddington limit.
we have used the _ submillimeter wave astronomy satellite _ to map the ground - state @xmath0 transition of ortho - h@xmath1oat 557 ghz in the orion molecular cloud.   h@xmath1o   emission was detected in orion over an angular extent of about 20, or nearly 3 pc.   the water emission is relatively weak, with line widths ( 36 km s@xmath2 ) and @xmath3 velocities ( 911 km s@xmath2 ) consistent with an origin in the cold gas of the molecular ridge.   we find that the ortho - h@xmath1oabundance relative to h@xmath1 in the extended gas in orion varies between 1 and 8@xmath4, with an average of 3@xmath4.   the absence of detectable narrow - line ortho - h@xmath5o  emission is used to set a @xmath6  upper limit on the relative ortho - h@xmath1o  abundance of 7@xmath4.
we briefly review some constraints for stellar models in various mass regimes and evolutionary stages as provided by observational data from spectroscopy to multi - wavelenghts photometry.   the accuracy of present generation of stellar models can be significantly improved only through an extensive comparison between theory and observations.
we have designed a realistic simulation of astronomical observing using a relatively low - cost commercial ccd camera and a microcontroller - based circuit that drives leds inside a light - tight box with time - varying intensities. as part of a laboratory experiment  , students can acquire sequences of images using the camera, and then perform data analysis using a language such as matlab or python to : ( a ) extract the intensity of the imaged leds, ( b ) perform basic calibrations on the time - series data, and ( c ) convert their data into the frequency domain where they can then identify the frequency structure.   the primary focus is on studying light curves produced by the pulsating white dwarf stars.   the exercise provides an introduction to ccd observing, a framework for teaching concepts in numerical data analysis and fourier techniques, and connections with the physics of white dwarf stars.   ( submitted to the american journal of physics. )
we present a monte carlo study of a lattice gas driven out of equilibrium by a local hopping bias.   sites can be empty or occupied by one of two types of particles, which are distinguished by their response to the hopping bias.   all particles interact via excluded volume and a nearest - neighbor attractive force.   the main result is a phase diagram with three phases : a homogeneous phase, and two distinct ordered phases.   continuous boundaries separate the homogeneous phase from the ordered phases, and a first - order line separates the two ordered phases.   the three lines merge in a nonequilibrium bicritical point.
this paper includes a reflection on the role of networks in the study of english language acquisition, as well as a collection of practical criteria to annotate free - speech corpora from children utterances. at the theoretical level  , the main claim of this paper is that syntactic networks should be interpreted as the outcome of the use of the syntactic machinery.   thus, the intrinsic features of such machinery are not accessible directly from ( known ) network properties.   rather, what one can see are the global patterns of its use and, thus, a global view of the power and organization of the underlying grammar. taking a look into more practical issues,   the paper examines how to build a net from the projection of syntactic relations.   recall that, as opposed to adult grammars, early - child language has not a well - defined concept of structure. to overcome such difficulty  , we develop a set of systematic criteria assuming constituency hierarchy and a grammar based on lexico - thematic relations. at the end, what we obtain is a well defined corpora annotation that enables us i ) to perform statistics on the size of structures and ii ) to build a network from syntactic relations over which we can perform the standard measures of complexity.   we also provide a detailed example..    keywords : syntax, complex networks, learning, computation
this paper describes an alternative method of charged hyperon reconstruction applicable to the lhcb experiment.   it extends the seminal work of the focus collaboration @xcite to the specific detector layout of lhcb and addresses the reconstruction ambiguities reported in their earlier work, leading to improvements in the reconstruction efficiency for the specific cases of and baryon decays to a charged meson and a @xmath0 baryon.   hyperon reconstruction, lhcb, kink
it has been alleged in several papers that the so called delayed continuous - time random walks ( dctrws ) provide a model for the one - dimensional telegraph equation at microscopic level.   this conclusion, being widespread now, is strange, since the telegraph equation describes phenomena with finite propagation speed, while the velocity of the motion of particles in the dctrws is infinite. in this paper   we investigate how accurate are the approximations to the dctrws provided by the telegraph equation.   we show that the diffusion equation, being the correct limit of the dctrws, gives better approximations in @xmath0 norm to the dctrws than the telegraph equation.   we conclude therefore that, first, the dctrws do not provide any correct microscopic interpretation of the one - dimensional telegraph equation, and second, the kinetic ( exact ) model of the telegraph equation is different from the model based on the dctrws.   pacs numbers : :    05.40.-a, 05.40.fb, 05.60.-k, 05.60.cd, 02.30.jr, 02.30.mv
in this communication a new algorithm is proposed to produce surrogates for pseudoperiodic time series. by imposing a few constraints on the noise components of pseudoperiodic data sets  , we devise an effective method to generate surrogates.   unlike other algorithms, this method properly copes with pseudoperiodic orbits contaminated with linear colored observational noise.   we will demonstrate the ability of this algorithm to distinguish chaotic orbits from pseudoperiodic orbits through simulation data sets from the rssler system.   as an example of application of this algorithm, we will also employ it to investigate a human electrocardiogram ( ecg ) record.
the one - dimensional totally asymmetric simple exclusion process ( tasep ) is considered.   we study the time evolution property of a tagged particle in the tasep with the step initial condition.   calculated is the multi - time joint distribution function of its position. using the relation of the dynamics of the tasep to the schur process, we show that the function is represented as the fredholm determinant.   we also study the scaling limit.   the universality of the largest eigenvalue in the random matrix theory is realized in the limit. when the hopping rates of all particles are the same, it is found that the joint distribution function converges to that of the airy process after the time at which the particle begins to move. on the other hand, when there are several particles with small hopping rate in front of a tagged particle, the limiting process changes at a certain time from the airy process to the process of the largest eigenvalue in the hermitian multi - matrix model with external sources.   
a view of the galactic bulge by means of their globular clusters is necessary for a deep understanding of its formation and evolution.   connections between the globular cluster and field star properties in terms of kinematics, orbits, chemical abundances and ages should shed light on different stellar population components.   based on spatial distribution and metallicity, we define a probable best list of bulge clusters, containing 43 entries  . future work on newly discovered objects, mostly from the vvv survey, is suggested.   these candidates might alleviate the issue of missing clusters on the far side of the bulge.   we discuss the reddening law affecting the cluster distances towards the center of the galaxy, and conclude that the most suitable total - to - selective absorption value appears to be r@xmath0=3.2, in agreement with recent analyses.   an update of elemental abundances for bulge clusters is provided.   globular clusters  galactic bulge   stellar populations  chemical composition
generating entanglement by simply cooling a system into a stationary state which is highly entangled has many advantages. schemes based on this idea are robust against parameter fluctuations, tolerate relatively large spontaneous decay rates, and achieve high fidelities independent of their initial state.   a possible implementation of this idea in atom - cavity systems has recently been proposed by kastoryano _   et al. _   [ phys.   rev.   lett.  * 106 *, 090502 ( 2011 ) ]. here   we propose an improved entanglement cooling scheme for two atoms inside an optical cavity which achieves higher fidelities for comparable single - atom cooperativity parameters @xmath0.   for example, we predict fidelities above @xmath1 even for @xmath0 as low as @xmath2 without requiring individual laser addressing and without having to detect photons.
the modeled performance of the alpha magnetic spectrometer ( ams ) as a high - energy ( 0.3 to 100 gev ) gamma - ray detector is described, and its gamma - ray astrophysics objectives are discussed.    * the gamma ray detection capabilities of the alpha magnetic spectrometer *    * r. battiston@xmath0, m. biasini@xmath0, e. fiandrini@xmath0, + j. petrakis@xmath1, and m.h.   salamon@xmath1 + *    @xmath0sezione infn and dipartimento di fisica, universit di perugia + @xmath1department of physics, university of utah +    * pacs, keywords : * 95.55.k, 98.54.c, 95.35.+d, 98.35.g ; high - energy gamma rays, blazars, neutralinos, gamma - ray background
the introductory physics series for bioscience students at the university of california, davis is described.   a central feature of the class is sense - making by the students during organized discussion / labs in which the students take part in peer - peer discussions, argumentation, and presentations of ideas.   differences in outcomes ( mcat scores and upper division gpas ) of students taking this class and students taking the standard physics series that this class supplanted are discussed.
we investigate the effects of neutrino - nucleus interactions ( the @xmath0-process ) on the production of iron - peak elements in population iii core - collapse supernovae.   the @xmath0-process and the following proton and neutron capture reactions produce odd-@xmath1 iron - peak elements in complete and incomplete si burning region.   this reaction sequence enhances the abundances of sc, mn, and co in the supernova ejecta.   the supernova explosion models of 15 @xmath2 and 25 @xmath2 stars with the @xmath0-process well reproduce the averaged mn / fe ratio observed in extremely metal - poor halo stars. in order to reproduce the observed mn / fe ratio,   the total neutrino energy in the supernovae should be @xmath3 ergs.   stronger neutrino irradiation and other production sites are necessary to reproduce the observed sc / fe and co / fe ratios, although these ratios increase by the @xmath0-process.
we present milliarcsecond - resolution radio very long baseline interferometry ( vlbi ) observations of the ultracool dwarfs tvlm51346546 ( m8.5 ) and 2mass j00361617 + 1821104 ( l3.5 ) in an attempt to detect sub - stellar companions via direct imaging or reflex motion.   both objects are known radio emitters with strong evidence for periodic emission on timescales of about 2 and 3 hours, respectively. using the inner seven vlba antennas  , we detect unresolved emission from tvlm51346546 on a scale of 2.5 mas ( @xmath0 stellar radii ), leading to a direct limit on the radio emission brightness temperature of @xmath1 k. however, with the higher spatial resolution afforded by the full vlba we find that the source appears to be marginally and asymmetrically resolved at a low s / n ratio, possibly indicating that tvlm51346546 is a binary with a projected separation of @xmath2 mas ( @xmath3 stellar radii ). using the 7-hr baseline of our observation   we find no astrometric shift in the position of tvlm51346546, with a @xmath4 limit of about 0.6 mas.   this is about 3 times larger than expected for an equal mass companion with a few - hour orbital period.   future monitoring of its position on a range of timescales will provide the required astrometric sensitivity to detect a planetary companion with a mass of @xmath5 m@xmath6 in a @xmath7 d ( @xmath8 au ) orbit, or with a mass of @xmath9 m@xmath6 in an orbit of @xmath10 yr ( @xmath11 au ).
we derive the proper motions, membership probabilities, and velocity dispersions of stars in the regions of the young ( @xmath0 myr - old ) open clusters ngc 2244 ( the central cluster in the monoceros r2 association ) and ngc 6530 ( the dominant cluster in the sgr ob1 association ) from photographic plate material obtained at shanghai astronomical observatory, with time baselines of 34 and 87 years, respectively. both clusters show clear evidence of mass segregation, but they do not exhibit any significant velocity - mass ( or, equivalently, a velocity - luminosity ) dependence.   this provides strong support for the suggestion that the observed mass segregation is  at least partially  due to the way in which star formation has proceeded in these complex star - forming regions ( `` primordial '' mass segregation ).   based on arguments related to the clusters published initial mass functions, in conjunction with our new measurements of their internal velocity dispersions ( @xmath1 and 8 km s@xmath2 for ngc 2244 and ngc 6530, respectively ), we provide strong arguments in favor of the dissolution of ngc 2244 on very short time - scales, while we speculate that ngc 6530 may be more stable against the effects of internal two - body relaxation. however, this latter object may well be destroyed by the strong tidal field prevalent at its location in the galactic plane in the direction of the galactic center.
based on a new approach to the detection of radio transients associated with extensive air showers induced by ultra high energy cosmic rays, the experimental apparatus codalema is in operation, measuring about 1 event per day corresponding to an energy threshold @xmath0  ev.   its performance makes possible for the first time the study of radio - signal features on an event - by - event basis.   the sampling of the magnitude of the electric field along a 600  meters axis is analyzed.   it shows that the electric field lateral spread is around 250  m ( fwhm ).   the possibility to determine with radio both arrival directions and shower core positions is discussed.   radio detection, ultra high energy cosmic rays 95.55.jz, 95.85.ry, 96.40.-z
we present two efficient quantum key distribution schemes over two different collective - noise channels.   the accepted hypothesis of collective noise is that photons travel inside a time window small compared to the variation of noise.   noiseless subspaces are made up of two bell states and the spatial degree of freedom is introduced to form two nonorthogonal bases.   although these protocols resort to entangled states for encoding the key bit, the receiver is only required to perform single - particle product measurements and there is no basis mismatch.   moreover, the detection is passive as the receiver does not switch his measurements between two conjugate measurement bases to get the key.
amorphous solids yield in strain - controlled protocols at a critical value of the strain. for larger strains the stress and energy display a generic complex serrated signal with elastic segments punctuated by sharp energy and stress plastic drops having a wide range of magnitudes.   here we provide a theory of the scaling properties of such serrated signals taking into account the system - size dependence.   we show that the statistics are not homogeneous - they separate sharply to a regime of ` small'and ` large'drops, each endowed with its own scaling properties.   a scaling theory is first derived solely by data analysis, showing a somewhat complex picture.   but after considering the physical interpretation one discovers that the scaling behavior and the scaling exponents are in fact very simple and universal.
mergers of two carbon - oxygen white dwarfs have long been suspected to be progenitors of type ia supernovae. here   we present our modifications to the cosmological smoothed particle hydrodynamics code gadget to apply it to stellar physics including but not limited to mergers of white dwarfs.   we demonstrate a new method to map a one - dimensional profile of an object in hydrostatic equilibrium to a stable particle distribution.   we use the code to study the effect of initial conditions and resolution on the properties of the merger of two white dwarfs. we compare mergers with approximate and exact binary initial conditions and find that exact binary initial conditions lead to a much more stable binary system but there is no difference in the properties of the actual merger.   in contrast, we find that resolution is a critical issue for simulations of white dwarf mergers.   carbon burning hotspots which may lead to a detonation in the so - called violent merger scenario emerge only in simulations with sufficient resolution but independent of the type of binary initial conditions.   we conclude that simulations of white dwarf mergers which attempt to investigate their potential for type ia supernovae should be carried out with at least @xmath0 particles.       stars : supernovae : general  hydrodynamics  binaries : close  methods : numerical
we address those puzzling experiments in underdoped high @xmath0 superconductors which have been associated with normal state  vortices " and show these data can be understood as deriving from preformed pairs with onset temperature @xmath1. for uncorrelated bosons in small magnetic fields, and arbitrary @xmath2, we present the exact contribution to _ all _ transport coefficients. in the overdoped regime   our results reduce to those of standard fluctuation theories ( @xmath3 ).   semi - quantitative agreement with nernst, ac and dc conductivity and diamagnetic measurements is quite reasonable.
we present a few  mode galerkin model for convection in binary fluid layers subject to an approximation to realistic horizontal boundary conditions at positive separation ratios.   the model exhibits convection patterns in form of rolls and squares.   the stable squares at onset develop into stable rolls at higher thermal driving. in between, a regime of a so - called crossroll structure is found.   the results of our few  mode model are in good agreement with both experiments and numerical multi  mode simulations.
in this work, the quantum confinement effect is proposed as the cause of the displacement of the vibrational spectrum of molecular groups that involve hydrogen bonds. in this approach   the hydrogen bond imposes a space barrier to hydrogen and constrains its oscillatory motion.   we studied the vibrational transitions through the morse potential, for the nh and oh molecular groups inside macromolecules in situation of confinement ( when hydrogen bonding is formed ) and non - confinement ( when there is no hydrogen bonding ).   the energies were obtained through the variational method with the trial wave functions obtained from supersymmetric quantum mechanics ( sqm ) formalism.   the results indicate that it is possible to distinguish the emission peaks related to the existence of the hydrogen bonds.   these analytical results were satisfactorily compared with experimental results obtained from infrared spectroscopy.   @xmath0 )     biblabel#1.
antal _ et al. _   [ phys. rev.   e * 72 *, 036121 ( 2005 ) ] have studied the balance dynamics on the social networks. in this paper,   based on the model proposed by antal _   et al. _  , we improve it and generalize the binary social networks to the ternary social networks. when the social networks get dynamically balanced, we obtain the distributions of each relation and the time needed for dynamic balance. besides, we study the self - organized criticality on the ternary social networks based on our model. for the ternary social networks evolving to the sensitive state, any small disturbance may result in an avalanche.   the occurrence of the avalanche satisfies the power - law form both spatially and temporally.   numerical results verify our theoretical expectations.
we have used n - body simulations for the milky way to investigate the kinematic and structural properties of the old metal - poor stellar halo in the barred inner region of the galaxy.   we find that the extrapolation of the density distribution for bulge rr lyrae stars, @xmath0, approximately matches the number density of rr lyrae in the nearby stellar halo.   we follow the evolution of such a tracer population through the formation and evolution of the bar and box / peanut bulge in the n - body model.   we find that its density distribution changes from oblate to triaxial, and that it acquires slow rotation in agreement with recent measurements.   the maximum radial velocity is @xmath1 km / s at @xmath2, and the velocity dispersion is @xmath3 km / s.   even though the simulated metal - poor halo in the bulge has a barred shape, just @xmath4 of the orbits follow the bar, and it does not trace the peanut / x structure. with these properties,   the rr lyrae population in the galactic bulge is consistent with being the inward extension of the galactic metal - poor stellar halo.       galaxy : bulge  galaxy : kinematics and dynamics  galaxy : structure galaxy : centre  methods : numerical
following established tradition, software engineering today is rooted in a conceptually centralized way of thinking.   the primary se artifact is a specification of a machine   a computational artifact  that would meet the ( elicited and ) stated requirements. therein lies a fundamental mismatch with ( open ) sociotechnical systems, which involve multiple autonomous social participants or _ principals _ who interact with each other to further their individual goals.   no central machine governs the behaviors of the various principals.   we introduce interaction - oriented software engineering ( iose ) as an approach expressly suited to the needs of open sociotechnical systems. in iose  , specifying a system amounts to specifying the interactions among the principals as _   iose reinterprets the classical software engineering principles of modularity, abstraction, separation of concerns, and encapsulation in a manner that accords with the realities of sociotechnical systems. to highlight the novelty of iose  , we show where well - known se methodologies, especially those that explicitly aim to address either sociotechnical systems or the modeling of interactions among autonomous principals, fail to satisfy the iose principles.       amit  k.  chopra : school of computing and communications, lancaster university, lancaster la1 4wa, united kingdom..   munindar  p.  singh : department of computer science, north carolina state university, raleigh, nc 27695 - 8206, usa.
at measurements of gamma - radiation spectra from ultra - relativistic electrons in periodic structures, pileup of events in the calorimeter may cause significant deviation of the detector signal from the classically evaluated spectrum. that requires appropriate resummation of multiphoton contributions.   we describe the resummation procedure for the photon spectral intensity and for the photon multiplicity spectrum, and apply it to the study of spectra of coherent radiation with an admixture of incoherent component.   impact of multiphoton effects on the shape of the radiation spectrum is investigated.   the limit of high photon multiplicity for coherent radiation is explored. a method for reconstruction of the underlying single - photon spectrum from the multiphoton one   is proposed.
as some of the first known objects to exist in the universe, lyman alpha emitting galaxies ( laes ) naturally draw a lot of interest. first discovered over a decade ago, they have allowed us to probe the early universe, as their strong emission line compensates for their faint continuum light. while initially thought to be indicative of the first galaxies forming in the universe, recent studies have shown them to be increasingly complex, as some fraction appear evolved, and many laes appear to be dusty, which one would not expect from primordial galaxies.   presently, much interest resides in discovering not only the highest redshift galaxies to constrain theories of reionization, but also pushing closer to home, as previous ground - based studies have only found laes at @xmath0 due to observational limitations. in this review talk   i will cover everything from the first theoretical predictions of laes, to their future prospects for study, including the hetdex survey here in texas.
we calculate the observable signatures of the first generation of stars at high redshift ( @xmath0 ). to determine the cosmic star   formation history, we use an extension of the press   schechter formalism for cold dark matter ( cdm ) cosmologies that incorporates gas pressure.   we calibrate the fraction of gas converted into stars to be 6% so as to reproduce the 1% solar c / h ratio observed in the intergalactic medium ( igm ) at @xmath1.    with this star   formation efficiency, we find that ngst would be able to image more than @xmath2 star clusters from high redshifts ( @xmath3 ) within its @xmath4 field of view. if stars occupy a region comparable to the virial radius of the cluster, then @xmath51% of these clusters could be resolved.   we calculate the expected number  flux relation and angular size distribution for these early star clusters.   we also describe the reionization of the igm due to the first generation of stars, and the consequent damping of the cmb anisotropies on small angular scales.   this damping could be detected on @xmath6 angular scales by map and planck.
this work presents a sound probabilistic method for enforcing adherence of the marginal probabilities of a multi - label model to automatically discovered deterministic relationships among labels.   in particular we focus on discovering two kinds of relationships among the labels.   the first one concerns pairwise positive entailment : pairs of labels, where the presence of one implies the presence of the other in all instances of a dataset.   the second concerns exclusion : sets of labels that do not coexist in the same instances of the dataset.   these relationships are represented with a bayesian network.   marginal probabilities are entered as soft evidence in the network and adjusted through probabilistic inference.   our approach offers robust improvements in mean average precision compared to the standard binary relavance approach across all 12 datasets involved in our experiments.   the discovery process helps interesting implicit knowledge to emerge, which could be useful in itself.
we propose a cipher similar to the one time pad and mceliece cipher based on a subband coding scheme.   the encoding process is an approximation to the one time pad encryption scheme.   we present results of numerical experiments which suggest that a brute force attack to the proposed scheme does not result in all possible plaintexts, as the one time pad does, but still the brute force attack does not compromise the system.   however, we demonstrate that the cipher is vulnerable to a chosen - plaintext attack.
we study pattern formation in a complex swift hohenberg equation with phase - sensitive ( parametric ) gain.   such an equation serves as a universal order parameter equation describing the onset of spontaneous oscillations in extended systems submitted to a kind of forcing dubbed rocking when the instability is towards long wavelengths.   applications include two - level lasers and photorefractive oscillators. under rocking,   the original continuous phase symmetry of the system is replaced by a discrete one, so that phase bistability emerges.   this leads to the spontaneous formation of phase - locked spatial structures like phase domains and dark - ring ( phase- ) cavity solitons.   stability of the homogeneous solutions is studied and numerical simulations are made covering all the dynamical regimes of the model, which turn out to be very rich.   formal derivations of the rocked complex swift - hohenberg equation, using multiple scale techniques, are given for the two - level laser and the photorefractive oscillator
adaptive populations such as those in financial markets and distributed control can be modeled by the minority game.   we consider how their dynamics depends on the agents initial preferences of strategies, when the agents use linear or quadratic payoff functions to evaluate their strategies.   we find that the fluctuations of the population making certain decisions ( the volatility ) depends on the diversity of the distribution of the initial preferences of strategies.   when the diversity decreases, more agents tend to adapt their strategies together. in systems with linear payoffs,   this results in dynamical transitions from vanishing volatility to a non - vanishing one. for low signal dimensions, the dynamical transitions for the different signals do not take place at the same critical diversity.   rather, a cascade of dynamical transitions takes place when the diversity is reduced.   in contrast, no phase transitions are found in systems with the quadratic payoffs.   instead, a basin boundary of attraction separates two groups of samples in the space of the agents decisions.   initial states inside this boundary converge to small volatility, while those outside diverge to a large one.   furthermore, when the preference distribution becomes more polarized, the dynamics becomes more erratic.   all the above results are supported by good agreement between simulations and theory.
1-qubit quantum states form a space called the three - dimensional bloch ball. to compute holevo capacity, voronoi diagrams in the bloch ball with respect to the quantum divergence   have been used as a powerful tool.   these diagrams basically treat mixed quantum states corresponding to points in the interior of the bloch ball. due to the existence of logarithm in the quantum divergence  , the diagrams are not defined on pure quantum states corresponding to points on the two - dimensional sphere.   this paper first defines the voronoi diagrams for pure quantum states on the bloch sphere by the fubini - study distance and the bures distance.   we also introduce other voronoi diagrams on the sphere obtained by taking a limit of voronoi diagrams for mixed quantum states by the quantum divergences in the bloch ball.   these diagrams are shown to be equivalent to the ordinary voronoi diagram on the sphere.
we present the results of mapping the planetary nebula ngc6369 using multiple long slit spectra taken with the ctio 1.5 m telescope. we create two dimensional emission line images from our spectra, and use these to derive fluxes for 17 lines, the h@xmath0/h@xmath1 extinction map, the  line ratio density map, and the  temperature map of the nebula.   we use our photoionization code constrained by these data to determine the distance, the ionizing star characteristics, and show that a clumpy hour - glass shape is the most likely three - dimensional structure for ngc6369. note that our knowledge of the nebular structure eliminates all uncertainties associated with classical distance determinations, and our method can be applied to _   any spatially resolved emission line nebula_. we use the central star, nebular emission line, and optical+ir luminosities to show that ngc6369 is matter bound, as about 70% of the lyman continuum flux escapes. using evolutionary tracks from @xcite we derive a central star mass of about 0.65m@xmath2.
we evaluate the fermionic casimir effect associated with a massive fermion confined within a planar @xmath0 dimensional slab - bag, on which mit bag model boundary conditions of standard type, along a single spatial direction, are imposed. a simple and effective method for adding up the zero - point energy eigenvalues, corresponding to a quantum field under the influence of arbitrary boundary conditions, imposed on the field on flat surfaces perpendicular to a chosen spatial direction, is proposed. using this procedure,   an analytic result is obtained, from which small and large fermion mass limits, valid for an arbitrary number of dimensions, are derived.   they match some known results in particular cases.   the method can be easily extended to other configurations.   @xmath1 e - mail : elizalde@ieec.fcr.es + @xmath2 e - mail : filadelf@if.ufrj.br + @xmath3 e - mail : tort@if.ufrj.br + @xmath4 present address : institut destudis espacials de catalunya ( ieec / csic ) edifici nexus 201, gran capit 2 - 4, 08034 barcelona, spain.   e - mail address : visit11@ieec.fcr.es
we have investigated random submonolayer films of @xmath0 transition metals on w(001 ). the tight - binding linear muffin - tin orbital method combined with the coherent potential approximation   was employed to calculate the electronic structure of the films.   we have estimated local magnetic moments and the stability of different magnetic structures, namely the ferromagnetic order, the disordered local moments and the non - magnetic state, by comparing the total energies of the corresponding systems.   it has been found that the magnetic moments of v and cr decrease and eventually disappear with decreasing coverage. on the other hand,   fe retains approximately the same magnetic moment throughout the whole concentration range from a single impurity to the monolayer coverage.   mn is an intermediate case between cr and fe since it is non - magnetic at very low coverages and ( ferro)magnetic otherwise.
finite - size scaling, finite - size corrections, and boundary effects for critical systems have attracted much attention in recent years. here   we derive exact finite - size corrections for the free energy @xmath0 and the specific heat @xmath1 of the critical ferromagnetic ising model on the @xmath2 square lattice with brascamp - kunz ( bk ) boundary conditions [ j. math. phys. *   15 *, 66 ( 1974 ) ] and compared such results with those under toroidal boundary conditions.   when the ratio @xmath3 is smaller than 1 the behaviors of finite - size corrections for @xmath1 are quite different for bk and toroidal boundary conditions ; when @xmath4 is larger than 3, finite - size corrections for @xmath1 in two boundary conditions approach the same values. in the limit @xmath5   we obtain the expansion of the free energy for infinitely long strip with bk boundary conditions.   our results are consistent with the conformal field theory prediction for the mixed boundary conditions by cardy [ nucl. phys.   * b 275 *, 200 ( 1986 ) ] although the definitions of boundary conditions in two cases are different in one side of the long strip.   l    0.2 cm    pacs numbers : 05.50+q, 75.10-b
we benchmark various available event generators in _ geant4 _ and _ egs5 _ in the light of ongoing projects for high angular - resolution pair - conversion telescopes at low energy.   we compare the distributions of key kinematic variables extracted from the geometry of the three final state particles.   we validate and use as reference an exact generator using the full 5d differential cross - section of the conversion process.   we focus in particular on the effect of the unmeasured recoiling nucleus on the angular resolution.   we show that for high resolution trackers, the choice of the generator affects the estimated resolution of the telescope.   we also show that the current available generator are unable to describe accurately a linearly polarised photon source.
we study resonances of nonlinear systems of differential equations, including but not limited to the equations of motion of a particle moving in a potential.   we use the calculus of variations to determine the minimal additive forcing function that induces a desired terminal response, such as an energy in the case of a physical system.   we include the additional constraint that only select degrees of freedom be forced, corresponding to a very general class of problems in which not all of the degrees of freedom in an experimental system are accessible to forcing.   we find that certain lagrange multipliers take on a fundamental physical role as the effective forcing experienced by the degrees of freedom which are not forced directly.   furthermore, we find that the product of the displacement of nearby trajectories and the effective total forcing function is a conserved quantity.   we demonstrate the efficacy of this methodology with several examples.
we present three new binary pulsars discovered during a search for pulsations in 56 unidentified mid - latitude egret @xmath0-ray error boxes with the parkes multibeam receiver.   timing observations of these sources is on - going with both the parkes and the green bank telescopes.   we discuss the place of these new systems in the population of binary pulsars and suggest that they are all somewhat atypical systems.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
this tutorial article introduces the physics of spin transfer torques in magnetic devices.   we provide an elementary discussion of the mechanism of spin transfer torque, and review the theoretical and experimental progress in this field.   our intention is to be accessible to beginning graduate students.   this is the introductory paper for a cluster of `` current perspectives '' articles on spin transfer torques published in volume * 320 * of the _ journal of magnetism and magnetic materials_. this article is meant to set the stage for the others which follow it in this cluster ; they focus in more depth on particularly interesting aspects of spin - torque physics and highlight unanswered questions that might be productive topics for future research.
ethane is expected to be the dominant photochemical product on titan s surface and, in the absence of a process that sequesters it from exposed surface reservoirs, a major constituent of its lakes and seas.   absorption of cassini s 2.2 cm radar by ligeia mare however suggests that this north polar sea is dominated by methane. in order to explain this apparent ethane deficiency  , we explore the possibility that ligeia mare is the visible part of an alkanofer that interacted with an underlying clathrate layer and investigate the influence of this interaction on an assumed initial ethane - methane mixture in the liquid phase.   we find that progressive liquid entrapment in clathrate allows the surface liquid reservoir to become methane - dominated for any initial ethane mole fraction below 0.75.   if interactions between alkanofers and clathrates are common on titan, this should lead to the emergence of many methane - dominated seas or lakes.   titan, titan, hydrology, titan, surface, titan, atmosphere
by means of a semiclassical analysis we show that the trace anomaly does not affect the cosmological constant.   we calculate the evolution of the hubble parameter in quasi de sitter spacetime, where the hubble parameter varies slowly in time, and in flrw spacetimes.   we show dynamically that a universe consisting of matter with a constant equation of state, a cosmological constant and the quantum trace anomaly evolves either to the classical de sitter attractor or to a quantum trace anomaly driven one.   there is no dynamical effect that influences the effective value of the cosmological constant.
competition between the kondo effect and ruderman - kittel - kasuya - yosida interaction in the two - impurity kondo problem can be phenomenologically described by the rasul - schlottmann spin model.   we revisit this model from the quantum entanglement perspective by calculating both the inter - impurity entanglement and the local kondo entanglement, the latter being the entanglement between a local magnetic impurity and its spatially nearby conduction electron. a groundstate phase diagram is derived and a discontinuous breakdown of the local kondo entanglement is found at the singular point, associated concomitantly with a jump in the inter - impurity entanglement.   an entanglement monogamy holds in the whole phase diagram.   our results identify the important role of the frustrated cross - coupling and demonstrate the local characteristic of the quantum phase transition in the two - impurity kondo problem.   the implications of these results for kondo lattices and quantum information processing are also briefly discussed.
observations of diffuse galactic gamma ray emission ( dge ) by the _ fermi _ large area telescope ( lat ) allow a detailed study of cosmic rays and the interstellar medium. however, diffuse emission models of the inner galaxy underpredict the fermi - lat data at energies above a few gev and hint at possible non - astrophysical sources including dark matter ( dm ) annihilations or decays.   we present a study of the possible emission components from dm using the high - resolution via lactea ii n - body simulation of a milky way - sized dm halo.   we generate full - sky maps of dm annihilation and decay signals that include modeling of the adiabatic contraction of the host density profile, sommerfeld - enhanced dm annihilations, @xmath0-wave annihilations, and decaying dm.   we compare our results with the dge models produced by the fermi - lat team over different sky regions, including the galactic center, high galactic latitudes, and the galactic anti - center.   this work provides possible smooth component templates of dm to fit the observational data.   the subhalo contributions can be considered to provide statistically meaningful templates, and demonstrate how spatial profiles are significantly modified according to different annihilation / decay scenarios.   we argue that a subhalo - based approach can help constrain the dm physics.
in this paper we build the structure equations and the integrable systems for a discrete centroaffine indefinite surface in @xmath0. at the same time  , some centroaffine invariants are obtained according to the structure equations. using these centroaffine invariants, we study the laplacian operator and the convexity of a discrete centroaffine indefinite surface.   furthermore, some interest examples are provided.    * msc 2000 : * 53a15.    *   key words : * centroaffine transformation, discrete surface, integrable systems.
we present @xmath0/cos high @xmath1 observations of the @xmath2 multi - phase absorber towards 3c  263.   the cos data shows absorption from ( ly-@xmath3 to ly-@xmath4 ),,,, and.   the in this absorber is detected in the @xmath5 spectrum along with,, and.   the low and intermediate ions are kinematically aligned with each other and and display narrow line widths of @xmath6 .   the   lines are kinematically offset by @xmath7   from the low ions and are a factor of @xmath8 broader.   all metal ions except and are consistent with an origin in gas photoionized by the extragalactic background radation.   the bulk of the observed is also traced by this photoionized medium.   the metallicity in this gas phase is z @xmath9  z@xmath10 with carbon having near - solar abundances.   the and favor an origin in collisionally ionized gas at @xmath11  k. the absorption associated with this warm absorber is a bla marginally detected in the cos spectrum.   this warm gas phase has a metallicity of  @xmath12  dex, and a total hydrogen column density of @xmath13   which is @xmath14  dex higher than what is traced by the photoionized gas.   simultaneous detection of, and blas in an absorber can be a strong diagnostic of gas with @xmath15  k corresponding to the _ warm _ phase of the whim or shock - heated gas in the extended halos of galaxies.
we present the results of numerical simulations of continuum - driven winds of stars that exceed the eddington limit and compare these against predictions from earlier analytical solutions.   our models are based on the assumption that the stellar atmosphere consists of clumped matter, where the individual clumps have a much larger optical thickness than the matter between the clumps.   this ` porosity'of the stellar atmosphere reduces the coupling between radiation and matter, since photons tend to escape through the more tenuous gas between the clumps.   this allows a star that formally exceeds the eddington limit to remain stable, yet produce a steady outflow from the region where the clumps become optically thin.   we have made a parameter study of wind models for a variety of input conditions in order to explore the properties of continuum - driven winds.   the results show that the numerical simulations reproduce quite closely the analytical scalings.   the mass loss rates produced in our models are much larger than can be achieved by line driving.   this makes continuum driving a good mechanism to explain the large mass loss and flow speeds of giant outbursts, as observed in @xmath0  carinae and other luminous blue variable ( lbv ) stars.   continuum driving may also be important in population iii stars, since line driving becomes ineffective at low metalicities.   we also explore the effect of photon tiring and the limits it places on the wind parameters.       hydrodynamics  methods : numerical  stars : mass loss  stars : winds, outflows
an efficient method to calculate tadpole diagrams is proposed.   its capability is demonstrated by analytically evaluating two four - loop tadpole diagrams of current interest in the literature, including their @xmath0 terms in @xmath1 space - time dimensions.   ,    quantum field theory, multi - loop calculations, tadpole diagrams    11.15.-q, 12.38.bx
emerging technologies with asymptotic zero power dissipation, such as quantum computing, require the logical operations to be done in a reversible manner.   in recent years, the problem of synthesizing boolean functions in the reversible logic domain has gained significant research attention.   the efficiency of the synthesis methods is measured in terms of quantum cost, gate cost, garbage lines, logic depth and speed of synthesis. in this paper  , we present a modification of the existing approaches based on exclusive sum - of - products ( esop ), which allows to explore the trade - off between quantum cost and garbage lines.   the proposed technique adds a new dimension to the reversible logic synthesis solutions.   we demonstrate by detailed experiments that controlled improvement in quantum cost and gate count by increasing garbage count can be achieved. in some cases, improved quantum cost and gate count compared to state - of - the - art synthesis methods   are reported.   furthermore, we propose a novel rule - based approach to achieve ancilla - free reversible logic synthesis starting from an esop formulation.
in this paper we present evidence suggesting that the absence or presence of hidden broad line regions ( hblrs ) in seyfert 2 galaxies is regulated by the rate at which matter accretes onto a central supermassive black hole, in units of eddington rate.   evidence is based on data from a subsample of type 2 agns extracted from the tran ( 2001 ) spectropolarimetric sample and made up of all those sources that also have good quality x - ray spectra available, and for which a bulge luminosity can be estimated.   we use the intrinsic ( i.e. unabsorbed ) x - ray luminosities of these sources and their black hole masses ( estimated by using the well known relationship between nuclear mass and bulge luminosity in galaxies ) to derive the nuclear accretion rate in units of eddington.   we find that virtually all hblr sources have accretion rate larger than a threshold value of @xmath0 ( in eddington units ), while non - hblr sources lie at @xmath1.   these data nicely fit predictions from a model proposed by nicastro ( 2000 ), in which the broad line regions ( blrs ) are formed by accretion disk instabilities occurring in proximity of the critical radius at which the disk changes from gas pressure dominated to radiation pressure dominated.   this radius diminishes with decreasing @xmath2 ; for low enough accretion rates ( and therefore luminosities ), the critical radius becomes smaller than the innermost stable orbit, and blrs can not form.
at low volume fraction, disordered arrangements of frictionless spheres are found in un   jammed states unable to support applied stresses, while at high volume fraction they are found in jammed states with mechanical strength. here   we show, focusing on the hard sphere zero pressure limit, that the transition between un - jammed and jammed states does not occur at a single value of the volume fraction, but in a whole volume fraction range. this result is obtained via the direct numerical construction of disordered jammed states with a volume fraction varying between two limits, @xmath0 and @xmath1.   we identify these limits with the random loose packing volume fraction @xmath2 and the random close packing volume fraction @xmath3 of frictionless spheres, respectively.
spectroscopy of nuclei in the mass range @xmath0 to @xmath1, participating in double beta decay processes are studied in the framework of the self - consistent deformed hartree - fock ( hf ) and angular momentum ( j ) projection model.   spectra of ground bands have been studied and compared with available experimental results for even - even parent and daughter as well as for intermediate odd - odd nuclei. to test the reliability of the wave functions we have also calculated the reduced e2 transition matrix elements, electric quadrupole moments and magnetic dipole moments for these nuclei.   the calculated results are compared with the experimental findings and substantial agreement is achieved.
we present results on spectroscopic observations of the fast - rotating active giant, obtained mainly with the esa - musicos spectrograph at the isaac newton telescope ( int ) in 1996 and 1997 and also with the aurlie spectrograph at the observatoire de haute provence ( ohp ) in 1997.   the profiles analysed are those of the balmer, h@xmath0  and h@xmath1, and d3 ( @xmath2 5876  ) lines.   we analyse the balmer line variability and phase behaviour.   we confirm these lines as highly variable, with excess emission that originates from extended structures and exhibits clear signs of rotational modulation.   we have described the line profiles for two distinct states of activity, using different modelling approaches.   similar techniques were applied to the d3 spectra.   a large flare event lasting several days was detected in both balmer lines and in the d3 line.   the energy released during this flare in h@xmath0  is of the order of 10@xmath3  erg, making it the largest h@xmath0  flare reported on a cool star.   our results confirm the extreme complexity of the circumstellar environment of fk comae.   the activity level of this star is quite variable demanding different approaches to the line profile analysis.
we have performed sph simulations for the response of the gaseous disks to the imposed potentials including those from bars and smbhs.   evolution of the nuclear regions of gaseous disks depends critically on the masses of smbhs as well as the sound speeds in the gas.   # 1 1.25 in.125 in.25 in
a theoretical approach for a non - perturbative dynamical description of two interacting atoms in an optical lattice potential is introduced.   the approach builds upon the stationary eigenstates found by a procedure described in grishkevich _   et al. _   [ phys.   rev.   a * 84 *, 062710 ( 2011 ) ].   it allows presently to treat any time - dependent external perturbation of the lattice potential up to quadratic order.   example calculations of the experimentally relevant cases of an acceleration of the lattice and the turning - on of an additional harmonic confinement are presented.
in an emergency situation, imitation of strategies of neighbours can lead to an order - disorder phase transition, where spatial clusters of pedestrians adopt the same strategy.   we assume that there are two strategies, cooperating and competitive, which correspond to a smaller or larger desired velocity.   the results of our simulations within the social force model indicate that the ordered phase can be detected as an increase of spatial order of positions of the pedestrians in the crowd.
the public goods game is one of the most famous models for studying the evolution of cooperation in sizable groups.   the multiplication factor in this game can characterize the investment return from the public good, which may be variable depending on the interactive environment in realistic situations. instead of using the same universal value,   here we consider that the multiplication factor in each group is updated based on the differences between the local and global interactive environments in the spatial public goods game, but meanwhile limited to within a certain range.   we find that the adaptive and bounded investment returns can significantly promote cooperation.   in particular, full cooperation can be achieved for high feedback strength when appropriate limitation is set for the investment return. also, we show that the fraction of cooperators in the whole population can become larger if the lower and upper limits of the multiplication factor are increased.   furthermore, in comparison to the traditionally spatial public goods game where the multiplication factor in each group is identical and fixed, we find that cooperation can be better promoted if the multiplication factor is constrained to adjust between one and the group size in our model.   our results highlight the importance of the locally adaptive and bounded investment returns for the emergence and dominance of cooperative behavior in structured populations.
the maximum synchrotron burnoff limit of 160 mev represents a fundamental limit to radiation resulting from electromagnetic particle acceleration in one - zone ideal plasmas. in magnetic reconnection, however, particle acceleration and radiation are decoupled because the electric field is larger than the magnetic field in the diffusion region.   we carry out two - dimensional particle - in - cell simulations to determine the extent to which magnetic reconnection can produce synchrotron radiation above the burnoff limit.   we use the test particle comparison ( tpc ) method to isolate the effects of cooling by comparing the trajectories and acceleration efficiencies of test particles incident on such a reconnection region with and without cooling them.   we find that the cooled and uncooled particle trajectories are typically similar during acceleration in the reconnection region, and derive an effective limit on particle acceleration that is inversely proportional to the average magnetic field experienced by the particle during acceleration. using the calculated distribution of this average magnetic field as a function of uncooled final particle energy, we find analytically that cooling does not affect power - law particle energy spectra except at energies far above the synchrotron burnoff limit. finally, we compare fully cooled and uncooled simulations of reconnection, confirming that the synchrotron burnoff limit does not produce a cutoff in the particle energy spectrum.   our results indicate that the tpc method accurately predicts the effects of cooling on particle acceleration in relativistic reconnection, and that even far above the burnoff limit, the synchrotron energy of radiation produced in reconnection is not limited by cooling.
we perform spherically - symmetric general - relativistic simulations of core collapse and the postbounce preexplosion phase in 32 presupernova stellar models of solar metallicity with zero - age - main - sequence masses of @xmath0 to @xmath1. using energy - dependent three - species neutrino transport in the two - moment approximation with an analytic closure,   we show that the emitted neutrino luminosities and spectra follow very systematic trends that are correlated with the compactness ( @xmath2 ) of the progenitor star s inner regions via the accretion rate in the preexplosion phase.   we find that these qualitative trends depend only weakly on the nuclear equation of state, but quantitative observational statements will require independent constraints on the equation of state and the rotation rate of the core as well as a more complete understanding of neutrino oscillations. we investigate the simulated response of water cherenkov detectors to the electron antineutrino fluxes from our models and find that the large statistics of a galactic core collapse event may allow robust conclusions on the inner structure of the progenitor star.
we study the binary fraction of the globular cluster m10 ( ngc  6254 ) as a function of radius from the cluster core to the outskirts, by means of a quantitative analysis of the color distribution of stars relative to the fiducial main sequence. by taking advantage of two data - sets, acquired with the advanced camera for survey and the wide field planetary camera 2 on board the hubble space telescope,   we have studied both the core and the external regions of the cluster.   the binary fraction is found to decrease from @xmath0 within the core, to @xmath1 in a region between 1 and 2 half - mass radii from the cluster centre.   such a trend and the derived values are in agreement with previous results obtained in clusters of comparable total magnitude.   the estimated binary fraction is sufficient to account for the suppression of mass segregation observed in m10, without any need to invoke the presence of an intermediate - mass black hole in its centre.
we study the viability of observation of cpt violation in the top sector at future colliders.   we show possible studies and different estimates for hadronic and linear colliders.   in particular, we will present current constraints for tevatron and prospects for the lhc and the ilc.
clumping in hot star winds can significantly affect estimates of mass - loss rates, the inferred evolution of the star and the environmental impact of the wind.   a hydrodynamical simulation of a colliding winds binary ( cwb ) with clumpy winds reveals that the clumps are rapidly destroyed after passing through the confining shocks of the wind - wind collision region ( wcr ) for reasonable parameters of the clumps if the flow in the wcr is adiabatic. despite large density and temperature fluctuations in the post - shock gas, the overall effect of the interaction   is to smooth the existing structure in the winds. averaged over the entire interaction region,   the resulting x - ray emission is very similar to that from the collision of smooth winds.   the insensitivity of the x - ray emission to clumping suggests it is an excellent diagnostic of the stellar mass - loss rates ( @xmath0 ) in wide cwbs, and may prove to be a useful addition to existing techniques for deriving @xmath0, many of which are extremely sensitive to clumping.   clumpy winds also have implications for a variety of phenomena at the wcr : particle acceleration may occur _ throughout _ the wcr due to supersonic mhd turbulence, re - acceleration at multiple shocks, and re - connection ; a statistical description of the properties of the wcr may be required for studies of non - equilibrium ionization and the rate of electron heating ; and the physical mixing of the two winds will be enhanced, as seems necessary to trigger dust formation.
we propose to detect quadrupole interactions of neutral ultra - cold atoms via their induced mean - field shift.   we consider a mott insulator state of spin - polarized atoms in a two - dimensional optical square lattice.   the quadrupole moments of the atoms are aligned by an external magnetic field.   as the alignment angle is varied, the mean - field shift shows a characteristic angular dependence, which constitutes the defining signature of the quadrupole interaction. for the @xmath0 states of yb and sr atoms  , we find a frequency shift of the order of tens of hertz, which can be realistically detected in experiment with current technology.   we compare our results to the mean - field shift of a spin - polarized quasi-2d fermi gas in continuum.
typical properties of glassy materials are shown to be captured by a mean - field free - volume theory.   relaxation processes are supposed to be free - volume activated, and different entropy barriers are associated with density relaxation and shear motion.   free - volume time logarithmic relaxation, kohlrausch - williams - watts, and power law viscosity result from the non - linear dynamics of spatially averaged quantities.   the exponents associated with these phenomena are related to a single parameter of the theory.   the theory also accounts for coexistence of jamming transitions and non - linear rheology.
the discovery of transiting `` super - earths '' with inflated radii and known masses such as kepler-11b - f, gj 1214b and 55 cnc e, indicates that these exoplanets did not lose their nebula - captured hydrogen - rich, degassed or impact - delivered protoatmospheres by atmospheric escape processes. because hydrodynamic blow - off of atmospheric hydrogen atoms is the most efficient atmospheric escape process we apply a time - dependent numerical algorithm which is able to solve the system of 1-d fluid equations for mass, momentum, and energy conservation to investigate the criteria under which `` super - earths '' with hydrogen - dominated upper atmospheres can experience hydrodynamic expansion by heating of the stellar xuv ( soft x - rays and extreme ultraviolet ) radiation and thermal escape via blow - off. depending on orbit location, xuv flux, heating efficiency and the planet s mean density our results indicate that the upper atmospheres of all `` super - earths '' can expand to large distances, so that besides of kepler-11c all of them experience atmospheric mass - loss due to roche lobe overflow.   the atmospheric mass - loss of the studied `` super - earths '' is one to two orders of magnitude lower compared to that of `` hot jupiters '' such as hd 209458b, so that one can expect that these exoplanets can not lose their hydrogen - envelopes during their remaining lifetimes.       planets and satellites : atmospheres  planets and satellites : physical evolution   ultraviolet : planetary systems  stars : ultraviolet  hydrodynamics
recently quantum _ battle of the sexes game _ has been studied by luca marinatto and tullio weber. yet   some important problems exist in their scheme. here   we propose a new scheme to quantize _ battle of the sexes game _, and this scheme will truly remove the dilemma that exists in the classical form of the game.
two of the most attractive spectral windows for spectropolarimetric investigations of the physical properties of the plasma structures in the solar chromosphere and corona are the ones provided by the spectral lines of the he i 10830   and 5876   ( or d@xmath0 ) multiplets, whose polarization signals are sensitive to the hanle and zeeman effects. however, in order to be able to carry out reliable diagnostics, it is crucial to have a good physical understanding of the sensitivity of the observed spectral line radiation to the various competing driving mechanisms. here   we report a series of off - the - limb non - lte calculations of the he i d@xmath0 and 10830   emission profiles, focusing our investigation on their sensitivity to the euv coronal irradiation and the model atmosphere used in the calculations.   we show in particular that the intensity ratio of the blue to the red components in the emission profiles of the he i 10830   multiplet turns out to be a good candidate as a diagnostic tool for the coronal irradiance.   measurements of this observable as a function of the distance to the limb and its confrontation with radiative transfer modeling might give us valuable information on the physical properties of the solar atmosphere and on the amount of euv radiation at relevant wavelengths penetrating the chromosphere from above.
we present data from _ integral _ and _ bepposax _ satellites showing spectral state transitions of the neutron - star, atoll - type, low - mass x - ray binary 4u  170544.   its energy spectrum can be described as the sum of one or two blackbody components, a 6.4-kev fe line, and a component due to thermal comptonization. in addition, and for the first time in this source, we find a strong signature of compton reflection, presumably due to illumination of the optically - thick accretion disk by the comptonization spectrum.   the two blackbody components, which the soft - state data require, presumably arise from both the disk and the neutron - star surface.   the comptonization probably takes place in a hot inner flow irradiated by some of the blackbody photons.   the spectral transitions are shown to be associated with variations in the bolometric luminosity, most likely proportional to the accretion rate.   indipendentely from the spectral state, we also see changes in the temperature of the comptonizing electrons and the strength of compton reflection.
we propose a @xmath0-decay experiment based on a sample of ultracold atomic tritium.   these initial conditions enable detection of the helium ion in coincidence with the @xmath0.   we construct a two - dimensional fit incorporating both the shape of the @xmath0-spectrum and the direct reconstruction of the neutrino mass peak.   we present simulation results of the feasible limits on the neutrino mass achievable in this new type of tritium @xmath0-decay experiment.
the level density and @xmath0-ray strength function ( @xmath0sf ) of @xmath1pu have been measured in the quasi - continuum using the oslo method.   excited states in @xmath1pu were populated using the @xmath2pu@xmath3 reaction.   the level density closely follows the constant - temperature level density formula for excitation energies above the pairing gap.   the @xmath0sf displays a double - humped resonance at low energy as also seen in previous investigations of actinide isotopes.   the structure is interpreted as the scissors resonance and has a centroid of @xmath4  mev and a total strength of @xmath5  @xmath6, which is in excellent agreement with sum - rule estimates.   the measured level density and @xmath0sf were used to calculate the @xmath2pu@xmath7 cross section in a neutron energy range for which there were previously no measured data.
we update the analytical estimate of the final spin of a coalescing black - hole binary derived within the effective - one - body ( eob ) approach.   we consider unequal - mass non - spinning black - hole binaries.   it is found that a more complete account of relevant physical effects ( higher post - newtonian accuracy, ringdown losses ) allows the _ analytical _ eob estimate to `` converge towards '' the recently obtained _ numerical _ results within @xmath0.   this agreement illustrates the ability of the eob approach to capture the essential physics of coalescing black - hole binaries.   our analytical approach allows one to estimate the final spin of the black hole formed by coalescing binaries in a mass range ( @xmath1 ) which is not presently covered by numerical simulations.
the behavior of persistent current in a mesoscopic cylinder threaded by an aharonov - bohm flux @xmath0 is carefully investigated within a hartree - fock mean field approach.   we examine the combined effect of second - neighbor hopping integral and hubbard correlation on the enhancement of persistent current in presence of disorder. a significant change in current amplitude   is observed compared to the traditional nearest - neighbor hopping model and the current amplitude becomes quite comparable to experimental realizations.   our analysis is found to exhibit several interesting results which have so far remained unaddressed.
on 2007 october 29 the outbursting comet 17p / holmes passed within 0.79  of a background star.   we recorded the event using optical, narrowband photometry and detect a 3% to 4% dip in stellar brightness bracketing the time of closest approach to the comet nucleus.   the detected dimming implies an optical depth @xmath0 at 1.5  from the nucleus and an optical depth towards the nucleus center @xmath1. at the time of our observations,   the coma was optically thick only within @xmath2 from the nucleus. by combining the measured extinction and the scattered light from the coma   we estimate a dust red geometric albedo @xmath3 at @xmath4 phase angle.   our measurements place the most stringent constraints on the extinction optical depth of any cometary coma.
we study the kinematics of ridge lines on the pc - scale jet of the active galactic nucleus bl lac.   we show that the ridge lines display transverse patterns that move superluminally downstream, and that the moving patterns are analogous to waves on a whip.   their apparent speeds @xmath0 ( units of @xmath1 ) range from 3.9 to 13.5, corresponding to @xmath2 in the galaxy frame.   we show that the magnetic field in the jet is well - ordered with a strong transverse component, and assume that it is helical and that the transverse patterns are alfvn waves propagating downstream on the longitudinal component of the magnetic field.   the wave - induced transverse speed of the jet is non - relativistic ( @xmath3 ). in 2010   the wave activity subsided and the jet then displayed a mild wiggle that had a complex oscillatory behaviour.   the alfvn waves appear to be excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking the handle. a simple model of the system with plasma sound speed @xmath4 and apparent speed of a slow mhd wave @xmath5 yields lorentz factor of the beam @xmath6, pitch angle of the helix ( in the beam frame ) @xmath7, alfvn speed @xmath8, and magnetosonic mach number @xmath9.   this describes a plasma in which the magnetic field is dominant and in a rather tight helix, and alfvn waves are responsible for the moving transverse patterns.
it has been almost one hundred years since einstein formulated his special theory of relativity in 1905.   he showed that the basic space - time symmetry is dictated by the lorentz group.   it is shown that this group of lorentz transformations is not only applicable to special relativity, but also constitutes the scientific language for optical sciences.   it is noted that coherent and squeezed states of light are representations of the lorentz group.   the lorentz group is also the basic underlying language for classical ray optics, including polarization optics, interferometers, the poincare sphere, one - lens optics, multi - lens optics, laser cavities, as well multilayer optics.   * lorentz group in ray optics *    sibel bakal + department of physics, middle east technical university, + 06531 ankara, turkey    elena georgieva + science systems and applications, inc., lanham, md 20771, u.s.a., and + national aeronautics and space administration, + goddard space flight center, laser and electro - optics branch, + code 554, greenbelt, maryland 20771, u.s.a.    y. s. kim + department of physics, university of maryland, + college park, maryland 20742, u.s.a.   +    marilyn e. noz + department of radiology, new york university, new york, new york 10016, u.s.a.
the momentum distribution is one of the most important quantities which provides information about interactions in many - body systems. at the same time it is a quantity that can easily be accessed in experiments on ultracold atoms. in this paper  , we consider mixtures of light and heavy fermionic atoms in an optical lattice described effectively by the falicov - kimball model. using a monte carlo method, we study how different ordered density - wave phases can be detected by measurement of the momentum distribution of the light atoms.   we also demonstrate that ordered phases can be seen in bragg scattering experiments.   our results indicate that the main factor that determines the momentum distribution of the light atoms is the trap confinement. on the other hand,   the pattern formed by the heavy atoms seen in the bragg scattering experiments is very sensitive to the temperature and possibly can be used in low - temperature thermometry.
we report the details and revised analysis of an experiment to measure the specific heat of helium with subnanokelvin temperature resolution near the lambda point.   the measurements were made at the vapor pressure spanning the region from 22 mk below the superfluid transition to 4 @xmath0k above.   the experiment was performed in earth orbit to reduce the rounding of the transition caused by gravitationally induced pressure gradients on earth.   specific heat measurements were made deep in the asymptotic region to within 2 nk of the transition.   no evidence of rounding was found to this resolution.   the optimum value of the critical exponent describing the specific heat singularity was found to be @xmath1.   this is bracketed by two recent estimates based on renormalization group techniques, but is slightly outside the range of the error of the most recent result.   the ratio of the coefficients of the leading order singularity on the two sides of the transition is a@xmath2/a@xmath3@xmath4, which agrees well with a recent estimate. by combining the specific heat and superfluid density exponents a test of the josephson scaling relation   can be made.   excellent agreement is found based on high precision measurements of the superfluid density made elsewhere.   these results represent the most precise tests of theoretical predictions for critical phenomena to date.
in this paper we continue previous efforts in the literature to determine phenomenological values for the gluon mass by confronting theoretical results obtained in a theory of massive gluons with experimental values or results directly referring to the nontrivial structure of the yang - mills vacuum, e.g. to the presence of the gluon condensate.   the decays of heavy quarkonia into @xmath0 gluons and @xmath1 gluons + photon are considered in detail as well as the correlators of the electromagnetic current and the scalar glueball current.   based on the analysis for the latter quantities a value for the gluon mass in the range of 500 - 600 mev is estimated from the standard svz - value of the gluon condensate.   hd   thep9647 + hep - ph/9611250 +     +    * gluon - mass effects in quarkonia decays, + @xmath2 annihilation and the scalar glueball current * + jue - ping liu + _ department of physics, wuhan university _ + _ wuhan / hubei 430072, p.r. of china _   + werner wetzel +   _ institut fr theoretische physik, universitt heidelberg _ + _ philosophenweg 16, d-69120 heidelberg, germany _ + november 4, 1996 +
_ we discuss how the conditions at high redshift differ from those at low redshift, and what the impact is on the galaxy population.   we focus in particular on the role of gaseous dissipation and its impact on sustaining high star formation rates as well as on driving star - bursts in mergers.   gas accretion onto galaxies at high redshifts occurs on a halo dynamical time allowing for very efficiently sustained star formation.   in addition cold accretion flows are able to drive turbulence in high redshift disks at the level observed if at least @xmath0 of the accretion energy is converted into random motion in the gaseous disk. in general   we find that the fraction of gas involved in galaxy mergers is a strong function of time and increases with redshift.   a model combining the role of dissipation during mergers and continued infall of satellite galaxies allows to reproduce the observed size - evolution of early - type galaxies with redshift.   furthermore we investigate how the evolution of the faint - end of the luminosity function can be explained in terms of the evolution of the underlying dark matter evolution.   _    * modeling the high - z universe : + probing galaxy formation * + sadegh khochfar + max - planck - institute for extraterrestrial physics + giessenbachstrasse, d-85748 garching, germany + sadeghk@mpe.mpg.de, http://www.mpe.mpg.de/  sadeghk/
we compare the stellar structure of the isolated, local group dwarf galaxy pegasus ( ddo216 ) with low resolution hi maps from @xcite.   our comparison reveals that pegasus displays the characteristic morphology of ram pressure stripping ; in particular, the hi has a `` cometary '' appearance which is not reflected in the regular, elliptical distribution of the stars. this is the first time this phenomenon has been observed in an isolated local group galaxy.   the density of the medium required to ram pressure strip pegasus is at least @xmath0@xmath1.   we conclude that this is strong evidence for an inter - galactic medium associated with the local group.
we discovered fine - scale structure within the scattering disk of psr  b0329 + 54 in observations with the _ radioastron _  ground - space radio interferometer. here  , we describe this phenomenon, characterize it with averages and correlation functions, and interpret it as the result of decorrelation of the impulse - response function of interstellar scattering between the widely - separated antennas.   this instrument included the 10-m space radio telescope, the 110-m green bank telescope, the @xmath0-m westerbork synthesis radio telescope, and the 64-m kalyazin radio telescope.   the observations were performed at 324 mhz, on baselines of up to 235,000  km in november  2012 and january  2014. in the delay domain, on long baselines   the interferometric visibility consists of many discrete spikes within a limited range of delays. on short baselines   it consists of a sharp spike surrounded by lower spikes.   the average envelope of correlations of the visibility function show two exponential scales, with characteristic delays of @xmath1 and @xmath2, indicating the presence of two scales of scattering in the interstellar medium.   these two scales are present in the pulse - broadening function.   the longer scale contains 0.38 times the scattered power of the shorter one.   we suggest that the longer tail arises from highly - scattered paths, possibly from anisotropic scattering or from substructure at large angles.
we present gas kinematics based on the  @xmath05007 line and their connection to galaxy gravitational potential, active galactic nucleus ( agn ) energetics, and star formation, using a large sample of @xmath1110,000 agns and star - forming ( sf ) galaxies at z@xmath20.3.   gas and stellar velocity dispersions are comparable to each other in sf galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. in contrast, agns clearly show non - gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. the   velocity - velocity dispersion ( vvd ) diagram dramatically expands toward high values as a function of agn luminosity, implying that the outflows are agn - driven, while sf galaxies do not show such a trend.   we find that the fraction of agns with a signature of outflow kinematics, steeply increases with agn luminosity and eddington ratio.   in particular, the majority of luminous agns presents strong non - gravitational kinematics in the   profile.   agns with strong outflow signatures show on average similar specific star formation rate ( ssfr ) to that of starforming galaxies.   in contrast, agns with weak or no outflows have an order of magnitude lower ssfr, suggesting that agns with current strong outflows do now show any negative agn feedback and that it may take the order of a dynamical time to impact on star formation over galactic scales.
the finite temperature effective potential in the 2 + 1 dimensional nambu - jona - lasinio model is constructed up to the next to leading order in the large @xmath0 expansion, where @xmath0 is the number of flavors in the model.   the distinctive feature of the analysis is an inclusion of an additional scalar field, which allows us to circumvent the well known, and otherwise unavoidable problem with the imaginary contribution to the effective potential. in accordance with the mermin - wagner - coleman theorem, applied to the dimensionally reduced subsystem of the zero matsubara modes of the composite boson fields, the finite temperature effective potential reveals a global minimum at the zero of the composite order parameter   this allows us to conclude that the continuous global symmetry of the njl model is not broken for any arbitrarily small, finite temperature.
for the last three years we have performed a survey for young ( @xmath0 gyrs ) giant planets around nearby white dwarfs with hst, spitzer, and vlt.   direct hst / nicmos imaging of the seven white dwarfs in the hyades gave no evidence for companions down to about 10 jupiter masses and separations larger than 0.5 arcsec ( @xmath125au ), while vlt / naco observations revealed a putative companion to a field white dwarf.   second epoch observations with sinfoni on the vlt, however, showed that it is most probably a background star.   with irac on spitzer we also found no indications of cool, very low mass companions in our sample of field white dwarfs.   the implications of these non - detections are briefly discussed.
screening is one of the fundamental concepts in solid state physics.   it has a great impact on the electronic properties of graphene where huge mobilities were observed in spite of the large concentration of charged impurities.   while static screening has successfully explained dc mobilities, screening properties can be significantly changed at infrared or optical frequencies. in this paper   we discuss the influence of dynamical screening on the optical absorption of graphene and other 2d electron systems like metallic monolayers.   this research is motivated by recent experimental results which pointed out that graphene plasmon linewidths and optical scattering rates can be much larger than scattering rates determined by dc mobilities.   specifically we discuss a process where a photon incident on a graphene plane can excite a plasmon by scattering from an impurity, or surface optical phonon of the substrate.
we study the fano effect and the visibility of the aharonov - bohm oscillations for a mesoscopic interferometer with an embedded quantum dot in the presence of a nearby second dot. when the electron - electron interaction between the two dots is considered the nearby dot acts as a charge detector.   we compute the currents through the interferometer and detector within the keldysh formalism and the self - energy of the non - equilibrium green functions is found up to the second order in the interaction strength.   the current formula contains a correction to the landauer - bttiker formula.   its contribution to transport and dephasing is discussed. as the bias applied on the detector   is increased, the amplitude of both the fano resonance and aharonov - bohm oscillations are considerably reduced due to controlled dephasing.   this result is explained by analyzing the behavior of the imaginary part of the self - energy as a function of energy and bias.   we investigate as well the role of the ring - dot coupling.   our theoretical results are consistent to the experimental observation of buks _ et al.   _ .
we consider the nonlinear energy conditions and their quantum extensions.   these new energy conditions behave much better than the usual pointwise energy conditions in the presence of semiclassical quantum effects.   analogous quantum extensions for the linear energy conditions are not always satisfied as one enters the quantum realm, but they can be used to constrain the violation of the classical conditions.   thus, the existence of wormholes supported by a fluid which violates the null energy condition in a controlled way is of particular interest.
a nonlocal coupling mechanism to directly transfer the energy from large - scale magnetohydrodynamic(mhd ) alfvn waves to small - scale kinetic alfvn waves is presented.   it is shown that the interaction between a mhd alfvn wave and a reversely propagating kinetic alfvn wave can generate another kinetic alfvn wave, and this interaction exists in the plasmas where the thermal to magnetic pressure ratio is larger than the electron to ion mass ratio.   the proposed nonlocal interaction may have a potential application to account for the observed electron scale kinetic alfvn waves in the solar wind and solar corona plasmas.
we present a diagrammatic real - time approach to adiabatic pumping of electrons through interacting quantum dots. performing a systematic perturbation expansion in the tunnel - coupling strength,   we compute the charge pumped through a single - level quantum dot per pumping cycle.   the combination of coulomb interaction and quantum fluctuations, accounted for in contributions of higher order in the tunnel coupling, modifies the pumping characteristics via an interaction - dependent renormalization of the quantum - dot level.   the latter is even responsible for the _ dominant _ contribution to the pumped charge when pumping via time - dependent tunnel - coupling strengths.
we show that the @xmath0gev diphoton excess can be explained by introducing vector - like quarks and hidden fermions charged under a hidden u(1 ) gauge symmetry, which has a relatively large coupling constant as well as a significant kinetic mixing with u(1)@xmath1. with the large kinetic mixing,   the standard model gauge couplings unify around @xmath2gev, suggesting the grand unified theory without too rapid proton decay.   our scenario predicts events with a photon and missing transverse momentum, and its cross section is related to that for the diphoton excess through the kinetic mixing.   we also discuss other possible collider signatures and cosmology, including various ways to evade constraints on exotic stable charged particles. in some cases where the @xmath0gev diphoton excess is due to diaxion decays, our scenario also predicts triphoton and tetraphoton signals.   c  u v   # 1#2 ( ) # 1#2#3 ( ) ^#3    tu-1021, ipmu16 - 0058 +.75 in     * diphoton excess from hidden u(1 ) gauge symmetry with large kinetic mixing *   .75 in    fuminobu takahashi@xmath3, masaki yamada@xmath4 and norimi yokozaki@xmath4    0.25 in        .5 in
we look into the inner structure of a two - dimensional dilatonic evaporating black hole. we establish and employ the homogenous approximation for the black - hole interior.   the field equations admit two types of singularities, and their local asymptotic structure is investigated.   one of these singularities is found to develop, as a spacelike singularity, inside the black hole.   we then study the internal structure of the evaporating black hole from the horizon to the singularity.
we employ density - functional theory ( dft ) in the generalized gradient approximation ( gga ) and its extensions gga+@xmath0 and gga+gutzwiller to calculate the magnetic exchange couplings between pairs of mn ions substituting cd in a cdte crystal at very small doping.   dft(gga ) overestimates the exchange couplings by a factor of three because it underestimates the charge - transfer gap in mn - doped ii - vi semiconductors.   fixing the nearest - neighbor coupling @xmath1 to its experimental value in gga+@xmath0, in gga+gutzwiller, or by a simple scaling of the dft(gga ) results provides acceptable values for the exchange couplings at 2nd, 3rd, and 4th neighbor distances in cd(mn)te, zn(mn)te, zn(mn)se, and zn(mn)s.   in particular, we recover the experimentally observed relation @xmath2.   the filling of the mn 3@xmath3-shell is not integer which puts the underlying heisenberg description into question.   however, using a few - ion toy model the picture of a slightly extended local moment emerges so that an integer @xmath4-shell filling is not a prerequisite for equidistant magnetization plateaus, as seen in experiment.
we introduce the notion of a tits arrangement on a convex open cone as a special case of ( infinite ) simplicial arrangements.   such an object carries a simplicial structure similar to the geometric representation of coxeter groups.   the standard constructions of subarrangements and restrictions, which are known in the case of finite hyperplane arrangements, work as well in this more general setting.
the mobility of a charged projectile in a strongly coupled dusty plasma is simulated.   a net force @xmath0, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility - limited velocity @xmath1. the mobility @xmath2 of the projectile s motion is obtained.   two regimes depending on @xmath0 are identified. in the high force regime, @xmath3, and   the scattering cross section @xmath4 diminishes as @xmath5.   results for @xmath4 are compared with those for a weakly coupled plasma and for two - body collisions in a yukawa potential.   the simulation parameters are based on microgravity plasma experiments.
using photometry and spectroscopy of 144,609 galaxies from the sloan digital sky survey, we present bivariate distributions of pairs of seven galaxy properties : four optical colors, surface brightness, radial profile shape as measured by the srsic  index, and absolute magnitude.   in addition, we present the dependence of local galaxy density ( smoothed on 8 @xmath0 mpc scales ) on all of these properties.   several classic, well - known relations among galaxy properties are evident at extremely high signal - to - noise ratio : the color  color relations of galaxies, the color  magnitude relations, the magnitude  surface brightness relation, and the dependence of density on color and absolute magnitude.   we show that most of the @xmath1-band luminosity density in the universe is in the absolute magnitude and surface brightness ranges used : @xmath2 and @xmath3 in @xmath4 ( the notation @xmath5 represents the @xmath6 band shifted blueward by a factor @xmath7 ).   some of the relationships between parameters, in particular the color  magnitude relations, show stronger correlations for exponential galaxies and concentrated galaxies taken separately than for all galaxies taken together.   we provide a simple set of fits of the dependence of galaxy properties on luminosity for these two sets of galaxies.
we use previously - published moderate - resolution spectra in combination with stellar atmosphere models to derive the first measured chemical abundance ratios in the leo ii dsph galaxy.   we find that for spectra with snr @xmath0, we are able to measure abundances from weak ti, fe and mg lines located near the calcium infrared triplet ( cat ). we also quantify and discuss discrepancies between the metallicities measured from fei lines and those estimated from the cat features.   we find that while the most metal - poor (  @xmath1 ) leo ii stars have ca and ti abundance ratios similar to those of galactic globular clusters, the more metal - rich stars show a gradual decline of ti, mg and ca abundance ratio with increasing metallicity.   finding these trends in this distant and apparently dynamically stable dsph galaxy supports the hypothesis that the slow chemical enrichment histories of the dsph galaxies is universal, independent of any interaction with the milky way. combining our spectroscopic abundances with published broadband photometry and updated isochrones  , we are able to approximate stellar ages for our bright rgb stars to a relative precision of 2 - 3 gyr. while the derived age - metallicity relationship of leo ii hints at some amount of slow enrichment, the data are still statistically consistent with no enrichment over the history of leo ii.
the ability to extract public opinion from web portals such as review sites, social networks and blogs will enable companies and individuals to form a view, an attitude and make decisions without having to do lengthy and costly researches and surveys. in this paper machine   learning techniques are used for determining the polarity of forum posts on kajgana which are written in macedonian language.   the posts are classified as being positive, negative or neutral.   we test different feature metrics and classifiers and provide detailed evaluation of their participation in improving the overall performance on a manually generated dataset. by achieving 92% accuracy,   we show that the performance of systems for automated opinion mining is comparable to a human evaluator, thus making it a viable option for text data analysis. finally, we present a few statistics derived from the forum posts using the developed system.    opinion mining, classification, natural language processing, macedonian language
in this paper, we investigate detectability and identifiability of attacks on linear dynamical systems that are subjected to external disturbances.   we generalize a concept for a security index, which was previously introduced for static systems.   the generalized index exactly quantifies the resources necessary for targeted attacks to be undetectable and unidentifiable in the presence of disturbances.   this information is useful for both risk assessment and for the design of anomaly detectors.   finally, we show how techniques from the fault detection literature can be used to decouple disturbances and to identify attacks, under certain sparsity constraints.
gravitational wave astronomy has become a reality after the historical detections accomplished during the first observing run of the two advanced ligo detectors. in the following years  , the number of detections is expected to increase significantly with the full commissioning of the advanced ligo, advanced virgo and kagra detectors.   the development of sophisticated data analysis techniques to improve the opportunities of detection for low signal - to - noise - ratio events is hence a most crucial effort.   we present in this paper one such technique, dictionary - learning algorithms, which have been extensively developed in the last few years and successfully applied mostly in the context of image processing.   however, to the best of our knowledge, such algorithms have not yet been employed to denoise gravitational wave signals. by building dictionaries from numerical relativity templates of both, binary black holes mergers and bursts of rotational core collapse,   we show how machine - learning algorithms based on dictionaries can be also successfully applied for gravitational wave denoising.   we use a subset of signals from both catalogs, embedded in non - white gaussian noise, to assess our techniques with a large sample of tests and to find the best model parameters.   the application of our method to the actual signal gw150914 shows promising results.   dictionary - learning algorithms could be a complementary addition to the gravitational wave data analysis toolkit.   they may be used to extract signals from noise and to infer physical parameters if the data are in good enough agreement with the morphology of the dictionary atoms.
gas - grain and gas - phase reactions dominate the formation of molecules in the interstellar medium ( ism ).   gas - grain reactions require a substrate ( e.g. a dust or ice grain ) on which the reaction is able to occur.   the formation of molecular hydrogen ( h@xmath0 ) in the ism is the prototypical example of a gas - grain reaction. in these reactions,   an atom of hydrogen will strike a surface, stick to it, and diffuse across it.   when it encounters another adsorbed hydrogen atom, the two can react to form molecular hydrogen and then be ejected from the surface by the energy released in the reaction.   we perform in - depth classical molecular dynamics ( md ) simulations of hydrogen atoms interacting with an amorphous water - ice surface.   this study focuses on the first step in the formation process ; the sticking of the hydrogen atom to the substrate.   we find that careful attention must be paid in dealing with the ambiguities in defining a sticking event  . the technical definition of a sticking event will affect the computed sticking probabilities and coefficients. here, using our new definition of a sticking event, we report sticking probabilities and sticking coefficients for nine different incident kinetic energies of hydrogen atoms  across seven different temperatures of dust grains .   we find that probabilities and coefficients vary both as a function of grain temperature and incident kinetic energy over the range of 0.99 - 0.22.
isospin - violating dark matter ( ivdm ) provides a possible mechanism to ameliorate the tension among recent direct detection experiments. for ivdm  , we demonstrate that the results of direct detection experiments based on neutron - rich target nuclei may depend strongly on the density dependence of the symmetry energy which is presently largely unknown and controls the neutron skin thickness that reflects the relative difference of neutron and proton form factors in the neutron - rich nuclei. in particular  , using the neutron and proton form factors obtained from skyrme - hartree - fock calculations by varying the symmetry energy within the uncertainty region set by the latest model - independent measurement of the neutron skin thickness of @xmath0pb from prex experiment at jlab, we find that, for ivdm with neutron - to - proton coupling ratio fixed to @xmath1, the form factor effect may enhance the sensitivity of xe - based detectors ( e.g., xenon100 and lux ) to the dm - proton cross section by a factor of @xmath2 in the dm mass region constrained by cmds - ii(si ) and even by more than an order of magnitude for heavy dm with mass larger than @xmath3 gev, compared with the results using the empirical helm form factor.   our results further indicate that the form factor effect can significantly modify the recoil spectrum of xe - based detectors for heavy ivdm with @xmath1.
the structural and elastic properties of diamond nanocomposites and ultrananocrystalline diamond films ( uncd ) are investigated using both empirical potentials and tight binding schemes.   we find that both materials are extremely hard, but their superb diamondlike properties are limited by their @xmath0 component. in diamond composites, the @xmath0 atoms are found in the matrix and far from the interface with the inclusion, and they are responsible for the softening of the material. in uncd,   the @xmath0 atoms are located in the grain boundaries.   they offer relaxation mechanisms which relieve the strain but, on the other hand, impose deformations that lead to softening. the higher the @xmath0 component the less rigid these materials are.   ,   , and    carbon, ultrananocrystalline diamond, amorphous materials, nanocomposite, grain boundaries, elastic properties
we present a large bank of chemical profiles and pulsation periods suited for asteroseismological studies of zz ceti ( or dav ) variable stars.   our background equilibrium da white dwarf models are the result of fully evolutionary computations that take into account the complete history of the progenitor stars from the zams.   the models are characterized by self - consistent chemical structures from the centre to the surface, and cover a wide range of stellar masses, effective temperatures, and h envelope thicknesses.   we present dipole and quadrupole pulsation @xmath0-mode periods comfortably covering the interval of periods observed in zz ceti stars.   complete tabulations of chemical profiles and pulsation periods to be used in asteroseismological period fits, as well as other quantities of interest, can be freely downloaded from our website ( http://www.fcaglp.unlp.edu.ar/evolgroup ).   -4 mm
we compute the average luminosity of x - ray flares as a function of time, for a sample of 10 long - duration gamma - ray burst afterglows.   the mean luminosity, averaged over a timescale longer than the duration of the individual flares, declines as a power - law in time with index @xmath0.   we elaborate on the properties of the central engine that can produce such a decline. assuming that the engine is an accreting compact object, and for a standard conversion factor between accretion rate and jet luminosity, the switch between a neutrino - cooled thin disk and a non - cooled thick disk takes place at the transition from the prompt to the flaring phase.   we discuss the implications of this coincidence under different scenarios for the powering of the grb outflow.   we also show that the interaction of the outflow with the envelope of the progenitor star can not produce flares out of a continuous relativistic flow, and conclude that it is the dynamics of the disk or the jet - launching mechanism that generates an intrinsically unsteady outflow on timescales much longer than the dynamical timescale of the system.   this is consistent with the fact that x - ray flares are observed in short - duration grbs as well as in long - duration ones.   gamma - ray : bursts
the macho project has been monitoring about ten million stars in the large magellanic cloud in the search for gravitational microlensing events caused by massive compact halo objects ( machos ) in the halo of the milky way. in our standard analysis, we have searched this data set for well sampled, long duration microlensing lightcurves, detected several microlensing events consistent with machos in the @xmath0 mass range, and set limits on the abundance of objects with masses @xmath1. in this paper, we present a different type of analysis involving the search for very short time scale brightenings of stars which is used to set strong limits on the abundance of lower mass machos.   our analysis of the first two years of data toward the lmc indicates that machos with masses in the range @xmath2 can not make up the entire mass of a standard spherical dark halo. combining these results with those from the standard analysis  , we find that the halo dark matter may not be comprised of objects with masses @xmath3.   # 110^#1    * ( the macho collaboration ) *
the optical and near - ir emission from some classes of supernovae ( sne ), including type iin and possibly some super - luminous sne, is likely powered by a collision between the sn ejecta and dense circumstellar material ( csm ).   we argue that for a range of csm masses and their radii, a collisionless shock can form, allowing for efficient cosmic - ray ( cr ) acceleration.   we show that @xmath0 collisions between these newly accelerated crs and the csm leads to not only gamma rays but also secondary electrons and positrons that radiate synchrotron photons in the high - frequency radio bands.   our estimates imply that various facilities including the jansky very large array ( vla ) and the atacama large millimeter / submillimeter array ( alma ) may observe such sne at gpc distances by followup observations in months - to - years, although the detectability strongly depends on the csm density as well as observed frequency.   detecting this signal would give us a unique probe of cr acceleration at early times, and even non - detections can put interesting limits on the possibility of cr ion acceleration.   following our previous work, we also show that gev gamma rays can escape from the system without severe attenuation, encouraging point - source and stacking analyses with _ fermi_. we provide recipes for diagnosing interaction - powered sn scenario with multi - messenger ( neutrino and gamma - ray ) observations.       non - thermal  supernovae
supermassive black holes appear to be generic components of galactic nuclei. following their formation in the early universe, black holes   should often find themselves in bound pairs as a consequence of galaxy mergers. the greatest uncertainty in estimating the coalescence time of black hole binaries is the degree to which a binary wanders about the center of the galactic potential.   a simple model for binary decay is presented which qualitatively reproduces the evolution observed in the @xmath0-body simulations.   the model predicts binary coalescence times that are never less than several billion years.   mass ejection by a decaying black hole binary should substantially lower the density of its host nucleus.   the weak density cusps of bright ellipticals may be explained in this way if it is assumed that these galaxies formed from nearly gas - free mergers.   # 1#23.6pt
in neutrino oscillation experiments, neutrino interactions at the detector are simulated using event generators which attempt to reflect our understanding of nuclear physics.   we study the impact of different neutrino interactions and nuclear models on the determination of neutrino oscillation parameters.   we use two independent neutrino event generators, genie and gibuu, and apply them to a setup with a conventional neutrino beam aiming at a water erenkov detector, for which only the qe - like sample is selected.   subsequently, we perform a fit to the oscillation parameters in the @xmath0 disappearance channel.
a relativistic version of pauli paramagnetism for @xmath0 system inside a strongly magnetized neutron star has been developed.   an analytical expressions for the saturation value of magnetic field strength for each of these constituents at which they are completely polarized have been obtained. from the fully polarized configuration of electronic component, an upper limit for neutron star magnetic field is predicted.   it has been concluded that indeed, magnetars, as stronly magnetized young neutron stars can not exist if the constituents are electron, proton and neutron in @xmath1-equilibrium.   an alternative model has been proposed.   1.5 cm
* *    ultrafast synchrotron microtomography has been used to study _ in - situ _ and in real time the initial stages of silicate glass melt formation from crystalline granular raw materials.   significant and unexpected rearrangements of grains occur below the nominal eutectic temperature, and several drastically different solid - state reactions are observed to take place at different types of intergranular contacts.   these reactions have a profound influence on the formation and the composition of the liquids produced, and control the formation of defects.   , @xmath0, and @xmath1c.   fragmented sodium carbonate grains react with sand to produce porous crystalline silicates ( panel b ), and rare liquid bridges ( white arrow in panel b ).   further increase in temperature leads to formation of a significant proportion of liquid ( panel c ), finally reaching a state in which the the granular packing is transformed into a viscous melt with bubbles and grain inclusions ( d ).    ]
the 2@xmath03 channel pseudo vertex position detector ( pvpd ) in the star experiment at rhic has been upgraded to a 2@xmath019 channel detector in the same acceptance, called the vertex position detector ( vpd ).   this detector is fully integrated into the star trigger system and provides the primary input to the minimum - bias trigger in au@xmath1au collisions.   the information from the detector is used both in the star level-0 trigger and offline to measure the location of the primary collision vertex along the beam pipe and the event  start time " needed by other fast - timing detectors in star.   the offline timing resolution of single detector channels in full - energy au@xmath1au collisions is @xmath2100 ps, resulting in a start time resolution of a few tens of picoseconds and a resolution on the primary vertex location of @xmath21 cm.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    vertex position detector, time resolution 25.75.cj, 29.40.cs    @xmath3 corresponding author.   _ e - mail address : _ llope@rice.edu.
we address theoretically the optical parametric oscillator based on semiconductor cavity exciton - polaritons under a pulsed excitation.   a `` hyperspin '' formalism is developed which allows, in the case of large number of polaritons, to reduce quantum dynamics of the parametric oscillator wavefunction to the liouville equation for the classical probability distribution.   implications for the statistics of polariton ensembles are analyzed.
we consider how well the dark energy equation of state @xmath0 as a function of red shift @xmath1 will be measured using current and anticipated experiments.   we use a procedure which takes fair account of the uncertainties in the functional dependence of @xmath0 on @xmath1, as well as the parameter degeneracies, and avoids the use of strong prior constraints.   we apply the procedure to current data from wmap, sdss, and the supernova searches, and obtain results that are consistent with other analyses using different combinations of data sets.   the effects of systematic experimental errors and variations in the analysis technique are discussed.   next, we use the same procedure to forecast the dark energy constraints achieveable by the end of the decade, assuming 8 years of wmap data and realistic projections for ground - based measurements of supernovae and weak lensing.   we find the @xmath2 constraints on the current value of @xmath0 to be @xmath3, and on @xmath4 ( between @xmath5 and @xmath6 ) to be @xmath7.   finally, we compare these limits to other projections in the literature. most show only a modest improvement ; others show a more substantial improvement, but there are serious concerns about systematics.   the remaining uncertainty still allows a significant span of competing dark energy models.   most likely, new kinds of measurements, or experiments more sophisticated than those currently planned, are needed to reveal the true nature of dark energy.
we generalize the notion of quasi - local charges, introduced by p. tod for yang   mills fields with unitary gauge groups, to non - abelian gauge theories with _ arbitrary _ gauge group, and calculate its small sphere and large sphere limits both at spatial and null infinity. we show that for semisimple gauge groups _ no _ reasonable definition yield conserved _ total _ charges and newman  penrose ( np ) type quantities at null infinity in generic, radiative configurations.   the conditions of their conservation, both in terms of the field configurations and the structure of the gauge group, are clarified.   we also calculate the np quantities for stationary, asymptotic solutions of the field equations with vanishing magnetic charges, and illustrate these by explicit solutions with various gauge groups.
in baseball games, the coefficient of restitution of baseballs strongly affects the flying distance of batted balls, which determines the home - run probability. in japan  , the range of the coefficient of restitution of official baseballs has changed frequently over the past five years, causing the number of home runs to vary drastically.   we analyzed data from japanese baseball games played in 2014 to investigate the statistical properties of pitched balls.   in addition, we used the analysis results to develop a baseball - batting simulator for determining the home - run probability as a function of the coefficient of restitution.   our simulation results are explained by a simple theoretical argument.
we have investigated spin reorientation phenomena and interaction driven effects under the presence of applied strains on the ( 001 ) surface of pb@xmath0sn@xmath1(te, se ) topological crystalline insulators, which host multiple dirac cones.   our analysis is based on a four - band @xmath2 model, which captures the spin and orbital textures of the surface states at low energies around the @xmath3 and @xmath4 points, including the lifshitz transition. even without breaking the time - reversal symmetry  , we find that certain strains which break the mirror symmetry can induce hedgehog - like spin texture associated with gap formation at the dirac points.   the chern number of the gapped surface ground state is shown to be tunable through the interplay of strains and a perpendicular zeeman field.   we also consider effects of strain in the presence of interactions in driving competing orders, and obtain the associated phase diagram at the mean - field level.   potential applications of our results for low power consuming electronics are discussed.
we discuss the various manifestations of quantum decoherence in the forms of dephasing, entanglement with the environment, and revelation of `` which - path '' information. as a specific example, we consider an electron interference experiment.   the coupling of the coherent electrons to the quantized electromagnetic field illustrates all of these versions of decoherence.   this decoherence has two equivalent interpretations, in terms of photon emission or in terms of aharonov - bohm phase fluctuations.   we consider the case when the coherent electrons are coupled to photons in a squeezed vacuum state. the time - averaged result is increased decoherence.   however, if only electrons which are emitted during selected periods are counted, the decoherence can be suppressed below the level for the photon vacuum.   this is the phenomenon of _ recoherence_.   this effect is closely related to the quantum violations of the weak energy condition, and is restricted by similar inequalities.   we give some estimates of the magnitude of the recoherence effect and discuss prospects for observing it in an electron interferometry experiment.
we investigate the electronic structure of the inas / inp quantum dots using an atomistic pseudopotential method and compare them to those of the inas / gaas qds.   we show that even though the inas / inp and inas / gaas dots have the same dot material, their electronic structure differ significantly in certain aspects, especially for holes : ( i ) the hole levels have a much larger energy spacing in the inas / inp dots than in the inas / gaas dots of corresponding size.   ( ii ) furthermore, in contrast with the inas / gaas dots, where the sizeable hole @xmath0, @xmath1 intra - shell level splitting smashes the energy level shell structure, the inas / inp qds have a well defined energy level shell structure with small @xmath0, @xmath1 level splitting, for holes. (   iii ) the fundamental exciton energies of the inas / inp dots are calculated to be around 0.8 ev ( @xmath2 1.55 @xmath3 m ), about 200 mev lower than those of typical inas / gaas qds, mainly due to the smaller lattice mismatch in the inas / inp dots.   ( iii ) the widths of the exciton @xmath4 shell and @xmath5 shell are much narrower in the inas / inp dots than in the inas / gaas dots.   ( iv ) the inas / gaas and inas / inp dots have a reversed light polarization anisotropy along the  and  directions.
i begin by reviewing some recent work on the status of the geodesic principle in general relativity and the geometrized formulation of newtonian gravitation.   i then turn to the question of whether either of these theories might be said to `` explain '' inertial motion.   i argue that there is a sense in which _ both _ theories may be understood to explain inertial motion, but that the sense of `` explain '' is rather different from what one might have expected.   this sense of explanation is connected with a view of theories   i call it the `` puzzleball view''on which the foundations of a physical theory are best understood as a network of mutually interdependent principles and assumptions.    general relativity, newtonian gravitation, explanation, inertial motion
it is shown explicitly how self - similar graphs can be obtained as ` blow - up'constructions of finite cell graphs @xmath0.   this yields a larger family of graphs than the graphs obtained by discretising continuous self - similar fractals.    for a class of symmetrically self - similar graphs we study   the simple random walk on a cell graph @xmath0, starting in a vertex @xmath1 of the boundary of @xmath0.   it is proved that the expected number of returns to @xmath1 before hitting another vertex in the boundary coincides with the resistance scaling factor.   using techniques from complex rational iteration and singularity analysis for green functions we compute the asymptotic behaviour of the @xmath2-step transition probabilities of the simple random walk on the whole graph.   the results of grabner and woess for the sierpiski graph are generalised to the class of symmetrically self - similar graphs and at the same time the error term of the asymptotic expression is improved.   finally we present a criterion for the occurrence of oscillating phenomena of the @xmath2-step transition probabilities.   bernhard  krn is supported by the project p14379-mat of the austrian science fund ( fwf)]elmar  teufl is supported by the start - project y96-mat of the fwf ]
we report the discovery of a quasar pair at @xmath0 separated by 21.   both objects were identified as quasar candidates using simple color selection techniques applied to photometric catalogs from the cfht legacy survey ( cfhtls ).   spectra obtained with the mmt present no discernible offset in redshift between the two objects ; on the other hand, there are clear differences in the emission line profiles and in the multiwavelength spectral energy distributions that strongly disfavor the hypothesis that they are gravitationally lensed images of a single quasar.   both quasars are surprisingly bright given their proximity ( a projected separation of @xmath1  kpc ), with @xmath2 and @xmath3.   previous measurements of the luminosity function demonstrate that luminous quasars are extremely rare at @xmath0 ; the existence of this pair suggests that quasars have strong small - scale clustering at high redshift. assuming a real - space correlation function of the form @xmath4  , this discovery implies a correlation length @xmath5@xmath6, consistent with a rapid strengthening of quasar clustering at high redshift as seen in previous observations and predicted by theoretical models where feedback effects are inefficient at shutting down black hole growth at high redshift.
we find the green s functions for the accretion disk with the fixed outer radius and time - independent viscosity. with the green s functions, a viscous evolution of the disk with any initial conditions   can be described.   two types of the inner boundary conditions are considered : the zero stress tensor and the zero accretion rate. the variable mass inflow at the outer radius can also be included.   the well - known exponential decline of the accretion rate is a part of the solution with the inner zero stress tensor.   the solution with the zero central accretion rate is applicable to the disks around stars with the magnetosphere s boundary exceeding the corotation radius. using the solution,   the viscous evolution of disks in some binary systems can be studied.   we apply the solution with zero inner stress tensor to outbursts of short - period x - ray transients during the time around the peak.   it is found that for the kramers regime of opacity and the initial surface density proportional to the radius, the rise time to the peak is @xmath0 and the @xmath1-folding time of the decay is @xmath2.   comparison to non - stationary @xmath3-disks shows that both models with the same value of viscosity at the outer radius produce similar behaviour on the viscous time - scale. for six bursts in x - ray novae, which exhibit fast - rise - exponential - decay and   are fitted by the model, we find a way to restrict the turbulent.
we report findings from the first set of data in a current survey to establish conclusively whether jets from young stars rotate. we observed the bi - polar jets from the t tauri stars th28 and rw aur, and the blue - shifted jet from t tauri star lkh@xmath0321, using the hubble space telescope imaging spectrograph ( hst / stis ).   forbidden emission lines ( fels ) show distinct and systematic velocity asymmetries of 10  25 ( @xmath1 5 ) km  s@xmath2 at a distance of 0@xmath3.3 from the source, representing a ( projected ) distance of @xmath4 40 au along the jet in the case of rw aur, @xmath4 50 au for th28, and 165 au in the case of lkh@xmath0321.   these velocity asymmetries are interpreted as rotation in the initial portion of the jet where it is accelerated and collimated. for the bi - polar jets, both lobes appear to rotate in the same direction.   values obtained were in agreement with the predictions of mhd disk - wind models @xcite.   finally, we determine, from derived toroidal and poloidal velocities, values for the distance from the central axis of the footpoint for the jet s low velocity component of @xmath4 0.5 - 2 au, consistent with the models of magneto - centrifugal launching @xcite.
thermal expansion in materials can be accurately modeled with careful phonon calculations within density functional theory. however, because of interest in controlling thermal expansion and the time consumed evaluating thermal expansion properties of candidate materials, either theoretically or experimentally, an approach to rapidly identifying materials with desirable thermal expansion properties would be of great utility.   we show that the fraction of crystal volume occupied by ions, based upon ionic radii, the deviation of bond coordination divided by mean bond coordination, and the ratio of least to greatest atomic mass are descriptors that correlate with the coefficient of thermal expansion for a variety of materials found in widely accessible databases.   correlation is greatly improved by combining these descriptors in a multi - dimensional quadratic fit.   open space combined with a range of atomic masses and a variety of local bond coordinations indicates materials with lower coefficients of thermal expansion.   materials with single - valued local coordination and less open space have the highest coefficients of thermal expansion.
in earlier work, the abstract state machine thesis  that arbitrary algorithms are behaviorally equivalent to abstract state machines  was established for several classes of algorithms, including ordinary, interactive, small - step algorithms.   this was accomplished on the basis of axiomatizations of these classes of algorithms. here   we extend the axiomatization and, in a companion paper, the proof, to cover interactive small - step algorithms that are not necessarily ordinary.   this means that the algorithms ( 1 )  can complete a step without necessarily waiting for replies to all queries from that step and ( 2 )  can use not only the environment s replies but also the order in which the replies were received.
we study experimentally the intermittent progress of the mechanically - induced martensitic transformation in a cu - al - be single crystal through a full - field measurement technique : the grid method.   we utilize an in - house especially designed gravity - based device, wherein a system controlled by water pumps applies a perfectly monotonic uniaxial load through very small force increments.   the sample exhibits hysteretic superelastic behavior during the forward and reverse cubic - monoclinic transformation, produced by the evolution of the strain field of the phase microstructures.   the in - plane linear strain components are measured on the sample surface during the loading cycle, and we characterize for the first time the strain intermittency in a number of ways, showing the emergence of power - law behavior for the strain avalanching over almost six decades of magnitude.   we also describe the non - stationarity and the asymmetry observed in the forward vs.  the reverse transformation.   the present experimental approach, which allows for the monitoring of the reversible martensitic transformation both locally and globally in the crystal, proves useful and enhances our capabilities in the analysis and possible control of transition - related phenomena in shape - memory alloys.
we present a user - friendly, but powerful interface for the data mining of scientific repositories.   we present the tool in use with actual astronomy data and show how it may be used to achieve many different types of powerful semantic queries.   the tool itself hides the gory details of query formulation, and data retrieval from the user, and allows the user to create workflows which may be used to transform the data into a convenient form.
a recently proposed purification method, in which the zeno - like measurements of a subsystem can bring about a distillation of another subsystem in interaction with the former, is utilized to yield entangled states between distant systems.   it is shown that the measurements of a two - level system locally interacting with other two spatially separated not coupled subsystems, can distill entangled states from the latter irrespectively of the initial states of the two subsystems.
the variation of the kinematical properties of the galactic thick disk with galactic height @xmath0 are studied by means of 412 red giants observed in the direction of the south galactic pole up to 4.5  kpc from the plane.   we confirm the non - null mean radial motion toward the galactic anticenter found by other authors, but we find that it changes sign at @xmath1=3  kpc, and the proposed inward motion of the lsr alone can not explain these observations.   the rotational velocity decreases with @xmath1 by @xmath2  km  s@xmath3  kpc@xmath3, but the data are better represented by a power - law with index 1.25, similar to that proposed from the analysis of sdss data.   all the velocity dispersions increase with @xmath1, but the vertical gradients are small.   the dispersions grow proportionally, with no significant variation of the anisotropy.   the ratio @xmath4/@xmath5=2 suggests that the thick disk could have formed from a low - latitude merging event.   the vertex deviation increases with galactic height, reaching @xmath620 degrees at @xmath1=3.5  kpc.   the tilt angle also increases, and the orientation of the ellipsoid in the radial - vertical plane is constantly intermediate between the alignment with the cylindrical and the spherical coordinate systems. the tilt angle at @xmath1=2  kpc coincides with the expectations of mond, but an extension of the calculations to higher @xmath1 is required to perform a conclusive test.   finally, between 2.5 and 3.5  kpc we detect deviations from the linear trend of many kinematical quantities, suggesting that some kinematical substructure could be present.
we develop a description of diffusion limited growth in solid - solid transformations, which are strongly influenced by elastic effects.   density differences and structural transformations provoke stresses at interfaces, which affect the phase equilibrium conditions.   we formulate equations for the interface kinetics similar to dendritic growth and study the growth of a stable phase from a metastable solid in both a channel geometry and in free space.   we perform sharp interface calculations based on green s function methods and phase field simulations, supplemented by analytical investigations. for pure dilatational transformations   we find a single growing finger with symmetry breaking at higher driving forces, whereas for shear transformations the emergence of twin structures can be favorable.   we predict the steady state shapes and propagation velocities, which can be higher than in conventional dendritic growth.
globular star clusters are among the first stellar populations to have formed in the milky way, and thus only a small sliver of their initial spectrum of stellar types are still burning hydrogen on the main - sequence today.   almost all of the stars born with more mass than 0.8  @xmath0 have evolved to form the white dwarf cooling sequence of these systems, and the distribution and properties of these remnants uniquely holds clues related to the nature of the now evolved progenitor stars. with ultra - deep hst imaging observations, rich white dwarf populations of four nearby milky way globular clusters have recently been uncovered, and are found to extend an impressive 5  8 magnitudes in the faint - blue region of the h - r diagram. in this paper, we characterize the properties of these population ii remnants by presenting the first direct mass measurements of individual white dwarfs near the tip of the cooling sequence in the nearest of the milky way globulars, m4. based on gemini / gmos and keck / lris multiobject spectroscopic observations,   our results indicate that 0.8  @xmath0 population ii main - sequence stars evolving today form 0.53 @xmath1 0.01  @xmath0 white dwarfs.   we discuss the implications of this result as it relates to our understanding of stellar structure and evolution of population ii stars and for the age of the galactic halo, as measured with white dwarf cooling theory.
analysis of the properties of resonant modes in a reentrant cavity structure comprising of a post and a ring was undertaken and verified experimentally.   in particular we show the existence of higher order reentrant cavity modes in such a structure.   results show that the new cavity has two re - entrant modes, one which has a better displacement sensitivity than the single post resonator and the other with a reduced sensitivity.   the more sensitive mode is better than the single post resonator by a factor of 2 to 1.5 when the gap spacing is below 100 @xmath0 m.   this type of cavity has the potential to operate as a highly sensitive transducer for a variety of precision measurement applications, in particular applications which require coupling to more than one sensitive transducer mode.   finite element method, q - factor, reentrant cavity, transducer.
recently li and xia have proposed a transmission scheme for wireless relay networks based on the alamouti space time code and orthogonal frequency division multiplexing to combat the effect of timing errors at the relay nodes.   this transmission scheme is amazingly simple and achieves a diversity order of two for any number of relays.   motivated by its simplicity, this scheme is extended to a more general transmission scheme that can achieve full cooperative diversity for any number of relays.   the conditions on the distributed space time block code ( dstbc ) structure that admit its application in the proposed transmission scheme are identified and it is pointed out that the recently proposed full diversity four group decodable dstbcs from precoded co - ordinate interleaved orthogonal designs and extended clifford algebras satisfy these conditions.   it is then shown how differential encoding at the source can be combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full cooperative diversity in asynchronous wireless relay networks with no channel information and also no timing error knowledge at the destination node.   finally, four group decodable distributed differential space time block codes applicable in this new transmission scheme for power of two number of relays are also provided.
we show that a triple - product correlation in the neutron radiative @xmath0-decay rate, characterized by the kinematical variable @xmath1, where @xmath2, isolates the pseudo - chern - simons term found by harvey, hill, and hill as a consequence of the baryon vector current anomaly and su(2)@xmath3@xmath4u(1)@xmath5 gauge invariance at low energies.   the correlation appears if the imaginary part of the coupling constant is nonzero, so that its observation at anticipated levels of sensitivity would reflect the presence of sources of cp violation beyond the standard model.   we compute the size of the asymmetry in @xmath6 decay as a function of the coupling, estimate the effect of standard - model final - state interactions, and discuss the role nuclear processes can play in discovering the effect.   @xmath0-decay, decay correlations, cp violation    23.40.-s, 11.30.er, 12.39.fe, 12.15.-y
stecker, malkan and scully, have shown how ongoing deep surveys of galaxy luminosity functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities for energies from 0.03 ev to the lyman limit at 13.6 ev and for redshifts out to 6 ( called here the intergalactic background light or ibl ). from these calculations of the ibl at various redshifts  , they predict the present and past optical depth of the universe to high energy @xmath0-rays owing to interactions with photons of the ibl and the 2.7 k cmb.   we discuss here how this proceedure can be reversed by looking for sharp cutoffs in the spectra of extragalactic @xmath0-ray sources such as blazars at high redshifts in the multi - gev energy range with _   glast _   ( gamma - ray large are space telescope ). by determining the cutoff energies of sources with known redshifts  , we can refine our determination of the ibl photon densities in the past, _   i.e. _, the _ archeo - ibl _, and therefore get a better measure of the past history of the _ total _ star formation rate.   conversely, observations of sharp high energy cutoffs in the @xmath0-ray spectra of sources at unknown redshifts can be used instead of spectral lines to give a measure of their redshifts.   address = nasa goddard space flight center, greenbelt, md 20771, usa
we present methods for efficient characterization of an optical coherent state @xmath0.   we choose measurement settings adaptively and stochastically, based on data while it is collected.   our algorithm divides the estimation into two distinct steps : ( i ) before the first detection of a vacuum state, the probability of choosing a measurement setting is proportional to detecting vacuum with the setting, which makes using too similar measurement settings twice unlikely ; and ( ii ) after the first detection of vacuum, we focus measurements in the region where vacuum is most likely to be detected. in step ( i )  the detection of vacuum ( a photon ) has a significantly larger effect on the shape of the posterior probability distribution of @xmath1. compared to nonadaptive schemes, our method makes the number of measurement shots required to achieve a certain level of accuracy smaller approximately by a factor proportional to the area describing the initial uncertainty of @xmath1 in phase space. while this algorithm is not directly robust against readout errors, we make it such by introducing repeated measurements in step ( i ).
in this work we analyse the role of low- and intermediate - mass stars in contributing to the chemical enrichment of the interstellar medium.   first we present new sets of stellar yields basing on the results of updated evolutionary calculations, which extend from the zams up to the end of the agb phase ( girardi et al.   2000 ; marigo et al.   1999a ). these new yields, that present a significant dependence on metallicity,   are then compared to those of other available sets ( renzini & voli 1981 ; van de hoek & groenewegen 1997 ).   the resulting differences are explained in terms of different model assumptions   i.e. treatment of convective boundaries, mass loss, dredge - up, hot - bottom burning  and further discussed on the basis of important empirical constraints which should be reproduced by theory   i.e. the initial - final mass relation, white dwarf mass distribution, carbon star luminosity function, and chemical abundances of planetary nebulae.   we show that present models are able to reproduce such constraints in a satisfactory way.
in this paper, we investigate the dynamical formation and evolution of @xmath0-dimensional charged black holes.   we numerically study dynamical collapses of charged matter fields in an anti de sitter background and note the formation of black holes using the double - null formalism.   moreover, we include re - normalized energy - momentum tensors assuming the @xmath1-wave approximation to determine thermodynamical back - reactions to the internal structures.   if there is no semi - classical effects, the amount of charge determines the causal structures.   if the charge is sufficiently small, the causal structure has a space - like singularity.   however, as the charge increases, an inner cauchy horizon appears.   if we have sufficient charge, we see a space - like outer horizon and a time - like inner horizon, and if we give excessive charge, black hole horizons disappear.   we have some circumstantial evidences that weak cosmic censorship is still satisfied, even for such excessive charge cases. also, we confirm that there is mass inflation along the inner horizon, although the properties are quite different from those of four - dimensional cases.   semi - classical back - reactions will not affect the outer horizon, but they will affect the inner horizon. near the center, there is a place where negative energy is concentrated. thus, charged black holes in three dimensions have two types of curvature singularities in general : via mass inflation and via a concentration of negative energy.   finally, we classify possible causal structures.
we present a geometrodynamical method for determining distances to orbital streams of hi gas in the galaxy.   the method makes use of our offset from the galactic centre and assumes that the gas comprising the stream nearly follows a planar orbit about the galactic centre.   we apply this technique to the magellanic stream and determine the distances to all points along it ; a consistency check shows that the angular momentum is approximately constant.   applying this technique to the large magellanic cloud itself gives an independent distance which agrees within its accuracy of around 10%.   relaxing the demand for exact conservation of energy and angular momentum at all points along the stream allows for an increase in orbital period between the lagging end and the front end led by the magellanic clouds.   similar methods are applicable to other long streams of high - velocity clouds, provided they also nearly follow planar orbits ; these would allow otherwise unknown distances to be determined.   galaxies : magellanic clouds  ism : clouds, kinematics and dynamics  methods : analytical
in this paper we extend the gaussian self  consistent method to permit study of the equilibrium and kinetics of conformational transitions for heteropolymers with any given primary sequence.   the kinetic equations earlier derived by us are transformed to a form containing only the mean squared distances between pairs of monomers.   these equations are further expressed in terms of instantaneous gradients of the variational free energy.   the method allowed us to study exhaustively the stability and conformational structure of some periodic and random aperiodic sequences.   a typical phase diagram of a fairly long amphiphilic heteropolymer chain is found to contain phases of the extended coil, the homogeneous globule, the micro   phase separated globule, and a large number of frustrated states, which result in conformational phases of the random coil and the frozen globule.   we have also found that for a certain class of sequences the frustrated phases are suppressed.   the kinetics of folding from the extended coil to the globule proceeds through non  equilibrium states possessing locally compacted, but partially misfolded and frustrated, structure.   this results in a rather complicated multistep kinetic process typical of glassy systems.
bose - einstein correlations ( bec ) observed between identical bosons produced in high energy multiparticle collisions are regarded as very important tool in investigations of multiparticle production processes.   we present here their stochastic feature stressing the fact that they can be regarded as a reflection of correlations of fluctuations present in hadronizing system.   we show in particular that such approach allows for simple modelling of bec in numerical event generators used to describe the multiparticle production processes at high energy collisions.    _ dedicated to stefan pokorski in honour of his 60th birthday _
by making use of the langevin dynamics and its generating functional ( gf ) formulation the influence of the long - range nature of the interaction on the tendency of the glass formation is systematically investigated. in doing so two types of models   is considered : ( i ) the non - disordered model with a pure repulsive type of interaction and ( ii ) the model with a randomly distributed strength of interaction ( a quenched disordered model ).   the long - ranged potential of interaction is scaled with a number of particles @xmath0 in such a way as to enable for gf the saddle - point treatment as well as the systematic @xmath1 - expansion around it.   we show that the non - disordered model has no glass transition which is in line with the mean - field limit of the mode - coupling theory ( mct ) predictions. on the other hand the model with a long - range interaction which above that has a quenched disorder leads to mc - equations which are generic for the @xmath2 - spin glass model and polymeric manifold in a random media.   -15 mm
recent experimental results have confirmed a possible reduction in the gt@xmath0 strengths of pf - shell nuclei.   these proton - rich nuclei are of relevance in the deflagration and explosive burning phases of type ia supernovae.   while prior gt strengths result in nucleosynthesis predictions with a lower - than - expected electron fraction, a reduction in the gt@xmath0 strength can result in an slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by fuller, fowler, and newman based on an independent particle model.   a shell model parametrization has been developed which more closely matches experimental gt strengths.   the resultant electron - capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of type ia supernovae, and the final mass fractions are compared to those obtained using more commonly - used rates.
the x - ray properties of a sample of high redshift ( z@xmath00.6 ), massive clusters observed with @xmath1 and @xmath2 are described, including two exceptional systems.   one, at z=0.89, has an x - ray temperature of t=11.5@xmath3 kev ( the highest temperature of any cluster known at z@xmath00.6 ), an estimated mass of @xmath4(1.4@xmath50.2)x10@xmath6, and appears relaxed.   the other, at z=0.83, has at least three sub - clumps, probably in the process of merging, and may also show signs of faint filamentary structure at large radii, observed in x - rays.   in general there is a mix of x - ray morphologies, from those clusters which appear relaxed and containing little substructure to some highly non - virialized and probably merging systems.   the x - ray gas metallicities and gas mass fractions of the relaxed systems are similar to those of low redshift clusters of the same temperature, suggesting that the gas was in place, and containing its metals, by z@xmath40.8. the evolution of the mass - temperature relation may be consistent with no evolution or with the `` late formation '' assumption.   the effect of point source contamination in the @xmath7 survey from which these clusters were selected is estimated, and the implications for the @xmath7 x - ray luminosity function discussed.       a&a
we investigate evolutionary dynamics of two - strategy matrix games with zealots in finite populations.   zealots are assumed to take either strategy regardless of the fitness.   when the strategy selected by the zealots is the same, the fixation of the strategy selected by the zealots is a trivial outcome.   we study fixation time in this scenario.   we show that the fixation time is divided into three main regimes, in one of which the fixation time is short, and in the other two the fixation time is exponentially long in terms of the population size.   different from the case without zealots, there is a threshold selection intensity below which the fixation is fast for an arbitrary payoff matrix.   we illustrate our results with examples of various social dilemma games.
infrared spectroscopy, interstellar clouds, interstellar molecules    the presence of @xmath0 in the interstellar medium was forecast almost four decades ago.   almost three decades ago it was asserted that its reactions with neutral molecular and atomic species directly lead to the production of many of the interstellar molecules that have been discovered by radio and infrared astronomers. with the recent detection of @xmath0 in interstellar space, astronomers finally have direct confirmation of @xmath0 as the foundation of ion - molecule interstellar chemistry.   although many questions remain to be answered, it is clear that @xmath0 is a unique tool for understanding the properties of interstellar clouds.   
we study the possibility of testing experimentally signatures of p - odd effects related with the vorticity of the medium.   the chiral vortaic effect is generalized to the case of conserved charges different from the electric one. in the case of baryonic charge and chemical potential such effect should manifest itself in neutron asymmetries at the nica accelerator complex measured by the mpd detector.   the required accuracy may be achieved in a few months of accelerator running.   we also discuss polarization of the hyperons and p - odd correlations of particle momenta ( handedness ) as probes of vorticity.   _ we dedicate this paper to the memory of academician _   alexei norairovich sissakian
the gaseous micromegas detector designed for the cern axion search experiment cast, operated smoothly during phase - i, which included the 2003 and 2004 running periods.   it exhibited linear response in the energy range of interest ( 1 - 10kev ), good spatial sensitivity and energy resolution ( 15 - 19% fwhm at 5.9 kev ) as well as remarkable stability.   the detector s upgrade for the 2004 run, supported by the development of advanced offline analysis tools, improved the background rejection capability, leading to an average rate @xmath0 counts / sec / cm2/kev with 94% cut efficiency.   also, the origin of the detected background was studied with a monte - carlo simulation, using the geant4 package.   @xmath1dapnia, centre detudes de saclay, gif sur yvette cedex 91191, france + @xmath2institut fr kernphysik, technische universitt darmstadt, schlossgartenstr. 9, 64289 germany + @xmath3ncsr demokritos, agia paraskevi 15310, athens, greece
the description of the hadron production at very forward rapidities and low transverse momentum is usually made using phenomenological models based on nonperturbative physics.   however, at high energies and large rapidities the wave function of one of the projectiles is probed at very small bjorken @xmath0, being characterized by a large number of gluons. in this kinematical regime, a new state of matter - the color glass condensate ( cgc ) -   is expected to be formed.   one the main characteristics of such system is the presence of a new dynamical momentum scale, the saturation scale @xmath1, which can assume values very larger than the qcd confinement scale @xmath2 and give the scale of the running coupling constant. in this paper   we assume that in particular kinematical region probed by lhc forward ( lhcf ) experiment the saturation scale can be considered the hard momentum scale present in the process and calculate the forward neutral pion production at very low-@xmath3 using a perturbative approach.   we demonstrate that the cgc formalism is able to successfully describe the lhcf data, which can be considered as a compelling indication of the presence of non - linear qcd effects at lhc energies.
we test the isotropy of the local distribution of galaxies using the 2mass extended source catalogue. by decomposing the full sky survey into distinct patches and using a combination of photometric and spectroscopic redshift data, we use both parametric and non - parametric methods to obtain the shape of the luminosity function in each patch.   we use the shape of the luminosity function to test the statistical isotropy of the underlying galaxy distribution.   the parametric estimator shows some evidence of a hemispherical asymmetry in the north / south galactic plane.   however the non - parametric estimator exhibits no significant anisotropy, with the galaxy distribution being consistent with the assumption of isotropy in all regions considered.   the parametric asymmetry is attributed to the relatively poor fit of the functional form to the underlying data.   when using the non - parametric estimator, we do find a dipole in the shape of the luminosity function, with maximal deviation from isotropy at galactic coordinate @xmath0.   however we can ascribe no strong statistical significance to this observation.
the statefinder diagnosic is a useful method for distinguishing different dark energy models. in this paper  , we investigate the new agegraphic dark energy model with interaction between dark energy and matter component by using statefinder parameter pair @xmath0 and study its cosmological evolution.   we plot the trajectories of the new agegraphic dark energy model for different interaction cases in the statefinder plane. as a result  , the influence of the interaction on the evolution of the universe is shown in the statefinder diagrams.
we theoretically study spin and charge transport induced by a twisted light beam irradiated on a disordered surface of a doped three dimensional topological insulator ( ti ).   we find that various types of spin vortices are imprinted on the surface of the ti depending on the spin and orbital angular momentum of the incident light.   the key mechanism for the appearance of the unconventional spin structure is the spin - momentum locking in the surface state of the ti.   besides, the diffusive transport of electrons under an inhomogeneous electric field causes a gradient of the charge density, which then induces nonlocal charge current and spin density as well as the spin current.   we discuss the relation between these quantities within the linear response to the applied electric field using the keldysh - green s function method.   : :    pacs numbers : 78.20.ls
feedback control of quantum systems via continuous measurement involves complex nonlinear dynamics. except in very special cases, even for a single qubit optimal feedback protocols are unknown.   not even do intuitive candidates exist for choosing the measurement basis, which is the primary non - trivial ingredient in the feedback control of a qubit. here   we present a series of arguments that suggest a particular form for the optimal protocol for a broad class of noise sources in the regime of good control.   this regime is defined as that in which the control is strong enough to keep the system close to the desired state. with the assumption of this form   the remaining parameters can be determined via a numerical search.   the result is a non - trivial feedback protocol valid for all feedback strengths in the regime of good control.   we conjecture that this protocol is optimal to leading order in the small parameters that define this regime.   the protocol can be described relatively simply, and as a notable feature contains a discontinuity as a function of the feedback strength.
we propose the possibility of a new phenomenon affecting the settling of dust grains at the terrestrial region in early protoplanetary disks.   sinking dust grains evaporate in a hot inner region during an early stage of disk evolution, and the effects of condensation and evaporation on vertical dust settling can be significant.   a 1-d dust settling model considering both physical and chemical aspects is presented in this paper.   modeling results show that dust grains evaporate as they sink into the hotter interior and form a `` condensation front '' above which dust - composing elements, mg, si, and fe, accumulate, creating a large temperature jump. repeating evaporation at the front inhibits grain growth, resulting in slow settling with a time scale comparable to that of radial evolution.   the time scale of dust settling is predicted to be longer than 10@xmath0 years at 1  au, whereas an order of 10@xmath1 years is suggested by the standard theory of planetary formation.   the new model might also explain some puzzling compositional features observed in chondrites.   our results show different settling behaviors between highly refractory elements, such as al and ca, and moderately refractory elements, such as mg, si, and fe, pointing to the importance of building a more complete model that takes into account both the physical and chemical evolution of protoplanetary disks.
we present time - resolved spectroscopy and photometry of the dwarf nova sbss1108 + 574, obtained during the 2012 outburst.   its quiescent spectrum is unusually rich in helium, showing broad, double - peaked emission lines from the accretion disc.   we measure a line flux ratio hei  5875/h@xmath0=0.81@xmath10.04, a much higher ratio than typically observed in cataclysmic variables ( cvs ).   the outburst spectrum shows hydrogen and helium in absorption, with weak emission of h@xmath0 and hei  6678, as well as strong heii emission.    from our photometry  , we find the superhump period to be 56.34@xmath10.18minutes, in agreement with the previously published result.   the spectroscopic period, derived from the radial velocities of the emission lines, is found to be 55.3@xmath10.8minutes, consistent with a previously identified photometric orbital period, and significantly below the normal cv period minimum.   this indicates that the donor in sbss1108 + 574 is highly evolved.   the superhump excess derived from our photometry implies a mass ratio of @xmath2=0.086@xmath10.014.   our spectroscopy reveals a grazing eclipse of the large outbursting disc.   as the disc is significantly larger during outburst, it is unlikely that an eclipse will be detectable in quiescence.   the relatively high accretion rate implied by the detection of outbursts, together with the large mass ratio, suggests that sbss1108 + 574 is still evolving towards its period minimum.       accretion, accretion discs  binaries : close  stars : individual : s
we address the common problem of calculating intervals in the presence of systematic uncertainties.   we aim to investigate several approaches, but here describe just a bayesian technique for setting upper limits.   the particular example we study is that of inferring the rate of a poisson process when there are uncertainties on the acceptance and the background.   limit calculating software associated with this work is available in the form of c  functions.
peptide nucleic acids ( pna ) are non - natural oligonucleotides mimics, wherein the phosphoribose backbone has been replaced by a peptidic moiety ( n-(2-aminoethyl)glycine ).   this peptidic backbone lends itself to substitution and the @xmath0-position has proven to yield oligomers with enhanced hybridization properties. in this study, we use nuclear magnetic resonance ( nmr ) and circular dichroism ( cd ) to explore the properties of the supramolecular duplexes formed by these species.   we show that standard watson - crick base pair as well as non - standard ones are formed in solution.   the duplexes thus formed present marked melting transition temperatures substantially higher than their nucleic acid homologs.   moreover, the presence of a chiral group on the @xmath0-peptidic backbone increases further this transition temperature, leading to very stable duplexes.   pna duplexes with a chiral backbone present a marked chiral secondary structure, observed by cd, and showing a common folding pattern for all studied structures. nevertheless small differences are observed depending on the details of the nucleobase sequence.   @xmath0-pna, nmr spectroscopy, imino proton, circular dichroism, secondary structure
the dynamic shape relaxation of the two - layer - vesicle is calculated. in additional to the undulation relaxation where the two bilayers move in the same direction, the squeezing mode appears when the gap between the two bilayers is small. at large gap, the inner vesicle relaxes much faster, whereas the slow mode is mainly due to the outer layer relaxation.   we have calculated the viscoelasticity of the dilute two - layer - vesicle suspension.   it is found that for small gap, the applied shear drives the undulation mode strongly while the slow squeezing mode is not much excited. in this limit   the complex viscosity is dominated by the fast mode contribution. on the other hand, the slow mode   is strongly driven by shear for larger gap.   we have determined the crossover gap which depends on the interaction between the two bilayers. for a series of samples where the gap is changed systematically  , it is possible to observe the two amplitude switchings.
the process @xmath0 is analysed using the data collected with the l3 detector at lep at a centre - of - mass energy of @xmath1, corresponding to an integrated luminosity of 176.8pb@xmath2. based on a sample of 42 selected @xmath3 candidates containing an isolated hard photon, the @xmath4 cross section, defined within phase - space cuts,   is measured to be : @xmath5 fb, consistent with the standard model expectation.    including the process @xmath6  , limits are derived on anomalous contributions to the standard model quartic vertices @xmath7 and @xmath8 at 95%  cl : @xmath9    submitted to _ phys.   lett.   b _
we study ground - state properties in a hard - core bose - hubbard model on a layered triangular lattice. combining cluster mean - field theory with the density matrix renormalization group method  , we discuss the effect of the interlayer coupling on the supersolid states realized in a single layered model. by examining the distributions for the particle density and superfluid order parameter, the rich phase diagram of the system is obtained.   we find that the supersolid states are widely stabilized at a commensurate filling, in contrast to the case of the single layered model.   the nature of the supersolid states is also addressed.
increasing observational evidence gathered especially in x - rays and @xmath0-rays during the course of the last few years support the notion that supernova remnants ( snrs ) are galactic particle accelerators up to energies close to the `` knee '' in the energy spectrum of cosmic rays.   this review summarises the current status of @xmath0-ray observations of snrs.   shell - type as well as plerionic type snrs are addressed and prospect for observations of these two source classes with the upcoming glast satellite in the energy regime above 100  mev are given.   ,   supernova remnant, pulsar wind nebula, gamma - ray astronomy 98.38.mz, supernova remnants 98.70.rz, @xmath0-ray sources 98.70.sa, cosmic rays ( origin, acceleration, and interactions )
distant regions close to the plane of our galaxy are largely unexplored by optical surveys as they are hidden by dust.   we have used near - infrared data ( that minimizes dust obscuration ) from the eso public survey vista variables of the via lactea ( vvv ) ( minniti et al.   2011 ; saito et al.   2012 ; henceforth s12 ) to search for distant stars at low latitudes.   we have discovered four cepheid variables within an angular extent of one degree centered at galactic longitude of @xmath0 and galactic latitude of @xmath1.   we use the tightly constrained period - luminosity relationship that these pulsating stars obey ( persson et al. 2004 ; matsunaga et al. 2011 ) to derive distances.   we infer an average distance to these cepheid variables of 90 kpc.   the cepheid variables are highly clustered in angle ( within one degree ) and in distance ( the standard deviation of the distances is 12 kpc ).   they are at an average distance of @xmath2 from the plane and their maximum projected separation is @xmath3.   these young ( @xmath4 100 myr old ), pulsating stars ( bono et al.   2005 ) are unexpected at such large distances from the galactic disk, which terminates at @xmath4 15 kpc ( minniti et al.   2011 ).   the highly clustered nature in distance and angle of the cepheid variables suggests that the stars may be associated with a dwarf galaxy, one that was earlier predicted by a dynamical analysis ( chakrabarti & blitz 2009 ).
the galactic x - ray transient xte  j1752@xmath0223 was shown to have properties of black hole binary candidates. as reported in our previous paper, we identified transient and decelerating ejecta in multi - epoch very long baseline interferometry ( vlbi ) observations with the european vlbi network ( evn ) and the nrao very long baseline array ( vlba ). here   we present new evn and vlba data in which a new transient ejection event and later a stationary component are identified.   the latter is interpreted as a reappearance of the radio core / compact jet during the transition from soft to hard x - ray state.   this component appears to be highly variable in brightness although effects of tropospheric instabilities might play a role too.   we also re - analyze the earlier vlbi data and find that the transient ejecta closer to the core position has significantly higher proper motion, further strengthening the case for strongly decelerating ejecta on the scale of several hundred milli - arcsecond, never observed in x - ray binaries before.   although the distance of the source is not well constrained, it is clear that these ejectas are at least mildly relativistic at the early stages.   moreover, we show the large scale environment of the transient from the westerbork synthesis array data recorded in parallel during the evn run.       stars : individual : xte  j1752@xmath0223  stars : variable : others  ism : jets and outflows  radio continuum : stars  x - rays : binaries.
winner - take - all phenomena are observed in various competitive systems.   we find similar phenomena in replicator models with randomly fluctuating growth rates.   the disparity between winners and losers increases indefinitely, even if all elements are statistically equivalent.   a lognormal distribution describes well the nonstationary time evolution.   if a nonlinear load corresponding to progressive taxation is introduced, a stationary distribution is obtained and disparity widening is suppressed.
we investigate one - dimensional ( 1d ) discrete time quantum walks ( qws ) with spatially or temporally random defects as a consequence of interactions with random environments.   we focus on the qws with chiral symmetry in a topological phase, and reveal that chiral symmetry together with bipartite nature of the qws brings about intriguing behaviors such as coexistence of topologically protected edge states at zero energy and anderson transitions in the 1d chiral class at _ non - zero _ energy in their dynamics.   contrary to the previous studies, therefore, the spatially disordered qws can avoid complete localization due to the anderson transition.   it is further confirmed that the edge states are robust for spatial disorder but not for temporal disorder.
we present lightcurve observations and multiband photometry for 107p / wilson - harrington using five small- and medium - sized telescopes.   the lightcurve has shown a periodicity of @xmath0 @xmath1 ( 7.15 @xmath2 ) and @xmath3 @xmath1 ( 2.38 @xmath2 ), which has a commensurability of 3:1. the physical properties of the lightcurve indicate two models : ( 1 ) 107p / wilson - harrington is a tumbling object with a sidereal rotation period of @xmath0 @xmath1 and a precession period of @xmath3 @xmath1.   the shape has a long axis mode ( lam ) of @xmath4:@xmath5:@xmath6 = 1.0:1.0:1.6.   the direction of the total rotational angular momentum is around @xmath7, @xmath8, or @xmath9, @xmath10.   the nutation angle is approximately constant at @xmath11.   ( 2 ) 107p / wilson - harrington is not a tumbler.   the sidereal rotation period is @xmath0 @xmath1.   the shape is nearly spherical but slightly hexagonal with a short axis mode ( sam ) of @xmath4:@xmath5:@xmath6 = 1.5:1.5:1.0.   the pole orientation is around @xmath12, @xmath13.   in addition, the model includes the possibility of binary hosting. for both models,   the sense of rotation is retrograde.   furthermore, multiband photometry indicates that the taxonomy class of 107p / wilson - harrington is c - type.   no clear
the genotype - fitness map plays a fundamental role in shaping the dynamics of evolution.   however, it is difficult to directly measure a fitness landscape in practice, because the number of possible genotypes is astronomical.   one approach is to sample as many genotypes as possible, measure their fitnesses, and fit a statistical model of the landscape that includes additive and pairwise interactive effects between loci.   here we elucidate the pitfalls of using such regressions, by studying artificial but mathematically convenient fitness landscapes.   we identify two sources of bias inherent in these regression procedures that each tends to under - estimate high fitnesses and over - estimate low fitnesses.   we characterize these biases for random sampling of genotypes, as well as for samples drawn from a population under selection in the wright - fisher model of evolutionary dynamics.   we show that common measures of epistasis, such as the number of monotonically increasing paths between ancestral and derived genotypes, the prevalence of sign epistasis, and the number of local fitness maxima, are distorted in the inferred landscape. as a result  , the inferred landscape will provide systematically biased predictions for the dynamics of adaptation.   we identify the same biases in a computational rna - folding landscape, as well as in regulatory sequence binding data, treated with the same fitting procedure.   finally, we present a method that may ameliorate these biases in some cases.
we use @xmath0-body simulations to measure mass functions in flat cosmological models with quintessence characterized by constant @xmath1 with @xmath2, @xmath3 and @xmath4.   the results are compared to the predictions of the formula proposed by jenkins et al. at different redshifts, in terms of fof masses as well as abell masses appropriate for direct comparison to observations.   the formula reproduces quite well the mass functions of simulated haloes in models with quintessence.   we use the cluster mass function data at a number of redshifts from carlberg et al. to constrain @xmath5, @xmath6 and @xmath1.   the best fit is obtained in the limit @xmath7, but none of the values of @xmath1 in the considered range @xmath8 can actually be excluded.   however, the adopted value of @xmath1 affects significantly the constraints in the @xmath9 plane. taking into account the dependence on @xmath1 we find @xmath10 and @xmath11 ( @xmath12 c.l. ).   since less negative @xmath1 push the confidence regions toward higher @xmath5 and lower @xmath6 we conclude that relaxing the assumption of @xmath2 typically made in such comparisons may resolve the discrepancy between recent cluster mass function results ( yielding rather low @xmath5 and high @xmath6 ) and most other estimates.   the fact that high @xmath1 values are preferred may however also point towards some unknown systematics in the data or the model with constant @xmath1 being inadequate.   methods : @xmath0-body simulations  methods : analytical  cosmology : theory  cosmology : dark matter  galaxies : clusters : general  large - scale structure of universe
b1422 + 231 and pg1115 + 080 are gravitational lens systems producing quadruple qso images where there is real promise that time delays can constrain the hubble constant.   in addition, the lensing galaxies are both part of groups which can play an important role in modelling the lens potential.   this article reports redshifts for the lensing galaxies and three neighboring galaxies in each of the two systems.   b1422 + 231 consists of a group at @xmath0 with a dispersion of 733, and pg1115 + 080 is a group at @xmath1 with a dispersion of 326.   one of the neighboring galaxies in the b1422 + 231 system turned out to be an emission line galaxy at @xmath2, suggesting that qso light passing through b1422 + 231 may have been subjected to lensing by a cluster at this more distant redshift.   the velocity dispersion of the lensing galaxy in pg1115 + 080 is determined to be @xmath3  ( 1  square aperture ), which is surprisingly large given the image splittings of 1.2  in that system.   _ subject headings : cosmology  distance scale  gravitational lensing  quasars : individual ( b1422 + 231, pg1115 + 080 ) _   # 1#1    = cmr8
we introduce a new approximate multiresolution analysis ( mra ) using a single gaussian as the scaling function, which we call gaussian mra ( gmra ).   we employ this new tool to accurately and efficiently compute the probability density function ( pdf ) of the product of two independent random variables.   in contrast with monte - carlo ( mc ) type methods ( the only other universal approach known to address this problem ), our method not only achieves accuracies beyond the reach of mc but also produces a pdf expressed as a gaussian mixture, thus allowing for further efficient computations.   we also show that an exact mra corresponding to our gmra can be constructed for a matching user - selected accuracy.
we briefly outline the physics underlying the mechanical and thermal properties of brown dwarfs, which characterizes their interiors and their atmospheres.   we mention the most recent improvements realyzed in the theory of brown dwarfs and the connection with experimental and observational tests of this theory.
we calculate root mean square ( rms ) deviations from equilibrium for atoms in a two dimensional crystal with local ( e.g. covalent ) bonding between close neighbors.   large scale monte carlo calculations are in good agreement with analytical results obtained in the harmonic approximation.   when motion is restricted to the plane, we find a slow ( logarithmic ) increase in fluctuations of the atoms about their equilibrium positions as the crystals are made larger and larger.   we take into account fluctuations perpendicular to the lattice plane, manifest as undulating ripples, by examining dual - layer systems with coupling between the layers to impart local rigidly ( i.e. as in sheets of graphene made stiff by their finite thickness ).   surprisingly, we find a rapid divergence with increasing system size in the vertical mean square deviations, independent of the strength of the interplanar coupling.   we consider an attractive coupling to a flat substrate, finding that even a weak attraction significantly limits the amplitude and average wavelength of the ripples.   we verify our results are generic by examining a variety of distinct geometries, obtaining the same phenomena in each case.
we study the phase mixing and dissipation of a packet of standing shear alfvn waves localized in a region with non - uniform alfvn background velocity.   we investigate the validity of the exponential damping law in time, @xmath0, presented by heyvaerts & priest ( 1983 ) for different ranges of lundquist, @xmath1, and reynolds, @xmath2, numbers.   our numerical results shows that it is valid for @xmath3.   = 16truecm = 23truecm = -1.3truecm = -2truecm = 1.20 cm = 1.60 cm    * key words : *  sun : corona  sun : magnetic fields  sun : oscillations
first results on charm quarkonia production in heavy ion collisions at the relativistic heavy ion collider ( rhic ) are presented.   the yield of @xmath0 s measured in the phenix experiment via electron - positron decay pairs at mid - rapidity for au - au reactions at @xmath1 = 200 gev are analyzed as a function of collision centrality.   for this analysis we have studied 49.3 million minimum bias au - au reactions.   we present the @xmath0 invariant yield @xmath2 for peripheral and mid - central reactions. for the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits.   we compare these results with our @xmath0 measurement from proton - proton reactions at the same energy.   we find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
we report characterization and magnetic studies of mixtures of micrometer - size ribbons of mn@xmath0 acetate and micrometer - size particles of ybacuo superconductor.   extremely narrow zero - field spin - tunneling resonance has been observed in the mixtures, pointing to the absence of the inhomogeneous dipolar broadening.   it is attributed to the screening of the internal magnetic fields in the magnetic particles by josephson currents between superconducting grains surrounding the particles.
we investigate the adaptation of the time headways in car - following models as a function of the local velocity variance, which is a measure of the inhomogeneity of traffic flow.   we apply this mechanism to several car - following models and simulate traffic breakdowns in open systems with an on - ramp as bottleneck.   single - vehicle data generated by several virtual detectors show a semi - quantitative agreement with microscopic data from the dutch freeway a9.   this includes the observed distributions of the net time headways and times - to - collision for free and congested traffic.   while the times - to - collision show a nearly universal distribution in free and congested traffic, the modal value of the time headway distribution is shifted by a factor of about two in congested conditions.   macroscopically, this corresponds to the capacity drop at the transition from free to congested traffic.   finally, we explain the wide scattering of one - minute flow - density data by a self - organized variance - driven process that leads to the spontaneous formation and decay of long - lived platoons even for deterministic dynamics on a single lane.
i sketch what it is supposed to mean to quantize gauge theory, and how this can be made more concrete in perturbation theory and also by starting with a finite - dimensional lattice approximation. based on real experiments and computer simulations, quantum gauge theory in four dimensions   is believed to have a mass gap.   this is one of the most fundamental facts that makes the universe the way it is.   this article is the written form of a lecture presented at the conference `` geometric analysis : past and future '' ( harvard university, august 27-september 1, 2008 ), in honor of the 60th birthday of s.-   t.  .        epsf
we calculate the inelastic scattering probabilities in the wide band limit of a local polaron model with quadratic coupling to bosons.   the central object is a two - particle green function which is calculated exactly using a purely algebraic approach.   compared with the usual linear interaction term a quadratic interaction term gives higher probabilities for inelastic scattering involving a large number of bosons. as an application we consider the problem hot electron mediated energy transfer at surfaces and use the delta self - consistent field extension of density functional theory to calculate and compare coupling parameters and probabilities for exciting different vibrational modes of co adsorbed on a cu(100 ) surface
properties of the self - adjusted monte carlo algorithm applied to 2d  ising ferromagnet are studied numerically. the endogenous feedback form expressed in terms of the instant running averages   is suggested in order to generate a biased random walk of the temperature that converges to criticality without an external tuning.   the robustness of a stationary regime with respect to partial accessibility of the information is demonstrated.   several statistical and scaling aspects have been identified which allow to establish an alternative spin lattice model of the financial market.   it turns out that our model alike model suggested by s.  bornholdt, int.   j.  mod.   phys.   c * 12 * ( 2001 ) 667, may be described by lvy - type stationary distribution of feedback variations with unique exponent @xmath0.   however, the differences reflected by hurst exponents suggest that resemblances between the studied models seem to be nontrivial.   ,    monte carlo, self - adjusted parameters, econophysics, portfolio diversification, lvy distribution : 02.70.uu, 05.50.+q, 89.65.gh, 05.65.+b
complex structures on a material surface can significantly reduce total secondary electron emission from that surface.   a velvet is a surface that consists of an array of vertically standing whiskers.   the reduction occurs due to the capture of low - energy, true secondary electrons emitted at the bottom of the structure and on the sides of the velvet whiskers.   we performed numerical simulations and developed an approximate analytical model that calculates the net secondary electron emission yield from a velvet surface as a function of the velvet whisker length and packing density, and the angle of incidence of primary electrons.   the values of optimal velvet whisker packing density that maximally suppresses secondary electron emission yield are determined as a function of velvet aspect ratio and electron angle of incidence.   pacs : 52.59.bi, 52.59.fn, 52.77.-j
since the introduction of the black - scholes model stochastic processes have played an increasingly important role in mathematical finance. in many cases prices, volatility and other quantities can be modeled using stochastic ordinary differential equations.   available methods for solving such equations have until recently been markedly inferior to analogous methods for deterministic ordinary differential equations.   recently, a number of methods which employ variable stepsizes to control local error have been developed which appear to offer greatly improved speed and accuracy.   here we conduct a comparative study of the performance of these algorithms for problems taken from the mathematical finance literature.
measuring the evolution in the clustering of galaxies over a large redshift range is a challenging problem.   for a two - dimensional galaxy catalog, however, we can measure the galaxy - galaxy angular correlation function which provides information on the density distribution of galaxies. by utilizing photometric redshifts  , we can measure the angular correlation function in redshift shells ( brunner 1997, connolly _   et al. _   1998 ) which minimizes the galaxy projection effect, and allows for a measurement of the evolution in the correlation strength with redshift. in this proceedings  , we present some preliminary results which extend our previous work using more accurate photometric redshifts, and also incorporate absolute magnitudes, so that we can measure the evolution of clustering with either redshift or intrinsic luminosity.
we present a model for microwave photoconductivity in two - dimensional electron systems ( 2dess ) in a magnetic field at the microwave frequencies lower that the electron cyclotron frequency when the intra - landau level ( ll ) transitions dominate. using this model  , we explain the effect of decrease in the 2des dissipative conductivity ( and resistivity ) and smearing of its shubnikov  de haas oscillations by microwave radiation observed recently  @xcite.   the model invokes the concept of suppression of elastic impurity scattering of electrons by the microwave electric field.   we calculated the dependence of the 2des conductivity associated with intra - ll transitions as a function of the radiation and cyclotron frequencies and microwave power.   the obtained dependences are consistent with the results of recent experimental observations  @xcite.
large - scale faint structure detected by the recent observations in the halo of the andromeda galaxy ( m31 ) provides an attractive window to explore the structure of outer cold dark matter ( cdm ) halo in m31. using an @xmath0-body simulation of the interaction between an accreting satellite galaxy and m31, we investigate the mass density profile of the cdm halo.   we find the sufficient condition of the outer density profile of cdm halo in m31 to reproduce the andromeda giant stream and the shells at the east and west sides of m31.   the result indicates that the density profile of the outer dark matter halo of m31 is a steeper than the prediction of the theory of the structure formation based on the cdm model.
we give a closer look at the central limit theorem ( clt ) behavior in quasi - stationary states of the hamiltonian mean field model, a paradigmatic one for long - range - interacting classical many - body systems.   we present new calculations which show that, following their time evolution, we can observe and classify three kinds of long - standing quasi - stationary states ( qss ) with different correlations.   the frequency of occurrence of each class depends on the size of the system.   the different microsocopic nature of the qss leads to different dynamical correlations and therefore to different results for the observed clt behavior.   metastability in hamiltonian dynamics ; long - range interactions ; central limit theorem behavior ; nonextensive statistical mechanics.
it has been shown in our previous publication @xcite that high - viscosity drops in two dimensional linear creeping flows with a nonzero vorticity component may have two stable stationary states.   one state corresponds to a nearly spherical, compact drop stabilized primarily by rotation, and the other to an elongated drop stabilized primarily by capillary forces. here   we explore consequences of the drop bistability for the dynamics of highly viscous drops.   using both boundary - integral simulations and small - deformation theory we show that a quasi - static change of the flow vorticity gives rise to a hysteretic response of the drop shape, with rapid changes between the compact and elongated solutions at critical values of the vorticity. in flows with sinusoidal temporal variation of the vorticity we find chaotic drop dynamics in response to the periodic forcing.   a cascade of period - doubling bifurcations is found to be directly responsible for the transition to chaos. in random flows   we obtain a bimodal drop - length distribution.   some analogies with the dynamics of macromolecules and vesicles are pointed out.
a space - time symmetric and explicitly lorentz covariant path integral formalism of relativistic quantum mechanics is proposed, which produces partial locally correlations of quantum processes of massive particles with the velocity of light at low energy limits.   a superluminal correlation is also possible if anti - particles that moving along reverse time direction are excited.   this provides a new point of view to interpret epr experiments, also leaks a light of hope for hidden variable theories.
we elaborate the possibility for a deformed extra space to be considered as the dark matter candidate. to perform calculations a class of two - dimensional extra metrics   was considered in the framework of the multidimensional gravity.   it was shown that there exists a family of stationary metrics of the extra space possessing point - like defect.   estimation of cross section of scattering of a particle of the ordinary matter on a spatial domain with deformed extra space is in agreement with the observational constraints.
this review covers hot cores in the context of high - mass star formation. after giving an overview of chemical processes and diversity during high - mass star formation  , it reviews the ` warm envelope'phase which probably precedes the formation of hot cores.   some recent determinations of the cosmic - ray ionization rate are discussed, as well as recent evidence for hot cores around low - mass stars.   routes for future hot core research are outlined.
the framed little 2-discs operad is homotopy equivalent to the kimura - stasheff - voronov cyclic operad of moduli spaces of genus zero stable curves with tangent rays at the marked points and nodes.   we show that this cyclic operad is formal, meaning that its chains and its homology ( the batalin - vilkovisky operad ) are quasi - isomorphic cyclic operads.   to prove this we introduce a new complex of graphs in which the differential is a combination of edge deletion and contraction, and we show that this complex resolves bv as a cyclic operad.
we construct initial data for a particular class of brill wave metrics using regge calculus, and compare the results to a corresponding continuum solution, finding excellent agreement.   we then search for trapped surfaces in both sets of initial data, and provide an independent verification of the existence of an apparent horizon once a critical gravitational wave amplitude is passed.   our estimate of this critical value, using both the regge and continuum solutions, supports other recent findings.   laur-98 - 5276
among the most spectacular variable stars are the luminous blue variables ( lbvs ), which can show three types of variability. the lbv phase of evolution is poorly understood, and the driving mechanisms for the variability are not known. the most common type of variability, the s dor instability, occurs on timescales of tens of years   during an s dor outburst, the visual magnitude of the star increases, while the bolometric magnitude stays approximately constant. in this work, we investigate pulsation as a possible trigger for the s dor type outbursts.   we calculate the pulsations of envelope models using a nonlinear hydrodynamics code including a time - dependent convection treatment.   we initialize the pulsation in the hydrodynamic model based on linear non - adiabatic calculations.   pulsation properties for a full grid of models from 20 to 85 m@xmath0were calculated, and in this paper we focus on the few models that show either long - period pulsations or outburst - like behaviour, with photospheric radial velocities reaching 70 - 80 km / s. at the present time, our models can not follow mass loss, so once the outburst event begins, our simulations are terminated.   our results show that pulsations alone are not able to drive enough surface expansion to eject the outer layers  . however, the outbursts and long - period pulsations discussed here produce large variations in effective temperature and luminosity, which are expected to produce large variations in the radiatively driven mass - loss rates.   stars : massive  stars : oscillations
a new heuristic method for the evaluation of definite integrals is presented.   this _ method of brackets _ has its origin in methods developed for the evaluation of feynman diagrams.   we describe the operational rules and illustrate the method with several examples.   the method of brackets reduces the evaluation of a large class of definite integrals to the solution of a linear system of equations.            .   the work of the second author was partially funded by @xmath0. ]
a pair of two - level systems initially prepared in different thermal states and coupled to an external reversible work source, do not in general reach a common temperature at the end of a unitary work extraction process.   we define an effective temperature for the final nonequilibrium but passive state of the bipartite quantum system and analyse its properties.
we consider the metastable dynamics of a flattened dipolar condensate.   we develop an analytic model that quantifies the energy barrier to the system undergoing local collapse to form a density spike.   we also develop a stochastic gross - pitaevskii equation ( sgpe ) theory for a flatted dipolar condensate, which we use to perform finite temperature simulations verifying the local collapse scenario.   we predict that local collapses play a significant role in the regime where rotons are predicted to exist, and will be an important consideration for experiments looking to detect these excitations.
giant radio haloes in galaxy clusters are the primary evidence for the existence of relativistic particles ( cosmic rays ) and magnetic fields over mpc scales.   observational tests for the different theoretical models explaining their powering mechanism have so far been obtained through x - ray selection of clusters, e.g. by comparing cluster x - ray luminosities with radio halo power. here   we present the first global scaling relations between radio halo power and integrated sunyaev - zeldovich ( sz ) effect measurements, using the _ planck _ all - sky cluster catalog and published radio data.   the correlation agrees well with previous scaling measurements based on x - ray data, and offers a more direct probe into the mass dependence inside radio haloes.   however, we find no strong indication for a bi - modal cluster population split between radio halo and radio quiet objects. we discuss the possible causes for this apparent lack of bi - modality, and compare the observed slope of the radio - sz correlation with competing theoretical models of radio halo origin.       galaxies : clusters : intracluster medium  radiation mechanism : thermal  radiation mechanism : non - thermal  radio continuum : general
we describe the endomorphism rings of maximal rigid objects in the cluster categories of tubes.   moreover, we show that they are gentle and have gorenstein dimension 1.   we analyse their representation theory and prove that they are of finite type.   finally, we study the relationship between the module category and the cluster tube via the hom - functor.
we review the derivation of the metric for a spinning body of any shape and composition using linearized general relativity theory, and also obtain the same metric using a transformation argument.   the latter derivation makes it clear that the linearized metric contains only the eddington @xmath0 and @xmath1 parameters, so no new parameter is involved in frame  dragging or lense  thirring effects.   we then calculate the precession of an orbiting gyroscope in a general weak gravitational field, described by a newtonian potential ( the gravito - electric field ) and a vector potential ( the gravito - magnetic field ).   next we make a multipole analysis of the potentials and the precession equations, giving all of these in terms of the spherical harmonics moments of the density distribution. the analysis is not limited to an axially symmetric source,   although the earth, which is the main application, is very nearly axisymmetric  . finally we analyze the precession in regard to the gravity probe b ( gp - b ) experiment, and find that the effect of the earth s quadrupole moment ( @xmath2 ) on the geodetic precession is large enough to be measured by gp - b ( a previously known result ), but the effect on the lense  thirring precession is somewhat beyond the expected gp - b accuracy.
the effects of passive scalar anisotropy on subgrid - scale ( sgs ) physics and modeling for large - eddy simulations are studied experimentally.   measurements are performed across a moderate reynolds number wake flow generated by a heated cylinder, using an array of four x - wire and four cold - wire probes. by varying the separation distance among probes in the array, we obtain filtered and subgrid quantities at three different filter sizes.   we compute several terms that comprise the subgrid dissipation tensor of kinetic energy and scalar - variance and test for isotropic behavior, as a function of filter scale.   we find that whereas the kinetic energy dissipation tensor tends towards isotropy at small scales, the sgs scalar - variance dissipation remains anisotropic independent of filter scale.   the eddy - diffusion model predicts isotropic behavior, whereas the nonlinear ( or tensor eddy diffusivity ) model reproduces the correct trends, but overestimates the level of scalar dissipation anisotropy.   these results provide some support for so - called mixed models but raise new questions about the causes of the observed anisotropy.
we develop a method for calculating the norm and the spectrum of the modulus of a foguel operator. in many cases,   the norm can be computed exactly. in others,   sharp upper bounds are obtained. in particular, we observe several connections between foguel operators and the golden ratio.
the hypothesis that the magnetic catalysis of chiral symmetry breaking is due to interactions of massless fermions in their lowest landau level is examined in the context of chirally symmetric models with short ranged interactions.   it is argued that, when the magnetic field is sufficiently large, even an infinitesimal attractive interaction in the appropriate channel will break chiral symmetry.
evidence from numerical simulations suggest that the nature of dynamo transition changes from supercritical to subcritical as the magnetic prandtl number is decreased. to explore this interesting crossover   we first use direct numerical simulations to investigate the hysteresis zone of a subcritical taylor - green dynamo.   we establish that a well defined boundary exists in this hysteresis region which separates dynamo states from the purely hydrodynamic solution.   we then propose simple dynamo models which show similar crossover from supercritical to subcritical dynamo transition as a function of the magnetic prandtl number.   our models show that the change in the nature of dynamo transition is connected to the stabilizing or de - stabilizing influence of governing non - linearities.
this report deals with the preparation of a clean ta(110 ) surface, investigated by means of scanning tunneling microscopy / spectroscopy as well as by low - energy electron diffraction and auger electron spectroscopy.   the surface initially exhibits a surface reconstruction induced by oxygen contamination.   this reconstruction can be removed by annealing at high temperatures under ultrahigh vacuum conditions.   the reconstruction - free surface reveals a surface resonance at a bias voltage of about -500 mv.   the stages of the transformation are presented and discussed. in a next step,   fe islands were grown on top of ta(110 ) and investigated subsequently.   an intermixing regime was identified for annealing temperatures of ( 550  590 )  k.    ` scanning tunneling microscopy, scanning tunneling spectroscopy, tantalum, surface segregation, iron islands, growth study `
we analyze qcd and weinberg - type sum rules in a low - temperature pion gas using vector and axial - vector spectral functions following from the model - independent chiral - mixing scheme. toward this end   we employ recently constructed vacuum spectral functions with ground and first - excited states in both channels and a universal perturbative continuum ; they quantitatively describe hadronic @xmath0-decay data and satisfy vacuum sum rules.   these features facilitate the implementation of chiral mixing without further assumptions, and lead to in - medium spectral functions which exhibit a mutual tendency of compensating resonance and dip structures, suggestive for an approach toward structureless distributions. in the sum rule analysis  , we account for pion mass corrections, which turn out to be significant.   while the weinberg sum rules remain satisfied even at high temperatures, the numerical evaluation of the qcd sum rules for vector and axial - vector channels reveals significant deviations setting in for temperatures beyond @xmath1140mev, suggestive of additional physics beyond low - energy chiral pion dynamics.
consider a model of particles(nucleons ) which has a two - body interaction which leads to bound composites with saturation properties.   these properties are : all composites have the same density and the ground state energies of composites with @xmath0 nucleons are given by @xmath1 where @xmath2 and @xmath3 are positive constants.   @xmath2 represents a volume term and @xmath3 a surface tension term.   these values are taken from nuclear physics.   we show that in the large @xmath4 limit where @xmath4 is the number of particles such an assembly in a large enclosure at finite temperature shows properties of liquid - gas phase transition.   we do not use the two - body interaction but the gross properties of the composites only.   we show that ( a ) the @xmath5 isotherms show a region where pressure does not change as @xmath6 changes just as in maxwell construction of a van der waals gas, ( b ) in this region the chemical potential does not change and ( c ) the model obeys the celebrated clausius - clapeyron relations.   a scaling law for the yields of composites emerges.    for a finite number of particles @xmath4 ( upto some thousands )   the problem can be easily solved on a computer.   this allows us to study finite particle number effects which modify phase transition effects.   the model is calculationally simple.   monte - carlo simulations are not needed.
we study the dynamics of polariton condensate wave trains that propagate along a quasi one - dimensional waveguide. through the application of tuneable potential barriers the propagation   can be reflected and multiple reflections used to confine and store a propagating state.   energy - relaxation processes allow the delayed relaxation into a long - living coherent ground state.   aside the potential routing of polariton condensate signals, the system forms an and - type logic gate compatible with incoherent inputs.
if susy provides a solution to the hierarchy problem then supersymmetric states should not be too heavy.   this requirement is quantified by a fine tuning measure that provides a quantitative test of susy as a solution to the hierarchy problem.   the measure is useful in correlating the impact of the various experimental measurements relevant to the search for supersymmetry and also in identifying the most sensitive measurements for testing susy. in this paper   we apply the measure to the cmssm, computing it to two - loop order and taking account of current experimental limits and the constraint on dark matter abundance. using this   we determine the present limits on the cmssm parameter space and identify the measurements at the lhc that are most significant in covering the remaining parameter space. without imposing the lep higgs mass bound we show that the smallest fine tuning ( 1:13 ) consistent with a relic density within the wmap bound corresponds to a higgs mass of 114@xmath02 gev.   fine tuning rises rapidly for heavier higgs.   outp-0924p + cern - ph - th-2009 - 209    * testing susy *    * s. cassel@xmath1, d.  m. ghilencea@xmath2, g. g. ross@xmath3 * +   +  @xmath4 department of physics, cern - theory division, ch-1211 geneva 23, switzerland.
we investigate properties of @xmath0-modes characterized by regular eigenvalue problem in slowly rotating relativistic polytropes.   our numerical results suggest that discrete @xmath0-mode solutions for the regular eigenvalue problem exist only for restricted polytropic models.   in particular the @xmath0-mode associated with @xmath1, which is considered to be the most important for gravitational radiation driven instability, do not have a discrete mode as solutions of the regular eigenvalue problem for polytropes having the polytropic index @xmath2 even in the post - newtonian order.   furthermore for a @xmath3 polytrope, which is employed as a typical neutron star model, discrete @xmath0-mode solutions for regular eigenvalue problem do not exist for stars whose relativistic factor @xmath4 is larger than about @xmath5. here   @xmath6 and @xmath7 are stellar mass and stellar radius, respectively.
we present new evolutionary models for zero - metallicity stars, covering a large range of initial masses ( from 0.8 to 100 @xmath0 ).   models are computed with overshooting from stellar cores and convective envelopes, and assuming mass - loss from the most massive stars.   we discuss the main evolutionary features of these stars, and provide estimates of the amount of newly - synthesized elements dredged - up to the stellar surface, and possibly lost by stellar winds from the most massive stars.   full details of these models will be given in marigo et al.   ( 2000, in preparation ).
we present a general formulation of special - relativistic magnetohydrodynamics and derive exact radially self - similar solutions for axisymmetric outflows from strongly magnetized, rotating compact objects.   we generalize previous work by including thermal effects and analyze in detail the various forces that guide, accelerate, and collimate the flow.   we demonstrate that, under the assumptions of a quasi - steady poloidal magnetic field and of a highly relativistic poloidal velocity, the equations become effectively time - independent and the motion can be described as a frozen pulse.   we concentrate on trans - alfvnic solutions and consider outflows that are super - alfvnic throughout in the companion paper.   our results are applicable to relativistic jets in gamma - ray burst ( grb ) sources, active galactic nuclei, and microquasars, but our discussion focuses on grbs.   we envision the outflows in this case to initially consist of a hot and optically thick mixture of baryons, electron - positron pairs, and photons.   we show that the flow is at first accelerated thermally but that the bulk of the acceleration is magnetic, with the asymptotic lorentz factor corresponding to a rough equipartition between the poynting and kinetic - energy fluxes ( i.e., @xmath0 of the injected total energy is converted into baryonic kinetic energy ).   the electromagnetic forces also strongly collimate the flow, giving rise to an asymptotically cylindrical structure.
recent lattice results on qcd at finite temperatures and densities are reviewed.   two new and independent techniques give compatible results for physical quantities.   the phase line separating the hadronic and quark - gluon plasma phases, the critical endpoint and the equation of state are discussed.
a few characteristic exponents describing power law behaviors of roughness, coherence and persistence in stochastic time series are compared to each other.   relevant techniques for analyzing such time series are recalled in order to distinguish how the various exponents are measured, and what basic differences exist between each one.   financial time series, like the jpy / dem and usd / dem exchange rates are used for illustration, but mathematical ones, like ( fractional or not ) brownian walks can be used also as indicated.
we report lifetimes, branching fractions, and the resulting oscillator strengths for transitions within the p  ii multiplet ( 3@xmath03@xmath1 @xmath2 @xmath3 3@xmath03@xmath44@xmath5 @xmath6 ) at 1154 .   these beam - foil measurements represent the most comprehensive and precise set currently available experimentally.   comparison with earlier experimental and theoretical results is very good.   since morton s most recent compilation is based on the earlier body of results, phosphorus abundances for interstellar material in our galaxy and beyond derived from @xmath71154 do not require any revision.
we develop a quantisation scheme for maxwell s equations without source on an oriented 4-dimensional globally hyperbolic spacetime with at most finitely many connected components.   the field strength tensor is the key dynamical object and it is not assumed a priori that it descends from a vector potential. it is shown that, in general, the associated field algebra can contain a non trivial centre and, on account of this, such a theory can not be described within the framework of general local covariance unless further restrictive assumptions on the topology of the spacetime are made.
we study a quantum thermal engine model for which the heat transfer law is determined by einstein s theory of radiation.   the working substance of the quantum engine is assumed to be a two - level quantum systems of which the constituent particles obey maxwell - boltzmann(m.b. ), fermi - dirac(f.d. ) or bose - einstein(b.e. )   distributions respectively at equilibrium. the thermal efficiency and its bounds at maximum power of these models are derived and discussed in the long and short thermal contact time limits.   the similarity and difference between these models are discussed.   we also compare the efficiency bounds of this quantum thermal engine to those of its classical counterpart.
we present the results of a systematic search in @xmath0 years of _ rossi x - ray timing explorer _ all - sky monitor data for evidence of periodicities not reported by wen et al.   ( 2006 ).   two variations of the commonly used fourier analysis search method have been employed to achieve significant improvements in sensitivity.   the use of these methods and the accumulation of additional data have resulted in the detection of the signatures of the orbital periods of eight low - mass x - ray binary systems and of ten high - mass x - ray binaries not listed in the tables of wen et al.
we review the concept of support vector machines ( svms ) and discuss examples of their use.   one of the benefits of svm algorithms, compared with neural networks and decision trees is that they can be less susceptible to over fitting than those other algorithms are to over training.   this issue is related to the generalisation of a multivariate algorithm ( mva ) ; a problem that has often been overlooked in particle physics.   we discuss cross validation and how this can be used to improve the generalisation of a mva in the context of high energy physics analyses.   the examples presented use the toolkit for multivariate analysis ( tmva ) based on root and describe our improvements to the svm functionality and new tools introduced for cross validation within this framework.
recently @xmath0 data obtained from differential ages of galaxies have been proposed as a new geometrical probe of dark energy. in this paper   we use those data, combined with other background tests ( cmb shift and snia data ), to constrain a set of general relativistic dark energy models together with some other models motivated by extra dimensions.   our analysis rests mostly on bayesian statistics, and we conclude that lcdm is at least substantially favoured, and that extradimensional models are less favoured than general relativistic ones.
gravitational waveforms and fluxes from extreme mass  ratio inspirals can be computed using time   domain methods with accuracy that is fast approaching that of frequency  domain methods.   we study in detail the computational efficiency of these methods for equatorial orbits of fast spinning kerr black holes, and find the number of modes needed in either method as functions of the orbital parameters in order to achieve a desired accuracy level.   we then estimate the total computation time and argue that for high eccentricity orbits the time   domain approach is more efficient computationally.   we suggest that in practice low@xmath0 modes are computed using the frequency   domain approach, and high@xmath0 modes are computed using the time   domain approach, where @xmath0 is the azimuthal mode number.
we study spiral galaxies using a simple global disk model as a mean for approximate determination of mass profiles. based on rotation curves and the amount of gas ( hi+he )  , we find global surface mass densities consistent with the measurements and compare them with b - band surface brightness profiles. as a result   we obtain mass - to - light ratio profiles.   we give some arguments for why our approach is reliable and sometimes better than those assuming ad hoc the presence of massive non - baryonic dark matter halo. with this model, we study galaxies ngc 7793, ngc 1365, ngc 6946 and ugc 6446. based on things- rotation curve we study also galaxy ngc 4536 and compare the results with those we published elsewhere for the same galaxy.
we apply a simple statistical method ( derenzo & hildebrand 1969 ) to estimating the completeness of quasar surveys.   it requires that an area has been covered by two or more, preferably different, selection techniques.   we use three suitable data sets with separate selections from : variability and uv - excess ( 170 quasars ) ; objective prism and uv - excess ( 141 quasars ) ; multicolour and x - ray ( _ rosat, _ 19 quasars ).   we find that, for selection by uv - excess, the common limit of @xmath0 leads to losses of @xmath1, typically missing low - luminosity @xmath2 quasars, independently of redshift.   systematic incompleteness will therefore affect the new generation of large quasar surveys that select by @xmath3. by correcting for this incompleteness  , we find, from the first data set ( @xmath4 and @xmath5 ), that the evolution of the quasar luminosity function ( lf ) is best described by joint luminosity and density evolution.   when extrapolated to @xmath6, the lf matches that of local seyfert galaxies better than any previous determination.   the lf shows an increase in the number of low - luminosity quasars at low redshifts and of brighter quasars at intermediate redshifts, relative to the lf of boyle et al.   ( 1990 ).   this result is consistent with models in which quasars fade from an initial bright phase.   50w@xmath7     3.5inversion 1.1 3 december 1997
we propose a stochastic dynamic model of migration and economic aggregation in a system of employed ( immobile ) and unemployed ( mobile ) agents which respond to local wage gradients.   dependent on the local economic situation, described by a production function which includes cooperative effects, employed agents can become unemployed and vice versa.   the spatio - temporal distribution of employed and unemployed agents is investigated both analytically and by means of stochastic computer simulations.   we find the establishment of distinct economic centers out of a random initial distribution.   the evolution of these centers occurs in two different stages : ( i ) small economic centers are formed based on the positive feedback of mutual stimulation / cooperation among the agents, ( ii ) some of the small centers grow at the expense of others, which finally leads to the concentration of the labor force in different extended economic regions. this crossover to large - scale production is accompanied by an increase in the unemployment rate.   we observe a stable coexistence between these regions, although they exist in an internal quasistationary non - equilibrium state and still follow a stochastic eigendynamics.    _   keywords _ : agents, aggregation, economic geography, stochastic dynamics    * modelling migration and economic agglomeration + with active brownian particles * + frank schweitzer + _ institute of physics, humboldt university, + unter den linden 6, 10099 berlin, germany _ + e - mail : frank@physik.hu-berlin.de +
the electronic structure of diluted ( ga, mn)as magnetic semiconductors in the presence of as - antisites and magnetic disorder is studied within the framework of the local spin density approximation.   both the chemical and magnetic disorders are treated using the coherent potential approximation.   a ground state with partial disorder in the local moments and with a reduced total magnetic moment appears in the presence of as - antisites.   we first estimate the curie temperature @xmath0 from total energy differences between the ferromagnetic and the paramagnetic state by identifying these with the corresponding energy difference in a classical heisenberg model.   a more systematic approach within the framework of the mean - field approximation to estimate @xmath0 consists in an evaluation of the effective exchange fields acting on the magnetic moment at a given site.   the presence of as - antisites strongly reduces the curie temperature.   the results indicate that the effect of impurities on the electronic structure can not be neglected and influences the curie temperature non - negligibly.   a comparison of the calculated curie temperatures to existing experimental data indicates an increase of the donor concentration with the increase of the mn - content.
the current paradigm foresees that relativistic jets are launched as magnetically dominated flows, whose magnetic power is progressively converted to kinetic power of of the matter of the jet, until equipartition is reached.   therefore, at the end of the acceleration phase, the jet should still carry a substantial fraction ( @xmath0 half ) of its power in the form of a poynting flux.   it has been also argued that, in these conditions, the best candidate particle acceleration mechanism is efficient reconnection of magnetic field lines, for which it is predicted that magnetic field and accelerated relativistic electron energy densities are in equipartition. through the modeling of the jet   non  thermal emission, we explore if equipartition is indeed possible in bl lac objects, i.e. low  power blazars with weak or absent broad emission lines.   we find that one  zone models ( for which only one region is involved in the production of the radiation we observe ) the particle energy density is largely dominating ( by 12 orders of magnitude ) over the magnetic one. as a consequence,   the jet kinetic power largely exceeds the magnetic power.   instead, if the jet is structured ( i.e. made by a fast spine surrounded by a slower layer ), the amplification of the ic emission due to the radiative interplay between the two components allows us to reproduce the emission in equipartition conditions.   bl lac objects : general  radiation mechanisms : non - thermal  @xmath1rays : galaxies
a first adiabatic core is a transient object formed in the early phase of star formation.   the observation of a first core is believed to be difficult because of its short lifetime and low luminosity. on the basis of radiation hydrodynamic simulations,   we propose a novel theoretical model of first cores, exposed long - lifetime first core ( elf ). in the very low - mass molecular core  , the first core evolves slowly and lives longer than 10,000 years because the accretion rate is considerably low.   the evolution of elfs is different from that of ordinary first cores because radiation cooling has a significant effect there.   we also carry out radiation transfer calculation of dust - continuum emission from elfs to predict their observational properties.   elfs have slightly fainter but similar seds to ordinary first cores in radio wavelengths, therefore they can be observed.   although the probabilities that such low mass cores become gravitationally unstable and start to collapse are low, we still can expect that a considerable number of elfs can be formed because there are many low - mass molecular cloud cores in star - forming regions that can be progenitors of elfs.
linear receivers are often used to reduce the implementation complexity of multiple antenna systems. in a traditional linear receiver architecture,   the receive antennas are used to separate out the codewords sent by each transmit antenna, which can then be decoded individually.   although easy to implement, this approach can be highly sub - optimal when the channel matrix is near singular.   this paper develops a new linear receiver architecture that uses the receive antennas to create an effective channel matrix with integer - valued entries. rather than attempting to recover transmitted codewords   directly, the decoder recovers integer combinations of the codewords according to the entries of the effective channel matrix.   the codewords are all generated using the same linear code which guarantees that these integer combinations are themselves codewords.   if the effective channel is full rank, these integer combinations can then be digitally solved for the original codewords.   this paper focuses on the special case where there is no coding across transmit antennas. in this setting,   the integer - forcing linear receiver significantly outperforms traditional linear architectures such as the decorrelator and mmse receiver. in the high snr regime  , the proposed receiver attains the optimal diversity - multiplexing tradeoff for the standard mimo channel.   it is further shown that in an extended mimo model with interference, the integer - forcing linear receiver achieves the optimal generalized degrees - of - freedom.   mimo, linear receiver architectures, linear codes, lattice codes
the study of stellar oscillations - asteroseismology - has revolutionized our understanding of the physical properties of the sun and similar potential for other stars has been demonstrated in recent years. in particular  , asteroseismic studies can constrain the stellar size, temperature and composition, which are important parameters to our understanding of planetary structure and evolution.   this makes asteroseismology a very powerful tool to complement planetary transits. as an example  , the transit measurement alone does not give the radius of the planet unless the radius of the host star is known, which again requires a known distance to the system.   transit measurements will therefore often require additional measurements to establish the radius of the planet.   with asteroseismology we can determine the radius of a star to very high precision ( 23% ) using only the photometric transit measurements.   this will be very valuable for a mission such as kepler, which will produce photometric time series of very high quality.
we use the s - matrix formalism of bound - state qed to study the photon - atom scattering.   we find that the internal lines in feynman diagrams which describing the propagation of off - shell bound electrons provide the off - shell amplitudes of photons propagation in atoms phenomenally.   our work set up the connection between the property of feynman propagators in bound - state qed and the superluminal but casual propagating behavior of light in atomic media.   we also studied the relation between the bound - state qed and the widely used light - atom interacting model in quantum optics, and give the experimental condition where only the bound - state qed is valid.
a model of spontaneous wavefunction collapse, which is explicitly local and lorentz - invariant, is defined.   some of the predictions of the model for specific experimental situations are derived.   it is shown that, although incompatible collapses, e.g. on opposite sides of an epr - type of experiment, can occur, they will not persist in time and that eventually only compatible results will be obtained.   the probabilities of particular results, however, will in general not agree with the predictions of quantum theory.   we argue that it is unlikely that the deviations would have been seen in any experiment yet performed.   + and + euan j. squires
the results from a @xmath0 @xmath1 @xmath2 ( @xmath3 ) snapshot survey of post - agb objects are shown.   the aim of the survey is to complement existing @xmath3 images of ppn and to connect various types of nebulosities with physical and chemical properties of their central stars.   nebulosities are detected in 15 of 33 sources.   images and photometric and geometric measurements are presented. for sources with nebulosities   we see a morphological bifurcation into two groups, duplex and sole, as previous studies have found.   we find further support to the previous results suggesting that this dichotomy is caused by a difference in optical thickness of the dust shell.   the remaining 18 sources are classified as stellar post - agb objects, because our observations indicate a lack of nebulosity.   we show that some stellar sources may in fact be duplex or sole based on their infrared colors.   the cause of the differences among the groups are investigated.   we discuss some evidence suggesting that high progenitor - mass agb stars tend to become duplex post - agb objects.   intermediate progenitor - mass agb stars tend to be sole post - agb objects.   most of the stellar sources probably have low mass progenitors and do not seem to develop nebulosities during the post - agb phase and therefore do not become planetary nebulae.
we discuss the systematic decomposition of all dimension-7 ( @xmath0 ) lepton number violating operators.   these @xmath0 operators produce momentum enhanced contributions to the long - range part of the @xmath1 decay amplitude and thus are severely constrained by existing half - live limits. in our list of possible models one can find contributions to the long - range amplitude discussed previously in the literature, such as the left - right symmetric model or scalar leptoquarks, as well as some new models not considered before.   the @xmath0 operators generate majorana neutrino mass terms either at tree - level, 1-loop or 2-loop level.   we systematically compare constraints derived from the mass mechanism to those derived from the long - range @xmath1 decay amplitude and classify our list of models accordingly.   we also study one particular example decomposition, which produces neutrino masses at 2-loop level, can fit oscillation data and yields a large contribution to the long - range @xmath1 decay amplitude, in some detail.
recently, it was argued that a three - point susceptibility equal to the density derivative of the intermediate scattering function, @xmath0, enters into an expression for the divergent part of an integrated four - point dynamic density correlation function of a colloidal suspension [ berthier _ et al.   _, j. chem. phys. * 126 *, 184503 ( 2007 ) ].   we show that, within the mode - coupling theory, the equation of motion for @xmath1 is essentially identical as the equation of motion for the @xmath2 limit of the three - point susceptibility @xmath3 introduced by biroli _   et al. _   [ phys.   rev.   lett.   * 97 *, 195701 ( 2006 ) ].   we present a numerical solution of the equation of motion for @xmath1.   we also derive and numerically solve an equation of motion for the density derivative of the self - intermediate scattering function, @xmath4.   we contrast the wave vector dependence of @xmath1 and @xmath5.
we present a general self - consistent lepto / hadronic jet model for the non - thermal electromagnetic emission of microquasars.   the model is applied to the low - mass microquasar ( lmmq ) gx 339 - 4 and predicts its high - energy features.   we assume that both leptons and hadrons are accelerated up to relativistic energies by diffusive shock acceleration, and calculate their contribution to the electromagnetic spectrum through all main radiative processes.   the radiative contribution of secondary particles ( pions, muons and electron - positron pairs ) is included.   we use a set of simultaneous observations in radio and x - rays to constrain the model parameters and find the best fit to the data.   we obtain different spectral energy distributions that can explain the observations, and make predictions for the high - energy emission.   observations with gamma - ray instruments like fermi can be used to test the model and determine the proton content of the jets.   finally, we estimate the positron injection in the surrounding medium. our findings support the suggested association between lmmqs and the observed distribution of the 511 kev line flux observed by integral.       gamma - rays : theory  radiation mechanisms : non - thermal  x - rays : binaries  x - rays : individual : gx 339 - 4.
we study chemical reaction networks with discrete state spaces, such as the standard continuous time markov chain model, and present sufficient conditions on the structure of the network that guarantee the system exhibits an extinction event.   the conditions we derive involve creating a modified chemical reaction network called a domination - expanded reaction network and then checking properties of this network.   we apply the results to several networks including an envz - ompr signaling pathway in _   escherichia coli_. this analysis produces a system of equalities and inequalities which, in contrast to previous results on extinction events, allows algorithmic implementation.   such an implementation will be investigated in a companion paper where the results are applied to 458 models from the european bioinformatics institute s biomodels database  .             * keywords : * reaction network, reaction graph, extinction, stochastic process, petri net * ams subject classifications : * 92c42, 60j27
we show that the black hole solutions of the effective string theory action, where one - loop effects that couple the moduli to gravity via a term are taken into account, admit primary scalar hair.   the requirement of absence of naked singularities imposes an upper bound on the scalar charges.   # 1#2 c i u
we propose a tight - binding model to investigate electronic transport properties of single helical protein molecules incorporating both the helical symmetry and the possibility of multiple charge transfer pathways.   our study reveals that due to existence of both the multiple charge transfer pathways and helical symmetry, the transport properties are quite rigid under influence of environmental fluctuations which indicates that these biomolecules can serve as better alternatives in nanoelectronic devices than its other biological counterparts _ e.g. _, single - stranded dna.
we study the collective excitations of a neutral atomic bose - einstein condensate with gravity - like @xmath0 interatomic attraction induced by electromagnetic wave. using the time - dependent variational approach  , we derive an analytical spectrum for monopole and quadrupole mode frequencies of a gravity - like self - bound bose condensed state at zero temperature.   we also analyze the excitation frequencies of the thomas - fermi - gravity ( tf - g ) and gravity ( g ) regimes.   our result agrees excellently with that of giovanazzi _   et al_. , which is obtained within the sum - rule approach.   we also consider the vortex state.   we estimate the superfluid coherence length and the critical angular frequencies to create a vortex around the @xmath1-axis.   we find that the tf - g regime can exhibit the superfluid properties more prominently than the g - regime.   we find that the monopole mode frequency of the condensate decreases due to the presence of a vortex.
we study the temporal and energy spectral characteristics of the persistent black hole x - ray binary lmc  x1 using two _ xmm - newton _ and a _ suzaku _ observation.   we report the discovery of low frequency ( @xmath0 ) quasi - periodic oscillations ( qpos ).   we also report the variablity of the broad iron k@xmath1 line studied earlier with _   suzaku_. the qpos are found to be weak with fractional @xmath2 amplitude in the @xmath3 range and quality factor @xmath4.   they are accompanied by weak red noise or zero - centered lorentzian components with @xmath2 variability at the @xmath5 level.   the energy spectra consists of three varying components  multicolour disk blackbody ( @xmath6 ), high energy power - law tail ( @xmath7 ) and a broad iron line at @xmath8. the broad iron line, the qpo and the strong power - law component are not always present. the qpos and the broad iron line appear to be clearly detected in the presence of a strong power - law component.   the broad iron line is found to be weaker when the disk is likely truncated and absent when the power - law component almost vanished.   these results suggest that the qpo and the broad iron line together can be used to probe the dynamics of the accretion disk and the corona.       accretion, accretion discs, black hole physics, binaries : spectroscopic, stars : individual : lmc  x1, x - rays : stars.
the ams-02 experiment confirms the excess of positrons in cosmic rays ( crs ) for energy above 10 gev with respect to the secondary production of positrons in the interstellar medium.   this is interpreted as evidence of the existence of a primary source of these particles.   possible candidates are dark matter or astrophysical sources. in this work   we discuss the possible contribution due to pulsars and their nebulae.   our key assumption is that the primary spectrum of electrons and positrons at the source is the same of the well known photon spectrum observed from gamma - rays telescopes. using a diffusion model in the galaxy we propagate the source spectra up to the solar system.   we compare our results with the recent experiments and with the lis model.    to appear on the proceedings of the 14th icatpp conference on + astroparticle, particle, space physics and detectors + for physics applications, + villa olmo ( como, italy ), 2327 october, 2013, + to be published by world scientific ( singapore ).
baryon acoustic oscillations ( bao ) at low redshift provide a precise and largely model - independent way to measure the hubble constant, h@xmath0.   the 6df galaxy survey measurement of the bao scale gives a value of h@xmath1 km s@xmath2 mpc@xmath2, achieving a @xmath3 precision of 5%. with improved analysis techniques, the planned wallaby ( hi ) and taipan ( optical ) redshift surveys   are predicted to measure h@xmath0 to 13% precision.
relativistic mean - field theory with @xmath0 meson, nonlinear isoscalar self - interactions and isoscalar - isovector cross interaction terms with parametrizations obtained to reproduce dirac - brueckner - hartree - fock calculations for nuclear matter is used to study asymmetric nuclear matter properties in @xmath1-equilibrium, including hyperon degrees of freedom and ( hidden ) strange mesons.   influence of cross interaction on composition of hyperon matter and electron chemical potential is examined.   softening of nuclear equation of state by the cross interactions results in lowering of hyperonization, although simultaneously enhancing a hyperon - induced decrease of the electron chemical potential, thus indicating further shift of a kaon condensate occurence to higher densities.
we define thermodynamic configurations and identify two primitives of discrete quantum processes between configurations for which heat and work can be defined in a natural way.   this allows us to uncover a general second law for any discrete trajectory that consists of a sequence of these primitives, linking both equilibrium and non - equilibrium configurations.   moreover, in the limit of a discrete trajectory that passes through an infinite number of configurations, i.e. in the reversible limit, we recover the saturation of the second law.   finally, we show that for a discrete carnot cycle operating between four configurations one recovers carnot s thermal efficiency.
to show the feasibility of a long distance partial bell - state measurement, a hong - ou - mandel experiment with coherent photons is reported.   pairs of degenerate photons at telecom wavelength are created by parametric down conversion in a periodically poled lithium niobate waveguide.   the photon pairs are separated in a beam - splitter and transmitted via two fibers of 25 km.   the wave - packets are relatively delayed and recombined on a second beam - splitter, forming a large mach - zehnder interferometer.   coincidence counts between the photons at the two output modes are registered.   the main challenge consists in the trade - off between low count rates due to narrow filtering and length fluctuations of the 25 km long arms during the measurement. for balanced paths a hong - ou - mandel dip with a net visibility of 47.3 %   is observed, which is close to the maximal theoretical value of 50% developed here.   this proves the practicability of a long distance bell state measurement with two independent sources, as e.g. required in an entanglement swapping configuration in the scale of tens of km.
we numerically study dynamical behaviors of the quasiperiodically forced hodgkin - huxley neuron and compare the dynamical responses with those for the case of periodic stimulus. in the periodically forced case,   a transition from a periodic to a chaotic oscillation was found to occur via period doublings in previous numerical and experimental works.   we investigate the effect of the quasiperiodic forcing on this period - doubling route to chaotic oscillation.   in contrast to the case of periodic forcing, new type of strange nonchaotic ( sn ) oscillating states ( that are geometrically strange but have no positive lyapunov exponents ) are found to exist between the regular and chaotic oscillating states as intermediate ones.   their strange fractal geometry leads to aperiodic `` complex '' spikings.   various dynamical routes to sn oscillations are identified, as in the quasiperiodically forced logistic map.   these sn spikings are expected to be observed in experiments of the quasiperiodically forced squid giant axon.
consider the problem of a multiple - input multiple - output ( mimo ) multiple - access channel ( mac ) at the limit of large number of users. clearly, in practical scenarios, only a small subset of the users can be scheduled to utilize the channel simultaneously.   thus, a problem of user selection arises.   however, since solutions which collect channel state information ( csi ) from all users and decide on the best subset to transmit in each slot do not scale when the number of users is large, distributed algorithms for user selection are advantageous.    in this paper, we suggest a distributed user selection algorithm, which selects a group of users to transmit without coordinating between all users and without all users sending csi to the base station.   this threshold - based algorithm is analyzed for both zero - forcing ( zf ) and minimal mean square error ( mmse ) receivers, and its expected capacity in the limit of large number of users is investigated.   it is shown that for large number of users it achieves the same scaling laws as the optimal centralized scheme.   multi - stage distributed schemes are also considered and shown to be advantageous in practical scenarios.   = 1
using first - principle plane wave method we investigate the effects of static charging on structural, electronic and magnetic properties of suspended, single layer graphene, graphane, fluorographene, bn and mos@xmath0 in honeycomb structure.   the limitations of periodic boundary conditions in the treatment of negatively charged layers are clarified. upon positive charging the band gaps between the conduction and valence bands increase, but the single layer nanostructures become metallic owing to the fermi level dipping below the maximum of valence band. moreover, their bond lengths increase leading to phonon softening. as a result, the frequencies of raman active modes are lowered.   high level of positive charging leads to structural instabilities in single layer nanostructures, since their specific phonon modes attain imaginary frequencies.   similarly, excess positive charge is accumulated at the outermost layers of metallized bn and mos@xmath0 sheets comprising a few layers.   once the charging exceeds a threshold value the outermost layers are exfoliated.   charge relocation and repulsive force generation are in compliance with classical theories.
we use molecular dynamics simulations to investigate the tracer diffusion in a sea of polymers with specific binding zones for the tracer. these binding zones act as traps.   our simulations show that the tracer can undergo normal yet non - gaussian diffusion under certain circumstances, e.g, when the polymers with traps are frozen in space and the volume fraction and the binding strength of the traps are moderate. in this case, as the tracer moves, it experiences a heterogeneous environment and exhibits confined continuous time random walk ( ctrw ) like motion resulting a non - gaussian behavior.   also the long time dynamics becomes subdiffusive as the number or the binding strength of the traps increases.   however, if the polymers are mobile then the tracer dynamics is gaussian but could be normal or subdiffusive depending on the number and the binding strength of the traps.   in addition, with increasing binding strength and the number of the polymer traps, the probability of the tracer being trapped increases. on the other hand, removing the binding zones does not result trapping, even at comparatively high crowding.   our simulations also show that the trapping probability increases with the increasing size of the tracer and for a bigger tracer with the frozen polymer background the dynamics is only weakly non - gaussian but highly subdiffusive.   our observations are in the same spirit as found in many recent experiments on tracer diffusion in polymeric materials and questions the validity of gaussian theory to describe diffusion in crowded environment in general.
the nondetection of neutrinos coming from gamma ray bursts ( grbs ) by the icecube experiment has raised serious questions on our understanding of grb s and the mechanism of neutrino flux production in them.   motivated by this and the need for a precise calculation for grb neutrino flux, here we study the effects of beyond standard model physics on the grb neutrino flux. in the internal shock model of grb, high energy neutrinos are expected from muon, pion and kaon decays. using the latest best fit neutrino oscillation parameters, we compute the expected flux on earth for standard as well as non - standard oscillation scenarios. among the non - standard scenarios, we consider neutrino decay, pseudo - dirac nature of neutrinos and presence of one ev scale light sterile neutrino. incorporating other experimental bounds on these new physics scenarios,   we show that neutrino decay scenario can significantly alter the neutrino flux on earth from the expected ones whereas the corresponding changes for pseudo - dirac and sterile neutrino cases are moderate.
a tendency for the axes of double - lobed radio quasars to be aligned with the electric vectors of optical polarization in the active galactic nuclei is well - known.   however, the origin of the polarization and reason behind its correlation with radio morphology is not yet established. from accurate spectropolarimetry of 7 quasars which show this alignment effect, we find that the polarization is universally confined to the continuum, and not shared by the line emission or 3000    bump. over the observed region   @xmath0  , the spectral indices of polarized flux, @xmath1, are consistent with uniform polarization applied to the light of the big blue bump or with synchrotron emission.   however, electron scattering from an optically - thick, geometrically - thin, accretion disk is well - known to give rise to a polarization position angle that is perpendicular to the disk axis.   optical synchrotron emission akin to that shown to exist in the miniblazar 3c  273 is a more attractive explanation, and supporting evidence can be found for some of the targets in the form of polarimetric variability over intervals of years.   properties of the most strongly - polarized radio - optical aligned quasars can be explained by misdirected blazar core components that have net polarizations of @xmath2% and provide @xmath310% of the total optical light.
we report on a multiwavelength survey of a sample of 42 flat - spectrum radio - loud narrow - line seyfert 1 galaxies ( rlnls1s ).   this is the largest known sample of this type of active galactic nucleus ( agn ) to date.   we found that 17% of sources were detected at high - energy gamma rays ( @xmath0  mev ), and 90% at x - rays ( @xmath1  kev ).   the masses of the central black holes are in the range @xmath2, smaller than the values of blazars.   the disk luminosities are about @xmath3% of the eddington value, with one outlier at 0.3%, comparable with the luminosities observed in flat - spectrum radio quasars ( fsrqs ). the jet powers are @xmath4  erg  s@xmath5, comparable with bl lac objects, yet relatively smaller than fsrqs. however, once renormalized by the mass of the central black hole, the jet powers of rlnls1s, bl lacs, and fsrqs are consistent each other, indicating the scalability of the jets.   we found episodes of extreme variability at high energies on time scales of hours. in some cases,   dramatic spectral and flux changes are interpreted as the interplay between the relativistic jet and the accretion disk.   we conclude that, despite the distinct observational properties, the central engines of rlnls1s are similar to those of blazars.    1.0 cm
we report on our investigation of the crystal structure of arsenic under compression, focusing primarily on the pressure - induced a7  @xmath0  simple cubic ( sc ) phase transition.   the two - atom rhombohedral unit cell is subjected to pressures ranging from 0  gpa to 200  gpa ; for each given pressure, cell lengths and angles, as well as atomic positions, are allowed to vary until the fully relaxed structure is obtained.   we find that the nearest and next - nearest neighbor distances give the clearest indication of the occurrence of a structural phase transition.   calculations are performed using the local density approximation ( lda ) and the pbe and pw91 generalized gradient approximations ( gga - pbe and gga - pw91 ) for the exchange - correlation functional.   the a7  @xmath0  sc transition is found to occur at 21@xmath11  gpa in the lda, at 28@xmath11  gpa in the gga - pbe and at 29@xmath11  gpa in the gga - pw91 ; no volume discontinuity is observed across the transition in any of the three cases.   we use grids as dense as 66@xmath266@xmath266 to enable us to present reliably converged results for the a7  @xmath0  sc transition of arsenic.   o v u
we investigate the imprint of reheating on the gravitational wave spectrum produced by self - ordering of multi - component scalar fields after a global phase transition.   the equation of state of the universe during reheating, which usually has different behaviour from that of a radiation - dominated universe, affects the evolution of gravitational waves through the hubble expansion term in the equations of motion.   this gives rise to a different power - law behavior of frequency in the gravitational wave spectrum.   the reheating history is therefore imprinted in the shape of the spectrum.   we perform @xmath0 lattice simulations to investigate how the ordering scalar field reacts to the change of the hubble expansion and how the reheating effect arises in the spectrum.   we also compare the result with inflation - produced gravitational waves, which has a similar spectral shape, and discuss whether it is possible to distinguish the origin between inflation and global phase transition by detecting the shape with future direct detection gravitational wave experiments such as decigo.
we analyze structure of the world foreign currency exchange ( fx ) market viewed as a network of interacting currencies.   we analyze daily time series of fx data for a set of 63 currencies, including gold, silver and platinum.   we group together all the exchange rates with a common base currency and study each group separately. by applying the methods of filtered correlation matrix we identify clusters of closely related currencies.   the clusters are formed typically according to the economical and geographical factors.   we also study topology of weighted minimal spanning trees for different network representations ( i.e., for different base currencies ) and find that in a majority of representations the network has a hierarchical scale - free structure.   in addition, we analyze the temporal evolution of the network and detect that its structure is not stable over time.   a medium - term trend can be identified which affects the usd node by decreasing its centrality.   our analysis shows also an increasing role of euro in the world s currency market.
we report the results from a detailed analysis of an archival xmm - newton observation of the x - ray source xgps - i j183251 - 100106, which has been suggested as a promising magnetic cataclysmic variable candidate based on its optical properties.   a single periodic signal of @xmath0  hrs is detected from all epic cameras on board xmm - newton.   the phase - averaged x - ray spectrum can be well - modeled with a thermal bremsstrahlung of a temperature @xmath1  kev.   both x - ray spectral and temporal behavior of this system suggest it as a eclipsing cataclysmic variable of am herculis ( or polar ) type.
in this paper we briefly comment on the observational status of the possible physical association between unidentified egret sources and supernova remnants ( snrs ) in our galaxy.   we draw upon recent results presented in the review by torres et al.   ( physics reports, 2003 ), concerning molecular gas in the vicinity of all 19 snrs found to be positionally coincident with egret sources at low galactic latitudes.   in addition, we present new results regarding the supernova remnant cta  1.   our findings disfavor the possibility of a physical connection with the nearby ( in projection ) egret source.   there remains possible, however, that the compact object produced in the supernova explosion be related with the observed @xmath0-ray flux.
the evaporation residue of barium isotopes are investigated in a microscopic study using relativistic mean field theory.   the investigation includes the isotopes of barium from the valley of stability to exotic proton - rich region.   the ground as well as neck configurations for these nuclei are generated from their total nucleonic density distributions of the corresponding state.   we have estimated the constituents ( number of nucleons ) in the elongated neck region of the fission state.   we found the @xmath0-particle as the constituent of neck of ba - isotopes, referred to as the evaporated residue in heavy - ion reaction studies. a strong correlation between the neutron and proton is observed throughout the isotopic chain.
we develop a model for visible matter - dark matter interaction based on the exchange of a massive gray boson called herein the mulato.   our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter.   we postulate six families of particles five of which are dark.   this leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds.   a close study of big bang nucleosynthesis ( bbn ), baryon asymmetries, cosmic microwave background ( cmb ) bounds, galaxy dynamics, together with the standard model assumptions, help us to set a limit on the mass and width of the new gauge boson.   modification of the statistics underlying the kinetic energy distribution of particles during the bbn is also discussed.   the changes in reaction rates during the bbn due to a departure from the debye - hueckel electron screening model is also investigated.
we have been evaluated some observables of n - d systems by using pionless effective field theory(eft(@xmath0 ) ) and insertion of the three - body force up to next - to - next to leading order(n@xmath1lo ).   the evaluated data has been compared with experimental and the three - nucleon calculation of the total cross section with modern realistic two- and three - nucleon forces av18/urbix potential models calculations.
we consider @xmath0 dimensional gravity with a cosmological constant, and explore a duality that exists between space - times that have the de sitter group @xmath1 as its local isometry group.   in particular, the lorentzian theory with a positive cosmological constant is dual to the euclidean theory with a negative cosmological constant.   we use this duality to construct a mapping between apparently unrelated space - times.   more precisely, we exhibit a relation between the euclidean btz family and some @xmath2-cosmological solutions, and between de - sitter point particle space - times and the analytic continuations of anti - de sitter point particles.   we discuss some possible applications for bh and @xmath3 thermodynamics.   = cmff10 scaled1    o
the interaction of a weakly bound rydberg electron with an electromagnetic half - cycle pulse ( hcp ) is described with the help of a multidimensional semiclassical treatment.   this approach relates the quantum evolution of the electron to its underlying classical dynamics.   the method is nonperturbative and is valid for arbitrary spatial and temporal shapes of the applied hcp. on the basis of this approach angle- and   energy - resolved spectra resulting from the ionization of rydberg atoms by hcps are analyzed.   the different types of spectra obtainable in the sudden - impact approximation are characterized in terms of the appearing semiclassical scattering phenomena.   typical modifications of the spectra originating from finite pulse effects are discussed.
we investigate and compare different optical probes of a condensed state of microcavity polaritons in expected experimental conditions of non - resonant pumping.   we show that the energy- and momentum - resolved resonant rayleigh signal provide a distinctive probe of condensation as compared to, e.g., photoluminescence emission.   in particular, the presence of a collective sound mode both above and below the chemical potential can be observed, as well as features directly related to the density of states of particle - hole like excitations. both resonant rayleigh response and the absorption and photoluminescence,   are affected by the presence of quantum well disorder, which introduces a distribution of oscillator strengths between quantum well excitons at a given energy and cavity photons at a given momentum. as we show  , this distribution makes it important that in the condensed regime, scattering by disorder is taken into account to all orders.   we show that, in the low density linear limit, this approach correctly describes inhomogeneous broadening of polaritons.   in addition, in this limit, we extract a linear blue - shift of the lower polariton versus density, with a coefficient determined by temperature and by a characteristic disorder length.
we examine the role of resonant coupled channel final state interactions ( fsi ), as well as weak annihilation and exchange contributions in explaining all the two body hadronic @xmath0 decay modes data. in the un - unitarized amplitudes we include   modified wilson coefficients with non - factorizable corrections as parameters. for the hadronic form factors,   the z - series expansion method is used to get the @xmath1 dependence.   the fsi effects are incorporated via a phenomenological approach with widths of resonances to various channels taken from observations where available, and others as additional parameters to be determined from fits of all the theoretical rates to the measured ones.   our results for the rather hard to explain @xmath2 are in agreement with measured values.   we demonstrate that both weak exchange as well as fsi effects are required to get the correct branching ratio for the @xmath3 mode. using our unitarized amplitudes   we evaluate the strong phase difference between the amplitudes for @xmath4 and @xmath5 and find it to be in complete agreement with the recent bes iii result.
quantum oscillations in the binary antiferromagnetic metal feas are presented and compared to theoretical predictions for the electronic band structure in the anomalous spin density wave state of this material. demonstrating a new method for growing single crystals out of bi flux  , we utilize the highest quality feas to perform torque magnetometry experiments up to 35 t, using rotations of field angle in two planes to provide evidence for one electron and one hole band in the magnetically ordered state.   the resulting picture agrees with previous experimental evidence for multiple carriers at low temperatures, but the exact fermi surface shape disagrees with predictions, suggesting correlations play a role in deviation from ab initio theory and cause up to a four - fold enhancement in the effective electron mass.   = 1
the stationary thermionic electron emission currents from heated metals are compared against an analytical expression derived using a non equilibrium quantum kappa energy distribution for the electrons.   this later depends on the temperature decreasing parameter @xmath0 which can be estimated from the raw experimental data and characterizes the departure of the electron energy spectrum from the equilibrium fermi - dirac statistics.   the calculations accurately predict the measured thermionic emission currents for both high and moderate temperature ranges.   the richardson - dushman law governs the electron emission for large values of kappa or equivalently, for moderate metal temperatures. the high energy tail in the electron energy distribution function which develops at higher temperatures or lower kappa parameters, increases the emission currents well over the predictions of the classical expression.   this analysis also permits the quantitative estimation of the departure of the metal electrons from the equilibrium fermi - dirac statistics.
a monte carlo simulation study of the vacancy - assisted domain - growth in asymmetric binary alloys is presented.   the system is modeled using a three - state abv hamiltonian which includes an asymmetry term, not considered in previous works.   our simulated system is a stoichiometric two - dimensional binary alloy with a single vacancy which evolves according to the vacancy - atom exchange mechanism.   we obtain that, compared to the symmetric case, the ordering process slows down dramatically. concerning the asymptotic behavior it is algebraic and characterized by the allen - cahn growth exponent @xmath0.   the late stages of the evolution are preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy.   the results are discussed and compared to those obtained for the symmetric case.   # 1@xmath1#1
multidimensional reactive flow models of accreted hydrogen rich envelopes on top of degenerate cold white dwarfs are very effective tools for the study of critical, non spherically symmetric, behaviors during the early stages of nova outbursts.   such models can shed light both on the mechanism responsible for the heavy element enrichment observed to characterize nova envelope matter and on the role of perturbations during the early stages of ignition of the runaway.   the complexity of convective reactive flow in multi - dimensions makes the computational model itself complex and sensitive to the details of the numerics. in this study  , we demonstrate that the imposed outer boundary condition can have a dramatic effect on the solution.   several commonly used choices for the outer boundary conditions are examined.   it is shown that the solutions obtained from lagrangian simulations, where the envelope is allowed to expand and mass is being conserved, are consistent with spherically symmetric solutions. in eulerian schemes which utilize an outer boundary condition of free outflow, the outburst can be artificially quenched.
based on the generalized uncertainty principle ( gup ), proposed by some approaches to quantum gravity such as string theory and doubly special relativity theories, we investigate the effect of gup on the thermodynamic properties of compact stars with two different components.   we note that the existence of quantum gravity correction tends to resist the collapse of stars if the gup parameter @xmath0 is taking values between planck scale and electroweak scale. comparing with approaches  , it is found that the radii of compact stars are found smaller. increasing energy almost exponentially decreases the radii of compact stars.
we use our recently proposed accelerated dynamics algorithm @xcite to calculate temperature and stress dependence of activation free energy for surface nucleation of dislocations in pristine gold nanopillars under realistic loads.   while maintaining fully atomistic resolution, we achieve the fraction of a second time - scale regime.   we find that the activation free energy depends significantly and non - linearly on the driving force ( stress or strain ) and temperature, leading to very high activation entropies.   we also perform compression tests on gold nanopillars for strain rates varying between 7 orders of magnitudes, reaching as low as @xmath0.   our calculations bring out the perils of high strain - rate molecular dynamics calculations : we find that while the failure mechanism for @xmath1 compression of gold nanopillars remains the same across the entire strain - rate range, the elastic limit ( defined as stress for nucleation of the first dislocation ) depends significantly on the strain - rate.   we also propose a new methodology that overcomes some of the limits in our original accelerated dynamics scheme ( and accelerated dynamics methods in general ).   we lay out our methods in sufficient details so as to be used for understanding and predicting deformation mechanism under realistic driving forces for various problems.   dislocations, molecular dynamics, atomistic simulation, nucleation, activation energy, accelerated dynamics, nanomechanics
when a harmonic oscillator is under the influence of a gaussian process such as linear damping, parametric gain, and linear coupling to a thermal environment, its coherent states are transformed into states with gaussian wigner function.   qubit states can be encoded in the @xmath0 and @xmath1 fock states of a quantum harmonic oscillator, and it is relevant to know the fidelity of the output qubit state after a gaussian process on the oscillator. in this paper   we present a general expression for the average qubit fidelity in terms of the first and second moments of the output from input coherent states subjected to gaussian processes.
the existence of a minimal and fundamental length scale, say, the planck length, is a characteristic feature of almost all the models of quantum gravity.   the presence of the fundamental length is expected to lead to an improved ultra - violet behavior of the semi - classical propagators.   the hypothesis of path integral duality provides a prescription to evaluate the modified propagator of a free, quantum scalar field in a given spacetime, taking into account the existence of the fundamental length in a locally lorentz invariant manner.   we use this prescription to compute the quantum gravitational modifications to the propagators in spacetimes with constant curvature, and show that : ( i )  the modified propagators are ultra - violet finite, and ( ii )  the modifications are non - perturbative in the planck length.   we discuss the implications of our results.
the only evidence we have for a discrete reality comes from quantum measurements ; without invoking these measurements, quantum theory describes continuous entities.   this seeming contradiction can be resolved via analysis that treats measurements as boundary constraints.   it is well - known that boundaries can induce apparently - discrete behavior in continuous systems, and strong analogies can be drawn to the case of quantum measurement.   if quantum discreteness arises in this manner, this would not only indicate an analog reality, but would also offer a solution to the so - called `` measurement problem ''.
we present a classical analysis of the transient response of josephson junctions perturbed by microwaves and thermal fluctuations.   the results include a specific low frequency modulation in phase and amplitude behavior of a junction in its zero - voltage state.   this transient modulation frequency is linked directly to an observed variation in the probability for the system to switch to its non - zero voltage state. complementing previous work on linking classical analysis to the experimental observations of rabi - oscillations  , this expanded perturbation method also provides closed form analytical results for attenuation of the modulations and the rabi - type oscillation frequency.   results of perturbation analysis are compared directly ( and quantitatively ) to numerical simulations of the classical model as well as published experimental data, suggesting that transients to phase - locking are closely related to the observed oscillations.
in this paper we lay out a simple set of relationships connecting the dynamics of fast plasma jets to the dynamical state of their ambient media.   the objective is to provide a tool kit that can be used to connect the morphologies of radio agns in galaxy clusters to the dynamical state of the local icm.   the formalism is intended to apply to jets whether they are relativistic or non - relativistic.   special attention is paid to interactions involving icm shocks, although the results can be applied more broadly.   our formalism emphasizes the importance of the relative mach number of the impacting icm flow and the internal mach number of the agn jet in determing how the agn outflows evolve.
twisted light is light carrying orbital angular momentum.   the profile of such a beam is a ring - like structure with a node at the beam axis, where a phase singularity exists. due to the strong spatial inhomogeneity the mathematical description of twisted - light   matter interaction is non - trivial, in particular close to the phase singularity, where the commonly used dipole - moment approximation can not be applied. in this paper   we show that, if the handedness of circular polarization and the orbital angular momentum of the twisted - light beam have the same sign, a hamiltonian similar to the dipole - moment approximation can be derived.   however, if the signs differ, in general the magnetic parts of the light beam become of significant importance and an interaction hamiltonian which only accounts for electric fields is inappropriate.   we discuss the consequences of these findings for twisted - light excitation of a semiconductor nanostructures, e.g., a quantum dot, placed at the phase singularity.
for nearly two centuries the dynamics of chains have offered examples of paradoxical theoretical predictions. here   we propose a theory for the dissipative dynamics of one - dimensional continua with singularities which provides a unified treatment for chain problems that have suffered from paradoxical solutions.   these problems are duly solved within the present theory and their paradoxes removed  we hope.
current searches for direct production of scalar top quarks, or stops, in supersymmetry focus on their decays into @xmath0 by way of @xmath1 and @xmath2.   while the polarization of the top quark depends on the stop mixing, the chargino turns out to be fully polarized when the bottom yukawa coupling can be neglected relative the top yukawa coupling.   we compute the energy and angular spectra of the charged lepton in the chargino channel, which could serve as the spin - analyzer of the chargino.   in addition, we demonstrate the top polarization could have a significant impact on the selection efficiencies in direct stop samples at the lhc, while the effect from the chargino polarization is less pronounced.   two observables in the laboratory frame, the opening angle between the charged lepton and the @xmath3 quark and the energy of the @xmath3 quark, are also proposed to optimize searches in the chargino channel versus the top channel.
we investigate the radio and @xmath0-ray beaming properties of normal and millisecond pulsars by selecting two samples from the known populations.   the first, sample g, contains pulsars which are detectable in blind searches of @xmath0-ray data from the _ fermi _ large area telescope. the second,   sample r, contains pulsars detectable in blind radio searches which have spin - down luminosities @xmath1  erg s@xmath2.   we analyse the fraction of the @xmath0-ray - selected sample g which have detectable radio pulses and the fraction of the radio - selected sample r which have detectable @xmath0-ray pulses.   twenty of our 35 sample g pulsars have already observed radio pulses.   this rules out low - altitude polar - cap beaming models if, as is currently believed, @xmath0-ray beams are generated in the outer magnetosphere and are very wide.   we further find that, for the highest-@xmath3 pulsars, the radio and @xmath0-ray beams have comparable beaming factors, i.e., the beams cover similar regions of the sky as the star rotates. for lower-@xmath3   @xmath0-ray emitting pulsars, the radio beams have about half of the @xmath0-ray sky coverage.   these results suggest that, for high-@xmath3 young and millisecond pulsars, the radio emission originates in wide beams from regions high in the pulsar magnetosphere, probably close to the null - charge surface and to the @xmath0-ray emitting regions.   furthermore, it suggests that for these high-@xmath4 pulsars, as in the @xmath0-ray case, features in the radio profile represent caustics in the emission beam pattern.
the conditions of local thermodynamic equilibrium of baryons ( non - strange, strange ) and mesons ( strange ) are presented for central au + au collisions at fair energies using the microscopic transport model urqmd. the net particle density, longitudinal - to - transverse pressure anisotropy and inverse slope parameters of the energy spectra of non - strange and strange hadrons are calculated inside a cell in the central region within rapidity window @xmath0 at different time steps after the collision.   we observed that the strangeness content is dominated by baryons at all energies, however contribution from mesons become significant at higher energies. the time scale obtained from local pressure ( momentum ) isotropization and thermalization of energy spectra   are nearly equal and found to decrease with increase in laboratory energy.   the equilibrium thermodynamic properties of the system are obtained with statistical thermal model.   the time evolution of the entropy densities at fair energies are found very similar with the ideal hydrodynamic behaviour at top rhic energy.
wireless sensor networks ( wsns ) with their dynamic applications gained a tremendous attention of researchers.   constant monitoring of critical situations attracted researchers to utilize wsns at vast platforms.   the main focus in wsns is to enhance network life - time as much as one could, for efficient and optimal utilization of resources.   different approaches based upon clustering are proposed for optimum functionality.   network life - time is always related with energy of sensor nodes deployed at remote areas for constant and fault tolerant monitoring. in this work,   we propose quadrature - leach ( q - leach ) for homogenous networks which enhances stability period, network life - time and throughput quiet significantly.   wsns, homogenous ; networks, routing, energy ; efficiency, throughput, network ; life - time.   
we have applied a powerful numerical approach to compute, with a high resolution, the structure of dusty circumstellar disks with embedded planets.   we emphasize some testable implications of our simulations which would verify the presence of a planet via thermal emission of one or more dusty clumps which are in mean motion resonances with the planet.   in particular, our simulations indicate that vega may have a massive planet of @xmath0 ( @xmath1 being jupiter s mass ) at a distance of 5060  au, and epsilon eri may have a less massive planet of @xmath2 at a similar distance of 5565 au.   this conclusion is testable : each resonant feature is stationary in the reference frame co - rotating with the planet, but it is not so for the observer at earth.   therefore, if our interpretation of asymmetric clumps in circumstellar disks as dynamical resonant structures is correct, the above pattern revolves around the star with an angular velocity of @xmath3/yr ( vega ) and @xmath4/yr ( @xmath5  eri )  a prediction that can be tested on a timescale of several years.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
this paper describes the development of a novel algorithm to tackle the problem of real - time video stabilization for unmanned aerial vehicles ( uavs ).   there are two main components in the algorithm : ( 1 ) by designing a suitable model for the global motion of uav, the proposed algorithm avoids the necessity of estimating the most general motion model, projective transformation, and considers simpler motion models, such as rigid transformation and similarity transformation.   ( 2 ) to achieve a high processing speed, optical - flow based tracking is employed in lieu of conventional tracking and matching methods used by state - of - the - art algorithms.   these two new ideas resulted in a real - time stabilization algorithm, developed over two phases.   stage i considers processing the whole sequence of frames in the video while achieving an average processing speed of 50fps on several publicly available benchmark videos.   next, stage ii undertakes the task of real - time video stabilization using a multi - threading implementation of the algorithm designed in stage i.
the effect of the two - nucleon excitation from @xmath0 to @xmath1 shell is discussed in @xmath2c and @xmath3c in the frame work of shell model.   the recently suggested shell - model hamiltonian ysox provides an suitable tool to investigate the @xmath4 excitation in @xmath5 region. because the strength of the @xmath6 interaction, which represents the interaction between the @xmath7 and @xmath4 configurations, is considered in the construction of the ysox   the level of @xmath2c is almost independent on the @xmath6 interaction, but excitation energies of certain states in @xmath3c are strongly affected by it.   further investigation shows that the percentage of @xmath4 configuration in these states is quite different from that of the ground state.    nuclear shell model, @xmath5 model space, hamiltonian ysox, @xmath4 configuration.
this paper presents a practical solution for detecting data races in parallel programs.   the solution consists of a combination of execution replay ( ) with automatic on - the - fly data race detection.   this combination enables us to perform the data race detection on an unaltered execution ( almost no probe effect ).   furthermore, the usage of multilevel bitmaps and snooped matrix clocks limits the amount of memory used. as the record phase of   is highly efficient, there is no need to switch it off, hereby eliminating the possibility of heisenbugs because tracing can be left on all the time.
the properties of distance measures for the quantification of nonclassical properties will be studied.   an ordering of quantum states will be introduced which relies on the basic algebraic definition of classical states.   the classical manipulations of quantum states will be considered to further generalize the ordering.   our order method can be used for a quantification of nonclassicality in a natural way.   we apply this method to introduce a nonclassicality measure, which is based on the fundamental quantum superposition principle.
the paper concerns two interacting consumer - resource pairs based on chemostat - like equations under the assumption that the dynamics of the resource is considerably slower than that of the consumer.   the presence of two different time scales enables to carry out a fairly complete analysis of the problem.   this is done by treating consumers and resources in the coupled system as fast - scale and slow - scale variables respectively and subsequently considering developments in phase planes of these variables, fast and slow, as if they are independent.   when uncoupled, each pair has unique asymptotically stable steady state and no self - sustained oscillatory behavior ( although damped oscillations about the equilibrium are admitted ). when the consumer - resource pairs are weakly coupled through direct reciprocal inhibition of consumers, the whole system exhibits self - sustained relaxation oscillations with a period that can be significantly longer than intrinsic relaxation time of either pair.   it is shown that the model equations adequately describe locally linked consumer - resource systems of quite different nature : living populations under interspecific interference competition and lasers coupled via their cavity losses.
in four space - time dimensions, there are good theoretical reasons for believing that general relativity is the correct geometrical theory of gravity, at least at the classical level. if one admits the possibility of extra space - time dimensions, what would we expect classical gravity to be like?   it is often stated that the most natural generalisation is lovelock s theory, which shares many physical properties with gr.   but there are also key differences and problems.   a potentially serious problem is the breakdown of determinism, which can occur when the matrix of coefficients of second time derivatives of the metric degenerates.   this can be avoided by imposing inequalities on the curvature.   here it is argued that such inequalities occur naturally if the lovelock action is obtained from weyl s formulae for the volume and surface area of a tube.   part of the purpose of this article is to give a treatment of the weyl tube formula in terminology familiar to relativists and to give an appropriate ( straightforward ) generalisation to a tube embedded in minkowski space.   cecs - phy-09/04
we calculate the distribution of the current density @xmath0 in superconducting films along the direction of an external field applied perpendicular to the film plane.   our analysis reveals that in the presence of bulk pinning @xmath0 is inhomogeneous on a length scale of order the inter vortex distance.   this inhomogeneity is significantly enhanced in the presence of surface pinning.   we introduce new critical state model, which takes into account the current density variations throughout the film thickness, and show how these variations give rise to the experimentally observed thickness dependence of @xmath1 and magnetic relaxation rate.
inspired by a class of algorithms proposed by farhi _   et al. _   @xcite, namely the quantum approximate optimization algorithm ( qaoa ), we present a circuit - based quantum algorithm to search for a needle in a haystack, obtaining the same quadratic speedup achieved by grover s original algorithm. in our algorithm, the problem hamiltonian ( oracle ) and a transverse field   are applied alternately to the system in a periodic manner.   we introduced a novel technique, a spin - coherent - state approach, to analyze the composite unitary in a single period.   this composite unitary drives a closed transition between two states that have high degrees of overlap with the initial state and the target state, respectively.   the transition rate in our algorithm is of order @xmath0, and the overlaps are of order @xmath1, yielding a nearly optimal query complexity of @xmath2.   our algorithm is the first example of a qaoa circuit that demonstrates a quantum advantage with large number of iterations that is not derived from trotterization of an adiabatic quantum optimization ( aqo ) algorithm.   it also suggests that the analysis required to understand qaoa circuits involves a very different process from estimating the energy gap of a hamiltonian in aqo.
we present a detailed analysis of a model for the synchronization of nonlinear oscillators due to reactive coupling and nonlinear frequency pulling.   we study the model for the mean field case of all - to - all coupling, deriving results for the initial onset of synchronization as the coupling or nonlinearity increase, and conditions for the existence of the completely synchronized state when all the oscillators evolve with the same frequency.   explicit results are derived for lorentzian, triangular, and top - hat distributions of oscillator frequencies.   numerical simulations are used to construct complete phase diagrams for these distributions.
on the basis of an extensive new spectroscopic survey of galactic o  stars, we introduce the ofc category, which consists of normal spectra with c  iii @xmath0464746504652 emission lines of comparable intensity to those of the of defining lines n  iii @xmath0463446404642.   the former feature is strongly peaked to spectral type o5, at all luminosity classes, but preferentially in some associations or clusters and not others.   the relationships of this phenomenon to the selective c  iii @xmath15696 emission throughout the normal of domain, and to the peculiar, variable of?p category, for which strong c  iii @xmath0464746504652 emission is a defining characteristic, are discussed.   magnetic fields have recently been detected on two members of the latter category.   we also present two new extreme of?p stars, ngc  16242 and cpd  @xmath2  2561, bringing the number known in the galaxy to five.   modeling of the behavior of these spectral features can be expected to better define the physical parameters of both normal and peculiar objects, as well as the atomic physics involved.
in this article we study from a non - perturbative point of view the entanglement of two directed polymers subjected to repulsive interactions given by a dirac @xmath0function potential.   an exact formula of the so - called second moment of the winding angle is derived.   this result is used to provide a thorough analysis of entanglement phenomena in the classical system of two polymers subjected to repulsive interactions and related problems.   no approximation is made in treating the constraint on the winding angle and the repulsive forces.   in particular, we investigate how repulsive forces influence the entanglement degree of the two - polymer system. in the limit of ideal polymers, in which the interactions are switched off,   we show that our results are in agreement with those of previous works.
a continuous stochastic background of gravitational waves ( gws ) for burst sources is produced if the mean time interval between the occurrence of bursts is smaller than the average time duration of a single burst at the emission, i.e., the so called duty cycle must be greater than one. to evaluate the background of gws produced by an ensemble of sources, during their formation, for example, one needs to know the average energy flux emitted during the formation of a single object and the formation rate of such objects as well. in many cases the energy flux emitted during an event of production of gws   is not known in detail, only characteristic values for the dimensionless amplitude and frequencies are known. here   we present a shortcut to calculate stochastic backgrounds of gws produced from cosmological sources. for this approach   it is not necessary to know in detail the energy flux emitted at each frequency.   knowing the characteristic values for the `` lumped '' dimensionless amplitude and frequency we show that it is possible to calculate the stochastic background of gws produced by an ensemble of sources.    2
after close to 20 years of preparation, the dedicated heavy ion experiment alice took first data with proton collisions at the lhc at the end of 2009.   this article recalls the main design choices made for the detector and summarizes initial operation and performance of alice at the lhc ; first physics results are covered elsewhere in these proceedings.
we study the motion of kinks in a two - lane model of the totally asymmetric simple exclusion process with open boundaries.   we analytically study the motion of the kinks by a decoupling approximation. in terms of the decoupling approximation  , we find that the positions of the kinks become synchronised, though the difference in the number of particles between lanes remains non - zero when the rate of lane change is asymmetric.   the validity of this result is confirmed for small asymmetric cases through the monte carlo simulation.
we use the monte carlo generator to predict the cross - sections for double diffractive higgs and di - photon production at the tevatron and lhc. we find that the higgs production cross - section is too small to be observable at tevatron energies, and even at the lhc observation would be difficult.   double diffractive di - photon production, however, should be observable within one year of tevatron run ii.    man / hep/2001/03 + mc - th-01/09 + october 2001    brian cox and jeff forshaw + dept.  of physics and astronomy, university of manchester + manchester m13 9pl, england + coxb@mail.desy.de    beate heinemann + oliver lodge laboratory, university of liverpool + liverpool, l69 7ze, england + beate@fnal.gov
in order to understand the first stages of the nucleation of carbon nanotubes in catalytic processes, we present a tight - binding monte carlo study of the stability and cohesive mechanisms of different carbon structures deposited on nickel ( 100 ) surfaces. depending on the geometry, we obtain contrasted results. on the one hand, the analysis of the local energy distributions of flat carbon sheets, demonstrate that dangling bonds remain unsaturated in spite of the presence of the metallic catalyst.   their adhesion results from the energy gain of the surface ni atoms located below the carbon nanostructure. on the other hand,   carbon caps are stabilized by the presence of carbon atoms occupying the hollow sites of the fcc nickel structure suggesting the saturation of the dangling bonds.
we review models for neutrino mass, with special emphasis in supersymmetric models where r  parity is broken either explicitly or spontaneously.   the simplest unified extension of the ` mssm ` with explicit bilinear r   parity violation provides a predictive scheme for neutrino masses and mixings which can account for the observed atmospheric and solar neutrino anomalies. despite the smallness of neutrino masses r - parity violation   is observable at present and future high - energy colliders, providing an unambiguous cross - check of the model.   this model can be shown to be an effective model for the, more theoretically satisfying, spontaneous broken theory.   the main difference in this last case is the appearance of a massless particle, the majoron, that can modify the decay modes of the higgs boson, making it decay invisibly most of the time.
using a set of zoomed - in cosmological simulations of high - redshift progenitors of massive galaxies, we isolate and trace the history of gas that is accreted by central supermassive black holes.   we determine the origins of the accreted gas, in terms of whether it entered the galaxy during a merger event or was smoothly accreted.   furthermore, we designate whether the smoothly accreted gas is accreted via a cold flow or is shocked upon entry into the halo. for moderate - mass ( @xmath0 m@xmath1 ) black holes at @xmath2, there is a preference to accrete cold flow gas than gas of shocked or merger origin.   however, this result is a consequence of the fact that the entire galaxy has a higher fraction of gas from cold flows. in general  , each black hole tends to accrete the same fractions of smooth- and merger - accreted gas as is contained in its host galaxy, suggesting that once gas enters a halo it becomes well - mixed, and its origins are erased.   we find that the angular momentum of the gas upon halo entry is a more important factor ; black holes preferentially accrete gas that had low angular momentum when it entered the galaxy, regardless of whether it was accreted smoothly or through mergers.
x - ray fluorescent lines are unique features of the reflection spectrum of the torus when irradiated by the central agn. their intrinsic line width can be used to probe the line - emitting region.   previous studies have focused on the fe @xmath0line at 6.4 kev, which is the most prominent fluorescent line.   these studies, however, are limited by the spectral resolution of currently available instruments, the best of which is @xmath1 km  s@xmath2 afforded by the high - energy grating ( heg ). the heg spectral resolution is improved by a factor of 4 at 1.74 kev, where the si @xmath0line is located.   we measured the fwhm of the si @xmath0line for circinus, mrk 3, and ngc 1068, which are @xmath3, @xmath4, and @xmath5 km  s@xmath2, respectively.   they are @xmath6 times smaller than those measured with the fe @xmath0line previously.   it shows that the intrinsic widths of the fe @xmath0line are most likely to be over - estimated.   the measured widths of the si @xmath0line put the line - emitting region outside the dust sublimation radius in these galaxies.   it indicates that for compton - thick agn, the x - ray fluorescence material are likely to be the same as the dusty torus emitting in the infrared.    atomic processes  galaxies : seyfert  galaxies : individual : ( circinus, mrk 3, ngc 1068 )  x - rays : galaxies
this article focuses on the calculation of spectral functions for single- and multi - impurity models using the density matrix renormalization group ( dmrg ). to calculate spectral functions in dmrg,   the correction vector method is presently the most widely used approach.   one, however, always obtains lorentzian convoluted spectral functions, which in applications like the dynamical mean - field theory can lead to wrong results. in order to overcome this restriction,   we use chain decompositions in which the resulting effective hamiltonian can be diagonalized completely to calculate a discrete `` peak '' spectrum.   we show that this peak spectrum is a very good approximation to a deconvolution of the correction vector spectral function.   calculating this deconvoluted spectrum directly from the dmrg basis set and operators is the most natural approach, because it uses only information from the system itself.   having calculated this excitation spectrum, one can use an arbitrary broadening to obtain a smooth spectral function, or directly analyze the excitations. as a nontrivial test   we apply this method to obtain spectral functions for a model of three coupled anderson impurities.   although, we are focusing in this article on impurity models, the proposed method for calculating the peak spectrum can be easily adapted to usual lattice models.
we present three - dimensional hydrodynamic models of radio galaxies interacting with initially relaxed hot atmospheres and explore the significant off - axis radio lobe structures which result under certain conditions. with a focus on the `` winged '' and `` x - shaped '' radio galaxy population, we confirm the importance of observed trends such as the connection of wing formation with jets co - aligned with the major axis of the surrounding atmosphere.   these wings are formed substantially by the deflection of lobe plasma flowing back from the hot spots ( backflow ) and develop in two stages : supersonic expansion of an overpressured cocoon at early times followed by buoyant expansion at later times.   we explore a limited parameter space of jet and atmosphere properties and find that the most prominent wings are produced when a decaying jet is injected into a small, dense, highly elliptical atmosphere. on the basis of this search, we argue that the deflection of backflow by gradients in the hot atmosphere is a strong candidate for forming observed wings but must work in tandem with some other mechanism for forming the initial wing channels.   our models indicate that lobe interaction with the hot atmosphere may play a dominant role in shaping the morphology of radio galaxies.
a graphene antidot lattice, created by a regular perforation of a graphene sheet, can exhibit a considerable band gap required by many electronics devices.   however, deviations from perfect periodicity are always present in real experimental setups and can destroy the band gap.   our numerical simulations, using an efficient linear - scaling quantum transport simulation method implemented on graphics processing units, show that disorder that destroys the band gap can give rise to a transport gap caused by anderson localization.   the size of the defect induced transport gap is found to be proportional to the radius of the antidots and inversely proportional to the square of the lattice periodicity.   furthermore, randomness in the positions of the antidots is found to be more detrimental than randomness in the antidot radius.   the charge carrier mobilities are found to be very small compared to values found in pristine graphene, in accordance with recent experiments.
we present recent star results on photoproduction in ultra - peripheral relativistic heavy ion collisions. in these collisions   the impact parameter of the beam particles is larger than the sum of their nuclear radii, so that they interact via their long - range coulomb fields.   star has measured the production of @xmath0 mesons in exclusive reactions as well as in processes with mutual nuclear excitation of the beam particles.   we present results for the @xmath1  production cross section in @xmath2-@xmath2 collisions at @xmath3  gev for coherent as well as incoherent coupling.   the dependence of the cross section on the @xmath1  rapidity is compared to theoretical models.   we also studied the ratio of coherent  @xmath1  to direct @xmath4@xmath5  production as well as the @xmath1  helicity matrix elements and we observe interference effects in the @xmath1  production. in addition star has measured the production of @xmath1  mesons in @xmath6-@xmath2  collisions at @xmath7  gev and that of @xmath8@xmath9-pairs in @xmath2-@xmath2  at @xmath7  gev.   we also see an enhancement around 1510  @xmath10  in @xmath4@xmath5@xmath4@xmath5  final states in @xmath2-@xmath2  collisions at @xmath3  gev.
we report the discovery of extended radio emission in the phoenix cluster ( spt - cl j23444243, z=0.596 ) with the gmrt at 610  mhz.   the diffuse emission extends over a region of at least 400500  kpc and surrounds the central radio source of the brightest cluster galaxy, but does not appear to be directly associated with it.   we classify the diffuse emission as a radio mini - halo, making it the currently most distant mini - halo known.   radio mini - halos have been explained by synchrotron emitting particles re - accelerated via turbulence, possibly induced by gas sloshing generated from a minor merger event.   chandra observations show a non - concentric x - ray surface brightness distribution, which is consistent with this sloshing interpretation.   the mini - halo has a flux density of @xmath0  mjy, resulting in a 1.4  ghz radio power of @xmath1  w  hz@xmath2. the combined cluster emission, which includes the central compact radio source, is also detected in a shallow gmrt  156  mhz observation and together with the 610  mhz data we compute a spectral index of @xmath3 for the overall cluster radio emission.   given that mini - halos typically have steeper radio spectra than cluster radio galaxies, this spectral index should be taken as an upper limit for the mini - halo.
energy level spectrum of protactinium atom ( pa, @xmath0 ) is simulated with a ci calculation.   levels belonging to the separate manifolds of a given total angular momentum and parity @xmath1 exhibit distinct properties of many - body quantum chaos  . moreover, an extremely strong enhancement of small perturbations takes place. as an example, effective three - electron interaction is investigated and found to play a significant role in the system.   chaotic properties of the eigenstates allow one to develop a statistical theory and predict probabilities of different processes in chaotic systems.
we propose a novel clustering method that is based on physical intuition derived from quantum mechanics. starting with given data points,   we construct a scale - space probability function. viewing the latter as the lowest eigenstate of a schrdinger equation, we use simple analytic operations to derive a potential function whose minima determine cluster centers.   the method has one parameter, determining the scale over which cluster structures are searched.   we demonstrate it on data analyzed in two dimensions ( chosen from the eigenvectors of the correlation matrix ).   the method is applicable in higher dimensions by limiting the evaluation of the schrdinger potential to the locations of data points. in this case   the method may be formulated in terms of distances between data points.
we have made a detailed and quantitative study of dilepton production via bremsstrahlung of a virtual photon during pion - pion collisions.   most calculations of electromagnetic radiation from strong interaction processes rely on the soft photon approximation ( spa ).   the conditions underlying this approximation are generally violated when dilepton spectra are calculated in terms of their invariant mass, so that an approach going beyond the spa becomes necessary.   superseding previous derivations, we derive an exact formula for the bremsstrahlung cross section.   the resulting formulation is compared to various forms based on the spa, the two - particle phase space approximation and rckl s formula using a relativistic one boson exchange ( obe ) model. within the obe approach,   we show that approximations to the bremsstrahlung dilepton cross sections often differ greatly from the exact result ; discrepancies become greater both with rising temperature and with invariant mass.   integrated dilepton production rates are overestimated by rckl - based approximations by factors 1.58.0.   the largest discrepancies occur for the reaction @xmath0, where such approximations overestimate the exact rate by factors ranging from 2 to 30 for invariant masses between 10 and 500 mev.   our findings, combined with recent estimates of the landau - pomeranchuk effect, indicate that bremsstrahlung dileptons rates in ultrarelativistic heavy ion collisions should be even more suppressed than had been thought before.
we present the identification of a bright submillimeter galaxy ( smg ) in the field of abell2218.   the galaxy has a spectroscopic redshift of @xmath04, and is currently the highest redshift smg known.   it is detected at all wavelengths from optical to submm, including the _ spitzer _ irac bands.   we discuss the properties of this galaxy, which is undergoing intense star formation at a rate @xmath0600m@xmath1yr@xmath2.   we also compare the properties to those of radio - preselected submm - bright galaxies.   the @xmath3 result extends the redshift distribution of smgs.
i show the equivalence between a model of financial contagion and the threshold model of global cascades proposed by watts ( 2002 ).   the model financial network comprises banks that hold risky external assets as well as interbank assets.   it is shown that a simple threshold model can replicate the size and the frequency of financial contagion without using information about individual balance sheets.   + keywords : financial network, cascades, financial contagion, systemic risk. + jel codes : g01, g18.
we report a numerical investigation of the fluctuations of the lyapunov exponent of a two dimensional non - interacting disordered system.   while the ratio of the mean to the variance of the lyapunov exponent is not constant, as it is in one dimension, its variation is consistent with the single parameter scaling hypothesis.
mass segregation in a star cluster is studied in an analytical manner.   we consider a two - component cluster, which consists of two types of stars with different masses.   plummer s model is used for the initial condition.   we trace the overall behaviors of the probability distribution functions of the two components and obtain the timescale of mass segregation as a simple function of the cluster parameters.   the result is used to discuss the origin of a black hole with mass of @xmath0 found in the starburst galaxy m82.
cable theory has been developed over the last decades, usually assuming that the extracellular space around membranes is a perfect resistor.   however, extracellular media may display more complex electrical properties due to various phenomena, such as polarization, ionic diffusion or capacitive effects, but their impact on cable properties is not known. in this paper, we generalize cable theory for membranes embedded in arbitrarily complex extracellular media.   we outline the generalized cable equations, then consider specific cases.   the simplest case is a resistive medium, in which case the equations recover the traditional cable equations.   we show that for more complex media, for example in the presence of ionic diffusion, the impact on cable properties such as voltage attenuation can be significant.   we illustrate this numerically always by comparing the generalized cable to the traditional cable.   we conclude that the nature of intracellular and extracellular media may have a strong influence on cable filtering as well as on the passive integrative properties of neurons.
we consider a controlled quantum system whose finite dimensional state is governed by a discrete - time nonlinear markov process. in open - loop,   the measurements are assumed to be quantum non - demolition ( qnd ).   the eigenstates of the measured observable are thus the open - loop stationary states : they are used to construct a closed - loop supermartingale playing the role of a strict control lyapunov function.   the parameters of this supermartingale are calculated by inverting a metzler matrix that characterizes the impact of the control input on the kraus operators defining the markov process.   the resulting state feedback scheme, taking into account a known constant delay, provides the almost sure convergence of the controlled system to the target state.   this convergence is ensured even in the case where the filter equation results from imperfect measurements corrupted by random errors with conditional probabilities given as a left stochastic matrix.   closed - loop simulations corroborated by experimental data illustrate the interest of such nonlinear feedback scheme for the photon box, a cavity quantum electrodynamics system.     ] keywords + + + + + + + +    quantum non - demolition measurements ; measurement - based feedback ; photon - number states ( fock states ) ; quantum filter ; strict control lyapunov function ; markov chain ; feedback stabilization.
we present monte carlo simulations of the reversible transverse susceptibility ( rts ) for a hexagonal array of dipolar interacting magnetic nanoparticles with random anisotropy.   rts curves with the bias - field in - plane and out - of - plane are compared.   with increasing temperature the rts curves evolve from a three - peak ( @xmath0 ) structure to a double - peak and eventually a single - peak at the blocking temperature of the system.   this trend is preserved for weak interactions.   dipolar interactions at low temperature are responsible for the suppression of the @xmath1 peak in the out - of - plane geometry and its progressive merge to the @xmath2 peak with decreasing interparticle separation in the in - plane geometry.   the @xmath2 peaks are located at higher field values in the out - of - plane geometry relative to the in - plane one.   when the bias field lies in - plane ( out - of - plane ) the @xmath2 peaks are shown to shift to lower ( higher ) field values with decreasing interparticle separation. the @xmath1 peak shifts to lower field values in both geometries.   our results are compared with recent experimental findings in self - assembled arrays of fe nanoparticles.
generating nonclassical light offers a benchmark tool for the fundamental research and potential applications in quantum optics.   conventionally, it has become a standard technique to produce the nonclassical light through the nonlinear optical processes occurring in nonlinear crystals. in this review   we describe using cold atomic - gas media to generate such nonclassical light, especially focusing on narrow - band biphoton generation. compared with the standard procedure,   the new biphoton source has such properties as long coherence time, long coherence length, high spectral brightness, and high conversion efficiency. in this paper   we concentrate on the theoretical aspect of the entangled two - photon state produced from the four - wave mixing in a multilevel atomic ensemble.   we show that both linear and nonlinear optical responses to the generated fields play an important role in determining the biphoton waveform and, consequently on the two - photon temporal correlation.   there are two characteristic regimes determined by whether the linear or nonlinear coherence time is dominant.   in addition, our model provides a clear physical picture that brings insight into understanding biphoton optics with this new source.   we apply our model to recent work on generating narrow - band ( and even subnatural linewidth ) paired photons using the technique of electromagnetically induced transparency and slow - light effect in cold atoms, and find good agreements with experimental results.
multiple sclerosis is a degenerative condition of the central nervous system that affects nearly 2.5 million of individuals in terms of their physical, cognitive, psychological and social capabilities.   researchers are currently investigating on the use of patient reported outcome measures for the assessment of impact and evolution of the disease on the life of the patients. to date, a clear understanding on the use of such measures to predict the evolution of the disease is still lacking. in this work we resort to regularized machine learning methods for binary classification and multiple output regression   we propose a pipeline that can be used to predict the disease progression from patient reported measures.   the obtained model is tested on a data set collected from an ongoing clinical research project.
brownian motion of an array of harmonically coupled particles subject to a periodic substrate potential and driven by an external bias is investigated. in the linear response limit ( small bias )  , the coupling between particles may enhance the diffusion process, depending on the competition between the harmonic chain and the substrate potential.   an analytical formula of the diffusion rate for the single - particle case is also obtained. in the nonlinear response regime,   the moving kink may become phase - locked to its radiated phonon waves, hence the mobility of the chain may decrease as one increases the external force.
we covariantize the decoupling limit of massive gravity proposed in @xcite and study the cosmology of this theory as a proxy, which embodies key features of the fully non - linear covariant theory.   we first confirm that it exhibits a self - accelerating solution, similar to what has been found in @xcite, where the hubble parameter corresponds to the graviton mass. for a certain range of parameters fluctuations relative to the self - accelerating background are stable and form an attractor solution.   we also show that a degravitating solution can not be constructed in this covariantized proxy theory in a meaningful way. as for cosmic structure formation  , we find that the helicity-0 mode of the graviton causes an enhancement relative to @xmath0cdm. for consistency   we also compare proxy theories obtained starting from different frames in the decoupling limit and discuss the possibility of obtaining a non - representative proxy theory by choosing the wrong starting frame.   0.9 cm    * cosmology of the galileon from massive gravity *    0.7 cm    claudia de rham and lavinia heisenberg    0.3 cm    _ dpartement de physique thorique and center for astroparticle physics, _    _ universit de genve, 24 quai e. ansermet, ch-1211, genve, switzerland _    1.9 cm
we derive the generalized fokker - planck equation associated with a langevin equation driven by arbitrary additive white noise.   we apply our result to study the distribution of symmetric and asymmetric lvy flights in an infinitely deep potential well.   the fractional fokker - planck equation for lvy flights is derived and solved analytically in the steady state.   it is shown that lvy flights are distributed according to the beta distribution, whose probability density becomes singular at the boundaries of the well.   the origin of the preferred concentration of flying objects near the boundaries in nonequilibrium systems is clarified.
the dav star, hs0507 + 0434b, was observed by fu et al.   ( 2013 ) in 2007 and from 2009 december to 2010 january.   there were a total of six triplets with nearly equal split, which were identified as @xmath0 = 1 modes caused by rotation. in order to fit the six @xmath0 = 1 modes, grids of white dwarf models   are generated by wdec.   for the core composition profiles, we choose the linear fittings to carbon profile of white dwarf models from mesa, which can be considered as results of real nuclear burning process. coupled with diffusion equilibrium h / he and he / c mixtures, we make grids of models in wdec and do asteroseismology works on hs0507 + 0434b.   there is a total of 9.50 seconds error for our best - fitting model, which is smaller than the result ( a total of 22.1 seconds error ) of fu et al.   ( 2013 ), when fitting the six @xmath0 = 1 modes.   the two other previous identified pulsation mode frequencies ( 286.1 s and 743.40 s ) may also be well fitted by our best - fitting model.   the model parameters are @xmath1 = 11450 k, log@xmath2 = 8.088, @xmath3 = 0.640 @xmath4, log(@xmath5/@xmath3 ) = -6, and log(@xmath6/@xmath3 ) = -3.       asteroseismology - stars : individual(hs0507 + 0434b)-white dwarfs
i compute the gluon self - energy in a color superconductor with three flavors of massless quarks, where condensation of cooper pairs breaks the color and flavor @xmath0 symmetry of qcd to the diagonal subgroup @xmath1. at zero temperature,   all eight electric gluons obtain a debye screening mass, and all eight magnetic gluons a meissner mass.   the debye as well as the meissner masses are found to be equal for the different gluon colors.   these masses determine the coefficients of the kinetic terms in the effective theory for the low - energy degrees of freedom.   their values agree with those obtained by son and stephanov.   16.5 cm -1.5 cm    * debye screening and meissner effect in a three - flavor color superconductor * + dirk h.  rischke +   + _ riken - bnl research center _ + _ brookhaven national laboratory, upton, new york 11973, u.s.a. _ + _ email : rischke@bnl.gov_ +   +   +
by employing four typical equation of states ( eoss ) of the inner crust matters, the constraint on properties of low - mass neutron stars are theoretically investigated.   based on the well known fact that there is a big gap between the neutron stars and white dwarfs in the mass - radius sequence of compact stars, here we explicitly point out the forbidden region for the central density and stellar radius to form a compact stars, that is, there is no compact star in the nature having central density in the region from about @xmath0 to @xmath1, and there is also no compact star having a radius in the region from about 400 km to 2000 km. it is found that for a low - mass neutron star with central densities at subnuclear densities, the stellar mass is mainly determined by the softness of the eos at the higher density region ( @xmath2 ) while the stellar radius is dependent on the softness of the eos at lower density region ( @xmath3 ). for a stable neutron star with stellar mass near the minimum mass,   the keplerian period is several hundred millisecond, the moment of inertia is in an order of @xmath4, and the surface gravitational redshift is in an order of @xmath5.
numerical studies of the plane symmetric, vacuum gowdy universe on @xmath0 yield strong support for the conjectured asymptotically velocity term dominated ( avtd ) behavior of its evolution toward the singularity except, perhaps, at isolated spatial points.   a generic solution is characterized by spiky features and apparent `` discontinuities '' in the wave amplitudes.   it is shown that the nonlinear terms in the wave equations drive the system generically to the `` small velocity '' avtd regime and that the spiky features are caused by the absence of these terms at isolated spatial points.    # 1tt@xmath1#1
the milky way can act as a large - scale weak gravitational lens of the cosmic microwave background ( cmb ).   we study this effect using a photon ray - tracing code and a galactic mass distribution with disk, bulge and halo components. for an observer at the sun   s coordinates in the galaxy, the bending of cmb photon paths is limited to less than one arcsecond, and only for rays that pass within a few degrees of the galactic center.   however, the entire sky is affected, resulting in global distortions of the cmb on large angular scales.   these distortions can cause the low - order multipoles of a spherical harmonic expansion of the cmb sky temperature to leak into higher - order modes.   thus the component of the cmb dipole that results from the local group s motion relative to the local cosmic frame of rest contributes to higher - order moments for an observer in the solar system. with our ray - tracing code   we show that the phenomenon is not sensitive to the specific choice of galactic potential.   we also quantitatively rule it out as a contributor to cmb anomalies such as power asymmetry or correlated alignment of low - order multipole moments.
we report the discovery of a tight substellar companion to the young solar analog pz tel, a member of the  pic  moving group observed with high contrast adaptive optics imaging as part of the gemini nici planet - finding campaign.   the companion was detected at a projected separation of 16.4@xmath01.0 au ( 0.33@xmath00.01  ) in april 2009.   second - epoch observations in may 2010 demonstrate that the companion is physically associated and shows significant orbital motion.   monte carlo modeling constrains the orbit of pz tel b to eccentricities @xmath10.6.   the near - ir colors of pz  tel  b indicate a spectral type of m7@xmath02 and thus this object will be a new benchmark companion for studies of ultracool, low - gravity photospheres. adopting an age of 12@xmath2  myr for the system, we estimate a mass of 36@xmath06  based on the lyon / dusty evolutionary models.   pz  tel  b is one of few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system.   additionally, the primary star pz  tel  a shows a 70 @xmath3 m emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion.
the present matter density of the universe, while highly inhomogeneous on small scales, displays approximate homogeneity on large scales.   we propose that whereas it is justified to use the friedmann - lema^ itre - robertson - walker ( flrw ) line element ( which describes an exactly homogeneous and isotropic universe ) as a template to construct luminosity distances in order to compare observations with theory, the _ evolution _ of the scale factor in such a construction must be governed not by the standard einstein equations for the flrw metric, but by the modified friedmann equations derived by buchert @xcite in the context of spatial averaging in cosmology.   furthermore, we argue that this scale factor, defined in the spatially averaged cosmology, will correspond to the effective flrw metric _ provided _ the size of the averaging domain coincides with the scale at which cosmological homogeneity arises.   this allows us, in principle, to compare predictions of a spatially averaged cosmology with observations, in the standard manner, for instance by computing the luminosity distance versus red - shift relation.   the predictions of the spatially averaged cosmology would in general differ from standard flrw cosmology, because the scale - factor now obeys the modified flrw equations.   this could help determine, by comparing with observations, whether or not cosmological inhomogeneities are an alternative explanation for the observed cosmic acceleration.
understanding models which represent the invasion of network - based systems by infectious agents can give important insights into many real - world situations, including the prevention and control of infectious diseases and computer viruses.   here we consider markovian susceptible - infectious - susceptible ( sis ) dynamics on finite strongly connected networks, applicable to several sexually transmitted diseases and computer viruses. in this context, a theoretical definition of endemic prevalence is easily obtained via the quasi - stationary distribution ( qsd ). by representing the model as a percolation process and utilising the property of duality  , we also provide a theoretical definition of invasion probability.   we then show that, for undirected networks, the probability of invasion from any given individual is equal to the ( probabilistic ) endemic prevalence, following successful invasion, at the individual ( we also provide a relationship for the directed case ).   the total ( fractional ) endemic prevalence in the population is thus equal to the average invasion probability ( across all individuals ).   consequently, for such systems, the regions or individuals already supporting a high level of infection are likely to be the source of a successful invasion by another infectious agent.   this could be used to inform targeted interventions when there is a threat from an emerging infectious disease.
we report on the diffusive - ballistic thermal conductance of multi - moded single - crystal silicon beams measured below 1 k. it is shown that the phonon mean - free - path @xmath0 is a strong function of the surface roughness characteristics of the beams.   this effect is enhanced in diffuse beams with lengths much larger than @xmath0, even when the surface is fairly smooth, 5 - 10 nm rms, and the peak thermal wavelength is 0.6 @xmath1 m.   resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm.   hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer.   in contrast, when the beam length is of order @xmath0, the conductance is dominated by ballistic transport and is effectively set by the beam area. we have demonstrated a uniformity of @xmath28% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro - electro - mechanical device and electrical leads.   in addition, we have found no evidence for excess specific heat in single - crystal silicon membranes.   this allows for the precise control of the device heat capacity with normal metal films.   we discuss the results in the context of the design and fabrication of large - format arrays of far - infrared and millimeter wavelength cryogenic detectors.
cygnus x-2 is one of the brightest and longest known x - ray sources.   we present high resolution optical spectroscopy of cygx-2 obtained over 4 years which gives an improved mass function of 0.69 @xmath0 0.03m@xmath1 ( 1@xmath2 ).   in addition, we resolve the rotationally broadened absorption features of the secondary star for the first time, deriving a rotation speed of @xmath3kms@xmath4 ( 1@xmath2 ) which leads to a mass ratio of @xmath5 @xmath0 0.04 ( 1@xmath2, assuming a tidally - locked and roche lobe - filling secondary ).   hence with the lack of x - ray eclipses ( i.e. @xmath6 ) we can set firm 95%  confidence lower limits to the neutron star mass of @xmath7m@xmath1 and to the companion star mass of @xmath8m@xmath1. however, by additionally requiring that the companion must exceed 0.75m@xmath1 ( as required theoretically to produce a steady low - mass x - ray binary ), then @xmath9m@xmath1 and @xmath10 ( 95%  confidence lower and upper limit, respectively ), thereby making cygx-2 the highest mass neutron star measured to date.   if confirmed this would set significant constraints on the equation of state of nuclear matter.
according to dyson s three fold way, from the viewpoint of global time reversal symmetry there are three circular ensembles of unitary random matrices relevant to the study of chaotic spectra in quantum mechanics.   these are the circular orthogonal, unitary and symplectic ensembles, denoted coe, cue and cse respectively. for each of these three ensembles and their thinned versions,   whereby each eigenvalue is deleted independently with probability @xmath0, we take up the problem of calculating the first two terms in the scaled large @xmath1 expansion of the spacing distributions. it is well known that the leading term admits a characterisation in terms of both fredholm determinants and painlev transcendents.   we show that modifications of these characterisations also remain valid for the next to leading term, and that they provide schemes for high precision numerical computations. in the case of the cue   there is an application to the analysis of odlyzko s data set for the riemann zeros, and in that case some further statistics are similarly analysed.
we examine the scaling properties of an evolving network of strings in minkowski spacetime and study the evolution of length scales in terms of a 3-scale model proposed by austin, copeland and kibble ( ack ).   we find good qualitative and some quantitative agreement between the model and our simulations.   we also investigate small - scale structure by altering the minimum allowed size for loop production @xmath0.   certain quantities depend significantly on this parameter : for example the scaling density can vary by a factor of two or more with increasing @xmath0.   small - scale structure as defined by ack disappears if no restrictions are placed on loop production, and the fractal dimension of the string changes smoothly from 2 to 1 as the resolution scale is decreased.   loops are nearly all produced at the lattice cut - off.   we suggest that the lattice cut - off should be interpreted as corresponding to the string width, and that in a real network loops are actually produced with this size.   this leads to a radically different string scenario, with particle production rather than gravitational radiation being the dominant mode of energy dissipation. at the very least, a better understanding of the discretisation effects in all simulations of cosmic strings   is called for.
we propose wave and ray approaches for modelling mid- and high- frequency structural vibrations through smoothed joints on thin shell cylindrical ridges. the models both emerge from a simplified classical shell theory setting.   the ray model is analysed via an appropriate phase - plane analysis, from which the fixed points can be interpreted in terms of the reflection and transmission properties.   the corresponding full wave scattering model is studied using the finite difference method to investigate the scattering properties of an incident plane wave. through both models   we uncover the scattering properties of smoothed joints in the interesting mid - frequency region close to the ring frequency, where there is a qualitative change in the dynamics from anisotropic to simple geodesic propagation.
we revisit the statistical significance of the `` dark flow '' presented in @xcite.   we do not find a statistically significant detection of a bulk flow.   instead we find that cmb correlations between the 8 wmap channels used in this analysis decrease the inferred significance of the detection to 0.7@xmath0.
raman scattering spectra of new fe - based s=2 spin ladder compound bafe@xmath0se@xmath0o are measured in a temperature range between 15 k and 623 k. all six a@xmath1 and two b@xmath1 raman active modes of bafe@xmath0se@xmath0o, predicted by the factor - group analysis, have been experimentally observed at energies that are in a rather good agreement with the lattice dynamics calculation.   the antiferromagnetic long - range spin ordering in bafe@xmath0se@xmath0o below @xmath2=240 k leaves a fingerprint both in the a@xmath1 and b@xmath1 phonon mode linewidth and energy. in the energy range between 400 and 650 @xmath3   we have observed magnetic excitation related structure in the form of magnon continuum, with the peaks corresponding to the singularities in the one dimensional density of magnon states.   the onset value of magnetic continuum ( 2@xmath4 ) is found at about 437 @xmath3 at 15 k. the magnetic continuum disappears at about 623 k, which lead us to conclude that the short - range magnetic ordering in bafe@xmath0se@xmath0o exists apparently up to 2.6@xmath2.
amorphous solids, and many disordered lattices, exhibit a remarkable qualitative and quantitative universality in their acoustic properties at temperature @xmath0k.   this phenomenon is attributed to the existence of tunneling two - level systems ( ttlss ), characterized by a homogenous density of states ( dos ) at energies much lower than the disorder energy ( @xmath1ev ). here   we calculate numerically, from first principles, the dos of kbr : cn glass, the archetypal disordered lattice showing universality.   in contrast to the standard tunneling model, we find that the dos diminishes abruptly at @xmath2k, and that tunneling states differ essentially by their symmetry under inversion.   this structure of the ttlss dictates the low temperature below which universality is observed, and the quantitative universality of the acoustic properties in glasses.   consequences to the properties of glasses at intermediate temperatures, as well as to the microscopic structure of amorphous solids, are discussed.
vastly different time and length scales are a common problem in numerical simulations of astrophysical phenomena. here  , we present an approach to numerical modeling of such objects on the example of type ia supernova simulations.   the evolution towards the explosion proceeds on much longer time scales than the explosion process itself.   the physical length scales relevant in the explosion process cover 11 orders of magnitude and turbulent effects dominate the physical mechanism. despite these challenges, three - dimensional simulations of type ia supernova explosions   have recently become possible and pave the way to a better understanding of these important astrophysical objects.
it is well known that any link can be represented by the closure of a braid.   the minimum number of strings needed in a braid whose closure represents a given link is called the braid index of the link and the well known morton - frank - williams inequality reveals a close relationship between the homfly polynomial of a link and its braid index. in the case that a link is already presented in a closed braid form, jaeger derived a special formulation of the homfly polynomial. in this paper, we prove a variant of jaeger s result as well as a dual version of it. unlike jaeger s original reasoning, which relies on representation theory, our proof uses only elementary geometric and combinatorial observations.   using our variant and its dual version, we provide a direct and elementary proof of the fact that the braid index of a link that has an @xmath0-string closed braid diagram that is also reduced and alternating, is exactly @xmath0. until know this fact was only known as a consequence of a result due to murasugi on fibered links that are star products of elementary torus links and of the fact that alternating braids are fibered.
an approach to a classification of groups generated by 3-state automata over a 2-letter alphabet and the current progress in this direction are presented.   several results related to the whole class are formulated. in particular, all finite, abelian, and free groups are classified.   in addition, we provide detailed information and complete proofs for several groups from the class, with the intention of showing the main methods and techniques used in the classification.
we propose an alternative method to generate samples of a spatially correlated random field with applications to large - scale problems for forward propagation of uncertainty. a classical approach for generating these samples   is the karhunen - love  ( kl ) decomposition.   however, the kl expansion requires solving a dense eigenvalue problem and is therefore computationally infeasible for large - scale problems.   sampling methods based on stochastic partial differential equations provide a highly scalable way to sample gaussian fields, but the resulting parametrization is mesh dependent.   we propose a multilevel decomposition of the stochastic field to allow for scalable, hierarchical sampling based on solving a mixed finite element formulation of a stochastic reaction - diffusion equation with a random, white noise source function.   numerical experiments are presented to demonstrate the scalability of the sampling method as well as numerical results of multilevel monte carlo simulations for a subsurface porous media flow application using the proposed sampling method.   multilevel methods, pdes with random input data, mixed finite elements, uncertainty quantification, multilevel monte carlo    65c05, 60h15, 35r60, 65n30, 65m75, 65c30
we use extensive multi - wavelength photometric data from the great observatories origins deep survey to estimate photometric redshifts for a sample of 434 galaxies with spectroscopic redshifts in the chandra deep field south. using the bayesian method ( bentez 2000 ), which incorporates redshift / magnitude priors, we estimate photometric redshifts for galaxies in the range @xmath0, giving an _ rms _ scatter @xmath1.   the outlier fraction is @xmath2, with the outlier - clipped _   rms _ being 0.047.   we examine the accuracy of photometric redshifts for several, special sub  classes of objects.   the results for extremely red objects are more accurate than those for the sample as a whole, with @xmath3 and very few outliers ( 3% ).   photometric redshifts for active galaxies, identified from their x - ray emission, have a dispersion of @xmath4, with 10% outlier fraction, similar to that for normal galaxies.   employing a redshift / magnitude prior in this process seems to be crucial in improving the agreement between photometric and spectroscopic redshifts.
we study the coherent properties of transmission through kondo impurities, by considering an open aharonov - bohm ring with an embedded quantum dot.   we develop a novel many - body scattering theory which enables us to calculate the conductance through the dot @xmath0, the _ transmission _ phase shift @xmath1, and the normalized visibility @xmath2, in terms of the single - particle @xmath3-matrix. for the single - channel kondo effect, we find at temperatures much below the kondo temperature @xmath4 that @xmath5 without any corrections up to order @xmath6.   the visibility has the form @xmath7.   for the non - fermi liquid fixed point of the two channel kondo, we find that @xmath5 despite the fact that a scattering phase shift is not defined.   the visibility is @xmath8 with @xmath9, thus at zero temperature exactly half of the conductance is carried by single - particle processes, and coherent transmission may actually increase with temperature.   we explain that the spin summation masks the inherent scattering phases of the dot, which can be accessed only via a spin - resolved experiment.   in addition, we calculate the effect of magnetic field and channel anisotropy, and generalize to the k - channel kondo case.
dna adsorption on solid or liquid surfaces is a topic of broad fundamental and applied interest. here   we study by x - ray reflectivity the adsorption of monodisperse double - stranded dna molecules a positively - charged surface, obtained through chemical grafting of a homogeneous organic monomolecular layer of n-(2-aminoethyl ) dodecanamide on an oxide - free monocrystalline si(111 ) wafer. the adsorbed dsdna is found to embed into the soft monolayer which is deformed in the process.   the surface coverage is very high and this adsorbed layer is expected to display 2d nematic ordering.   _ physique de la matire condense, cole polytechnique, cnrs, 91128 palaiseau, france ; institut de recherche interdisciplinaire, cit scientifique, avenue poincar bp 60069, 59652 villeneuve dascq cedex, france ; department of chemistry, university of bath, bath, avon, uk, ba2 7ay ; service de biologie intgrative et de gntique molculaire ; institut de physique thorique, cnrs ura 2306 ; service de physique de ltat condens, cnrs ura 2464, cea / saclay, 91191 gif - sur - yvette cedex, france _   @xmath0to whom correspondance should be addressed.   e - mail : alan.braslau@cea.fr.   + @xmath1physique de la matire condense, cole polytechnique + @xmath2service de biologie intgrative et de gntique molculaire, cea / saclay + @xmath3institut
we define a multiaccess communication scheme that effectively eliminates interference and resolves collisions in many - to - one and many - to - many communication scenarios.   each transmitter is uniquely identified by a steering vector.   all signals issued from a specific transmitter will be steered into the same single - dimensional or double - dimensional subspace at all receivers hearing this transmission.   this subspace is orthogonal to the noise subspace at a receiver and the signals within the subspace can be extracted using the root - music method. at high snr  , local channel knowledge and strict synchronization, the algorithm asymptotically achieves full network capacity on condition that a channel remains constant within a single time slot. without synchronization, the worst case asymptotic performance is still greater than the @xmath0 throughput achieved by collision resolution algorithms and interference management techniques like interference alignment.    _   * index  collision resolution, interference elimination, interference alignment, root - music, steering vectors * _
we describe the coherent manipulation of harmonic oscillator and qubit modes using resonant trains of single flux quantum pulses in place of microwaves.   we show that coherent rotations are obtained for pulse - to - pulse spacing equal to the period of the oscillator.   we consider a protocol for preparing bright and dark harmonic oscillator pointer states.   next we analyze rotations of a two - state qubit system.   we calculate gate errors due to timing jitter of the single flux quantum pulses and due to weak anharmonicity of the qubit.   we show that gate fidelities in excess of 99.9% are achievable for sequence lengths of order 20 ns.
an asymptotic theory is developed for a moving drop driven by a wettability gradient.   we distinguish the mesoscale where an exact solution is known for the properly simplified problem.   this solution is matched at both   the advancing and the receding side  to respective solutions of the problem on the microscale. on the microscale   the velocity of movement is used as the small parameter of an asymptotic expansion.   matching gives the droplet shape, velocity of movement as a function of the imposed wettability gradient and droplet volume.
the silo discharge process is studied by molecular dynamics simulations.   the development of the velocity profile and the probability density function for the displacements in the horizontal and vertical axis are obtained.   the pdfs obtained at the beginning of the discharge reveal non - gaussian statistics and superdiffusive behaviors.   when the stationary flow is developed, the pdfs at shorter temporal scales are non - gaussian too. for big orifices a well defined transition between ballistic and diffusive regime is observed. in the case of a small outlet orifice, no well defined transition is observed.   we use a nonlinear diffusion equation introduced in the framework of non - extensive thermodynamics in order to describe the movements of the grains.   the solution of this equation gives a well defined relationship ( @xmath0 ) between the anomalous diffusion exponent @xmath1 and the entropic parameter @xmath2 introduced by the non - extensive formalism to fit the pdf of the fluctuations.
we study the single transverse - spin asymmetry for dijet production in hadronic collisions in both the collinear qcd factorization approach and the brodsky - hwang - schmidt model.   we show that a nonvanishing asymmetry is generated by both initial - state and final - state interactions, and that the final - state interactions dominate.   we find that in the leading kinematic region where the transverse momentum imbalance of the two jets, @xmath0, is much less than the momentum of either jet, the contribution from the lowest non - trivial perturbative order to both the spin - averaged and the spin - dependent dijet cross sections can be factorized into a hard part that is a function only of the averaged jet momentum @xmath1, and perturbatively generated transverse momentum dependent ( tmd ) parton distributions.   we show that the spin asymmetry at this non - trivial perturbative order can be described by the tmd parton distributions defined in either semi - inclusive dis or the drell - yan process.   we derive the same hard parts from both the collinear factorization approach and in the context of the brodsky - hwang - schmidt model, verifying that they are not sensitive to details of the factorized long distance physics.
we determine the character of orbits of stars moving in the meridional plane @xmath0 of an axially symmetric time - independent disk galaxy model with a spherical central nucleus.   in particular, we try to reveal the influence of the value of the angular momentum on the different families of orbits of stars, by monitoring how the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families evolve when angular momentum varies.   the smaller alignment index ( sali ) was computed by numerically integrating the equations of motion as well as the variational equations to extensive samples of orbits in order to distinguish safely between ordered and chaotic motion.   in addition, a method based on the concept of spectral dynamics that utilizes the fourier transform of the time series of each coordinate is used to identify the various families of regular orbits and also to recognize the secondary resonances that bifurcate from them.   our investigation takes place both in the physical @xmath0 and the phase @xmath1 space for a better understanding of the orbital properties of the system.   our numerical computations reveal that low angular momentum stars are most likely to move in chaotic orbits, while on the other hand, the vast majority of high angular momentum stars perform regular orbits.   galaxies : kinematics and dynamics  galaxies : structure, chaos
the broad - band variability of many accreting systems displays characteristic structure ; log - normal flux distributions, rms - flux relations, and long inter - band lags.   these characteristics are usually interpreted as inward propagating fluctuations in an accretion disk driven by stochasticity of the angular momentum transport mechanism.   we present the first analysis of propagating fluctuations in a long - duration, high - resolution, global three - dimensional magnetohydrodynamic ( mhd ) simulation of a geometrically - thin ( @xmath0 ) accretion disk around a black hole. while the dynamical - timescale turbulent fluctuations in the maxwell stresses are too rapid to drive radially - coherent fluctuations in the accretion rate  , we find that the low - frequency quasi - periodic dynamo action introduces low - frequency fluctuations in the maxwell stresses which then drive the propagating fluctuations.   examining both the mass accretion rate and emission proxies, we recover log - normality, linear rms - flux relations, and radial coherence that would produce inter - band lags.   hence, we successful relate and connect the phenomenology of propagating fluctuations to modern mhd accretion disk theory.
in this talk i will present a model for primordial galaxy formation.   in particular, i will review the feedback effects that regulate the process : ( i ) radiative ( i.e. ionizing and h@xmath0photodissociating photons ) and ( ii ) stellar ( i.e. sn explosions ) feedback produced by massive stars.   i will show the results of a model for galaxy formation and igm reionization, which includes a self - consistent treatment of the above feedback effects.   finally, i will describe a monte carlo method for the radiative transfer of ionizing photons through the igm and discuss its application to the igm reionization problem.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present radiative one - loop neutrino mass model with hypercharge zero scalar triplet in conjunction with another charged singlet scalar and an additional vectorlike lepton doublet.   we study three variants of this mass model : the first one without additional beyond - sm symmetry, the second with imposed dm - stabilizing discrete @xmath0 symmetry, and the third in which this @xmath0 symmetry is promoted to the gauge symmetry @xmath1.   the two latter cases are scotogenic, with a neutral component of the scalar triplet as a dark matter candidate. in first scotogenic model   the @xmath0-odd dark matter candidate is at the multi - tev mass scale, so that all new degrees of freedom are beyond the direct reach of the lhc. in second scotogenic setup, with   broken @xmath1 symmetry the model may have lhc signatures or be relevant to astrophysical observations, depending on the scale of @xmath1 breaking.   ztf - ep-13 - 04 +    * radiative neutrino mass + with scotogenic scalar triplet + *     +    _ pacs _ : 14.60.pq ; 95.35.+d + _ keywords _ : neutrino mass ; dark matter
necessary and sufficient conditions for deterministic remote extraction and destruction of qubit information encoded in bipartite states using only local operations and classical communications ( locc ) are presented.   the conditions indicate that there is a way to asymmetrically spread qubit information between two parties such that it can be remotely extracted with unit probability at one of the parties but not at the other as long as they are using locc.   remote destruction can also be asymmetric between the two parties, but the conditions are incompatible with those for remote extraction.
we consider the problem of a single level quantum dot coupled to the edge of a one - dimensional luttinger liquid wire by both a hopping term and electron - electron interactions.   using bosonization and coulomb gas mapping of the anderson - yuval type we show that thermodynamic properties of the level, in particular, its occupation, depend on the various interactions in the system only through a single quantity  the corresponding fermi edge singularity exponent.   however, dynamical properties, such as the level density of states, depend in a different way on each type of interaction.   hence, we can construct different models, with and without interactions in the wire, with equal fermi edge singularity exponents, which have identical population curves, although they originate from very different level densities of states.   the latter may either be regular or show a power - law suppression or enhancement at the fermi energy.   these predictions are verified to a high degree of accuracy using the density matrix renormalization group algorithm to calculate the dot occupation, and classical monte carlo simulations on the corresponding coulomb gas model to extract the level density of states.   ,  ,    luttinger liquid, quantum dots, impurity levels, coulomb gas 71.10.pm, 73.20.hb, 73.21.hb, 73.21.la
in this paper we study multivariate polynomial functions in complex variables and their corresponding symmetric tensor representations. the focus is to find conditions under which such complex polynomials always take real values.   we introduce the notion of symmetric conjugate forms and general conjugate forms, characterize the conditions for such complex polynomials to be real - valued, and present their corresponding tensor representations.   new notions of eigenvalues / eigenvectors for complex tensors are introduced, extending similar properties from the hermitian matrices.   moreover, we study a property of the symmetric tensors, namely the largest eigenvalue ( in the absolute value sense ) of a symmetric real tensor is equal to its largest singular value ; the result is also known as banach s theorem.   we show that a similar result holds for the complex case as well. finally, we discuss some applications of the new notion of eigenvalues / eigenvectors for the complex tensors.   * keywords : * symmetric complex tensor ; conjugate complex polynomial ; tensor eigenvalue ; tensor eigenvector ; nonnegative polynomial.   * mathematics subject classification : * 15a69, 15a18, 15b57, 15b48.
we consider utility maximization in networks where the sources do not employ flow control and may consequently overload the network. in the absence of flow control at the sources, some packets will inevitably have to be dropped when the network is in overload. to that end, we first develop a distributed, threshold - based packet dropping policy that maximizes the weighted sum throughput.   next, we consider utility maximization and develop a receiver - based flow control scheme that, when combined with threshold - based packet dropping, achieves the optimal utility.   the flow control scheme creates virtual queues at the receivers as a _ push - back _ mechanism to optimize the amount of data delivered to the destinations via back - pressure routing.   a novel feature of our scheme is that a utility function can be assigned to a collection of flows, generalizing the traditional approach of optimizing per - flow utilities.   our control policies use finite - buffer queues and are independent of arrival statistics.   their near - optimal performance is proved and further supported by simulation results.
as one of the recently proposed algorithms for sparse system identification, @xmath0 norm constraint least mean square ( @xmath0-lms ) algorithm modifies the cost function of the traditional method with a penalty of tap - weight sparsity.   the performance of @xmath0-lms is quite attractive compared with its various precursors.   however, there has been no detailed study of its performance.   this paper presents comprehensive theoretical performance analysis of @xmath0-lms for white gaussian input data based on some assumptions which are reasonable in a large range of parameter setting.   expressions for steady - state mean square deviation ( msd ) are derived and discussed with respect to algorithm parameters and system sparsity.   the parameter selection rule is established for achieving the best performance.   approximated with taylor series, the instantaneous behavior is also derived.   in addition, the relationship between @xmath0-lms and some previous arts and the sufficient conditions for @xmath0-lms to accelerate convergence are set up. finally,   all of the theoretical results are compared with simulations and are shown to agree well in a wide range of parameters.   * keywords : * adaptive filter, sparse system identification, @xmath0-lms, mean square deviation, convergence rate, steady - state misalignment, independence assumption, white gaussian signal, performance analysis.
we searched for eclipses of two millisecond pulsars, psr j1807@xmath02459 and psr b1908 + 00.   these pulsars are in very low mass binary systems with orbital parameters similar to those of eclipsing binaries.   observations were made with the gbt at frequencies as low as 575mhz.   no eclipses were detected in either system.   observations of well - established eclipsing binary j2051@xmath00827 found eclipses to be substantially weaker than previously seen, with the pulsar detected throughout the eclipse region at 575mhz and with an electron column density an order of magnitude smaller than previously measured.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
protoplanetary disks are composed primarily of gas ( 99% of the mass ). nevertheless, relatively few observational constraints exist for the gas in disks. in this review,   i discuss several observational diagnostics in the uv, optical, near - ir, mid - ir, and ( sub)-mm wavelengths that have been employed to study the gas in the disks of young stellar objects.   i concentrate in diagnostics that probe the inner 20 au of the disk, the region where planets are expected to form.   i discuss the potential and limitations of each gas tracer and present prospects for future research.
we present radio transient search algorithms, results, and statistics from the ongoing arecibo pulsar alfa ( palfa ) survey of the galactic plane.   we have discovered seven objects through a search for isolated dispersed pulses.   all of these objects are galactic and have measured periods between 0.4 and 4.7  s. one of the new discoveries has a duty cycle of 0.01%, smaller than that of any other radio pulsar.   we discuss the impact of selection effects on the detectability and classification of intermittent sources, and compare the efficiencies of periodicity and single - pulse searches for various pulsar classes. for some cases   we find that the apparent intermittency is likely to be caused by off - axis detection or a short time window that selects only a few bright pulses and favors detection with our single - pulse algorithm.   in other cases, the intermittency appears to be intrinsic to the source.   no transients were found with dispersion measures large enough to require that they originate from sources outside our galaxy.   accounting for the on - axis gain of the alfa system, as well as the low gain but large solid - angle coverage of far - out sidelobes, we use the results of the survey so far to place limits on the amplitudes and event rates of transients of arbitary origin.
in this paper we penetrate and extend the notion of local constancy in graphical models that has been introduced by honorio et al.   ( 2009 ).   we propose _ neighborhood - fused lasso _, a method for model selection in high - dimensional graphical models, leveraging locality information.   our approach is based on an extension of the idea of node - wise regression ( meinshausen - bhlmann, 2006 ) by adding a fusion penalty.   we propose a fast numerical algorithm for our approach, and provide theoretical and numerical evidence for the fact that our methodology outperforms related approaches that are ignoring the locality information.   we further investigate the compatibility issues in our proposed methodology and derive bound for the quadratic prediction error and @xmath0-bounds on the estimated coefficients.
the discovery of high-@xmath0 superconductivity in the pnictides, materials with a fermi surface determined by several bands, highlights the need to understand how superconductivity arises in multiband systems. in this effort, using symmetry considerations and mean - field approximations, we discuss how strong hybridization among orbitals may lead to both intra and interband pairing, and we present calculations of the spectral functions to guide the experimental search for this kind of state.
electric current and spacial displacement due to trembling motion  of electrons in graphene in the presence of an external magnetic field are described.   contributions of both inequivalent @xmath0 points in the brillouin zone of graphene are considered.   it is shown that, when the electrons are prepared in the form of wave packets, the presence of a quantizing magnetic field @xmath1 has very important effects on zb.   ( 1 ) for @xmath2 the zb oscillations are permanent, for @xmath3 they are transient. ( 2 ) for @xmath2 many zb frequencies appear, for @xmath3 only one frequency is at work. ( 3 ) for @xmath2 both interband and intraband ( cyclotron ) frequencies contribute to zb, for @xmath3 there are no intraband frequencies.   ( 4 ) magnetic field intensity changes not only the zb frequencies but the entire character of zb spectrum.   an emission of electromagnetic dipole radiation by the trembling electrons is proposed and described.   it is argued that graphene in a magnetic field is a promising system for an experimental observation of zitterbewegung.
we study the geodesic motion of massive and massless test particles in the background of a particular class of multiple charge black holes in gauged supergravity theories in @xmath0.   we have analysed the horizon structure along with the nature of the effective potentials for the case of four equal charges. in view of the corresponding effective potentials,   we have discussed all the possible orbits in detail for different values of energy and angular momentum of the incoming test particles.   the periods for one complete revolution of circular orbits and the advance of perihelion of the planetary orbit have also been investigated in greater detail for massive test particles.   we have also discussed the time period of unstable circular motion and cone of avoidance of massless test particles in detail.   all the corresponding results obtained for massive and massless test particles are then compared accordingly.
we show that the  practical " bell inequalities, which use intensities as the observed variables, commonly used in quantum optics and widely accepted in the community, suffer from an inherent loophole, which severely limits the range of local hidden variable theories of light, which are invalidated by their violation  . we present alternative inequalities which do not suffer from any ( theoretical ) loophole.   the new inequalities use redefined correlation functions, which involve averaged products of local rates rather than intensities.   surprisingly, the new inequalities detect entanglement in situations in which the  practical " ones fail. thus, we have two for the price on one : full consistency with bell s theorem, and better device - independent detection of entanglement.
* we present the micro - photoluminescence ( ) and micro - reflectance contrast ( ) spectroscopy studies on thin films of 2 with layer thicknesses ranging from a monolayer ( 1l ) up to 5l.   the thickness dependent evolution of the ground and excited state excitonic transitions taking place at various points of the brillouin zone is determined.   temperature activated energy shifts and linewidth broadenings of the excitonic resonances in 1l, 2l and 3l flakes are accounted for by using standard formalisms previously developed for semiconductors.   a peculiar shape of the optical response of the ground state ( a ) exciton in monolayer 2 is tentatively attributed to the appearance of fano - type resonance. rather trivial and clearly decaying   pl spectra of monolayer 2 with temperature confirm that the ground state exciton in this material is optically bright in contrast to a dark exciton ground state in monolayer 2. *
we consider radion stabilization in hyperbolic brane - world scenarios.   we demonstrate that in the context of einstein gravity, matter fields which stabilize the extra dimensions must violate the null energy condition.   this result is shown to hold even allowing for frw - like expansion on the brane.   in particular, we explicitly demonstrate how one putative source of stabilizing matter fails to work, and how others violate the above condition.   we speculate on a number of ways in which we may bypass this result, including the effect of casimir energy in these spaces. a brief discussion of supersymmetry in these backgrounds is also given.
grover s search algorithm is the optimal quantum algorithm that can search an unstructured database quadratically faster than any known classical algorithm.   the role of entanglement and correlations in the search algorithm have been studied in great detail and it is known that entanglement between the qubits is necessary to gain a quadratic speedup, for pure state implementation of the grover search algorithm. here, we systematically investigate the behavior of quantum coherence and monogamy of entanglement in the discrete analogue of the _ analog analogue of grover search algorithm_. the analog analogue of grover search is a continuous time quantum algorithm based on the adiabatic hamiltonian evolution that gives a quadratic speedup, similar to the original grover search algorithm.   we show that the decrease of quantum coherence, quantified using various coherence monotones, is a clear signature of attaining the maximum success probability in the analog grover search.   we also show that for any two qubit reduced density matrix of the system, the concurrence evolves in close vicinity to the increasing rate of success probability.   furthermore, we show that the system satisfies a @xmath0-party monogamy inequality for arbitrary times, hence bounding the amount of @xmath0-qubit entanglement during the quantum search.
we present _ chandra _ observations of two nearby radio galaxies in group environments, 3c285 and 3c442a.   the host galaxies of both sources are involved in mergers with nearby massive galaxies, and the hot gas in the systems is extended along lines joining the interacting galaxies.   both sources show strong evidence for interactions between the radio lobes and the asymmetrical hot gas.   we argue that the structure in the hot gas is independent of the existence of the radio lobes in these systems, and argue that hot gas shaped by an ongoing massive galaxy merger may play an important role in the dynamics of radio lobes in other objects. for 3c442a,   our observations show that gas is being driven out of both members of the host interacting galaxy pair, and the implied constraints on galaxy velocities are consistent with mildly supersonic motions with respect to the group - scale hot gas.   the previously known filamentary radio structure in the center of 3c442a may be a result of the interaction between hot gas expelled from these galaxies and pre - existing radio - emitting plasma. in 3c285, where there is no ongoing galaxy merger  , the powerful radio source is probably having a significant effect on the energetics of the host group.
in this paper, we present a reduced basis method for pricing european and american options based on the black - scholes and heston model. to tackle each model numerically,   we formulate the problem in terms of a time dependent variational equality or inequality.   we apply a suitable reduced basis approach for both types of options.   the characteristic ingredients used in the method are a combined pod - greedy and angle - greedy procedure for the construction of the primal and dual reduced spaces. analytically, we prove the reproduction property of the reduced scheme and derive a posteriori error estimators.   numerical examples are provided, illustrating the approximation quality and convergence of our approach for the different option pricing models.   also, we investigate the reliability and effectivity of the error estimators.
the correlation is one of the most intriguing and debated observational evidences in gamma- ray bursts ( grb ) astrophysics.  , with its high sensitivity and fast pointing capabilities, is reducing a lot the impact of selection effects in the sample of grbs with known redshift ( and thus and ).   moreover, in several cases it allows the detection of the soft tail of the prompt emission, and thus a more accurate estimate of with respect to previous satellites.   i present and discuss the location in the plane of grbs with known redshift and estimated, showing that all long events ( inlcuding peculiar events like grb060218 and grb060614 ) are consistent with the correlation. in contrast, short grbs are not consistent with it, an evidence further supporting the hypothesis of different emission mechanisms at work in the two classes of grbs.   i also show, and briefly discuss, the intriguing evidence that the soft tail of the short grb050724 is consistent with the correlation.   
we present a statistical analysis that demonstrates that the overwhelming majority of _ kepler  _ candidate multiple transiting systems ( multis ) indeed represent true, physically - associated transiting planets.   binary stars provide the primary source of false positives among _ kepler  _ planet candidates, implying that false positives should be nearly randomly - distributed among _   kepler  _ targets.   in contrast, true transiting planets would appear clustered around a smaller number of _ kepler  _ targets if detectable planets tend to come in systems and/or if the orbital planes of planets encircling the same star are correlated.   there are more than one hundred times as many _   kepler  _ planet candidates in multi - candidate systems as would be predicted from a random distribution of candidates, implying that the vast majority are true planets.   most of these multis are multiple planet systems orbiting the _ kepler  _ target star, but there are likely cases where ( a ) the planetary system orbits a fainter star, and the planets are thus significantly larger than has been estimated, or ( b ) the planets orbit different stars within a binary / multiple star system.   we use the low overall false positive rate among _   kepler  _ multis, together with analysis of _ kepler  _ spacecraft and ground - based data, to validate the closely - packed kepler-33 planetary system, which orbits a star that has evolved somewhat off of the main sequence.   kepler-33 hosts five transiting planets with periods ranging from 5.67 to 41 days.
personal sensory data is used by context - aware mobile applications to provide utility.   however, the same data can be used by an adversary to make sensitive inferences about a user thereby violating her privacy.   we present deeprotect, a framework that enables a novel form of access control that we refer to as the _ inference - based access control _  , in which mobile apps with access to sensor data are limited ( provably ) in their ability to make inferences about user s sensitive data and behavior.   deeprotect adopts a two - layered privacy strategy.   first, it leverages novel deep learning techniques to perform data minimization and limits the amount of information being shared ; the learning network is used to derive a compact representation of sensor data consisting only of features relevant to authorized utility - providing inferences.   second, deeprotect obfuscates the previously learnt features, thereby providing an additional layer of protection against sensitive inferences ; our approach can provide both conventional and relaxed notions of local differential privacy, depending on how sensitive inferences are specified. through theoretical analysis and extensive experiments using real - world apps and datasets,   we demonstrate that when compared to existing approaches deeprotect provides provable privacy guarantees with up to @xmath0 improvement in utility. finally, deeprotect shares obfuscated but raw sensor data reconstructed from the perturbed features, thus requiring no changes to the existing app interfaces.
making use of a generalized quantum theory of paraxial light propagation where the radiation - axis and the temporal coordinates play exchanged roles, we discuss the potential of bulk nonlinear optical media in cavityless configurations for quantum statistical mechanics studies of the conservative many - body dynamics of a gas of interacting photons.   to illustrate the general features of this point of view, we investigate the response of the fluid of light to the quantum quenches in the photon - photon interaction constant experienced at the front and the back faces of a finite slab of weakly nonlinear material. extending the standard bogoliubov theory of   dilute bose - einstein condensates, peculiar features are predicted for the statistical properties of the light emerging from the nonlinear medium.
this paper describes an artificial embryology method ( called `` epigenetic tracking '' ) to generate predefined arbitrarily shaped 2-dimensional arrays of cells by means of evolutionary techniques.   it is based on a model of development, whose key features are : i ) the distinction bewteen `` normal '' and `` driver '' cells, being the latter able to receive guidance from the genome, ii ) the implementation of the proliferation / apoptosis events in such a way that many cells are created / deleted at once, in order to speed - up the morphogenetic process.   iii ) the presence in driver cells of an epigenetic memory, that holds the position of the cell in the cell lineage tree and represents the source of differentiation during development.   the experiments performed with a number of 100x100 black and white and colour target shapes ( the horse, the couple, the hand, the dolphin, the map of britain, the foot, the frog, the baby, the stomach, the french flag, the head ) bring to the conclusion that the method described is able to generate any target shape, outperforming any other known method in terms of size and variety of the generated shapes.   the interpretation of the proposed method as a model of embryogenesis and its biological implications are discussed.
low - density parity - check ( ldpc ) convolutional codes are capable of achieving excellent performance with low encoding and decoding complexity. in this paper   we discuss several graph - cover - based methods for deriving families of time - invariant and time - varying ldpc convolutional codes from ldpc block codes and show how earlier proposed ldpc convolutional code constructions can be presented within this framework.    some of the constructed convolutional codes significantly outperform the underlying ldpc block codes.   we investigate some possible reasons for this `` convolutional gain, '' and we also discuss the  mostly moderate  decoder cost increase that is incurred by going from ldpc block to ldpc convolutional codes.   pusane, smarandache, vontobel, costello    block codes, convolutional codes, low - density parity - check ( ldpc ) codes, message - passing iterative decoding, pseudo - codewords, pseudo - weights, quasi - cyclic codes, unwrapping, wrapping.
we study dynamics of equation of state parameter for a non - minimally coupled quintom dark energy component on the warped dgp brane.   we investigate crossing of the cosmological constant line in this scenario.   this crossing occurs in both dgp@xmath0 branches of the model. + * pacs * : 04.50.-h, 11.25.wx, 95.36.+x, 98.80.-k + * key words * : dark energy models, braneworld scenarios    0 mm 0 mm 0 mm 0 mm 0 mm 160 mm 210 mm.65 cm     +,, and + @xmath1_department of physics, faculty of basic sciences, + university of mazandaran, + p. o. box 47416 - 95447, babolsar, iran _   + @xmath2 _ department of science, payam - e nour university, bijar, iran _ + _ @xmath3 department of physics, payam - e nour university, + p. o. box 919, mashad, iran _
we report on the discovery of an infrared cometary nebula around psr j1549@xmath04848 in our spitzer survey of a few middle - aged radio pulsars. following the discovery,   multi - wavelength imaging and spectroscopic observations of the nebula were carried out.   we detected the nebula in spitzer irac 8.0, mips 24 and 70 @xmath1 m imaging and in spitzer irs 7.514.4 @xmath1 m spectroscopic observations, and also in the wise all - sky survey at 12 and 22 @xmath1 m. these data were analyzed in detail, and we find that the nebula can be described with a standard bow - shock shape, and that its spectrum contains polycyclic aromatic hydrocarbon and h@xmath2 emission features.   however, it is not certain which object drives the nebula.   we analyze the field stars and conclude that none of them can be the associated object because stars with a strong wind or mass ejection that usually produce bow shocks are much brighter than the field stars.   the pulsar is approximately 15  away from the region in which the associated object is expected to be located. in order to resolve the discrepancy  , we suggest that a highly collimated wind could be emitted from the pulsar and produce the bow shock.   x - ray imaging to detect the interaction of the wind with the ambient medium and high - spatial resolution radio imaging to determine the proper motion of the pulsar should be carried out, which will help verify the association of the pulsar with the bow shock nebula.
in this paper we review some results on time - homogeneous birth - death processes. specifically, for truncated birth - death processes with two absorbing or two reflecting endpoints  , we recall the necessary and sufficient conditions on the transition rates such that the transition probabilities satisfy a spatial symmetry relation.   the latter leads to simple expressions for first - passage - time densities and avoiding transition probabilities.   this approach is thus thoroughly extended to the case of bilateral birth - death processes, even in the presence of catastrophes, and to the case of a two - dimensional birth - death process with constant rates. + _ keywords : _ truncated processes ; bilateral processes ; transition probabilities ; spatial symmetry ; absorption ; reflection ; first - passage time ; avoiding transition probabilities ; catastrophes.   + _ mathematical subject classification : _ 60j80
the time - of - flight ( tof ) system of the ams detector gives the fast trigger to the read out electronics and measures velocity, direction and charge of the crossing particles.   the first version of the detector ( called ams-01 ) has flown in 1998 aboard of the shuttle discovery for a 10 days test mission, and collected about @xmath0 events. the new version ( called ams-02 )   will be installed on the international space station and will operate for at least three years, collecting roughly @xmath1 cosmic ray ( cr ) particles.   the tof system of ams-01 successfully operated during the test mission, obtaining a time resolution of 120 ps for protons and better for other cr ions.   the tof system of ams-02 will be different due to the strong fringing magnetic field and weight constraints.   [ _ talk given at the `` first international conference on particle and fundamental physics in space '', la biodola, isola delba ( italy ), 14  19 may 2002. to be published by nuclear physics b - proceedings supplement.   _ ]
we consider a hubble expansion law modified in the infra - red by distance - dependent terms, and attempt to enforce homogeneity upon it. as a warm - up  , we re - derive the basic kinematics of a friedman robertson walker universe without using standard general relativistic tools : we describe the expansion with a ` hubble velocity field'rather than with a four dimensional metric  . then we extend this analysis to the modified hubble expansion and impose a transformation for velocities that makes it identical for all comoving observers, and therefore homogeneous.   we derive the modified equation for light ray trajectories and other geometrical properties that are incompatible with the general relativistic description.   we speculate that this extended framework could help addressing cosmological problems which are normally explained with accelerating expansions.
strangeness production is calculated in a pqcd - based model ( including nuclear effects ) in the high transverse momentum sector, where pqcd is expected to work well.   we investigate pion, kaon, proton and lambda production in @xmath0 and heavy - ion collisions.   parton energy loss in @xmath1 collisions is taken into account.   we compare strange - to - non - strange meson and baryon ratios to data at rhic, and make predictions for the lhc.   we find that these ratios significantly deviate from unity not only at rhic but also at the lhc, indicating the special role of strangeness at both energies.
we investigate how well the one - dimensional hubbard model describes the entanglement of particles trapped in a string of quantum wells.   we calculate the average single - site entanglement for two particles interacting via a contact interaction and consider the effect of varying the interaction strength and the interwell distance.   we compare the results with the ones obtained within the one - dimensional hubbard model with on - site interaction.   we suggest an upper bound for the average single - site entanglement for two electrons in @xmath0 wells and discuss analytical limits for very large repulsive and attractive interactions.   we investigate how the interplay between interaction and potential shape in the quantum well system dictates the position and size of the entanglement maxima and the agreement with the theoretical limits.   finally we calculate the spatial entanglement for the quantum well system and compare it to its average single - site entanglement.
in this paper we study the effect of finite size on the two - flavour colour superconducting state. as well as restricting the quarks to a box, we project onto states of good baryon number and onto colour singlets, these being necessary restrictions on any observable `` quark nuggets ''. we find that whereas finite size alone has a significant effect for very small boxes, with the superconducting state often being destroyed, the effect of projection is to restore it again.   the infinite - volume limit is a good approximation even for quite small systems.
we perform a likelihood analysis of the recently released boomerang and maxima data, allowing for the possibility of a time - varying fine - structure constant.   we find that in general this data prefers a value of @xmath0 that was smaller in the past ( which is in agreement with measurements of @xmath0 from quasar observations ).   however, there are some interesting degeneracies in the problem which imply that strong statements about @xmath0 can not be made using this method until independent accurate determinations of @xmath1 and @xmath2 are available.   we also show that a preferred lower value of @xmath0 comes mainly from the data points around the first doppler peak, whereas the main effect of the high-@xmath3 data points is to increase the preferred value for @xmath1 ( while also tightening the constraints on @xmath4 and @xmath2 ).   we comment on some implications of our results.
the first polarimetric images of the omc-3 region of the orion a filamentary molecular cloud are presented. using the new imaging polarimeter on scuba at the james clerk maxwell telescope,   we have detected polarized thermal emission at 850  from dust along a 6  length of the dense filament.   the polarization pattern is highly ordered and is aligned with the long axis of the filament throughout most of the region, diverging only near the southern boundary by @xmath0@xmath1. if the polarization arises from thermal emission of dust grains aligned via either paramagnetic inclusions or radiative torques, this configuration indicates a plane - of - sky magnetic field which is normal to the filament along most of its length.   the mean percentage polarization is 4.2% with a 1@xmath2 dispersion of 1%.   this region is part of the integral - shaped filament, and active star formation is ongoing along its length, with only two of nine dust condensations in our field lacking evidence of outflow activity.   the outflow directions do not appear to be consistently correlated with the direction of the plane - of - sky field or the filament structure itself.   depolarization toward the filament center, previously detected in many other star - forming cores and protostars, is also evident in our data.
we present agn__fitter _ _ : a markov chain monte carlo algorithm developed to fit the spectral energy distributions ( seds ) of active galactic nuclei ( agn ) with different physical models of agn components.   this code is well suited to determine in a robust way multiple parameters and their uncertainties, which quantify the physical processes responsible for the panchromatic nature of active galaxies and quasars.   we describe the technicalities of the code and test its capabilities in the context of x - ray selected obscured agn using multiwavelength data from the xmm - cosmos survey.
the electronic properties of the novel two dimensional ( 2d ) material silicene are strongly influenced by the application of a perpendicular electric field @xmath0 and of an exchange field @xmath1 due to adatoms positioned on the surface or a ferromagnetic substrate. within the random phase approximation, we investigate how electron - electron interactions are affected by these fields and present analytical and numerical results for the dispersion of plasmons, their lifetime, and their oscillator strength.   we find that the combination of the fields @xmath0 and @xmath1 brings a spin and valley texture to the particle - hole excitation spectrum and allows the formation of spin- and valley - polarized plasmons.   when the fermi level lies in the gap of one spin in one valley, the intraband region of the corresponding spectrum disappears. for zero @xmath0 and finite @xmath1   the spin symmetry is broken and spin polarization is possible.   the lifetime and oscillator strength of the plasmons are shown to depend strongly on the number of spin and valley type electrons that form the electron - hole pairs.
we study the intrinsic, disorder - induced decoherence of an isolated quantum system under its own dynamics.   specifically, we investigate the characteristic timescale ( i.e. the decoherence time ) associated with an interacting many - body system losing the memory of its initial state. to characterize the erasure of the initial state memory,   we define a new timescale, the intrinsic decoherence time, by thresholding the gradual decay of the disorder - averaged return probability.   we demonstrate the system - size independence of the intrinsic decoherence time in different models, and we study its dependence on the disorder strength.   we find that the intrinsic decoherence time increases monotonically as the disorder strength increases in accordance with the relaxation of locally measurable quantities.   we investigate several interacting spin ( e.g. ising and heisenberg ) and fermion ( e.g. anderson and aubry - andr ) models to obtain the intrinsic decoherence time as a function of disorder and interaction strength.
we present a spectroscopic study of the four extended star clusters ( escs ) in ngc 6822 based on the data obtained with gemini multi - object spectrograph ( gmos ) on the gemini - south 8.1 m telescope.   their radial velocities derived from the spectra range from @xmath0 km s@xmath1 ( for c1 ) to @xmath2 km s@xmath1 ( for c4 ) and, unlike the intermediate age carbon stars, they do not display any sign of systematic rotation around ngc 6822.   the ages and metallicities derived using the lick indices show that the escs are old ( @xmath3 gyr ) and metal poor ( @xmath4 ).   ngc 6822 is found to have both metal poor ( @xmath5 ) and metal rich ( @xmath6 ) star clusters within 15 arcmin ( 2 kpc ) from the center, while only metal poor clusters are observed in the outer halo with @xmath7 arcmin ( 2.6 kpc ).   the kinematics, old ages, and low metallicities of escs suggest that escs may have accreted into the halo of ngc 6822.   based on the velocity distribution of escs, we have determined the total mass and the mass - to - light ratio of ngc 6822 : @xmath8 and @xmath9.   it shows that ngc 6822 is one of the most dark matter dominated dwarf galaxies in the local group.
a new family of penalty functions, adaptive to likelihood, is introduced for model selection in general regression models.   it arises naturally through assuming certain types of prior distribution on the regression parameters. to study stability properties of the penalized maximum likelihood estimator,   two types of asymptotic stability are defined.   theoretical properties, including the parameter estimation consistency, model selection consistency, and asymptotic stability, are established under suitable regularity conditions.   an efficient coordinate - descent algorithm is proposed.   simulation results and real data analysis show that the proposed method has competitive performance in comparison with existing ones.
star clusters are formed in molecular clouds which are believed to be the birth places of most stars. from recent observational data  , @xcite estimated that only 4% to 7% of the clusters embedded inside molecular clouds have survived.   an important mechanism for the disruption of embedded ( bound)-clusters is the dispersion of the parent cloud by uv radiation, stellar winds and/or supernova explosions. in this work we study the effect of this mechanism by n - body simulations.   we find that most embedded - clusters survive for more than 30 myr even when different initial conditions of the cluster may introduce some minor variations, but the general result is rather robust.       stellar dynamics - methods : n - body simulations - galaxies : star clusters.
the observation and imaging of hundreds or thousands of radio sources with the technique of very long baseline interferometry ( vlbi ) is a computationally intensive task.   however, these surveys allow us to conduct statistical investigations of large source samples, and also to discover new phenomena or types of objects.   the field of view of these high - resolution vlbi imaging observations is typically a few arcseconds at cm wavelengths. for practical reasons, often a much smaller fraction of the field  , the central region is imaged only. with an automated process we imaged the @xmath01.5-arcsec radius fields around more than 1000 radio sources, and found a variety of extended radio structures.   some of them are yet unknown in the literature.
we compare the results of numerical simulations of thin and quasi - spherical ( thick ) accretion flows with existing analytical solutions.   we use a lagrangian code based on the smooth particle hydrodynamics ( sph ) scheme and an eulerian finite difference code based on the total variation diminishing ( tvd ) scheme. in one - dimensional thin flows,   the results of the simulations, with or without shocks, agree very well with each other and with analytical solutions. in two - dimensional thick flows,   the general features, namely the locations and strengths of centrifugal and turbulent pressure supported shocks, centrifugal barriers, and the funnel walls which are expected from analytical models, agree very well, though the details vary.   generally speaking, the locations of the shocks may be better obtained by sph since the angular momentum is strictly preserved in sph, but the shocks themselves are better resolved by tvd.   the agreement of these code test results with analytical solutions provides us with confidence to apply these codes to more complex problems which we will discuss elsewhere.   = cmmi10 scaled1 = cmmi10 = cmmi7 = cmmib10 scaled1 = cmmib10 = cmmib10 scaled 833 = cmbsy10 scaled1 = cmbsy10 = cmbsy10 scaled 833 1 = 1 = 1 = 9 = 9 = 9 = 10 = 10 = 10 =
we present an extremely simplified model of multiple - domains polymer stretching in an atomic force microscopy experiment.   we portray each module as a binary set of contacts and decompose the system energy into a harmonic term ( the cantilever ) and long - range interactions terms inside each domain.   exact equilibrium computations and monte carlo simulations qualitatively reproduce the experimental saw - tooth pattern of force - extension profiles, corresponding ( in our model ) to first - order phase transitions.   we study the influence of the coupling induced by the cantilever and the pulling speed on the relative heights of the force peaks.   the results suggest that the increasing height of the critical force for subsequent unfolding events is an out - of - equilibrium effect due to a finite pulling speed.   the dependence of the average unfolding force on the pulling speed is shown to reproduce the experimental logarithmic law.
the spectra of disc accreting neutron stars generally show complex curvature, and individual components from the disc, boundary layer and neutron star surface can not be uniquely identified. here   we show that much of the confusion over the spectral form derives from inadequate approximations for comptonization and for the iron line.   there is an intrinsic low energy cutoff in comptonised spectra at the seed photon energy.   it is very important to model this correctly in neutron star systems as these have expected seed photon temperatures ( from either the neutron star surface, inner disc or self  absorbed cyclotron ) of @xmath0 kev, clearly within the observed x  ray energy band.   there is also reflected continuum emission which must accompany the observed iron line, which distorts the higher energy spectrum.   we illustrate these points by a reanalysis of the _ ginga _ spectra of cyg x2 at all points along its z track, and show that the spectrum can be well fit by models in which the low energy spectrum is dominated by the disc, while the higher energy spectrum is dominated by comptonised emission from the boundary layer, together with its reflected spectrum from a relativistically smeared, ionised disc.   accretion, accretion discs, radiation mechanisms : thermal, binaries : close, stars : individual : cyg x-2, stars : neutron, x - rays : stars
the hades first level trigger is studied for the system p+ni at a beam energy of 2 agev.   the timing properties of the trigger signal are reported. the efficiency loss due to deadtime   is specified.   a trigger requirement of a time overlap window with the start detector is described.   the trigger rates for different overlap windows are given.
the low temperature phase diagram of @xmath0he adsorbed on a single graphene sheet is studied by computer simulations of a system consisting of nearly a thousand helium atoms. in the first layer   two commensurate solid phases are observed with fillings @xmath1 and @xmath2, respectively, separated by a domain wall phase, as well as an incommensurate crystal at a higher coverage.   no evidence of a thermodynamically stable superfliuid phase is found for the first adlayer.   second layer promotion occurs at a coverage of 0.111(4 )  @xmath3. in the second layer   two phases are observed, namely a superfluid and an incommensurate solid, with no commensurate solid intervening between these two phases.   the computed phase diagram closely resembles that predicted for helium on graphite.
0957 + 561 is the first gravitational lens system to be discovered and first for which a time delay was measured.   because the system is unusually rich in observables such as image positions, fluxes, vlbi structure, and polarization it has been modelled quite extensively.   however, since it resides in a cluster providing substantial convergence, the velocity dispersion of the lensing galaxy is an important component to models.   we have measured this dispersion to be @xmath0  ( 1-sigma ), which implies a hubble constant of @xmath1  ( 1-sigma ) according to the preferred fgs model of grogin and narayan, and @xmath2  ( 1-sigma ) using the spls model.   the unknown velocity dispersion anisotropy of the central galaxy produces an additional uncertainty of perhaps 15% or more.   we see no variation in dispersion with position to a radius of @xmath3.   in addition to a galaxy from the background cluster at @xmath4, our slit serendiptously picked up a galaxy at @xmath5, and two galaxies which may be part of a background cluster at a redshift of @xmath6.   _ subject headings : cosmology  distance scale  gravitational lensing  quasars : individual ( 0957 + 561 ) _    # 1#1    = cmr8
we present measurements of the fundamental plane ( fp ) parameters ( the effective radius, the mean effective surface brightness, and the central velocity dispersion ) of six field elliptical galaxies at intermediate redshift.   the imaging is taken from the medium deep survey of the hubble space telescope, while the kinematical data are obtained from long - slit spectroscopy using the 3.6-m eso telescope.   the fundamental plane appears well defined in the field even at redshift @xmath0 0.3.   the data show a shift in the fp zero point with respect to the local relation, possibly indicating modest evolution, consistent with the result found for intermediate redshift cluster samples.   the fp slopes derived for our field data, plus other cluster ellipticals at intermediate redshift taken from the literature, differ from the local ones, but are still consistent with the interpretation of the fp as a result of homology, of the virial theorem and of the existence of a relation between luminosity and mass, @xmath1.   we also derive the surface brightness vs. effective radius relation for nine galaxies with redshift up to @xmath2, and data from the literature ; the evolution that can be inferred is consistent with what is found using the fp.   galaxies : elliptical and lenticular, cd  galaxies : evolution  galaxies : photometry  galaxies : kinematics and dynamics  galaxies : fundamental parameters  galaxies : formation
we investigate two - dimensional ( 2d ) states of bose - einstein condensates ( bec ) with self - attraction or self - repulsion, trapped in an axially symmetric optical - lattice potential periodic along the radius.   unlike previously studied 2d models with bessel lattices, no localized states exist in the linear limit of the present model, hence all localized states are truly nonlinear ones.   we consider the states trapped in the central potential well, and in remote circular troughs. in both cases, a new species, in the form of _ radial gap solitons _, are found in the repulsive model ( the gap soliton trapped in a circular trough may additionally support stable dark - soliton pairs ). in remote troughs  , stable localized states may assume a ring - like shape, or shrink into strongly localized solitons.   the existence of stable annular states, both azimuthally uniform and weakly modulated ones, is corroborated by simulations of the corresponding gross - pitaevskii equation.   dynamics of strongly localized solitons circulating in the troughs is also studied. while the solitons with sufficiently small velocities are stable, fast solitons gradually decay, due to the leakage of matter into the adjacent trough under the action of the centrifugal force.   collisions between solitons are investigated too.   head - on collisions of in - phase solitons lead to the collapse ; @xmath0-out of phase solitons bounce many times, but eventually merge into a single soliton without collapsing.
it is widely held that plane wave spacetimes are causally well behaved which means that they are free from causal pathologies such as closed timelike curves or closed null geodesics. in this paper, we show that one can get closed null geodesics in a plane wave metric by analytically solving the geodesic equations.   = 18 pt    * d. sarma *, * m. patgiri * and * f. ahmed * + _ department of physics, cotton college, _ + _ guwahati-781001, india _    _   keywords : _ vacuum spacetimes, closed null geodesics, plane wave spacetimes + _ pacs numbers : _ 04.20.jb, 04.20.gz
we report the first detailed spectroscopic observations of the recently identified intermediate polar rxj0028.8 + 5917/v709 cas.   we discovered that the system shows significant ew @xmath0(2 - 4) broad absorptions affecting the balmer lines from h@xmath1 to h@xmath2.   these broad absorptions are interpreted as the contribution of an underlying da logg=8 white dwarf at a temperature of @xmath023 000 k, contributing @xmath017 % ( at 4500  ) to the overall flux.   this is the first direct detection of a white dwarf in an intermediate polar system.   the absence of significant zeeman splitting indicates a magnetic field lower than 10 mg, confirming that, at least in some cases, intermediate polars have weaker fields than polars.   # 1 1.25 in.125 in.25 in
the paper presents partial - realization theory and realization algorithms for linear switched systems.   linear switched systems are a particular subclass of hybrid systems.   we formulate a notion of a partial realization and we present conditions for existence of a minimal partial realization.   we propose two partial - realization algorithms and we show that under certain conditions they yield a complete realization.   our main tool is the theory of rational formal power series.   hybrid systems, linear switched systems,, partial - realization theory, realization algorithm, formal power series 93b15, 93b20, 93b25, 93c99
plasma proteins such as fibrinogen induce the aggregation of red blood cells ( rbc ) into rouleaux, which are responsible for the pronounced shear thinning behavior of blood, control the erythrocyte sedimentation rate ( esr )  a common hematological test  and are involved in many situations of physiological relevance such as structuration of blood in the microcirculation or clot formation in pathological situations.   confocal microscopy is used to characterize the shape of rbcs within rouleaux at equilibrium as a function of macromolecular concentration, revealing the diversity of contact zone morphology.   three different configurations that have only been partly predicted before are identified, namely parachute, male - female and sigmoid shapes, and quantitatively recovered by numerical simulations.   a detailed experimental and theoretical analysis of clusters of two cells shows that the deformation increases nonlinearly with the interaction energy.   models indicate a forward bifurcation in which the contacting membrane undergoes a buckling instability from a flat to a deformed contact zone at a critical value of the interaction energy.   these results are not only relevant for the understanding of the morphology and stability of rbc aggregates, but also for a whole class of interacting soft deformable objects such as vesicles, capsules or cells in tissues.
timing of high - count rate sources with the _ nustar_small explorer mission requires specialized analysis techniques. _ nustar_was primarily designed for spectroscopic observations of sources with relatively low count - rates rather than for timing analysis of bright objects.   the instrumental dead time per event is relatively long ( @xmath02.5  msec ), and varies by a few percent event - to - event.   the most obvious effect is a distortion of the white noise level in the power density spectrum ( pds ) that can not be modeled easily with the standard techniques due to the variable nature of the dead time. in this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cross power density spectrum to obtain a good proxy of the white noise - subtracted pds.   thereafter, one can use a monte carlo approach to estimate the remaining effects of dead time, namely a frequency - dependent modulation of the variance and a frequency - independent drop of the sensitivity to variability. in this way,   most of the standard timing analysis can be performed, albeit with a sacrifice in signal to noise relative to what would be achieved using more standard techniques.   we apply this technique to _   nustar_observations of the black hole binaries gx339@xmath14, cygx-1and grs1915@xmath2105.
we consider the interaction between dark matter and dark energy in the framework of holographic dark energy, and propose a natural and physically plausible form of interaction, in which the interacting term is proportional to the product of the powers of the dark matter and dark energy densities.   we investigate the cosmic evolution in such models.   the impact of the coupling on the dark matter and dark energy components may be asymmetric. while the dark energy decouples from the dark matter at late time, just as other components of the cosmic fluid become decoupled as the universe expands, interestingly, the dark matter may actually become coupled to the dark energy at late time.   we shall call such a phenomenon as _   incoupling_. we use the latest type ia supernovae data from the scp team, baryon acoustics oscillation data from sdss and 2df surveys, and the position of the first peak of the cmb angular power spectrum to constrain the model.   we find that the interaction term which is proportional to the first power product of the dark energy and dark matter densities gives an excellent fit to the current data.
by applying density functional theory ( dft ) approximations, we present a first - principles investigation of elastic properties for the experimentally verified phases of a metallic perovskite lanio@xmath0. in order to improve the accuracy of calculations, at first we select the most appropriate dft approaches according to their performance in reproducing the low - temperature crystalline structure and the electronic density of states observed for the bulk lanio@xmath0.   then, we continue with the single - crystal elastic constants and mechanical stability for the most common rhombohedral as well as high - temperature cubic and strain - induced monoclinic phases. together with the calculated single - crystal elastic constants, the deduced polycrystalline properties, including bulk, shear, and young s moduli, poisson s ratio, vickers hardness, sound velocities, debye temperature, and anisotropy indexes, remedy the existing gap of knowledge about the elastic and mechanical behaviour of lanio@xmath0, at least from a theoretical standpoint.
in this paper, a reconstruction method for the spatially distributed dielectric constant of a medium from the back scattering wave field in the frequency domain is considered.   our approach is to propose a globally convergent algorithm, which does not require any knowledge of a small neighborhood of the solution of the inverse problem in advance.   the quasi - reversibility method ( qrm ) is used in the algorithm.   the convergence of the qrm is proved via a carleman estimate.   the method is tested on both computationally simulated and experimental data.    _   2010 mathematics subject classification : _   34l25, 35p25, 35r30, 78a46.   _ keywords : _ coefficient inverse scattering problem, globally convergent algorithm, dielectric constant, electromagnetic waves.
the _ kepler mission _ seeks to detect earth - size planets transiting solar - like stars in its @xmath0115 deg@xmath1 field of view over the course of its 3.5 year primary mission by monitoring the brightness of each of @xmath0156,000 long cadence stellar targets with a time resolution of 29.4 minutes.   we discuss the photometric precision achieved on timescales relevant to transit detection for data obtained in the 33.5-day long quarter 1 ( q1 ) observations that ended 2009 june 15.   the lower envelope of the photometric precision obtained at various timescales is consistent with expected random noise sources, indicating that _ kepler _ has the capability to fulfill its mission.   the _ kepler _ light curves exhibit high precision over a large dynamic range, which will surely permit their use for a large variety of investigations in addition to finding and characterizing planets.   we discuss the temporal characteristics of both the raw flux time series and the systematic error - corrected flux time series produced by the _ kepler _ science pipeline, and give examples illustrating _ kepler s _ large dynamic range and the variety of light curves obtained from the q1 observations.
quasar absorption lines provide detailed information on the chemical, kinematic, and ionization conditions in galaxies and their environments, and provide a means for studying the evolution of these conditions back to the epoch of the first quasars. among the collection of absorbing structures along the lines of sight to quasars there is an evolutionary sequence of galaxies that represent predecessors of the milky way and provide a direct view of its history.   absorption spectra of lines of sight through the milky way and through nearby galaxies reveal a variety of chemical species, ionization conditions, and kinematic substructures.   these absorption profiles are produced by low density gas distributed in rotating disks, high velocity halo clouds, satellite galaxies and their debris, superbubbles, and other sub  galactic gaseous fragments.   guided by knowledge gained by studying nearby galaxies, we are developing interpretations of the variety of observed absorption signatures. images of @xmath0 galaxies responsible for absorption also allow us to explore the statistical connections between the galaxy properties and their gaseous content.   quasar absorption lines are fast becoming a powerful evolutionary probe of gaseous conditions in the milky way.    2
a phenomenological formalism is presented in which the apparent acceleration of the universe is generated by cosmic structure formation, without resort to dark energy, modifications to gravity, or a local void.   the observed acceleration results from the combined effect of innumerable local perturbations due to individually virializing systems, overlapping together in a smoothly - inhomogeneous adjustment of the frw metric, in a process governed by the causal flow of inhomogeneity information outward from each clumped system. after noting how common arguments claiming to limit backreaction are physically unrealistic, models are presented which fit the supernova luminosity distance data essentially as well as @xmath0cdm, while bringing several important cosmological parameters to a new concordance.   these goals are all achieved with a second - generation version of our formalism that accounts for the negative feedback of causal backreaction upon itself due to the slowed propagation of gravitational inhomogeneity information.
starting from considerations about meaning and subsequent use of asymmetric uncertainty intervals of experimental results, we review the issue of uncertainty propagation.   we show that, using a probabilistic approach ( the so - called bayesian approach ), all sources of uncertainty can be included in a logically consistent way.   practical formulae for the first moments of the probability distribution are derived up to second - order approximations.
we propose and test a wavelet transform modulus maxima method for the automated detection and extraction of coronal loops in extreme ultraviolet images of the solar corona.   this method decomposes an image into a number of size scales and tracks enhanced power along each ridge corresponding to a coronal loop at each scale.   we compare the results across scales and suggest the optimum set of parameters to maximise completeness while minimising detection of noise. for a test coronal image, we compare the global statistics ( _ e.g., _ number of loops at each length ) to previous automated coronal - loop detection algorithms.
we present predictions of the correlation between the ly@xmath0 forest absorption in quasar spectra and the mass within @xmath1 ( comoving ) of the line of sight, using fully hydrodynamic and hydro - pm numerical simulations of the cold dark matter model supported by present observations.   the observed correlation based on galaxies and the ly@xmath0 forest can be directly compared to our theoretical results, assuming that galaxies are linearly biased on large scales.   specifically, we predict the average value of the mass fluctuation, @xmath2, conditioned to a fixed value of the ly@xmath0 forest transmitted flux @xmath3, after they have been smoothed over a @xmath4 cube and line of sight interval, respectively.   we find that @xmath5 as a function of @xmath6 has a slope of @xmath7 at this smoothing scale, where @xmath8 and @xmath9 are the rms dispersions ( this slope should decrease with the smoothing scale ).   we show that this value is largely insensitive to the cosmological model and other ly@xmath0 forest parameters.   comparison of our predictions to observations should provide a fundamental test of our ideas on the nature of the ly@xmath0 forest and the distribution of galaxies, and can yield a measurement of the bias factor of any type of galaxies that are observed in the vicinity of ly@xmath0 forest lines of sight.
dark matter may be composed of superwimps, superweakly - interacting massive particles produced in the late decays of other particles.   we focus on the case of gravitinos produced in the late decays of sleptons or sneutrinos and assume they are produced in sufficient numbers to constitute all of non - baryonic dark matter.   at leading order, these late decays are two - body and the accompanying energy is electromagnetic. for natural weak - scale parameters, these decays have been shown to satisfy bounds from big bang nucleosynthesis and the cosmic microwave background.   however, sleptons and sneutrinos may also decay to three - body final states, producing hadronic energy, which is subject to even more stringent nucleosynthesis bounds.   we determine the three - body branching fractions and the resulting hadronic energy release.   we find that superwimp gravitino dark matter is viable and determine the gravitino and slepton / sneutrino masses preferred by this solution to the dark matter problem. in passing,   we note that hadronic constraints disfavor the possibility of superwimps produced by neutralino decays unless the neutralino is photino - like.
the charge - current - induced spin polarization is a key property of topological insulators for their applications in spintronics.   however, topological surface states are expected to give rise to only one type of spin polarization for a given current direction, which has been a limiting factor for spin manipulations. here   we report that in devices based on the bulk - insulating topological insulator bisbtese@xmath0, an unexpected switching of spin polarization was observed upon changing the chemical potential.   the spin polarization expected from the topological surface states was detected in a heavily electron - doped device, whereas the opposite polarization was reproducibly observed in devices with low carrier densities.   we propose that the latter type of spin polarization stems from topologically - trivial two - dimensional states with a large rashba spin splitting, which are caused by a strong band bending at the surface of bisbtese@xmath0 beneath the ferromagnetic electrode used as a spin detector.   this finding paves the way for realizing the  spin transistor " operation in future topological spintronic devices.
a simple model describing depolarization channels with zero - bandwidth environment is presented and exactly solved.   the environment is modelled by lorentzian, telegraphic and gaussian zero - bandwidth noises.   such channels can go beyond the standard markov dynamics and therefore can illustrate the influence of memory effects of the noisy communication channel on the transmitted information. to quantify the disturbance of quantum states the entanglement fidelity between arbitrary input and output states is investigated.
a century ago, in 1911 and 1913, plummer and then reynolds introduced their models to describe the radial distribution of stars in ` nebulae '.   this article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies.   the quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cd galaxy envelopes, are discussed.   issues pertaining to spiral galaxies including dust, bulge - to - disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed.   an array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. these ` redshift zero'relations not only quantify the behavior and nature of galaxies in the universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, @xmath0-body - simulations or semi - analytical modelling.   for example, it is shown that some of the recently discovered compact elliptical galaxies at @xmath1 may be the bulges of modern disc galaxies.
during the beam commissioning of the large hadron collider ( lhc )  @xcite with 150, 75, 50 and 25-ns bunch spacing, important electron - cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed.   a method has been developed to infer different key beam - pipe surface parameters by benchmarking simulations and pressure rise observed in the machine.   this method allows us to monitor the scrubbing process ( i.e.  the reduction of the secondary emission yield as a function of time ) in the regions where the vacuum - pressure gauges are located, in order to decide on the most appropriate strategies for machine operation. in this paper   we present the methodology and first results from applying this technique to the lhc.
we present a new statistic  the redshift dispersion which may prove useful for comparing next generation redshift surveys ( e.g., the sloan digital sky survey ) and cosmological simulations.   our statistic is specifically designed for the projection of phase space which is directly measured by redshift surveys.   we find that the redshift dispersion of galaxies as a function of the projected overdensity has a strong dependence on the cosmological density parameter @xmath0.   the redshift dispersion statistic is easy to compute and can be motivated by applying the cosmic virial theorem to subsets of galaxies with the same local density.   we show that the velocity dispersion of particles in these subsets is proportional to the product of @xmath0 and the local density.   low resolution n - body simulations of several cosmological models ( open / closed cdm, cdm+@xmath1, hdm ) indicate that the proportionality between velocity dispersion, local density and @xmath0 holds over redshift scales in the range 50 @xmath2 to 500 @xmath2.   the redshift dispersion may provide an interesting means for comparing volume - limited subsamples of the sloan digital sky survey to equivalent n - body / hydrodynamics simulations.    # 1#1
a numerical investigation of two locally applied drag reducing control schemes is carried out in the configuration of a spatially developing turbulent boundary layer ( tbl ).   one control is designed to damp near - wall turbulence and the other induces constant mass flux in the wall - normal direction. both control schemes yield similar local drag reduction rates within the control region. however, the flow development downstream of the control significantly differs : persistent drag reduction is found for the uniform blowing case whereas drag increase is found for the turbulence damping case. in order to account for this difference the formulation of a global drag reduction rate is suggested.   it represents the reduction of the streamwise force exerted by the fluid on a finite length plate.   furthermore, it is shown that the far downstream development of the tbl after the control region can be described by a single quantity, namely a streamwise shift of the uncontrolled boundary layer, i.e. a changed virtual origin.   based on this result, a simple model is developed that allows relating for the local drag reduction rate to the global one without the need of conducting expensive simulations or measurements far downstream of the control region.   boundary layer control, drag reduction, turbulent boundary layers
we present an implementation of the hierarchical tree algorithm on the individual timestep algorithm ( the hermite scheme ) for collisional @xmath0-body simulations, running on grape-9 system, a special - purpose hardware accelerator for gravitational many - body simulations.   such combination of the tree algorithm and the individual timestep algorithm was not easy on the previous grape system mainly because its memory addressing scheme was limited only to sequential access to a full set of particle data.   the present grape-9 system has an indirect memory addressing unit and a particle memory large enough to store all particles data and also tree nodes data.   the indirect memory addressing unit stores interaction lists for the tree algorithm, which is constructed on host computer, and, according to the interaction lists, force pipelines calculate only the interactions necessary. in our implementation, the interaction calculations are significantly reduced compared to direct @xmath1 summation in the original hermite scheme. for example, we can archive about a factor 30 of speedup ( equivalent to about 17 teraflops ) against the hermite scheme for a simulation of @xmath2 system, using hardware of a peak speed of 0.6 teraflops for the hermite scheme.
hadron collider signatures of new physics are investigated in which a primary resonance is produced that decays to a secondary resonance by emitting a w - boson, with the secondary resonance decaying to two jets.   this topology can arise in supersymmetric theories with @xmath0-parity violation where the lightest supersymmetric particles are either a pair of squarks, or a slepton - sneutrino pair.   the resulting signal can have a cross section consistent with the @xmath1 observation reported by the cdf collaboration, while remaining consistent with earlier constraints.   other observables that can be used to confirm this scenario include a significant charge asymmetry in the same channel at the lhc. with strongly interacting resonances such as squarks,   pair production topologies additionally give rise to 4 jet and w@xmath2w@xmath3 + 4 jet signatures, each with two equal - mass dijet resonances within the 4 jets.   ru - nhetc-2011 - 07 + 1.3 in * signatures of resonant super - partner * + * production with charged - current decays * 0.65 in can kilic and 0.25 in     _ new high energy theory center + department of physics + rutgers university + piscataway, nj 08854 _    0.75 in
we argue that the superconducting state found in high-@xmath0 cuprates is inhomogeneous with a corresponding inhomogeneous superfluid density.   we introduce two classes of microscopic models which capture the magnetic and superconducting properties of these strongly correlated materials.   we start from a generalized @xmath1-@xmath2 model, in which appropriate inhomogeneous terms mimic stripes.   we find that inhomogeneous interactions that break magnetic symmetries are essential to induce substantial pair binding of holes in the thermodynamic limit.   we argue that this type of model reproduces the arpes and neutron scattering data seen experimentally.
`` net neutrality '' often refers to the policy dictating that an internet service provider ( isp ) can not charge content providers ( cps ) for delivering their content to consumers.   many past quantitative models designed to determine whether net neutrality is a good idea have been rather equivocal in their conclusions.   here we propose a very simple two - sided market model, in which the types of the consumers and the cps are _ power - law distributed _  a kind of distribution known to often arise precisely in connection with internet - related phenomena.   we derive mostly analytical, closed - form results for several regimes : ( a ) net neutrality, ( b ) social optimum, ( c ) maximum revenue by the isp, or ( d ) maximum isp revenue under quality differentiation.   one unexpected conclusion is that ( a ) and ( b ) will differ significantly, unless average cp productivity is very high.
in this paper, we describe the design, construction and performance of an apparatus installed in the aberdeen tunnel laboratory in hong kong for studying spallation neutrons induced by cosmic - ray muons under a vertical rock overburden of 611 meter water equivalent ( m.w.e. ).   the apparatus comprises of six horizontal layers of plastic - scintillator hodoscopes for determining the direction and position of the incident cosmic - ray muons. sandwiched between the hodoscope planes   is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of gadolinium by weight for improving the efficiency of detecting the spallation neutrons.   performance of the apparatus is also presented.   aberdeen tunnel, hong kong, underground, cosmic - ray muon, neutron 25.30.mr, 29.40.mc, 29.40.vj, 95.55.vj, 96.40.tv
interactions are known to have dramatic effects on bosonic gases in one dimension ( 1d ).   not only does the ground state transform from a condensate - like state to an effective fermi sea, but new fundamental excitations, which do not have any higher - dimensional equivalents, are predicted to appear. in this work,   we trace these elusive excitations via their effects on the dynamical structure factor of 1d strongly - interacting bose gases at low temperature.   an array of 1d bose gases is obtained by loading a @xmath0rb condensate in a 2d lattice potential.   the dynamical structure factor of the system is probed by energy deposition through low - momentum bragg excitations.   the experimental signals are compared to recent theoretical predictions for the dynamical structure factor of the lieb - liniger model at @xmath1.   our results demonstrate that the main contribution to the spectral widths stems from the dynamics of the interaction - induced excitations in the gas, which can not be described by the luttinger liquid theory.
we give an arithmetical proof of the strong normalization of the @xmath0-calculus ( and also of the @xmath1-calculus ) where the type system is the one of simple types with recursive equations on types.   the proof using candidates of reducibility is an easy extension of the one without equations but this proof can not be formalized in peano arithmetic.   the strength of the system needed for such a proof was not known.   our proof shows that it is not more than peano arithmetic.
the mitotic spindle is an important intermediate structure in eucaryotic cell division, in which each of a pair of duplicated chromosomes is attached through microtubules to centrosomal bodies located close to the two poles of the dividing cell.   it is widely believed that the spindle starts forming by the ` capture'of chromosome pairs, held together by kinetochores, by randomly searching microtubules.   we present a complete analytical formulation of this problem, in the case of a single fixed target and for arbitrary cell size.   we derive a set of green s functions for the microtubule dynamics and an associated set of first passage quantities. an implicit analytical expression for the probability distribution of the search time   is then obtained, with appropriate boundary conditions at the outer cell membrane.   we extract the conditions of optimized search from our formalism.   our results are in qualitative and semi - quantitative agreement with known experimental results for different cell types.
the high - mass star - forming site g009.62 + 00.20e hosts the 6.7ghz methanol maser source with the greatest flux density in the galaxy which has been flaring periodically over the last ten years.   we performed high - resolution astrometric measurements of the ch@xmath0oh, h@xmath1o, and oh maser emission and 7  mm continuum in the region.   the radio continuum emission was resolved in two sources separated by 1300  au.   the ch@xmath0oh maser cloudlets are distributed along two north - south ridges of emission to the east and west of the strongest radio continuum component.   this component likely pinpoints a massive young stellar object which heats up its dusty envelope, providing a constant ir pumping for the class   ch@xmath0oh maser transitions.   we suggest that the periodic maser activity may be accounted for by an independent, pulsating, ir radiation field provided by a bloated protostar in the vicinity of the brightest masers.   we also report about the discovery of an elliptical distribution of ch@xmath0oh maser emission in the region of periodic variability.
events of giant conductance and anomalies of the phase transmission time for holes, are theoretically investigated within the multicomponent scattering approach.   based on this model, new analytical expressions for unitarity relations in the uncoupled hole transport are obtained and directly applied to study the behavior of the conductance and the phase transmission time in a double barrier resonant tunneling ( dbrt ) and a superlattice @xmath0-cladding layer@xmath1-cladding layer.   clear - signature evidences of giant conductance phenomena for hole transmission without valence - band mixing through a dbrt and a superlattice were found.   the giant conductance effect losses robustness by manipulating the number of superlattice layers and by including the valence - band particles coupling as well.   phase time through the heterostructure exhibits extremal dependencies in the gaps and in the barriers, as those reported before for electrons.   we have detected an earlier arrival phase time for the propagation of both flavors of holes within the barrier, in the order of few tenths of picoseconds.   an appealing filter - like effect is presented, whenever a selective confinement strength arises independently for both flavors of holes in the uncoupled regime.   our results also prescribe noticeable evidences for both uncoupled and coupled hole fluxes, similar to those foretold by hartman, upon transmission of electrons through opaque barriers.   tunneling, phase time, elastic quantum scattering 73.43.jn, 34.80.bm
some general properties of extensive air showers are discussed.   the main focus is put on the longitudinal development, in particular the energy flow, and on the lateral distribution of different air shower components.   the intention of the paper is to provide a basic introduction to the subject rather than a comprehensive review.
the off - axis location of the advanced camera for surveys ( acs ) is the chief ( but not sole ) cause of strong geometric distortion in all detectors : the wide field camera ( wfc ), high resolution camera ( hrc ), and solar blind camera ( sbc ). dithered observations of rich star cluster fields are used to calibrate the distortion.   we describe the observations obtained, the algorithms used to perform the calibrations and the accuracy achieved.
in this proceeding we present the procedure that we have adopted to obtain a dataset of padova94 tracks ( @xcite ) interpolated in metallicity.   the procedure requires special care to avoid spurious features in the resulting grid, thus we have subdivided tracks in evolutionary phases, we have chosen the suitable interpolation method and the transition masses.   finally, we have compared our interpolated dataset with a similar models, @xcite, obtaining a general good agreement.
the two dimensional incompressible viscous flow past a flapping foil immersed in a uniform stream is studied numerically.   numerical simulations were performed using a lattice - boltzmann model for moderate reynolds numbers.   the computation of the hydrodynamic force on the foil is related to the the wake structure. in particular, when the foil s centre of mass is fixed in space, numerical results suggest a relation between drag coefficient behaviour and the flapping frequency which determines the transition from the von krmn ( vkm ) to the inverted von krmn wake. beyond the inverted vkm transition   the foil was released.   upstream swimming was observed at high enough flapping frequencies.   computed hydrodynamic forces suggest the propulsion mechanism for the swimming foil.
the roth s two - pole approximation has been used by the present authors to investigate the role of @xmath0 hybridization in the superconducting properties of an extended @xmath0 hubbard model.   superconductivity with singlet @xmath1-wave pairing is treated by following beenen and edwards formalism. in this work,   the coulomb interaction, the temperature and the superconductivity have been considered in the calculation of some relevant correlation functions present in the roth s band shift.   the behavior of the order parameter associated with temperature, hybridization, coulomb interaction and the roth s band shift effects on superconductivity are studied.
we describe systematic changes in the centroid frequencies and the splitting coefficients as found using data from mdi on board soho, covering cycle 23.   the data allow us to construct a seismic map of the evolving solar activity  covering all latitudes. at lower latitudes  , the temporal evolution closely tracks that of _ butterfly diagram_. the additional information from higher latitudes in the map is of a significant activity in the polar region, peaking at activity minimum in 1996.   the most plausible source of solar oscillation frequency changes over the solar cycle is the evolution of the radial component of the small - scale magnetic field.   the amplitude of the required mean field changes is @xmath0 g at the photosphere, and increasing going inward.
we introduce and investigate the ribbon groupoid associated with a garside group. under a technical hypothesis, we prove that this category is a garside groupoid.   we decompose this groupoid into a semi - direct product of two of its parabolic subgroupoids and provide a groupoid presentation. in order to established the latter result  , we describe quasi - centralizers in garside groups.   all results hold in the particular case of artin - tits groups of spherical type.
in the framework of first - principles calculations, we investigate the structural and electronic properties of graphene in contact with as well as sandwiched between ws@xmath0 and wse@xmath0 monolayers.   we report the modification of the band characteristics due to the interaction at the interface and demonstrate that the presence of the dichalcogenides results in quantum spin hall states in the absence of a magnetic field.
we present 3 mm observations obtained with the iram 30-m telescope for ten nearby gas - rich active galaxies spanning three orders of magnitude in infrared luminosity.   emission lines of hco@xmath0(1 - 0 ), hcn(1 - 0 ), and c@xmath1h(1 - 0 ) were simultaneously detected in most galaxies of our sample.   we also tentatively detected the rare isotopic species, h@xmath2cn, hc@xmath3n and h@xmath2co@xmath0 in up to four galaxies ( ic694, ngc3690, ngc4258 and ngc6240 ).   our estimation shows that the optical depth of hcn is low to moderate in these galaxies ( @xmath4. after comparing the intensity ratios of different molecular emission lines ( hcn / hco@xmath0, c@xmath1h / hcn, and c@xmath1h / hco@xmath0 ) with the infrared luminosity ( @xmath5 )  , we find that in the infrared luminous sample of five composite ( agn+starburst ) galaxies, these ratios vary with @xmath5 : the hcn / hco@xmath0 ratio increases with @xmath5, which is consistent with previous studies, while there is a slight trend in the composite galaxies that both c@xmath1h / hcn and c@xmath1h / hco@xmath0 ratios decrease with increasing @xmath5.   although our sample is limited, this trend may possibly imply a relation between the overall gas density and the infrared luminosity of galaxies.       galaxies : active  galaxies : ism  galaxies : evolution  ism : molecules
confinement has generally the effect of suppressing order in condensed matter. indeed, phase transitions such as freezing, or the superfluid transition in liquid helium, occur at lower temperatures in confinement than they do in the bulk.   we provide here an illustration of a physical setting in which the opposite takes place.   specifically, the enhancement of the superfluid response of parahydrogen confined to nanoscale size cavities is demonstrated by means of first principle computer simulations.   prospects to stabilize and observe the long sought but yet elusive bulk superfluid phase of parahydrogen in purposefully designed porous media are discussed.
realistic 3-dimensional ( 3d ), radiative hydrodynamical surface convection simulations of the metal - poor halo stars hd140283 and hd84937 have been performed. due to the dominance of adiabatic cooling over radiative heating   very low atmospheric temperatures are encountered.   the lack of spectral lines in these metal - poor stars thus causes much steeper temperature gradients than in classical 1d hydrostatic model atmospheres where the temperature of the optically thin layers is determined by radiative equilibrium. the modified atmospheric structures cause changes in the emergent stellar spectra.   in particular, the primordial li abundances may have been overestimated by 0.2 - 0.35dex with 1d model atmospheres.   however, we caution that our result assumes local thermodynamic equilibrium ( lte ), while the steep temperature gradients may be prone to e.g. over - ionization.
holonomic gates for quantum computation are commonly considered to be robust against certain kinds of parametric noise, the very motivation of this robustness being the geometric character of the transformation achieved in the adiabatic limit. on the other hand,   the effects of decoherence are expected to become more and more relevant when the adiabatic limit is approached.   starting from the system described by florio _   et al. _   [ phys.   rev.   a * 73 *, 022327 ( 2006 ) ], here we discuss the behavior of non ideal holonomic gates at finite operational time, i.e., far before the adiabatic limit is reached.   we have considered several models of parametric noise and studied the robustness of finite time gates.   the obtained results suggest that the finite time gates present some effects of cancellation of the perturbations introduced by the noise which mimic the geometrical cancellation effect of standard holonomic gates.   nevertheless, a careful analysis of the results leads to the conclusion that these effects are related to a _   dynamical _ instead of geometrical feature.
we discuss the event rate in deepcore array due to neutrino flux produced by annihilations and decays of galactic dark matter.   this event rate is calculated with a 10 gev threshold energy, which is smaller than the threshold energy taken in previous works.   taking into account the background event rate due to the atmospheric neutrino flux, we evaluate the sensitivity of deepcore array for probing dark matter annihilation cross section and decay time.   the sensitivity studies include the annihilation modes @xmath0,  @xmath1, and @xmath2, and decay modes @xmath3,  @xmath1, and @xmath2.   we compare our results with corresponding constraints derived from observations of wmap, act and fermi - lat.   = = = = = = = = = ==================== = =======
the analysis of clouds in the earth s atmosphere is important for a variety of applications, viz.   weather reporting, climate forecasting, and solar energy generation. in this paper, we focus our attention on the impact of cloud on the total solar irradiance reaching the earth s surface.   we use weather station to record the total solar irradiance.   moreover, we employ collocated ground - based sky camera to automatically compute the instantaneous cloud coverage.   we analyze the relationship between measured solar irradiance and computed cloud coverage value, and conclude that higher cloud coverage greatly impacts the total solar irradiance.   such studies will immensely help in solar energy generation and forecasting.
inverse bicontinuous cubic phases are ubiquitous in lipid - water mixtures and consist of a lipid bilayer forming a cubic minimal surface, thereby dividing space into two cubic networks of water channels. for small hydrocarbon chain lengths,   the monolayers can be modeled as parallel surfaces to a minimal midsurface.   the bending energy of the cubic phases is determined by the distribution of gaussian curvature over the minimal midsurfaces which we calculate for seven different structures ( g, d, p, i - wp, c(p ), s and f - rd ).   we show that the free - energy densities of the structures g, d and p are considerably lower than those of the other investigated structures due to their narrow distribution of gaussian curvature.   the bonnet transformation between g, d, and p implies that these phases coexist along a triple line, which also includes an excess water phase.   our model includes thermal membrane undulations.   our qualitative predictions remain unchanged when higher order terms in the curvature energy are included.   calculated phase diagrams agree well with the experimental results for 2:1 lauric acid / dilauroyl phosphatidylcholine and water.    # 1eq.   (  ) # 1tab  .   # 1fig.    # 1sec.   
starting from a set of coupled boltzmann equations, we investigate the thermalization of a two - species cold atomic gas confined either in a box or in an isotropic harmonic trap.   we show that the thermalization times, by contrast to the collision rate, depend on the interferences between scattering partial waves.   the dynamics of thermalization in a harmonic trap is also strongly dependent upon the ratio between the collision rate and the trap frequencies.
the magnon dispersion of ca@xmath0ruo@xmath1 has been studied by polarized and unpolarized neutron scattering experiments on crystals containing 0, 1 and 10  % of ti.   the entire dispersion of transverse magnons can be well described by a conventional spin - wave model with interaction and anisotropy parameters that agree with density functional theory calculations.   spin - orbit coupling strongly influences the magnetic excitations, which is most visible in large energies of the magnetic zone - center modes arising from magnetic anisotropy.   we find evidence for a low - lying additional mode that exhibits strongest scattering intensity near the antiferromagnetic zone center.   this extra signal can be explained by a sizable magnetic moment of 0.11 bohr magnetons on the apical oxygens parallel to the ru moment, which is found in the density functional theory calculations.   the energy and the signal strength of the additional branch are well described by taking into account this oxygen moment with weak ferromagnetic coupling between ru and o moments.
the mass and decay constant of the ground state strange tensor meson @xmath0 with @xmath1 is calculated using the qcd sum rules method.   the results are consistent with the experimental data.   it is found that su(3 ) symmetry breaking effect constitutes about @xmath2 of the decay constant.
the early evolution of planetary systems is expected to depend on various periods of disk matter accretion onto the central star, which may include the accretion of metal - rich matter after the star settles on the main sequence.   when this happens, the accreted material is rapidly mixed within the surface convective zone and induces an inverse mean - molecular - weight gradient, unstable for thermohaline convection.   the induced mixing, which dilutes the metal excess, may also have important consequences on the light elements abundances.   we model and analyze this process, and present the results according to various possible accretion scenarios.   we give a detailed discussion of the different ways of treating thermohaline mixing, as proposed by previous authors, and we converge on a consistent view, including the most recent numerical simulations.   we show how the observations of light elements in stars can be used as tracers of such events.
 ] background : + + + + + + + + + + +    if biology is modular then clusters, or communities, of proteins derived using only protein interaction network structure should define protein modules with similar biological roles.   we investigate the link between biological modules and network communities in yeast and its relationship to the scale at which we probe the network.    ] results : + + + + + + + +    our results demonstrate that the functional homogeneity of communities depends on the scale selected, and that almost all proteins lie in a functionally homogeneous community at some scale.   we judge functional homogeneity using a novel test and three independent characterizations of protein function, and find a high degree of overlap between these measures.   we show that a high mean clustering coefficient of a community can be used to identify those that are functionally homogeneous. by tracing the community membership of a protein through multiple scales   we demonstrate how our approach could be useful to biologists focusing on a particular protein.    [    ] conclusions : + + + + + + + + + + + +    we show that there is no one scale of interest in the community structure of the yeast protein interaction network, but we can identify the range of resolution parameters that yield the most functionally coherent communities, and predict which communities are most likely to be functionally homogeneous.    
when dealing with symmetry properties of mathematical objects, one of the fundamental questions is to determine their full automorphism group. in this paper   this question is considered in the context of even / odd permutations dichotomy. more precisely : when is it that existence of automorphisms acting as even permutations on the vertex set of a graph, called _ even automorphisms _, forces existence of automorphisms that act as odd permutations, called _   odd automorphisms_. as a first step towards resolving the above question, a complete information on existence of odd automorphisms in cubic symmetric graphs is given.
using our recently improved understanding of star cluster physics, we are now within reach of answering a number of fundamental questions in contemporary astrophysics.   star cluster physics has immediate bearing on questions ranging from the physical basis of the stellar initial mass function  do any o - type stars form in isolation?   what is the relative importance of stochastic ( random ) star formation versus competitive accretion?  to the build - up of the most massive clusters  does the cluster mass function differ in different types of galaxies?   how and why do the most massive star clusters form in small dwarf galaxies and what does that imply for the build - up of larger cluster samples? what are the main observables one could ( or should ) use to try and distinguish among the various star- and cluster - formation scenarios? newly emerging theoretical insights,   novel high - quality observational data and the advent of the next generation of observational facilities offer significant promise to reach satisfactory and robust answers to the key outstanding questions in this field.
the late - time behaviour of the einstein - dust system is well understood for homogeneous spacetimes. for the case of bianchi   i we have been able to show that the late - time behaviour of the einstein - vlasov system is well approximated by the einstein - dust system assuming that one is close to the unique stationary solution which is the attractor of the einstein - dust system.
we study an optomechanical system in which the collective density excitations ( bogoliubov modes ) of a bose einstein condensate ( bec ) is coupled to a cavity field.   we show that the optical force changes the frequency and the damping constant of the collective density excitations of the bec.   we further analyze the occurrence of normal mode splitting ( nms ) due to mixing of the fluctuations of the cavity field and the fluctuations of the condensate with finite atomic two - body interaction.   the nms is found to vanish for small values of the two - body interaction.   we further show that the density excitations of the condensate can be used to squeeze the output quantum fluctuations of the light beam.   this system may serve as an optomechanical control of quantum fluctuations using a bose einstein condensate.
statistics of article page views is useful for measuring the impact of individual articles. analyzing the temporal evolution of article page views  , we find that article page views usually decay over time after reaching a peak, especially exhibiting relaxation with nonexponentiality.   this finding suggests that relaxation in article page views resembles physical aging as frequently found in complex systems.
the lhc has started to constrain supersymmetry - breaking parameters by setting bounds on possible colored particles at the weak scale.   moreover, constraints from higgs physics, flavor physics, the anomalous magnetic moment of the muon, as well as from searches at lep and the tevatron have set additional bounds on these parameters.   renormalization group invariants ( rgis ) provide a very useful way of representing the allowed parameter space by making direct connection with the values of these parameters at the messenger scale. using a general approach, based on the pmssm parametrization of the soft supersymmetry - breaking parameters,   we analyze the current experimental constraints to determine the probability distributions for the rgis. as examples of their application  , we use these distributions to analyze the question of gaugino mass unification and to probabilistically determine the parameters of general and minimal gauge mediation with arbitrary higgs mass parameters at the messenger scale.
a long - range soliton interaction is discussed whereby two or more dark solitons interact in an inhomogeneous atomic condensate, modifying their respective dynamics via the exchange of sound waves without ever coming into direct contact.   an idealized double well geometry is shown to yield perfect energy transfer and complete periodic identity reversal of the two solitons.   two experimentally relevant geometries are analyzed which should enable the observation of this long - range interaction.   = 5000 = 1000
we consider two minimal models of active fluid droplets that exhibit complex dynamics including steady motion, deformation, rotation and oscillating motion.   first we consider a droplet with a concentration of active contractile matter adsorbed to its boundary.   we analytically predict activity driven instabilities in the concentration profile, and compare them to the dynamics we find from simulations.   secondly, we consider a droplet of active polar fluid of constant concentration. in this system   we predict, motion and deformation of the droplets in certain activity ranges due to instabilities in the polarisation field.   both these systems show spontaneous transitions to motility and deformation which resemble dynamics of the cell cytoskeleton in animal cells.
if the dynamics of an evolutionary differential equation system possess a low - dimensional, attracting, slow manifold, there are many advantages to using this manifold to perform computations for long term dynamics, locating features such as stationary points, limit cycles, or bifurcations  . approximating the slow manifold, however, may be computationally as challenging as the original problem.   if the system is defined by a legacy simulation code or a microscopic simulator, it may be impossible to perform the manipulations needed to directly approximate the slow manifold. in this paper   we demonstrate that with the knowledge only of a set of `` slow '' variables that can be used to _   parameterize _ the slow manifold, we can conveniently compute, using a legacy simulator, on a nearby manifold. forward and   reverse integration, as well as the location of fixed points are illustrated for a discretization of the chafee - infante pde for parameter values for which an inertial manifold is known to exist, and can be used to validate the computational results.   * keywords * differential equations, inertial manifolds, stiff equations
we show that, nonlinear optical processes of nanoparticles can be controlled by the presence of interactions with a molecule or a quantum dot. by choosing the appropriate level spacing for the quantum emitter  , one can either suppress or enhance the nonlinear frequency conversion.   we reveal the underlying mechanism for this effect, which is already observed in recent experiments : ( i ) suppression occurs simply because transparency induced by fano resonance does not allow an excitation at the converted frequency.   ( ii ) enhancement emerges since nonlinear process can be brought to resonance.   path interference effect cancels the nonresonant frequency terms.   we demonstrate the underlying physics using a simplified model, and we show that the predictions of the model are in good agreement with the 3-dimensional boundary element method ( mnpbem toolbox ) simulations. here  , we consider the second harmonic generation in a plasmonic converter as an example to demonstrate the control mechanism.   the phenomenon is the semi - classical analog of nonlinearity enhancement via electromagnetically induced transparency.
we study the evolution of gravitational waves through the preheating era that follows inflation.   the oscillating inflaton drives parametric resonant growth of scalar field fluctuations, and although super - hubble tensor modes are not strongly amplified, they do carry an imprint of preheating.   this is clearly seen in the weyl tensor, which provides a covariant description of gravitational waves.
there is a strong connection between the formation of a disk galaxy and the properties of the interstellar medium ( ism ).   theoretical work has typically either focused on the cosmological buildup of a galaxy with a relatively crude model for the gas physics, or examined local processes in the ism and ignored the global evolution of the galaxy itself.   here, i briefly review what has been learned from both of these approaches, and what can be done to bridge the gap between them.   i argue that cosmological simulations need to learn from observational and theoretical work on local ism properties and adopt more sophisticated models for the processes that they can not resolve.   since the ism is still incompletely understood, there are a number of reasonable approaches for these  subgrid " models, and i will discuss the strengths and limitations of each.
the influence of short - range correlations on the momentum and energy distribution of nucleons in nuclei is evaluated assuming a realistic meson - exchange potential for the nucleon - nucleon interaction. using the green - function approach   the calculations are performed directly for the finite nucleus @xmath0o avoiding the local density approximation and its reference to studies of infinite nuclear matter.   the nucleon - nucleon correlations induced by the short - range and tensor components of the interaction yield an enhancement of the momentum distribution at high momenta as compared to the hartree - fock description.   these high - momentum components should be observed mainly in nucleon knockout reactions like @xmath1 leaving the final nucleus in a state of high excitation energy.   our analysis also demonstrates that non - negligible contributions to the momentum distribution should be found in partial waves which are unoccupied in the simple shell - model.   the treatment of correlations beyond the brueckner - hartree - fock approximation also yields an improvement for the calculated ground - state properties.
this is the second in a series of papers reporting on a large reverberation mapping ( rm ) campaign to measure black hole ( bh ) mass in high accretion rate active galactic nuclei ( agns ).   the goal is to identify super - eddington accreting massive black holes ( seambhs ) and to use their unique properties to construct a new method for measuring cosmological distances.   based on theoretical models, the saturated bolometric luminosity of such sources is proportional to the bh mass which can be used to obtain their distance. here   we report on five new rm measurements and show that in four of the cases we can measure the bh mass and three of these sources are seambhs. together with the three sources from our earlier work  , we now have six new sources of this type.   we use a novel method based on a minimal radiation efficiency to identify nine additional seambhs from earlier rm - based mass measurements.   we use a bayesian analysis to determine the parameters of the new distance expression, and the method uncertainties, from the observed properties of the objects in the sample.   the ratio of the newly measured distances to the standard cosmological ones has a mean scatter of 0.14 dex, indicating that seambhs can be use as cosmological distance probes. with their high luminosity, long period of activity and large numbers at high redshifts, seambhs have a potential to extend the cosmic distance ladder beyond the range now explored by type ia supernovae.
solving the kohn - sham eigenvalue problem constitutes the most computationally expensive part in self - consistent _ density functional theory _ ( dft ) calculations. in a previous paper  , we have proposed a nonlinear chebyshev - filtered subspace iteration method, which avoids computing explicit eigenvectors except at the first scf iteration.   the method may be viewed as an approach to solve the original nonlinear kohn - sham equation by a nonlinear subspace iteration technique, without emphasizing the intermediate linearized kohn - sham eigenvalue problems.   it reaches self - consistency within a similar number of scf iterations as eigensolver - based approaches.   however, replacing the standard diagonalization at each scf iteration by a chebyshev subspace filtering step results in a significant speedup over methods based on standard dagonalization. here, we discuss an approach for implementing this method in multi - processor, parallel environment.   numerical results are presented to show that the method enables to perform a class of highly challenging dft calculations that were not feasible before.
we report the discovery of possible infrared counterparts to sgr 1806 - 20.   we use archival _ chandra _ observations to determine the location of sgr 1806 - 20 to @xmath0 accuracy.   we then locate 2 infrared objects within this error circle in k - band ( @xmath1 m ) images of this field.   based on the x - ray absorption towards sgr 1806 - 20 and the extinction towards the nearby star cluster, we discuss the likelihood of association for the possible counterparts, and the implications for sgr 1806 - 20 s physical properties and origins.
field theories invariant to conformal transformations are a very important class of models. besides their theoretical significance due to their large symmetry group, they are important also from the practical point of view. for instance   the kinematic part of the standard model lagrangian also shows conformal invariance. in the usual approach  , a field theory is called conformal invariant whenever its field equations or its action is invariant to the conformal transformations of the spacetime metric tensor along with corresponding transformation of the field quantities. for this, an action of the conformal transformations on the fields needs to be specified a priori, and conformal invariance only makes sense along with this group action.   it this paper we introduce a simple new method of generating field theories in terms of their lagrangian, without a priori specifying the action of the conformal group on the fields.   the interesting aspect of this method is that it does not to refer to a spacetime metric tensor a priori, and therefore becomes particularly useful when searching for theories where the spacetime metric tensor is an emergent quantity, not a fundamental field.   _ keywords _ : conformal invariance, non - metric formulation, lagrangian, palatini
we investigate the simileptonic ozi - forbidden annihilation decays @xmath0 for @xmath1 in the perturbative qcd, and carry out a precise calculation without any approximation for the one - loop contributions, which involves integrals of 4- and 5-point loop functions.   our results show that the branching ratios of decays @xmath2, @xmath3 and @xmath4, turn out to be of orders @xmath5, @xmath6 and @xmath7, respectively, which could be observable in the future experiments at the lhc.
we test models for the evolution of neutron star ( ns ) magnetic fields ( b ). our model for the evolution of the ns spin   is taken from an analysis of pulsar timing noise presented by hobbs et al.   ( 2010 ).   we first test the standard model of a pulsar s magnetosphere in which b does not change with time and magnetic dipole radiation is assumed to dominate the pulsar s spin - down.   we find this model fails to predict both the magnitudes and signs of the second derivatives of the spin frequencies ( @xmath0 ).   we then construct a phenomenological model of the evolution of @xmath1, which contains a long term decay ( ltd ) modulated by short term oscillations ( sto ) ; a pulsar s spin is thus modified by its b - evolution.   we find that an exponential ltd is not favored by the observed statistical properties of @xmath0 for young pulsars and fails to explain the fact that @xmath0 is negative for roughly half of the old pulsars.   a simple power - law ltd can explain all the observed statistical properties of @xmath0.   finally we discuss some physical implications of our results to models of the @xmath1-decay of nss and suggest reliable determination of the true ages of many young nss is needed, in order to constrain further the physical mechanisms of their @xmath1-decay.   our model can be further tested with the measured evolutions of @xmath2 and @xmath0 for an individual pulsar ; the decay index, oscillation amplitude and period can also be determined this way for the pulsar.
coherent stochastic resonance is explained in terms of first passage time density functions. scaling relation between first passage time density functions at resonance for different lengths of the medium   is obtained. a formula for first passage time density function at resonance   is derived in terms of two universal functions, which demonstrates the universal feature of coherent stochastic resonance.   a simple approximate expression for first passage time density function at resonance is proposed which is shown to explain the behavior at resonance fairly accurately.   key words : synchronization, coherent stochastic resonance, first passage time density functions
we study a minimal shell model for the advection of a passive scalar by a gaussian time correlated velocity field. the anomalous scaling properties of the white noise limit are studied analytically.   the effect of the time correlations are investigated using perturbation theory around the white noise limit and non - perturbatively by numerical integration.   the time correlation of the velocity field is seen to enhance the intermittency of the passive scalar.
we investigate collective modes in three dimensional ( 3d ) gapless multi - weyl semimetals with anisotropic energy band dispersions ( i.e., @xmath0 with a positive integer @xmath1 ). for comparison  , we also consider the gapless semimetals with the isotropic band dispersions ( i.e. @xmath2 ).   we calculate analytically long - wavelength plasma frequencies incorporating interband transitions and chiral properties of carriers. for both the isotropic and anisotropic cases,   we find that interband transitions and chirality lead to the depolarization shift of plasma frequencies. for the isotropic parabolic band dispersion the long - wavelength plasmons do not decay via landau damping, while for the higher - order band dispersions the long - wavelength plasmons experience damping below a critical density. for systems with the anisotropic dispersion the density dependence of the long - wavelength plasma frequency along the direction of non - linear dispersion behaves like that of the isotropic linear band model, while along the direction of linear dispersion it behaves like that of the isotropic non - linear model.   plasmons along both directions remain undamped over a broad range of densities due to the chirality induced depolarization shift.   our results provide a comprehensive picture of how band dispersion and chirality affect plasmon behaviors in 3d gapless chiral systems with the arbitrary band dispersion.
very recently quasi two - dimensional ( 2d ) systems made of attractive fermionic alkali - metal atoms with a widely tunable interaction due to fano - feshbach resonances have been realized. in this way   it has been achieved the 2d crossover from the bardeen - cooper - schrieffer regime of weakly - interacting cooper pairs to the bose - einstein condensate regime strongly bound dimers.   these experiments pave the way to the investigation of 2d strongly - interacting attractive fermions during the berezinskii - kosterlitz - thouless ( bkt ) transition from a low - temperature superfluid phase characterized by quasi - condensation to a high - temperature normal phase, where vortex proliferation driven by quantum and thermal fluctuations completely destroys superfluidity. in this paper   we discuss our preliminar theoretical results on the behavior of the bkt critical temperature across the crossover.   our microscopic calculations are based on functional integration taking into account renormalized gaussian fluctuations and the crucial 2d effect of vortex - antivortex unbinding.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
a theory of the anomalous hall conductivity based on the properties of single site orbitals is presented.   effect of the finite electron life time is modeled by energy fluctuations of atomic - like orbitals.   transition from the ideal bloch system for which the conductivity is determined by the berry phase curvatures to the case of strong disorder for which the conductivity becomes dependent on the relaxation time is analyzed.   presented tight - binding model gives by the unified way experimentally observed qualitative features of the anomalous conductivity in the so called good metal regime and that called as bad metal or hopping regime.
the dominant component of the ( 100 mev - 50 gev ) grb emission detected by lat starts with a delay relative to the prompt soft ( sub - mev ) gamma - rays and lasts long after the soft component fades.   this has lead to the intriguing suggestion that this high energy emission is generated via synchrotron emission of relativistic electrons accelerated by the external shock.   moreover, the limits on the mev afterglow emission lead to the suggestion that, at least in bright gev bursts the field is not amplified beyond compression in the shock. we show here that considerations of confinement ( within the decelerating shock ), efficiency and cooling of the emitting electrons constrain, within this model, the magnetic fields that arise in both the upstream ( circum burst ) and downstream ( ejecta ) regions, allowing us to obtain a direct handle on their values. the well known limit on the maximal synchrotron emission, when combined with the blast wave evolution, implies that late photons ( arriving more than @xmath0 100 s after the burst ) with energies higher than @xmath110gev do not arise naturally from external shock synchrotron and almost certainly have a different origin.   finally, even a modest seed flux ( a few mjy ) at ir - optical would quench, via inverse compton cooling, the gev emission unless the magnetic field is significantly amplified behind the shock.   an observation of a burst with simultaneous ir - optical and gev emission will rule out this model.
we explore observational constraints on a cosmological brane - world scenario in which the bulk is not empty.   rather, exchange of mass - energy between the bulk and the bane is allowed.   the evolution of matter fields to an observer on the brane is then modified due to new terms in the energy momentum tensor describing this exchange.   we investigate the constraints from various cosmological observations on the flow of matter from the bulk into the brane.   interestingly, we show that it is possible to have a @xmath0 cosmology to an observer in the brane which satisfies standard cosmological constraints including the cmb temperature fluctuations, type ia supernovae at high redshift, and the matter power spectrum.   this model even accounts for the observed suppression of the cmb power spectrum at low multipoles. in this cosmology  , the observed cosmic acceleration is attributable to the flow of matter from the bulk to the brane.   a peculiar aspect of this cosmology is that the present dark - matter content of the universe may be significantly larger than that of a @xmath1cdm cosmology.   its influence, however, is offset by the dark - radiation term.   possible additional observational tests of this new cosmological paradigm are suggested.
we present theoretical and experimental evidence of a universal mechanism through which temporal cavity solitons of externally - driven, passive, kerr resonators can form robust long - range bound states. these bound states, sometime also referred to as multi - soliton states or soliton crystals in microresonators, require perturbations to the strict lugiato - lefever mean field description of temporal cavity solitons. binding occurs when the perturbation excites a narrowband resonance in the soliton spectrum, which gives long oscillatory tails to the solitons.   those tails can then interlock for a discrete set of temporal separations between the solitons.   the universality of this mechanism is demonstrated in fiber ring cavities by providing experimental observations of long - range bound states ensuing from three different perturbations : third - order dispersion ( dispersive wave generation ), the periodic nature of the cavity ( kelly sidebands ), and the random birefringence of the resonator.   sub - picosecond resolution of bound state separations and their dynamics are obtained by using the dispersive fourier transform technique.   good agreement with theoretical models, including a new vector mean - field model, is also reported.
this paper gives results for the spectrum, all allowed e1 radiative partial widths ( and some important m1 widths ) and all open - charm strong decay amplitudes of all 40 @xmath0 states expected up to the mass of the 4s multiplet, just above 4.4  gev.   the spectrum and radiative widths are evaluated using two models, the relativized godfrey - isgur model and a nonrelativistic potential model.   the electromagnetic transitions are evaluated using coulomb plus linear plus smeared hyperfine wavefunctions, both in a nonrelativistic potential model and in the godfrey - isgur model.   the open - flavor strong decay amplitudes are determined assuming harmonic oscillator wavefunctions and the @xmath1p@xmath2 decay model.   this work is intended to motivate future experimental studies of higher - mass charmonia, and may be useful for the analysis of high - statistics data sets to be accumulated by the bes, cleo and gsi facilities.   h l p  s
this investigation is aimed at clarifying the nature of the interstellar gas seen in absorption against bright o and b stars. towards this end   we have obtained for the first time hi absorption spectra towards radio sources very close to the lines of sight towards 25 bright stars previously studied. in this paper   we describe the selection criteria, the details regarding our observations, and finally present the absorption spectra. in the accompanying paper we analyse the results and draw conclusions.       ism : clouds, ism : structure, radio lines : ism
we discuss two phenomenological descriptions of low - current transport in bilayer quantum hall system with exciton condensates, one based on a landauer - buttiker description of andreev scattering at contacts to coherent bilayers and one based on a simplified single - parameter _ p - ology _ description of the weak to strong interlayer coupling crossover.   the andreev scattering phenomenology in intended to apply when the condensate is well developed and is used to predict current - voltage relationships for a variety of two contact geometries.   we also apply this formalism to circumstances in which the tunnel current exceeds its critical value and the condensate is time - dependent.   the _   p - ology _ approach is used to establish the universal development of large longitudinal drags, even in homogenous coherent samples, as the condensate weakens and the hall drag is reduced.
attribute reduction is a basic issue in knowledge representation and data mining.   rough sets provide a theoretical foundation for the issue.   matroids generalized from matrices have been widely used in many fields, particularly greedy algorithm design, which plays an important role in attribute reduction.   therefore, it is meaningful to combine matroids with rough sets to solve the optimization problems. in this paper, we introduce an existing algebraic structure called dependence space to study the reduction problem in terms of matroids.   first, a dependence space of matroids is constructed.   second, the characterizations for the space such as consistent sets and reducts are studied through matroids.   finally, we investigate matroids by the means of the space and present two expressions for their bases. in a word,   this paper provides new approaches to study attribute reduction.   rough set, matroid, dependence space
we carry out quantum inelastic scattering calculations of collisions of rb atoms with inverting nh@xmath0 and nd@xmath0 molecules in the energy range between 0 and 100 @xmath1, which are important for experiments using velocity - controlled molecular beams to probe scattering resonances.   we focus on molecules initially in the upper level of the ammonia inversion doublet for @xmath2, which is low - field - seeking and can be controlled in a stark decelerator.   we calculate the integral elastic and state - to - state inelastic cross sections in the coupled states approximation.   we demonstrate the presence of both shape and feshbach resonances in the elastic and inelastic cross sections at low collision energies and discuss their origin in terms of the bound states of rb   nd@xmath0 complex.   we also consider elastic and inelastic cross sections in the ultracold regime, using close - coupling calculations, in order to assess the viability of sympathetic cooling of nd@xmath0 by rb. the inelastic cross section for relaxation to the lower level of the inversion doublet is smaller than expected for such a strongly coupled system, but is still likely to be too large to allow sympathetic cooling for nd@xmath0 in low - field - seeking states.   however, there is a good prospect that sympathetic cooling will be possible for molecules in high - field - seeking states, even when the collision partner is a magnetically trapped atom in a low - field - seeking state.
deep multi - color galaxy surveys with photometric redshifts will provide a large number of two - point correlation observables : galaxy - galaxy angular correlations, galaxy - shear cross correlations, and shear - shear correlations between all redshifts.   these observables can potentially enable a joint determination of the dark energy dependent evolution of the dark matter and distances as well as the relationship between galaxies and dark matter halos. with recent cmb determinations of the initial power spectrum, a measurement of the mass clustering at even a _   single _ redshift will constrain a well - specified combination of dark energy parameters in a flat universe ; we provide convenient fitting formulae for such studies.   the combination of galaxy - shear and galaxy - galaxy correlations can determine this amplitude at _ multiple _ redshifts.   we illustrate this ability in a description of the galaxy clustering with 5 free functions of redshift which can be fitted from the data.   the galaxy modeling is based on a mapping onto halos of the same abundance that models a flux - limited selection. in this context and under a flat geometry  , a 4000 deg@xmath0 galaxy - lensing survey can achieve a _ statistical _ precision of @xmath1 for the dark energy density, @xmath2 and @xmath3 for its equation of state and evolution, evaluated at dark energy matter equality @xmath4, as well as constraints on the 5 halo functions out to @xmath5.   more importantly, a joint analysis can make dark energy constraints robust against systematic errors in the shear - shear correlation and halo modeling.
we discuss recent developments in the study of primordial black holes, focussing particularly on their formation and quantum evaporation.   such studies can place important constraints on models of the early universe.   an especially interesting development has been the realization that such constraints may be severely modified if the value of the gravitational  constant " @xmath0 varies with cosmological epoch, a possibility which arises in many scenarios for the early universe.   the nature of the modification depends upon whether the value of @xmath0 near a black hole maintains the value it had at its formation epoch ( corresponding to gravitational memory ) or whether it tracks the background cosmological value.   this is still uncertain but we discuss various approaches which might help to resolve the issue.
by introducing a temporal change timescale @xmath0 for the time - dependent system hamiltonian, a general formulation of the markovian quantum master equation is given to go well beyond the adiabatic regime.   in appropriate situations, the framework is well justified even if @xmath0 is faster than the decay timescale of the bath correlation function.   an application to the dissipative landau - zener model demonstrates this general result.   the findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
previous studies suggest that the planet  forming disks around very  low  mass stars / brown dwarfs may be flatter than those around more massive stars, in contrast to model predictions of larger scale heights for gas  disks around lower  mass stars.   we conducted a statistically robust study to determine whether there is evidence for stellar  mass  dependent disk structure in planet  forming disks.   we find a statistically significant difference in the spitzer / irac color distributions of disks around very  low   mass and low  mass stars all belonging to the same star - forming region, the chamaeleon i star  forming region.   we show that self consistently calculated disk models can not fit the median spectral energy distributions ( seds ) of the two groups.   these seds can be only explained by flatter disk models, consistent with the effect of dust settling in disks.   we find that relative to the disk structure predicted for flared disks the required reduction in disk scale height is anti  correlated with the stellar mass, i.e. disks around lower  mass stars are flatter.   our results show that the initial and boundary conditions of planet formation are stellar  mass  dependent, an important finding that must be considered in planet formation models.
we consider the phase coherent transport of a quasi one - dimensional beam of bose - einstein condensed particles through a disordered potential of length @xmath0. among the possible different types of flow we identified [ t. paul, p. schlagheck, p. leboeuf and n. pavloff, phys.   rev. lett. * 98 *, 210602 ( 2007 ) ], we focus here on the supersonic stationary regime where anderson localization exists.   we generalize the diffusion formalism of dorokhov - mello - pereyra - kumar to include interaction effects.   it is shown that interactions modify the localization length and also introduce a length scale @xmath1 for the disordered region, above which most of the realizations of the random potential lead to time dependent flows.   a fokker - planck equation for the probability density of the transmission coefficient that takes this new effect into account is introduced and solved.   the theoretical predictions are verified numerically for different types of disordered potentials.   experimental scenarios for observing our predictions are discussed.
we report an analysis of the interstellar @xmath0-ray emission in the third galactic quadrant measured by the fermi large area telescope.   the window encompassing the galactic plane from longitude @xmath1 to @xmath2 has kinematically well - defined segments of the local and the perseus arms, suitable to study the cosmic - ray densities across the outer galaxy.   we measure no large gradient with galactocentric distance of the @xmath0-ray emissivities per interstellar h atom over the regions sampled in this study.   the gradient depends, however, on the optical depth correction applied to derive the h  column densities.   no significant variations are found in the interstellar spectra in the outer galaxy, indicating similar shapes of the cosmic - ray spectrum up to the perseus arm for particles with gev to tens of gev energies.   the emissivity as a function of galactocentric radius does not show a large enhancement in the spiral arms with respect to the interarm region.   the measured emissivity gradient is flatter than expectations based on a cosmic - ray propagation model using the radial distribution of supernova remnants and uniform diffusion properties. in this context, observations require a larger halo size and/or a flatter cr source distribution than usually assumed. the molecular mass calibrating ratio, @xmath3, is found to be @xmath4 in the local - arm clouds and is not significantly sensitive to the choice of h  spin temperature.   no significant variations are found for clouds in the interarm region.
it has recently been suggested that compton downscattering may give rise to the broad iron lines seen in the x - ray spectra of seyfert 1 galaxies.   this challenges the standard model in which these lines originate from the innermost regions of the black hole accretion disk with doppler shifts and gravitational redshifts giving rise to the broadened line profile. here  , we apply observational constraints to the compton downscattering model for mcg@xmath06 - 30 - 15 and ngc  3516, the two best cases to date of seyfert galaxies with relativistically broad lines.   we show that the continuum source in mcg@xmath06 - 30 - 15 required by the constrained model violates the black body limit. in the case of ngc  3516, only a very small region of parameter space   is compatible with the constraints.   hence, we conclude that the comptonization model is not a viable one for the broad line seen in these two objects.   the accretion disk model remains the best interpretation of these data.   galaxies : seyfert, galaxies : individual : mcg@xmath06 - 30 - 15, galaxies : individual : ngc  3516, line : formation, x - ray : galaxies
this letter presents a revised radiative transfer model for the infrared ( ir ) emission of active galactic nuclei ( agn ).   while current models assume that the ir is emitted from a dusty torus in the equatorial plane of the agn, spatially resolved observations indicate that the majority of the ir emission from @xmath0100pc in many agn originates from the polar region, contradicting classical torus models.   the new model _ cat3d - wind _ builds upon the suggestion that the dusty gas around the agn consists of an inflowing disk and an outflowing wind. here  , it is demonstrated that ( 1 ) such disk+wind models cover overall a similar parameter range of observed spectral features in the ir as classical clumpy torus models, e.g. the silicate feature strengths and mid - ir spectral slopes, ( 2 ) they reproduce the @xmath1 bump observed in many type 1 agn unlike torus models, and ( 3 ) they are able to explain polar emission features seen in ir interferometry, even for type 1 agn at relatively low inclination, as demonstrated for ngc3783.   these characteristics make it possible to reconcile radiative transfer models with observations and provide further evidence of a two - component parsec - scaled dusty medium around agn : the disk gives rise to the @xmath1 near - ir component, while the wind produces the mid - ir emission.   the model seds will be made available for download.
dual agns are natural byproducts of hierarchical mergers of galaxies in the @xmath0cdm cosmogony.   recent observations have shown that only a small fraction ( @xmath1 ) of agns at redshift @xmath2 are dual with kpc - scale separations, which is rather low compared to the high merger rate of galaxies. here   we construct a phenomenological model to estimate the number density of dual agns and its evolution according to the observationally - estimated major merger rates of galaxies and various scaling relations on the properties of galaxies and their central massive black holes.   we show that our model reproduces the observed frequency and separation distribution of dual agns provided that significant nuclear activities are triggered only in gas - rich progenitor galaxies with central massive black holes and only when the nuclei of these galaxies are roughly within the half - light radii of their companion galaxies. under these constraints,   the observed low dual agn frequency is consistent with the relatively high merger rate of galaxies and supports the hypothesis that major mergers lead to agn / qso activities.   we also predict that the number of kpc - scale dual agns decreases with increasing redshift and only about 0.02%0.06% of agns are dual agns with double - peaked narrow line features at redshifts of @xmath3.   future observations of high - redshift dual agns would provide a solid test for this prediction.
we study certain nonlinear continuous models of opinion formation derived from a kinetic description involving exchange of opinion between individual agents.   these models imply that the only possible final opinions are the extremal ones, and are similar to models of pure drift in magnetization.   both analytical and numerical methods allow to recover the final distribution of opinion between the two extremal ones.    nonlinear nonlocal hyperbolic equation, sociophysics, opinion formation, magnetization.   91c20 ; 82b21 ; 60k35.
the high - energy qcd factorization for deep inelastic scattering and for proton - nucleus collisions using wilson line formalism and factorization in rapidity is discussed.   we show that in dis the factorization in rapidity reduces to the @xmath0-factorization when the 2-gluon approximation is applied, provided that the composite wilson line operator is used in the high - energy operator product expansion.   we then show that the inclusive forward cross - section in proton - nucleus collisions factorizes in parton distribution functions, fragmentation functions and dipole gluon distribution function at one - loop level.
the thorup - zwick ( tz ) routing scheme is the first generic stretch-3 routing scheme delivering a nearly optimal local memory upper bound. using both direct analysis and simulation  , we calculate the stretch distribution of this routing scheme on random graphs with power - law node degree distributions, @xmath0.   we find that the average stretch is very low and virtually independent of @xmath1.   in particular, for the internet interdomain graph, @xmath2, the average stretch is around @xmath3, with up to 70% of paths being shortest  . as the network grows, the average stretch slowly decreases.   the routing table is very small, too.   it is well below its upper bounds, and its size is around @xmath4 records for @xmath5-node networks.   furthermore, we find that both the average shortest path length ( i.e.  distance ) @xmath6 and width of the distance distribution @xmath7 observed in the real internet inter - as graph have values that are very close to the minimums of the average stretch in the @xmath6- and @xmath7-directions.   this leads us to the discovery of a unique critical quasi - stationary point of the average tz stretch as a function of @xmath6 and @xmath7.   the internet distance distribution is located in a close neighborhood of this point.   this observation suggests the analytical structure of the average stretch function may be an indirect indicator of some hidden optimization criteria influencing the internet s interdomain topology evolution.
the temperature dependence of the thermodynamic potential of quantum chromodynamics ( qcd ), the specific heat, and the quark effective mass are calculated for imbalanced quark matter in the limit of a large number of quark flavors ( large-@xmath0 ), which corresponds to the random phase approximation.   also a generalization of the relativistic landau effective - mass relation in the imbalanced case is given, which is then applied to this thermodynamic potential.
optically detected cyclotron resonance of two - dimensional electrons has been studied in nominally undoped cdte/(cd, mn)te quantum wells.   the enhancement of carrier quantum confinement results in an increase of the electron cyclotron mass from 0.099@xmath0 to 0.112@xmath0 with well width decreasing from 30 down to 3.6  nm.   model calculations of the electron effective mass have been performed for this material system and good agreement with experimental data is achieved for an electron - phonon coupling constant @xmath1=0.32.
loyal buyer - seller relationships can arise by design, e.g. when a seller tailors a product to a specific market niche to accomplish the best possible returns, and buyers respond to the dedicated efforts the seller makes to meet their needs.   we ask whether it is possible, instead, for loyalty to arise spontaneously, and in particular as a consequence of repeated interaction and co - adaptation among the agents in a market.   we devise a stylized model of double auction markets and adaptive traders that incorporates these features.   traders choose where to trade ( which market ) and how to trade ( to buy or to sell ) based on their previous experience.   we find that when the typical scale of market returns ( or, at fixed scale of returns, the intensity of choice ) become higher than some threshold, the preferred state of the system is segregated : both buyers and sellers are segmented into subgroups that are persistently loyal to one market over another.   we characterize the segregated state analytically in the limit of large markets : it is stabilized by some agents acting cooperatively to enable trade, and provides higher rewards than its unsegregated counterpart both for individual traders and the population as a whole.
in this paper we perform an assessment of the 2880 earth impact risk for asteroid ( 29075 ) 1950 da. to obtain reliable predictions we analyze the contribution of the observational dataset and the astrometric treatment, the numerical error in the long - term integration, and the different accelerations acting on the asteroid.   the main source of uncertainty is the yarkovsky effect, which we statistically model starting from 1950 da s available physical characterization, astrometry, and dynamical properties. before the realease of 2012 radar data, this modeling suggests that 1950 da has 99% likelihood of being a retrograde rotator. by using a 7-dimensional monte carlo sampling we map 1950 da s uncertainty region to the 2880 close approach @xmath0-plane and   find a @xmath1 impact probability. with the recently released 2012 radar observations,   the direct rotation is definetly ruled out and the impact probability decreases to @xmath2.   asteroids, dynamics, celestial mechanics, near - earth objects, orbit determination
in this paper we investigate a multi - source ldpc scheme for a gaussian relay system, where @xmath0 sources communicate with the destination under the help of a single relay ( @xmath1 system ). since various distributed ldpc schemes in the cooperative single - source system, e.g. bilayer ldpc  @xcite and bilayer multi - edge type ldpc ( bmet - ldpc )  @xcite,   have been designed to approach the shannon limit, these schemes can be applied to the @xmath1 system by the relay serving each source in a round - robin fashion.   however, such a direct application is not optimal due to the lack of potential joint processing gain. in this paper, we propose a network coded multi - edge type ldpc ( ncmet - ldpc ) scheme for the multi - source scenario. through an exit analysis  , we conclude that the ncmet - ldpc scheme achieves higher extrinsic mutual information, relative to a separate application of bmet - ldpc to each source.   our new ncmet - ldpc scheme thus achieves a higher threshold relative to existing schemes.   multi - source ldpc, network coding, network capacity, extrinsic mutual information.
experiments measuring cosmic rays above an energy of deduce the energy and mass of the primary cosmic ray particles from air - shower simulations. we investigate the importance of hadronic interactions at low and high energies on the distributions of muons and electrons in showers on ground. in air shower simulation programs, hadronic interactions below an energy threshold in the range from to   are simulated by low energy interaction models, like fluka or gheisha, and above that energy by high energy interaction models, e.g.  sibyll or qgjsjet.   we find that the impact on shower development obtained by switching the transition energy from to is comparable to the difference obtained by switching between fluka and gheisha.
a spectrogram of a ship wake is a heat map that visualises the time - dependent frequency spectrum of surface height measurements taken at a single point as the ship travels by.   spectrograms are easy to compute and, if properly interpreted, have the potential to provide crucial information about various properties of the ship in question. here   we use geometrical arguments and analysis of an idealised mathematical model to identify features of spectrograms, concentrating on the effects of a finite - depth channel.   our results depend heavily on whether the flow regime is subcritical or supercritical. to support our theoretical predictions, we compare with data taken from experiments conducted in a model test basin using a variety of realistic ship hulls.   finally, we note that vessels with a high aspect ratio appear to produce spectrogram data that contains periodic patterns.   we can reproduce this behaviour in a mathematical model by using a so - called two - point wavemaker.   ship wakes ; spectrograms ; shallow water ; mathematical model ; interference effects
this paper describes a naive - bayesian predictive model for 2016 u.s.   presidential election based on twitter data.   we use 33,708 tweets gathered since december 16, 2015 until february 29, 2016.   we introduce a simpler data preprocessing method to label the data and train the model.   the model achieves 95.8% accuracy on _ 10-fold cross validation _ and predicts ted cruz and bernie sanders as republican and democratic nominee respectively.   it achieves a comparable result to those in its competitor methods.
we analyze the scattering and bound state physics of a pair of atoms in a one - dimensional optical lattice interacting via a narrow feshbach resonance.   the lattice provides a structured continuum allowing for the existence of bound dimer states both below and above the continuum bands, with pairs above the continuum stabilized by either repulsive interactions or their center of mass motion. inside the band the feshbach coupling to a closed channel   bound state leads to a fano resonance profile for the transmission, which may be mapped out by rf- or photodissociative spectroscopy.   we generalize the scattering length concept to the one - dimensional lattice, where a scattering length may be defined at both the lower and the upper continuum thresholds. as a function of the applied magnetic field the scattering length at   either band edge exhibits the usual feshbach divergence when a bound state enters or exits the continuum. near the scattering length divergences the binding energy and wavefunction of the weakly bound dimer state acquires a universal form reminiscent of those of free - space feshbach molecules.   we give numerical examples of our analytic results for a specific feshbach resonance, which has been studied experimentally.
this article presents our procedure to measure the quantum state of a dc squid within a few nanoseconds, using an adiabatic dc flux pulse.   detection of the ground state is governed by standard macroscopic quantum theory ( mqt ), with a small correction due to residual noise in the bias current. in the two level limit, where the squid constitutes a phase qubit,   an observed contrast of 0.54 indicates a significant loss in contrast compared to the mqt prediction.   it is attributed to spurious depolarization ( loss of excited state occupancy ) during the leading edge of the adiabatic flux measurement pulse.   we give a simple phenomenological relaxation model which is able to predict the observed contrast of multilevel rabi oscillations for various microwave amplitudes.
we present numerical solution of the chlorine dioxide - iodine - malonic acid reaction - diffusion system in two dimensions in a boundary - fed system using a realistic model.   the bifurcation diagram for the transition from non - symmetry breaking structures along boundary feed gradients to transverse symmetry - breaking patterns in a single layer is numerically determined.   we find this transition to be discontinuous.   we make connection with earlier results and discuss prospects for future work.     
the area of stable motion for fictitious trojan asteroids around uranus equilateral equilibrium points is investigated with respect to the inclination of the asteroid s orbit to determine the size of the regions and their shape.   for this task we used the results of extensive numerical integrations of orbits for a grid of initial conditions around the points @xmath0 and @xmath1, and analyzed the stability of the individual orbits.   our basic dynamical model was the outer solar system ( jupiter, saturn, uranus and neptune ).   we integrated the equations of motion of fictitious trojans in the vicinity of the stable equilibrium points for selected orbits up to the age of the solar system of @xmath2 years.   one experiment has been undertaken for cuts through the lagrange points for fixed values of the inclinations, while the semimajor axes were varied.   the extension of the stable region with respect to the initial semimajor axis lies between @xmath3 au but depends on the initial inclination. in another   run the inclination of the asteroids orbit was varied in the range @xmath4 and the semimajor axes were fixed.   it turned out that only four windows of stable orbits survive : these are the orbits for the initial inclinations @xmath5, @xmath6, @xmath7 and @xmath8.   we postulate the existence of at least some trojans around the uranus lagrange points for the stability window at small and also high inclinations.
this is a follow - up to our earlier work on the energies and radial distributions of heavy - light mesons.   the heavy quark is taken to be static ( infinitely heavy ) and the light quark has a mass about that of the strange quark.   we now concentrate on the energies of the excited states with higher angular momentum and with a radial node.   a new improvement is the use of hypercubic blocking in the time direction.   the calculation is carried out with dynamical fermions on a @xmath0 lattice with a lattice spacing @xmath1  fm generated using a non - perturbatively improved clover action. in nature   the closest equivalent of this heavy - light system is the @xmath2 meson, which allows us to compare our lattice calculations to experimental results ( where available ) or to give a prediction where the excited states, particularly p - wave states, should lie.   we pay special attention to the spin - orbit splitting, to see which one of the states ( for a given angular momentum l ) has the lower energy.   an attempt is made to understand these results in terms of the dirac equation.
in this letter, we focus on the performance of a worst - case mobile user ( mu ) in the downlink cellular network. we derive the coverage probability and the spectral efficiency of the worst - case mu using stochastic geometry. through analytical and numerical results, we draw out interesting insights that the coverage probability and the spectral efficiency of the worst - case mu decrease down to 23% and 19% of those of a typical mu, respectively. by applying a coordinated scheduling ( cs ) scheme,   we also investigate how much the performance of the worst - case mu is improved.   cellular systems, sinr, worst - case performance, stochastic geometry, coordinated scheduling, coverage probability.
the continued observations of sw j1644 + 57 in x - ray and radio bands accumulated a rich data set to study the relativistic jet launched in this tidal disruption event.   the x - ray light curve of sw j1644 + 57 from 5 - 30 days presents two kinds of quasi - periodic variations : a 200 second quasi - periodic oscillation ( qpo ) and a 2.7-day quasi - periodic variation.   the latter has been interpreted by a precessing jet launched near the bardeen - petterson radius of a warped disk. here   we suggest that the @xmath0 200s qpo could be associated with a second, narrower jet sweeping the observer line - of - sight periodically, which is launched from a spinning black hole in the misaligned direction with respect to the black hole s angular momentum.   in addition, we show that this two - component jet model can interpret the radio light curve of the event, especially the re - brightening feature starting @xmath1 days after the trigger. from the data we infer that inner jet may have a lorentz factor of @xmath2 and a kinetic energy of @xmath3, while the outer jet may have a lorentz factor of @xmath4 and a kinetic energy of @xmath5.
we present a study of diffusion enhancement of underdamped brownian particles in 1d symmetric space - periodic potential due to external symmetric time - periodic forcing with zero mean.   we show that the diffusivity can be enhanced by many orders of magnitude at appropriate choice of the forcing amplitude and frequency.   the diffusivity demonstrates tad, abnormal ( decreasing ) temperature dependence at forcing amplitudes exceeding certain value. at any fixed forcing frequency @xmath0 normal temperature dependence of the diffusivity   is restored at low enough temperatures, @xmath1  in contrast with the problem with constant external forcing. at fixed temperature at small forcing frequency   the diffusivity either slowly decreases with @xmath0, or ( at stronger forcing ) goes through a maximum near @xmath2, reciprocal superdiffusion stage duration. at high frequencies, between @xmath2 and a fraction of the oscillation frequency at the potential minimum  , the diffusivity is shown to decrease with @xmath0 according to a power law, with exponent related to the transient superdiffusion exponent.   this behavior is found similar for the cases of sinusoidal in time and piecewise constant periodic ( `` square '' ) forcing.
the hybrid halide perovskite ch@xmath0nh@xmath0pbi@xmath0 has enabled solar cells to reach an efficiency of about 18%, demonstrating a pace for improvements with no precedents in the solar energy arena. despite such explosive progress, the microscopic origin behind the success of such material is still debated, with the role played by the organic cations in the light - harvesting process remaining unclear. here   van - der - waals - corrected density functional theory calculations reveal that the orientation of the organic molecules plays a fundamental role in determining the material electronic properties.   for instance, if ch@xmath0nh@xmath0 orients along a ( 011)-like direction, the pbi@xmath1 octahedral cage will distort and the band gap will become indirect.   our results suggest that molecular rotations, with the consequent dynamical change of the band structure, might be at the origin of the slow carrier recombination and the superior conversion efficiency of ch@xmath0nh@xmath0pbi@xmath0.
we overview a series of recent works addressing numerical simulations of partial differential equations in the presence of some elements of randomness.   the specific equations manipulated are linear elliptic, and arise in the context of multiscale problems, but the purpose is more general. on a set of prototypical situations, we investigate two critical issues present in many settings : variance reduction techniques to obtain sufficiently accurate results at a limited computational cost when solving pdes with random coefficients, and finite element techniques that are sufficiently flexible to carry over to geometries with random fluctuations  . some elements of theoretical analysis and numerical analysis are briefly mentioned.   numerical experiments, although simple, provide convincing evidence of the efficiency of the approaches.
we study discrete conjugate nets whose laplace sequence is of period four.   corresponding points of opposite nets in this cyclic sequence have equal osculating planes in different net directions, that is, they correspond in an asymptotic transformation. we show that this implies that the connecting lines of corresponding points form a discrete w - congruence.   we derive some properties of discrete laplace cycles of period four and describe two explicit methods for their construction.   msc 2010 : 53a20 ( primary ), 51a20, 53a25.   keywords : discrete conjugate net, laplace transform, asymptotic transform, discrete w - congruence, discrete projective differential geometry.
out of @xmath0 lithium - rich rosat counterparts, which are presumed to be low - mass pre - main sequence stars, 21 stars have been observed by hipparcos.   we study their parallaxes, proper motions, and photometric data. for 7 out of 10 taurus and lupus stars in our sample, proper motions and parallaxes   are not inconsistent with membership to these associations, while most of the stars in chamaeleon and scorpius appear to be young foreground stars.   combined with ground based photometry and spectroscopy, hipparcos parallaxes allow us to place 15 stars on an h - r diagram.   all these 15 stars are indeed pre - main sequence stars with ages from 1 to 15 myr.   only two of the stars are located on the hayashi - tracks, whereas the other 13 are post - ttauri stars located on radiative tracks.   although this sample is admittedly small, containing only @xmath1 of the total sample of lithium - rich rosat counterparts, it does not confirm recent predictions by other authors : we find no stars in the age range from 20 to 100 myr.   the foreground pre - main sequence stars may have been ejected towards us, or they belong to the gould belt system, a plane filled with young stars.   = 2.5 cm
xrf  030723 is the first x - ray flash ( xrf ) to show in its optical light curve ( lc ) a bump that has been interpreted as the signature of a supernova ( sn ). after subtracting the afterglow component from the observed optical lc of the xrf counterpart,   the properties of the putative sn are constrained by means of synthetic lcs of core - collapse sne. for the redshift range @xmath0   1, all possible models require a rather small mass of synthesized @xmath1ni, i.e., @xmath2(@xmath1ni ) @xmath3 0.01  0.3 @xmath4.   the models used to describe the energetic sne ic associated with gamma - ray bursts ( sne 1998bw and 2003dh ) are too massive for the observed lc. if the relation between ejected @xmath1ni  mass and total ejecta mass established from models of various type ic sne also holds for the putative sn in xrf  030723, the ejecta mass is constrained to be @xmath3 1  3 @xmath4 and the kinetic energy @xmath5 erg.   this corresponds to a progenitor with @xmath6.   the sn therefore appears to have properties intermediate between a normal sn  ic like sn  1994i and a more energetic object like sn  2002ap.
the universe with adiabatic matter creation is considered.   it is thought that the negative pressure caused by matter creation can play the role of a dark energy component, and drive the accelerating expansion of the universe.   using the type ia supernovae ( sne ia ) data, the observational hubble parameter data, the cosmic microwave background ( cmb ) data and the baryonic acoustic oscillation ( bao ) data, we make constraints on the cosmological parameters, assuming a spatially flat universe.   our results show that the model with matter creation is consistent with the sne ia data, while the joint constraints of all these observational data disfavor this model.   if the cosmological constant is taken into account, a traditional model without matter creation is favored by the joint observations.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
we describe a general analytic - numerical reduction scheme for evaluating any two - loop diagrams with general kinematics and general renormalizable interactions, whereby ten special functions form a complete set after tensor reduction.   we discuss the symmetrical analytic structure of these special functions in their integral representation, which allows for optimized numerical integration.   the process @xmath0 is used for illustration, for which we evaluate all the three - point, non - factorizable @xmath1 mixed electroweak - qcd graphs, which depend on the top quark mass.   the isolation of infrared singularities is detailed, and numerical results are given for all two - loop three - point graphs involved in this process.   = 14pt = 6.0 in = 8.5 in -0.25truein 0.30truein 0.30truein    epsf    ucla-00-tep-20 + um - th-00 - 09 + june 2000   * * reduction and evaluation of two - loop graphs with arbitrary masses * + adrian ghinculov@xmath2 and york - peng yao@xmath3 + _ @xmath2department of physics and astronomy, ucla, _ + _ los angeles, california 90095 - 1547, usa _ + _ @xmath3randall laboratory of physics, university of michigan, _ + _ ann arbor, michigan 48109 - 1120, usa _ + *
we consider the asymptotic consistency of maximum likelihood parameter estimation for dynamical systems observed with noise. under suitable conditions on the dynamical systems and the observations,   we show that maximum likelihood parameter estimation is consistent.   our proof involves ideas from both information theory and dynamical systems.   furthermore, we show how some well - studied properties of dynamical systems imply the general statistical properties related to maximum likelihood estimation.   finally, we exhibit classical families of dynamical systems for which maximum likelihood estimation is consistent.   examples include shifts of finite type with gibbs measures and axiom  a attractors with srb measures.   ,   ,
we report on a new equilibration scenario in relativistic heavy ion collisions, the scenario of the increasingly strongly interacting parton plasma, and the effects of this scenario on equilibration and open charm, photon and dilepton production.   the parton plasma is shown to be a very special kind of many - body system, which contains new physics concerning the approach towards equilibrium.   this is likely to be unique to the parton plasma.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    # 1eq.   (  )    # 1fig  .  
double  lepton polarization asymmetries in @xmath0 decay are calculated using a general, model independent form of the effective hamiltonian.   the sensitivities of these asymmetries to the new wilson coefficients are studied in detail.   furthermore, the correlations between averaged double  lepton polarization asymmetry and branching ratio are analyzed.   it is shown that there exist certain regions of the new wilson coefficients where new physics can be established by measuring the double  lepton polarization asymmetries only.    16.3 true cm 23.0 true cm -0.8 true in 0.00 true in    0^*0 5_5 s_s^??   o _ ^0 _    pacs numbers : 12.60.i, 13.30.a  . 13.88.+e
we have carried out electron energy - loss investigations of the lowest singlet excitons in pentacene at 20 k. our studies allow to determine the full exciton band structure in the @xmath0 reciprocal lattice plane.   the lowest singlet exciton can move coherently within this plane, and the resulting exciton dispersion is highly anisotropic.   the analysis of the energetically following ( satellite ) features indicates a strong admixture of charge transfer excitations to the exciton wave function.
detecting binary black holes in interferometer data requires an accurate knowledge of the orbital phase evolution of the system. from the point of view of data analysis one   also needs fast algorithms to compute the templates that will employed in searching for black hole binaries.   recently, there has been progress on both these fronts : on the one hand, re - summation techniques have made it possible to accelerate the convergence of poorly convergent asymptotic post - newtonian series and derive waveforms beyond the conventional adiabatic approximation.   we now have a waveform model that extends beyond the inspiral regime into the plunge phase followed by the quasi - normal mode ringing.   on the other hand, explicit fourier domain waveforms have been derived that make the generation of waveforms fast enough so as not to be a burden on the computational resources required in filtering the detector data.   these new developments should make it possible to efficiently and reliably search for black hole binaries in data from first interferometers.    _   keywords : _ gravitational waves, binary black holes, interferometric gravitational wave detectors, data analysis    _ pacs numbers : _ 04.3.0db, 04.25.nx, 04.80.nn, 95.55.ym
we study coherent transport through a semiconductor nanowire in the presence of spin - orbit coupling and zeeman splitting due to an applied magnetic field. by employing analytical and numerical techniques   we develop a theory for the josephson effect in the superconductor - semiconductor nanowire - superconductor structure.   we show that josephson current through the clean semiconductor nanowire exhibits a number of interesting features due to the interplay between the zeeman splitting and spin - orbit coupling.   we also study effect how disorder in the nanowire affects andreev bound - state energy spectrum and calculate local density of states at the junction.
we study the discrimination of multipartite quantum states by local operations and classical communication.   we derive that any optimal discrimination of quantum states spanning a two - dimensional hilbert space in which each party s space is finite dimensional is possible by local operations and one - way classical communication, regardless of the optimality criterion used and how entangled the states are.
we present the _ suzaku _  broad band observations of two agns detected by the _ swift_/bat hard x - ray ( @xmath015 kev ) survey that did not have previous x - ray data, swift j0601.98636  and swift j0138.64001.   the _ suzaku _   spectra reveals in both objects a heavily absorbed power law component with a column density of @xmath1  @xmath2 that dominates above 10 kev, and an intense reflection component with a solid angle @xmath3 from a cold, optically thick medium.   we find that these agns have an extremely small fraction of scattered light from the nucleus, @xmath4 with respect to the intrinsic power law component.   this indicates that they are buried in a very geometrically - thick torus with a small opening angle and/or have unusually small amount of gas responsible for scattering. in the former case  , the geometry of swift j0601.98636  should be nearly face - on as inferred from the small absorption for the reflection component.   the discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very compton thick agns viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard x - ray surveys.
in this paper we measure the angular power spectra @xmath0 of three high - redshift large - scale structure probes : the radio sources from the nrao vla sky survey ( nvss ), the quasar catalogue of sloan digital sky survey release six ( sdss dr6 qsos ) and the megaz - lrg ( dr7 ), the final sdss ii luminous red galaxy ( lrg ) photometric redshift survey.   we perform a global analysis of the constraints on the amplitude of primordial non - gaussianity from these angular power spectra, as well as from their cross - correlation power spectra with the cosmic microwave background ( cmb ) temperature map.   in particular, we include non - gaussianity of the type arising from single - field slow roll, multifields, curvaton ( local type ), and those which effects on the halo clustering can be described by the equilateral template ( related to higher - order derivative type non - gaussianity ) and by the enfolded template ( related to modified initial state or higher - derivative interactions ).   when combining all data sets, we obtain limits of @xmath1, @xmath2 and @xmath3 at @xmath4 confidence level for local, equilateral and enfolded templates, respectively.   furthermore, we explore the constraint on the cubic correction @xmath5 on the bias of dark matter haloes and obtain a limit of @xmath6 at 95% confidence level.
six contact binaries lacking a period analysis have been chosen to search for the presence of a third body.   the @xmath0 diagrams of these binaries were analyzed with the least - squares method by using all available times of minima.   ten new minima times, obtained from our observations, were included in the present research.   the light - time effect was adopted for the first time as the main cause for the detailed description of the long - term period changes.   third bodies were found with orbital periods from 49 up to 100  years, and eccentricities from 0.0 to 0.56 for the selected binaries. in one case ( wz  and )   a fourth - body lite variation was also applied.   the mass functions and the minimal masses of such bodies were also calculated and a possible angular separation and magnitude differences were discussed for a prospective interferometric discovery of these bodies.
we have studied the dynamics of quantum correlations such as entanglement, bell - nonlocality and quantum discord between identical as well as unidentical atoms interacting with a single - mode cavity field and subject to cavity decay.   the effect of single atom detuning, cavity decay rate and initial preparation of the atoms on the corresponding correlation measures have been investigated.   it is found that even under strong dissipation, time evolution can create high quantum discord while entanglement and bell nonlocality stay zero for an initially separable state.   quantum discord increases while entanglement decreases in a certain time period under dissipation for the initial state that both atoms are in the excited state if the qubits are identical. for some type of initial states,   cavity decay is shown to drive the system to a stationary state with high entanglement and quantum discord.
we investigate the emergence of hyperons in black - hole - forming failed supernovae, which are caused by the dynamical collapse of nonrotating massive stars.   we perform neutrino - radiation hydrodynamical simulations in general relativity adopting realistic hyperonic equation - of - state ( eos ).   attractive and repulsive cases are examined for the potential of @xmath0 hyperons.   since hyperons soften the eos, they shorten the time interval from the bounce to black hole formation, which corresponds to the duration of neutrino emission. this effect is larger for the attractive case than the repulsive case because @xmath0 hyperons appear more easily. in addition  , we investigate the impacts of pions to find that they also promotes the recollapse towards the black hole formation.
we searched for periodic and quasiperiodic signal in the prompt emission of a sample of 44 bright short gamma   ray bursts detected with _   fermi_/gbm, _ swift_/bat, and _ cgro_/batse.   the aim was to look for the observational signature of quasiperiodic jet precession which is expected from black hole   neutron star mergers, but not from double neutron star systems.   thus, this kind of search holds the key to identify the progenitor systems of short grbs and, in the wait for gravitational wave detection, represents the only direct way to constrain the progenitors.   we tailored our search to the nature of the expected signal by properly stretching the observed light curves by an increasing factor with time, after calibrating the technique on synthetic curves. in none of the grbs of our sample we found evidence for periodic or quasiperiodic signals.   in particular, for the 7 unambiguously short grbs with best s / n we obtained significant upper limits to the amplitude of the possible oscillations.   this result suggests that bh   ns systems do not dominate the population of short grb progenitors as described by the kinematic model of @xcite.
we calculate the magnetization of the two - dimensional electron gas in a short - period lateral superlattice, with the coulomb interaction included in hartree and hartree - fock approximations.   we compare the results for a finite, mesoscopic system modulated by a periodic potential, with the results for the infinite periodic system.   in addition to the expected strong exchange effects, the size of the system, the type and the strength of the lateral modulation leave their fingerprints on the magnetization.
we point out several features of the quantum hamiltonian constraints recently introduced by thiemann for euclidean gravity.   in particular we discuss the issue of the constraint algebra and of the quantum realization of the object @xmath0, which is classically the poisson bracket of two hamiltonians.   epsf.tex    cgpg-97 - 10/1 + gr - qc/9710018 +
the energy of an @xmath0gradient fluid depends on its eulerian velocity gradients of order @xmath1.   a variational principle is introduced for the dynamics of @xmath0gradient fluids and their properties are reviewed in the context of noether s theorem.   the stability properties of craik - criminale solutions for first and second gradient fluids are examined.
in helical hydromagnetic turbulence with an imposed magnetic field ( which is constant in space and time ) the magnetic helicity of the field within a periodic domain is no longer an invariant of the ideal equations. alternatively, there is a generalized magnetic helicity that is an invariant of the ideal equations.   it is shown that this quantity is not gauge invariant and that it can therefore not be used in practice. instead, the evolution equation of the magnetic helicity of the field describing the deviation from the imposed field is shown to be a useful tool.   it is demonstrated that this tool can determine steady state quenching of the alpha - effect.   a simple three - scale model is derived to describe the evolution of the magnetic helicity and to predict its sign as a function of the imposed field strength.   the results of the model agree favorably with simulations.
we have investigated some statistical properties of integrated spectra of galaxies with principal component analysis.   the projection of the spectra onto the plane defined by the first two principal components shows that normal galaxies are in a quasi - linear sequence that we call spectral sequence and is closely related to the hubble morphological sequence.   we verify that the spectral sequence is also an evolutive sequence, with galaxy spectra evolving from later to earlier spectral types. considering the close correspondence between the spectral and morphological sequences, we speculate that galaxies may evolve morphologically along the hubble sequence, from sm /   im to e. if this is the case, the first galaxies were mainly gas rich irregular objects, which evolved later along the morphological sequence as long as mergers and interactions increased their masses and developed their spheroidal components.
we present an extension of the allen - cahn / cahn - hilliard system which incorporates a geometrically linear ansatz for the elastic energy of the precipitates.   the model contains both the elastic allen - cahn system and the elastic cahn - hilliard system as special cases and accounts for the microstructures on the microscopic scale.   we prove the existence of weak solutions to the new model for a general class of energy functionals.   we then give several examples of functionals that belong to this class.   this includes the energy of geometrically linear elastic materials for @xmath0.   moreover we show this for @xmath1 in the setting of scalar - valued deformations, which corresponds to the case of anti - plane shear.   all this is based on explicit formulas for relaxed energy functionals newly derived in this article for @xmath2 and @xmath1. in these cases   we can also prove uniqueness of the weak solutions.
many natural and engineered complex networks have intricate mesoscopic organization, e.g., the clustering of the constituent nodes into several communities or modules.   often, such modularity is manifested at several different hierarchical levels, where the clusters defined at one level appear as elementary entities at the next higher level. using a simple model of a hierarchical modular network,   we show that such a topological structure gives rise to characteristic time - scale separation between dynamics occurring at different levels of the hierarchy.   this generalizes our earlier result for simple modular networks, where fast intra - modular and slow inter - modular processes were clearly distinguished. investigating the process of synchronization of oscillators in a hierarchical modular network, we show the existence of as many distinct time - scales as there are hierarchical levels in the system.   this suggests a possible functional role of such mesoscopic organization principle in natural systems, viz.  , in the dynamical separation of events occurring at different spatial scales.
we use the renormalization group method to study model e of critical dynamics in the presence of velocity fluctuations arising in accordance with the stochastic navier - stokes equation. using martin - siggia - rose theorem  , we obtain a field - theoretical model that allows a perturbative renormalization group analysis. by direct power counting and an analysis of ultraviolet divergences,   we show that the model is multiplicatively renormalizable, and we use a two - parameter expansion in @xmath0 and @xmath1 to calculate renormalization constants. here, @xmath2 is a deviation from the critical dimension four, and @xmath1 is a deviation from the kolmogorov regime.   we present the results of the one - loop approximation and part of the fixed - point structure.   we briefly discuss the possible effect of velocity fluctuations on the large - scale behavior of the model.
many observed massive star - forming @xmath0 galaxies are large disks that exhibit irregular morphologies, with @xmath1, @xmath2 clumps.   we present the largest sample to date of high - resolution cosmological sph simulations that zoom - in on the formation of individual @xmath3 galaxies in @xmath4 halos at @xmath0.   our code includes strong stellar feedback parameterized as momentum - driven galactic winds.   this model reproduces many characteristic features of this observed class of galaxies, such as their clumpy morphologies, smooth and monotonic velocity gradients, high gas fractions ( @xmath5 ) and high specific star - formation rates ( @xmath6 ). in accord with recent models, giant clumps ( @xmath7 ) form in - situ via gravitational instabilities.   however, the galactic winds are critical for their subsequent evolution.   the giant clumps we obtain are short - lived and are disrupted by wind - driven mass loss.   they do not virialise or migrate to the galaxy centers as suggested in recent work neglecting strong winds. by phenomenologically implementing the winds that are observed from high - redshift galaxies and in particular from individual clumps, our simulations reproduce well new observational constraints on clump kinematics and clump ages.   in particular, the observation that older clumps appear closer to their galaxy centers is reproduced in our simulations, as a result of inside - out formation of the disks rather than inward clump migration.
using space-, time- and phase - resolved brillouin light scattering spectroscopy we investigate the difference in phase of the two counterpropagating spin waves excited by the same microwave microstrip transducer.   these studies are performed both for backward volume magnetostatic waves and magnetostatic surface waves in an in - plane magnetized yttrium iron garnet film.   the experiments show that for the backward volume magnetostatic spin waves ( which are reciprocal and excited symmetrically in amplitude ) there is a phase difference of @xmath0 associated with the excitation process and thus the phase symmetry is distorted. on the contrary, for the magnetostatic surface spin waves ( which are non - reciprocal and unsymmetrical in amplitude ) the phase symmetry is preserved ( there is no phase difference between the two waves associated with the excitation ).   theoretical analysis confirms this effect.
the uncertainty in the absolute value of the fluorescence yield is still one of the main contributions to the total error in the reconstruction of the primary energy of ultra - energetic air showers using the fluorescence technique.   a significant number of experimental values of the fluorescence yield have been published in the last years, however reported results are given very often in different units ( photons / mev or photons / m ) and for different wavelength intervals. in this work we present a comparison of available results normalized to its value in photons / mev for the 337  nm band at 800  hpa and 293  k. the conversion of photons / m to photons / mev requires an accurate determination of the energy deposited by the electrons in the field of view of the experimental setup.   we have calculated the energy deposition for each experiment by means of a detailed monte carlo simulation including when possible the geometrical details of the particular setup.   our predictions on deposited energy, as well as on some geometrical factors, have been compared with those reported by the authors of the corresponding experiments and possible corrections to the fluorescence yields are proposed.   = 1    _ departamento de fsica atmica, molecular y nuclear, facultad de ciencias fsicas, universidad complutense de madrid, e-28040 madrid, spain _
we introduce an information heat engine that is autonomous ( i.e., without any time - dependent parameter ) but has separated measurement and feedback processes.   this model serves as a bridge between different types of information heat engines inspired by maxwell s demon ; from the original szilard - engine type systems to the autonomous demonic setups. by analyzing our model on the basis of a general framework introduced in our previous paper [ n. shiraishi and t. sagawa, phys  . rev.   e * 91 *, 012130 ( 2015 ). ]  , we clarify the role of the separation of measurement and feedback in the integral fluctuation theorems.    //
can one understand the statistics of wins and losses of baseball teams?   are their consecutive - game winning and losing streaks self - reinforcing or can they be described statistically?   we apply the bradley - terry model, which incorporates the heterogeneity of team strengths in a minimalist way, to answer these questions.   excellent agreement is found between the predictions of the bradley - terry model and the rank dependence of the average number team wins and losses in major - league baseball over the past century when the distribution of team strengths is taken to be uniformly distributed over a finite range. using this uniform strength distribution  , we also find very good agreement between model predictions and the observed distribution of consecutive - game team winning and losing streaks over the last half - century ; however, the agreement is less good for the previous half - century.   the behavior of the last half - century supports the hypothesis that long streaks are primarily statistical in origin with little self - reinforcing component.   the data further show that the past half - century of baseball has been more competitive than the preceding half - century.
the soft gamma repeater sgr 1900 + 14 was observed in pushchino observatory since 1988 december using bsa radio telescope operating at 111 mhz.   we have detected the pulsed radio emission ( shitov 1999 ) with the same 5.16 s period that was reported earlier for this object ( hurley et al.   1998 ).   the timing analysis has shown that this new radio pulsar psr j1907 + 0919 associated with sgr 1900 + 14 has a superstrong magnetic field, which is @xmath0 g, thereby confirming that it is a `` magnetar '' ( duncan & thompson 1992 ; kouveliotou et al.   1999 ).   the dispersion measure of psr j1907 + 0919 is @xmath1 which gives an estimate of the pulsar s distance as about 5.8 kpc.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we calculate the third coefficient of the lattice @xmath0 function in pure yang - mills theory.   we make use of a computer code for solving perturbation theory analytically on the lattice.   we compute the divergent integrals by using a method based on a taylor expansion of the integrand in powers of the external momenta in @xmath1 dimensions.   our results are in agreement with a previous calculation by m. lscher and p. weisz where the authors used a different technique.   we also show how this new coefficient modifies the scaling function on the lattice in both the standard and energy schemes.   in particular we show that asymptotic scaling is extremely well achieved in the energy scheme.    * the three - loop @xmath0 function in @xmath2 lattice gauge theories *    b. alls@xmath3, a. feo@xmath4 and h. panagopoulos@xmath5    _ @xmath3dipartimento di fisica delluniversit and infn, pisa, italy _    _   @xmath6scuola normale superiore, pisa, italy   _    _ @xmath5department of natural sciences, university of cyprus, _    _ p.o.   box 537, nicosia cy-1678, cyprus _
coherent diffraction imaging ( cdi ) of single molecules at atomic resolution is a major goal for the x - ray free electron lasers ( xfels ).   however, during an imaging pulse, the fast laser - induced ionization may strongly affect the recorded diffraction pattern of the irradiated sample.   the radiation tolerance of the imaged molecule should then be investigated a priori with a dedicated simulation tool.   the continuum approach is a powerful tool for modeling the evolution of irradiated large systems consisting of more than a few hundred thousand atoms.   however, this method follows the evolution of average single - particle densities, and the experimentally recorded intensities reflect the spatial two - particle correlations.   the information on these correlations is then inherently not accessible within the continuum approach. in this paper   we analyze this limitation of continuum models and discuss the applicability of continuum models for imaging studies.   we propose a formula to calculate scattered intensities ( including both elastic and inelastic scattering ) from the estimates obtained with a single - particle continuum model.   we derive this formula for systems under conditions typical for cdi studies with xfels.
we present keck / lris spectra of a candidate damped ly@xmath0 ( dla ) galaxy toward the qso 3c196 ( z@xmath1 = 0.871 ).   the dla absorption system has a redshift of z@xmath2 = 0.437, and a galaxy at 1.5@xmath3 from the qso has been identified in high resolution imaging with wfpc2/hst.   we have detected emission lines of  @xmath43727, h@xmath5,  @xmath45007, h@xmath0 and  @xmath46584 at the absorption redshift  . based on the emission lines, we have found the redshift of the galaxy to be z@xmath1 = 0.4376 @xmath6 0.0006.   the emission lines also enabled us to calculate the extinction - corrected luminosities and metallicity indicators using established indices based on line strengths of different emission lines.   these indicators suggest that the ism of the dla galaxy has a high metallicity comparable to or perhaps twice as much as solar ( e.g. 12 + @xmath7(o / h ) = 8.98 @xmath6 0.07 ).   based on the strengths of h@xmath0 and on the reddening derived from the relative strengths of h@xmath0 and h@xmath5, the star formation rate is 4.7 @xmath6 0.8 m@xmath8 yr@xmath9.   this places the galaxy in the range of gas - rich spiral galaxies.
the tanami program has been monitoring the parsec - scale radio jets of southern @xmath0-ray bright agn with vlbi techniques simultaneously with _ fermi_/lat monitoring of their @xmath0-ray emission.   here we present the @xmath0-ray properties of the tanami sources based on an analysis of the preliminary 1-year lat source list.   we present upper limits on the @xmath0-ray flux for tanami sources not detected by lat.
we investigate the coulomb breakup of neutron rich nuclei @xmath0be and @xmath1c within a theory developed in the framework of distorted wave born approximation.   finite range effects are included by a local momentum approximation, which allows incorporation of realistic wave functions for these nuclei in our calculations.   energy and angular as well as parallel momentum distributions of the fragments emitted in the breakup of these nuclei on heavy targets have been calculated using several structure models for their ground state.   comparison with the available experimental data shows that the results are selective about the ground state wave function of the projectile.   our investigations confirm that the nuclei @xmath0be, @xmath2c and @xmath3c have a one - neutron halo structure in their ground states.   however, for @xmath4c such a structure appears to be less likely.   calculations performed within our method have also been compared with those from an adiabatic model and the results are discussed.   +   pacs numbers : 21.10.hw, 21.60.-n, 24.10.eq, 25.60.gc   ,    and    coulomb breakup, one - neutron halo nucleus, effects of projectile structure.
we consider the interacting holographic dark energy with new infrared cutoff ( involving hubble parameter and its derivative ) in non - flat universe. in this context  , we obtain the equation of state parameter which evolutes the universe from vacuum dark energy region towards quintessence region for particular values of constant parameters.   it is found that this model always remains unstable against small perturbations.   further, we establish the correspondence of this model having quintessential behavior with quintessence, tachyon, k - essence and dilaton scalar field models.   the dynamics of scalar fields and potentials indicate accelerated expansion of the universe which is consistent with the current observations.   finally, we discuss the validity of the generalized second law of thermodynamics in this scenario.   * keywords : * new holographic dark energy ; dark matter ; scalar field models ; generalized second law of thermodynamics. + * pacs : * 95.36.+x ; 95.35.+d ; 11.10.-z ; 98.80.-k.
we present the discovery of 17 low mass white dwarfs ( wds ) in short - period @xmath0 day binaries.   our sample includes four objects with remarkable @xmath1 surface gravities and orbital solutions that require them to be double degenerate binaries.   all of the lowest surface gravity wds have metal lines in their spectra implying long gravitational settling times or on - going accretion.   notably, six of the wds in our sample have binary merger times @xmath210 gyr.   four have @xmath30.9 @xmath4  companions.   if the companions are massive wds, these four binaries will evolve into stable mass transfer am cvn systems and possibly explode as underluminous supernovae. if the companions are neutron stars, then these may be milli - second pulsar binaries.   these discoveries increase the number of detached, double degenerate binaries in the elm survey to 54 ; 31 of these binaries will merge within a hubble time.
we report on the analysis of high - speed photometry of the dwarf - nova hs1804 + 67 through its outburst cycle with eclipse mapping techniques.   eclipse maps show evidences of the formation of a spiral structure in the disc at the early stages of the outburst and reveal how the disc expands during the rise until its fills most of the primary roche lobe at maximum light. during the decline phase,   the disc becomes progressively fainter as the cooling front moves inwards from the outer regions, until only a small bright region around the white dwarf is left at minimum light.   the variable part of the uneclipsed light is possibly due to emission in a wind emanating from the inner parts of the disc.   the emission from this region is sensitive to the mass accretion rate.    #   1#2#3#4#5#6#7    to#2   ''' ''    -15 mm
we study solitonic solutions of a deformed wess - zumino model in 2 dimensions, corresponding to a deformation of the usual @xmath0 superspace to the one with non - anticommuting odd supercoordinates.the deformation turns out to add a kinetic term for the auxiliary field besides the known @xmath1 term coming from the deformation of the cubic superpotential.   both these modifications are proportional to the effective deformation parameter @xmath2, where @xmath3 denotes the non - anticommutativity matrix.   we find a modified `` orbit '' equation which on the eom relates the auxiliary and the scalar components of the scalar superfield as a first order correction to the usual relation in terms of the small parameter @xmath4.   subsequently, we obtain the modified form of the first order bps equation for the scalar field and find its solution to first order in @xmath4.   issues such as modification of the bps mass formula and a non - linear realization of the @xmath5 supersymmetry are discussed.    0.5 cm * reza abbaspur *   +.25 in _ institute for studies in theoretical physics and mathematics, + p.o.   box 19395 - 5531, tehran, iran.   + _    0.5 cm
structure - preserving numerical schemes for a nonlinear parabolic fourth - order equation, modeling the electron transport in quantum semiconductors, with periodic boundary conditions are analyzed.   first, a two - step backward differentiation formula ( bdf ) semi - discretization in time is investigated.   the scheme preserves the nonnegativity of the solution, is entropy stable and dissipates a modified entropy functional.   the existence of a weak semi - discrete solution and, in a particular case, its temporal second - order convergence to the continuous solution is proved.   the proofs employ an algebraic relation which implies the g - stability of the two - step bdf.   second, an implicit euler and @xmath0-step bdf discrete variational derivative method are considered.   this scheme, which exploits the variational structure of the equation, dissipates the discrete fisher information ( or energy ).   numerical experiments show that the discrete ( relative ) entropies and fisher information decay even exponentially fast to zero.
there are only a few sources that are definitely known to be gamma - ray binaries.   two of these are listed as associations in the fermi lat bright source list.   we are developing novel techniques to extract high signal - to - noise light curves of all cataloged fermi sources and to search for periodic variability using appropriately weighted power spectra.   the detection of periodic variability would be strong evidence for the detection of a new gamma - ray binary.   the lat s sensitivity provides the opportunity to open up completely new discovery space for additional binary systems, potentially involving novel astrophysics.   we present here demonstrations of the sensitivity gains obtained through the use of these techniques.
we study dynamical effects in proton breakup from a weakly bound state in an exotic nucleus on a heavy target.   the coulomb interactions between the proton and the core and the proton and the target are treated to all orders, including also the full multipole expansion of the coulomb potential.   the dynamics of proton nuclear and coulomb breakup is compared to that of an _ equivalent _ neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism.   a number of experimentally measurable observables such as parallel momentum distributions, proton angular distributions and total breakup cross sections are calculated. with respect to nuclear breakup   it is found that a proton behaves exactly as a neutron of larger binding energy.   the extra `` effective energy '' is due to the combined core - target coulomb barrier. in coulomb breakup   we distinguish the effect of the core - target coulomb potential ( called recoil effect ), with respect to which the proton behaves again as a more bound neutron, from the direct proton - target coulomb potential.   the latter gives cross sections about an order of magnitude larger than the recoil term.   the two effects give rise to complicated interferences in the parallel momentum distributions.   they are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies.    *   pacs * 21.10.jx, 24.10.-i, 25.60.gc, 27.30.+t
we construct hadronic axion models in the framework of the anomaly - mediated supersymmetry breaking scenario. if the peccei - quinn symmetry breaking is related to the supersymmetry breaking, mass spectrum of the minimal anomaly - mediated scenario is modified, which may solve the negative slepton mass problem in the minimal anomaly - mediated model.   we find several classes of phenomenologically viable models of axion within the framework of the anomaly mediation and, in particular, we point out a new mechanism of stabilizing the axion potential. in this class of models,   the peccei - quinn scale is related to the messenger scale.   we also study phenomenological aspects of this class of models.   we will see that, in some case, the lightest particle among the superpartners of the standard - model particles is stau while the lightest superparticle becomes the axino, the superpartner of the axion.   with such a unique mass spectrum, conventional studies of the collider physics and cosmology for supersymmetric models should be altered.   tu-634 + hep - ph/0111155 + november, 2001 +.5 in    * anomaly - mediated supersymmetry breaking + with axion *   .45 in    nobutaka abe, takeo moroi and masahiro yamaguchi   .45 in    _ department of physics, tohoku university + sendai 980 - 8578, japan _   .4 in
based on the measurement of quantum correlation functions, the quantum statistical properties of spectral measurements are studied for broadband radiation fields.   the spectral filtering of light before its detection is compared with the direct detection followed by the spectral analysis of the recorded photocurrents. as an example, the squeezing spectra of the atomic resonance fluorescence are studied for both types of filtering procedures. the conditions for which the detection of the nonclassical signatures of the radiation is possible are analyzed. for the considered example, photocurrent filtering appears to be the superior option to detect nonclassicality, due to the vacuum - noise effects in the optical filtering.
the spread of new ideas, behaviors or technologies has been extensively studied using epidemic models. here   we consider a model of diffusion where the individuals behavior is the result of a strategic choice.   we study a simple coordination game with binary choice and give a condition for a new action to become widespread in a random network.   we also analyze the possible equilibria of this game and identify conditions for the coexistence of both strategies in large connected sets.   finally we look at how can firms use social networks to promote their goals with limited information.   our results differ strongly from the one derived with epidemic models and show that connectivity plays an ambiguous role : while it allows the diffusion to spread, when the network is highly connected, the diffusion is also limited by high - degree nodes which are very stable.   * keywords : * social networks, diffusion, random graphs, empirical distribution    * jel codes : * c73, o33, l14
we study the late time evolution of positively curved frw models with a scalar field which arises in the conformal frame of the @xmath0 theory. the resulted three - dimensional dynamical system has two equilibrium solutions corresponding to a de sitter space and an ever expanding closed universe.   we analyze the structure of the first equilibrium with the methods of the center manifold theory and, for the second equilibrium we apply the normal form theory to obtain a simplified system, which we analyze with special phase plane methods.   it is shown that an initially expanding closed frw spacetime avoids recollapse.
we report on constraints on the lifetime of decaying gravitino dark matter in models with bilinear _   r_-parity violation derived from observations of cosmic - ray antiprotons with the pamela experiment. performing a scan over a viable set of cosmic - ray propagation parameters we find lower limits ranging from @xmath0s to @xmath1s for gravitino masses from roughly 100gev to 10tev. comparing these limits to constraints derived from gamma - ray and neutrino observations   we conclude that the presented antiproton limits are currently the strongest and most robust limits on the gravitino lifetime in the considered mass range.   these constraints correspond to upper limits on the size of the bilinear _   r_-parity breaking parameter in the range of @xmath2 to @xmath3.   dark matter decay, gravitino dark matter, cosmic - ray antiprotons 95.35.+d, 96.50.s- + _ report numbers : _   ftuam-14 - 40, ift - uam / csic-14 - 002
electronic realizations of neurons are of great interest as building blocks for neuromorphic computation.   electronic neurons should send signals into the input and output lines when subject to an input signal exceeding a given threshold, in such a way that they may affect all other parts of a neural network. here, we propose a design for a neuron that is based on molecular - electronics components and thus promises a very high level of integration.   we employ the monte carlo technique to simulate typical time evolutions of this system and thereby show that it indeed functions as a neuron.
we study the phase diagram of the kondo - lattice model with nearest - neighbor hopping in the square lattice by means of the variational monte carlo technique.   specifically, we analyze a wide class of variational wave functions that allow magnetic and superconducting order parameters, so to assess the possibility that superconductivity might emerge close to the magnetic instability, as often observed in heavy fermion systems.   indeed, we do find evidence of @xmath0-wave superconductivity in the paramagnetic sector, i.e., when magnetic order is not allowed in the variational wave function.   however, when magnetism is allowed, it completely covers the superconducting region, which thus disappears from the phase diagram.
we study stochastic acceleration models for the fermi bubbles.   turbulence is excited just behind the shock front via kelvin   helmholtz, rayleigh   taylor, or richtmyer  meshkov instabilities, and plasma particles are continuously accelerated by the interaction with the turbulence.   the turbulence gradually decays as it goes away from the shock fronts. adopting a phenomenological model for the stochastic acceleration  , we explicitly solve the temporal evolution of the particle energy distribution in the turbulence.   our results show that the spatial distribution of high - energy particles is different from those for a steady solution.   we also show that the contribution of electrons that escaped from the acceleration regions significantly softens the photon spectrum.   the photon spectrum and surface brightness profile are reproduced by our models.   if the escape efficiency is very high, the radio flux from the escaped low - energy electrons can be comparable to that of the wmap haze.   we also demonstrate hadronic models with the stochastic acceleration, but they are unlikely in the viewpoint of the energy budget.
ch cygni began producing rapid, stochastic optical variations with the onset of symbiotic activity in 1963.   we use changes in this flickering between 1997 and 2000 to diagnose the state of the accretion disk during this time. in the 1998 high state,   the luminosity of the @xmath0-band flickering component was typically more than 20 times higher than in the 1997 and 2000 low states.   therefore, the physical process or region that produces the flickering was also primarily responsible for the large optical flux increase in the 1998 high state. assuming that the rapid, stochastic optical variations in ch cygni come from the accretion disk, as in cataclysmic variable stars, a change in the accretion rate through the disk led to the 1998 bright state.   all flickering disappeared in 1999, when the accreting wd was eclipsed by the red giant orbiting with a period of approximately 14 yr, according to the ephemeris of hinkle et al. and   the interpretation of eyres et al.   we did not find any evidence for periodic or quasi - periodic oscillations in the optical emission from ch cygni in either the high or low state, and we discuss the implications for magnetic propeller models of this system. as one alternative to propeller models, we propose that the activity in ch cygni is driven by accretion through a disk with a thermal - viscous instability, similar to the instabilities believed to exist in dwarf novae and suggested for fu ori pre - main - sequence stars and soft x - ray transients.
driven surface diffusion occurs, for example, in molecular beam epitaxy when particles are deposited under an oblique angle.   elastic phase transitions happen when normal modes in crystals become soft due to the vanishing of certain elastic constants.   we show that these seemingly entirely disparate systems fall under appropriate conditions into the same universality class.   we derive the field theoretic hamiltonian for this universality class, and we use renormalized field theory to calculate critical exponents and logarithmic corrections for several experimentally relevant quantities.
the standard technique for measurement of random uncertainties of star formation histories ( sfhs ) is the bootstrap monte carlo, in which the color - magnitude diagram ( cmd ) is repeatedly resampled.   the variation in sfhs measured from the resampled cmds is assumed to represent the random uncertainty in the sfh measured from the original data.   however, this technique systematically and significantly underestimates the uncertainties for times in which the measured star formation rate is low or zero, leading to overly ( and incorrectly ) high confidence in that measurement.   this study proposes an alternative technique, the markov chain monte carlo ( mcmc ), which samples the probability distribution of the parameters used in the original solution to directly estimate confidence intervals. while the most commonly used mcmc algorithms are incapable of adequately sampling a probability distribution that can involve thousands of highly correlated dimensions, the hybrid monte carlo algorithm is shown to be extremely effective and efficient for this particular task.   several implementation details, such as the handling of implicit priors created by parameterization of the sfh, are discussed in detail.
we introduce the notion of background independent quantum field theory.   the distinguishing feature of this theory is that the dynamics can be formulated without recourse to a background metric structure.   we show in a simple model how the metric properties of spacetime can be recovered from the dynamics.   background independence is not only conceptually desirable but allows for the resolution of a problem haunting ordinary quantum field theory : the cosmological constant problem.
we compare the properties of three - body systems obtained with two - body potentials with pauli forbidden states and with the corresponding phase equivalent two - body potentials. in the first case   the forbidden states are explicitly excluded in the calculation.   differences arise due to the off - shell properties of these on - shell equivalent potentials.   we use the adiabatic hyperspherical method to formulate a practical prescription to exclude pauli forbidden states in three - body calculations.   schematic as well as realistic potentials are used.   almost indistinguishable results are obtained. + pacs number(s ) : 21.60.gx, 21.45.+v
we present self - consistent cosmological magnetohydrodynamic ( mhd ) simulations that simultaneously follow the formation of a galaxy cluster and the magnetic field ejection by an active galactic nucleus ( agn ).   we find that the magnetic fields ejected by the agns, though initially distributed in relatively small volumes, can be transported throughout the cluster and be further amplified by the intra - cluster medium ( icm ) turbulence during the cluster formation process.   the icm turbulence is shown to be generated and sustained by the frequent mergers of smaller halos.   furthermore, a cluster - wide dynamo process is shown to exist in the icm and amplify the magnetic field energy and flux.   the total magnetic energy in the cluster can reach @xmath0 @xmath1 ergs while micro gauss ( @xmath2 g ) fields can distribute over @xmath0 mpc scales throughout the whole cluster.   this finding shows that magnetic fields from agns, being further amplified by the icm turbulence through small - scale dynamo processes, can be the origin of cluster - wide magnetic fields.
earlier attempts to extract parameters of kinetic freeze - out in pb+pb collisions at 158@xmath0gev are critically reviewed.   many of these analyses have used approximations which have significant impact on the extracted parameters.   simple estimates are obtained which attempt to avoid the most critical approximations.   it is pointed out that constraints based on pion interferometry are less reliable than those from momentum spectra.   a universal set of freeze - out parameters from transverse mass spectra would require @xmath1 and @xmath2.
it has recently been noticed that quantum gates can be performed faster and can utilize interaction between qubits more effectively if performed via continuous time quantum walks through states outside of the computational basis.   we formulate general requirements for such walks and illustrate them with examples of single-, two- and three - qubit gates, including hadamard, control - not, and toffoli gates.   continuous - time quantum walks on graphs involved in these gates are investigated.
we have investigated the mass accretion rate implied by published surface abundances of si and c in the white dwarf component of the 3.62  hr period pre - cataclysmic binary and planet host candidate qs  vir ( da+m2 - 4 ).   diffusion timescales for gravitational settling imply @xmath0  yr@xmath1 for the 1999 epoch of the observations, which is three orders of magnitude lower than measured from a 2006 _ xmm - newton _ observation.   this is the first time that large accretion rate variations have been seen in a detached pre - cv.   a third body in a 14  yr eccentric orbit suggested in a recent eclipse timing study is too distant to perturb the central binary sufficiently to influence accretion.   a hypothetical coronal mass ejection just prior to the _ xmm - newton _ observation might explain the higher accretion rate, but the implied size and frequency of such events appear too great.   we suggest accretion is most likely modulated by a magnetic cycle on the secondary acting as a wind `` accretion switch '', a mechanism that can be tested by x - ray and ultraviolet monitoring.   if so, qs  vir and similar pre - cvs could provide powerful insights into hitherto inscrutable cataclysmic variable and m dwarf magnetospheres, and mass and angular momentum loss rates.   novae, cataclysmic variables  accretion, accretion discs  binaries : eclipsing  stars : coronae  stars : winds, outflows  x - rays : stars
_ security and distributed infrastructure are two of the most common requirements for big data software.   but the security features of the big data platforms are still premature.   it is critical to identify, modify, test and execute some of the existing security mechanisms before using them in the big data world. in this paper, we propose a novel intrusion detection technique that understands and works according to the needs of big data systems.   our proposed technique identifies program level anomalies using two methods - a * profiling method * that models application behavior by creating process signatures from control - flow graphs ; and a * matching method * that checks for coherence among the replica nodes of a big data system by matching the process signatures.   the profiling method creates a process signature by reducing the control - flow graph of a process to a set of minimum spanning trees and then creates a hash of that set. the matching method first checks for similarity in process behavior by matching the received process signature with the local signature and then shares the result with all replica datanodes for consensus.   experimental results show only 0.8% overhead due to the proposed technique when tested on the hadoop map - reduce examples in real - time. _    big data ; intrusion detection ; control - flow graph ;
in this paper, we present measurements of the ortho - positronium emission energy in vacuum from mesoporous films using the time of flight technique.   we show evidence of quantum mechanical confinement in the mesopores that defines the minimal energy of the emitted ps.   two samples with different effective pore sizes, measured with positron annihilation lifetime spectroscopy, are compared for the data collected in the temperature range 50 - 400 k. the sample with smaller pore size exhibits a higher minimal energy ( @xmath05 mev ), compared to the sample with bigger pores ( @xmath15 mev ), due to the stronger confinement.   the dependence of the emission energy with the temperature of the target is modeled as ortho - positronium being confined in rectangular boxes in thermodynamic equilibrium with the sample.   we also measured that the yield of positronium emitted in vacuum is not affected by the temperature of the target.
we investigate the quantum behavior of a mesoscopic two - boson system produced by number - squeezing ultracold gases of alkali metal atoms.   the quantum poincare maps of the wavefunctions are affected by chaos in those regions of the phase space where the classical dynamics produces features that are comparable to @xmath0.   we also investigate the possibility for quantum control in the dynamics of excitations in these systems.   controlled excitations are mediated by pulsed signals that cause stimulated raman adiabatic passage ( stirap ) from the ground state to a state of higher energy.   the dynamics of this transition is affected by chaos caused by the pulses in certain regions of the phase space. a transition to chaos   can thus provide a method of controlling stirap.
we discuss the relevance of studying ecology within the framework of complexity science from a statistical mechanics approach.   ecology is concerned with understanding how systems level properties emerge out of the multitude of interactions amongst large numbers of components, leading to ecosystems that possess the prototypical characteristics of complex systems.   we argue that statistical mechanics is at present the best methodology available to obtain a quantitative description of complex systems, and that ecology is in urgent need of `` integrative '' approaches that are quantitative and non - stationary.   we describe examples where combining statistical mechanics and ecology has led to improved ecological modelling and, at the same time, broadened the scope of statistical mechanics.   * keywords : * complexity, statistical mechanics, emergence, evolution, ecology.
networked communications inherently depend on the ability of the sender of a message to indicate through some token how the message should be delivered to a particular recipient.   the tokens that refer messages to recipients are variously known as _ routes _, _ addresses _, _ handles _, and _ names _, ordered by their relative nearness to network topology vs.  human meaning.   all four sorts of token refer in some way to a recipient, but they are controlled by different authorities and their meanings depend on different contextual parameters.    today s global internet employs dynamically determined routes, ip addresses, and domain names.   domain names combine the functions of handles and names. the high value of domain names as names leads to substantial social and legal dispute about their assignment, degrading their value as handles.   the time has come to provide a distinct open network handle system ( onhs ), using handles that are not meaningful in natural language and are therefore not subject to the disputes surrounding the use of names.   a handle service may be deployed easily as a handle domain within the current domain name system. in order to minimize the administrative load, and maximize their own autonomy  , netizens may use public - key cryptography to assign their own handles.
after almost 2.5 years of actively accreting, the neutron star x - ray transient and eclipsing binary mxb 165929 returned to quiescence in 2001 september.   we report on a _ chandra _ observation of this source taken a little over a month after this transition.   the source was detected at an unabsorbed 0.510 kev flux of only @xmath0 erg @xmath1 s@xmath2, which implies a 0.510 kev x - ray luminosity of approximately @xmath3 erg s@xmath2, with @xmath4 the distance to the source in kpc.   its spectrum had a thermal shape and could be well fitted by either a blackbody with a temperature @xmath5 of @xmath6 kev or a neutron star atmosphere model with a @xmath5 of @xmath7 kev.   the luminosity and spectral shape of mxb 165929 are very similar to those observed of the other neutron star x - ray transients when they are in their quiescent state.   the source was variable during our observation, exhibiting a complete eclipse of the inner part of the system by the companion star.   dipping behavior was observed before the eclipse, likely due to obscuration by an extended feature in the outer part of a residual accretion disk.   we discuss our observation in the context of the cooling neutron star model proposed to explain the quiescent properties of neutron star x - ray transients.
we study the ground state properties of a superconductor - ferromagnet - insulator trilayer on the basis of a hubbard model featuring exchange splitting in the ferromagnet and electron - electron attraction in the superconductor.   we solve the spin - polarized hartree - fock - gorkov equations together with the maxwell s equation ( ampere s law ) fully self - consistently. for certain values of the exchange splitting   we find that a spontaneous spin polarized current is generated in the ground state and is intimately related to andreev bound states at the fermi level.   moreover, the polarization of the current strongly depends on the band filling.
we investigated the influence of efficacy of synaptic interaction on firing synchronization in excitatory neuronal networks.   we found spike death phenomena, namely, the state of neurons transits from limit cycle to fixed point or transient state.   the phenomena occur under the perturbation of excitatory synaptic interaction that has a high efficacy.   we showed that the decrease of synaptic current results in spike death through depressing the feedback of sodium ionic current. in the networks with spike death property   the degree of synchronization is lower and unsensitive to the heterogeneity of neurons.   the mechanism of the influence is that the transition of neuron state disrupts the adjustment of the rhythm of neuron oscillation and prevents further increase of firing synchronization.
abell 1689 is a galaxy cluster at @xmath0 where previous measurements of its mass using various techniques gave discrepant results.   we present a new detailed measurement of the mass with the data based on x - ray observations with the european photon imaging camera aboard the xmm - newton observatory, determined by using an unparameterized deprojection technique. fitting the total mass profile to a navarro - frenk - white model yields halo concentration @xmath1 and @xmath2, corresponding to a mass which is less than half of what is found from gravitational lensing.   adding to the evidence of substructure from optical observations, x - ray analysis shows a highly asymmetric temperature profile and a non - uniform redshift distribution implying large scale relative motion of the gas.   a lower than expected gas mass fraction @xmath3 ( for a flat @xmath4cdm cosmology ) suggests a complex spatial and/or dynamical structure.   we also find no signs of any additional absorbing component previously reported on the basis of the chandra data, confirming the xmm low energy response using data from rosat.
we use new mid - infrared ( mid - ir ) photometry from the _ spitzer space telescope _ to study the relations between low - frequency radio luminosity density @xmath0, mid - ir ( @xmath1 m rest - frame ) luminosity @xmath2, and optical - emission - line (  ) luminosity @xmath3}$ ], for a complete sample of @xmath4 radio galaxies from the 3crr, 6ce, 6c *, 7crs and toot00 surveys. the narrow redshift span of our sample ( @xmath5 ) means that it is unbiased to evolutionary effects. we find evidence that these three quantities are positively correlated. the scaling between @xmath2 and @xmath6}$ ] is similar to that seen in other agn samples, consistent with both @xmath2 and @xmath3}$ ] tracing accretion rate. we show that the positive correlation between @xmath7 and @xmath0 implies that there is a genuine lack of objects with low values of @xmath2 at high values of @xmath0. given that @xmath8 traces accretion rate, while @xmath0 traces jet power, this can be understood in terms of a minimum accretion rate being necessary to produce a given jet power.   this implies that there is a maximum efficiency with which accreted energy can be chanelled into jet power and that this efficiency is of order unity.       galaxies : active - galaxies : jets - infrared : galaxies - radio continuum : galaxies - quasars : general - galaxies : nuclei
after a short history of the @xmath0-term it is explained why the ( effective ) cosmological constant is expected to obtain contributions from short - distance physics, corresponding to an energy at least as large as the fermi scale.   the actual tiny value of the cosmological constant by particle physics standards represents, therefore, one of the deepest mysteries of present - day fundamental physics.   recent proposals of an approach to the cosmological constant problem which make use of ( large ) extra dimensions are briefly discussed.   cosmological models with a dynamical @xmath0, which attempt to avoid the disturbing cosmic coincidence problem, are also reviewed.
the problem of optimally discriminating between two completely unknown qubit states is generalized by allowing an error margin.   it is visualized as a device  the programmable discriminator  with one data and two program ports, each fed with a number of identically prepared qubits  the data and the programs.   the device aims at correctly identifying the data state with one of the two program states.   this scheme has the unambiguous and the minimum error schemes as extremal cases, when the error margin is set to zero or it is sufficiently large, respectively.   analytical results are given in the two situations where the margin is imposed on the average error probability  weak condition  or it is imposed separately on the two probabilities of assigning the state of the data to the wrong program  strong condition.   it is a general feature of our scheme that the success probability rises sharply as soon as a small error margin is allowed, thus providing a significant gain over the unambiguous scheme while still having high confidence results.
the advent of social media expands our ability to transmit information and connect with others instantly, which enables us to behave as `` social sensors. '' here, we studied concurrent bursty behavior of twitter users during major sporting events to determine their function as social sensors. we show that the degree of concurrent bursts in tweets ( posts ) and retweets ( re - posts ) works as a strong indicator of winning or losing a game.   more specifically, our simple tweet analysis of japanese professional baseball games in 2013 revealed that social sensors can immediately react to positive and negative events through bursts of tweets, but that positive events are more likely to induce a subsequent burst of retweets.   we confirm that these findings also hold true for tweets related to major league baseball games in 2015.   furthermore, we demonstrate active interactions among social sensors by constructing retweet networks during a baseball game.   the resulting networks commonly exhibited user clusters depending on the baseball team, with a scale - free connectedness that is indicative of a substantial difference in user popularity as an information source. while previous studies have mainly focused on bursts of tweets as a simple indicator of a real - world event, the temporal correlation between tweets and retweets implies unique aspects of social sensors, offering new insights into human behavior in a highly connected world.
the finite size effects of the nanoparticles to the atomic pair distribution functions ( pdf ) are discussed by calculating the radial distribution functions ( rdf ) on nanoparticles with various shapes, such as sheet, belt, rod, tube and sphere, assuming continua.   their characteristics are shown depending on the shapes and the sizes of the nanoparticles.   alternately, these pdfs can be used to measure the shapes and the sizes of ordered lattice part inside of any materials such as nanoparticles and bulks.   iikubo    shamoto    the finite size effects of nanoparticles to the atomic pair distribution function ( pdf ) are calculated, which are essential to the structural analysis on nanoparticles.
a beam line for electrons with energies in the range of 1 to 45 gev, low contamination of hadrons and muons and high intensity up to 10@xmath0 per accelerator spill at 27 gev was setup at u70 accelerator in protvino, russia. a beam tagging system based on drift chambers with 160  @xmath1 m resolution was able to measure relative electron beam momentum precisely.   the resolution @xmath2/p was 0.13% at 45  gev where multiple scattering is negligible.   this test beam setup provided a possibility to study properties of lead tungstate crystals ( pbwo@xmath3 ) for the btev experiment at fermilab.   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,
we introduce complex cones and associated projective gauges, generalizing a real birkhoff cone and its hilbert metric to complex vector spaces.   we deduce a variety of _ spectral gap _ theorems in complex banach spaces.   we prove a _ dominated _ complex cone - contraction theorem and use it to extend the classical perron - frobenius theorem to complex matrices, jentzsch s theorem to complex integral operators, a kren - rutman theorem to compact and quasi - compact complex operators and a ruelle - perron - frobenius theorem to complex transfer operators in dynamical systems. in the simplest case of a complex @xmath0 by @xmath0 matrix @xmath1   we have the following statement  : suppose that @xmath2 is such that @xmath3 for all indices.   then @xmath4 has a ` spectral gap '.
star formation in the local spiral arm in the direction of the galactic longitudes 132158@xmath0 is reviewed.   recent star - forming activity in this milky way direction is evidenced by the presence here of the cam ob1 association and dense dust and molecular clouds containing h@xmath1 emission stars, young irregular variables and infrared stellar objects.   the clouds of the local arm concentrate in two layers at 150300 pc and @xmath2900 pc from the sun.   the perseus arm objects in this direction are at a distance of about 2 kpc.
kaon photo- and electroproduction off a proton near the production threshold are investigated by utilizing an isobar model.   the background amplitude of the model is constructed from feynman diagrams, whereas the resonance term is calculated by using the multipole formalism.   it is found that both pseudoscalar and pseudovector models can nicely describe the available photoproduction data up to @xmath0 mev above the threshold.   the @xmath1 resonance @xmath2 is found to play an important role in improving the model. in the case of double polarization   observables @xmath3 and @xmath4 our result corroborates the finding of sandorfi _ et al. _ due to the large contributions of the @xmath5 and @xmath6 vector mesons, extending the model to the case of electroproduction is almost impossible unless either special form factors that strongly suppress their contributions are introduced or all hadronic coupling constants are refitted to both photo- and electroproduction databases, simultaneously.   it is also concluded that investigation of the kaon electromagnetic form factor is not recommended near the threshold region.
the role of long range badly screened coulomb interactions in a one - dimensional chain of josephson junctions is studied.   correlation functions for the phase correlator are obtained as a function of the josephson coupling energy, the short range part of coulomb repulsion and its long range component.   though quasi - long range order is no longer possible and the usual kosterlitz - thouless transition no longer exists, there are remnants of it. as an application, we calculate the @xmath0 curves for andreev reflexion when a normal metal is placed in contact with the chain.   formally, there is always an offset voltage @xmath1 below which no current can flow, however, in some regimes @xmath1 can be negligible.   contrary to what happens without long - range interactions, the andreev current, as a function of applied voltage, increases faster than any power law.   signatures of long range interactions and phase slips appear in the @xmath0 curves.   possible application for quasi one - dimensional thin superconducting wires is outlined.
nuclear level densities for @xmath0fe have been extracted from the primary @xmath1-ray spectra using ( @xmath2he,@xmath2he@xmath3 ) and ( @xmath2he,@xmath4 ) reactions.   nuclear thermodynamic properties for @xmath5fe and @xmath6fe are investigated using the experimental level densities.   these properties include entropy, helmholtz free energy, caloric curves, chemical potential, and heat capacity.   in particular, the breaking of cooper pairs and single - quasiparticle entropy are discussed and shown to be important concepts for describing nuclear level density.   microscopic model calculations are performed for level densities of @xmath0fe.   the experimental and calculated level densities are compared.   the average number of broken cooper pairs and the parity distribution are extracted as a function of excitation energy for @xmath0fe from the model calculations.
in many non - integrable open systems in physics and mathematics resonances have been found to be surprisingly ordered along curved lines in the complex plane. in this article we provide a unifying approach to these resonance chains by generalizing dynamical zeta functions. by means of a detailed numerical study   we show that these generalized zeta functions explain the mechanism that creates the chains of quantum resonance and classical ruelle resonances for 3-disk systems as well as geometric resonances on schottky surfaces.   we also present a direct system - intrinsic definition of the continuous lines on which the resonances are strung together as a projection of an analytic variety.   additionally, this approach shows that the existence of resonance chains is directly related to a clustering of the classical length spectrum on multiples of a base length.   finally, this link is used to construct new examples where several different structures of resonance chains coexist.
recently, a quasi - orthogonal space - time block code ( qstbc ) capable of achieving a significant fraction of the outage mutual information of a multiple - input - multiple output ( mimo ) wireless communication system for the case of four transmit and one receive antennas was proposed.   we generalize these results to @xmath0 transmit and an arbitrary number of receive antennas @xmath1.   furthermore, we completely characterize the structure of the equivalent channel for the general case and show that for all @xmath0 and @xmath1 the eigenvectors of the equivalent channel are fixed and independent from the channel realization.   furthermore, the eigenvalues of the equivalent channel are independent identically distributed random variables each following a noncentral chi - square distribution with @xmath2 degrees of freedom. based on these important insights into the structure of the qstbc, we derive an analytical lower bound for the fraction of outage probability achieved with qstbc and show that this bound is tight for low signal - to - noise - ratios ( snr ) values and also for increasing number of receive antennas.   we also present an upper bound, which is tight for high snr values and derive analytical expressions for the case of four transmit antennas.   finally, by utilizing the special structure of the qstbc we propose a new transmit strategy, which decouples the signals transmitted from different antennas in order to detect the symbols separately with a linear ml - detector rather than joint detection, an up to now only known advantage of orthogonal space - time block codes ( ostbc ).
concrete computing machines, either sequential or concurrent, rely on an intimate relation between computation and time.   we recall the general characteristic properties of physical time and of present realizations of computing systems.   we emphasize the role of computing interferences, i.e. the necessity to avoid them in order to give a causal implementation to logical operations.   we compare synchronous and asynchronous systems, and make a brief survey of some methods used to deal with computing interferences. using a graphic representation, we show that synchronous and asynchronous circuits reflect the same opposition as the newtonian and relativistic causal structures for physical space - time.
we provide optimal measurement schemes for estimating relative parameters of the quantum state of a pair of spin systems.   we prove that the optimal measurements are joint measurements on the pair of systems, meaning that they can not be achieved by local operations and classical communication.   we also demonstrate that in the limit where one of the spins becomes macroscopic, our results reproduce those that are obtained by treating that spin as a classical reference direction.
the curved actin `` comet - tail '' of the bacterium _   listeria monocytogenes _ is a visually striking signature of actin polymerization - based motility.   similar actin tails are associated with _   shigella flexneri _,   spotted - fever _ rickettsiae _, the _ vaccinia _ virus, and vesicles and microspheres in related _ in vitro _ systems.   we show that the torque required to produce the curvature in the tail can arise from randomly placed actin filaments pushing the bacterium or particle.   we find that the curvature magnitude determines the number of actively pushing filaments, independent of viscosity and of the molecular details of force generation.   the variation of the curvature with time can be used to infer the dynamics of actin filaments at the bacterial surface.
we report the first wide - field mapping of the kinematics and stellar populations in the e3 galaxy ngc4365.   the velocity maps extend previous long - slit work.   they show two independent kinematic subsystems : the central @xmath0  pc rotates about the projected minor axis, and the main body of the galaxy, @xmath1  kpc, rotates almost at right angles to this.   the line - strength maps show that the metallicity of the stellar population decreases from a central value greater than solar, to one - half solar at a radius of 2  kpc.   the decoupled core and main body of the galaxy have the same luminosity - weighted age, of @xmath214  gyr, and the same elevated magnesium - to - iron ratio.   the two kinematically distinct components have thus shared a common star formation history.   we infer that the galaxy underwent a sequence of mergers associated with dissipative star formation that ended @xmath312  gyr ago.   the misalignment between the photometric and kinematic axes of the main body is unambiguous evidence of triaxiality.   the similarity of the stellar populations in the two components suggests that the observed kinematic structure has not changed substantially in 12  gyr.   # 1to 0pt#1
using the nonequilibrium theory of superconductivity with the tunnel hamiltonian, we consider a mesoscopic nisinisin heterostructure, i.e., a structure consisting of five intermittent normal - metal ( n ) and superconducting ( s ) regions separated by insulating tunnel barriers ( i ). applying the bias voltage between the outer normal electrodes one can drive the central n island very far from equilibrium. depending on the resistance ratio of outer and inner tunnel junctions  , one can realize either effective electron cooling in the central n island or create highly nonequilibrium energy distributions of electrons in both s and n islands.   these distributions exhibit multiple peaks at a distance of integer multiples of the superconducting chemical potential. in the latter case the superconducting gap in the s islands   is strongly suppressed as compared to its equilibrium value.
stars in the solar neighbourhood do not have a smooth distribution of velocities.   instead, the distribution of velocity components in the galactic plane manifests a great deal of kinematic substructure. here   i present an analysis in action - angle variables of the geneva - copenhagen survey of @xmath0 nearby f & g dwarfs with distances and full space motions.   i show that stars in the so - called `` hyades stream '' have both angle and action variables characteristic of their having been scattered at an inner lindblad resonance of a rotating disturbance potential.   this discovery seems to favour spiral patterns as recurrent, short - lived instabilities.       galaxies : evolution  galaxies : kinematics and dynamics  galaxies : spiral
the linear hydrodynamic stability of a model for confined quasi - two - dimensional granular gases is analyzed.   the system exhibits homogeneous hydrodynamics, i.e. there are macroscopic evolution equations for homogeneous states.   the stability analysis is carried out around all these states and not only the homogeneous steady state reached eventually by the system.   it is shown that in some cases the linear analysis is not enough to reach a definite conclusion on the stability, and molecular dynamics simulation results are presented to elucidate these cases.   the analysis shows the relevance of nonlinear hydrodynamic contributions to describe the behavior of spontaneous fluctuations occurring in the system, that lead even to the transitory formation of clusters of particles.   the conclusion is that the system is always stable.   the relevance of the results for describing the instabilities of confined granular gases observed experimentally is discussed.
the particle - hole density matrix renormalization group ( p - h dmrg ) method is discussed as a possible new approach to large - scale nuclear shell - model calculations. following a general description of the method  , we apply it to a class of problems involving many identical nucleons constrained to move in a single large j  shell and to interact via a pairing plus quadrupole interaction. a single - particle term that splits the shell into degenerate doublets   is included so as to accommodate the physics of a fermi surface in the problem.   we apply the p - h dmrg method to this test problem for two @xmath0 values, one for which the shell model can be solved exactly and one for which the size of the hamiltonian is much too large for exact treatment. in the former case,   the method is able to reproduce the exact results for the ground state energy, the energies of low  lying excited states, and other observables with extreme precision. in the latter case, the results exhibit rapid exponential convergence, suggesting the great promise of this new methodology even for more realistic nuclear systems.   we also compare the results of the test calculation with those from hartree  fock   bogolyubov approximation and address several other questions about the p - h dmrg method of relevance to its usefulness when treating more realistic nuclear systems.   * pacs numbers : * 21.60.cs, 05.10.cc +    2
@xmath0band imaging of a sample of 21 radiogalaxies with @xmath1 reveals the existence of a statistical association of foreground galaxies with the positions of the radiosources.   the excess is detected within a 1 radius at a high significance level ( @xmath2 ).   @xmath3-band light is a good tracer of stellar mass, so this result indicates the existence of an association between foreground mass perturbations and background radiosources, as expected from the magnification bias effect, and confirms previous results obtained for other high@xmath4 radio - loud agn.
we investigate both experimentally and theoretically disorder induced damping of bloch oscillations of bose - einstein condensates in optical lattices.   the spatially inhomogeneous force responsible for the damping is realised by a combination of a disordered optical and a magnetic gradient potential.   we show that the inhomogeneity of this force results in a broadening of the quasimomentum spectrum, which in turn causes damping of the centre - of - mass oscillation.   we quantitatively compare the obtained damping rates to the simulations using the gross - pitaevskii equation.   our results are relevant for high precision experiments on very small forces, which require the observation of a large number of oscillation cycles.
* abstract*we suggest a new mechanism to account for the loss of angular momentum in binaries with non - conservative mass exchange.   it is shown that in some cases the loss of matter can result in increase of the orbital angular momentum of a binary.   if included into consideration in evolutionary calculations, this mechanism appreciably extends the range of mass ratios of components for which mass exchange in binaries is stable.   it becomes possible to explain the existence of some observed cataclysmic binaries with high donor / accretor mass ratio, which was prohibited in conservative evolution models.   # 1#2#1#2 # 1#2    = 0
using a non - thermal local search, called extremal optimization ( eo ), in conjunction with a recently developed scheme for classifying the valley structure of complex systems, we analyze a short - range spin glass. in comparison with earlier studies using a thermal algorithm with detailed balance,   we determine which features of the landscape are algorithm dependent and which are inherently geometrical.   apparently a characteristic for any local search in complex energy landscapes, the time series of successive energy records found by eo also is characterized approximately by a log - poisson statistics.   differences in the results provide additional insights into the performance of eo.   in contrast with a thermal search, the extremal search visits dramatically higher energies while returning to more widely separated low - energy configurations.   two important properties of the energy landscape are independent of either algorithm : first, to find lower energy records, progressively higher energy barriers need to be overcome.   second, the hamming distance between two consecutive low - energy records is linearly related to the height of the intervening barrier.   pacs number(s ) : 05.40.-a, 75.10.nr, 02.60.pn.
based on a mesoscopic theory we investigate the non - equilibrium dynamics of a sheared nematic liquid, with the control parameter being the shear stress @xmath0 ( rather than the usual shear rate, @xmath1 ). to this end   we supplement the equations of motion for the orientational order parameters by an equation for @xmath1, which then becomes time - dependent. shearing the system from an isotropic state, the stress - controlled flow properties turn out to be essentially identical to those at fixed @xmath1.   pronounced differences occur when the equilibrium state is nematic. here,   shearing at controlled @xmath1 yields several non - equilibrium transitions between different dynamic states, including chaotic regimes.   the corresponding stress - controlled system has only one transition from a regular periodic into a stationary ( shear - aligned ) state.   the position of this transition in the @xmath0-@xmath1 plane turns out to be tunable by the delay time entering our control scheme for @xmath0.   moreover, a sudden change of the control method can _ stabilize _ the chaotic states appearing at fixed @xmath1.
of all pulsars known vela has been one of the most productive in terms in understanding pulsars and their characteristics.   we present the latest results derived from australian telescopes.   these include a more accurate pulsar distance, a more precise pulsar local space velocity, a new model of the spin up and the association of a radio nebula with the x - ray pulsar wind nebula.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we simulate scanning probe imaging of the local density of states related to scattering fermi level wave functions inside a resonant cavity.   we calculate potential landscape within the cavity taking into account the coulomb charge of the probe and its screening by deformation of the two - dimensional electron gas using the local density approximation.   approximation of the tip potential by a lorentz function is discussed.   the electron transfer problem is solved with a finite difference approach.   we look for stable work points for the extraction of the local density of states from conductance maps.   we find that conductance maps are highly correlated with the local density of states when the fermi energy level enters into fano resonance with states localized within the cavity.   generally outside resonances the correlation between the local density of states and conductance maps is low.
we explore vortex formation for abelian projected su(2 ) in the polyakov gauge and compare the results with those calculated in the maximal abelian gauge. in both gauges,   a non - zero vacuum expectation value of a monopole field operator signals confinement.   we find vortices in the polyakov projection, confirming the connection between the dual superconductor order parameter and the existence of vortices.   however we find that the polyakov abelian projection is problematic, leaving the maximal abelian projection as the best candidate to define an effective theory of confinement in this scenario.
in this paper, i mention a few processes which may play a role in the evolution of the central regions of galaxies. in this context  , i briefly discuss some issues regarding the formation of bulges in spirals, the role of supermassive black holes, and the importance of nuclear density waves.
the source - coding problem with side information at the decoder is studied subject to a constraint that the encoder  to whom the side information is unavailable  be able to compute the decoder s reconstruction sequence to within some distortion. for discrete memoryless sources and finite single - letter distortion measures,   an expression is given for the minimal description rate as a function of the joint law of the source and side information and of the allowed distortions at the encoder and at the decoder.   the minimal description rate is also computed for a memoryless gaussian source with squared - error distortion measures.   a solution is also provided to a more general problem where there are more than two distortion constraints and each distortion function may be a function of three arguments : the source symbol, the encoder s reconstruction symbol, and the decoder s reconstruction symbol.
we extend the polyakov - nambu - jona - lasinio ( pnjl ) model for two degenerate flavours by including the effect of the su(3 ) measure with a vandermonde ( vdm ) term.   this ensures that the polyakov loop always remains in the domain .   the pressure, energy density, specific heat, speed of sound and conformal measure show small or negligible effects from this term.   however various quark number and isospin susceptibilities are all found to approach their respective ideal gas limits around 2 @xmath0.   we compare our methods with other similar approaches in pnjl model and also present a quantitative comparison with lattice qcd data.
we calculate all multipoint correlation functions of all local bond modifications in the two - dimensional abelian sandpile model, both at the critical point, and in the model with dissipation.   the set of local bond modifications includes, as the most physically interesting case, all weakly allowed cluster variables.   the correlation functions show that all local bond modifications have scaling dimension two, and can be written as linear combinations of operators in the central charge @xmath0 logarithmic conformal field theory, in agreement with a form conjectured earlier by mahieu and ruelle in phys.   rev.   e * 64 *, 066130 ( 2001 ).   we find closed form expressions for the coefficients of the operators, and describe methods that allow their rapid calculation.   we determine the fields associated with adding or removing bonds, both in the bulk, and along open and closed boundaries ; some bond defects have scaling dimension two, while others have scaling dimension four.   we also determine the corrections to bulk probabilities for local bond modifications near open and closed boundaries.
the network of barabasi and albert, a preferential growth model where a new node is linked to the old ones with a probability proportional to their connectivity, is applied to brazilian election results.   the application of the sznajd rule, that only agreeing pairs of people can convince their neighbours, gives a vote distribution in good agreement with reality.    * election results and the sznajd model on barabasi network *    a. t. bernardes@xmath0, d. stauffer@xmath1 and j. kertsz@xmath2    @xmath3 departamento de fsica, universidade federal de ouro preto, campus do morro do cruzeiro, 35400 - 000, ouro preto - mg, brazil    @xmath4 institute for theoretical physics, cologne university, d-50923 kln, euroland    @xmath5department of theoretical physics, budapest university of technology and economics, budafoki t 8, h-1111, budapest, hungary    e - mails : atb@iceb.ufop.br, stauffer@thp.uni-koeln.de, kertesz@phy.bme.hu    keywords : sociophysics, dynamics, networks
gravity can be thought as an emergent phenomenon and it has a nice `` thermodynamic '' structure. in this context, it is then possible to study the thermodynamics without knowing the details of the underlying microscopic degrees of freedom. here,   based on the ordinary thermodynamics, we investigate the phase transition of the static, spherically symmetric charged black hole solution with arbitrary scalar curvature @xmath0 in hoava - lifshitz gravity at the lifshitz point @xmath1. the analysis is done using the _ canonical ensemble _ frame work ; i.e. the charge is kept fixed.   we find ( a ) for both @xmath2 and @xmath3, there is no phase transition, ( b ) while @xmath4 case exhibits the second order phase transition within the _ physical region _ of the black hole  . the critical point of second order phase transition is obtained by the divergence of the heat capacity at constant charge. near the critical point, we find the various critical exponents.   it is also observed that they sati sfy the usual thermodynamic scaling laws.
gamma - ray bursts ( grbs ) are believed to be powered by the electromagnetic extraction of spin energy from a black hole endowed with a magnetic field supported by electric currents in a surrounding disk ( blandford & znajek  1977 ).   a generic feature of this mechanism is that, under certain fairly general assumptions, the energy loss rate decays exponentially. in this work  , we are looking precisely for such exponential decay in the light curves of long duration grbs observed with the xrt instrument on the swift satellite.   we found out that almost 30% of xrt light curves show such behavior before they reach the afterglow plateau. according to blandford & znajek, the duration of the burst depends on the magnetic flux accumulated on the event horizon.   this allows us to estimate the surface magnetic field of a possible progenitor.   our estimations are consistent with magnetic fields observed in wolf - rayet stars.       gamma - ray bursts, black hole physics, magnetic fields, blandford - znajek
20 months of observations of the radio emission at 15 ghz from cygnus  x-1, starting in 1996 october, show variations at the binary period of 5.6 days, but with a phase offset from those at x - ray wavelengths.   there are also longer - term variations on a time - scale of 150 days which are only loosely related to the soft x - ray flux.   the source was in the hard / low x - ray state throughout this period.   the mean 15-ghz flux density is 13 mjy, the radio spectrum is flat, and the semi - amplitude of the orbital modulation about 2 mjy.   we discuss the possible origins of the modulation and the relationship to the soft x - ray emission.   radio continuum : stars  x - rays : stars  stars : individual : cygnus x-1
we study the dynamics of the photon entanglement, @xmath0, for the two - mode jaynes - cummings model in the few - photon case. the atomic transitions associated with the photons with different polarizations   are assumed to be independent and, hence, the evolution of the  @xmath1"- and   @xmath2"-polarized photons is formally separable.   however, due to the photons indistinguishability such interaction still leads to entanglement of initially disentangled states owing to the non - linear dependence of the characteristic frequencies on the photon population numbers.   the time dependence of entanglement is the result of superimposing oscillations with incommensurate frequencies.   therefore, @xmath0 is a quasi - periodic function of time with the complex profile strongly depending on the number of photons.
we re - examine the question of condensed neutrino objects ( degenerate neutrino matter ) based on new calculations.   the potential show - stopper issue of free - streaming light neutrinos inhibiting galaxy formation is addressed.   we compute the period associated with simple harmonic motion ( shm ) of galaxies embedded within condensed neutrino objects. for observational consequences, we examine the rotational velocities of embedded galaxies using hickson 88a ( n6978 ) as the prototype. finally, we point out that degenerate neutrino objects repel each other in overlap and we compute directly the repulsive force between two interesting and relevant configurations.   an outstanding issue is whether the accompanying tidal forces generated by condensed neutrino matter on embedded galaxies give rise to galactic bulges and halos.   shm of galaxies embedded within condensed neutrino matter    p.d.   morley + system of systems analytics, inc.   + 11250 waples mill road + suite 300 + fairfax, va 22030 - 7400 + _ e - mail address : _ peter3@uchicago.edu + and + d.j.   buettner + aerospace corporation + p. o. box 92957 + los angeles, ca 90009 - 2957 + _ e - mail address : _   douglas.j.buettner@aero.org   keywords : galaxies : bulge - galaxies : interactions - equation of state + pacs numbers : 95.35.+d, 95.30.qd, 95.30.cq
a direct wimp ( weakly interacting massive particle ) detector with a neutron veto system is designed to better reject neutrons.   an experimental configuration is studied in the present paper : a wimp detectors with csi(na ) target is placed inside a reactor neutrino detector.   the neutrino detector is used as a neutron veto device. the neutron background for the experimental design   has been estimated using the geant4 simulation.   the results show that the neutron background can decrease to o(0.01 ) events per year per tonne of csi(na ).   we calculate the sensitivity to spin - independent wimp - nucleon elastic scattering.   an exposure of one tonne @xmath0 year could reach a cross - section of about 3@xmath0@xmath1 pb.   @xmath2department of mathematics and physics, fujian university of technology, fuzhou 350118, china    @xmath3school of physics, nankai university, tianjin 300071, china    dark matter, neutron background, neutrino detector, csi(na )    pacs numbers : 95.35.+d, 95.55.vj, 29.40.mc
we investigate how insights from statistical physics, namely survey propagation, can improve decoding of a particular class of sparse error correcting codes.   we show that a recently proposed algorithm, time averaged belief propagation, is in fact intimately linked to a specific survey propagation for which parisi s replica symmetry breaking parameter is set to zero, and that the latter is always superior to belief propagation in the high connectivity limit.   we briefly look at further improvements available by going to the second level of replica symmetry breaking.
the electrical conductivity of graphene with a nonzero mass - gap parameter is investigated starting from the first principles of quantum electrodynamics in ( 2 + 1)-dimensional space - time at any temperature.   the formalism of the polarization tensor defined over the entire plane of complex frequency is used. at zero temperature   we reproduce the results for both real and imaginary parts of the conductivity, obtained previously in the local approximation, and generalize them taking into account the effects of nonlocality. at nonzero temperature   the exact analytic expressions for real and imaginary parts of the longitudinal and transverse conductivities of gapped graphene are derived, as well as their local limits and approximate expressions in several asymptotic regimes.   specifically, a simple local result for the real part of conductivity of gapped graphene valid at any temperature is obtained. according to our results,   the real part of the conductivity is not equal to zero for frequencies exceeding the width of the gap and goes to the universal conductivity with increasing frequency.   the imaginary part of conductivity of gapped graphene varies from infinity at zero frequency to minus infinity at the frequency defined by the gap parameter and then goes to zero with further increase of frequency.   the analytic expressions are accompanied by the results of numerical computations.   possible future generalization of the used formalism is discussed.
we study how large functional networks can grow stably under possible cascading overload failures and evaluated the maximum stable network size above which even a small - scale failure would cause a fatal breakdown of the network. employing a model of cascading failures induced by temporally fluctuating loads, the maximum stable size @xmath0 has been calculated as a function of the load reduction parameter @xmath1 that characterizes how quickly the total load is reduced during the cascade. if we reduce the total load sufficiently fast ( @xmath2 ), the network can grow infinitely. otherwise, @xmath0 is finite and increases with @xmath1. for a fixed @xmath3, @xmath0 for a scale - free network is larger than that for an exponential network with the same average degree.   we also discuss how one detects and avoids the crisis of a fatal breakdown of the network from the relation between the sizes of the initial network and the largest component after an ordinarily occurring cascading failure.
nonlinear dynamics in the fundamental interaction between a two - level atom with recoil and a quantized radiation field in a high - quality cavity is studied.   we consider the strongly coupled atom - field system as a quantum - classical hybrid with dynamically coupled quantum and classical degrees of freedom.   we show that, even in the absence of any other interaction with environment, the interaction of the purely quantum atom - field system with the external atomic degree of freedom provides the emergence of classical dynamical chaos from quantum electrodynamics.   atomic fractals with self - similar intermittency of smooth and unresolved structures are found in the exit - time scattering function.   tiny interplay between all the degrees of freedom is responsible for dynamical trapping of atoms even in a very short microcavity.   gedanken experiments are proposed to detect manifestations of atomic fractals in cavity quantum electrodynamics.
advances in nanotechnology lead to an increasing interest in how nanoparticles interact with biomembranes.   nanoparticles are wrapped spontaneously by biomembranes if the adhesive interactions between the particles and membranes compensate for the cost of membrane bending. in the last years, the cooperative wrapping of spherical nanoparticles in membrane tubules has been observed in experiments and simulations. for spherical nanoparticles  , the stability of the particle - filled membrane tubules strongly depends on the range of the adhesive particle - membrane interactions. in this article  , we show via modeling and energy minimization that elongated and patchy particles are wrapped cooperatively in membrane tubules that are highly stable for all ranges of the particle - membrane interactions, compared to individual wrapping of the particles.   the cooperative wrapping of linear chains of elongated or patchy particles in membrane tubules may thus provide an efficient route to induce membrane tubulation, or to store such particles in membranes.
single - band hubbard model at criticality of the metal - insulator transition is studied using approximations derived from parquet theory.   it is argued that only the electron - hole and interaction two - particle channels in the parquet algebra are relevant.   a scheme is proposed how to reduce the parquet equations to a manageable form the complexity of which is comparable with single - channel approximations such as the renormalized rpa. the newly derived approximation, however, contains dynamical vertex corrections, remains self - consistent at the two - particle level and allows only for integrable singularities.   a qualitatively new approach for studying two - particle singularities at zero temperature is obtained.    * international workshop on electron correlations and material properties, crete greece, june 28 - july 3, 1998 * + _ to appear in the conference proceedings, eds.   n kioussis and a. gonis, plenum press _    * strongly correlated electrons : + dynamical vertex renormalization * +    = vaclav jani + institute of physics, academy of sciences of the czech republic, + na slovance 2, cz-180 40 praha, czech republic +
we report adaptive resolution molecular dynamics simulations of a flexible linear polymer in solution.   the solvent, i.e., a liquid of tetrahedral molecules, is represented within a certain radius from the polymer s center of mass with a high level of detail, while a lower coarse - grained resolution is used for the more distant solvent.   the high resolution sphere moves with the polymer and freely exchanges molecules with the low resolution region through a transition regime.   the solvent molecules change their resolution and number of degrees of freedom on - the - fly.   we show that our approach correctly reproduces the static and dynamic properties of the polymer chain and surrounding solvent.
the determination of the ba abundance in globular cluster ( gc ) stars is a very powerful test to address several issues in the framework of multiple population scenarios.   we measured the ba content for a sample of more than 1200 stars in 15 galactic gcs, using high - resolution flames / giraffe spectra.   we found no variation in  ratios for different stellar populations within each cluster ; this means that low - mass asymptotic giant branch stars do not significantly contribute to the intracluster pollution.   + very interestingly, we obtained that the fraction of ba stars in first generation ( fg ) stars is close to the values derived for field stars ( @xmath02% ) ; on the other hand, second generation ( sg ) stars present a significant lower fraction.   an independent and successful test, based on radial velocity variations among giant stars in ngc  6121, confirms our finding : the binary fraction among fg stars is about @xmath012% to be compared with @xmath01% of sg stars.   this is an evidence that sg stars formed in a denser environment, where infant mortality of binary systems was particularly efficient.
we report on the first detection of ionospheric disturbances caused by _ short repeated _ gamma - ray bursts from the magnetar sgr j1550@xmath05418. very low frequency ( vlf ) radio wave data obtained in south america clearly show sudden amplitude and phase changes at the corresponding times of eight sgr bursts.   maximum amplitude and phase changes of the vlf signals appear to be correlated with the gamma - ray fluence. on the other hand  , vlf recovery timescales do not show any significant correlation with the fluence, possibly suggesting that the bursts spectra are not similar to each other. in summary  , the earth s ionosphere can be used as a very large gamma - ray detector and the vlf observations provide us with a new method to monitor high energy astrophysical phenomena without interruption such as earth occultation.
the hh 24 mms protostellar system was observed in the 6.9 mm continuum with a high angular resolution ( 0.5@xmath0 ).   hh 24 mms was resolved into two sources.   the separation between sources 1 and 2 is @xmath10.9@xmath0 or 360 au.   the spectral energy distribution suggests that the 6.9 mm flux is almost entirely from dust.   the 6.9 mm image and the spectrum suggest that hh 24 mms may be a protostellar binary system.   total mass including the accretion disks and the inner protostellar envelope is @xmath11.4 @xmath2.   disk masses of sources 1 and 2 are 0.6 and 0.3 @xmath2, respectively.   both sources are highly elongated.   the difference in the position angle of the two disks is @xmath145, which means that hh 24 mms is a highly misaligned protobinary system.   the misalignment suggests that turbulent fragmentation may be the formation mechanism relevant to the binary systems with a separation of a few hundreds of au, such as the hh 24 mms system.
the detachment of a semi - ordered monolayer of polystyrene microspheres adhered to an aluminum - coated glass substrate is studied using a laser - induced spallation technique.   the microsphere - substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid - body model that accounts for the inertia of the microspheres.   the estimated adhesion force is compared with estimates obtained from interferometric measurement of the out - of - plane microsphere contact resonance.   reasonable agreement is found between the two experiments.   scanning electron microscope images of detached monolayer regions reveal a unique morphology, namely, partially detached monolayer flakes composed of single hexagonal close packed crystalline domains.   this work contributes to an improved understanding of microsphere adhesion and demonstrates a unique monolayer delamination morphology.
we present a radial velocity study of the rapidly rotating b - star regulus that indicates the star is a single - lined spectroscopic binary. the orbital period   ( 40.11  d ) and probable semimajor axis ( 0.35 au ) are large enough that the system is not interacting at present.   however, the mass function suggests that the secondary has a low mass ( @xmath0 ), and we argue that the companion may be a white dwarf.   such a star would be the remnant of a former mass donor that was the source of the large spin angular momentum of regulus itself.
we study the electronic properties of an array of small metallic grains connected by tunnel junctions.   such an array serves as a model for a granular metal.   previous theoretical studies of junction arrays were based on models of quantum dissipation which did not take into account the diffusive motion of electrons within the grains.   we demonstrate that these models break down at sufficiently low temperatures : for a correct description of the screening properties of a granular metal at low energies the diffusive nature of the electronic motion within the grains is crucial.   we present both a diagrammatic and a functional integral approach to analyse the properties of junction arrays.   in particular, a new effective action is obtained which enables us to describe the array at arbitrary temperature. in the low temperature limit  , our theory yields the correct, dynamically screened coulomb interaction of a normal metal, whereas at high temperatures the standard description in terms of quantum dissipation is recovered.
we present a class of left - right symmetric models where dirac as well as majorana mass terms of neutrinos can arise at one - loop level in a scotogenic fashion : with dark matter particles going inside the loop.   we show the possibility of naturally light right handed neutrinos that can have interesting implications at neutrinoless double beta decay experiments as well as cosmology. apart from a stable dark matter candidate stabilised by a remnant @xmath0 symmetry  , one can also have a long lived kev sterile neutrino dark matter in these models.   this class of models can have very different collider signatures compared to the conventional left - right models.
we present the results of a near - infrared and x - ray study of the seyfert  2 galaxy ngc  3281.   emission from the seyfert nucleus is detected in both regions of the electromagnetic spectrum, allowing us to infer both the equivalent line of sight hydrogen column density, @xmath0 and the extinction due to dust, @xmath1magnitudes ( 90% confidence intervals ).   we infer a ratio of @xmath2 which is an order of magnitude larger than that determined along lines of sight in the milky way and discuss possible interpretations.   we consider the most plausible explanation to be a dense cloud in the foreground of both the x - ray and infrared emitting regions which obscures the entire x - ray source but only a fraction of the much larger infrared source.
we investigated the behavior of an open isotropic universe generated by a scalar field which couples with background curvature nonminimally with the coupling constant @xmath0.   in particular we focus on the situation where the initial value for the scalar field @xmath1 is greater than the critical value @xmath2=@xmath3.   the behavior is similar to an open de sitter universe with @xmath4 with a negative cosmological constant @xmath5.   it is found that the universe will collapse eventually to a singularity and thus has a finite extent in time in the future. furthermore, there are some cases which shows a rebouncing behavior before the final collapse.   pacs numbers : 98.80.cq, 98.80.hw +
we look for instanton solutions in a class of two scalar field gravity models, which includes the low energy string action in four dimensions. in models where the matter field has a potential with a false vacuum  , we find that non - singular instantons exist as long as the dilaton field found in string theory has a potential with a minimum, and provide an example of such an instanton.   the class of singular instanton solutions are also examined, and we find that depending on the parameter values, the volume factor of the euclidean region does not always vanish fast enough at the singularity to make the action finite.
we report the three - dimensional ( 3-d ) momentum - resolved soft x - ray photoemission spectroscopy of the fermi liquid lanio@xmath0. the out - of - plane and in - plane cuts of the 3-d electron- and hole - fermi surfaces ( fss ) are observed by energy- and angle- dependent photoemission measurements.   the energy bands forming the electron fs suggest an @xmath1 dependence of the imaginary part of the self - energy and a ` correlation kink'at an energy scale of 0.25 ev.   in contrast, the bands which form nesting character hole fss do not show kinks and match local density approximation calculations.   the results indicate a momentum - dependent mass renormalization, leading to electron - hole asymmetry in strongly correlated lanio@xmath0.
in response to an increasing availability of statistically rich observational data sets, the performance and applicability of traditional atmospheric cherenkov telescope analyses in the regime of systematically dominated measurement uncertainties is examined. in particular, the effect of systematic uncertainties affecting the relative normalisation of fiducial on and off - source sampling regions - often denoted as @xmath0 - is investigated using combined source analysis as a representative example case.   the traditional summation of accumulated on and off - source event counts is found to perform sub - optimally in the studied contexts and requires careful calibration to correct for unexpected and potentially misleading statistical behaviour.   more specifically, failure to recognise and correct for erroneous estimates of @xmath0 is found to produce substantial overestimates of the combined population significance which worsen with increasing target multiplicity. an alternative _ joint likelihood _   technique is introduced, which is designed to treat systematic uncertainties in a uniform and statistically robust manner.   this alternate method is shown to yield dramatically enhanced performance and reliability with respect to the more traditional approach.   gamma - ray astronomy, systematic uncertainties, combined source analysis, stacking analysis, data stacking, statistical analysis, likelihood analysis
the main goal of the icecube deep core array is to search for neutrinos of astrophysical origins.   atmospheric neutrinos are commonly considered as a background for these searches.   we show here that cascade measurements in the ice cube deep core array can provide strong evidence for tau neutrino appearance in atmospheric neutrino oscillations.   a careful study of these tau neutrinos is crucial, since they constitute an irreducible background for astrophysical neutrino detection.
the use of four lagrange points of the sun / earth system for fundamental physics experiments in space is presented.   @xmath0, @xmath1, @xmath2 and @xmath3 rotating rigidly together with the earth form a natural reference frame at the scale of the inner solar system.   the idea which is discussed in the paper considers the possibility of locating four spacecraft in the four cited lagrange points and exchanging electromagnetic pulses among them. including stations on earth, various closed paths for the pulses are possible.   time of flight measurements would be performed.   the time of flight difference between right- and left - handed circuits is proportional to the angular momentum of the sun and the detection of the effect would reach accuracies better than @xmath4 depending on the accuracy of the clock.   the four points could also be used as `` artificial pulsars '' for a relativistic positioning system at the scale of the solar system.   additional interesting possibilities include detection of a galactic gravito - magnetic field and also, using a global configuration as a zero area sagnac contour, detection of gravitational waves.   more opportunities are also mentioned.
radial - velocity measurements and sine - curve fits to the orbital velocity variations are presented for the ninth set of ten close binary systems : v395  and, hs  aqr, v449  aur, fp  boo, sw  lac, ks  peg, iw  per, v592  per, tu  umi, fo  vir.   the first three are very close, possibly detached, early - type binaries and all three require further investigation.   particularly interesting is v395  and whose spectral type is as early as b7/8 for a 0.685 day orbit binary.   ks  peg and iw  per are single - line binaries, with the former probably hosting a very low mass star.   we have detected a low - mass secondary in an important semi - detached system fo  vir at @xmath0.   the contact binary fp  boo is also a very small mass - ratio system, @xmath1.   the other contact binaries in this group are v592  per, tu  umi and the well known sw  lac.   v592  per and tu  umi have bright tertiary companions ; for these binaries, and for v395  and, we used a novel technique of the broadening functions arranged into a 2-dimensional image in phase.   the case of tu  umi turned out intractable even using this approach and we have not been able to derive a firm radial velocity orbit for this binary.   three systems of this group were observed spectroscopically before : hs  aqr, sw  lac, ks  peg.
we compute the effects of soft - gluon resummation, at the next - to - leading - logarithmic level, in the fixed - target hadroproduction cross section for prompt photons.   we find in general that the corrections to the fixed next - to - leading - order results are large for large renormalization scales, and small for small scales.   this leads to a significant reduction of the scale dependence of the results for most experimental configurations of interest.   we compare our results to the recent measurements by the e706 and ua6 collaborations.   = # 1#2#1 # 2 # 1 # 1    /#1#1/ 1    # 1     + @xmath0 cern, theoretical physics division, ch  1211 geneva 23, switzerland + @xmath1 infn, sezione di milano, italy + @xmath2 department of physics, university of durham, durham, dh1 3le, uk + @xmath3 institute for theoretical physics, state university of new york at stony brook, ny 11794 - 3840, usa    cern - th/99 - 75 + march 1999
electrical currents at the surface or edge of a topological insulator are intrinsically spin - polarized. we show that such surface / edge currents can be used to switch the orientation of a molecular magnet weakly coupled to the surface or edge of a topological insulator. for   the edge of a two - dimensional topological insulator as well as for the surface of a three - dimensional topological insulator the application of a well - chosen surface / edge current can lead to a complete polarization of the molecule if the molecule s magnetic anisotropy axis is appropriately aligned with the current direction. for a generic orientation of the molecule   a nonzero but incomplete polarization is obtained.   we calculate the probability distribution of the magnetic states and the switching rates as a function of the applied current.
a universal geometric cluster algebra over an exchange matrix @xmath0 is a universal object in the category of geometric cluster algebras over @xmath0 related by coefficient specializations.   ( following an earlier paper on universal geometric cluster algebras, we broaden the definition of geometric cluster algebras relative to the definition originally given fomin and zelevinsky. ) the universal objects are closely related to a fan @xmath1 called the mutation fan for  @xmath0. in this paper  , we consider universal geometric cluster algebras and mutation fans for cluster algebras arising from marked surfaces.   we identify two crucial properties of marked surfaces : the curve separation property and the null tangle property.   the latter property implies the former.   we prove the curve separation property for all marked surfaces except once - punctured surfaces without boundary components, and as a result we obtain a construction of the rational part of @xmath1 for these surfaces.   we prove the null tangle property for a smaller family of surfaces, and use it to construct universal geometric coefficients for these surfaces.
we present first measurements of forward jet production from @xmath0 collisions at @xmath1 gev, including transverse single spin asymmetries.   these asymmetries are expected to be sensitive to spin - correlated transverse momentum in the initial state, which is particularly interesting because it is related to orbital angular momentum in the proton.
by the topological argument that the identity matrix is surrounded by a set of separable states follows the result that if a system is entangled at thermal equilibrium for some temperature, then it presents a phase transition ( pt ) where entanglement can be viewed as the order parameter.   however, analyzing several entanglement measures in the 2-qubit context, we see that distinct entanglement quantifiers can indicate different orders for the same pt.   examples are given for different hamiltonians.   moving to the multipartite context we show necessary and sufficient conditions for a family of entanglement monotones to attest quantum phase transitions.
our main aim in this self - contained article is at the same time to detail the relationships between the resurgence and the hyperasymptotic theories, and to demonstrate how these theories can be used for an implicit resurgent function. for this purpose   we consider after stokes the question of the effective borel - resummation of an exact bohr - sommerfeld - like implicit resurgent function whose values on an explicit semi - lattice provide the zeros of the airy function.   the resurgent structure encountered resembles what one usually gets in nonlinear problems, so that the method described here is quite general.
phase randomizing processes in mesoscopic systems can be described in a phenomenological way within the landauer - bttiker formalism by attaching extra voltage probes to the sample. in this paper  , it is shown that a perturbation treatment of this idea allows for the incorporation of such effects without the need of giving up the efficiency of recursive techniques commonly used for calculating the transmission coefficients.   the technique is applied to a 4-probe ring, where a hall effect can be observed that originates from quantum interference rather than a lorentz force acting on the electrons.   the influence of inelastic scattering on both the hall resistance and the aharonov - bohm oscillations in the longitudinal resistance are examined.
the construction of initial data for black - hole binaries usually involves the choice of free parameters that define the spins of the black holes and essentially the eccentricity of the orbit.   such parameters must be chosen carefully to yield initial data with the desired physical properties. in this paper, we examine these choices in detail for the quasiequilibrium method coupled to apparent - horizon / quasiequilibrium boundary conditions.   first, we compare two independent criteria for choosing the orbital frequency, the `` komar - mass condition '' and the `` effective - potential method, '' and find excellent agreement.   second, we implement quasi - local measures of the spin of the individual holes, calibrate these with corotating binaries, and revisit the construction of _ non - spinning _ black hole binaries.   higher - order effects, beyond those considered in earlier work, turn out to be important. without those,   supposedly non - spinning black holes have appreciable quasi - local spin ; furthermore, the komar - mass condition and effective potential method agree only when these higher - order effects are taken into account.   we compute a new sequence of quasi - circular orbits for non - spinning black - hole binaries, and determine the innermost stable circular orbit of this sequence.
we show that a system of polaritons - combined atom and photon excitations - in an array of coupled cavities, under an experimental set - up usually considered in electromagnetically induced transparency, is described by the bose - hubbard model.   this opens up the possibility of using this system as a quantum simulator, allowing for the observation of quantum phase transitions and for the measurement of local properties, such as single site observables.   all the basic building blocks of the proposed setting have already been achieved experimentally, showing the feasibility of its realization in the near future.
crystalline fe@xmath0o@xmath1/nio bilayers were grown on mgo(001 ) substrates using reactive molecular beam epitaxy to investigate their structural properties and their morphology.   the film thickness either of the fe@xmath0o@xmath1 film or of the nio film has been varied to shed light on the relaxation of the bilayer system.   the surface properties as studied by x - ray photo electron spectroscopy and low energy electron diffraction show clear evidence of stoichiometric well - ordered film surfaces.   based on the kinematic approach x - ray diffraction experiments were completely analyzed. as a result the nio films grow pseudomorphic in the investigated thickness range ( up to 34 nm ) while the fe@xmath0o@xmath1 films relax continuously up to the thickness of 50 nm.   although all diffraction data show well developed laue fringes pointing to oxide films of very homogeneous thickness, the fe@xmath0o@xmath1-nio interface roughens continuously up to 1 nm root - mean - square roughness with increasing nio film thickness while the fe3o4 surface is very smooth independent on the fe@xmath0o@xmath1 film thickness.   finally, the fe@xmath0o@xmath1-nio interface spacing is similar to the interlayer spacing of the oxide films while the nio - mgo interface is expanded.
the scheme for accurate quantitative treatment of the radiation from a crystalline undulator in presence of the dechanneling and the photon attenuation is presented.   the number of emitted photons and the brilliance of electromagnetic radiation generated by ultra - relativistic positrons channeling in a crystalline undulator are calculated for various crystals, positron energies and different bending parameters.   it is demonstrated that with the use of high - energy positron beams available at present in modern colliders it is possible to generate the crystalline undulator radiation with energies from hundreds of kev up to tens of mev region.   the brilliance of the undulator radiation within this energy range is comparable to that of conventional light sources of the third generation but for much lower photon energies.
in the context of born - infeld _ determinantal _ gravity formulated in a n - dimensional spacetime with absolute parallelism, we found an exact 3-dimensional _ vacuum _ circular symmetric solution without cosmological constant consisting in a rotating spacetime with non singular behavior.   the space behaves at infinity as the conical geometry typical of 3-dimensional general relativity without cosmological constant.   however, the solution has no conical singularity because the space ends at a minimal circle that no freely falling particle can ever reach in a finite proper time.   the space is curved, but no divergences happen since the curvature invariants vanish at both asymptotic limits.   remarkably, this very mechanism also forbids the existence of closed timelike curves in such a spacetime.
we present _ suzaku _ xis observation of v2491 cyg ( nova cyg 2008 no.   2 ) obtained in quiescence, more than two years after the outburst.   the nova was detected as a very luminous source in a wide spectral range from soft to hard x - rays.   a very soft blackbody - like component peaking at 0.5 kev indicates that either we observe remaining, localized hydrogen burning on the surface of the white dwarf, or accretion onto a magnetized polar cap. in the second case,   v2491 cyg is a candidate `` soft intermediate polar ''.   we obtained the best fit for the x - ray spectra with several components : two of thermal plasma, a blackbody and a complex absorber. the later   is typical of intermediate polars.   the x - ray light - curve shows a modulation with a @xmath038 min period.   the amplitude of this modulation is strongly energy dependent and reaches maximum in the 0.82.0 kev range.   we discuss the origin of the x - ray emission and pulsations, and the likelihood of the intermediate polar scenario.
chromospherically active, spotted stars generally become redder as well as fainter when large starspots rotate into view on the stellar disc.   however, the  system ( a triple - lined system ), becomes bluer as it gets fainter.   one possible explanation is that hot, bright facular regions accompany the cool, dark photospheric spots of the active component.   the bluer flux of the hotter, inactive component does not appear to be sufficient to explain the observed behaviour.   we have begun a search for additional chromospherically active stars with a similar relation between colour and brightness, to investigate whether these relations can be explained in the same way.   our results for  are presented here, and we conclude that the faculae explanation holds also in this case.
we present the first results of the karhunen - love ( kl ) eigenmodes applied to real data of the las campanas redshift survey ( lcrs ) to simultaneously measure the values of the redshift - distortion parameter, @xmath0, the linearly extrapolated normalization, @xmath1, and the cdm shape parameter, @xmath2.   the results of our numerical likelihood analysis indicate a low value of @xmath3, a shape parameter @xmath4, and a linearly extrapolated normalization @xmath5, which are consistent with a low density universe, @xmath6.
we perform a detailed study of a specific two higgs doublet model ( 2hdm ) with a @xmath0 gauge symmetry, instead of a typical @xmath1 discrete symmetry, containing a very light gauge boson @xmath2 ( gev scale or below ). the standard model ( sm )   fermions do not carry @xmath0 charges, but induced couplings to the @xmath2 ( called the dark @xmath3 ) are generated through mixing with the sm neutral gauge bosons.   such a light @xmath2 could explain some astrophysical anomalies as well as the muon @xmath4 deviation, and has been the subject of great experimental interest.   we consider the scenario in which the @xmath5 sm - like higgs ( @xmath6 ) is the heavier scalar state, and focus on the lighter neutral state ( @xmath7 ) as well as charged higgs.   we analyze the constraints on the model from various experiments and predict novel channels to search for these higgs scalars at the lhc.   in particular, experiments looking for lepton - jets are among potentially important searches.
among the hot jupiters that transit their parent stars known to date, the two best candidates to be observed with transmission spectroscopy in the mid - infrared ( mir ) are hd189733b and hd209458b, due to their combined characteristics of planetary density, orbital parameters and parent star distance and brightness. here   we simulate transmission spectra of these two planets during their primary eclipse in the mir, and we present sensitivity studies of the spectra to the changes of atmospheric thermal properties, molecular abundances and c / o ratios.   our model predicts that the dominant species absorbing in the mir on hot jupiters are water vapor and carbon monoxide, and their relative abundances are determined by the c / o ratio. since the temperature profile plays a secondary role in the transmission spectra of hot jupiters compared to molecular abundances, future primary eclipse observations in the mir of those objects might give an insight on egp atmospheric chemistry.   we find here that the absorption features caused by water vapor and carbon monoxide in a cloud - free atmosphere, are deep enough to be observable by the present and future generation of space - based observatories, such as spitzer space telescope and james webb space telescope.   we discuss our results in light of the capabilities of these telescopes.
quantum properties of correlations have a key role in disparate fields of physics, from quantum information processing, to quantum foundations, to strongly correlated systems.   we tackle a specific aspect of the fundamental quantum marginal problem : we address the issue of deducing the global properties of correlations of tripartite quantum states based on the knowledge of their bipartite reductions, focusing on relating specific properties of bipartite correlations to global correlation properties.   we prove that strictly classical bipartite correlations may still require global entanglement and that unentangled  albeit not strictly classical  reductions may require global genuine multipartite entanglement, rather than simple entanglement. on the other hand, for three qubits, the strict classicality of the bipartite reductions rules out the need for genuine multipartite entanglement.   our work sheds new light on the relation between local and global properties of quantum states, and on the interplay between classical and quantum properties of correlations.
oscillation amplitudes are generally smaller within magnetically active regions like sunspots and plage, when compared to their surroundings. such magnetic features, when viewed in spatially - resolved powermaps, appear as regions of suppressed power due to reductions in the oscillation amplitudes. employing high spatial- and temporal - resolution observations from the dunn solar telescope ( dst ) in new mexico  , we study the power suppression in a region of evolving magnetic fields adjacent to a pore. by utilising wavelet analysis  , we study for the first time, how the oscillatory properties in this region change as the magnetic field evolves with time.   image sequences taken in the blue continuum, g - band, ca  ii  k and h@xmath0 filters were used in this study.   it is observed that the suppression found in the chromosphere occupies a relatively larger area confirming previous findings.   also, the suppression is extended to structures directly connected to the magnetic region and is found to get enhanced as the magnetic field strength increased with time.   the dependence of the suppression on the magnetic field strength is greater at longer periods and higher formation heights.   furthermore, the dominant periodicity in the chromosphere was found to be anti - correlated with increases in the magnetic field strength.
two models for the calculation of ionization cross sections by electron impact on atoms, the binary - encouter - bethe and the deutsch - mrk models, have been implemented ; they are intended to extend and improve geant4 simulation capabilities in the energy range below 1 kev.   the physics features of the implementation of the models are described, and their differences with respect to the original formulations are discussed.   results of the verification with respect to the original theoretical sources and of extensive validation with respect to experimental data are reported.   the validation process also concerns the ionization cross sections included in the evaluated electron data library used by geant4 for low energy electron transport. among the three cross section options,   the deutsch - mrk model is identified as the most accurate at reproducing experimental data over the energy range subject to test.   monte carlo, simulation, geant4, electrons, ionization.
we apply a quark interchange model to spin - dependent and exotic meson - meson scattering.   the model includes the complete set of standard quark model forces, including oge spin - orbit and tensor and scalar confinement spin - orbit.   scattering amplitudes derived assuming sho and coulomb plus linear plus hyperfine meson wavefunctions are compared. in i=2 @xmath0   we find approximate agreement with the s - wave phase shift from threshold to 1.5  gev, where we predict an extremum that is supported by the data.   near threshold we find rapid energy dependence that may reconcile theoretical estimates of small scattering lengths with experimental indications of larger ones based on extrapolation of measurements at moderate @xmath1. in psv scattering   we find that the quark - quark l@xmath2s and t forces map into l@xmath2s and t meson - meson interactions, and the p - wave l@xmath2s force is large.   finally we consider scattering in j@xmath3-exotic channels, and note that some of the `` deck effect '' mechanisms suggested as possible nonresonant origins of the @xmath4 signal are not viable in this model.   s1 @xmath5 d1 @xmath6 s0 @xmath7 p2 @xmath8 h3 @xmath9 p3 @xmath10 f3 @xmath11 p0 @xmath12 p0 @xmath12 p1 @xmath13    * abstract *
we learn multiple hypotheses for related tasks under a latent hierarchical relationship between tasks.   we exploit the intuition that for _ domain adaptation _, we wish to share classifier structure, but for _ multitask learning _, we wish to share covariance structure.   our hierarchical model is seen to subsume several previously proposed multitask learning models and performs well on three distinct real - world data sets.
we present a spectroscopic analysis of over 38,000 low - mass stars from the sloan digital sky survey ( sdss ) data release 5 ( dr5 ).   analysis of this unprecedentedly large sample confirms the previously detected decrease in the fraction of magnetically active stars ( as traced by h@xmath0 emission ) as a function of vertical distance from the galactic plane.   the magnitude and slope of this effect varies as a function of spectral type. using simple 1-d dynamical models,   we demonstrate that the drop in activity fraction can be explained by thin disk dynamical heating and a rapid decrease in magnetic activity.   the timescale for this rapid activity decrease changes according to the spectral type. by comparing our data to the simulations, we calibrate the age - activity relation at each m dwarf spectral type.   we also present evidence for a possible decrease in the metallicity as a function of height above the galactic plane.   in addition to our activity analysis, we provide line measurements, molecular band indices, colors, radial velocities, 3-d space motions and mean properties as a function of spectral type for the sdss dr5 low - mass star sample.
in this paper we shall show how to construct two new superstring theories in dimensions 12 and 16 which satisfy the lorenz symmetries in 4 dimensions after compactification but which satisfy different symmetry groups before compactification.   the arguments are also applied to supergravity theory.   we write the first few terms of these new supergravity actions.   the new supergravity actions can be expressed in terms of 3-branes and 5-branes respectively.
the wetting properties of graphene have proven controversial and difficult to assess.   the presence of a graphene layer on top of a substrate does not significantly change the wetting properties of the solid substrate, suggesting that a single graphene layer does not affect the adhesion between the wetting phase and the substrate. however, wetting experiments of water on graphene show contact angles that imply a large amount of adhesion. here, we investigate the wetting of graphene by measuring the mass of water vapor adsorbing to graphene flakes of different thickness at different relative humidities. our experiments unambiguously show that the thinnest of graphene flakes do not adsorb water, from which it follows that the contact angle of water on these flakes is @xmath0180@xmath1.   thicker flakes of graphene nanopowder, on the other hand, do adsorb water.   a calculation of the van der waals ( vdw ) interactions that dominate the adsorption in this system confirms that the adhesive interactions between a single atomic layer of graphene and water are so weak that graphene is superhydrophobic.   the observations are confirmed in an independent experiment on graphene - coated water droplets that shows that it is impossible to make liquid ` marbles'with molecularly thin graphene.
we consider a ginzburg - landau model for superconductivity with a chern - simons term added.   the flow diagram contains two charged fixed points corresponding to the tricritical and infrared stable fixed points.   the topological coupling controls the fixed point structure and eventually the region of first order transitions disappears.   we compute the critical exponents as a function of the topological coupling.   we obtain that the value of the @xmath0 exponent does not vary very much from the @xmath1 value, @xmath2.   this shows that the chern - simons term does not affect considerably the @xmath1 scaling of superconductors.   we discuss briefly the possible phenomenological applications of this model.   pacs numbers : 74.20de, 11.10hi.
ligo recently conducted its third scientific data run, s3. here   we summarize the veto and data quality studies conducted by the ligo scientific collaboration in connection with the search for binary inspiral signals in the s3 data.   ligo s interferometer channels and physical environmental monitors were monitored, and events in these channels coincident with inspiral triggers were examined.
we study the spread of stochastic sir ( susceptible @xmath0 infectious @xmath0 recovered ) epidemics in two types of structured populations, both consisting of schools and households. in each of the types,   every individual is part of one school and one household. in the _ independent partition model _, the partitions of the population into schools and households are independent of each other.   this model corresponds to the well - studied household - workplace model. in the _ hierarchical model _ which we introduce here, members of the same household are also members of the same school.   we introduce computable branching process approximations for both types of populations and use these to compare the probabilities of a large outbreak. the branching process approximation in the hierarchical model is novel and of independent interest.   we prove by a coupling argument that if all households and schools have the same size, an epidemic spreads easier ( in the sense that the number of individuals infected is stochastically larger ) in the independent partition model.   we also show by example that this result does not necessarily hold if households and/or schools do not all have the same size  .     corollary lemma proposition remark conjecture example
we investigate the gravitational collapse of rapidly rotating relativistic supermassive stars by means of a 3 + 1 hydrodynamical simulations in conformally flat spacetime of general relativity.   we study the evolution of differentially rotating supermassive stars of @xmath0 ( @xmath1 is the angular momentum and @xmath2 is the gravitational mass of the star ) from the onset of radial instability at @xmath3 ( @xmath4 is the circumferential radius of the star ) to the point where the conformally flat approximation breaks down.   we find that the collapse of the star of @xmath5, a radially unstable differentially rotating star form a black hole of @xmath6.   the main reason to prevent formation of a black hole of @xmath5 is that quite a large amount of angular momentum stays at the surface.   we also find that most of the mass density collapses coherently to form a supermassive black hole with no appreciable disk nor bar. in the absence of nonaxisymmetric deformation, the collapse of differentially rotating supermassive stars from the onset of radial instability are the promising sources of burst and quasinormal ringing waves in the laser interferometer space antenna.
we propose a 2-d computational model - system comprising a mixture of spheres and the objects of some other shapes, interacting via the _ lennard - jones _ potential.   we propose a reliable and efficient numerical algorithm to obtain void statistics.   the void distribution, in turn, determines the selective permeability across the system and bears a remarkable similarity with features reported in certain biological experiments.   + pacs : 07.05.tp, 46.70.hg, 87.16.ac + keywords : void statistics, algorithm, biological membranes, transport
we propose a new method to measure the coherence time of superconducting phase qubits based on the analysis of the magnetic - field dependent _ dc _ nonlinear andreev current across a high - resistance tunnel contact between the qubit and a dirty metal wire and derive a quantitative relation between the subgap @xmath0-@xmath1 characteristic and the internal correlation function of the qubit.   pacs numbers : 03.67.lx, 85.25.dq
we study stochastic billiards in infinite planar domains with curvilinear boundaries : that is, piecewise deterministic motion with randomness introduced via random reflections at the domain boundary.   physical motivation for the process originates with ideal gas models in the knudsen regime, with particles reflecting off microscopically rough surfaces.   we classify the process into recurrent and transient cases.   we also give almost - sure results on the long - term behaviour of the location of the particle, including a super - diffusive rate of escape in the transient case. a key step in obtaining our results is to relate our process to an instance of a one - dimensional stochastic process with asymptotically zero drift, for which we prove some new almost - sure bounds of independent interest.   we obtain some of these bounds via an application of general semimartingale criteria, also of some independent interest.   _ keywords : _ stochastic billiards ; rarefied gas dynamics ; knudsen random walk ; random reflections ; recurrence / transience ; lamperti problem ; almost - sure bounds ; birth - and - death chain.    _ ams 2000 subject classifications : _ 60j25, 60j05 ( primary ) ; 60f15, 60g17, 37d50, 82c40 ( secondary )
a parallel dispersive finite - difference time - domain ( fdtd ) method for the modeling of three - dimensional ( 3-d ) electromagnetic cloaking structures is presented in this paper.   the permittivity and permeability of the cloak are mapped to the drude dispersion model and taken into account in fdtd simulations using an auxiliary differential equation ( ade ) method.   it is shown that the correction of numerical material parameters and the slow switching - on of source are necessary to ensure stable and convergent single - frequency simulations.   numerical results from wideband simulations demonstrate that waves passing through a three - dimensional cloak experience considerable delay comparing with the free space propagations, as well as pulse broadening and blue - shift effects  .    cloak, finite - difference time - domain, material dispersion 78.20.ci, 52.35.hr, 02.70.bf
we explore the dynamics of entanglement in classically chaotic systems by considering a multiqubit system that behaves collectively as a spin system obeying the dynamics of the quantum kicked top. in the classical limit,   the kicked top exhibits both regular and chaotic dynamics depending on the strength of the chaoticity parameter  @xmath0 in the hamiltonian.   we show that the entanglement of the multiqubit system, considered for both bipartite and pairwise entanglement, yields a signature of quantum chaos. whereas bipartite entanglement is enhanced in the chaotic region, pairwise entanglement is suppressed.   furthermore, we define a time - averaged entangling power and show that this entangling power changes markedly as  @xmath0 moves the system from being predominantly regular to being predominantly chaotic, thus sharply identifying the edge of chaos.   when this entangling power is averaged over initial states, it yields a signature of global chaos.   the qualitative behavior of this global entangling power is similar to that of the classical lyapunov exponent.
we present a statistical characterization of the carbon - star to m - giant ( c / m ) ratio in the halo of m31. based on application of pseudo - filter band passes to our keck / deimos spectra we measure the -color index of 1288 stars in the giant stellar stream and in halo fields out to large distances. from this well - established narrow - band system, supplemented by v@xmath0i colors,   we find only a low number ( five in total ) of c - star candidates.   the resulting low c / m ratio of 10% is consistent with the values in the m31 disk and inner halo from the literature.   although our analysis is challenged by small number statistics and our sample selection, there is an indication that the oxygen - rich m - giants occur in similar number throughout the entire halo.   we also find no difference in the c - star population of the halo fields compared to the giant stream.   the very low c / m ratio is at odds with the observed low metallicities and the presence of intermediate - age stars at large radii.   our observed absence of a substantial carbon star population in the these regions indicates that the ( outer ) m31 halo can not be dominated by the debris of disk - like or smc - type galaxies, but rather resemble the dwarf elliptical ngc  147.
recent experiments to test bell s inequality using entangled photons and ions aimed at tests of basic quantum mechanical principles.   interesting results have been obtained and many loopholes could be closed. in this paper   we want to point out that tests of bell s inequality also play an important role in verifying atom entanglement schemes.   we describe as an example a scheme to prepare arbitrary entangled states of @xmath0 two - level atoms using a leaky optical cavity and a scheme to entangle atoms inside a photonic crystal. during the state preparation   no photons are emitted and observing a violation of bell s inequality is the only way to test whether a scheme works with a high precision or not.    *   keywords * : bell inequality tests, atom entanglement schemes, quantum computing, manipulation of decoherence - free states
the latest cms jet measurements in p - p collisions at @xmath0 = 7 tev, sensitive to small - x qcd physics, are discussed.   these include inclusive forward jet and simultaneous forward - central jet production, as well as production ratios and azimuthal angle decorrelations of jets widely separated in rapidity.
self - assembly of nanoparticles is an important tool in nanotechnology, with numerous applications including thin films, electronics, and drug delivery.   we study the deposition of ionic nanoparticles on a glass substrate both experimentally and theoretically.   our theoretical model consists of a stochastic cooperative adsorption and evaporation process on a two - dimensional lattice. by exploring the relationship between the initial concentration of nanoparticles in the colloidal solution and the density of particles deposited on the substrate  , we relate the deposition rate of our theoretical model to the concentration.
the statistical entropy of a scalar field on the warped ads@xmath0 black hole in the cosmological topologically massive gravity is calculated based on the brick - wall method, which is different from the wald s entropy formula giving the modified area law due to the higher - derivative corrections in that the entropy still satisfies the area law.   it means that the entropy for scalar excitations on this background is independent of higher - order derivative terms or the conventional brick wall method has some limitations to take into account the higher - derivative terms.
the standard approach to analyzing 16s tag sequence data, which relies on clustering reads by sequence similarity into operational taxonomic units ( otus ), underexploits the accuracy of modern sequencing technology.   we present a clustering - free approach to multi - sample illumina datasets that can identify independent bacterial subpopulations regardless of the similarity of their 16s tag sequences. using published data from a longitudinal time - series study of human tongue microbiota, we are able to resolve within standard 97% similarity otus up to 20 distinct subpopulations, all ecologically distinct but with 16s tags differing by as little as 1 nucleotide ( 99.2% similarity ).   a comparative analysis of oral communities of two cohabiting individuals reveals that most such subpopulations are shared between the two communities at 100% sequence identity, and that dynamical similarity between subpopulations in one host is strongly predictive of dynamical similarity between the same subpopulations in the other host.   our method can also be applied to samples collected in cross - sectional studies and can be used with the 454 sequencing platform.   we discuss how the sub - otu resolution of our approach can provide new insight into factors shaping community assembly.
the celeste atmospheric cherenkov detector, running until june 2004 at the thmis solar facility, has taken data on compact sources such as pulsars and blazars.   we will take stock of the experiment, in particular regarding the latest improvements of the detector simulation and data analysis.   these changes provide us with a new analysis of old data with smaller uncertainties.   we present here the evidence for a weak signal from mrk  501 in 2000 - 2001.
the zaklan model had been proposed and studied recently using the equilibrium ising model on square lattices ( sl ) by zaklan et al ( 2008 ), near the critica temperature of the ising model presenting a well - defined phase transition ; but on normal and modified apollonian networks ( ans ), andrade et al.   ( 2005, 2009 ) studied the equilibrium ising model.   they showed the equilibrium ising model not to present on ans a phase transition of the type for the 2d ising model. here  , using agent - based monte - carlo simulations, we study the zaklan model with the well - known majority - vote model ( mvm ) with noise and apply it to tax evasion on ans, to show that differently from the ising model the mvm on ans presents a well defined phase transition. to control the tax evasion in the economics model proposed by zaklan et al, mvm is applied in the neighborhood of the critical noise @xmath0 to the zaklan model. here   we show that the zaklan model is robust because this can be studied besides using equilibrium dynamics of ising model also through the nonequilibrium mvm and on various topologies giving the same behavior regardless of dynamic or topology used here.   keywords : opinion dynamics, sociophysics, majority vote, nonequilibrium  .    * nonequilibrium zaklan model on apollonian networks@xmath1 *    f. w. s. lima    _ dietrich stauffer computational physics lab _, departamento de fsica, + universidade federal do piau, 64049 - 550, teresina - pi, brazil.   +    e - mail : fwslima@gmail.com     +
a discrete boltzmann model ( dbm ) is proposed and applied to probe rayleigh - taylor ( rt ) instability in bi - component compressible flows.   the two components, whose specific heat ratios are independent, are described by two coupled discrete boltzmann equations.   two types of the force term, which are equivalent at the level of the first order accuracy, are introduced to describe the gravitational effects.   the discrete velocities for the two discrete boltzmann equations are independent. apart from its capability of a navier - stokes model describing the fluid flow, the dbm   can also be employed to probe more details of non - equilibrium manifestations, which can be expressed in mathematical forms of tensors as well as their invariants.   we investigate the global effects of the  fluctuation of translational energies " and  non - organized energy flux ", and the growth rate of the entropy of mixing in the evolution of rt instability.   it is interesting to find that, for low reynolds numbers, they show decreasing, increasing, and then decreasing trends. for high reynolds numbers, the early reducing tendency is particularly suppressed and even eliminated.   the competitive effects on non - equilibrium manifestations and growth of mixing entropy in the process are studied.   discrete boltzmann model, rayleigh - taylor instability, non - equilibrium effects, entropy of mixing
transport through molecular devices with strong coupling to a single vibrational mode is considered in the case where the vibration is damped by coupling to the environment.   we focus on the weak tunneling limit, for which a rate equation approach is valid.   the role of the environment can be characterized by a frictional damping term @xmath0 and corresponding frequency shift.   we consider a molecule that is attached to a substrate, leading to frequency - dependent frictional damping of the single oscillator mode of the molecule, and compare it to a reference model with frequency - independent damping featuring a constant quality factor @xmath1. for large values of @xmath1,   the transport is governed by tunneling between displaced oscillator states giving rise to the well - known series of the frank - condon steps, while at small @xmath1, there is a crossover to the classical regime with an energy gap given by the classical displacement energy. using realistic values for the elastic properties of the substrate and the size of the molecule, we calculate @xmath2-@xmath3 curves and find qualitative agreement between our theory and recent experiments on @xmath4 single - molecule devices.
earlier papers introduced a method of accurately estimating the angular cosmic microwave background ( cmb ) temperature power spectrum based on gibbs sampling. here   we extend this framework to polarized data.   all advantages of the gibbs sampler still apply, and exact analysis of mega - pixel polarized data sets is thus feasible.   these advantages may be even more important for polarization measurements than for temperature measurements.   while approximate methods can alias power from the larger e - mode spectrum into the weaker b - mode spectrum, the gibbs sampler ( or equivalently, exact likelihood evaluations ) allows for a statistically optimal separation of these modes in terms of power spectra. to demonstrate the method, we analyze two simulated data sets : 1 )  a hypothetical future cmbpol mission, with the focus on b - mode estimation ; and 2 )  a planck - like mission, to highlight the computational feasibility of the method
we investigate scaling of work and efficiency of a photonic carnot engine with the number of quantum coherent resources.   specifically, we consider a generalization of the `` phaseonium fuel '' for the photonic carnot engine, which was first introduced as a three - level atom with two lower states in a quantum coherent superposition by , to the case of @xmath0 level atoms with @xmath1 coherent lower levels.   we take into account atomic relaxation and dephasing as well as the cavity loss and derive a coarse grained master equation to evaluate the work and efficiency, analytically.   analytical results are verified by microscopic numerical examination of the thermalization dynamics.   we find that efficiency and work scale quadratically with the number of quantum coherent levels.   quantum coherence boost to the specific energy ( work output per unit mass of the resource ) is a profound fundamental difference of quantum fuel from classical resources.   we consider typical modern resonator set ups and conclude that multilevel phaseonium fuel can be utilized to overcome the decoherence in available systems.   preparation of the atomic coherences and the associated cost of coherence are analyzed and the engine operation within the bounds of the second law is verified.   our results bring the photonic carnot engines much closer to the capabilities of current resonator technologies.
we present new constraints on the star formation histories of the ultra - faint dwarf ( ufd ) galaxies, using deep photometry obtained with the _ hubble space telescope ( hst)_. a galaxy class recently discovered in the sloan digital sky survey, the ufds appear to be an extension of the classical dwarf spheroidals to low luminosities, offering a new front in efforts to understand the missing satellite problem.   they are the least luminous, most dark - matter dominated, and least chemically - evolved galaxies known.   our _ hst _ survey of six ufds seeks to determine if these galaxies are true fossils from the early universe.   we present here the preliminary analysis of three ufd galaxies : hercules, leo  iv, and ursa major  i. classical dwarf spheroidals of the local group exhibit extended star formation histories, but these three milky way satellites are at least as old as the ancient globular cluster m92, with no evidence for intermediate - age populations.   their ages also appear to be synchronized to within @xmath01  gyr of each other, as might be expected if their star formation was truncated by a global event, such as reionization.
it is shown how luttinger liquids may be studied using sea - bosons.   the main advantage of the sea - boson method is its ability to provide information about short - wavelength physics in addition to the asymptotics and is naturally generalisable to more than one dimension. in this article  , we solve the luttinger model and the calogero - sutherland model, the latter in the weak - coupling limit.   the anomalous exponent we obtain in the former case is identical to the one obtained by mattis and lieb.   we also apply this method to solve the two - dimensional analog of the luttinger model and show that the system is a landau fermi liquid.   then we solve the model of spinless fermions in one - dimension with long - range ( gauge ) interactions and map the wigner crystal phase of the system.   -0.5 in 6.5 in 0.0 in
based on the quantum technique of weak measurement, we propose a scheme to protect the entanglement from correlated amplitude damping decoherence.   in contrast to the results of memoryless amplitude damping channel, we show that the memory effects play a significant role in the suppression of entanglement sudden death and protection of entanglement under severe decoherence. moreover, we find that the initial entanglement could be drastically amplified by the combination of weak measurement and quantum measurement reversal even under the correlated amplitude damping channel.   the underlying mechanism can be attributed to the probabilistic nature of weak measurements.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
we use cosmic microwave background data from wmap, acbar, vsa and cbi, and galaxy power spectrum data from 2df, to constrain flat cosmologies based on the jordan  brans  dicke theory, using a markov chain monte carlo approach. using a parametrization based on @xmath0, and performing an exploration in the range   @xmath1 $ ], we obtain a @xmath2 marginalized probability bound of @xmath3, corresponding to a @xmath2 marginalized probability lower bound on the brans  dicke parameter @xmath4.
we study the multifractal analysis of a class of equicontractive, self - similar measures of finite type, whose support is an interval.   finite type is a property weaker than the open set condition, but stronger than the weak open set condition.   examples include bernoulli convolutions with contraction factor the inverse of a pisot number and self - similar measures associated with @xmath0-fold sums of cantor sets with ratio of dissection @xmath1 for integer @xmath2.   we introduce a combinatorial notion called a loop class and prove that the set of attainable local dimensions of the measure at points in a positive loop class is a closed interval.   we prove that the local dimensions at the periodic points in the loop class are dense and give a simple formula for those local dimensions.   these self - similar measures have a distinguished positive loop class called the essential class.   the set of points in the essential class has full lebesgue measure in the support of the measure and is often all but the two endpoints of the support.   thus many, but not all, measures of finite type have at most one isolated point in their set of local dimensions.   we give examples of bernoulli convolutions whose sets of attainable local dimensions consist of an interval together with an isolated point.   as well, we give an example of a measure of finite type that has exactly two distinct local dimensions.
in this paper we present a deep and homogeneous i - band selected multi - waveband catalogue in the cosmos field covering an area of about @xmath0.   our catalogue with a formal 50% completeness limit for point sources of @xmath1 comprises about 290  000 galaxies with information in 8 passbands.   we combine publicly available u, b, v, r, i, z, and k data with proprietary imaging in h band.   we discuss in detail the observations, the data reduction, and the photometric properties of the h - band data.   we estimate photometric redshifts for all the galaxies in the catalogue.   a comparison with 162 spectroscopic redshifts in the redshift range @xmath2 shows that the achieved accuracy of the photometric redshifts is with only @xmath3% outliers.   we derive absolute uv magnitudes and investigate the evolution of the luminosity function evaluated in the restframe uv ( 1500   ).   there is a good agreement between the lfs derived here and the lfs derived in the fors deep field.   we see a similar brightening of m@xmath4 and a decrease of @xmath5 with redshift.   the catalogue including the photometric redshift information is made publicly available.       galaxies : evolution  galaxies : fundamental parameters  galaxies : luminosity function  galaxies : photometry  galaxies : high - redshift
in this work we give a consistent picture of the thermodynamic properties of bosons in the mott insulating phase when loaded adiabatically into one - dimensional optical lattices.   we find a crucial dependence of the temperature in the optical lattice on the doping level of the mott insulator. in the undoped case,   the temperature is of the order of the large onsite hubbard interaction.   in contrast, at a finite doping level the temperature jumps almost immediately to the order of the small hopping parameter.   these two situations are investigated on the one hand by considering limiting cases like the atomic limit and the case of free fermions. on the other hand  , they are examined using a quasi - particle conserving continuous unitary transformation extended by an approximate thermodynamics for hardcore particles.
the archetypal system demonstrating stochastic resonance is nothing more than a threshold triggered device.   it consists of a periodic modulated input and noise. every time an output crosses the threshold the signal is recorded.   such a digitally filtered signal is sensitive to the noise intensity.   there exist the optimal value of the noise intensity resulting in the `` most '' periodic output. here, we explore properties of the non - dynamical stochastic resonance in non - equilibrium situations, i.e. when the gaussian noise is replaced by an @xmath0-stable noise. we demonstrate that non - equilibrium @xmath0-stable noises, depending on noise parameters, can either weaken or enhance the non - dynamical stochastic resonance.
the contribution of crossed gluon fields in flux tubes connecting quarks to the proton spin is calculated.   the calculations are performed following non - perturbative heisenberg s quantization technique. in our approach a proton   is considered as consisting of three quarks connected by three flux tubes.   the flux tubes contain colour longitudinal electric and transversal electric and magnetic fields.   the longitudinal electric field causes the interaction forces between quarks.   the quantum superposition of the transversal fields causes the appearance of the angular momentum density.   the dimensionless relation between the angular momentum and the mass of the gluon fields is obtained. the contribution to proton spin from rotating quarks and flux tubes connecting quarks   is estimated.   simple numerical relation between the proton mass, the speed of light and the proton radius, which is of the same order as the planck constant, is discussed.
i review here some of the physics we are learning and expect to learn in the near future through the observation of cosmic rays.   the study of cosmic rays involves a combination of data from accelerators, ground arrays, atmospheric fluorescence detectors and balloon and satellite experiments.   i will discuss the data of the pierre auger observatory, pamela, atic and fst among other experiments.
restricted boltzmann machines ( rbm ) have attracted a lot of attention of late, as one the principle building blocks of deep networks.   training rbms remains problematic however, because of the intractibility of their partition function.   the maximum likelihood gradient requires a very robust sampler which can accurately sample from the model despite the loss of ergodicity often incurred during learning.   while using parallel tempering in the negative phase of stochastic maximum likelihood ( sml - pt ) helps address the issue, it imposes a trade - off between computational complexity and high ergodicity, and requires careful hand - tuning of the temperatures. in this paper  , we show that this trade - off is unnecessary.   the choice of optimal temperatures can be automated by minimizing average return time ( a concept first proposed by @xcite ) while chains can be spawned dynamically, as needed, thus minimizing the computational overhead.   we show on a synthetic dataset, that this results in better likelihood scores.
the pre - neutron - emission mass distributions for reaction @xmath0th(n, f ) up to 60 mev are systematically studied with an empirical fission potential model.   the energy dependences of the peaks and valleys of the pre - neutron - emission mass distributions are described by the exponential expressions based on the newly measured data.   the energy dependence of evaporation neutrons before scission, which plays a crucial role for the reasonable description of the mass distribution, is also considered.   both the double - humped and triple - humped shape of the measured pre - neutron - emission mass distributions for reaction @xmath0th(n, f ) are reasonably well reproduced at incident energies up to 60 mev.   the mass distributions at unmeasured energies and the critical energies at which the humped pre - neutron - emission mass distributions are transformed into each other are also predicted.   @xmath0th(n, f ) ; pre - neutron - emission mass distribution ; evaporation neutron ; fission potential    24.75.+i ; 25.85.ec
particle production in the forward region of heavy - ion collisions is shown to be due to parton recombination without shower partons.   the regeneration of soft partons due to momentum degradation through the nuclear medium is considered.   the degree of degradation is determined by fitting the @xmath0 ratio.   the data at @xmath1 gev and @xmath2 from brahms on the @xmath3 distribution of average charged particles are well reproduced.   large proton - to - pion ratio is predicted.   the particles produced at any @xmath3 should have no associated particles above background to manifest any jet structure.   0.5 cm pacs numbers : 25.75.dw   .75 cm * rudolph c. hwa@xmath4 and c.  b.  yang@xmath5 *.5 cm @xmath4institute of theoretical science and department of physics + university of oregon, eugene, or 97403 - 5203, usa + @xmath6institute of particle physics, hua - zhong normal university, wuhan 430079, p.  r.  china   .5 cm
a system of coherently - driven two - level atoms is analyzed in presence of two independent stochastic perturbations : one due to collisions and a second one due to phase fluctuations of the driving field.   the behaviour of the quantum interference induced by the collisional noise is considered in detail.   the quantum - trajectory method is utilized to reveal the phase correlations between the dressed states involved in the interfering transition channels.   it is shown that the quantum interference induced by the collisional noise is remarkably robust against phase noise.   this effect is due to the fact that the phase noise, similarly to collisions, stabilizes the phase - difference between the dressed states.
an efficient implementation of the nonequilibrium green function ( negf ) method combined with the density functional theory ( dft ) using localized pseudo - atomic orbitals ( paos ) is presented for electronic transport calculations of a system connected with two leads under a finite bias voltage. in the implementation,   accurate and efficient methods are developed especially for evaluation of the density matrix and treatment of boundaries between the scattering region and the leads.   equilibrium and nonequilibrium contributions in the density matrix are evaluated with very high precision by a contour integration with a continued fraction representation of the fermi - dirac function and by a simple quadrature on the real axis with a small imaginary part, respectively.   the hartree potential is computed efficiently by a combination of the two dimensional fast fourier transform ( fft ) and a finite difference method, and the charge density near the boundaries is constructed with a careful treatment to avoid the spurious scattering at the boundaries.   the efficiency of the implementation is demonstrated by rapid convergence properties of the density matrix.   in addition, as an illustration, our method is applied for zigzag graphene nanoribbons, a fe / mgo / fe tunneling junction, and a lamno@xmath0srmno@xmath1 superlattice, demonstrating its applicability to a wide variety of systems.
in this work we analyze the temporal dynamics of a system comprising an optical cavity filled with a nonlinear kerr medium, whose frequency is allowed to change during time evolution. by exactly solving the corresponding time - dependent anharmonic - oscillator hamiltonian  , we demonstrate that squeezed coherent - state superpositions can be generated within the optical cavity.   moreover, we show that the squeezing degree of the produced states may be tuned by properly controlling the frequency shift of the cavity, a feature that might lead to interesting studies in the field of quantum state engineering.
applicability of the concept of financial log - periodicity is discussed and encouragingly verified for various phases of the world stock markets development in the period 2000 - 2010. in particular, a speculative forecasting scenario designed in the end of 2004, that properly predicted the world stock market increases in 2007, is updated by setting some more precise constraints on the time of duration of the present long - term equity market bullish phase.   a termination of this phase is evaluated to occur in around november 2009. in particular, on the way towards this dead - line, a spring - summer 2008 increase is expected. on the precious metals market   a forthcoming critical time signal is detected at the turn of march / april 2008 which marks a tendency for at least a serious correction to begin.    in the present extended version some predictions for the future oil price are incorporated. in particular a serious correction on this market is expected in the coming days.   keywords : complex systems, financial markets, fundamental laws of nature    1.0 cm    _ e - mail address : stanislaw.drozdz@ifj.edu.pl_
strong - field electrodynamics ( sfe ) is maxwell theory with a certain lorentz - covariant ohm s law which uses only the electromagnetic degrees of freedom.   we show that sfe is _ semi - dissipative _ : while the dissipation rate of the electromagnetic energy is non - negative, it can be exactly zero for non - trivial electromagnetic fields.   it appears that sfe is well - defined for arbitrary electromagnetic fields.   it should be possible to calculate the dissipative pulsar magnetosphere and resolve the magnetic separatrix using sfe.   we show that sfe reduces to force - free electrodynamics ( ffe ) in the large conductivity limit. in the regions where the ideal ffe 4-current is space - like  , sfe predicts small dissipative corrections. in the regions where the ideal ffe 4-current is time - like  , sfe predicts a zero correction.   this indicates that bright pulsars radiate primarily from the magnetic separatrix.
for polarization experiments involving photon counting we introduce a quasi - deterministic eigenstate transition model of the analyzer process.   distributions accumulated one photon at a time, provide a deterministic explanation for the law of malus.   we combine this analyzer model with causal polarization coupling to calculate photon - photon correlations, one photon pair at a time.   the calculated correlations exceed the bell limits and show excellent agreement with the measured correlations of [ a. aspect, p. grangier and g. rogers, phys.   rev.   lett.   49 91 ( 1982 ) ].   we discuss why this model exceeds the bell type limits.    1.0 in.5 in
the detection of @xmath0-rays  from the source hessj1745@xmath1290 in the galactic center ( gc ) region with the h.e.s.s.   array of cherenkov telescopes in 2004 is presented.   after subtraction of the diffuse @xmath0-ray  emission from the gc  ridge, the source is compatible with a point - source with spatial extent less than @xmath2 ( 95% cl ).   the measured energy spectrum above 160  gev is compatible with a power - law with photon index of @xmath3 and no significant flux variation is detected.   it is finally found that the bulk of the vhe emission must have non - dark - matter origin.
topological singularities occur in a broad range of physical systems, including collapsing stars and pinching fluid interfaces.   they are important for being able to concentrate energy into a small region.   underwater air bubbles in particular appear in many practical applications, including new technologies to reduce skin drag on cargo ships.   previous theories show that just before an air bubble pinches off, the neck looks like a cylinder at its very smallest point.   unusually, however, the neck approaches this shape so gradually that the theoretical cylinder solution is not reached in practice ; the singularity spends its entire lifetime in a transient phase.   therefore, in order to understand the evolution, we study the transient effects in detail. this paper details the simulation results of bubbles with initial conditions far from the cylindrical solution : squat, up  down asymmetric neck shapes, with imposed vertical flow.   we find that the asymmetry is transient : the neck quickly shifts vertically to become up  down symmetric.   importantly, we find that the resulting symmetric singularity is a blend of the initial top and bottom sides, with a weighting factor that is tunable by adjusting the airflow through the neck.   this effect should have implications for the later stages of evolution, including the generation of satellite bubbles and the formation of the worthington jet.   physics department and the james franck institute, university of chicago, chicago il 60637
we present the analysis on the quadrupole phases of the internal linear combination map, ilc(i ) and ( iii ) derived by the team ( 1 and 3-year data release ).   this approach allows us to see the global trend of non - gaussianity of the quadrupoles for the ilc(iii ) map through phase correlations with the foregrounds.   significant phase correlations is found in between the ilc(iii ) quadrupole and the foregrounds phases for k - w band : the phases of the ilc(iii ) quadrupole @xmath0, @xmath1 and those of the foregrounds at k - w bands @xmath2, @xmath3 display significant symmetry : @xmath4, which is a strong indication that the morphology of the ilc(iii ) quadrupole is mere reflection of that the foreground quadrupole through coupling. to clarify this issue we exploit the symmetry of the cmb power, which is invariant under permutation of the index @xmath5. by simple rotation of the ilc(iii )   phases with the same angle we reach the phases of foreground quadrupole.   we discuss possible sources of phase correlation and come to the conclusion that the phases of the ilc(iii ) quadrupole reflect most likely systematic effects such as changing of the gain factor for the 3-year data release with respect to the 1-year, rather than manifestation of the primordial non - gaussianity.   cosmology : cosmic microwave background   observations  methods : data analysis
we have examined tev scale effects of extra spatial dimensions through the processes @xmath0 where @xmath1.   these processes have been treated in a photon - proton collision via the main reaction @xmath2 at the lhc.   we have employed equivalent photon approximation for incoming photon beams and performed statistical analysis for various forward detector acceptances.
we investigate the thermal evolution of comet 67p / churyumov - gerasimenko s subsurface in the seth@xmath001 region, where active pits have been observed by the esa / rosetta mission.   our simulations show that clathrate destabilization and amorphous ice crystallization can occur at depths corresponding to those of the observed pits in a timescale shorter than 67p / churyumov - gerasimenko s lifetime in the comet s activity zone in the inner solar system.   sublimation of crystalline ice down to such depths is possible only in the absence of a dust mantle, which requires the presence of dust grains in the matrix small enough to be dragged out by gas from the pores.   our results are consistent with both pits formation via sinkholes or subsequent to outbursts, the dominant process depending on the status of the subsurface porosity.   a sealed dust mantle would favor episodic and disruptive outgassing as a result of an increasing gas pressure in the pores, while a high porosity should allow the formation of large voids in the subsurface due to the continuous escape of volatiles.   we finally conclude that the subsurface of 67p / churyumov - gerasimenko is not uniform at a spatial scale of @xmath1100200  m.
geometric quantum discord is a well - defined measure of quantum correlation if schatten 1-norm ( trace norm ) is adopted as a distance measure. here  , we analytically investigate the dynamical behavior of the 1-norm geometric quantum discord under the effect of decoherence. by starting from arbitrary bell - diagonal mixed states under markovian local noise  , we provide the decays of the quantum correlation as a function of the decoherence parameters.   in particular, we show that the 1-norm geometric discord exhibits the possibility of double sudden changes and freezing behavior during its evolution. for nontrivial bell - diagonal states under simple markovian channels,   these are new features that are in contrast with the schatten 2-norm ( hilbert - schmidt ) geometric discord.   the necessary and sufficient conditions for double sudden changes as well as their exact locations in terms of decoherence probabilities are provided.   moreover, we illustrate our results by investigating decoherence in quantum spin chains in the thermodynamic limit.
the massive spin-2 quantum gauge theory previously developed is applied to calculate gravitational bremsstrahlung.   it is shown that this theory is unique and free from defects. in particular, there is no strong coupling if the graviton mass becomes small.   the cross sections go over smoothly into the ones of the massless theory in the limit of vanishing graviton mass.   the massless cross sections are calculated for the full tensor theory.
we propose a scheme to modulate the entanglement between two oscillators separated in space via the squeezing cavity field generated by the optical parametric amplifier instead of injecting the squeezing field directly with the assistance of coulomb interaction.   we show that the coulomb interaction between the oscillators is the essential reason for the existence of entanglement. due to the gain of the optical parametric amplifier and the phase of the pump driving the optical parametric amplifier   can simultaneously modulate the squeezing cavity field, the radiation pressure interaction between the cavity field and the oscillator is modulated accordingly.   we find that there is competing effect between the radiation pressure interaction and the coulomb interaction for the oscillator which these two interactions act on simultaneously.   therefore, the modulation of entanglement can be achieved with the assistance of coulomb interaction.   the results of numerical simulation show that the present scheme has stronger robustness against the temperature of environment compared with previous schemes in experimentally feasible regimes.
we present the idea of searching for x - rays as a signature of the mechanism inducing the spontaneous collapse of the wave function. such a signal is predicted by the continuous spontaneous localization theories, which are solving the `` measurement problem '' by modifying the schrdinger equation.   we will show some encouraging preliminary results and discuss future plans and strategy.   + pacs : 29.30.kv collapse models ; 32.30.rj x - ray measurements    example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
quantum cosmology offers a unique stage to address questions of time related to its underlying ( and perhaps truly quantum dynamical ) meaning as well as its origin.   some of these issues can be analyzed with a general scheme of quantum cosmology, others are best seen in loop quantum cosmology.   the latter s status is still incomplete, and so no full scenario has yet emerged.   nevertheless, using properties that have a potential of pervading more complicated and realistic models, a vague picture shall be sketched here.   it suggests the possibility of deriving a beginning within a beginningless theory, by applying cosmic forgetfulness to an early history of the universe.    a momentous arrow of time + martin bojowald + institute for gravitation and the cosmos, + the pennsylvania state university, + 104 davey lab, university park, pa 16802, usa +
optical and electrical characteristics of algaas lasers with separate confinement heterostructures are modeled by using synopsys s sentaurus tcad and open source software for semi - automatic data analysis of large collections of data.   the effects of doping in all laser layers are investigated with the aim to achieve optimal characteristics of the devise.   the results are compared with these obtained for real lasers produced at polyus research institute in moscow, showing that a significant improvement can be achieved, in particular an increase in optical efficiency ( up to over 70 % ) by careful control of type and level of doping through out the entire structure.   = 3.00ex
the existence of planets born in environments highly perturbed by a stellar companion represents a major challenge to the paradigm of planet formation. in numerical simulations,   the presence of a close binary companion stirs up the relative velocity between planetesimals, which is fundamental in determining the balance between accretion and erosion.   however, the recent discovery of circumbinary planets by _ kepler _ establishes that planet formation in binary systems is clearly viable.   we perform n - body simulations of planetesimals embedded in a protoplanetary disk, where planetesimal phasing is frustrated by the presence of stochastic torques, modeling the expected perturbations of turbulence driven by the magnetorotational instability ( mri ).   we examine perturbation amplitudes relevant to dead zones in the midplane ( conducive to planet formation in single stars ), and find that planetesimal accretion can be inhibited even in the outer disk ( 4 - 10 au ) far from the central binary, a location previously thought to be a plausible starting point for the formation of circumbinary planets.
if the efficiency for producing @xmath0-rays is the same in short duration ( @xmath1 s ) gamma - ray bursts ( grbs ) as in long duration grbs, then the average kinetic energy of short grbs must be @xmath2 times less than that of long grbs.   assuming further that the relativistic shocks in short and long duration grbs have similar parameters, we show that the afterglows of short grbs will be on average 1040 times dimmer than those of long grbs.   we find that the afterglow of a typical short grb will be below the detection limit ( @xmath3 ) of searches at radio frequencies  . the afterglow would be difficult to observe also in the optical, where we predict @xmath4 a few hours after the burst  . the radio and optical afterglow would be even fainter if short grbs occur in a low - density medium, as expected in ns  ns and ns  bh merger models.   the best prospects for detecting short - grb afterglows are with early ( @xmath5 day ) observations in x - rays.    3
vimos is a wide - field imager and spectrograph mounted on ut3 at the vlt, whose fov consists of four 7x8 quadrants. here   we present the measurements of total transmission profiles   i.e. the throughput of telescope + instrument  for the broad band filters   u, b, v, r, i, and z for each of its four quadrants. those measurements can also be downloaded from the public vimos web - page.   the transmission profiles are compared with previous estimates from the vimos consortium.
we present preliminary results using overlap fermions for the charmonium spectrum, in particular for hyperfine splitting.   simulations are performed on @xmath0 lattices, with wilson gauge action at @xmath1.   depending on how the scale is set, we obtain 104(5 )  mev ( using @xmath2 ) or 88(4 )  mev ( using @xmath3=0.5  fm ) for the hyperfine splitting.
a bootstrap procedure for functional time series is proposed which exploits a general vector autoregressive representation of the time series of fourier coefficients appearing in the karhunen - love expansion of the functional process.   a double sieve - type bootstrap method is developed which avoids the estimation of process operators and generates functional pseudo - time series that appropriately mimic the dependence structure of the functional time series at hand.   the method uses a finite set of functional principal components to capture the essential driving parts of the infinite dimensional process and a finite order vector autoregressive process to imitate the temporal dependence structure of the corresponding vector time series of fourier coefficients. by allowing the number of functional principal components as well as the autoregressive order used to increase to infinity ( at some appropriate rate ) as the sample size increases,   a basic bootstrap central limit theorem is established which shows validity of the bootstrap procedure proposed for functional finite fourier transforms.   some numerical examples illustrate the good finite sample performance of the new bootstrap method proposed.   = cmr8 at 8.   truept 2u^n+12 2n+12 _   ht_h   p + r_*^+ ii ||||         notation definition     22.25 cm 17.5 cm    plus 1pt plus 2pt minus 2pt    = cmss12 = cmr7
we review what has been learned recently using simulations about the evolution of globular clusters. while simulations of star clusters have become more realistic, and now include the evolution of single and binary stars, the prospect of reaching large enough @xmath0 is still a distant one.   nevertheless more restricted kinds of simulations have recently brought valuable progress for certain problems of current observational interest, including the origin and structure of tidal tails of globular clusters.   in addition, such simulations have forced us to rethink some basic aspects of stellar dynamics, including, in particular, the process of escape.   finally we turn to faster, approximate methods for studying star cluster dynamics, where the role of simulations is one of calibration.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
the effect of environment on the circumgalactic medium ( cgm ) is investigated through a comparison of absorption line data in the virgo cluster and the field.   this letter uses the first systematic survey of background qsos in and around the virgo cluster and large existing surveys of galaxies at low redshift. while previous studies found denser gas ( higher equivalent width ) closer to a galaxy ( lower impact parameter )  , this correlation disappears in the virgo environment.   in addition, the covering fraction of the cgm is lower in the cluster environment than in the circumcluster environment and field.   the results indicate that the cgm is suppressed for cluster galaxies while galaxies in the circumcluster environment have abundant cgm.   the truncation of the cgm may result in the quenching of star formation through starvation.   our results also show that cgm surveys must consider the role of environment.
using the green s function formalism, an _ ab initio _ theory for band structures of crystals is derived starting from the hartree - fock approximation.   it is based on the algebraic diagrammatic construction scheme for the self - energy which is formulated for crystal orbitals  ( co - adc ). in this approach, the poles of the green s function are determined by solving a suitable hermitian eigenvalue problem.   the method is not only applicable to the outer valence and conduction bands, it is also stable for inner valence bands where strong electron correlations are effective.   the key to the proposed scheme is to evaluate the self - energy in terms of wannier orbitals before transforming it to a crystal momentum representation.   exploiting the fact that electron correlations are mainly local, one can truncate the lattice summations by an appropriate configuration selection scheme.   this yields a flat configuration space ; i.e., its size scales only linearly with the number of atoms per unit cell for large systems and, under certain conditions, the computational effort to determine band structures also scales linearly. as a first application of the new formalism  , a lithium fluoride crystal has been chosen.   a minimal basis set description is studied, and a satisfactory agreement with previous theoretical and experimental results for the fundamental band gap and the width of the f@xmath0  valence band complex is obtained.
lacob1 is a nearby ob association in its final stage of star formation.   while the member stars suggest an expansion time scale of tens of myr, the latest star formation episode, as manifested by the existence of massive and pre - main sequence stars, took place no more than a few myr ago.   the remnant molecular clouds in the region provide evidence of starbirth triggered by massive stars.
distributional sources of matter on codimension - two and higher branes are only well - defined as regularized objects.   nevertheless, intuition from effective field theory suggests that the low - energy physics on such branes should be independent of any high - energy regularization scheme. in this paper  , we address this issue in the context of a scalar field model where matter fields ( the standard model ) living on such a brane interact with bulk fields ( gravity ).   the low - energy effective theory is shown to be consistent and independent of the regularization scheme, provided the brane couplings are renormalized appropriately at the classical level.   we perform explicit computations of the classical renormalization group flows at tree and one - loop level, demonstrate that the theory is renormalizable against codimension - two divergences, and extend the analysis to several physical applications such as electrodynamics and brane localized kinetic terms.
we report on the implementation of a novel optical setup for generating high - resolution customizable potentials to address ultracold bosonic atoms in 2d.   two key features are developed for this purpose.   the customizable potential is produced with a direct image of a spatial light modulator, conducted with an in - vacuum imaging system of high numerical aperture.   custom potentials are drawn over an area of @xmath0 m with a spot - size of 1  @xmath1 m.   the second development is a two - dimensional planar trap for atoms with an aspect ratio of 900 and spatial extent of rayleigh range 1.6  @xmath2  1.6  mm, providing near - ballistic in - planar movement.   we characterize the setup and present a brief catalog of experiments to highlight the versatility of the system.
in may 2008, the antares collaboration has completed the construction of the first deep sea neutrino telescope in the northern hemisphere.   antares is a 3d array of 900 photomultipliers held in the sea by twelve mooring lines anchored at a depth of 2500 m in the mediterranean sea 40 km off the southern french coast.   the detection principle is based on the observation of cerenkov light induced by charged particles produced in neutrino interactions in the matter surrounding the detector.
we propose to measure the weak cosmic shear using the spatial derivatives of the galaxy surface brightness field.   the measurement should be carried out in fourier space, in which the point spread function ( psf ) can be transformed to a desired form with multiplications, and the spatial derivatives can be easily measured.   this method is mathematically well defined regardless of the galaxy morphology and the form of the psf, and involves simple procedures of image processing.   furthermore, with high resolution galaxy images, this approach allows one to probe the shape distortions of galaxy substructures, which can potentially provide much more independent shear measurements than the ellipticities of the whole galaxy.   we demonstrate the efficiency of this method using computer - generated mock galaxy images.       cosmology : theory - weak lensing
we consider electronic transport through laterally parallel double open quantum dots embedded in a quantum wire in a perpendicular magnetic field.   the coupling modes of the dots are tunable by adjusting the strength of a central barrier and the applied magnetic field.   probability density and electron current density are calculated to demonstrate transport effects including magnetic blocking, magnetic turbulence, and a hole - like quasibound state feature.   fano to dip line - shape crossover in the conductance is found by varying the magnetic field.
in this paper, we prove that there is a weakly universal cellular automaton on the pentagrid with two states.   this paper improves in some sense a previous result with three states.   both results make use of _  la moore _ neighbourhood  . however, the result with three states is rotation invariant while that with two states is not. in both cases, at each step of the computation, the set of non quiescent states has always infinitely many cycles.
a micron - precision optical alignment system ( oasys ) for the phenix muon tracking chambers is developed. to ensure the required mass resolution of vector meson detection, the relative alignment between three tracking station chambers   must be monitored with a precision of 25@xmath0 m.   the oasys is a straightness monitoring system comprised of a light source, lens and ccd camera, used for determining the initial placement as well as for monitoring the time dependent movement of the chambers on a micron scale.   tracking chamber, alignment, optics, imaging 29.40.gx, 07.05.pj, 07.60.-j, 42.62.hk
type ib / c supernovae ( sne ib / c ) mark the deaths of hydrogen - deficient massive stars.   the evolutionary scenarios for sne ib / c progenitors involve many important physical processes including mass loss by winds and its metallicity dependence, stellar rotation, and binary interactions.   this makes sne ib / c an excellent test bed for stellar evolution theory.   we review the main results of evolutionary models for sn ib / c progenitors available in the literature and their confrontation with recent observations.   we argue that the nature of sn ib / c progenitors can be significantly different for single and binary systems, and that binary evolution models can explain the ejecta masses derived from sn ib / c light curves, the distribution of sn ib / c sites in their host galaxies, and the optical magnitudes of the tentative progenitor candidate of iptf13bvn.   we emphasize the importance of early - time observations of light curves and spectra, accurate measurements of helium mass in sn ib / c ejecta, and systematic studies about the metallicity dependence of sn ib / c properties, to better constrain theories.   stars : evolution  binaries : general  supernovae : general  stars : massive  stars : wolf - rayet
we explore the orbital dynamics of a realistic three dimensional model describing the properties of a disk galaxy with a spherically symmetric central dense nucleus and a triaxial dark matter halo component.   regions of phase space with regular and chaotic motion are identified depending on the parameter values for triaxiality of the dark matter halo and for breaking the rotational symmetry.   the four dimensional poincar map of the three degrees of freedom system is analysed by a study of its restriction to various two dimensional invariant subsets of its domain.   = 1    hamiltonian systems  ordered and chaotic motion   symplectic map of dimension four
the estimation of the correlation between time series is often hampered by the asynchronicity of the signals.   cumulating data within a time window suppresses this source of noise but weakens the statistics.   we present a method to estimate correlations without applying long time windows.   we decompose the correlations of data cumulated over a long window using decay of lagged correlations as calculated from short window data.   this increases the accuracy of the estimated correlation significantly and decreases the necessary efforts of calculations both in real and computer experiments.   05.45.tp, 06.30.ft, 05.40.ca, 89.65.gh
we theoretically investigate the quantum noise properties of the pulse pumped high gain fiber optical parametric amplifiers ( fopa ) by using the bogoliubov transformation in multi - frequency modes to describe the evolution of the non - degenerate signal and idler twin beams.   the results show that the noise figure of the fopa is generally greater than the 3 db quantum limit unless the joint spectral function is factorable and the spectrum of the input signal well matches the gain spectrum in the signal band  . however, the intensity difference noise of the twin beams, which weakly depends on the joint spectral function, can be significantly less than the shot - noise limit when the temporal modes of the pump and the input signal are properly matched.   moreover, to closely resemble the real experimental condition, the quantum noise of twin beams generated from a broadband fopa is numerically studied by taking the various kinds of experimental imperfections into account.   our study is not only useful for developing a compact fiber source of twin beams, but also helpful for understanding the quantum noise limit of a pulse pumped fopa in the fiber communication system.
we present hybrid maps of the a and b  images of 0957 + 561 from each of four sessions of 6 cm vlbi observations that span the six - year interval 19871993.   the inner- and outer - jets are clearly detected and confirm the structures reported previously.   there is no evidence of change in the separation between the core and inner - jet components, so the prospect of measuring the time delay using differential proper motions is not promising. the flux density in the core of each image peaked between 1989 and 1992. from the variation in these flux densities,   we obtain a time - delay estimate of @xmath0.    _ to appear in the astronomical journal, 1995.12.   _    _ submitted 1995.07.06, accepted 1995.08.17. _
we provide a systematic analysis of a prototypical nonlinear oscillator system respecting @xmath0-symmetry i.e., one of them has gain and the other an equal and opposite amount of loss. starting from the linear limit of the system, we extend considerations to the nonlinear case for both soft and hard cubic nonlinearities identifying symmetric and anti - symmetric breather solutions, as well as symmetry breaking variants thereof.   we propose a reduction of the system to a schrdinger type @xmath0-symmetric dimer, whose detailed earlier understanding can explain many of the phenomena observed herein, including the @xmath0 phase transition  . nevertheless, there are also significant parametric as well as phenomenological potential differences between the two models and we discuss where these arise and where they are most pronounced. finally, we also provide examples of the evolution dynamics of the different states in their regimes of instability.
here we have studied first and second - order intertwining approach to generate isospectral partner potentials of position - dependent ( effective ) mass schrdinger equation.   the second - order intertwiner is constructed directly by taking it as second order linear differential operator with position depndent coefficients and the system of equations arising from the intertwining relationship is solved for the coefficients by taking an ansatz. a complete scheme for obtaining general solution is obtained which is valid for any arbitrary potential and mass function.   the proposed technique allows us to generate isospectral potentials with the following spectral modifications : ( i ) to add new bound state(s ), ( ii ) to remove bound state(s ) and ( iii ) to leave the spectrum unaffected. to explain our findings with the help of an illustration, we have used point canonical transformation ( pct ) to obtain the general solution of the position dependent mass schrodinger equation corresponding to a potential and mass function.   it is shown that our results are consistent with the formulation of type a @xmath0-fold supersymmetry @xcite for the particular case @xmath1 and @xmath2 respectively.
a novel model of thermal regulation of homoeothermic animals has been implemented.   the model is based on a non - equilibrium thermodynamic approach which introduces entropy balance and the rate of entropy generation as a formulation of the second law.   the model explains linear correlation between an animal s skin and environment temperatures using the first principles and demonstrates the role of blood circulation in the thermoregulation of homoeothermic animals.
we prove for an infinite array of globally coupled overdamped anharmonic oscillators subject to additive gaussian white noise the existence of a well - behaved critical manifold in the parameter space which separates a symmetric phase from a symmetry broken phase.   given two of the system parameters there is an unique critical value of the third.   the proof exploits that the critical control parameter @xmath0 is bounded by its limit values for weak and for strong noise. in these limits the mechanism of symmetry breaking differs. for weak   noise the distribution is gaussian and the symmetry is broken as the whole distribution is shifted in either the positive or the negative direction. for strong noise   there is a symmetric double - peak distribution and the symmetry is broken as the weights of the peaks become different.   we derive an ordinary differential equation whose solution describes the critical manifold. using a series ansatz to solve this differential equation we determine the critical manifold for weak and for strong noise and compare it to numerical results.   we derive analytic expressions for the order parameter and the susceptibility close to the critical manifold.
we discuss the origin of the runaway early b - type star hd271791 and show that its extremely high velocity ( @xmath0 ) can not be explained within the framework of the binary - supernova ejection scenario.   instead, we suggest that hd271791 attained its peculiar velocity in the course of a strong dynamical encounter between two hard massive binaries or via an exchange encounter between a hard massive binary and a very massive star, formed through runaway mergers of ordinary massive stars in the dense core of a young massive star cluster.
we introduce the notion of @xmath0-cosupport as a new tool for the stable module category of a finite group scheme. in the case of a finite group,   we use this to give a new proof of the classification of tensor ideal localising subcategories. in a sequel to this paper,   we carry out the corresponding classification for finite group schemes.
we present an effective theory describing the low - energy properties of an interacting 2d electron gas at large non - integer filling factors @xmath0. assuming that the interaction is sufficiently weak, @xmath1  , we integrate out all the fast degrees of freedom, and derive the effective hamiltonian acting in the fock space of the partially filled landau level only.   this theory enables us to find two energy scales controlling the electron dynamics at energies less than @xmath2.   the first energy scale, @xmath3, appears in the one electron spectral density as the width of a pseudogap.   the second scale, @xmath4, is parametrically larger ; it characterizes the exchange - enhanced spin splitting and the thermodynamic density of states.
high - resolution x - ray spectra of high - mass stars and low - mass t - tauri stars obtained during the first year of the _ chandra _ mission are providing important clues about the mechanisms which produce x - rays on very young stars. for @xmath0  pup   ( o4  if ) and @xmath0  ori ( o9.5  i ), the broad, blue - shifted line profiles, line ratios, and derived temperature distribution suggest that the x - rays are produced throughout the wind via instability - driven wind shocks.   for some less luminous ob stars, like @xmath1  ori  c ( o7  v ) and @xmath2  sco ( b0  v ), the line profiles are symmetric and narrower.   the presence of time - variable emission and very high - temperature lines in @xmath1  ori  c and @xmath2  sco suggest that magnetically confined wind shocks may be at work.   the grating spectrum of the classical t - tauri star tw  hya is remarkable because the forbidden - line emission of he - like ne  ix and o  vii is very weak, implying that the x - ray emitting region is very dense, @xmath3, or that the x - rays are produced very close to the ultraviolet hotspot at the base of an accretion funnel.   acis light curves and spectra of flares and low - mass and high - mass young stellar objects in orion and @xmath4  ophiuchus further suggest that extreme magnetic activity is a general property of many very young stars.   # 1=.6 # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present high spatial resolution near   infrared @xmath0-band ( 1.65 @xmath1 m ) images, taken with isaac on ut1 of eso vlt, of three radio - loud quasars at z@xmath21.5, as a pilot study for imaging of a larger sample of radio - loud and radio - quiet quasars in the redshift range 1 @xmath3 z @xmath3 2.   we are able to clearly detect the host galaxy in two quasars ( pks 0000 - 177 and pks 0348 - 120 ) and marginally in the third ( pks 0402 - 362 ).   the host galaxies appear compact ( average bulge scale - length r(e ) @xmath2 4 kpc ) and luminous ( average m(h ) = 27.6@xmath40.1 ).   they are @xmath22.5 mag more luminous than the typical galaxy luminosity ( m*(h ) = 25.0@xmath40.2 ), and are comparable to the hosts of low redshift radio - loud quasars ( m(h ) @xmath226 ), taking into account passive stellar evolution.   their luminosities are also similar to those of high redshift radio galaxies.   all three quasars have at least one close companion galaxy at a projected distance @xmath3 50 kpc from the quasar, assuming they are at the same redshift.
we study flare processes in the lower solar atmosphere using observational data for a m1-class flare of june 12, 2014, obtained by new solar telescope ( nst / bbso ) and helioseismic magnetic imager ( hmi / sdo ).   the main goal is to understand triggers and manifestations of the flare energy release in the lower layers of the solar atmosphere ( the photosphere and chromosphere ) using high - resolution optical observations and magnetic field measurements.   we analyze optical images, hmi dopplergrams and vector magnetograms, and use non - linear force - free field ( nlfff ) extrapolations for reconstruction of the magnetic topology.   the nlfff modelling reveals interaction of oppositely directed magnetic flux - tubes in the pil.   these two interacting magnetic flux tubes are observed as a compact sheared arcade along the pil in the high - resolution broad - band continuum images from nst. in the vicinity of the pil, the nst h@xmath0observations reveal formation of a thin three - ribbon structure corresponding to the small - scale photospheric magnetic arcade.   presented observational results evidence in favor of location of the primary energy release site in the dense chromosphere where plasma is partially ionized in the region of strong electric currents concentrated near the polarity inversion line.   magnetic reconnection may be triggered by two interacting magnetic flux tubes with forming current sheet elongated along the pil.
extended @xmath0 theories of gravity have been investigated from the symmetry point of view.   we briefly has been investigated noether symmetry of two types of extended @xmath0 theories : @xmath1 theory, in which curvature is coupled non minimally to the trace of energy momentum tensor @xmath2 and mimetic @xmath3 gravity, a theory with a scalar field degree of freedom, but ghost - free and with internal conformal symmetry. in both cases we write point -like lagrangian for flat friedmann - lemaitre - robertson - walker ( flrw ) cosmological background in the presence of ordinary matter.   we have been shown that some classes of models existed with noether symmetry in these viable extensions of @xmath0 gravity. as a motivated idea,   we have been investigating the stability of the solutions and the bouncing and @xmath4cdm models using the noether symmetries.   we have been shown that in mimetic @xmath0 gravity bouncing and @xmath4cdm solutions are possible.   also a class of solutions with future singularities has been investigated.
motivated by observations of the dynamics of _ myxococcus xanthus _, we present a self - interacting random walk model that describes the competition between chemokinesis and chemotaxis.   cells are constrained to move in one dimension, but release a chemical chemoattractant at a steady state.   the bacteria senses the chemical that it produces.   the probability of direction reversals is modeled as a function of both the absolute level of chemoattractant sensed directly under each cell as well as the gradient sensed across the length of the cell.   if the chemical does not degrade or diffuse rapidly, the one dimensional trajectory depends on the entire past history of the trajectory.   we derive the corresponding fokker - planck equations, use an iterative mean field approach that we solve numerically for short times, and perform extensive monte - carlo simulations of the model.   cell positional distributions and the associated moments are computed in this feedback system.   average drift and mean squared displacements are found.   crossover behavior among different diffusion regimes are found.   specialpagefalse oddhead_physical review e _, * 68 *, 021925, 2003 evenheadoddhead
the main aim of this paper is to introduce automated generation of scripted dialogue as a worthwhile topic of investigation.   in particular the fact that scripted dialogue involves two layers of communication, i.e., uni - directional communication between the author and the audience of a scripted dialogue and bi - directional pretended communication between the characters featuring in the dialogue, is argued to raise some interesting issues.   our hope is that the combined study of the two layers will forge links between research in text generation and dialogue processing.   the paper presents a first attempt at creating such links by studying three types of strategies for the automated generation of scripted dialogue.   the strategies are derived from examples of human - authored and naturally occurring dialogue.
defects in crystalline silicon consisting of a silicon self - interstitial atom and one, two, three, or four hydrogen atoms are studied within density - functional theory ( dft ).   we search for low - energy defects by starting from an ensemble of structures in which the atomic positions in the defect region have been randomized.   we then relax each structure to a minimum in the energy.   we find a new defect consisting of a self - interstitial and one hydrogen atom ( denoted by \{@xmath0,h } ) which has a higher symmetry and a lower energy than previously reported structures.   we recover the \{@xmath0,h@xmath1 } defect found in previous studies and confirm that it is the most stable such defect.   our best \{@xmath0,h@xmath2 } defect has a slightly different structure and lower energy than the one previously reported, and our lowest energy \{@xmath0,h@xmath3 } defect is different to those of previous studies.
grb970402  is the fourth gamma - ray  burst detected by _   beppo_sax  simultaneously in the gamma ray burst monitor ( grbm ) and one of the two wide field cameras ( wfcs ).   a rapid pointing of the _   beppo_sax  narrow field instruments ( nfis ) 8 hours after the grb led to the identification of an unknown weak x - ray  source : 1sax j1450.16920.   its position was approximately at the center of the 3 arcmin error circle derived from the wfc image.   both the medium energy ( mecs, 210 kev ) and low energy ( lecs, 0.110 kev ) concentrators detected the source.   a follow - up observation performed 1.5 days later and lasting 54 ks showed that the source had faded almost to, but not below the detectability threshold.   the flux decrease between the two observations was a factor @xmath0.   1sax j1450.16920  was the second x - ray afterglow associated with a grb.   searches promptly started at other wavelengths ( optical, ir, radio ) did not reveal any transient event within the 3 arcmin error circle.   # 1 # 2 # 3 # 4    = 2em = 1 by 0em # 1, _ # 2 _, * # 3 *, # 4.   # 1    = 2em = 1 by 0em # 1.
an artificial neural network ( ann ) is investigated as a tool for estimating rate coefficients for the collisional excitation of molecules.   the performance of such a tool can be evaluated by testing it on a dataset of collisionally - induced transitions for which rate coefficients are already known : the network is trained on a subset of that dataset and tested on the remainder.   results obtained by this method are typically accurate to within a factor @xmath0 ( median value ) for transitions with low excitation rates and @xmath1 for those with medium or high excitation rates, although 4@xmath2 of the ann outputs are discrepant by a factor of 10 more.   the results suggest that anns will be valuable in extrapolating a dataset of collisional rate coefficients to include high - lying transitions that have not yet been calculated. for the asymmetric top molecules considered in this paper,   the favored architecture is a cascade - correlation network that creates 16 hidden neurons during the course of training, with 3 input neurons to characterize the nature of the transition and one output neuron to provide the logarithm of the rate coefficient.
in the literature, two quite different phase - field formulations for the problem of alloy solidification can be found. in the first  , the material in the diffuse interfaces is assumed to be in an intermediate state between solid and liquid, with a unique local composition. in the second,   the interface is seen as a mixture of two phases that each retain their macroscopic properties, and a separate concentration field for each phase is introduced.   it is shown here that both types of models can be obtained by the standard variational procedure if a grand - potential functional is used as a starting point instead of a free - energy functional.   the dynamical variable is then the chemical potential instead of the composition. in this framework,   a complete analogy with phase - field models for the solidification of a pure substance can be established.   this analogy is then exploited to formulate quantitative phase - field models for alloys with arbitrary phase diagrams.   the precision of the method is illustrated by numerical simulations with varying interface thickness.
we report the discovery of xmmxcs  j2215.9 - 1738, a massive galaxy cluster at @xmath0, which was found in the _ xmm cluster survey_. the cluster candidate was initially identified as an extended x - ray source in archival xmm data.   optical spectroscopy shows that 6 galaxies within a @xmath160 arcsec diameter region lie at @xmath2.   model fits to the x - ray spectra of the extended emission yield @xmath3 kev ( 90% confidence ) ; if there is an undetected central x - ray point source then @xmath4 kev.   the bolometric x - ray luminosity is @xmath5 ergs s@xmath6 over a 2 mpc radial region.   the measured @xmath7, which is the highest known for a cluster at @xmath8, suggests that this cluster is relatively massive for such a high redshift.   the redshift of xmmxcs  j2215.9 - 1738 is the highest currently known for a spectroscopically - confirmed cluster of galaxies.
we consider the analytically solvable model of a gaussian pulse tunneling through a transmission resonance with a general fano characteristic.   it is demonstrated that the transmitted pulse contains enough information to determine uniquely all parameters defining the fano resonance.   this is in contrast to the measurement of the static conductance.   our analytical model is in agreement with numerical data published recently for the limit of a breit - wigner resonance. we identify two opposite pulse propagation regimes : if the resonance is broad compared to the energetic width of the incident gaussian pulse a weakly deformed and slightly delayed transmitted gaussian pulse is found. in the opposite limit of a narrow resonance   the dying out of the transmitted pulse is dominated by the slow exponential decay characteristic of a quasi - bound state with a long life time. in this regime   we find characteristic interference oscillations.
with the sdo / aia instrument, continuous and intermittent plasma outflows are observed on the boundaries of an active region along two distinct open coronal loops. by investigating the temporal sequence magnetograms obtained from hmi / sdo, it is found that small - scale magnetic reconnection probably plays an important role in the generation of the plasma outflows in the coronal loops.   it is found that the origin of the plasma outflows coincides with the locations of the small - scale magnetic fields with mixed polarities, which suggests that the plasma outflows along coronal loops probably results from the magnetic reconnection between the small - scale close emerging loops and the large - scale open active region coronal loops.
we develop a maximum relative entropy formalism to generate optimal approximations to probability distributions.   the central results consist in ( a ) justifying the use of relative entropy as the uniquely natural criterion to select a preferred approximation from within a family of trial parameterized distributions, and ( b ) to obtain the optimal approximation by marginalizing over parameters using the method of maximum entropy and information geometry. as an illustration   we apply our method to simple fluids.   the `` exact '' canonical distribution is approximated by that of a fluid of hard spheres.   the proposed method first determines the preferred value of the hard - sphere diameter, and then obtains an optimal hard - sphere approximation by a suitably weighed average over different hard - sphere diameters.   this leads to a considerable improvement in accounting for the soft - core nature of the interatomic potential. as a numerical demonstration, the radial distribution function and the equation of state for a lennard - jones fluid ( argon )   are compared with results from molecular dynamics simulations.   _ keyword _ : approximation method, maximum entropy, marginalization, simple fluids, hard sphere approximation + _ pacs _ : 05.20.gg, 05.20.jj
we consider the transition from quark to hadronic matter which may result during the cooling / expansion of the quark - gluon plasma formed in energetic collisions of weakly asymmetric ions.   this transition involves the energy density of @xmath0 and @xmath1 quark matter and the one of nearly isospin - symmetric nuclear matter. within bag models,   the former entails knowledge of the bag pressure, a poorly constrained quantity.   the bag pressure at high - density can be fixed imposing equality of quark and nucleonic energy densities at the ( assumed known ) transition point.   we find this value to be very model dependent.
a search for young massive star clusters ( ymcs ) in the nearby face - on spiral galaxy m51 ( ngc  5194 ) has been carried out using @xmath0 ccd images from the prime focus camera on the lick 3 meter shane telescope. the ymc population is found to be quite rich with a specific @xmath1-band luminosity @xmath2, consistent with the high current star formation rate of this galaxy.   the brightest clusters have @xmath3, far brighter than any young clusters currently known in the milky way and even surpassing the luminosity of the r136 cluster in the 30 dor complex in the large magellanic cloud.   a few of the ymcs are examined on archive hst / wfpc2 images, confirming their cluster nature and providing estimates of their effective radii of @xmath4 pc.   the number of ymcs in m51 is compatible with extrapolation of a power - law luminosity function with exponent @xmath5 from a milky way - like population of open clusters.   both the sfr and  of m51 are similar to those of other cluster - rich spiral galaxies like ngc  1313 and m83.   epsf    galaxies : spiral  galaxies : star clusters  galaxies : individual ( ngc  5194 )  galaxies : interactions
the usual formulation of quantum theory is rather abstract. in recent work   i have shown that we can, nevertheless, obtain quantum theory from five reasonable axioms.   four of these axioms are obviously consistent with both classical probability theory and quantum theory.   the remaining axiom requires that there exists a continuous reversible transformation between any two pure states.   the requirement of continuity rules out classical probability theory. in this paper   i will summarize the main points of this new approach.   i will leave out the details of the proof that these axioms are equivalent to the usual formulation of quantum theory ( for these see reference @xcite ).
we compute that extrasolar minor planets can retain much of their internal h@xmath0o during their host star s red giant evolution.   the eventual accretion of a water - rich body or bodies onto a helium white dwarf might supply an observable amount of atmospheric hydrogen, as seems likely for gd 362.   more generally, if hydrogen pollution in helium white dwarfs typically results from accretion of large parent bodies rather than interstellar gas as previously supposed, then h@xmath0o probably constitutes at least 10% of the aggregate mass of extrasolar minor planets.   one observational test of this possibility is to examine the atmospheres of externally - polluted white dwarfs for oxygen in excess of that likely contributed by oxides such as sio@xmath0.   the relatively high oxygen abundance previously reported in gd 378 plausibly but not uniquely can be explained by accretion of an h@xmath0o - rich parent body or bodies.   future ultraviolet observations of white dwarf pollutions can serve to investigate the hypothesis that environments with liquid water that are suitable habitats for extremophiles are widespread in the milky way.
we have developed a rigorous quantum model of spontaneous parametric down - conversion in a nonlinear 1d photonic - band - gap structure based upon expansion of the field into monochromatic plane waves.   the model provides a two - photon amplitude of a created photon pair.   the spectra of the signal and idler fields, their intensity profiles in the time domain, as well as the coincidence - count interference pattern in a hong - ou - mandel interferometer are determined both for cw and pulsed pumping regimes in terms of the two - photon amplitude.   a broad range of parameters characterizing the emitted down - converted fields can be used. as an example  , a structure composed of 49 layers of gan / aln is analyzed as a suitable source of photon pairs having high efficiency.
we propose that viewing angle expansion of the holographic image can be realized by using high - order diffraction beams caused by the pixel structure sampling the hologram data.   the diffractive beam propagating to new optical axis direction plays a role in a modulated carrier similar to a carrier signal of the off - axis holography, which makes new viewing zone of the reconstruction image.   the reconstructed image in the fresnel hologram is deformed along new viewing direction, whereas the fourier hologram enables to retrieve three - dimensional image with other perspective.   high - resolution hologram fringe is imaged on the image plane through an imaging system, and thus, only collection of diffracted beams increases a viewing zone angle.   we verify our proposal through the numerical analysis for the sampled hologram showing high - order diffraction beams with various viewing zones.   ocis codes : ( 090.2870 ) holographic display ; ( 090.1995 ) digital holography ; ( 090.1970 ) diffractive optics
density - functional theory has been applied to investigate systematics of sodium clusters na@xmath0 in the size range of @xmath1= 39 - 55.   a clear evolutionary trend in the growth of their ground - state geometries emerges.   the clusters at the beginning of the series ( @xmath1=39 - 43 ) are symmetric and have partial icosahedral ( two - shell ) structure.   the growth then goes through a series of disordered clusters ( @xmath1=44 - 52 ) where the icosahedral core is lost.   however, for @xmath253 a three shell icosahedral structure emerges.   this change in the nature of the geometry is abrupt.   in addition, density - functional molecular dynamics has been used to calculate the specific heat curves for the representative sizes @xmath1= 43, 45, 48 and 52.   these results along with already available thermodynamic calculations for @xmath1= 40, 50, and 55 enable us to carry out a detailed comparison of the heat capacity curves with their respective geometries for the entire series.   our results clearly bring out strong correlation between the evolution of the geometries and the nature of the shape of the heat capacities.   the results also firmly establish the size - sensitive nature of the heat capacities in sodium clusters.
a one - way coupled spatiotemporally chaotic map lattice is used to contruct cryptosystem. with the combinatorial applications of both chaotic computations and conventional algebraic operations  , our system has optimal cryptographic properties much better than the separative applications of known chaotic and conventional methods.   we have realized experiments to pratice duplex voice secure communications in realistic wired public switched telephone network by applying our chaotic system and the system of advanced encryption standard ( aes ), respectively, for cryptography.   our system can work stably against strong channel noise when aes fails to work.   keywords : spatiotemporal chaos ; chaotic cryptography ; error function attack
using the full - potential local orbital minimum - basis method, the ti@xmath0-based full - heusler alloys are studied.   the results show that these compounds exhibit a half - metallic behavior, however, in contrast to the conventional full - heusler alloys, the full - heusler alloys show a slater - pauling behavior and the total spin magnetic moment per unit cell ( @xmath1 ) following the rule @xmath1=@xmath2 - 18.   the origin of the gap in these half - metallic alloys are well understood.   it is found that the half - metallic properties of ti@xmath0-based compounds are insensitive to the lattice distortion and a fully spin polarization can be obtained within a wide range of lattice parameters.   this is favorable in practical application.   a. magnetic intermetallics ; e. @xmath3-@xmath4 calculations ; g. magnetic applications ;
entanglement between degrees of freedom, namely between the spin, path and ( total ) energy degrees of freedom, for single neutrons is exploited.   we implemented a triply entangled greenberger - horne - zeilinger(ghz)-like state and coherently manipulated relative phases of two - level quantum subsystems.   an inequality derived by mermin was applied to analyze the generated ghz - like state : we determined the four expectation values and finally obtained @xmath0.   this demonstrates the violation of a mermin - like inequality for triply entangled ghz - like state in a single - particle system, which, in turn, exhibits a clear inconsistency between noncontextual assumptions and quantum mechanics and confirms quantum contextuality.   neutron interferometer, entanglement, ghz - state, contextuality, degrees of freedom, spin, path, energy
we show the existence of two families of short grbs, both originating from the merger of binary neutron stars ( nss ) : with @xmath0 erg, leading to a massive ns as the merged core, and with @xmath1 erg, leading to a black hole ( bh ). following the identification of the prototype grb 090227b, we present the details of a new example of short burst : grb 140619b. from the spectral analysis of the early @xmath2 s, we infer an observed temperature @xmath3 kev of the @xmath4-plasma at transparency ( p - grb ), a theoretically derived redshift @xmath5, a total burst energy @xmath6 erg, a rest - frame peak energy @xmath7 mev, and a baryon load @xmath8.   we also estimate the corresponding emission of gravitational waves.   two additional examples of short bursts are identified : grb 081024b and grb 090510, remarkable for its well determined cosmological distance.   we show that marked differences exist in the nature of the afterglows of these two families of short bursts : bursts, leading to bh formation, consistently exhibit high energy emission following the p - grb emission ; bursts, leading to the formation of a massive ns, should never exhibit high energy emission.   we also show that both the families fulfill an @xmath9@xmath10 relation with slope @xmath11 and a normalization constant incompatible with the one for long grbs  . the observed rate of such events is @xmath12gpc@xmath13yr@xmath14.
the orientation of a massive binary undergoes a random walk due to gravitational encounters with field stars.   the rotational diffusion coefficient for a circular - orbit binary is derived via scattering experiments.   the binary is shown to reorient itself by an angle of order @xmath0 during the time that its semi - major axis shrinks appreciably, where @xmath1 is the binary mass and @xmath2 the perturber mass.   implications for the orientations of rotating black holes are discussed.
we derive within a time - dependent scattering formalism expressions for both the current through ac - driven nanoscale conductors and its fluctuations.   the results for the time - dependent current, its time average, and, above all, the driven shot noise properties assume an explicit and serviceable form by relating the propagator to a non - hermitian floquet theory.   the driven noise can not be expressed in terms of transmission probabilities.   the results are valid for a driving of arbitrary strength and frequency.   the connection with commonly known approximation schemes such as the tien - gordon approach or a high - frequency approximation is elucidated together with a discussion of the corresponding validity regimes. within this formalism  , we study the coherent suppression of current and noise caused by properly chosen electromagnetic fields.
we model the multi - wavelength emission in the southern hotspot of the radio quasar 4c74.26.   the synchrotron radio emission is resolved near the shock with the merlin radio - interferometer, and the rapid decay of this emission behind the shock is interpreted as the decay of the amplified downstream magnetic field as expected for small scale turbulence.   electrons are accelerated to only @xmath0  tev, consistent with a diffusion coefficient many orders of magnitude greater than in the bohm regime.   if the same diffusion coefficient applies to the protons, their maximum energy is only @xmath1  tev.
imaging atmosphere cherenkov telescopes ( iact ) are arrays of very large optical telescopes that are well - suited for rapid photometry of bright sources.   i investigate their potential in observing stellar occultations by small objects in the outer solar system, transjovian objects ( tjos ).   these occultations cast diffraction patterns on the earth.   current iact arrays are capable of detecting objects smaller than 100 metres in radius in the kuiper belt and 1 km radius out to 5000 au.   the future cherenkov telescope array ( cta ) will have even greater capabilities. because the arrays include several telescopes, they can potentially measure the speeds of tjos without degeneracies, and the sizes of the tjos and background stars.   i estimate the achievable precision using a fisher matrix analysis. with cta  , the precisions of these parameter estimations will be as good as a few percent.   i consider how often detectable occultations occur by members of different tjo populations, including centaurs, kuiper belt objects ( kbos ), oort cloud objects, and satellites and trojans of uranus and neptune.   the great sensitivity of iact arrays means that they likely detect kbo occultations once every @xmath0 hours when looking near the ecliptic.   iacts can also set useful limits on many other tjo populations.   kuiper belt : general  oort cloud  minor planets, asteroids, general  occultations
in this work, the effects of magnetic field on a holographic superconductor have been studied in non - commutative background through the ads - cft correspondence.   the non - commutative correction has been incorporated here is the generalization of the schwarzschild black hole metric in ads.   it has been found that the non - commutative effects tend to work against the black hole hair formation.   this in turn shows negative effect on holographic superconductors.   indeed, it reduces the value of the critical magnetic field and furthermore the critical magnetic field vanishes before the temperature reaches to its critical value.   + keywords : ads - cft correspondence, non - commutative geometry, holographic superconductor.
motivated by recent experiments reporting non - gaussian velocity distributions in driven dilute granular materials, we study by numerical simulation the properties of inelastic gases as functions of the coefficient of restitution @xmath0 and concentration @xmath1 with various heating mechanisms. we show that there are marked, qualitative differences in the behavior for uniform heating ( as is frequently assumed theoretically ) and for particle systems driven at the boundaries of the container ( as is frequently done in experiments ).   in general, we find gaussian velocity distributions for uniform heating and non - gaussian velocity distributions for boundary heating.   furthermore, we demonstrate that the form of the observed velocity distribution is governed primarily by the coefficient of restitution @xmath0 and @xmath2, the ratio between the average number of heatings and the average number of collisions in the gas.   the differences in distributions we find between uniform and boundary heating can then be understood as different limits of @xmath3, for @xmath4 and @xmath5 respectively.   moreover, we demonstrate that very similar behavior is found for a simple model of a gas of inelastic particles with no spatial degrees of freedom.
we investigate theoretically the dissociative ionization of a @xmath0  molecule using two ultrashort laser ( pump - probe ) pulses.   the pump pulse prepares a dissociating nuclear wave packet on an ungerade surface of @xmath0 .   next, an uv ( or xuv ) probe pulse ionizes this dissociating state at large ( r = 20 - 100 bohr ) internuclear distance.   we calculate the momenta distributions of protons and photoelectrons which show a ( two - slit - like ) interference structure.   a general, simple interference formula is obtained which depends on the electron and protons momenta, as well as on the pump - probe delay on the pulses durations and polarizations. this interference can be interpreted as visualization of an electron state delocalized over the two - centres.   this state is an entangled state of a hydrogen atom with a momentum @xmath1 and a proton with an opposite momentum @xmath2 dissociating on the ungerade surface of @xmath0 .   this pump - probe scheme can be used to reveal the nonlocality of the electron which intuitively should be localized on just one of the protons separated by the distance r much larger than the atomic bohr orbit.
the asymmetric shape of the nebula around @xmath0-carinae ( homunculus ) can be explained by a spherical expansion in a non - homogeneous medium.   two models are analyzed : an exponential and an inverse power law dependence for the density as a function of distance from the equatorial plane.   the presence of a medium with variable density along the polar direction progressively converts the original spherical shell into a bipolar nebula. in the case of the nebula around @xmath0-carinae, we know the time elapsed since the great outburst in 1840. an exact match between observed radii and velocities can be obtained by fine tuning the parameters involved, such as initial radius, initial velocity and the typical scale that characterizes the gradient in density.   the observed radius and velocity of the homunculus as a function of the polar angle in spherical coordinates can be compared with the corresponding simulated data by introducing the efficiency in a single or multiple directions.   once the 3d spatial structure of the homunculus is obtained, we can compose the image by integrating along the line of sight. in order to simulate the observed image,   we have considered a bipolar nebula with constant thickness and an optically thin emitting layer.   some simulated cuts of the relative intensity are reported and may represent a useful reference for the astronomical cuts.   ism : molecules, stars : individual : eta- carinae, stars : mass loss, stars : winds, outflows    = 0.5 cm
consider a multi - input multi - output ( mimo ) downlink multi - user channel.   a well - studied problem in such system is the design of linear beamformers for power minimization with the quality of service ( qos ) constraints.   the most representative algorithms for solving this class of problems are the so - called mmse - socp algorithm @xcite and the udd algorithm @xcite.   the former is based on alternating optimization of the transmit and receive beamformers ; while the latter is based on the well - known uplink - dowlink duality theory. despite their wide applicability  , the convergence ( to kkt solutions ) of both algorithms is still open in the literature. in this paper  , we rigorously establish the convergence of these algorithms for qos - constrained power minimization ( qcpm ) problem with both single stream and multiple streams per user cases.   key to our analysis is the development and analysis of a new mmse - dual algorithm, which connects the mmse - socp and the udd algorithm.   our numerical experiments show that 1 ) all these algorithms can almost always reach points with the same objective value irrespective of initialization ; 2 ) the mmse - socp / mmse - dual algorithm works well while the udd algorithm may fail with an infeasible initialization.
we show how to evaluate one - dimensional minkowski - region mellin   barnes representations arising from massive loop integrals, by modifying the contours of integration.   we implement an exact solution to the differential equation determining the contours of stationary phase.   we also present several simple approximations to these contours.   our approach points the way to more efficient computations of massless and massive mellin   barnes integrals in both euclidean and minkowski regions.
recent observational results obtained with scuba, cobe and iso have greatly improved our knowledge of the infrared and sub - mm background radiation.   these limits become constraining given the realization that most agns are heavily obscured and must reradiate strongly in the ir / sub - mm.   here we predict the contribution of agns to the ir / sub - mm background, starting from measurements of the hard x - ray background.   we show that an application of what we know of agn spectral energy distributions ( seds ) and the ir background requires that a significant fraction of the 10 - 150  @xmath0 m background comes from agns.   this conclusion can only be avoided if obscured agns are intrinsically brighter in the x - rays ( with respect to the optical - uv ) than unobscured agns, contrary to `` unified schemes '' for agns, or have a dust to gas ratio much lower ( @xmath1 ) than galactic.   we show that these results are rather robust and not strongly dependent on the details of the modeling.
in this paper we present an algorithm to compute risk averse policies in markov decision processes ( mdp ) when the total cost criterion is used together with the average value at risk ( avar ) metric.   risk averse policies are needed when large deviations from the expected behavior may have detrimental effects, and conventional mdp algorithms usually ignore this aspect.   we provide conditions for the structure of the underlying mdp ensuring that approximations for the exact problem can be derived and solved efficiently.   our findings are novel inasmuch as average value at risk has not previously been considered in association with the total cost criterion.   our method is demonstrated in a rapid deployment scenario, whereby a robot is tasked with the objective of reaching a target location within a temporal deadline where increased speed is associated with increased probability of failure.   we demonstrate that the proposed algorithm not only produces a risk averse policy reducing the probability of exceeding the expected temporal deadline, but also provides the statistical distribution of costs, thus offering a valuable analysis tool.
we compare predictions of the mean - field theory of superconductivity for nearly - antiferromagnetic and nearly - ferromagnetic metals for cubic and tetragonal lattices.   the calculations are based on the parameterisation of an effective interaction arising from the exchange of the magnetic fluctuations and assume that a single band is relevant for superconductivity.   the results show that for comparable model parameters, the robustness of magnetic pairing increases gradually as one goes from a cubic structure to a more and more anisotropic tetragonal structure either on the border of antiferromagnetism or ferromagnetism.
we analyse the potential migration of massive planets forming far away from an inner planetary system. for this  , we follow the dynamical evolution of the orbital elements of a massive planet undergoing a dissipative process with a gas disc centred around the central sun.   we use a new method for post - newtonian, high - precision integration of planetary systems containing a central sun by splitting the forces on a particle between a dominant central force and additional perturbations. in this treatment, which allows us to integrate with a very high - accuracy close encounters,   all gravitational forces are integrated directly, without resorting to any simplifying approach. after traversing the disc a number of times, the planet   is finally trapped into the disc with a non - negligible eccentricity
the conditional entropy of glueball states is calculated using a holographic description.   glueball states are represented by a supergravity dual picture, consisting of a 5-dimensional graviton - dilaton action of a dynamical holographic ads / qcd model.   the conditional entropy is studied as a function of the glueball spin and of the mass, providing information about the stability of the glueball states.
we construct gravitational dynamics for finsler spacetimes in terms of an action integral on the unit tangent bundle.   these spacetimes are generalizations of lorentzian metric manifolds which satisfy necessary causality properties.   a coupling procedure for matter fields to finsler gravity completes our new theory that consistently becomes equivalent to einstein gravity in the limit of metric geometry.   we provide a precise geometric definition of observers and their measurements, and show that the transformations by means of which different observers communicate form a groupoid that generalizes the usual lorentz group.   moreover, we discuss the implementation of finsler spacetime symmetries.   we use our results to analyze a particular spacetime model that leads to finsler geometric refinements of the linearized schwarzschild solution.
in this contribution we focus on results from chemical evolution models for the solar neighbourhood obtained by varying the imf.   results for galaxies of different morphological type are discussed as well.   they argue against a universal imf independent of star forming conditions.
a study of hadron pair production mechanism is motivated by the recent observed decays @xmath0.   one novel phenomenon is threshold enhancement of the kaon pair production.   we show that these decays in the heavy quark mass limit can be factorized into a generalized form.   the new non - perturbative quantity is the generalized distribution amplitude which describes how a quark - antiquark pair transmits into the hadron pair.   a proof of factorization of @xmath0 decays to all - orders is performed by using the soft - collinear effective theory.   the phenomenological application is discussed in brief.
we present a search for spatial and redshift correlations in a 2   resolution spectroscopic survey of the  forest at @xmath0 toward ten qsos concentrated within a 1@xmath1 diameter field.   we find a signal at @xmath2 significance for correlations of the  absorption line wavelengths between different lines of sight over the whole redshift range.   the significance rises to @xmath3 if we restrict the redshift range to @xmath4, and to @xmath5 if we further restrict the sample to lines with rest equivalent width @xmath6.   we conclude that a significant fraction of the  forest arises in structures whose correlation length extends at least over 30 arcmin ( @xmath7 comoving mpc at @xmath8 for @xmath9  mpc@xmath10, @xmath11, @xmath12 ).   we have also calculated the three dimensional two point correlation function for  absorbers ; we do not detect any significant signal in the data.   however, we note that line blending prevents us from detecting the signal produced by a 100% overdensity of absorbers in simulated data.   we find that the  forest redshift distribution provides a more sensitive test for such clustering than the three dimensional two point correlation function.   @scaling.95 # 1@scaling#1    # 1 = @scaling    # 1#2=.45 =.45    # 1#2#3#4#5#6#7    to#2   ''' ''    # 1to 0pt#1   . ^m.   ^s.  .  .
we examine the problem of jet reconstruction at heavy - ion colliders using jet - area - based background subtraction tools as provided by fastjet.   we use monte carlo simulations with and without quenching to study the performance of several jet algorithms, including the option of filtering, under conditions corresponding to rhic and lhc collisions.   we find that most standard algorithms perform well, though the anti-@xmath0 and filtered cambridge / aachen algorithms have clear advantages in terms of the reconstructed @xmath1 offset and dispersion.   cern - ph - th/2010 - 223 + october 2010 +
the non - gaussian cold spot found in the wmap data has created controversy about its origin.   here we calculate the bayesian posterior probability ratios for three different models that could explain the cold spot.   a recent work claimed that the spot could be caused by a cosmic texture, while other papers suggest that it could be due to the gravitational effect produced by an anomalously large void.   also the sunyaev - zeldovich effect caused by a cluster is taken into account as a possible origin.   we perform a template fitting on a @xmath0 radius patch centered at galactic coordinates ( @xmath1 ) and calculate the posterior probability ratios for the void and sunyaev - zeldovich models, comparing the results to those obtained with texture. taking realistic priors for the parameters,   the texture interpretation is favored, while the void and sunyaev - zeldovich hypotheses are discarded.   the temperature decrement produced by voids or clusters is negligible considering realistic values for the parameters.   = = = = = = = =    # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn @mathgroup@bold@groupeurbn @mathgroup@group @mathgroup@normal@groupmsamn @mathgroup@bold@groupmsamn =  019 =  016 =  040 =  336 =  33e = = = = = = = =    # 1 # 1 # 1 # 1 = = = = = = = =    methods : data analysis - cosmic microwave background
specific heat measurements have been successfully used to probe unconventional superconducting phases in one - band heavy - fermion and organic superconductors.   we extend the method to study successive phase transitions in multi - band materials such as iron based superconductors.   the signatures are multiple peaks in the specific heat, at low temperatures and high magnetic field, which can lead the experimental verification of unconventional superconducting states with non - zero total momentum.   february 2014    _ keywords _ : superconductivity, pnictides, fflo, phase transitions +    ( some figures may appear in colour only in the online journal )
motivated by the mit experiment [ gorlitz _ et al. _,   phys. rev  . lett. * 87 *, 130402 ( 2001 ) ], we analytically study the effect of density and phase fluctuations on various observables in a quasi one - dimensional degenerate bose gases. quantizing the gross - pitaevskii hamiltonian and   diagonalize it in terms of the normal modes associated with the density and phase fluctuations of a quasi - one dimensional bose gas.   we calculate dynamic structure factor @xmath0 from low - energy condensate density fluctuations and find that there are multiple peaks in @xmath0 for a given momentum @xmath1 due to the discrete spectrum.   these multiple peaks can be resolved by a two - photon bragg pulse with a long duration which transfer the momentum to the system.   we calculate the momentum transferred @xmath2 by using the phase - density representation of the bose order parameter.   we also calculate the single - particle density matrix, phase coherence length, and momentum distribution by taking care of the phase fluctuations upto fourth - order term as well as the density fluctuations.   our studies on coherence properties shows that 1d bose gases of mit experiment do not form a true condensate, but it can be obtained by a moderate changes of the current experimental parameters.   2 
the impact of hst photometry and european astronomy in studies concerning the star formation histories of resolved galaxies is described.   our current knowledge of the star formation history of systems within 10 - 20 mpc, as derived from the colour - magnitude diagrams of their resolved stellar populations, is reviewed, as well as the impact of these results on our understanding of galaxy evolution.
we study the effect of dielectric inhomogeneities on the interaction between two planparallel charged surfaces with oppositely charged mobile charges in between.   the dielectric constant between the surfaces is assumed to be different from the dielectric constant of the two semiinfinite regions bounded by the surfaces, giving rise to electrostatic image interactions.   we show that on the weak coupling level the image charge effects are generally small, making their mark only in the second order fluctuation term. however, in the strong coupling limit, the image effects are large and fundamental.   they modify the interactions between the two surfaces in an essential way.   our calculations are particularly useful in the regime of parameters where computer simulations would be difficult and extremely time consuming due to the complicated nature of the long range image potentials.
we present a scheme for locking optical cavities with arbitrary detuning many line widths from resonance using an electro - optic modulator that can provide arbitrary ratios of amplitude to phase modulation.   we demonstrate our scheme on a fabry - perot cavity, and show that a well - behaved linear error signal can be obtained by demodulating the reflected light from a cavity that is detuned by several line widths.
radio galaxies are the only non - blazar agn detected in the vhe band.   these objects enable the investigation of the main substructures of the agn, in particular the core, the jet and its interaction with the intergalactic environment.   veritas observations have included exposures on a number of radio galaxies.   recently, the discovery by _ fermi _ of gev emission from the radio galaxy ngc  1275 triggered veritas observations of this source. results from the veritas observations of radio galaxies and future plans are presented.
we study the emergence and dynamics of pointer states in the motion of a quantum test particle affected by collisional decoherence.   these environmentally distinguished states are shown to be exponentially localized solitonic wave functions which evolve according to the classical equations of motion.   we explain their formation using the orthogonal unraveling of the master equation, and we demonstrate that the statistical weights of the arising mixture are given by projections of the initial state onto the pointer basis  .    published in : j.  phys.   a :  math.  theor.   43, 015303 ( 2010 )
we report on both high - precision photometry from the _ most _ space telescope and ground - based spectroscopy of the triple system @xmath0 ori a consisting of a binary o9.5ii+early - b ( aa1 and aa2 ) with @xmath1 5.7d, and a more distant tertiary ( o9 iv @xmath2 yrs ).   this data was collected in concert with x - ray spectroscopy from the chandra x - ray observatory.   thanks to continuous coverage for 3 weeks, the _ most _ light curve reveals clear eclipses between aa1 and aa2 for the first time in non - phased data. from the spectroscopy we have a well constrained radial velocity curve of aa1. while we are unable to recover radial velocity variations of the secondary star, we are able to constrain several fundamental parameters of this system and determine an approximate mass of the primary using apsidal motion.   we also detected second order modulations at 12 separate frequencies with spacings indicative of tidally influenced oscillations.   these spacings have never been seen in a massive binary, making this system one of only a handful of such binaries which show evidence for tidally induced pulsations.
we study spatial self - organisation and dynamical phase - space compression of a dilute cold gas of laser - illuminated polarisable particles in an optical resonator. deriving a non - linear fokker   planck equation for the particles phase - space density allows us to treat arbitrarily large ensembles in the far - detuning limit and explicitly calculate friction forces, momentum diffusion and steady - state temperatures.   in addition, we calculate the self - organisation threshold in a self - consistent analytic form. for a homogeneous ensemble below threshold the cooling rate for fixed laser power is largely independent of the particle number.   cooling leads to a @xmath0-gaussian velocity distribution with a steady - state temperature determined by the cavity linewidth.   numerical simulations using large ensembles of particles confirm the analytical threshold condition for the appearance of an ordered state, where the particles are trapped in a periodic pattern and can be cooled to temperatures close to a single vibrational excitation.
we implement self - consistent microscopic calculations in order to describe out - of - equilibrium non - local transport in normal metal - superconductor - normal metal hybrid structures in the presence of a magnetic field and for arbitrary interface transparencies. a four terminal setup simulating usual experimental situations   is described by means of a tight - binding model.   we present results for the self - consistent order parameter and current profiles within the sample.   these profiles illustrate a crossover from a quasi - equilibrium to a strong non - equilibrium situation when increasing the interface transparencies and the applied voltages.   we analyze in detail the behavior of the non - local conductance in these two different regimes. while in quasi - equilibrium conditions   this can be expressed as the difference between elastic cotunneling and crossed andreev transmission coefficients, in a general situation additional contributions due to the voltage dependence of the self - consistent order parameter have to be taken into account.   the present results provide a first step towards a self - consistent theory of non - local transport including non - equilibrium effects and describe qualitatively a recent experiment [ phys.   rev.   lett. * 97 *, 237003 ( 2006 ) ].
networks are a powerful abstraction with applicability to a variety of scientific fields.   models explaining their morphology and growth processes permit a wide range of phenomena to be more systematically analysed and understood. at the same time, creating such models is often challenging and requires insights that may be counter - intuitive.   yet there currently exists no general method to arrive at better models.   we have developed an approach to automatically detect realistic decentralised network growth models from empirical data, employing a machine learning technique inspired by natural selection and defining a unified formalism to describe such models as computer programs.   as the proposed method is completely general and does not assume any pre - existing models, it can be applied `` out of the box '' to any given network. to validate our approach empirically,   we systematically rediscover pre - defined growth laws underlying several canonical network generation models and credible laws for diverse real - world networks.   we were able to find programs that are simple enough to lead to an actual understanding of the mechanisms proposed, namely for a simple brain and a social network.
graphene research is currently one of the largest fields in condensed matter. due to its unusual electronic spectrum with dirac - like quasiparticles, and   the fact that it is a unique example of a metallic membrane, graphene has properties that have no match in standard solid state textbooks. in these lecture notes,   i discuss some of these properties that are not covered in detail in recent reviews @xcite.   we study the particular aspects of the physics / chemistry of carbon that influence the properties of graphene ; the basic features of graphene s band structure including the @xmath0 and @xmath1 bands ; the phonon spectra in free floating graphene ; the effects of a substrate on the structural properties of graphene ; and the effect of deformations in the propagation of electrons.   the objective of these notes is not to provide an unabridged theoretical description of graphene but to point out some of the peculiar aspects of this material.   = 10000
entanglement speeds up evolution of a pure bipartite spin state, in line with the time energy uncertainty.   however if the state is mixed this is not necessarily the case.   we provide a counter example and point to other factors affecting evolution in mixed states, including classical correlations and entropy.
recently there has been great interest around quantum relativistic models for plasmas. in particular striking advances   have been obtained by means of the klein - gordon - maxwell system, which provides a first order approach to the relativistic regimes of quantum plasmas.   it is a reliable method as long as the plasma spin dynamics is not a fundamental aspect, to be addressed using more refined ( and heavier ) models involving the pauli - schrdinger or dirac equations. in this work a further simplification   is considered, tracing back to the early days of relativistic quantum theory.   namely, we revisit the square - root klein - gordon - poisson system, where the positive branch of the relativistic energy - momentum relation is mapped to a quantum wave equation. the associated linear wave propagation is analyzed and compared to the results in the literature.   we determine physical parameters where the simultaneous quantum and relativistic effects can be noticeable in weakly coupled electrostatic plasmas.
recent measurements of type ia supernovae indicate that distant supernovae are substantially fainter than expected from the standard flat cold dark matter model.   one possible explanation is that the energy density in our universe is in fact dominated by a cosmological constant.   another possible solution is that there are large amounts of grey dust in the intergalactic medium.   dust grains can be grey either because they are non - spherical or very large.   we have numerically investigated whether grey dust can be emitted from high redshift galaxies without also emitting standard, reddening dust, which would have been visible in the spectra of high redshift objects.   our finding is that grain velocities are almost independent of ellipticity so that if greyness are due to the grains being elongated, it will not be possible to separate grey dust from ordinary dust.   we also find that velocities are fairly independent of grain size, but we can not rule out possible sputtering of small grains, so that large, grey dust grains could be preferentially emitted. therefore, our conclusion is that grey dust is an unlikely explanation of the data, but we can not rule it out if the grey dust consists of large, spherical grains.
a type  ia supernova explosion likely begins as a nuclear runaway near the center of a carbon - oxygen white dwarf.   the outward propagating flame is unstable to the landau - darrieus, rayleigh - taylor, and kelvin - helmholtz instabilities, which serve to accelerate it to a large fraction of the speed of sound.   we investigate the rayleigh - taylor unstable flame at the transition from the flamelet regime to the distributed - burning regime, around densities of @xmath0, through detailed, fully resolved simulations. a low mach number, adaptive mesh hydrodynamics code is used to achieve the necessary resolution and long time scales. as the density   is varied, we see a fundamental change in the character of the burning  at the low end of the density range the rayleigh - taylor instability dominates the burning, whereas at the high end the burning suppresses the instability. in all cases, significant acceleration of the flame is observed, limited only by the size of the domain we are able to study.   we discuss the implications of these results on the potential for a deflagration to detonation transition.
we examine collisions of moving solitons in a fiber bragg grating with a _ triplet _ composed of two closely set repulsive defects of the grating and an attractive one inserted between them.   a _ doublet _ ( dipole ), consisting of attractive and repulsive defects with a small distance between them, is considered too.   systematic simulations demonstrate that the triplet provides for superior results, as concerns the capture of a free pulse and creation of a _ standing optical soliton _, in comparison with recently studied traps formed by single and paired defects, as well as the doublet : 2/3 of the energy of the incident soliton can be captured when its velocity attains half the light speed in the fiber ( the case most relevant to the experiment ), and the captured soliton quickly relaxes to a stationary state. a subsequent collision between another free soliton and   the pinned one is examined too, demonstrating that the impinging soliton always bounces back, while the pinned one either remains in the same state, or is kicked out forward, depending on the collision velocity and phase shift between the solitons.
we introduce phase operators associated with the algebra su(3 ), which is the appropriate tool to describe three - level systems.   the rather unusual properties of this phase are caused by the small dimension of the system and are explored in detail.   when a three - level atom interacts with a quantum field in a cavity, a polynomial deformation of this algebra emerges in a natural way.   we also introduce a polar decomposition of the atom - field relative amplitudes that leads to a hermitian relative - phase operator, whose eigenstates correctly describe the corresponding phase properties.   we claim that this is the natural variable to deal with quantum interference effects in atom - field interactions.   we find the probability distribution for this variable and study its time evolution in some special cases.
a unified framework for analyzing generalized synchronization in coupled chaotic systems from data is proposed.   the key of the proposed approach is the use of the _ kernel methods _ recently developed in the field of machine learning.   several successful applications are presented, which show the capability of the kernel - based approach for detecting generalized synchronization, and dynamical change of the coupling strength between two chaotic systems can be captured by the proposed approach.   it is also discussed how the kernel parameter is suitably chosen from data.
morphologically it appears as if the pwn consists of two emission regions : whereas x - ray ( @xmath0 kev ) and very high energy ( vhe ) _   h.e.s.s.   _ @xmath1-ray observations appear to define a cocoon type shape south of the pulsar, radio observations reveal an extended area of size @xmath2 ( including the cocoon area ), also south of the vela pulsar. since no wide field of view ( fov ) observations of the synchrotron emission between radio and x - rays are available, we do not know how the lepton ( @xmath3 ) spectra of these two components connect and how the morphology changes with energy.   currently we find that two distinct lepton spectra describe the respective radio and x - ray / vhe @xmath1-ray spectra, with a field strength of @xmath4 g self - consistently describing a radiation spectral break ( or energy maximum ) in the multi - tev domain as observed by _ h.e.s.s. _   ( if interpreted as ic radiation ), while predicting the total hard x - ray flux above 20 kev ( measured by the wide fov _ integral _   instrument ) within a factor of two.   if this same field strength is also representative of the radio structure ( including filaments ), the implied ic component corresponding to the highest radio frequencies should reveal a relatively bright high energy @xmath1-ray structure and _ fermi lat _ should be able to resolve it.   a higher field strength in the filaments would however imply fewer leptons in and hence a fainter _ fermi lat _ signal.
the clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory.   we use the results from time - dependent hydrodynamical models of the instability in the line - driven wind of a massive supergiant star to derive the time - dependent accretion rate on to a compact object in the bondi - hoyle - lyttleton approximation. the strong density and velocity fluctuations in the wind result in strong variability of the synthetic x - ray light curves.   photoionization of inhomogeneous winds is different from the photoinization of smooth winds.   the degree of ionization is affected by the wind clumping.   the wind clumping must also be taken into account when comparing the observed and model spectra of the photoionized stellar wind.
we study cooling of the collective vibrational motion of two @xmath0ba@xmath1 ions confined in an electrodynamic trap and irradiated by laser light close to the resonances s@xmath2-p@xmath2 ( 493 nm ) and p@xmath2-d@xmath3 ( 650 nm ).   the motional state of the ions is monitored by a spatially resolving photomultiplier.   depending on detuning and intensity of the cooling lasers, macroscopically different motional states corresponding to different ion temperatures are observed.   we also derive the ions temperature from detailed analytical calculations of laser cooling taking into account the zeeman structure of the energy levels involved.   the observed motional states perfectly match the calculated temperatures.   significant heating is observed in the vicinity of the dark resonances of the zeeman - split s@xmath2-d@xmath3 raman transitions. here   two - photon processes dominate the interaction between lasers and ions.   parameter regimes of laser light are identified that imply most efficient laser cooling.    2
we address the question on how weak perturbations, that are quite ineffective in small many - body systems, can lead to decoherence and hence to irreversibility when they proliferate as the system size increases.   this question is at the heart of solid state nmr.   there, an initially local polarization spreads all over due to spin - spin interactions that conserve the total spin projection, leading to an equilibration of the polarization. in principle, this quantum dynamics can be reversed by changing the sign of the hamiltonian.   however, the reversal is usually perturbed by non reversible interactions that act as a decoherence source.   the fraction of the local excitation recovered defines the loschmidt echo ( le ), here evaluated in a series of closed @xmath0 spin systems with all - to - all interactions.   the most remarkable regime of the le decay occurs when the perturbation induces proliferated effective interactions.   we show that if this perturbation exceeds some lower bound, the decay is ruled by an effective fermi golden rule ( fgr ).   such a lower bound shrinks as @xmath1 increases, becoming the leading mechanism for le decay in the thermodynamic limit.   once the polarization stayed equilibrated longer than the fgr time, it remains equilibrated in spite of the reversal procedure.
by using a markov chain monte carlo simulation, we investigate cosmological constraints on the ghost dark energy ( gde ) model in the framework of the brans - dicke ( bd ) theory. a combination of the latest observational data of the cosmic microwave background radiation data from seven - year wmap, the baryon acoustic oscillation data form the sdss, the supernovae type ia data from the union2 and the x - ray gas mass fraction data from the chandra x - ray observations of the largest relaxed galaxy clusters are used to perform constraints on gde in the bd cosmology.   in this paper, we consider both flat and non - flat universes together with interaction between dark matter and dark energy.   the main cosmological parameters are obtained as : @xmath0, @xmath1 and @xmath2.   in addition, the brans - dicke parameter @xmath3 is estimated as @xmath4.   + _ keywords _ : ghost ; dark energy ; brans - dicke theory ; observational constraints.
aat / wfi optical images of a candidate extragalactic hi cloud, hipass j1712 - 64, are presented.   the g and r - band ccd mosaic camera frames were processed using a new data pipeline recently installed at the aao.   the resultant stacked images reach significantly deeper levels than those of previous published optical imaging of this candidate, providing a detection limit @xmath0 at a distance of 3mpc, the inferred distance to hipass j1712 - 64  . however, detailed analysis of the images fails to uncover any stellar population associated with the hi emission.   if this system is a member of the local group then it is pathologically different to other members.   hence, our observations reinforce earlier suggestions that this hi cloud is most likely galactic in origin and not a local volume dwarf galaxy.   = 2em = 15.5 cm = 22.6 cm = -1.0 cm = 0.5 cm = 0.5 cm    @xmath1 anglo - australian observatory, p.o.   box 296, epping, nsw 1710, australia + gfl@aaoepp.aao.gov.au + @xmath2 institute of astronomy, madingley rd, cambridge, cb3 0 ha, uk + mike@ast.cam.ac.uk + @xmath3 observatoire de strabourg, 11, rue de luniversite, f-67000, strasbourg, france + ibata@pleiades.u-strasbg.fr + @xmath4 centre for astrophysics & supercomputing, swinburne university, po box 218, hawthorn, victoria 3122, australia + bgibson@astro.swin.edu.au +    * keywords
in this paper, we are interested in the estimation and prediction of a parametric model on a short dataset upon which it is expected to overfit and perform badly. to overcome the lack of data ( relatively to the dimension of the model ) we propose the construction of an informative hierarchical bayesian prior based upon another longer dataset which is assumed to share some similarities with the original, short dataset.   we apply the methodology to a working model for the electricity load forecasting on both simulated and real datasets, where it leads to a substantial improvement of the quality of the predictions.   * keywords * : informative prior, hierarchical prior, mcmc algorithms, short dataset, electricity load forecasting
we present a tight - binding potential based on the moment expansion of the density of states, which includes up to the fifth moment.   the potential is fitted to bcc and hcp zr and it is applied to the computation of vibrational properties of bcc - zr. in particular, we compute the isothermal elastic constants in the temperature range @xmath0k by means of standard monte carlo simulation techniques.   the agreement with experimental results is satisfactory, especially in the case of the stability of the lattice with respect to the shear associated with @xmath1.   however, the temperature decrease of the cauchy pressure is not reproduced.   the @xmath2k phonon frequencies of bcc - zr are also computed.   the potential predicts several instabilities of the bcc structure, and a crossing of the longitudinal and transverse modes in the ( 001 ) direction.   this is in agreement with recent ab initio calculations in sc, ti, hf, and la.    #
there is an ever - growing need for predictive models for the elasto - viscoplastic deformation of solids.   our goal in this paper is to incorporate recently developed out - of - equilibrium statistical concepts into a thermodynamically consistent, finite - deformation, continuum framework for deforming amorphous solids.   the basic premise is that the configurational degrees of freedom of the material  the part of the internal energy / entropy that corresponds to mechanically stable microscopic configurations  are characterized by a configurational temperature that might differ from that of the vibrational degrees of freedom, which equilibrate rapidly with an external heat bath.   this results in an approximate internal energy decomposition into weakly interacting configurational and vibrational subsystems, which exchange energy following a fourier - like law, leading to a thermomechanical framework permitting two well - defined temperatures. in this framework,   internal variables that carry information about the state of the material equilibrate with the configurational subsystem, are explicitly associated with energy and entropy of their own, and couple to a viscoplastic flow rule.   the coefficients that determine the rate of flow of entropy and heat between different internal systems are proposed to explicitly depend on the rate of irreversible deformation. as an application of this framework,   we discuss two constitutive models for the response of glassy materials, a simple phenomenological model and a model related to the concept of shear - transformation - zones as the basis for internal variables. the models account for several salient features of glassy deformation phenomenology.   directions for future investigation are briefly discussed.
the measurement of the mixing angle @xmath0, sign of @xmath1 and the cp or t violating phase @xmath2 is fraught with ambiguities in neutrino oscillation. in this paper   we give an analytic treatment of the paramater degeneracies associated with measuring the @xmath3 probability and its cp and/or t conjugates. for cp violation  , we give explicit solutions to allow us to obtain the regions where there exist two - fold and four - fold degeneracies.   we calculate the fractional differences, @xmath4, between the allowed solutions which may be used to compare with the expected sensitivities of the experiments. for t violation   we show that there is always a complete degeneracy between solutions with positive and negative @xmath1 which arises due to a symmetry and can not be removed by observing one neutrino oscillation probability and its t conjugate.   thus, there is always a four fold parameter degeneracy apart from exceptional points.   explicit solutions are also given and the fractional differences are computed.   the bi - probability cp / t trajectory diagrams are extensively used to illuminate the nature of the degeneracies.   # 1#1    = 23 cm = -1.4 cm
there is evidence that the transiting planet hd  209458b has a large exosphere of neutral hydrogen, based on a 15% decrement in lyman-@xmath0 flux that was observed by vidal - madjar et al.  during transits.   here we report upper limits on h@xmath0 absorption by the exosphere.   the results are based on optical spectra of the parent star obtained with the subaru high dispersion spectrograph.   comparison of the spectra taken inside and outside of transit reveals no exospheric h@xmath0 signal greater than 0.1% within a 5.1  band ( chosen to have the same @xmath1 as the 15% ly@xmath0 absorption ).   the corresponding limit on the column density of @xmath2 neutral hydrogen is @xmath3  @xmath4.   this limit constrains proposed models involving a hot ( @xmath510@xmath6  k ) and hydrodynamically escaping exosphere.
star - forming galaxies at high redshifts are the ideal targets to probe the hypothetical variation of the fine - structure constant @xmath0 over cosmological time scales.   we propose a modification of the alkali doublets method which allows us to search for variation in @xmath0 combining far infrared and submillimeter spectroscopic observations.   this variation manifests as velocity offsets between the observed positions of the fine - structure and gross - structure transitions when compared to laboratory wavelengths.   here we describe our method whose sensitivity limit to the fractional changes in @xmath0 is about @xmath1. we also demonstrate that current spectral observations of hydrogen and  158 @xmath2 m lines provide an upper limit on @xmath3 at redshifts @xmath4 and @xmath5.       methods : observational  techniques : spectroscopic  galaxies : high - redshift  cosmology : observations
tapered and dispersion managed ( dm ) silicon nanophotonic waveguides are investigated for the generation of optimal ultra broadband supercontinuum ( sc ).   dm waveguides are structures showing a longitudinally dependent group velocity dispersion that results from the variation of the waveguide width with the propagation distance. for the generation of optimal sc  , a genetic algorithm has been used to find the best dispersion map.   this allows for the generation of highly coherent supercontinuums that span over 1.14 octaves from 1300  nm to 2860  nm and 1.25 octaves from 1200  nm to 2870  nm at -20  db level for the tapered and dm waveguides respectively, for a 2@xmath0 m, 200 fs and 6.4 pj input pulse.   the comparison of these two structures with the usually considered optimal fixed width waveguide shows that the sc is broader and flatter in the more elaborated dm waveguide, while the high coherence is ensured by the varying dispersion.
data clustering, including problems such as finding network communities, can be put into a systematic framework by means of a bayesian approach.   the application of bayesian approaches to real problems can be, however, quite challenging. in most cases   the solution is explored via monte carlo sampling or variational methods.   here we work further on the application of variational methods to clustering problems.   we introduce generative models based on a hidden group structure and prior distributions.   we extend previous attends by jaynes, and derive the prior distributions based on symmetry arguments. as a case study   we address the problems of two - sides clustering real value data and clustering data represented by a hypergraph or bipartite graph. from the variational calculations, and depending on the starting statistical model for the data, we derive a variational bayes algorithm, a generalized version of the expectation maximization algorithm with a built in penalization for model complexity or bias.   we demonstrate the good performance of the variational bayes algorithm using test examples.
we derive an extended version of the well - known lyth bound on the total variation of the inflaton field, incorporating higher order corrections in slow roll.   we connect the field variation @xmath0 to both the spectral index of scalar perturbations and the amplitude of tensor modes.   we then investigate the implications of this bound for `` small field '' potentials, where the field rolls off a local maximum of the potential.   the total field variation during inflation is _ generically _ of order @xmath1, even for potentials with a suppressed tensor / scalar ratio.   much of the total field excursion arises in the last e - fold of inflation and in single field models this problem can only be avoided via fine - tuning or the imposition of a symmetry.   finally, we discuss the implications of this result for inflationary model building in string theory and supergravity.
using the chandra high energy transmission grating spectrometer ( hetgs ), we have found significant absorption features in the x - ray spectrum of cyg x-1 taken in the continuous clocking mode.   these features include resonance lines of he - like ions of s, si, and mg ; the ly alpha lines of h - like s, si, mg, and ne ; and several lower ionization lines of fe xx, xxii, and xxiv.   preliminary analysis shows that the lines are resolved in many cases, giving line widths of order 300 km / s and are redshifted by 460 @xmath0 10 km / s.   these features are interpreted in the context of an accreting stellar wind model that is ionized by the x - ray source.   in addition, there are clear absorption features due to neutral mg, fe, and o in the interstellar medium.
it has recently been demonstrated that self - consistent particle - in - cell simulations of low - obliquity pulsar magnetospheres in flat spacetime show weak particle acceleration and no pair production near the poles.   we investigate the validity of this conclusion in a more realistic spacetime geometry via general - relativistic particle - in - cell simulations of the aligned pulsar magnetospheres with pair formation.   we find that the addition of frame - dragging effect makes local current density along the magnetic field larger than the goldreich - julian value, which leads to unscreened parallel electric fields and the ignition of a pair cascade.   when pair production is active, we observe field oscillations in the open field bundle which could be related to pulsar radio emission.   we conclude that general relativistic effects are essential for the existence of pulsar mechanism in low obliquity rotators.
we report the measurement of the directed flow ( @xmath0 ) for charged kaons in au+au collisions at @xmath1 = 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 gev as a function of rapidity and compare these results for pions, protons and antiprotons.   these new kaon results may help to constrain the medium properties and collision dynamics including the in - medium kaon potential and baryon number transport in these collisions.
quantitative constraints on the wind clumping of massive stars can be obtained from the study of the hard x - ray variability of sfxts. in these systems, a large fraction of the hard x - ray emission is emitted in the form of flares with typical duration of 3 ksec, frequency of 7 days and luminosity of @xmath0 ergs / s.   such flares are most probably emitted by the interaction of a compact object orbiting at @xmath1 with wind clumps ( @xmath2 g ).   the density ratio between the clumps and the inter - clump medium is @xmath3.   the parameters of the clumps and of the inter - clump medium are in good agreement with macro - clumping scenario and line - driven instability simulations.
neutrino oscillations are at the forefront of advances in physics beyond the standard model.   increasing accuracy in measurements of the neutrino mixing matrix is an important challenge in current experiments.   it depends on parameters that do not directly correspond to observables of the neutrino system.   this type of estimation problem is handled by quantum estimation theory ( qet ) via the fisher information ( fi ) and the quantum fisher information ( qfi ).  in this work,   we analyze two - flavor neutrino oscillations within the framework of qet.   we compute the qfi for the mixing angle @xmath0 and show that mass measurements are the ones that achieve optimal precision.   we also study the fi associated with flavor measurements and show that they are optimized at specific neutrino times - of - flight.  therefore, although the usual population measurement does not realize the precision limit set by the qfi, it can in principle be implemented with the best possible sensitivity to @xmath1.   we study how these quantifiers relate to the single - particle, mode entanglement.   we demonstrate that this form of entanglement does not enhance neither of them.   in particular, this shows that in single - particle settings, entanglement is not directly connected with the optimal precision in metrological tasks.
a less well known variant of the nambu  jona - lasinio model with @xmath0 colors and u(2)@xmath1u(2)@xmath2 chiral symmetry is studied in 1 + 1 dimensions. using semi - classical methods appropriate for the large @xmath0 limit  , we determine the vacuum manifold, the meson spectrum, massless and massive multi - fermion bound states and the phase diagram as a function of temperature, chemical potential and isospin chemical potential. an important tool to understand soliton dynamics is the generalization of the time - dependent hartree - fock approach to two flavors along the lines recently developed by takahashi in the context of unconventional fermionic superfluids and superconductors.
this paper is a continuation of our previous analysis ( i.e. turyshev 2002a, 2002b ) of the relativistic stellar aberration requirements for the space interferometry mission ( sim ).   here we have considered a problem of how the expected astrometric accuracy of parallax determination will constrain the accuracy of the spacecraft navigation.   we show that effect of the spacecraft s navigational errors on the accuracy of parallax determination with sim will be negligible.   we discuss the implication of the results obtained for the future mission analysis.
we consider the problem of consumption of stars by a supermassive black hole ( sbh ) at the center of an axisymmetric galaxy. inside the sbh  sphere of influence, motion of stars in the mean field   is regular and can be described analytically in terms of three integrals of motion : the energy @xmath0, the @xmath1-component of angular momentum @xmath2, and the secular hamiltonian @xmath3.   there exist two classes of orbits, tubes and saucers ; saucers occupy the low - angular - momentum parts of phase space and their fraction is proportional to the degree of flattening of the nucleus.   perturbations due to gravitational encounters lead to diffusion of stars in integral space, which can be described using the fokker - planck equation.   we calculate the diffusion coefficients and solve this equation in the two - dimensional phase space ( @xmath4 ), for various values of the capture radius and the degree of flattening.   capture rates are found to be modestly higher than in the spherical case, up to a factor of a few, and most captures take place from saucer orbits.   we also carry out a set of collisional @xmath5-body simulations to confirm the predictions of the fokker - planck models.   we discuss the implications of our results for rates of tidal disruption and capture in the milky way and external galaxies.
evidence of azimuthal asymmetries in the time structure and signal size have been found in non - vertical showers at the pierre auger observatory.   it has been previously shown that the asymmetry in time distributions offers a new possibility for the determination of the mass composition.   new studies have demonstrated that the dependence of the asymmetry parameter in the rise - time and fall - time distributions with @xmath0 shows a clear peak.   both, the position of the peak, @xmath1, and the size of the asymmetry at @xmath1 are sensitive to primary mass composition and have a small dependence on energy. in this paper a study of the discriminating power of the new observables to separate primary species is presented.
noise is a problem of major concern for @xmath0-body simulations of structure formation in the early universe, of galaxies and plasmas. here for the first time we use wavelets to remove noise from @xmath0-body simulations of disc galaxies, and show that they become equivalent to simulations with two orders of magnitude more particles.   we expect a comparable improvement in performance for cosmological and plasma simulations. our wavelet code will be described in a following paper, and will then be available on request.       plasmas  methods : @xmath0-body simulations  methods : numerical  galaxies : general  galaxies : kinematics and dynamics  cosmology : miscellaneous.
we use an importance sampling ( is ) type correction of approximate markov chain monte carlo ( mcmc ) output in order to provide consistent estimators.   the is approach, based on unbiased estimators, provides often a natural alternative to delayed acceptance ( da ) mcmc, but contrary to da - mcmc, benefits from straightforward parallelisation.   we focus on the case where the mcmc simulation is conducted on an approximate marginal distribution, and the is type correction leads to consistent inference on the corresponding joint distribution.   such a case allows for importance sampling analogues of pseudo - marginal type mcmc methods, such as the grouped independence metropolis - hastings and the particle marginal metropolis - hastings.   we prove strong consistency of the suggested estimators under mild assumptions, and provide central limit theorems with expressions for asymptotic variances.   the methods are illustrated in practice with state space models, where we also remind that is correction provides an easy way to combine several independent particle smoothers in order to obtain a consistent estimator with natural confidence intervals.   our experimental results are promising and show that is type approach can be favourable against a computationally comparable da scheme.
we present some results of numerical simulations of a globular cluster orbiting in the central region of a triaxial galaxy on a set of loop orbits.   tails start forming after about a quarter of the globular cluster orbital period and develop, in most cases, along the cluster orbit, showing clumpy substructures as observed, for example, in palomar 5.   if completely detectable, clumps can contain about @xmath0 each, i.e. about @xmath1 of the cluster mass at that epoch.   the morphology of tails and clumps and the kinematical properties of stars in the tails are studied and compared with available observational data.   our finding is that the stellar velocity dispersion tends to level off at large radii, in agreement to that found for m15 and @xmath2 centauri.
the linear dispersion relation for surface perturbations, as derived by levine _ et al. _, _ _ phys.   rev. b__@xmath0 * 75 *, 205312 ( 2007 ) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength ( from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding wulff shape ). through detailed parametric studies   it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained solid films.   + pacs : 68.55.j, morphology of films ; 81.15.aa, theory and models of film growth ; 81.16.dn, self - assembly.
shear yielding of glassy polymers is usually described in terms of the pressure - dependent tresca or von mises yield criteria.   we test these criteria against molecular dynamics simulations of deformation in amorphous polymer glasses under triaxial loading conditions that are difficult to realize in experiments.   difficulties and ambiguities in extending several standard definitions of the yield point to triaxial loads are described.   two definitions, the maximum and offset octahedral stresses, are then used to evaluate the yield stress for a wide range of model parameters. in all cases,   the onset of shear is consistent with the pressure - modified von mises criterion, and the pressure coefficient is nearly independent of many parameters. under triaxial tensile loading  , the mode of failure changes to cavitation.    2
an exponentially expanding universe, possibly governed by a cosmological constant, forces gravitationally bound structures to become more and more isolated, eventually becoming causally disconnected from each other and forming so - called  island universes ".   this new scenario reformulates the question about which will be the largest structures that will remain gravitationally bound, together with requiring a systematic tool that can be used to recognize the limits and mass of these structures from observational data, namely redshift surveys of galaxies. here   we present a method, based on the spherical collapse model and @xmath0-body simulations, by which we can estimate the limits of bound structures as observed in redshift space.   the method is based on a theoretical criterion presented in a previous paper that determines the mean density contrast that a spherical shell must have in order to be marginally bound to the massive structure within it.   understanding the kinematics of the system, we translated the real - space limiting conditions of this  critical " shell to redshift space, producing a projected velocity envelope that only depends on the density profile of the structure. from it   we created a redshift - space version of the density contrast that we called  density estimator ", which can be calibrated from @xmath0-body simulations for a reasonable projected velocity envelope template, and used to estimate the limits and mass of a structure only from its redshift - space coordinates.       methods : @xmath0-body simulations  large - scale structure of universe  galaxies : clusters : general  galaxies : kinematics and dynamics
loop quantum cosmology is an application of recent developments for a non - perturbative and background independent quantization of gravity to a cosmological setting.   characteristic properties of the quantization such as discreteness of spatial geometry entail physical consequences for the structure of classical singularities as well as the evolution of the very early universe. while the singularity issue in general requires one to use difference equations for a wave function of the universe, phenomenological scenarios for the evolution are based on effective equations implementing the main quantum modifications.   these equations show generic bounces as well as inflation in diverse models, which have been combined to more complicated scenarios.
we analyze the response of a nanomechanical resonator to an external drive when it is also coupled to a single - electron transistor ( set ).   the interaction between the set electrons and the mechanical resonator depends on the amplitude of the mechanical motion leading to a strongly non - linear response to the drive which is similar to that of a duffing oscillator.   we show that the average dynamics of the resonator is well described by a simple effective model which incorporates damping and frequency renormalization terms which are amplitude dependent.   we also find that for a certain range of parameters the system displays interesting bistable dynamics in which noise arising from charge fluctuations causes the resonator to switch slowly between different dynamical states.
mechanisms for particle production at intermediate @xmath0 in nuclear collisions at rhic are discussed, emphasizing the differences in associated jet - like correlations between color - neutral and colored production.   an alternative production mechanism involving both recombination and fragmentation is suggested, which might simultaneously lead to an enhancement of baryons and to jet - like correlations. to gain more insight into the relative importance of different mechanisms a study of constrained distributions of associated multiplicity   is proposed. in a simple model   it is shown that these multiplicity distributions may change significantly, if the nature of the production mechanism fluctuates from event to event.   .
we consider the effects of doping the @xmath0 = 1/2 kagome lattice with static impurities. we demonstrate that impurities lower the number of low  lying singlet states, induce dimer   dimer correlations of considerable spatial extent, and do not generate free spin degrees of freedom.   most importantly, they experience a highly unconventional mutual repulsion as a direct consequence of the strong spin frustration.   these properties are illustrated by exact diagonalization, and reproduced to semi  quantitative accuracy within a dimer resonating  valence   bond description which affords access to longer length scales.   we calculate the local magnetization induced by doped impurities, and consider its implications for nuclear magnetic resonance measurements on known kagome systems.
we use both an hi - selected and an optically - selected galaxy sample to directly measure the abundance of galaxies as a function of their `` baryonic '' mass ( stars + atomic gas ).   stellar masses are calculated based on optical data from the sloan digital sky survey ( sdss ) and atomic gas masses are calculated using atomic hydrogen ( hi ) emission line data from the arecibo legacy fast alfa ( alfalfa ) survey. by using the technique of abundance matching,   we combine the measured baryonic function ( bmf ) of galaxies with the dark matter halo mass function in a @xmath0cdm universe, in order to determine the galactic baryon fraction as a function of host halo mass.   we find that the baryon fraction of low - mass halos is much smaller than the cosmic value, even when atomic gas is taken into account.   we find that the galactic baryon deficit increases monotonically with decreasing halo mass, in contrast with previous studies which suggested an approximately constant baryon fraction at the low - mass end.   we argue that the observed baryon fractions of low mass halos can not be explained by reionization heating alone, and that additional feedback mechanisms ( e.g. supernova blowout ) must be invoked.   however, the outflow rates needed to reproduce our result are not easily accommodated in the standard picture of galaxy formation in a @xmath0cdm universe.
a _ box _ in euclidean @xmath0-space is the cartesian product @xmath1, where @xmath2 is a closed interval on the real line.   the _ boxicity _ of a graph @xmath3, denoted by @xmath4, is the minimum integer @xmath0 such that @xmath3 can be represented as the intersection graph of a family of boxes in euclidean @xmath0-space.   + in this paper, we observe behavior of the boxicity of generalized mycielski graphs.   here   we consider whether the boxicity of the generalized mycielski graph @xmath5 is more than that of @xmath3  .   actually, the inequality @xmath6 holds for a graph @xmath3.   we give a lower bound for the boxicity of generalized mycielski graphs.   we prove that @xmath7 holds for a graph @xmath3 with @xmath8 focal vertices.   this indicates that the boxicity of the generalized mycielski graph @xmath5 is more than that of @xmath3 if @xmath3 has a focal vertex.   moreover, we also present an upper bound for the boxicity of mycielski graphs.   for a graph @xmath3 with @xmath8 focal vertices, we prove that @xmath9 holds, where @xmath10 is the _ edge clique cover number _ of the complement @xmath11.   these results determine the boxicity of mycielski graphs of some of complete @xmath0-partite graphs.   + * keywords * : boxicity ; chromatic number ; cointerval graph ; edge clique cover number ; ( generalized ) mycielski graph
we consider the kuramoto model of globally coupled phase oscillators with time - delayed interactions, that is subject to the ornstein - uhlenbeck ( gaussian ) colored or the non - gaussian colored noise.   we investigate numerically the interplay between the influences of the finite correlation time of noise @xmath0 and the time delay @xmath1 on the onset of the synchronization process.   both cases for identical and nonidentical oscillators had been considered. among the obtained results for identical oscillators   is a large increase of the synchronization threshold as a function of time delay for the colored non - gaussian noise compared to the case of the colored gaussian noise at low noise correlation time @xmath0.   however, the difference reduces remarkably for large noise correlation times. for the case of nonidentical oscillators, the incoherent state may become unstable around the maximum value of the threshold ( as a function of time delay ) even at lower coupling strength values in the presence of colored noise as compared to the noiseless case.   we had studied the dependence of the critical value of the coupling strength ( the threshold of synchronization ) on given parameters of the stochastic kuramoto model in great details and presented results for possible cases of colored gaussian and non - gaussian noises.
to obtain a high degree of long - term length stabilisation of an optical reference cavity, its free - spectral range is locked by means of an accurate and stable frequency synthesizer.   the locking scheme is twofold : a laser is locked on the n@xmath0 mode of a reference fabry - perot cavity and part of the laser light is shifted in frequency to be in resonance with the ( n+1)@xmath0 mode of the cavity.   this shift is generated by an acousto - optical modulator ( aom ) mounted in a double - pass scheme, matching half of the free spectral range of the reference cavity.   the resulting absolute stabilization of the length of the cavity reaches the 10@xmath1 level per second, limited by the lock transfer properties and the frequency stability of the aom control synthesizer.
these notes are based on the lectures delivered at the les houches summer school in july 2015.   they are addressed at a mixed audience of physicists and mathematicians with some basic working knowledge of random matrix theory. the first part is devoted to the solution of the chiral gaussian unitary ensemble in the presence of characteristic polynomials, using orthogonal polynomial techniques.   this includes all eigenvalue density correlation functions, smallest eigenvalue distributions and their microscopic limit at the origin.   these quantities are relevant for the description of the dirac operator spectrum in quantum chromodynamics with three colours in four euclidean space - time dimensions. in the second part   these two theories are related based on symmetries, and the random matrix approximation is explained. in the last part   recent developments are covered including the effect of finite chemical potential and finite space - time lattice spacing, and their corresponding orthogonal polynomials.   we also give some open random matrix problems.   -1.4 cm -0.8 cm -0.8 cm
the present knowledge of the structure of the photon is presented based on results obtained by measurements of photon structure functions at e@xmath0e@xmath1 collider.   results are presented both for the qed structure of the photon as well as for the hadronic structure, where the data are also compared to recent parametrisations of the hadronic structure function.   prospects of future photon structure function measurements, especially at an international linear collider are outlined.   * mpp-2009 - 131 *
the problem of characterizing complexity of quantum dynamics - in particular of locally interacting chains of quantum particles - will be reviewed and discussed from several different perspectives : ( i ) stability of motion against external perturbations and decoherence, ( ii ) efficiency of quantum simulation in terms of classical computation and entanglement production in operator spaces, ( iii ) quantum transport, relaxation to equilibrium and quantum mixing, and ( iv ) computation of quantum dynamical entropies.   discussions of all these criteria will be confronted with the established criteria of integrability or quantum chaos, and sometimes quite surprising conclusions are found.   some conjectures and interesting open problems in ergodic theory of the quantum many problem are suggested.   _ invited review article for special issue of journal of physics a on quantum information _
we demonstrate and contrast two approaches to the stabilization of qubit entanglement by feedback.   our demonstration is built on a feedback platform consisting of two superconducting qubits coupled to a cavity which are measured by a nearly - quantum - limited measurement chain and controlled by high - speed classical logic circuits.   this platform is used to stabilize entanglement by two nominally distinct schemes : a `` passive '' reservoir engineering method and an `` active '' correction based on conditional parity measurements. in view of the instrumental roles that these two feedback paradigms play in quantum error - correction and quantum control, we directly compare them on the same experimental setup.   further, we show that a second layer of feedback can be added to each of these schemes, which heralds the presence of a high - fidelity entangled state in real - time.   this `` nested '' feedback brings about a marked entanglement fidelity improvement without sacrificing success probability.
a unified model of electron penetration into linear plasma wakefields is formulated and studied. the optimum angle for side injection of electrons is found. at smaller angles,   all electrons are reflected radially. at larger angles,   electrons enter the wakefield with superfluous transverse momentum that is unfavorable for trapping.   separation of incident electrons into penetrated and reflected fractions occur in the outer region of the wakefield at some `` reflection '' radius that depends on the electron energy.
using the photometric redshifts of galaxies from the sloan digital sky survey iii ( sdss - iii ), we identify 132,684 clusters in the redshift range of @xmath0.   monte carlo simulations show that the false detection rate is less than 6% for the whole sample.   the completeness is more than 95% for clusters with a mass of @xmath1 in the redshift range of @xmath2, while clusters of @xmath3 are less complete and have a biased smaller richness than the real one due to incompleteness of member galaxies.   we compare our sample with other cluster samples, and find that more than 90% of previously known rich clusters of @xmath4 are matched with clusters in our sample.   richer clusters tend to have more luminous brightest cluster galaxies ( bcgs ).   correlating with x - ray and the planck data, we show that the cluster richness is closely related to the x - ray luminosity, temperature, and sunyaev  zeldovich measurements.   comparison of the bcgs with the sdss luminous red galaxy ( lrg ) sample shows that 25% of lrgs are bcgs of our clusters and 36% of lrgs are cluster member galaxies. in our cluster sample, 63% of bcgs of @xmath5   satisfy the sdss lrg selection criteria.
this work addresses a procedure to estimate fundamental stellar parameters such as @xmath0, log__g _ _, , and @xmath1 using a dimensionality reduction technique called principal component analysis ( pca ), applied to a large database of synthetic spectra.   this technique shows promising results for inverting stellar parameters of observed targets from gaia eso survey.   stars : fundamental parameters, techniques : spectroscopic
we derive the quantum trajectory or stochastic ( conditional ) master equation for a single superconducting cooper - pair box ( scb ) charge qubit measured by a single - electron transistor ( set ) detector.   this stochastic master equation describes the random evolution of the measured scb qubit density matrix which both conditions and is conditioned on a particular realization of the measured electron tunneling events through the set junctions.   hence it can be regarded as a monte carlo method that allows us to simulate the continuous quantum measurement process.   we show that the master equation for the `` partially '' reduced density matrix [ y.  makhlin et.al.  , phys.   rev.   lett. * 85 *, 4578 ( 2000 ) ] can be obtained when a `` partial '' average is taken on the stochastic master equation over the fine grained measurement records of the tunneling events in the set. finally, we present some monte carlo simulation results for the scb / set measurement process.   we also analyze the probability distribution @xmath0 of finding @xmath1 electrons that have tunneled into the drain of the set in time @xmath2 to demonstrate the connection between the quantum trajectory approach and the `` partially '' reduced density matrix approach.
probabilistic graphical models such as bayesian networks are one of the most powerful structures known by the computer science community for deriving probabilistic inferences.   however, modern cognitive psychology has revealed that human decisions could not follow the rules of classical probability theory, because humans can not process large amounts of data in order to make judgements.   consequently, the inferences performed are based on limited data coupled with several heuristics, leading to violations of the law of total probability.   this means that probabilistic graphical models based on classical probability theory are too limited to fully simulate and explain various aspects of human decision making.   quantum probability theory was developed in order to accommodate the paradoxical findings that the classical theory could not explain.   recent findings in cognitive psychology revealed that quantum probability can fully describe human decisions in an elegant framework.   their findings suggest that, before taking a decision, human thoughts are seen as superposed waves that can interfere with each other, influencing the final decision.    in this work  , we propose a new bayesian network based on the psychological findings of cognitive scientists.   we made experiments with two very well known bayesian networks from the literature.   the results obtained revealed that the quantum like bayesian network can affect drastically the probabilistic inferences, specially when the levels of uncertainty of the network are very high ( no pieces of evidence observed ).   when the levels of uncertainty are very low, then the proposed quantum like network collapses to its classical counterpart.
we discuss the properties of a strongly interacting spin - charge separated one dimensional system coupled to ferromagnets and/or superconductors.   our results are valid for arbitrary temperatures with respect to the spin energy, but require temperature be small compared to the charge energy.   we focus mainly on the spin - incoherent regime where temperature is large compared to the spin energy, but small compared to the charge energy. in the case of a ferromagnet we study spin pumping and the renormalized dynamics of a precessing magnetic order parameter.   we find the interaction - dependent temperature dependence of the spin pumping can be qualitatively different in the spin - incoherent regime from the luttinger liquid regime, allowing an identification of the former.   likewise, the temperature dependence of the renormlized magnetization dynamics can be used to identify spin - incoherent physics. for the case of a spin - incoherent luttinger liquid   coupled to two superconductors, we compute the ac and dc josephson current for a wire geometry in the limit of tunnel coupled superconductors. both the ac and dc response contain  smoking gun " signatures that can be used to identify spin - incoherent behavior.   experimental requirements for the observation of these effects are laid out.
in this paper, we present the design, implementation and our year - long maintenance experience of snsapi, a python - based middleware which unifies the interfaces and data structures of heterogeneous social networking services ( sns ). unlike most prior works,   our middleware is user - oriented and requires zero infrastructure support.   it enables a user to readily conduct online social activities in a programmable, cross - platform fashion while gradually reducing the dependence on centralized online social networks ( osn ).   more importantly, as the snsapi middleware can be used to support decentralized social networking services via conventional communication channels such as rss or email, it enables the deployment of decentralized social networks ( dsn ) in an incremental, ad hoc manner. to demonstrate the viability of such type of dsns  , we have deployed an experimental 6000-node snsapi - based dsn on planetlab and evaluate its performance by replaying traces of online social activities collected from a mainstream osn.   our results show that, with only mild resource consumption, the snsapi - based dsn can achieve acceptable forwarding latency comparable to that of a centralized osn.   we also develop an analytical model to characterize the trade - offs between resource consumption and message forwarding delay in our dsn. via 20 parameterized experiments on planetlab  , we have found that the empirical measurement results match reasonably with the performance predicted by our analytical model.
we present v and i photometry of a @xmath0 field centered on the dwarf spheroidal galaxy leo  i. the i magnitude of the tip of the red giant branch is robustly estimated from two different datasets ( @xmath1 ). from this estimate, adopting @xmath2\simeq-1.2 $ ] from the comparison of rgb stars with galactic templates, we obtain a distance modulus @xmath3, corresponding to a distance @xmath4 kpc.       stars : population ii - galaxies : distances and redshifts - local group
as for other areas in modern astronomy, the ska will revolutionize the field of pulsar astrophysics. not only will new science be possible by the shear number of pulsars discovered, but also by the unique timing precision achievable with the ska.   the combination of both will not simply mean a continuation of the successes already achieved by using pulsars as fundamental tools of physics but the ska will provide a new quality of science.
the dynamics of the one - tangle and the concurrence is analyzed in the lipkin - meshkov - glick model which describes many physical systems such as the two - mode bose - einstein condensates.   we consider two different initial states which are physically relevant and show that their entanglement dynamics are very different.   a semiclassical analysis is used to compute the one - tangle which measures the entanglement of one spin with all the others, whereas the frozen - spin approximation allows us to compute the concurrence using its mapping onto the spin squeezing parameter.
we compare the capability of wavelet functions used for noise removal in preprocessing step of a qrs detection algorithm in the electrocardiogram ( ecg ) signal.   the qrs signal to noise ratio enhancement and the detection accuracy of each wavelet function are evaluated using three measures : ( 1 ) the ratio of the maximum beat amplitude to the minimum beat amplitude ( rmm ), ( 2 ) the mean of absolute of time error ( mate ), and ( 3 ) the figure of merit ( fom ).   three wavelet functions from previous well - known publications are explored, i.e., bior1.3, db10, and mexican hat wavelet functions.   results evaluated with the ecg signal from mit - bih arrhythmia database show that the mexican hat wavelet function is better than the others. while the scale 8 of mexican hat wavelet function can provide the best enhancement in qrs signal to noise ratio  , the scale 4 of mexican hat wavelet function can provide the best detection accuracy.   these results may be combined and may enable the use of a single fixed threshold for all ecg records leading to the reduction in computational complexity of the qrs detection algorithm.
observations of clusters in the 30 to 350 ghz range can in principle be used to determine a galaxy cluster s comptonization parameter, @xmath0, peculiar velocity, @xmath1 and gas temperature, @xmath2 via the dependence of the kinetic and thermal sunyaev - zeldovich ( sz ) effects on these parameters. despite the significant contamination expected from thermal emission by dust in high - redshift galaxies,   we find that the simultaneous determination of @xmath3, @xmath1 and @xmath2 is possible from observations with sensitivity of a few @xmath4k in three or more bands with arc minute resolution. after allowing for realistic levels of contamination by dusty galaxies and primary cmb anisotropy  , we find that simultaneous determinations of velocities to an accuracy of better than 200 @xmath5 and temperatures to roughly kev accuracy should be possible in the near future.   we study how errors change as a function of cluster properties ( angular core radius and gas temperature ) and experimental parameters ( observing time, angular resolution and observing frequencies ). contaminating synchrotron emission from cluster galaxies will probably not be a major contaminant of peculiar velocity measurements.
precision radial velocities from the automated planet finder and keck / hires reveal an @xmath0 planet orbiting the nearby m3v star gj  687.   this planet has an orbital period, @xmath1 days, and a low orbital eccentricity.   our strmgren b and y photometry of the host star suggests a stellar rotation signature with a period of @xmath2 = 60 days.   the star is somewhat chromospherically active, with a spot filling factor estimated to be several percent.   the rotationally  induced 60-day signal, however, is well - separated from the period of the radial velocity variations, instilling confidence in the interpretation of a keplerian origin for the observed velocity variations.   although gj  687  b produces relatively little specific interest in connection with its individual properties, a compelling case can be argued that it is worthy of remark as an _ eminently typical _, yet at a distance of 4.52  pc, a very nearby representative of the galactic planetary census.   the detection of gj  687  b indicates that the apf telescope is well suited to the discovery of low - mass planets orbiting low - mass stars in the as - yet relatively un - surveyed region of the sky near the north celestial pole.
we present the results of 7 years of @xmath0-band monitoring of the low - mass x - ray binary grs 1915 + 105.   positive correlations between the infrared flux and the x - ray flux and x - ray hardness are demonstrated.   analysis of the frequency spectrum shows that the orbital period of the system is @xmath1 days.   the phase and amplitude of the orbital modulation suggests that the modulation is due to the heating of the face of the secondary star.   we also report another periodic signature between 31.2 and 31.6 days, most likely due to a superhump resonance. from the superhump period   we then obtain a range for the mass ratio of the system, @xmath2.
it is widely accepted that the doppler deboosting effects exist in counter relativistic jets. however  , people often neglect another important fact that both doppler boosting and deboosting effects could happen in forward relativistic jets.   such effects might be used to explain some strange phenomena, such as the invisible gaps between the inner and outer jets of agns, and the rapid initial decays and re - brightening bumps in the light curves of grbs.
_ chandra _  high - energy transmission grating observations of the bright eclipsing contact binary 44_@xmath0 _  boo  show x - ray line profiles which are doppler - shifted by orbital motions.   the x - ray emission spectrum contains a multitude of lines superimposed on a weak continuum, with strong lines of,,, and.   the profiles of these lines from the total observed spectrum show doppler - broadened widths of @xmath1 km s@xmath2.   line centroids vary with orbital phase, indicating velocity changes of @xmath3 km s@xmath2.   the first - order light curve shows significant variability, but no clear evidence for either primary or secondary eclipses.   flares are observed for all spectral ranges ; additionally, the light curve constructed near the peak of the emission measure distribution ( @xmath4 to @xmath5 k ) shows quiescent variability as well as flares.   the phase - dependences of line profiles and light curves together imply that at least half of the emission is localized at high latitude.   a simple model with two regions on the primary star at relatively high latitude reproduces the observed line profile shifts and quiescent light curve.   these first clear x - ray doppler shifts of stellar coronal material illustrate the power of _ chandra_.
what is the optimal shape of a dendrite?   of course, optimality refers to some particular criterion. in this paper, we look at the case of a dendrite sealed at one end and connected at the other end to a soma.   the electrical potential in the fiber follows the classical cable equations as established by w. rall.   we are interested in the shape of the dendrite which minimizes either the attenuation in time of the potential or the attenuation in space. in both cases,   we prove that the cylindrical shape is optimal.
bottomonium measurements provide unique insight into hot and cold nuclear matter effects present in the medium that is formed in high - energy heavy - ion collisions.   recent star results show that in @xmath0 gev central au+au collisions the @xmath1(1s ) state is suppressed more than the case that if only cold nuclear matter effects were present, and the excited state yields are consistent with a complete suppression. in 2012, star also collected 263.4 @xmath2b@xmath3 high - energy - electron triggered data in u+u collisions at @xmath4 gev.   central u+u collisions, with an estimated 20% higher energy density than that in central au+au data, extend the @xmath1(1s+2s+3s ) and @xmath1(1s ) nuclear modification trends observed in au+au towards higher number of participant nucleons, and confirm the suppression of the @xmath1(1s ) state.   we see a hint with 1.8 @xmath5 significance that the @xmath1(2s+3s ) excited states are not completely suppressed in u+u collisions.   these data support the sequential in - medium quarkonium dissociation picture and favor models with a strong @xmath6 binding.   = 1    brookhaven rhic coll, quarkonium : heavy, quarkonium : production, quark gluon : plasma
in the standard supernova picture, type ib / c and type ii supernovae are powered by the potential energy released in the collapse of the core of a massive star. in studying supernovae  , we primarily focus on the ejecta that makes it beyond the potential well of the collapsed core.   but, as we shall show in this paper, in most supernova explosions, a tenth of a solar mass or more of the ejecta is decelerated enough that it does not escape the potential well of that compact object.   this material falls back onto the proto - neutron star within the first 10 - 15 seconds after the launch of the explosion, releasing more than @xmath0erg of additional potential energy.   most of this energy is emitted in the form of neutrinos and we must understand this fallback neutrino emission if we are to use neutrino observations to study the behavior of matter at high densities. here   we present both a 1-dimensional study of fallback using energy - injected, supernova explosions and a first study of neutrino emission from fallback using a suite of 2-dimensional simulations.
ground - based gamma - ray astronomy has experienced a major breakthrough in the last decade thanks to the advent of new generation instruments such as h.e.s.s., magic, milagro and veritas.   a large variety of cosmic particle accelerators has been unveiled, comprising supermassive black holes in the centres of active galaxies, nearby star forming galaxies, galactic supernova remnants and pulsar wind nebulae, and stellar binary systems housing a compact object. while current instruments revealed the tips of the non - thermal icebergs in our universe, a factor of 10 increase in sensitivity, improved angular resolution and an extended energy coverage   is required to fully explore and understand the physics of cosmic particle acceleration.   the cherenkov telescope array ( cta ) will provide these performances, by deploying two arrays of cherenkov telescopes in the northern and southern hemispheres, allowing full - sky coverage. in this paper   we summarize the project status and present the science prospects of the cta observatory.   address = cesr, cnrs / ups, - 9, avenue du colonel roche, 31028 toulouse, france
we present a new approach to calculate excited states with the full configuration interaction quantum monte carlo ( fciqmc ) method.   the approach uses a gram - schmidt procedure, instantaneously applied to the stochastically evolving distributions of walkers, to orthogonalize higher energy states against lower energy ones.   it can thus be used to study several of the lowest - energy states of a system within the same symmetry.   this additional step is particularly simple and computationally inexpensive, requiring only a small change to the underlying fciqmc algorithm.   no trial wave functions or partitioning of the space is needed.   the approach should allow excited states to be studied for systems similar to those accessible to the ground - state method, due to a comparable computational cost.   as a first application we consider the carbon dimer in basis sets up to quadruple - zeta quality, and compare to existing results where available.
a spin filtering device through quantum spin interference is addressed, in two dimensions, in a gaas / algaas electron gas that has both rashba and dresselhaus spin - orbit couplings and an applied external magnetic field.   we propose an experimentally feasible electronic mach zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions.   we find two broad spin filtering regimes, one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non - abelian nature of spin rotations, and the other, where one needs a tilted preferential axis to observe the polarized output spinor.   both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. a full account of beam splitter and mirror effects on spin renders solutions only on the tilted basis, but encompasses a broad range of filtering conditions.
reference systems and frames are crucial for high precision _ absolute _ astrometric work, and their foundations must be well - defined. the current frame, the international celestial reference frame, will be discussed : its history, the use of the group delay as the measured quantity, the positional accuracy of 0.3 mas, and possible future improvements. on the other hand, for the determination of the motion of celestial objects,   accuracies approaching 0.01 mas can be obtained by measuring the differential position between the target object and nearby stationary sources.   this _ relative _ astrometric technique uses phase referencing, and the current techniques and limitations are discussed, using the results from four experiments.   brief comments are included on the interpretation of the jupiter gravity deflection experiment of september 2002.
tunneling of atoms between two trapped bose - condensed gases at finite temperatures is explored using a many - body linear response tunneling formalism similar to that used in superconductors.   to lowest order, the tunneling currents can be expressed quite generally in terms of the single - particle green s functions of the isolated bose gases.   a coherent first - order tunneling josephson current between two atomic bose - condensates is found, in addition to coherent and dissipative contributions from second - order condensate - noncondensate and noncondensate - noncondensate tunneling. our work is a generalization of meier and zwerger, who recently treated tunneling between uniform atomic bose gases.   we apply our formalism to the analysis of an out - coupling experiment induced by light wave fields, using a simple bogoliubov - popov quasiparticle approximation for the trapped bose gas. for tunneling into the vacuum  , we recover the results of japha, choi, burnett and band, who recently pointed out the usefulness of studying the spectrum of out - coupled atoms.   in particular, we show that the small tunneling current of noncondensate atoms from a trapped bose gas has a broad spectrum of energies, with a characteristic structure associated with the bogoliubov quasiparticle @xmath0 and @xmath1 amplitudes.
confluent with the single dimension of time, breach of time - reversal symmetry is usually perceived as a one - dimensional concept. in its ultimate realization  the one - way guiding device   it allows optical propagation in one direction, say @xmath0, and forbids it in the opposite direction, @xmath1.   hence, in studies of time - reversal asymmetry the mapping @xmath2 is naturally associated with @xmath3. however, strongly non - reciprocal or one - way nano - scale threads can be used _ to weave meta - surfaces _ thus adding dimensions to this concept. in this new family of surfaces the aforementioned association   _ can not be made_. an example of appropriate threads are the planar one - way particle chains based on the two - type rotation principle.   the resulting surfaces  the meta - weaves   posses generalized non - reciprocity such as `` sector - way '' propagation, and offer new possibilities for controlling light in thin surfaces.   we study several meta - weave designs and their asymmetries in the wave - vector space.   .
we calculate the elastic field mediated interaction between macroscopic particles in a columnar hexagonal phase.   the interaction is found to be long - ranged and non - central, with both attractive and repulsive parts.   we show how the interaction modifies the particle correlations and the column fluctuations.   we also calculate the interaction of particles with the topological defects of the columnar phase.   the particle - defect interaction reduces the mobility of the defects.
we suggest that the hysteretic cycle of black hole state transitions arises from two established properties of accretion disks : the increase in turbulent stress in disks threaded by a net magnetic field and the ability of thick ( but not thin ) disks to advect such a field radially. during quiescence,   magnetic field loops are generated by the magnetorotational instability at the interface between the inner hot flow and outer thin disk.   vertical flux is advected into and accumulates stochastically within the inner flow, where it stimulates the turbulence so that @xmath0.   the transition to a geometrically thin inner disk occurs when @xmath1, and the first  thin " disk to form is itself moderately thick, strongly magnetized, and able to advect field inward.   these properties favor episodic jet production.   as the accretion rate declines magnetic flux escapes, @xmath2 decreases to @xmath3, and a hot inner flow is not re - established until @xmath4.   we discuss possible observational consequences of our scenario.
we consider a classical, two  dimensional system of identical particles which interact _ via _ a finite  ranged, repulsive pair potential.   we assume that the system is in a crystalline phase.   we calculate the normal vibrational modes of a two  dimensional square bravais lattice, first analytically within the nearest  neighbour approximation, and then numerically, relaxing the preceding hypothesis.   we show that, in the harmonic approximation, the excitation of a transverse vibrational mode leads to the breakdown of the square lattice.   we next study the case of the hexagonal bravais lattice and we show that it can be stable with respect to lattice vibrations.   we give a criterion determining whether or not it is stable in the nearest   neighbour approximation.   finally, we apply our results to a two  dimensional system of composite bosons and infer that the crystalline phase of such a system, if it exists, corresponds to a hexagonal lattice.
noncontiguous transmission schemes combined with high power - efficiency requirements pose big challenges for radio transmitter and power amplifier ( pa ) design and implementation. due to the nonlinear nature of the pa,   severe unwanted emissions can occur, which can potentially interfere with neighboring channel signals or even desensitize the own receiver in frequency division duplexing ( fdd ) transceivers. in this article, to suppress such unwanted emissions, a low - complexity sub - band dpd solution, specifically tailored for spectrally noncontiguous transmission schemes in low - cost devices, is proposed.   the proposed technique aims at mitigating only the selected spurious intermodulation distortion components at the pa output, hence allowing for substantially reduced processing complexity compared to classical linearization solutions.   furthermore, novel decorrelation based parameter learning solutions are also proposed and formulated, which offer reduced computing complexity in parameter estimation as well as the ability to track time - varying features adaptively.   comprehensive simulation and rf measurement results are provided, using a commercial lte - advanced mobile pa, to evaluate and validate the effectiveness of the proposed solution in real world scenarios.   the obtained results demonstrate that highly efficient spurious component suppression can be obtained using the proposed solutions.   adaptive filters, carrier aggregation, digital predistortion, frequency division duplexing, nonlinear distortion, power amplifier, software defined radio, spectrally agile radio, spurious emission, 3gpp lte - advanced.
we consider dust formation during the ejection of the hydrogen envelope of a red supergiant during a failed supernova ( sn ) creating a black hole. while the dense, slow moving ejecta are very efficient at forming dust, only the very last phases of the predicted visual transient will be obscured.   the net grain production consists of @xmath0 of very large grains ( @xmath1 to @xmath2 m ).   this means that failed sne could be the source of the very large extrasolar dust grains identified by _   ulysses _, _ galileo _ and radar studies of meteoroid re - entry trails rather than their coming from an ejection process associated with protoplanetary or other disks.   stars : supernovae : general : dust : black holes
hydrogen adatoms are one of the most the promising proposals for the functionalization of graphene.   hydrogen induces narrow resonances near the dirac energy, which lead to the formation of magnetic moments.   furthermore, they also create local lattice distortions which enhance the spin - orbit coupling.   the combination of magnetism and spin - orbit coupling allows for a rich variety of phases, some of which have non trivial topological features.   we analyze the interplay between magnetism and spin - orbit coupling in ordered arrays of hydrogen on graphene monolayers, and classify the different phases that may arise.   we extend our model to consider arrays of adsorbates in graphene - like crystals with stronger intrinsic spin - orbit couplings.
a great variety of experiments, like heat release measurements, acoustic measurements, and transport measurements on mesoscopic samples have proved that two level systems ( tlss ) have a crucial role in the low temperature thermal and electric properties of disordered systems.   this paper is aimed at reviewing the role of slow tlss in point contacts.   first the theory of point contacts is summarized, concentrating on the discussion of different point contact models, and on the different regimes of electron flow in the contact, mainly focusing on the ballistic and diffusive limit.   the boltzmann equation is solved in both regimes, and the position dependence of the electrical potential is determined.   then the scattering processes in point contacts are investigated, particularly concentrating on the scattering on slow tlss.   if the the electron assisted transitions between the two states are negligible the electron - two level system interaction can be treated with a simplified hamiltonian.   the scattering on such slow tlss causes nonlinearity in the current - voltage characteristics of the point contact, which can be determined using fermi s golden role.   these calculations are presented showing both the contribution of elastic and inelastic scattering, and including the dependence on the position of the tls, and on the effect of high frequency irradiation.   these results are used to discuss the differences between these slow tlss and the fast centers which may be described by the two channel kondo model.   the available experimental results are analyzed, distinguishing between the effects due to the different types of tlss.
open neutrino physics issues require precision studies, both theoretical and experimental ones, and towards this aim coherent neutral current neutrino - nucleus scattering events are expected to be observed soon. in this work, we explore @xmath0-nucleus processes from a nuclear theory point of view and obtain results with high confidence level based on accurate nuclear structure cross sections calculations. besides cross sections,   the present study includes simulated signals expected to be recorded by nuclear detectors, differential event rates as well as total number of events predicted to be measured.   our original cross sections calculations are focused on measurable rates for the standard model process, but we also perform calculations for various channels of the non - standard neutrino - nucleus reactions and come out with promising results within the current upper limits of the corresponding exotic parameters.   we concentrate on the possibility of detecting ( i ) supernova neutrinos by using massive detectors like those of the gerda and supercdms dark matter experiments and ( ii ) laboratory neutrinos produced near the spallation neutron source facilities ( at oak ridge national lab ) by the coherent experiment.   our nuclear calculations take advantage of the relevant experimental sensitivity and employ the severe bounds extracted for the exotic parameters entering the lagrangians of various particle physics models and specifically those resulting from the charged lepton flavour violating @xmath1 experiments ( mu2e and comet experiments ).
we propose an interferometric method to investigate the non - locality of high - dimensional two - photon orbital angular momentum states generated by spontaneous parametric down conversion.   we incorporate two half - integer spiral phase plates and a variable - reflectivity output beam splitter into a mach - zehnder interferometer to build an orbital angular momentum analyzer.   this setup enables testing the non - locality of high - dimensional two - photon states by repeated use of the clauser - horne inequality.
hidden - variable resultant methods are a class of algorithms for solving multidimensional polynomial rootfinding problems. in two dimensions,   when significant care is taken, they are competitive practical rootfinders. however, in higher dimensions they are known to miss zeros, calculate roots to low precision, and introduce spurious solutions.   we show that the hidden variable resultant method based on the cayley ( dixon or bzout ) matrix is inherently and spectacularly numerically unstable by a factor that grows exponentially with the dimension.   we also show that the sylvester matrix for solving bivariate polynomial systems can square the condition number of the problem.   in other words, two popular hidden variable resultant methods are numerically unstable, and this mathematically explains the difficulties that are frequently reported by practitioners.   regardless of how the constructed polynomial eigenvalue problem is solved, severe numerical difficulties will be present. along the way  , we prove that the cayley resultant is a generalization of cramer s rule for solving linear systems and generalize clenshaw s algorithm to an evaluation scheme for polynomials expressed in a degree - graded polynomial basis.   resultants, rootfinding, conditioning, multivariate polynomials, cayley, sylvester    13p15, 65h04, 65f35
the galactic neighborhood, extending from the milky way to redshifts of about 0.1, is our unique local laboratory for detailed study of galaxies and their interplay with the environment.   such study provides a foundation of knowledge for interpreting observations of more distant galaxies and their environment.   the astro 2010 science frontier galactic neighborhood panel identified four key scientific questions : 1 ) what are the flows of matter and energy in the circumgalactic medium?   2 ) what controls the mass - energy - chemical cycles within galaxies?   3 ) what is the fossil record of galaxy assembly from first stars to present?   4 ) what are the connections between dark and luminous matter? these questions, essential to the understanding of galaxies as interconnected complexes, can be addressed most effectively and/or uniquely in the galactic neighborhood.   the panel also highlighted the discovery potential of time - domain astronomy and astrometry with powerful new techniques and facilities to greatly advance our understanding of the precise connections among stars, galaxies, and newly discovered transient events.   the relevant needs for laboratory astrophysics will be emphasized, especially in the context of supporting nasa missions.
the bright gamma - ray quasar 4c + 55.17 is a distant source ( @xmath0 ) with a hard spectrum at gev energies as observed by the large area telescope ( lat ) on board the _ fermi _ satellite.   this source is identified as a good source candidate for very - high - energy ( vhe ; @xmath1 gev ) gamma rays. in general vhe gamma rays from distant sources   provide an unique opportunity to study the extragalactic background light ( ebl ) and underlying astrophysics.   the flux intensity of this source in the vhe range is investigated.   then, constraints on the ebl are derived from the attenuation of gamma - ray photons coming from the distant blazar.   we searched for a gamma - ray signal from this object using the 35-hour observations taken by the magic telescopes between november 2010 and january 2011.   no significant vhe gamma - ray signal was detected.   we computed the upper limits of the integrated gamma - ray flux at 95% confidence level of @xmath2 @xmath3 s@xmath4 and @xmath5 @xmath3 s@xmath4 above @xmath6 gev and @xmath7 gev, respectively.   the differential upper limits in four energy bins in the range from @xmath8 gev to @xmath9 gev are also derived.   the upper limits are consistent with the attenuation predicted by low - flux ebl models on the assumption of a simple power - law spectrum extrapolated from lat data.        galaxies : active  galaxies : nuclei quasars : individual : 4c + 55.17  gamma - rays : galaxies  radiation mechanisms : non - thermal
we present a systematic study of the ballistic electron conductance through @xmath0 and @xmath1 transition metal atoms attached to copper and palladium crystalline electrodes.   we employ the _ ab initio _ screened korringa - kohn - rostoker green s function method to calculate the electronic structure of nanocontacts while the ballistic transmission and conductance eigenchannels were obtained by means of the kubo approach as formulated by baranger and stone.   we demonstrate that the conductance of the systems is mainly determined by the electronic properties of the atom bridging the macroscopic leads.   we classify the conducting eigenchannels according to the atomic orbitals of the contact atom and the irreducible representations of the symmetry point group of the system that leads to the microscopic understanding of the conductance.   we show that if impurity resonances in the density of states of the contact atom appear at the fermi energy, additional channels of appropriate symmetry could open. on the other hand the transmission of the existing channels   could be blocked by impurity scattering.
we use first principles density functional theory to calculate the electronic structure of the phenylthiolate ( s - c@xmath0h@xmath1 ) self - assembled monolayer ( sam ) on cu(111 ) and au(111 ) substrates.   we find significant lateral dispersion of the sam molecular states and discuss its implications for transport properties of the molecular wire array.   we calculate the two photon photoemission spectra and the work function of the sam on cu(111 ) and compare them with the available experimental data.   our results are used to discuss assignments of the observed spectral data and yield predictions for new electronic states due to the monolayer not yet accessed experimentally.
current acceleration of the cosmic expansion leads to coincidence as well as fine - tuning issues in the framework of general relativity.   dynamical scalar fields have been introduced in response of these problems, some of them invoking screening mechanisms for passing local tests of gravity.   recent lab experiments based on atom interferometry in a vacuum chamber have been proposed for testing modified gravity models.   so far only analytical computations have been used to provide forecasts.   we derive numerical solutions for chameleon models that take into account the effect of the vacuum chamber wall and its environment. with this realistic profile of the chameleon field in the chamber, we refine the forecasts that were derived analytically.   we finally highlight specific effects due to the vacuum chamber that are potentially interesting for future experiments.
this paper is concerned with stochastic sir and seir epidemic models on random networks in which individuals may rewire away from infected neighbors at some rate @xmath0 ( and reconnect to non - infectious individuals with probability @xmath1 or else simply drop the edge if @xmath2 ), so - called preventive rewiring.   the models are denoted sir-@xmath0 and seir-@xmath0, and we focus attention on the early stages of an outbreak, where we derive expression for the basic reproduction number @xmath3 and the expected degree of the infectious nodes @xmath4 using two different approximation approaches.   the first approach approximates the early spread of an epidemic by a branching process, whereas the second one uses pair approximation.   the expressions are compared with the corresponding empirical means obtained from stochastic simulations of sir-@xmath0 and seir-@xmath0 epidemics on poisson and scale - free networks. without rewiring of exposed nodes,   the two approaches predict the same epidemic threshold and the same @xmath4 for both types of epidemics, the latter being very close to the mean degree obtained from simulated epidemics over poisson networks. above the epidemic threshold,   pairwise models overestimate the value of @xmath3 computed from simulations, which turns out to be very close to the one predicted by the branching process approximation.   when exposed individuals also rewire with @xmath5 ( perhaps unaware of being infected ), the two approaches give different epidemic thresholds, with the branching process approximation being more in agreement with simulations.   network epidemic models, preventive rewiring, branching process, pair approximation.
our goal is to examine the role of anomalies in the hydrodynamic regime of field theories.   we employ methods based on gauge / gravity duality to examine r - charge anomalies in the hydrodynamic regime of strongly thooft coupled, large @xmath0, @xmath1 super yang - mills.   we use a single particle spectrum treatment based on the familiar  level - crossing " picture of chiral anomalies to investigate thermalized massless qed. in each case   we work in the presence of a homogeneous background magnetic field, and find the same result. regardless of whether a particular current is anomalously non - conserved or not, as long as it participates in an anomalous 3-pt.   correlator, its constitutive relation receives a new term : @xmath2.   this agrees with results found by alekseev et.al. for qed.   we include a general, symmetry based argument for the presence of such terms, and use linear response theory to determine their coefficients in a model with anomalous global charges.   this last method, we apply to briefly examine baryon transport in chiral qcd in a strong magnetic field.
our view of the low - redshift cosmic web has been revolutionized by galaxy redshift surveys such as 6dfgs, sdss and 2mrs.   however, the trade - off between depth and angular coverage limits a systematic three - dimensional account of the entire sky beyond the local volume ( @xmath0 ). in order to reliably map the universe to cosmologically significant depths over the full celestial sphere  , one must draw on multiwavelength datasets and state - of - the - art photometric redshift techniques.   we have undertaken a dedicated program of cross - matching the largest photometric all - sky surveys  2mass,   wise and supercosmos  to obtain accurate redshift estimates of millions of galaxies.   the first outcome of these efforts  the 2mass photometric redshift catalog ( 2mpz, ( *???   * bilicki  2014a ) )  has been publicly released and includes almost 1  million galaxies with a mean redshift of @xmath1. here   we summarize how this catalog was constructed and how using the wise mid - infrared sample together with supercosmos optical data allows us to push to redshift shells of @xmath2@xmath3 on unprecedented angular scales.   our catalogs, with @xmath4 million sources in total, provide access to cosmological volumes crucial for studies of local galaxy flows ( clustering dipole, bulk flow ) and cross - correlations with the cosmic microwave background such as the integrated sachs - wolfe effect or lensing studies.
we have obtained deep near - infrared @xmath0-band william herschel telescope observations of a sample of 15 nearby spiral galaxies having a range of hubble types and apparent bar strengths.   the near - infrared light distributions are converted into gravitational potentials, and the maximum relative gravitational torques due to the bars and the spirals are estimated.   we find that spiral strength, @xmath1, and bar strength, @xmath2, correlate well with other measures of spiral arm and bar amplitudes, and that spiral and bar strengths also correlate well with each other.   we also find a correlation between the position angle of the end of the bar and the position angle of the inner spiral.   these correlations suggest that the bars and spirals grow together with the same rates and pattern speeds.   we also show that the strongest bars tend to have the most open spiral patterns. because open spirals imply high disk - to - halo mass ratios, bars and spirals most likely grow together as a combined disk instability.   they stop growing for different reasons, however, giving the observed variation in bar - spiral morphologies.   bar growth stops because of saturation when most of the inner disk is in the bar, and spiral growth stops because of increased stability as the gas leaves and the outer disk heats up.
we re - examine the historically important decay of the neutral pion into two photons.   schwinger s equivalence theorem is confirmed.   we then consider radiative corrections to the famous adler - bell - jackiw ( abj ) anomaly.   the result depends crucially on a physically motivated regularization scheme.   our approach is largely based on schwinger s source ( dispersion ) method.   plus2pt minus4pt plus2pt minus4pt plus2pt minus4pt plus2pt minus4pt
the red - sequence cluster survey ( rcs ) provides a large and deep photometric catalog of galaxies in the @xmath0 and @xmath1 bands for  90 square degrees of sky, and supplemental @xmath2 and @xmath3 data have been obtained for 33.6 deg@xmath4.   we compile a photometric redshift catalog from these 4-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with cnoc2 and goods / hdf - n redshift data.   the training set includes 4924 spectral redshifts.   the resulting catalog contains more than one million galaxies with photometric redshifts @xmath5 and @xmath6, giving an rms scatter @xmath7 within the redshift range @xmath8 and @xmath9 for galaxies at @xmath10.   we describe the empirical quadratic polynomial photometric redshift fitting technique which we use to determine the relation between redshift and photometry.   a kd - tree algorithm is used to divide up our sample to improve the accuracy of our catalog.   we also present a method for estimating the photometric redshift error for individual galaxies.   we show that the redshift distribution of our sample is in excellent agreement with smaller and much deeper photometric and spectroscopic redshift surveys.
radio recombination lines at @xmath0 cm reveals the presence of an extended component of ionized gas of lower density ( @xmath1 100 3 ) in the sgr  a complex.   this component extends well beyond the thermal ` mini - spiral'sgra - west which seem to be embedded in it.   the low - density component is present over the entire extent of sgra east and possibly beyond and it is responsible for the turnover in the spectrum of sgra east and the halo observed by pedlar et al ( 1989 ) at @xmath2 = 90 cm. the radial velocity of the extended ionized gas range from + 50 to 200 with minima of emission near 50 and 150.   the total mass of the low - density component is estimated to be @xmath3 m@xmath4.   a possible extended feature at a high velocity of 470 is also detected, but needs further observations to confirm it.
we consider a modified ricci flow equation whose stationary solutions include einstein and ricci soliton metrics, and we study the linear stability of those solutions relative to the flow. after deriving various criteria that imply linear stability, we turn our attention to left - invariant soliton metrics on ( non - compact ) simply connected solvable lie groups and prove linear stability of many such metrics.   these include an open set of two - step solvsolitons, all two - step nilsolitons, two infinite families of three - step solvable einstein metrics, all nilsolitons of dimensions six or less, and all solvable einstein metrics of dimension seven or less with codimension - one nilradical. for each linearly stable metric  , dynamical stability follows from a generalization of the techniques of guenther, isenberg, and knopf.
new results of a search for the ultra - rare decay @xmath0 by the meg collaboration are reported in this contribution.   the data were taken during 2009 and correspond to approximately 6.5 10@xmath1 muon stopped on target.   a maximum likelihood analysis sets an upper limit at 90% c.l. on the branching ratio, bf(@xmath0 )   @xmath21.5 10@xmath3.   the results presented here are preliminary.
in this paper a family of fixed point algorithms, generalizing the petviashvili method, is considered.   a previous work studied the convergence of the methods.   presented here is a second part of the analysis, concerning the introduction of some acceleration techniques into the iterative procedures.   the purpose of the research is two - fold : one is improving the performance of the methods in case of convergence and the second one is widening their application when generating traveling waves in nonlinear dispersive wave equations, transforming some divergent into convergent cases.   two families of acceleration techniques are considered : the vector extrapolation methods and the anderson acceleration methods.   a comparative study through several numerical experiments is carried out.   petviashvili type methods, traveling wave generation, iterative methods for nonlinear systems, orbital convergence, acceleration techniques, vector extrapolation methods, anderson acceleration    msc2010 : 65h10, 65m99, 35c99, 35c07, 76b25
we outline here the next generation of cluster  finding algorithms.   we show how advances in computer science and statistics have helped develop robust, fast algorithms for finding clusters of galaxies in large multi   dimensional astronomical databases like the sloan digital sky survey ( sdss ).   specifically, this paper presents four new advances : ( 1 ) a new semi - parametric algorithm  nicknamed `` c4 ''  for jointly finding clusters of galaxies in the sdss and rosat all  sky survey databases ; ( 2 ) the introduction of the _ false discovery rate _ into astronomy ; ( 3 ) the role of kernel shape in optimizing cluster detection ; ( 4 ) a new determination of the x  ray cluster luminosity function which has bearing on the existence of a `` deficit '' of high redshift, high luminosity clusters.   this research is part of our `` computational astrostatistics '' collaboration ( see nichol et al  . 2000 ) and the algorithms and techniques discussed herein will form part of the `` virtual observatory '' analysis toolkit.
thermodynamic properties of an ultracold fermi gas in a harmonic trap are calculated within a local density approximation, using a conserving many - body formalism for the bcs to bec crossover problem, which has been developed by haussmann _   et al. _   [ phys.   rev.   a * 75 *, 023610 ( 2007 ) ].   we focus on the unitary regime near a feshbach resonance and determine the local density and entropy profiles and the global entropy @xmath0 as a function of the total energy @xmath1.   our results are in good agreement with both experimental data and previous analytical and numerical results for the thermodynamics of the unitary fermi gas.   the value of the bertsch parameter at @xmath2 and the superfluid transition temperature, however, differ appreciably.   we show that, well in the superfluid regime, removal of atoms near the cloud edge enables cooling far below temperatures that have been reached so far.
three elastic phases of covalent networks, ( i ) floppy, ( ii ) isostatically rigid and ( iii ) stressed - rigid have now been identified in glasses at specific degrees of cross - linking ( or chemical composition ) both in theory and experiments.   here we use size - increasing cluster combinatorics and constraint counting algorithms to study analytically possible consequences of self - organization. in the presence of small rings that can be locally i, ii or iii, we obtain two transitions instead of the previously reported single percolative transition at the mean coordination number @xmath0, one from a floppy to an isostatic rigid phase, and a second one from an isostatic to a stressed rigid phase.   the width of the intermediate phase @xmath1 and the order of the phase transitions depend on the nature of medium range order ( relative ring fractions ).   we compare the results to the group iv chalcogenides, such as ge - se and si - se, for which evidence of an intermediate phase has been obtained, and for which estimates of ring fractions can be made from structures of high t crystalline phases.   pacs : 61.20n-81.20p
calculations are carried out for the scattering of heavy rare gas atoms with surfaces using a recently developed classical theory that can track particles trapped in the physisorption potential well and follow them until ultimate desorption.   comparisons are made with recent experimental data for xenon scattering from molten gallium and indium, systems for which the rare gas is heavier than the surface atoms.   the good agreement with the data obtained for both time - of - flight energy - resolved spectra and for total scattered angular distributions yields an estimate of the physisorption well depths for the two systems.
the track timing capabilities of a silicon drift detector based tracker for a future linear electron - positron collider are evaluated.   we show such a detector can time tracks at the nanosecond, and for high-@xmath0, sub - nanosecond level.   this implies that, even for collider designs with the bunch spacing at 1.4  @xmath1, every track can be assigned to a particular bunch crossing at a confidence level of up to two standard deviations.   we suggest a choice for the drift axes in the tracker layers to simultaneously optimize the momentum resolution and track timing.   wsu - hep-0206   ,   ,    @xmath2 linear collider ; nlc ; jlc ; tesla ; tracking ; silicon drift detector ; pile - up ; timing.   _ pacs _ : 29.40.vj ; 29.20.dh
this paper gives a short and historical survey on the theory of pure motives in algebraic geometry and reviews some of the recent developments of this theory in noncommutative geometry.   the second part of the paper outlines the new theory of endomotives and some of its relevant applications in number - theory.
we report a comprehensive analysis of the ground state properties of axisymmetric toroidal crystals based on the elastic theory of defects on curved substrates.   the ground state is analyzed as a function of the aspect ratio of the torus, which provides a non - local measure of the underlying gaussian curvature, and the ratio of the defect core - energy to the young modulus.   several structural features are discussed, including a spectacular example of curvature - driven amorphization in the limit of the aspect ratio approaching one.   the outcome of the elastic theory is then compared with the results of a numerical study of a system of point - like particles constrained on the surface of a torus and interacting via a short range potential.
we report the discovery and confirmation of eight new two - image lensed quasars by the sloan digital sky survey ( sdss ) quasar lens search.   the lenses are sdss  j0904 + 1512 ( image separation @xmath0, source redshift @xmath1 ), sdss  j1054 + 2733 ( @xmath2, @xmath3 ), sdss  j1055 + 4628 ( @xmath4, @xmath5 ), sdss  j1131 + 1915 ( @xmath6, @xmath7 ), sdss  j1304 + 2001 ( @xmath8, @xmath9 ), sdss  j1349 + 1227 ( @xmath10, @xmath11 ), sdss  j1455 + 1447 ( @xmath12, @xmath13 ), and sdss  j1620 + 1203 ( @xmath14, @xmath15 ).   three of them, sdss  j1055 + 4628, sdss  j1455 + 1447, and sdss  j1620 + 1203, satisfy the criteria for constructing our statistical sample for studying the cosmological model.   based on galactic absorption lines of the lens galaxies, we also derive lens redshifts of @xmath16 and @xmath17 for sdss  j1620 + 1203 and the previously discovered lens sdss  j0746 + 4403, respectively.
we experimentally demonstrate the entanglement can be created on two distant particles using separate state.   we show that two data particles can share some entanglement while one ancilla particle always remains separable from them during the experimental evolution of the system.   our experiment can be viewed as a benchmark to illustrate the idea that no prior entanglement is necessary to create entanglement.
we extend the balancing domain decomposition by constraints ( bddc ) method to flows in porous media discretised by mixed - hybrid finite elements with combined mesh dimensions.   such discretisations appear when major geological fractures are modelled by 1d or 2d elements inside three - dimensional domains. in this set - up, the global problem as well as the substructure problems have a symmetric saddle - point structure, containing a ` penalty'block due to the combination of meshes.   we show that the problem can be reduced by means of iterative substructuring to an interface problem, which is symmetric and positive definite  . the interface problem can thus be solved by conjugate gradients with the bddc method as a preconditioner.   a  parallel implementation of this algorithm is incorporated into an existing software package for subsurface flow simulations.   we study the performance of the iterative solver on several academic and real - world problems.   numerical experiments illustrate its efficiency and scalability.
we propose to use the large - scale structure of the universe as a cosmic standard ruler, based on the fact that the pattern of galaxy distribution should be maintained in the course of time on large scales. by examining the scale - dependence of the pattern in different redshift intervals it is possible to reconstruct the expansion history of the universe, and thus to measure the cosmological parameters governing the expansion of the universe.   the features in the galaxy distribution that can be used as standard rulers include the topology of large - scale structure and the overall shapes of galaxy power spectrum and correlation function.   the genus, being an intrinsic topology measure, is resistant against the non - linear gravitational evolution, galaxy biasing, and redshift - space distortion effects, and thus is ideal for quantifying the primordial topology of the large - scale structure.   the expansion history of the universe can be constrained by comparing among the genus measured at different redshifts. in the case of initially gaussian fluctuations   the genus accurately recovers the slope of the primordial power spectrum near the smoothing scale, and the expansion history can be constrained by comparing between the predicted and measured genus.
we have used deep high - resolution hubble space telescope acs observations to image the cluster ngc 1978 in the large magellanic cloud.   this high - quality photometric data set allowed us to confirm the high ellipticity ( @xmath00.30@xmath10.02 ) of this stellar system.   the derived color magnitude diagram allowed a detailed study of the main evolutionary sequences : in particular we have detected the so called bump along the red giant branch ( at @xmath2=19.10@xmath10.10 ).   this is the first detection of this feature in an intermediate - age cluster.   + moreover the morphology of the evolutionary sequence and their population ratios have been compared with the expectations of different theoretical models ( namely basti, pel and padua ) in order to quantify the effect of convective overshooting.   the best agreement ( both in terms of morphology and star counts ) has been found the pel ( _ pisa evolutionary library _ ) isochrone with z=0.008 ( consistenly with the most recent determination of the cluster metallicity, =-0.37 dex ) and a mild overshooting efficiency ( @xmath3=0.1 ). by adopting this theoretical set an age of @xmath4=1.9@xmath10.1 gyr has been obtained.
we investigated the time lags and the evolution of the cross spectra of z source gx  5 - 1, observed by the rossi x - ray timing explorer ( rxte ), when it is in the horizontal branch oscillations.   we showed that the time lags of 3 horizontal branch oscillations are related to the position on the hardness intensity diagram.   all of the three qpos were shown to have hard time lags.   however on the cross spectra, one is in a ` dip ', one in a ` bump ', the other has no so obvious characteristic.   the time lags of two of the qpos decrease with qpo s frequency, while the other has a trend increasing with its frequency.   moreover, in the normal branch, we found no significant time lags in the present observational data.
we study coarse - grained ( group - level ) alignment dynamics of individual - based animal group models for _ heterogeneous _ populations consisting of informed ( on preferred directions ) and uninformed individuals.   the orientation of each individual is characterized by an angle, whose dynamics are nonlinearly coupled with those of all the other individuals, with an explicit dependence on the difference between the individual s orientation and the instantaneous average direction.   choosing convenient coarse - grained variables ( suggested by uncertainty quantification methods ) that account for rapidly developing correlations during initial transients, we perform efficient computations of coarse - grained steady states and their bifurcation analysis. we circumvent the derivation of coarse - grained governing equations, following an equation - free computational approach.
we present calculated spectral properties and lattice parameters for cerium pnictides ( cen, cep, ceas, cesb, cebi ) and @xmath0-ce, within the lda / gga+dmft ( local density approximation / generalized gradient approximation + dynamical mean field theory ) approach.   the effective impurity model arising in the dmft is solved by using the spin - polarized t - matrix fluctuation - exchange ( sptf ) solver for cen compound, and the hubbard  i ( hi ) solver for cep, ceas, cesb, and cebi.   for all the addressed compounds the calculated spectral properties are in reasonable agreement with measured photoelectron spectra at high binding energies. at low binding energies   the hi approximation does not manage to capture the kondo - like peak observed for several of the ce - pnictides.   nevertheless, the calculated lattice constants are in a good agreement with available experimental data, showing that the such a peak does not play a major role on the bonding properties.   furthermore, the hi calculations are compared to a simpler treatment of the ce @xmath1 electron as core - like in lda / gga for cep, ceas, cesb, and cebi, and the two approaches are found to give similar results.
a century of coherent experimental and theoretical investigations have uncovered the laws of nature that underly nuclear physics.   the standard model of strong and electroweak interactions, with its modest number of input parameters, dictates the dynamics of the quarks and gluons - the underlying building blocks of protons, neutrons, and nuclei.   while the analytic techniques of quantum field theory have played a key role in understanding the dynamics of matter in high energy processes, they encounter difficulties when applied to low - energy nuclear structure and reactions, and dense systems.   expected increases in computational resources into the exa - scale during the next decade will provide the ability to numerically compute a range of important strong interaction processes directly from qcd with quantifiable uncertainties using the technique of lattice qcd.   these calculations will refine the chiral nuclear forces that are used as input into nuclear many - body calculations, including the three- and four - nucleon interactions.   i discuss the state - of - the - art lattice qcd calculations of quantities of interest in nuclear physics, progress that is expected in the near future, and the impact upon nuclear physics.   + * keywords : * _ nuclear forces ; lattice qcd _    * *    nuclear forces from lattice quantum chromodynamics      +    @xmath0__institute for nuclear theory, box 351550, seattle, wa 98195 - 1550, usa _   _ +
we present a study of the effects of the tensor - isospin term of the effective interaction in hartree - fock and random phase approximation calculations.   we used finite - range forces of gogny type, and we added to them a tensor - isospin term which behaves, at large internucleonic distances, as the analogous term of the microscopic interactions.   the strength of this tensor force has been chosen to reproduce the experimental energy of the lowest 0@xmath0 excited state in @xmath1o, which shows large sensitivity to this term of the interaction. with these finite - range interactions  , we have studied the effects of the tensor - isospin force in ground and excited states of carbon, oxygen, calcium, nickel, zirconium, tin and lead isotopes.   our results show that the tensor force affects mainly the nucleon single particle energies. however, we found some interesting cases where also bulk nuclear properties are sensitive to the tensor interaction.
the supersymmetric extension of the standard model with an additional gauge singlet is analysed in detail in the light of the recent experimental bounds on supersymmetric particles.   the useful part of the parameter space and the particle spectrum are displayed.   we find that once the recent bounds on the chargino mass are imposed, all other new particles practically satisfy the present experimental limits. special attention is given to particles to be searched for in the future experiments.   the singlet fields tend to decouple and give rise to an effective mssm, enlarging the validity of many phenomenological analyses based in the minimal field content.   however, in some ranges of the parameters the singlino is the lightest neutralino, which modifies the signature for susy particles.   simple analytical approximations are developed that qualitatively explain the numerical results.   orsay lpthe-96 - 85   + saclay spht - t96/050 + strasbourg lpt-96 - 21 +   .5 cm    1.5 cm    * u.  ellwanger *    lpthe, universit de paris - sud, f-91400 orsay    * m.  rausch de traubenberg *    laboratoire de physique thorique, universit louis pasteur,    strasbourg    * c.a.   savoy *    service de physique thorique, c. e. de saclay, f-91191 gif - sur - yvette
a general constructive procedure is presented for analyzing magnetic instabilities in two - dimensional materials, in terms of  double nesting, and applied to hartree - fock hf+rpa and gutzwiller approximation ga+rpa calculations of the hubbard model.   applied to the cuprates, it is found that competing magnetic interactions are present only for hole doping, between half filling and the van hove singularity.   while hf+rpa instabilities are present at all dopings ( for sufficiently large hubbard @xmath0 ), in a gutzwiller approximation they are restricted to a doping range close to the range of relevance for the physical cuprates.   the same model would hold for charge instabilities, except that the interaction is more likely to be @xmath1-dependent.
we elaborate on several observable consequences of the quantum - critical - point scenario.   in particular we show that the strong k - dependent scattering of the quasiparticles with the quasi - critical charge and spin fluctuations reproduces the main features of the low - energy spectral weights and of the observed fermi surfaces. in the underdoped   cuprates the attractive k - dependent charge scattering drives the formation of the pseudogap at the m points below the crossover temperature @xmath0. in this context   we discuss models for pseudogap formation with relevant scattering in the particle - particle and particle - hole channels.   the experimental consequences for the pair - fluctuation and for the pseudogap behavior are investigated.
irradiation with high energy photons ( 10.2 @xmath0 11.8 ev ) was applied to small diamondoids isolated in solid rare gas matrices at low temperature.   the photoproducts were traced via uv absorption spectroscopy.   we found that upon ionization the smallest of these species lose a peripheral h atom to form a stable closed - shell cation.   this process is also likely to occur under astrophysical conditions for gas phase diamondoids and it opens the possibility to detect diamond - like molecules using their rotational spectrum since the dehydrogenated cations possess strong permanent dipole moments.   the lowest - energy electronic features of these species in the uv were found to be rather broad, shifting to longer wavelengths with increasing molecular size.   calculations using time - dependent density functional theory support our experimental findings and extend the absorption curves further into the vacuum ultraviolet.   the complete @xmath1 spectrum displays surprisingly strong similarities to meteoritic nanodiamonds containing 50 times more c atoms.
this note reexamines the data from a weight - judging competition described in an article by francis galton published in 1907. following the correction of some errors,   it is shown that this forecasting competition is an interesting precursor of two more recent developments in the statistical forecasting literature.   one is forecast combination, with the mean forecast here exactly coinciding with the outcome, and the second is the use of two - piece frequency and probability distributions to describe asymmetry.
we present an exhaustive analysis of transport measurements performed in _ twinned _ yba@xmath0cu@xmath1o@xmath2 single crystals which stablishes that the vortex solid - liquid transition is first order when the magnetic field @xmath3 is applied at an angle @xmath4 away from the direction of the twin planes.   we show that the resistive transitions are _ hysteretic _ and the v - i curves are non - linear, displaying a characteristic s - shape at the melting line @xmath5, which scales as @xmath6.   these features are gradually lost when the critical point @xmath7 is approached. above @xmath7   the v - i characteristics show a linear response in the experimentally accessible v - i window, and the transition becomes reversible.   finally we show that the first order phase transition takes place between a highly correlated vortex liquid in the field direction and a solid state of unknown symmetry. as a consequence,   the available data support the scenario for a _ vortex - line melting _ rather than a _   vortex sublimation _ as recently suggested [ t.sasagawa et al.   prl 80, 4297 ( 1998 ) ].
we report on time - resolved photometric observations of the wz sge - type dwarf nova, eg cnc ( huruhata s variable ), during its superoutburst in 19961997.   eg cnc, after the main superoutburst accompanied with development of superhumps typical of a wz sge - type dwarf nova, exhibited a series of six major rebrightenings. during these rebrightenings and   the following long fading tail, eg cnc persistently showed superhumps having a period equal to the superhump period observed during the main superoutburst.   the persistent superhumps had a constant superhump flux with respect to the rebrightening phase.   these findings suggest the superhumps observed during the rebrightening stage and the fading tail are a  remnant " of usual superhumps, and are not newly triggered by rebrightenings. by comparison with the 1977 outburst of this object and outbursts of other wz sge - type dwarf novae  , we propose an activity sequence of wz sge - type superoutbursts, in which the current outburst of eg cnc is placed between a single - rebrightening event and distinct outbursts separated by a dip.   the post - superoutburst behavior of wz sge - type dwarf novae can be understood in the presence of considerable amount of remnant matter behind the cooling front in the outer accretion disk, even after the main superoutburst.   we consider the premature quenching of the hot state due to the weak tidal effect under the extreme mass ratio of the wz sge - type binary is responsible for the origin of the remnant mass.
we show that, under rather general assumptions, the phase diagram of a quasi - one - dimensional repulsive fermi system consists of two ordered phases : the density wave, spin or charge, and the superconductivity.   it is demonstrated that the symmetry of the superconducting order parameter is a non - universal property sensitive to microscopic details of the model.   three potentially stable superconducting states are identified : they are triplet @xmath0-wave, singlet @xmath1-wave, and @xmath2-wave. presence of multiple competing superconducting states implies that for a real material this symmetry is difficult to predict theoretically and hard to probe experimentally, since artifacts of theoretical approximations or variations in experimental conditions could tip the balance between the superconducting phases.
we present the techniques and early results of our program to measure the luminosity function for white dwarfs in the supercosmos sky survey.   our survey covers over three quarters of the sky to a mean depth of @xmath0, and finds @xmath1 galactic disk wd candidates on applying a conservative lower tangential velocity cut of @xmath2kms@xmath3.   novel techniques introduced in this survey include allowing the lower proper motion limit to vary according to apparent magnitude, fully exploiting the accuracy of proper motion measurements to increase the sample size.   our luminosity function shows good agreement with that measured in similar works.   we find a pronounced drop in the local number density of wds at a @xmath4, and an inflexion in the luminosity function at @xmath5.
we use 62,185 quasars from the sloan digital sky survey dr5 sample to explore the quasar mass - luminosity plane view of virial mass estimation.   previous work shows deviations of @xmath0  dex between virial and reverberation masses.   the decline in quasar number density for the highest - eddington ratio quasars at each redshift provides an upper bound of between @xmath1 and @xmath2 dex for virial mass estimates. across different redshift bins, the maximum possible mgii mass uncertainties average @xmath3 dex, while h@xmath4 uncertainties average @xmath5 dex and civ uncertainties average @xmath6 dex.   any physical spread near the high - eddington - ratio boundary will produce a more restrictive bound.   a comparison of the sub - eddington boundary slope using h@xmath4 and mgii masses finds better agreement with uncorrected mgii masses than with recently proposed corrections.   the best agreement for these bright objects is produced by a multiplicative correction by a factor of 1.19, smaller than the factor of 1.8 previously reported as producing the best agreement for the entire sdss sample.       black hole physics  galaxies : evolution  galaxies : nuclei  quasars : general  accretion, accretion discs
we consider mass - conserving self - similar solutions for smoluchowski s coagulation equation with kernel @xmath0 with @xmath1.   it is known that such self - similar solutions @xmath2 satisfy that @xmath3 is bounded above and below as @xmath4. in this paper we describe in detail via formal asymptotics the qualitative behavior of a suitably rescaled function @xmath5 in the limit @xmath6.   it turns out that @xmath7 as @xmath4.   as @xmath8 becomes larger @xmath9 develops peaks of height @xmath10 that are separated by large regions where @xmath9 is small.   finally, @xmath9 converges to zero exponentially fast as @xmath11.   our analysis is based on different approximations of a nonlocal operator, that reduces the original equation in certain regimes to a system of ode.
several different approximations and techniques have been developed for the calculation of atomic structure, ionization, and excitation of atoms and ions.   these techniques have been used to compute large amounts of spectroscopic data of various levels of accuracy.   this paper presents a review of these theoretical methods to help non - experts in atomic physics to better understand the qualities and limitations of various data sources and assess how reliable are spectral models based on those data.
we investigate energy transfer by the radiation from a cavity qed system in the context of quantum thermodynamics. we propose a method of decomposing it into work and heat within the framework of quantum master equations.   we find that the work and heat respectively correspond to the coherent and incoherent parts of the radiation. in the derivation of the method, it is crucial to investigate the dynamics of the system which receives the radiation from the cavity.
the onset of gaseous inflows and central activity in interacting galaxies is driven largely by induced bars in the host galaxies.   the stability of galaxies against growing bar modes is a direct function of their structural properties  galaxies with central bulges or low disk surface densities are more stable against central starbursts than are bulgeless or disk - dominated systems.   low surface brightness galaxies prove less prone to bar formation and central starbursts than do normal high surface brightness galaxies.   this stability of lsb disks also resolves many of the dynamical pitfalls encountered when attempting to link poststarburst `` e+a '' galaxies to interactions involving normal high surface brightness galaxy progenitors.
breakup of water jets under gravity is a common - place phenomenon.   the role of surface tension in the instability of water jets was recognized by rayleigh and the theory propounded goes by the name of plateau - rayleigh theory.   the necks and bulges down along the jet - length that are created by perturbation waves of wavelengths larger than a certain value keep growing with time and ultimately cause the jet to breakup into drops.   the effect of perturbation waves have been investigated experimentally and found to confirm the essentials of the theory. however, there is no unanimity about the origin of these perturbation waves.   recently, the idea of recoil capillary waves as an important source of the perturbation waves has been emphasized.   the recoil of the end point of the remaining continuous jet at its breakup point is considered to travel upward as a recoil capillary wave which gets reflected at the mouth of the nozzle from which the jet originates.   the reflected capillary wave travels along the jet downward with its doppler shifted wavelength as a perturbation wave.   we set up an experiment to directly verify the existence and effect of the recoil capillary waves and present some preliminary results of our experiment.
the recently updated data of the twin kilohertz quasi - periodic oscillations ( khz qpos ) in the neutron star low - mass x - ray binaries are analyzed.   the power - law fitting @xmath0 and linear fitting @xmath1 are applied, individually, to the data points of four z sources ( gx 17 + 2, gx 340 + 0, gx 5 - 1 and sco x-1 ) and four atoll sources ( 4u 0614 + 09, 4u 1608 - 52, 4u 1636 - 53 and 4u 1728 - 34 ).   the @xmath2-tests show that the power - law correlation and linear correlation both can fit data well.   moreover, the comparisons between the data and the theoretical models for khz qpos are discussed.   qpos ; accretion disks ; neutron stars ; x - rays binaries.
in order to get an estimate of the homogeneity of the distribution of matter in a fast hadron or nucleus, we compute the correlations of the saturation scales @xmath0 between different points in impact - parameter space, in some specific saturation models.   we find that these correlations are quite strong : the saturation scale is nearly uniform in domains whose sizes scale like @xmath1/q_s$ ], which means that the density of gluons should not fluctuate significantly over regions of that typical size.   we expect these conclusions as well as the explicit analytical expressions we obtain for the correlations to be true also for full qcd in appropriate limits.
in a fusion reactor internally coated with liquid metal, it will be important to diagnose the thickness of the liquid at various locations in the vessel, as a function of time, and possibly respond to counteract undesired bulging or depletion.   the electrical conductance between electrodes immersed in the liquid metal can be used as a simple proxy for the local thickness. here a matrix of electrodes is shown to provide spatially and temporally resolved measurements of liquid metal thickness in the absence of plasma.   first a theory is developed for @xmath0 electrodes, and then it is experimentally demonstrated for 3@xmath11 electrodes, as the liquid stands still or is agitated by means of a shaker.   the experiments were carried out with galinstan, but are easily extended to lithium or other liquid metals.
with the development of wireless communication, industrial wireless sensor networks ( iwsns ) plays an important role in monitoring and control systems. in this paper, we extend the application of iwsns into high frequency surface - wave radar ( hfswr ) system.   the traditional antenna is replaced by mobile iwsns. in combination of the application precondition of super - directivity in hf band and circular topology of iwsns,   a super - directivity synthesis method is presented for designing super - directivity array. in this method,   the dominance of external noise is ensured by constraining the ratio of external to internal noise ( rein ) of the array, and the desired side lobe level is achieved by implementing linear constraint. by using this method, the highest directivity will be achieved in certain conditions. using the designed super directive circular array as sub - arrays,   the compact receive antenna array is constructed, the purpose of miniaturization is achieved.   simulation verifies that the proposed method is correct and effective, the validity of the proposed method has been proved.
the issue of which stars may reach the conditions of electron / positron pair formation instability is of importance to understand the final evolution both of the first stars and of contemporary stars.   the criterion to enter the pair instability regime in density and temperature is basically controlled by the mass of the oxygen core.   the main sequence masses that produce a given oxygen core mass are, in turn, dependent on metallicity, mass loss, and convective and rotationally - induced mixing.   we examine the evolution of massive stars to determine the minimum main sequence mass that can encounter pair - instability effects, either a pulsational pair instability ( ppisn ) or a full - fledged pair - instability supernova ( pisn ).   we concentrate on zero - metallicity stars with no mass loss subject to the schwarzschild criterion for convective instability, but also explore solar metallicity and mass loss and the ledoux criterion.   as expected, for sufficiently strong rotationally - induced mixing, the minimum main sequence mass is encountered for conditions that induce effectively homogeneous evolution such that the original mass is converted almost entirely to helium and then to oxygen.   for this case, we find that the minimum main sequence mass is about 40  @xmath0 to encounter ppisn and about 65  @xmath0 to encounter a pisn.   when mass - loss is taken into account those mass limits become 50  @xmath0 for ppisn and 80  @xmath0 for pisn progenitors.   the implications of these results for the first stars and for contemporary supernovae is discussed.   0.57 in
we explore dynamics of cosmological models with bounce solutions evolving on a spatially flat friedmann  lematre  robertson  walker background.   we consider cosmological models that contain the hilbert   einstein curvature term, the induced gravity term with a negative coupled constant, and even polynomial potentials of the scalar field. bounce solutions with non - monotonic hubble parameters have been obtained and analyzed.   the case when the scalar field has the conformal coupling and the higgs potential with an opposite sign is studied in detail. in this model   the evolution of the hubble parameter of the bounce solution essentially depend on the sign of the cosmological constant.
we compute the properties of a class of charged black holes in anti  de sitter space   time, in diverse dimensions.   these black holes are solutions of consistent einstein   maxwell truncations of gauged supergravities, which are shown to arise from the inclusion of rotation in the transverse space.   we uncover rich thermodynamic phase structures for these systems, which display classic critical phenomena, including structures isomorphic to the van der waals  maxwell liquid  gas system. in that case, the phases are controlled by the universal `` cusp '' and `` swallowtail '' shapes familiar from catastrophe theory.   all of the thermodynamics is consistent with field theory interpretations _ via _   holography, where the dual field theories can sometimes be found on the world volumes of coincident rotating branes.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    # 1e^#1
we address nonlocality of a class of fully inseparable three - mode gaussian states generated either by bilinear three - mode hamiltonians or by a sequence of bilinear two - mode hamiltonians.   two different tests revealing strong nonlocality are considered, in which the dichotomic bell operator is represented by displaced parity and by pseudospin operator respectively.   three - mode states are also considered as a conditional source of two - mode non gaussian states, whose nonlocality properties are analyzed.   we found that the non gaussian character of the conditional states allows violation of bell s inequalities ( by parity and pseudospin tests ) stronger than with a conventional twin - beam state.   however, the non gaussian character is not sufficient to reveal nonlocality through a dichotomized quadrature measurement strategy.
in the online graph coloring problem, vertices from a graph @xmath0, known in advance, arrive in an online fashion and an algorithm must immediately assign a color to each incoming vertex @xmath1 so that the revealed graph is properly colored.   the exact location of @xmath1 in the graph @xmath0 is not known to the algorithm.   the _ online chromatic number _ of @xmath0 is the smallest number of colors such that some online algorithm is able to properly color @xmath0 for any incoming order.   we prove that computing the online chromatic number of a graph is pspace - complete.   = 2 = 2     lemma claim observation corollary proposition    # 1
the spreading of an epidemic is determined by the connectiviy patterns which underlie the population.   while it has been noted that a virus spreads more easily on a network in which global distances are small, it remains a great challenge to find approaches that unravel the precise role of local interconnectedness.   such topological properties enter very naturally in the framework of our two - timestep description, also providing a novel approach to tract a probabilistic system.   the method is elaborated for sis - type epidemic processes, leading to a quantitative interpretation of the role of loops up to length 4 in the onset of an epidemic.
we demonstrate experimentally the resonant extinction of thz radiation by a single plasmonic bowtie antenna, formed by two n - doped si monomers with a triangular shape and facing apexes.   this demonstration is achieved by placing the antenna at the output aperture of a conically tapered waveguide, which enhances the intensity of the incident thz field at the antenna position by a factor 10.   the waveguide also suppresses the background radiation that otherwise is transmitted without being scattered by the antenna.   bowtie antennas, supporting localized surface plasmon polaritons, are relevant due to their ability of resonantly enhancing the field intensity at the gap separating the two triangular elements.   this gap has subwavelength dimensions, which allows the concentration of thz radiation beyond the diffraction limit.   the combination of a bowtie plasmonic antenna and a conical waveguide may serve as a platform for far - field thz time - domain spectroscopy of single nanostructures placed in the gap.
we present radio observations of 8 ultracool dwarfs with a narrow spectral type range ( m8-m9.5 ) using the very large array at 8.5  ghz.   only the tight m8 binary lp  349 - 25 was detected.   lp  349 - 25 is the tenth ultracool dwarf system detected in radio and its trigonometric parallax @xmath0  mas, recently measured by gatewood et al., makes it the furthest ultracool system detected by the very large array to date, and the most radio - luminous outside of obvious flaring activity or variability. with a separation of only 1.8  au  , masses of the components of lp  349 - 25 can be measured precisely without any theoretical assumptions ( forveille et al. ), allowing us to clarify their fully - convective status and hence the kind of magnetic dynamo in these components which may play an important role to explain our detection of radio emission from these objects.   this also makes lp  349 - 25 an excellent target for further studies with better constraints on the correlations between x - ray, radio emission and stellar parameters such as mass, age, temperature, and luminosity in ultracool dwarfs.
we study quantum entanglement in the ground state of the affleck - kennedy - lieb - tasaki ( aklt ) model defined on two - dimensional graphs with reflection and/or inversion symmetry.   the ground state of this spin model is known as the valence - bond - solid state.   we investigate the properties of reduced density matrix of a subsystem which is a mirror image of the other one.   thanks to the reflection symmetry, the eigenvalues of the reduced density matrix can be obtained by numerically diagonalizing a real symmetric matrix whose elements are calculated by monte carlo integration.   we calculate the von neumann entropy of the reduced density matrix.   the obtained results indicate that there is some deviation from the naive expectation that the von neumann entropy per valence bond on the boundary between the subsystems is @xmath0.   this deviation is interpreted in terms of the hidden spin chain along the boundary between the subsystems. in some cases where graphs are on ladders,   the numerical results are analytically or algebraically confirmed.
we report on our theoretical investigation considering the widths of quantized hall plateaus ( qhps ) depending on the density asymmetry induced by the large current within the out - of - linear response regime.   we solve the schrdinger equation within the hartree type mean field approximation using thomas fermi poisson nonlinear screening theory.   we observe that the two dimensional electron system splits into compressible and incompressible regions for certain magnetic field intervals, where the hall resistance is quantized and the longitudinal resistance vanishes, if an external current is imposed.   we found that the strong current imposed, induces an asymmetry on the is width depending linearly on the current intensity.   ,   ,    and    edge states, quantum hall effect, out of linear response, rectification 73.20.dx, 73.40.hm, 73.50.-h, 73.61,-r
a recipe for the generalization of the boltzmann equation to a quantum kinetic equation is given for cases in which only level shift and broadening are considered, while coherence phenomena can be neglected.   we also consider a specific problem : hot luminescence from a quantum wire near the threshold for optical phonon emission.   the problem is first discussed within the framework of the boltzmann equation. after pointing out the failure of this description,   the boltzmann equations are generalized to a set of quantum kinetic equations, which in turn are solved in order to describe the luminescence spectra.
we report the serendipitous discovery of an extremely red object in the hubble deep field south ( hdfs ) test nicmos ( near infrared camera and multi object spectrograph ) field of view.   the object is resolved in the nicmos image and has a light profile very well described by an @xmath0 law with effective radius @xmath1 and h@xmath2 magnitudes.   in contrast, the galaxy is undetected in the r and i band ground based images taken at the ctio 4 m blanco telescope, giving a lower limit to the color of ( r - h)@xmath3@xmath4 and ( i - h)@xmath3@xmath5 at the 95 % confidence level.   the colors of a range of synthetic galactic spectra are computed, showing that the object is likely to be an `` old '' elliptical galaxy at redshift @xmath6.   alternatively the colors can be reproduced by an `` old '' elliptical galaxy at somewhat lower redshift ( @xmath7 ) with significant amount of dust, or by a younger galaxy at higher redshift.   this object represents a very interesting target for future vlt observations.
errors in numerical simulations of gravitating systems can be magnified exponentially over short periods of time.   numerical shadowing provides a way of demonstrating that the dynamics represented by numerical simulations are representative of true dynamics. using the sitnikov problem as an example  , it is demonstrated that unstable orbits of the 3-body problem can be shadowed for long periods of time.   in addition, it is shown that the stretching of phase space near escape and capture regions is a cause for the failure of the shadowing refinement procedure.       celestial mechanics, stellar dynamics, methods : numerical
the coherent radiation spectrum of two - level polar molecules with uv transition is studied at the multiphoton resonant excitation by a moderately strong laser field.   the spectrum corresponding to harmonic generation and low - frequency radiation is investigated both analytically and numerically.   specifically, a mechanism for generation of intense smoothly tunable terahertz radiation by two - level molecular configurations ( with dynamic stark shifts ) possessing permanent dipole moments, is considered.
we describe a high speed time - series ccd photometer for the prime focus of the 82-in ( 2.1 m ) telescope at mcdonald observatory, and summarize the observational results we have obtained since it was placed into regular use in february, 2002.   we compare this instrument with the three - channel time - series photometers we have previously used in the asteroseismological study of pulsating white dwarf stars, which used photomultiplier tubes ( pmt ) as the detectors.   we find the ccd instrument is about 9 times more sensitive than the pmt instruments used on the same telescope for the same exposure time.   we can therefore find and measure variable white dwarf stars some 2.4 magnitudes fainter than before, significantly increasing the number of such objects available for study.
bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time.   the overdamped brownian motion of a particle confined in an optical trap is generally modelled by the ornstein - uhlenbeck process and can be observed directly in experiment.   here we present bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates.   this obviates the need for monte carlo sampling and yields methods that are both fast and accurate.   we apply these to experimental data and demonstrate their advantage over commonly used non - bayesian fitting methods.
we report the first measurement of genus curves for the two - dimensional mass map in the neighborhood of rich, x - ray luminous galaxy cluster ms1054 - 03 at @xmath0, reconstructed from weak lensing data obtained by suprime - cam on the prime focus of 8.2 m subaru telescope.   we find that the genus curve measured in the whole survey field deviates from that expected from a random gaussian field.   we show that this non - gaussianity is induced by the rich cluster in this region, and that the genus curve for the region without the cluster is consistent with the prediction for a random gaussian field.   the results demonstrate the feasibility of the genus statistics to examine the non - gaussianity due to the large scale structures and to probe the statistical properties of the large scale clustering.
a simple model of an atomic bose - einstein condensate in a box whose size varies with time is studied to determine the nature of adiabaticity in the nonlinear dynamics obtained within the gross - pitaevskii equation ( the nonlinear schrdinger equation ).   analytical and numerical methods are used to determine the nature of adiabaticity in this nonlinear quantum system.   criteria for validity of an adiabatic approximation are formulated.
until now, just a few extrasolar planets (  30 out of 860 ) have been found through the direct imaging method.   this number should greatly improve when the next generation of high contrast instruments like gemini planet imager ( gpi ) at gemini south telescope or sphere at vlt will became operative at the end of this year.   in particular, the integral field spectrograph ( ifs ), one of the sphere subsystems, should allow a first characterization of the spectral type of the found extrasolar planets. here   we present the results of the last performance tests that we have done on the ifs instrument at the institut de planetologie et dastrophysique de grenoble ( ipag ) in condition as similar as possible to the ones that we will find at the telescope.   we have found that we should be able to reach contrast down to 5x10@xmath0 and make astrometry at sub - mas level with the instrument in the actual conditions. a number of critical issues have been identified.   the resolution of these problems could allow to further improve the performance of the instrument.
what intrinsic properties shape the light curves of type ii supernovae ( sne )? to address this question we derive observational measures that are robust ( i.e., insensitive to detailed radiative transfer ) and   constrain the contribution from, as well as a combination of the envelope mass, progenitor radius, and explosion energy. by applying our methods to a sample of type ii sne from the literature we find that  contribution is often significant. in our sample its contribution to the time weighted integrated luminosity during the photospheric phase ranges between 8% and 72% with a typical value of 30%.   we find that the  relative contribution is anti - correlated with the luminosity decline rate.   when added to other clues, this in turn suggests that the flat plateaus often observed in type ii sne are not a generic feature of the cooling envelope emission, and that without  many of the sne that are classified as ii - p would have shown a decline rate that is steeper by up to 1 mag/100 d. nevertheless, we find that the cooling envelope emission, and not  contribution, is the main driver behind the observed range of decline rates.   furthermore, contrary to previous suggestions, our findings indicate that fast decline rates are not driven by lower envelope masses.   we therefore suggest that the difference in observed decline rates is mainly a result of different density profiles of the progenitors.
cosmology and particle physics come across a tight connection in the attempt to reproduce and understand quantitatively the results of experimental findings.   indeed, the quark gluon plasma ( qgp ) found at colliders and the baryon asymmetry provided by the wmap collaboration are examples where to apply field theoretical techniques in issues relevant for cosmology.    in the simplest leptogenesis framework,   heavy majorana neutrinos are at the origin of the baryon asymmetry.   the non - relativistic regime appears to be relevant during the lepton asymmetry generation where the interactions among particles occur in a thermal medium.   we discuss the development of an effective field theory ( eft ) for non - relativistic majorana particles to address calculations at finite temperature.   we show an application of such a method to the case of a heavy majorana neutrino decaying in a hot and dense plasma of standard model ( sm ) particles.   these techniques are analogous to those widely used for the investigation of heavy - ion collisions at colliders by exploiting hard probes.   finally we sketch some commonalities between majorana neutrinos and bound state of heavy quarks in medium.
we consider three - dimensional gravity based on torsion.   specifically, we consider an extension of the so - called teleparallel equivalent of general relativity in the presence of a scalar field with a self - interacting potential, where the scalar field is non - minimally coupled with the torsion scalar.   then, we find asymptotically ads hairy black hole solutions, which are characterized by a scalar field with a power - law behavior, being regular outside the event horizon and null at spatial infinity and by a self - interacting potential, which tends to an effective cosmological constant at spatial infinity.
weak gravitational lensing has proven to be a powerful tool to map directly the distribution of dark matter in the universe.   the technique, currently used, relies on the accurate measurement of the gravitational shear that corresponds to the first - order distortion of the background galaxy images.   more recently, a new technique has been introduced that relies on the accurate measurement of the gravitational flexion that corresponds to the second - order distortion of the background galaxy images.   this technique should probe structures on smaller scales than that of a shear analysis.   the goal of this paper is to compare the ability of shear and flexion to reconstruct the dark matter distribution by taking into account the dispersion in shear and flexion measurements.   our results show that the flexion is less sensitive than shear for constructing the convergence maps on scales that are physically feasible for mapping, meaning that flexion alone should not be used to do convergence map reconstruction, even on small scales.
the present study is the first such attempt to examine rigorously and comprehensively the spectral properties of a three - dimensional ultracold atom when both the spin - orbit interaction and the zeeman field are taken into account.   the model operator is the rashba spin - orbit coupled operator in dimension three.   the self - adjoint extensions are constructed using the theory of singular perturbations, where regularized rank two perturbations describe spin - dependent contact interactions.   the spectrum of self - adjoint extensions is investigated in detail laying emphasis on the effects due to spin - orbit coupling. when the spin - orbit - coupling strength is small enough  , the asymptotics of eigenvalues is obtained.   the conditions for the existence of eigenvalues above the threshold are discussed in particular.
phase diagram based on the mean square displacement ( msd ) and the distribution of diffusion coefficients of the time - averaged msd for the stored - energy - driven lvy flight ( sedlf ) is presented. in the sedlf,   a random walker can not move while storing energy, and it jumps by the stored energy.   the sedlf shows a whole spectrum of anomalous diffusions including subdiffusion and superdiffusion, depending on the coupling parameter between storing time ( trapping time ) and stored energy.   this stochastic process can be investigated analytically with the aid of renewal theory. here, we consider two different renewal processes, i.e., ordinary renewal process and equilibrium renewal process, when the mean trapping time does not diverge.   we analytically show the phase diagram according to the coupling parameter and the power exponent in the trapping - time distribution.   in particular, we find that distributional behavior of time - averaged msd intrinsically appears in superdiffusive as well as normal diffusive regime even when the mean trapping time does not diverge.
we report for the first time na and o abundances from high - resolution, high @xmath0 echelle spectra of 20 red giants in ngc 2808, taken as part of the science verification program of the flames multi - object spectrograph at the eso vlt. in these stars, spanning about 3 mag from the red giant branch ( rgb ) tip,   large variations are detected in the abundances of oxygen and sodium, anticorrelated with each other ; this is a well known evidence of proton - capture reactions at high temperatures in the on and nena cycles.   one star appears super o - poor ; if the extension of the na - o anticorrelation is confirmed, ngc 2808 might reach o depletion levels as large as those of m 13.   this result confirms our previous findings based on lower resolution spectra ( carretta et al.   2003 ) of a large star - to - star scatter in proton capture elements at all positions along the rgb in ngc 2808, with no significant evolutionary contribution.   finally, the average metallicity for ngc 2808 is @xmath1 dex ( @xmath2 ) from 19 stars.
i describe here the new  ( * c*osmic * a*nisotropy * p*olarization * map*er ) instrument, which performed its first season of observing between february and april 2003 from the crawford hill 7-meter antenna in nj.   is based on the design for the pique instrument, but has better sensitivity and superior angular resolution.
various types of expansions in series of chebyshev - hermite polynomials currently used in astrophysics for weakly non - normal distributions are compared, namely the gram - charlier, gauss - hermite and edgeworth expansions.   it is shown that the gram - charlier series is most suspect because of its poor convergence properties.   the gauss - hermite expansion is better but it has no intrinsic measure of accuracy.   the best results are achieved with the asymptotic edgeworth expansion.   we draw attention to the form of this expansion found by petrov for arbitrary order of the asymptotic parameter and present a simple algorithm realizing petrov s prescription for the edgeworth expansion.   the results are illustrated by examples similar to the problems arising when fitting spectral line profiles of galaxies, supernovae, or other stars, and for the case of approximating the probability distribution of peculiar velocities in the cosmic string model of structure formation.
the effect of magnetic field on the structure properties of hot spin polarized strange quark stars has been investigated. for this purpose  , we use the mit bag model with a density dependent bag constant to calculate the thermodynamic properties of spin polarized strange quark matter such as energy and equation of state.   we see that the energy and equation of state of strange quark matter changes significantly in a strong magnetic field.   finally, using our equation of state, we compute the structure of spin polarized strange quark star at different temperatures and magnetic fields.
we report the first _ chandra _   detection of emission out to the virial radius in the cluster abell  1835 at @xmath0.   our analysis of the soft x - ray surface brightness shows that emission is present out to a radial distance of 10  arcmin or 2.4  mpc, and the temperature profile has a factor of ten drop from the peak temperature of 10  kev to the value at the virial radius.   we model the _ chandra _  data from the core to the virial radius and show that the steep temperature profile is not compatible with hydrostatic equilibrium of the hot gas, and that the gas is convectively unstable at the outskirts.   a possible interpretation of the _ chandra _  data is the presence of a second phase of _ warm - hot _ gas near the cluster s virial radius that is not in hydrostatic equilibrium with the cluster s potential.   the observations are also consistent with an alternative scenario in which the gas is significantly clumped at large radii.        galaxies : clusters : individual ( abell 1835 ) ; cosmology : large - scale structure of universe.
we consider a nonlinear kinetic equation of boltzmann type which takes into account the influence of conviction during the formation of opinion in a system of agents which interact through the binary exchanges introduced in [ g.  toscani, _ commun.   math.   sci. _ * 4 *, 481(2006 ) ]. the original exchange mechanism, which is based on the human tendency to compromise and change of opinion through self - thinking, is here modified in the parameters of the compromise and diffusion terms, which now are assumed to depend on the personal degree of conviction.   the numerical simulations show that the presence of conviction has the potential to break symmetry, and to produce clusters of opinions. the model is partially inspired by the recent work [ l.  pareschi, g.  toscani, _ phil.   trans.   r. soc. a _ * 372 *, 20130396 ( 2014 ) ], in which the role of knowledge in the formation of wealth distribution has been investigated.   # 1     lemma definition proposition remark corollary run example    tt   n r
the effect of damping of spinwaves in a two - dimensional classical ferromagnetic xy model is considered. the damping rate @xmath0 is calculated using the leading diagrams due to the quartic - order deviations from the harmonic spin hamiltonian.   the resulting four - dimensional integrals are evaluated by extending the techniques developed by gilat and others for spectral density types of integrals.   @xmath0 is included into the memory function formalism due to reiter and solander, and menezes, to determine the dynamic structure function @xmath1.   for the infinite sized system, the memory function approach is found to give non - divergent spinwave peaks, and a smooth nonzero background intensity ( `` plateau '' or distributed intensity ) for the whole range of frequencies below the spinwave peak.   the background amplitude relative to the spinwave peak rises with temperature, and eventually becomes higher than the spinwave peak, where it appears as a central peak. for finite - sized systems,   there are multiple sequences of weak peaks on both sides of the spinwave peaks whose number and positions depend on the system size and wavevector in integer units of @xmath2.   these dynamical finite size effects are explained in the memory function analysis as due to either spinwave difference processes below the spinwave peak or sum processes above the spinwave peak.   these features are also found in classical monte carlo  spin - dynamics simulations.   = 1 = 1 = 250 = 350
we present a semi - empirical model for the evolving far - infrared to ultraviolet diffuse background produced by stars in galaxies.   the model is designed to reproduce the results of deep galaxy surveys, and therefore may be considered as a cosmology - independent lower limit to the extragalactic background light. using this model and recent hegra data, we infer the intrinsic spectrum at multi - tev gamma - ray energies for mkn  501 and find that it is consistent with a power law of spectral index @xmath0. in turn, this finding renders it rather unlikely that the present - day infrared background has an intensity as high as claimed by finkbeiner et al.   @xcite.   future 10  gev to tev observations could be used to either constrain the ultraviolet - to - infrared background model at high redshifts or cosmological parameters.
multi - cut critical points and their macroscopic loop amplitudes are studied in the multi - cut two - matrix models, based on an extension of the prescription developed by daul, kazakov and kostov. after identifying possible critical points and potentials in the multi - cut matrix models,   we calculate the macroscopic loop amplitudes in the @xmath0 symmetric background. with a natural large @xmath1 ansatz for the matrix lax operators, a sequence of new solutions for the amplitudes in the @xmath0 symmetric @xmath2-cut two - matrix models   are obtained, which are realized by the jacobi polynomials.   arxiv:0909.1197 + september 2009    * macroscopic loop amplitudes + in the multi - cut two - matrix models *    chuan - tsung chan@xmath3, hirotaka irie@xmath4, sheng - yu darren shih@xmath5 and chi - hsien yeh@xmath4     _ @xmath6department of physics, tunghai university, taiwan, 40704 + @xmath7department of physics and center for theoretical sciences, + national taiwan university, taipei 10617, taiwan, r.o.c + @xmath8department of physics, university of california, berkeley, ca 94720 - 7300 _
consider the problem of pricing options on forwards in energy markets, when spot prices follow a geometric multi - factor model in which several rates of mean reversion appear. in this paper   we investigate the role played by slow mean reversion when pricing and hedging options.   in particular, we determine both upper and lower bounds for the error one makes neglecting low rates of mean reversion in the spot price dynamics.    * keywords : * electricity spot prices, multi - scale mean reversion, delivery period, options on forwards, hedging, pricing error, upper and lower bounds.
among the light nuclear clusters the @xmath0-particle is by far the strongest bound system and therefore expected to play a significant role in the dynamics of nuclei and the phases of nuclear matter. to systematically study the properties of the @xmath0-particle we have derived an effective four - body equation of the alt - grassberger - sandhas ( ags ) type that includes the dominant medium effects, i.e. self energy corrections and pauli - blocking in a consistent way.   the equation is solved utilizing the energy dependent pole expansion for the subsystem amplitudes.   we find that the mott transition of an @xmath0-particle at rest differs from that expected from perturbation theory and occurs at approximately 1/10 of nuclear matter densities.    0.5 in    pacs numbers : 21.45.+v, 21.60.gx, 21.60.jz, 21.65.+f    keywords : @xmath0-particle, four - body equations, nuclear matter, correlations
results for the cross sections of the exclusive @xmath0o(e, e@xmath1pn)@xmath2n and @xmath0o(@xmath3,pn)@xmath2n knockout reactions are presented and discussed in different kinematics. in comparison with earlier work, a complete treatment of the center - of - mass ( cm ) effects in the nuclear one - body current   is considered in connection with the problem of the lack of orthogonality between initial bound and final scattering states.   the effects due to cm and orthogonalization are investigated in combination with different treatments of correlations in the two - nucleon overlap function and for different parametrizations of the two - body currents.   the cm effects lead in super - parallel kinematics to a dramatic increase of the @xmath0o(e, e@xmath1pn ) cross section to the @xmath4 excited state ( 3.95 mev ) of @xmath2n.   in all the situations considered the results are very sensitive to the treatment of correlations. a crucial role is played by tensor correlations, but also the contribution of long - range correlations is important.
a suffix tree is able to efficiently locate a pattern in an indexed string, but not in general the most recent copy of the pattern in an online stream, which is desirable in some applications.   we study the most general version of the problem of locating a most recent match : supporting queries for arbitrary patterns, at each step of processing an online stream.   we present augmentations to ukkonen s suffix tree construction algorithm for optimal - time queries, maintaining indexing time within a logarithmic factor in the size of the indexed string.   we show that the algorithm is applicable to sliding - window indexing, and sketch a possible optimization for use in the special case of lempel - ziv compression.
phase - squeezed light can enhance the precision of optical phase estimation.   the larger the photon numbers are and the stronger the squeezing is, the better the precision will be.   we propose an experimental scheme for generating phase - squeezed light pulses with large coherent amplitudes. in our scheme,   one arm of a single - photon mach   zehnder interferometer interacts with coherent light via a nonlinear optical kerr medium to generate a coherent superposition state.   post - selecting the single photon by properly tuning a variable beam splitter in the interferometer yields a phase - squeezed output.   our proposed scheme is experimentally feasible with current quantum technology.
the recent success of deep neural networks relies on massive amounts of labeled data. for a target task   where labeled data is unavailable, domain adaptation can transfer a learner from a different source domain. in this paper  , we propose a new approach to domain adaptation in deep networks that can simultaneously learn adaptive classifiers and transferable features from labeled data in the source domain and unlabeled data in the target domain.   we relax a shared - classifier assumption made by previous methods and assume that the source classifier and target classifier differ by a residual function.   we enable classifier adaptation by plugging several layers into the deep network to explicitly learn the residual function with reference to the target classifier.   we embed features of multiple layers into reproducing kernel hilbert spaces ( rkhss ) and match feature distributions for feature adaptation.   the adaptation behaviors can be achieved in most feed - forward models by extending them with new residual layers and loss functions, which can be trained efficiently using standard back - propagation.   empirical evidence exhibits that the approach outperforms state of art methods on standard domain adaptation datasets.
in microfluidics, varying wetting properties, expressed in terms of the local slip length, can be used to influence the flow of a liquid through a device.   we study flow past surfaces on which the slip length is modulated in stripes.   we find that the effective slip length for such a flow can be expressed as a function of the individual slip lengths on the stripes.   the angle dependence of the effective slip is in excellent agreement with a recent theory describing the slip length as a tensorial quantity.   this tensorial nature allows to induce a transverse flow, which can be used in micro mixers to drive a vortex. in our simulations of a flow through a square channel with patterned surfaces   we see a homogeneous rotation about the direction of the flow.   we investigate the influence of patterns of cosine shaped varying local slip on the flow field depending on the orientation of the pattern and find the largest effective slip length for periods of stripes parallel to the flow direction.
i address the question of how much of qcd in the chiral limit is reproduced by instantons. after reconstructing the instanton content of smoothed monte carlo lattice configurations,   i compare hadron spectroscopy on this instanton ensemble to the spectroscopy on the original `` physical '' smoothed configurations using a chirally optimised clover fermion action. by studying the zero mode zone in simple instances   i find that the optimised action gives a satisfactory description of it. through the banks - casher formula, instantons by themselves are shown to break chiral symmetry but hadron correlators on the instanton backgrounds are strongly influenced by free quark propagation.   this results in unnaturally light hadrons and a small splitting between the vector and the pseudoscalar meson channels.   superimposing a perturbative ensemble of zero momentum gauge field fluctuations ( torons ) on the instantons is found to be enough to eliminate the free quarks and restore the physical hadron correlators.   i argue that the torons that are present only in finite volumes, are probably needed to compensate the unnaturally large finite size effects due to the lack of confinement in the instanton ensemble.   = 1ex plus0.5ex minus0.2ex    * instantons and chiral symmetry on the lattice * + * tams g. kovcs * + _ instituut - lorentz for theoretical physics, p.o.box 9506 + 2300 ra, leiden, the netherlands _ + e - mail : kovacs@lorentz.leidenuniv.nl +
in this article, we report negative thermal expansion and spin frustration in hexagonal gdino@xmath0. rietveld refinement of the xrd patterns reveal that the negative thermal expansion in the temperature range of 50 - 100k stems from the triangular lattice of gd@xmath1 ions. at low temperature,   the downward deviation of the inverse susceptibility ( @xmath2 ) vs. @xmath3 plot from the curie - weiss law indicates spin frustration which inhibits long - range magnetic ordering down to 2k.   magnetostriction measurements clearly demonstrate a strong spin - lattice coupling. low temperature anomalous phonon softening, as obtained from temperature dependent raman measurements, also reveals the same.   our experimental observations are supported by first principles density functional theory calculations of the electronic and phonon dispersion of gdino@xmath4.   the calculations suggest that the gdino@xmath4 lattice is highly frustrated at low temperature.   further, the calculated normal mode frequencies of the gd related @xmath5 point phonons are found to depend on the magnetic structure of the lattice, suggesting significant magneto - elastic coupling.
using the polish instrument, i am unable to reproduce the large - amplitude polarimetric observations of berdyugina et al.   ( 2008 ) to the @xmath0 confidence level.   i observe no significant polarimetric variability in the hd 189733 system, and the upper limit to variability from the exoplanet is @xmath1 with 99% confidence in the 400 nm to 675 nm wavelength range.   berdyugina et al.   ( 2008 ) report polarized, scattered light from the atmosphere of the hd 189733b hot jupiter with an amplitude of two parts in @xmath2.   such a large amplitude is over an order of magnitude larger than expected given a geometric albedo similar to other hot jupiters.   however, my non - detection of polarimetric variability phase - locked to the orbital period of the exoplanet, and the lack of any significant variability, shows that the polarimetric modulation reported by berdyugina et al.   ( 2008 ) can not be due to the exoplanet.
we propose a location - based beamforming scheme for wiretap channels, where a source communicates with a legitimate receiver in the presence of an eavesdropper.   we assume that the source and the eavesdropper are equipped with multiple antennas, while the legitimate receiver is equipped with a single antenna.   we also assume that all channels are in a rician fading environment, the channel state information from the legitimate receiver is perfectly known at the source, and that the only information on the eavesdropper available at the source is her location.   we first describe how the beamforming vector that minimizes the secrecy outage probability of the system is obtained, illustrating its dependence on the eavesdropper s location.   we then derive an easy - to - compute expression for the secrecy outage probability when our proposed location - based beamforming is adopted.   finally, we investigate the impact location uncertainty has on the secrecy outage probability, showing how our proposed solution can still allow for secrecy even when the source has limited information on the eavesdropper s location.
we study the double exchange model on two lattice sites with one conduction electron in the limit of an infinite hund s interaction.   while this simple problem is exactly solvable, we present an approximate solution which is valid in the limit of large core spins.   this solution is obtained by integrating out charge degrees of freedom.   the effective action of two core spins obtained in the result of such an integration resembles the action of two fractional spins.   we show that the action obtained via naive gradient expansion is inconsistent. however, a `` non - perturbative '' treatment leads to an extra term in the effective action which fixes this inconsistency.   the obtained `` berry phase term '' is geometric in nature.   it arises from a geometric constraint on a target space imposed by an adiabatic approximation.   = 10000
the orbital and radial excitations of light - light mesons are studied in the framework of the dominantly orbital state description.   the equation of motion is characterized by a relativistic kinematics supplemented by the usual funnel potential with a mixed scalar and vector confinement.   the influence of finite quark masses and potential parameters on regge and vibrational trajectories is discussed.   the case of heavy - light mesons is also presented.
we develop a simple and efficient theoretical model to understand the quantum properties of broadband continuous variable quantum teleportation.   we show that, if stated properly, the problem of multimode teleportation can be simplified to teleportation of a single effective mode that describes the input state temporal characteristic. using that model,   we show how the finite bandwidth of squeezing and external noise in the classical channel affect the output teleported quantum field.   we choose an approach that is especially relevant for the case of non - gaussian non - classical quantum states and we finally back - test our model with recent experimental results.
we present optical light curves of five type ia supernovae ( 2002er, 2002fk, 2003cg, 2003du, 2003fk ).   the photometric observations were performed in a set of intermediate - band filters.   sne 2002er, 2003du appear to be normal sn ia events with similar light curve shapes, while sn 2003kf shows the behavior of a brighter sn ia with slower decline rate after maximum.   the light curves of sn 2003cg is unusual ; they show a fast rise and dramatic decline near maximum and do not display secondary peak at longer wavelengths during 15 - 30 days after maximum light.   this suggests that sn 2003cg is likely to be an intrinsically subluminous, 91bg - like sn ia.   exploration of sn ia feature lines through intermediate - band photometry is briefly discussed.
a review of methods for finding general expressions for matrix elements ( non - diagonal with respect to configurations included ) of any one- and two - particle operator for an arbitrary number of shells in an atomic configuration is given.   these methods are compared in various aspects, and the advantages or shortcomings of each particular method are discussed.   efficient method to find the abovementioned quantities in @xmath0 coupling is presented, based on the use of symmetry properties of operators and matrix elements in three spaces ( orbital, spin and quasispin ), second quantization in coupled tensorial form, graphical technique and wick s theorem.   this allows to efficiently account for correlation effects practically for any atom and ion of periodical table.
this first part of special session 5 explored the current status of infrared - based observations of obscured and distant stellar clusters in the milky way galaxy.   recent infrared surveys, either serendipitously or using targeted searches, have uncovered a rich population of young and massive clusters.   however, cluster characterization is more challenging as it must be obtained often entirely in the infrared due to high line - of - sight extinction. despite this, much is to be gained through the identification and careful analysis of these clusters, as they allow for the early evolution of massive stars to be better constrained.   further, they act as beacons delineating the milky way s structure and as nearby, resolved analogues to the distant unresolved massive clusters studied in distant galaxies.
we have formulated the momentum equation for sectorial line driven winds from rotating stars including : ( a ) the oblateness of the star, ( b ) gravity darkening ( von zeipel effect ), ( c ) conservation of angular momentum, ( d ) line driving specified by the force multiplier parameters ( @xmath0, @xmath1, @xmath2 ), ( e ) finite disk correction factors for an oblate star with gravity darkening for both the continuum and the line driving.   the equations are solved numerically.   we calculated the distribution of the mass flux and the wind velocity from the pole to the equator for the winds of b-supergiants.   rotation decreases the terminal velocity in the equatorial region but hardly affects the wind velocity from the poles ; it enhances the mass flux from the poles while the mass flux from the equator remains nearly the same.   these effects increase with increasing rotation rates.   we also calculated models with a bi - stability jump around 25  000 k, using force multipliers recently calculated with a monte carlo technique. in this case the mass flux increases drastically from the pole to the equator and the terminal velocity decreases drastically from pole to equator.   this produces a density contrast in the wind @xmath3 of about a factor 10 independent of the rotation rate of the star.   we suggest that the observed density contrast of a factor @xmath4 of the disks of b stars may be reached by taking into account the wind compression due to the trajectories of the gas above the critical point towards the equatorial plane.
multi - step laser resonance ionization spectroscopy of lutetium ( lu ) has been performed at triumf s off - line laser ion source test stand.   the even - parity rydberg series @xmath0 @xmath1, @xmath0 @xmath2 and @xmath3 @xmath4 were observed converging to the 6s@xmath5 ionization potential.   the experimental results has been compared to previous work.   51 levels of rydberg series @xmath0 @xmath2 and 52 levels of rydberg series @xmath3 @xmath4 were reported new.   additionally six even - parity autoionization ( ai ) series converging to lu ionic states @xmath6 @xmath7 and @xmath6 @xmath8 were observed.   the level energies of these ai states were measured.   the configurations of the ai states were assigned by relativistic multichannel theory ( rmct ) within the framework of multichannel quantum defect theory ( mqdt ).
we present results of analysis of a _   chandra _ observation of cygnusa in which the x - ray hotspots at the ends of the jets are mapped in detail.   a hardness map reveals previously unknown structure in the form of outer and inner hard arcs around the hotspots, with hardness significantly enhanced compared with the hotspot central regions.   the outer hard arcs may constitute the first detection of the bow shock ; the inner hard arcs may reveal where the jets impact on the hotspots.   we argue that these features can not result from electrons radiating by the synchrotron self - compton process.   instead we consider two possible sources of the hard emission : the outer arcs may be due to thermal radiation of hot intracluster gas compressed at the bow shock. alternatively  , both outer and inner arcs may be due to synchrotron radiation of electrons accelerated in turbulent regions highly perturbed by shocks and shear flows.   comparison of measured hardness ratios with simulations of the hardness ratios resulting from these processes show that it is more difficult to explain the observations with a thermal model.   although we can not rule out a thermal model, we argue in favour of the non - thermal explanation.   the hard regions in the secondary hotspots suggest that jet activity is still powering these hotspots.       galaxies : active  galaxies : individual ( cygnusa)x - rays : individual ( cygnusa )
we report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets and. a detailed abundance analysis based on high - resolution spectra yields  @xmath0, @xmath1  k, and @xmath2 for, and  @xmath3, @xmath4  k, and @xmath5 for.   the accuracy of the effective temperatures is supported by a number of independent consistency checks.   the spectroscopic orbital solution for is improved with our new radial - velocity measurements of that system, as are the light - curve parameters for both systems based on newly acquired photometry for and a reanalysis of existing photometry for.   we have redetermined the stellar parameters taking advantage of the strong constraint provided by the light curves in the form of the normalized separation @xmath6 ( related to the stellar density ) in conjunction with our new temperatures and metallicities.   the masses and radii we derive are @xmath7, @xmath8, and @xmath9, @xmath10 for and, respectively. with these revised stellar parameters we obtain improved values for the planetary masses and radii.   we find @xmath11, @xmath12 for, and @xmath13, @xmath14 for.   we confirm as the planet with the largest radius among the currently known transiting hot jupiters.
measuring network flow sizes is important for tasks like accounting / billing, network forensics and security.   per - flow accounting is considered hard because it requires that many counters be updated at a very high speed ; however, the large fast memories needed for storing the counters are prohibitively expensive.   therefore, current approaches aim to obtain approximate flow counts ; that is, to detect large _ elephant _ flows and then measure their sizes.   recently the authors and their collaborators have developed @xcite a novel method for per - flow traffic measurement that is fast, highly memory efficient and accurate. at the core of this method   is a novel counter architecture called `` counter braids. '' in this paper, we analyze the performance of the counter braid architecture under a maximum likelihood ( ml ) flow size estimation algorithm and show that it is optimal ; that is, the number of bits needed to store the size of a flow matches the entropy lower bound.   while the ml algorithm is optimal, it is too complex to implement. in @xcite   we have developed an easy - to - implement and efficient message passing algorithm for estimating flow sizes.
we have shown that the sun s shadow by high energy cosmic rays moves year by year and its behavior is correlated with a time variation of the large - scale structure of the solar and interplanetary magnetic fields.   the solar activity was near minimum in the period from 1996 through 1997. using the data obtained with the tibet air shower array  , we examined the shadowing of cosmic rays by the sun in this quiet phase of solar cycle, and found that the sun s shadow was just in the apparent direction of the sun, though it was observed at the position considerably away from the sun to the south - west in the period between 1990 and 1993.   it is known that the magnetic pole of equivalent solar dipole was reversed during the previous active phase, and near solar minimum the dipole was aligned with the rotating axis, preserving its n - pole on the north pole side of the sun.   this causes the solar magnetic field to shift the sun s shadow to the east.   thus, the observed results suggest that the shift of the sun s shadow due to the solar magnetic field was pushed back by the effect of the geomagnetic field, since the geomagnetic field always make the shadow shift to the west.   we discuss the sun s shadow observed during the period near solar minimum in 1996 - 1997 and compare it with the simulation results.
using data obtained for twelve galaxies as part of the _ spitzer _ infrared nearby galaxies survey ( sings ) and the westerbork synthesis radio telescope ( wsrt)-sings radio continuum survey, we study how star formation activity affects the far - infrared ( fir)radio correlation _ within _ galaxies by testing a phenomenological model which describes the radio image as a smeared version of the fir image.   the physical basis of this description is that cosmic - ray ( cr ) electrons will diffuse measurably farther than the mean free path of dust - heating photons before decaying by synchrotron radiation.   this description works well in general.   galaxies with higher infrared surface brightnesses have best - fit smoothing scale - lengths of a few hundred parsecs, substantially shorter than those for lower surface brightness galaxies.   we interpret this result to suggest that galaxies with higher disk averaged star formation rates have had a recent episode of enhanced star formation and are characterized by a higher fraction of young cr electrons that have traveled only a few hundred parsecs from their acceleration sites in supernova remnants compared to galaxies with lower star formation activity.
while the motion of particles near a rotating, electrically - neutral ( kerr ), and charged ( kerr  newman ) black hole is always strictly regular, a perturbation in the gravitational or the electromagnetic field generally leads to chaos.   the transition from regular to chaotic dynamics is relatively gradual if the system preserves axial symmetry, whereas non - axisymmetry induces chaos more efficiently.   here we study the development of chaos in an oblique ( electro - vacuum ) magnetosphere of a magnetized black hole. besides the strong gravity of the massive source represented by the kerr metric we consider the presence of a weak, ordered, large - scale magnetic field.   an axially - symmetric model consisting of a rotating black hole embedded in an aligned magnetic field is generalized by allowing an oblique direction of the field having a general inclination, with respect to the rotation axis of the system.   the inclination of the field acts as an additional perturbation to the motion of charged particles as it breaks the axial symmetry of the system and cancels the related integral of motion.   the axial component of angular momentum is no longer conserved and the resulting system thus has three degrees of freedom. our primary concern within this contribution is to find out how sensitive the system of bound particles is to the inclination of the field.   we employ the method of the maximal lyapunov exponent to distinguish between regular and chaotic orbits and to quantify their chaoticity.   we find that even a small misalignment induces chaotic motion.
we discuss the magnetic excitations of well - ordered stripe and checkerboard phases, including the high energy magnetic excitations of recent interest and possible connections to the `` resonance peak '' in cuprate superconductors. using a suitably parametrized heisenberg model and spin wave theory, we study a variety of magnetically ordered configurations, including vertical and diagonal site- and bond - centered stripes and simple checkerboards.   we calculate the expected neutron scattering intensities as a function of energy and momentum. at zero frequency,   the satellite peaks of even square - wave stripes are suppressed by as much as a factor of @xmath0 below the intensity of the main incommensurate peaks.   we further find that at low energy, spin wave cones may not always be resolvable experimentally.   rather, the intensity as a function of position around the cone depends strongly on the coupling across the stripe domain walls. at intermediate energy  , we find a saddlepoint at @xmath1 for a range of couplings, and discuss its possible connection to the  resonance peak " observed in neutron scattering experiments on cuprate superconductors. at high energy, various structures   are possible as a function of coupling strength and configuration, including a high energy square - shaped continuum originally attributed to the quantum excitations of spin ladders.   on the other hand, we find that simple checkerboard patterns are inconsistent with experimental results from neutron scattering.    epsf
the group for the development of neutron and gamma detectors in the central institute of engineering, electronics and analytics ( zea-2 ) at forschungszentrum jlich ( fzj ) has developed, in collaboration with european institutes, an anger camera prototype for improving the impact point reconstruction of neutron tracks.   the detector is a chamber filled with @xmath0+@xmath1 gas for neutron capture and subsequent production of a tritium and a proton.   the energy deposition by the ions gives rise to drifting electrons with an avalanche amplification as they approach a micro - strip anode structure.   the scintillating light, generated during the electron drift and avalanche stage, is collected by four vacuum photomultipliers.   the position reconstruction is performed via software algorithms.   the judidt readout electronics was modified at zea-2 to cope with the data acquisition requirements of the prototype.   the results of the commissioning of the electronics are here presented and commented.   forschungszentrum jlich + internal report no  . fzj_2013_02194
the microbunching instability ( @xmath0bi ) usually exists in the linac of a free electron laser ( fel ) facility. in many cases,   the longitudinal space charge ( lsc ) is a dominant factor that generates the instability. for the highly bright electron beams,   the plasma effect is found to be non - trivial in the development of the instability. in this paper,   starting from the vlasov and poisson equations in the multiple - dimensional phase space, we perform the straightforward analysis of the microbunching instability based on the explicit formula of the longitudinal electric field introduced by the density perturbation in the longitudinal direction, in such a way to be highly comparable to the well - developed method for higher energy beams.   this method generally applies in both the cases with and without acceleration and independent of lattice components.   the results show that for a electron beam with small transverse emittance at low energies, which is always the case in the injector of a free electron laser device, the plasma effect results in the oscillation of the longitudinal electric field in the modified plasma frequency that depends on the transverse size of the beam, and the landau damping effect in the longitudinal electric field due to the uncorrelated longitudinal velocity spread during the beam transportation.   these two effects both play important roles in the development of the instability. as the result,   the energy modulation driven by the lsc impedance differs from the regular value significantly and the discrepancy leads to the noticeable change of the final gain of the instability.
the mathematization project investigates students use of mathematical tools across the undergraduate physics curriculum. as a part of this project, we look at intermediate mechanics students written homework solutions to understand how they use those tools in approaching traditional mechanics problems.   we use a modified version of the acer framework to analyze students solutions and to identify patterns of mathematical skills used on traditional problems.   we apply techniques borrowed from network analysis and the resources framework to build a `` fingerprint '' of students mathematical tool use. in this paper, we present preliminary findings on patterns that we identified in students problem solving  .    _ keywords _ : mathematization, undergraduate homework, problem solving, network analysis
by using a dimensionless and varies parameter @xmath0, which is used to determine the neutrinos mass hierarchy, we have investigated the impacts of dark energy on the mass hierarchy.   two typical dark energy models are considered : one is the @xmath1cdm model with a constant equation of state parameter @xmath1 ; the other is the cpl model with a parameterized time - varying equation of state @xmath2. adopting the currently available cosmic observations, and comparing to the @xmath3cdm model  , our study shows that the upper limits of the total neutrino mass @xmath4 is much looser in the @xmath1cdm and cpl model. in the @xmath1cdm ( or cpl ) model the total mass of neutrinos is @xmath5 ev ( or @xmath6 ev ) for the normal mass hierarchy and @xmath7 ev ( @xmath8 ev ) for the inverted mass hierarchy at @xmath9 c.l.. the @xmath1cdm model is slightly favored the normal mass hierarchy, but cpl model has no sympathetic to either.   furthermore, the equation of state parameters of both dark energy models can influence the measurement of @xmath4.   larger @xmath4 may favor phantom dark energy for @xmath1cdm model, and an early phantom but late quintessence dark energy for cpl model.
we present numerical simulations of gravito - inertial waves propagating in radiative zones of rapidly rotating stars.   a first model, using the boussinesq approximation, allows us to study the oscillations of a quasi - incompressible stratified fluid embedded in a rapidly rotating sphere or spherical shell. in a second step,   we investigate the case of a @xmath0 doradus - type star using the anelastic approximation. some fascinating features of rapidly rotating fluids, such as wave attractors, appear in both cases.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present a summary of measurements of strange particle production performed by the experiment na49 in inelastic p+p interactions, as well as semi - central c+c and si+si, central pb+pb, and minimum bias pb+pb collisions in the energy range @xmath0 = 6.3 - 17.3 gev.   new results on @xmath1, @xmath2 and @xmath3 production in minimum bias pb+pb collisions at @xmath0 = 8.7 and 17.3 are shown.   furthermore the strangeness enhancement factor at @xmath0 = 17.3 gev is presented and compared to the results from na57 and star.   energy dependence of strange particle yields normalized to pion yields is presented.   new data on @xmath4 production are shown at @xmath0 = 17.3 gev.   furthermore we present the energy dependence of @xmath5 and @xmath6 fluctuations.   the data are compared with model predictions.
the wmap and planck observations show that the quadrupole and octopole orientations of the cmb might align with each other.   we reveal that the quadrupole   octopole alignment is a natural implication of the primordial power spectrum in an anisotropic spacetime.   the primordial power spectrum is presented with a dipolar modulation.   we obtain the privileged plane by employing the `` power tensor '' technique. at this plane  , there is the maximum correlation between quadrupole and octopole.   the probability for the alignment is much larger than what in the isotropic universe.   we find that this model would lead to deviations from the statistical isotropy only for low@xmath0 multipoles.
we present an analytical theory for the gate electrostatics and the classical and quantum capacitance of the graphene nanoribbons ( gnrs ) and compare it with the exact self - consistent numerical calculations based on the tight - binding @xmath0-orbital hamiltonian within the hartree approximation.   we demonstrate that the analytical theory is in a good qualitative ( and in some aspects quantitative ) agreement with the exact calculations.   there are however some important discrepancies. in order to understand the origin of these discrepancies we investigate the self - consistent electronic structure and charge density distribution in the nanoribbons and relate the above discrepancy to the inability of the simple electrostatic model to capture the classical gate electrostatics of the gnrs. in turn, the failure of the classical electrostatics is traced to the quantum mechanical effects leading to the significant modification of the self - consistent charge distribution in comparison to the non - interacting electron description. the role of electron - electron interaction in the electronic structure and the capacitance of the gnrs   is discussed.   our exact numerical calculations show that the density distribution and the potential profile in the gnrs are qualitatively different from those in conventional split - gate quantum wires ; at the same time, the electron distribution and the potential profile in the gnrs show qualitatively similar features to those in the cleaved - edge overgrown quantum wires.   finally, we discuss an experimental extraction of the quantum capacitance from experimental data.
the optical scattering coefficient of a dilute, well solubilised eumelanin solution has been accurately measured as a function of incident wavelength, and found to contribute less than @xmath0 of the total optical attenuation between 210 and 325 nm. at longer wavelengths ( 325 nm to 800 nm ) the scattering was less than the minimum sensitivity of our instrument.   this indicates that uv and visible optical density spectra can be interpreted as true absorption with a high degree of confidence.   the scattering coefficient vs wavelength was found to be consistent with rayleigh theory for a particle radius of @xmath1 nm.   @xmath2 soft condensed matter group and centre for biophotonics and laser science, @xmath3 condensed matter theory group, physics department, university of queensland, st.   lucia, brisbane, qld 4072, australia
the counterfactuality of the recently proposed protocols for direct quantum communication is analyzed.   it is argued that the protocols can be counterfactual only for one value of the transmitted bit.   the protocols achieve a reduced probability of detection of the particle in the transmission channel by increasing the number of paths in the channel. however, this probability is not lower than the probability of detecting a particle actually passing through such a multi - path channel, which was found to be surprisingly small.   the relation between security and counterfactuality of the protocols is discussed.   an analysis of counterfactuality of the protocols in the framework of the bohmian interpretation is performed.
using a quantum theory including spin - splitting effect in diluted magnetic semiconductors, we study the dependence of tunneling magnetoresistance ( tmr ) on barrier thickness, temperature and applied voltage in gamnas / gaas / gamnas heterostructures.   tmr ratios more than 65% are obtained at zero temperature, when one gaas monolayer ( @xmath0 0.565 nm ) is used as a tunnel barrier.   it is also shown that the tmr ratio decreases rapidly with increasing the barrier thickness and applied voltage, however at high voltages and low thicknesses, the tmr first increases and then decreases.   our model calculations well explain the main features of the recent experimental observations.
according to the harrison - zeldovich prescription, the amplitude of matter density perturbations at horizon crossing is the same at all scales. based on this prescription, we show how to construct the matter power spectrum of generic dark energy models from the power spectrum of a @xmath0cdm model without the need of solving in full the dynamical equations describing the evolution of all energy density perturbations.   our approach allows to make model predictions of observables that can be expressed in terms of the matter power spectrum alone, such as the amplitude of matter fluctuations, peculiar velocities, cosmic microwave background temperature anisotropies on large angular scales or the weak lensing convergence spectrum.   then, models that have been tested only at the background level using the rate of the expansion of the universe can now be tested using data on gravitational clustering and on large scale structure.   this method can save a lot of effort in checking the validity of dark energy models. as an example of the accurateness of the approximation used,   we compute the power spectrum of different dark energy models with constant equation of state parameter ( @xmath1, @xmath2 and @xmath3, ruled out by observations but easy to compare to numerical solutions ) using our methodology and discuss the constraints imposed by the low multipoles of the cosmic microwave background.
in this extended abstract we provide a unifying framework that can be used to characterize and compare the expressive power of query languages for different data base models.   the framework is based upon the new idea of _ valid _ partition, that is a partition of the elements of a given data base, where each class of the partition is composed by elements that can not be separated ( distinguished ) according to some level of information contained in the data base.   we describe two applications of this new framework, first by deriving a new syntactic characterization of the expressive power of relational algebra which is equivalent to the one given by paredaens, and subsequently by studying the expressive power of a simple graph - based data model.            proposition corollary 
a satisfactory understanding of the origin of the dependence of galaxy properties on their environment has remained, so far, out of reach. in the light of numerous observational results and substantial theoretical progress obtained for clusters of galaxies in the last years, a primary goal is to understand how the star formation activity depends on cluster substructure, i.e. on the merging / accretion history of a cluster. in this contribution we present a case   in which it is possible to identify the cluster environment, and in particular the intracluster medium and the recent infall history of galaxies onto the cluster, as the cause for an abrupt change in the star formation histories of a subset of galaxies in the coma cluster.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study a simple model describing superradiance in a system of two - level atoms interacting with a single - mode bosonic field.   the model permits a continuous crossover between integrable and partially chaotic regimes and shows a complex thermodynamic and quantum phase structure.   several types of excited - state quantum phase transitions separate quantum phases that are characterized by specific energy dependences of various observables and by different atom  field and atom  atom entanglement properties.   we observe an approximate revival of some states from the weak atom   field coupling limit in the strong coupling regime.    single - mode superradiance model, excited - state quantum phase transitions, thermal and quantum phases, entanglement properties of excited states
in social systems, people communicate with each other and form groups based on their interests.   the pattern of interactions, the network, and the ideas that flow on the network naturally evolve together.   researchers use simple models to capture the feedback between changing network patterns and ideas on the network, but little is understood about the role of past events in the feedback process. here   we introduce a simple agent - based model to study the coupling between peoples ideas and social networks, and better understand the role of history in dynamic social networks.   we measure how information about ideas can be recovered from information about network structure and, the other way around, how information about network structure can be recovered from information about ideas.   we find that it is in general easier to recover ideas from the network structure than vice versa.
a detailed and systematic density - functional theory ( dft ) study of a series of early transition - metal carbides ( tmc s ) in the nacl structure is presented.   the focus is on the trends in the electronic structure and nature of bonding, which are essential for the understanding of the reactivity of tmc s.   the employed approach is based on a thorough complementary analysis of the electron density differences, the density of states ( dos ), the band structure, and the real - space wave functions to gain insight into the bonding of this class of materials and get a more detailed picture of it than previously achieved, as the trend study allows for a systematic identification of the bond character along the different bands.   our approach confirms the presence of both the well - known tm   c and tm  tm bonds and, more importantly, it shows the existence and significance of direct c   c bonds in all investigated tmc s, which are frequently neglected but have been recently identified in some cases [ solid state commun. *   121 *, 411 ( 2002 ) ; phys.   rev.   b * 75 *, 235438 ( 2007 ) ]. new information on the spatial extent of the bonds,   their _ k_-space location within the band structure, and their importance for the bulk cohesion is provided.   trends in covalency and ionicity are presented.   the resulting electron - structural trends are analyzed and discussed within a two - level model.
we report the detection of a new radio transient source, gcrt  j1746@xmath02757, located only 11 north of the galactic center.   consistent with other radio transients toward the galactic center, this source brightened and faded on a time scale of a few months.   no x - ray counterpart was detected.   we also report new 0.33  ghz measurements of the radio counterpart to the x - ray transient source, xte  j1748@xmath0288, previously detected and monitored at higher radio frequencies.   we show that the spectrum of xte  j1748@xmath0288  steepened considerably during a period of a few months after its peak.   we also discuss the need for a more efficient means of finding additional radio transients.
emission lines in ionized nebulae can provide strong and useful constraints on the properties of both ionizing and non - ionizing stellar populations in regions with star formation, provided that stellar evolution and stellar atmosphere models can be used in a selfconsistent way.   recently, the application of these techniques has shown important discrepancies between predicted and observed nebular spectra that point to stellar atmosphere models of wr stars which are too energetic and/or to a significant leakage of high energy photons. in this contribution   these two alternatives are analyzed in detail.
we show how it is possible to suppress decoherence using tailored external forcing acting as pulses. in the limit of infinitely frequent pulses decoherence and dissipation   are completely frozen ; however, a significant decoherence suppression is already obtained when the frequency of the pulses is of the order of the reservoir typical frequency scale.   this method could be useful in particular to suppress the decoherence of the center - of - mass motion in ion traps.
transiting planet discoveries have largely been restricted to the short - period or low - periastron distance regimes due to the bias inherent in the geometric transit probability. through the refinement of planetary orbital parameters, and hence reducing the size of transit windows, long - period planets become feasible targets for photometric follow - up. here   we describe the terms project that is monitoring these host stars at predicted transit times.
the range resolution in conventional continuous time frequency modulation ( ctfm ) is inversely proportional to the signal bandwidth.   the dual - demodulator continuous time frequency modulation ( dd - ctfm ) processing technique was proposed by gough et al @xcite as a method to increase the range resolution by making the output of dd - ctfm truly continuous.   however, it has been found that in practice the range resolution is still limited by the signal bandwidth.   the limitation of dd - ctfm has been explained using simulations and mathematically in this paper.   dd - ctfm, range resolution, blind time.
we report phase - resolved optical polarimetric, photometric and spectroscopic observations of  (= euve j211558.6, craig 1996 ) which confirms the system to be a magnetic cataclysmic binary of the polar ( am herculis ) subclass.   the optical light curve is sometimes flat and occasionally displays a pronounced bright phase, reminiscent of the self - eclipse of a small accretion spot by the revolving white dwarf, as seen in self - eclipsing polars.   our period search reveals ambiguous results only which can be interpret assuming that the white dwarf is not synchronously rotating with the binary orbit.   we find circularly polarized cyclotron radiation with @xmath0 ranging from 0% to @xmath1 on one occasion, from @xmath2% to @xmath3 on another occasion. compared with other polars, the self - occulted accretion region of  had an extreme red cyclotron spectrum. in addition, the system has an extreme hard x - ray colour during the rosat all - sky survey observation.   both properties suggest a low value of the magnetic field strength, and our best estimate gives @xmath4 mg.   due to the absence of significant m - star features in our low - resolution spectra we estimate the minimum distance to  to be @xmath5pc ( for an m@xmath6 secondary star ).   2heii@xmath74686 1hei@xmath74471
we study community structure of networks. we have developed a scheme for maximizing the modularity @xmath0 @xcite based on mean field methods.   further, we have defined a simple family of random networks with community structure ; we understand the behavior of these networks analytically. using these networks, we show how the mean field methods display better performance than previously known deterministic methods for optimization of @xmath0.
in this paper we consider the application of electromagnetic theory to the analysis of the scanning near - field optical microscope ( snom ) in order to predict experimentally observable quantities such as the transmission or reflection coefficients for a particular tip - surface configuration.   in particular we present the first application of a transfer matrix based calculation to this challenging problem by using an adaptive co - ordinate transformation to accurately model the shape of the snom tip.   we also investigate the possibility of increasing the transmitted light through the snom tip by introducing a metal wire into the centre of the tip.   this converts the tip into a co - axial cable.   we show that, in principle, this can dramatically improve the transmission characteristics without having a detrimental effect on the resolution.
we investigate the photon statistics of light transmitted from a driven optical cavity containing one or two atoms interacting with a single mode of the cavity field.   we treat arbitrary driving fields with emphasis on departure from previous weak field results. in addition effects of dephasing due to atomic transit through the cavity mode   are included using two different models.   we find that both models show the nonclassical correlations are quite sensitive to dephasing.   the effect of multiple atoms on the system dynamics is investigated by placing two atoms in the cavity mode at different positions, therefore having different coupling strengths.
we present a framework to generate the hierarchical flavor structure of standard model quarks and leptons from loops of superpartners.   the simplest model consists of the minimal supersymmetric standard model with tree level yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. agreement with constraints from low energy flavor observables, in particular kaon mixing, is obtained for supersymmetric particles with masses at the pev scale or above. in our framework   both the second and the first generation fermion masses are generated at 1-loop. despite this, a novel mechanism generates a hierarchy among the first and second generations without imposing a symmetry or small parameters  . a second - to - first generation mass ratio of order 100 is typical.   the minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing.   the minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low.   we discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and yukawa coupling unification.
the percolation threshold and wrapping probability @xmath0 for the two - dimensional problem of continuum percolation on the surface of a klein bottle have been calculated by the monte carlo method with the newman   ziff algorithm for completely permeable disks.   it has been shown that the percolation threshold of disks on the klein bottle coincides with the percolation threshold of disks on the surface of a torus, indicating that this threshold is topologically invariant.   the scaling exponents determining corrections to the wrapping probability and critical concentration owing to the finite - size effects are also topologically invariant. at the same time, the quantities @xmath0 are different for percolation on the torus and klein bottle and are apparently determined by the topology of the surface.   furthermore, the difference between the @xmath0 values for the torus and klein bottle means that at least one of the percolation clusters is degenerate.   : percolation theory, percolation cluster, wrapping probability
we compare red clump stars with parallaxes known to better than 10% in the hipparcos catalog and corrected for the interstellar extinction, with the ogle red clump stars in baade s window also corrected for the interstellar extinction.   there are @xmath0 and @xmath1 such stars in the two data sets, respectively.   we find empirically that the average i - band magnitude of red clump stars does not depend on their intrinsic color in the range @xmath2.   the red clump luminosity function is well represented by a gaussian with the peak at @xmath3, and the dispersion @xmath4 mag.   this allows a single step determination of the distance to the galactic center and gives @xmath5 kpc.   the number of red clump stars is so large that a formal statistical error is only @xmath6.   the local stars are relatively blue and have a small color dispersion : @xmath7, @xmath8, while for the bulge stars @xmath9, @xmath10.   presumably, the bulge population has a broader range and a higher average metallicity than the local disk population.
a general algorithm for handling the energy dependence of meson - nucleon amplitudes in the nuclear medium has been recently applied to antikaons and to eta mesons. here   we test this approach on @xmath0 amplitudes in pionic atoms where direct comparison can be made with ample experimental results. applying this algorithm to a large - scale fit of 100 pionic - atom data points across the periodic table, which also include the ` deeply - bound'states in sn and pb,   reaffirms earlier conclusions on the density - dependent renormalization of the @xmath0 threshold isovector amplitude @xmath1, or equivalently the renormalization of the pion decay constant @xmath2 in the nuclear medium.   pion - nucleon in - medium interaction, energy dependence, pionic atoms
we calculate the bi - photon state generated by spontaneous parametric down conversion in a thin crystal and under collinear phase matching conditions using a pump consisting of any superposition of laguerre - gauss modes.   the result has no restrictions on the angular or radial momenta or, in particular, on the width of the pump, signal and idler modes.   we demonstrate the strong effect of the pump to signal / idler width ratio on the composition of the down - converted entangled fields.   knowledge of the pump to signal / idler width ratio is shown to be essential when calculating the maximally entangled states that can be produced using pumps with a complex spatial profile.
a length-@xmath0 spin chain with the @xmath1-th neighbor interaction is identical to a two - dimensional ( @xmath2 ) model under the screw - boundary ( sb ) condition.   the sb condition provides a flexible scheme to construct a @xmath3 cluster from an arbitrary number of spins ; the numerical diagonalization combined with the sb condition admits a potential applicability to a class of systems intractable with the quantum monte carlo method due to the negative - sign problem.   however, the simulation results suffer from characteristic finite - size corrections inherent in sb. in order to suppress these corrections  , we adjust the screw pitch @xmath4 so as to minimize the excitation gap for each @xmath0.   this idea is adapted to the transverse - field ising model on the triangular lattice with @xmath5 spins. as a demonstration  , the correlation - length critical exponent @xmath6 is analyzed rather in detail.
brown dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics.   these clouds are globally neutral obeying dust - gas charge equilibrium which is, on short time scales, inconsistent with the observation of stochastic ionisation events of the solar system planets.   we argue that a significant volume of the clouds in brown dwarfs and extrasolar planets is susceptible to local discharge events.   these are electron avalanches triggered by charged dust grains.   such intra - cloud discharges occur on time scales shorter than the time needed to neutralise the dust grains by collisional processes.   an ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large - scale magnetic field.
the scattering of a fermion in the background of a smooth step potential is considered with a general mixing of vector and scalar lorentz structures with the scalar coupling stronger than or equal to the vector coupling.   charge - conjugation and chiral - conjugation transformations are discussed and it is shown that a finite set of intrinsically relativistic bound - state solutions appears as poles of the transmission amplitude. it is also shown that those bound solutions disappear asymptotically as one approaches the conditions for the realization of the so - called spin and pseudospin symmetries in a four - dimensional space - time.
the dielectric engineered tunnel field - effect transistor ( de - tfet ) as a high performance steep transistor is proposed. in this device, a combination of high - k and low - k dielectrics results in a high electric field at the tunnel junction. as a result   a record on - current of about 1000 ua / um and a subthreshold swing ( ss ) below 20mv / dec are predicted for wte@xmath0 de - tfet. the proposed tfet works based on a homojunction channel and electrically doped contacts both of which are immune to interface states, dopant fluctuations, and dopant states in the band gap which typically deteriorate the off - state performance and ss in conventional tfets.   tfets, dielectric engineering, electrical doping.
a new formalism to calculate the transmission coefficient @xmath0 of electrons from a material @xmath1 into the same material @xmath1 through a barrier @xmath2 is presented.   the barrier @xmath2 is arbitrary and can be metallic, semiconducting or insulating.   the important feature of this formalism is that it starts from the electronic structure of a periodic @xmath3/@xmath2 superlattice.   the electronic stucture of such a superlattice is calculated selfconsistently within a screened korringa - kohn - rostoker method.   the capability of the new method is demonstrated by means of a free electron model. first results for the transmission of cu electrons through a co layer   are presented.   acknowledgement algorithm axiom claim conclusion condition conjecture corollary criterion definition example exercise lemma notation problem proposition remark solution summary
in this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant.   first, we briefly review the ` classical'hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations.   then we re - formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity.   based on this re - formulation in the framework of nonequilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for ( i ) nonlinear equations of state, ( ii ) surfactant - dependent wettability, ( iii ) surfactant phase transitions, and ( iv ) substrate - mediated condensation. in passing,   we discuss important differences to most of the models found in the literature.
we present the palomar transient factory discoveries and the photometric and spectroscopic observations of ptf11kmb and ptf12bho.   we show that both transients have properties consistent with the class of calcium - rich gap transients, specifically lower peak luminosities and rapid evolution compared to ordinary supernovae, and a nebular spectrum dominated by  emission.   a striking feature of both transients is their host environments : ptf12bho is an intra - cluster transient in the coma cluster, while ptf11kmb is located in a loose galaxy group, at a physical offset @xmath0  kpc from the most likely host galaxy.   deep subaru imaging of ptf12bho rules out an underlying host system to a limit of @xmath1, while _ hubble space telescope _   imaging of ptf11kmb reveals a marginal counterpart that, if real, could be either a background galaxy or a globular cluster.   we show that the offset distribution of ca - rich gap transients is significantly more extreme than that seen for type ia supernovae or even short - hard gamma - ray bursts ( sgrbs ).   thus, if the offsets are caused by a kick, they require larger kick velocities and/or longer merger times than sgrbs.   we also show that almost all ca - rich gap transients found to date are in group and cluster environments with elliptical host galaxies, indicating a very old progenitor population ; the remote locations could partially be explained by these environments having the largest fraction of stars in the intra - group / intra - cluster light following galaxy - galaxy interactions.
the understanding of the relationship between excitation parameters and oscillation regimes is a classical topic concerning bowed string instruments. for reed instruments, results are less numerous.   nevertheless it is interesting to know the range of parameters for which sound can be produced or not, and if the emergence and extinction bifurcations are direct or not, with consequences on the pianissimo playing and more generally on the ease of playing.    in the minimum model of clarinet - like instruments,   three parameters are considered : i ) the mouth pressure, ii ) the reed opening at rest, iii ) the length of the resonator  assumed to be cylindrical.   recently a supplementary parameter was added : the loss parameter of the resonator ( using the raman model, that considers resonator losses to be independent of frequency ).   this allowed explaining the extinction of sound when the mouth pressure becomes very large.   the present paper presents an extension of the paper by dalmont et al ( jasa, 2005 ), searching for a diagram of oscillation regimes with respect to the reed opening and the loss parameter.   an alternative method is used, which allows easier generalization.   the emphasis is done on the emergence bifurcation : for very strong losses, it can be inverse, similarly to the extinction one for weak losses.   the main part of the calculations are analytical, giving clear dependence of the parameters.   an attempt to deduce musical consequences for the player is given.   keywords : bifurcations, reed musical instruments, clarinet, acoustics.
the space density of white dwarfs is highly uncertain even nearby.   this results from the fact that the known sample of white dwarfs is largely incomplete in part because most white dwarfs have been discovered as by - products in non - dedicated surveys. in order to obtain more accurate white dwarf space densities and scale heights   we must build up a complete sample of white dwarfs.   the european galactic plane surveys ( egaps ) are the best database to search for white dwarfs as they will provide broad band ( u, g, r, i ) and narrow band ( h@xmath0 and hei ) measurements for one per cent of all the stars in the galaxy. by looking at the galactic plane, where most stars are, we ensure that we are obtaining a complete sample.   the space densities obtained from egaps can then be compared with those found in high latitude surveys such as the sloan digital sky survey ( sdss ).   the methods used to identify white dwarfs using the colours available in egaps are described and some preliminary results presented.
we discuss some social contagion processes to describe the formation and spread of radical opinions in the spirit of previous work by serge galam.   the dynamics of opinion spread involves local threshold processes as well as mean field effects.   we calculate and observe phase transitions in the dynamical variables resulting in a rapidly increasing number of passive supporters.   this strongly indicates that military solutions are inappropriate.   friedrich august@xmath0, philippe blanchard@xmath1, sascha delitzscher@xmath2, gerald hiller@xmath0, tyll krueger@xmath2    _ @xmath0 dept of mathematics, tu berlin, d-10623 berlin, germany _    _   @xmath1 dept of physics, university bielefeld, d-33615 bielefeld, germany _
transmission of information over a discrete - time memoryless rician fading channel is considered where neither the receiver nor the transmitter knows the fading coefficients. the spectral - efficiency / bit - energy tradeoff in the low - power regime   is examined when the input has limited peakedness. it is shown that if a fourth moment input constraint is imposed or the input peak - to - average power ratio is limited, then in contrast to the behavior observed in average power limited channels, the minimum bit energy is not always achieved at zero spectral efficiency.   the low - power performance is also characterized when there is a fixed peak limit that does not vary with the average power.   a new signaling scheme that overlays phase - shift keying on on - off keying is proposed and shown to be optimally efficient in the low - power regime.   + _ index terms _ : fading channels, memoryless fading, rician fading, peak constraints, spectral efficiency, low - power regime.    1.5    1.5
we discuss multichannel inelastic rescatterring effects in @xmath0 decays into a pair @xmath1 of pseudoscalar mesons ( @xmath2 or @xmath3 ). in agreement with short - distance models   it is assumed that initially @xmath0 meson decays dominantly into jet - like states composed of two flying - apart low - mass resonances @xmath4 which rescatter into @xmath1.   since from all s - matrix elements @xmath5 involving @xmath1 only some ( @xmath6 ) contribute to the final state rescatterring, the latter is treated as a correction only.   the rescatterring of resonance pair @xmath4 into the final @xmath1 state is assumed to proceed through regge exchange.   although effects due to a single intermediate state @xmath4 are small, it is shown that the combined effect of all such states should be large. in particular, amplitudes of @xmath0   decays into @xmath3 become significantly larger than those estimated through short - distance penguin diagrams, to the point of being comparable to the @xmath7 amplitudes.   = -0.1 in = 14.6 cm = 8.99 in    pacs numbers : 13.25.hw,11.80.gw,12.40.nn,12.15.hh + @xmath8 e - mail : zenczyko@solaris.ifj.edu.pl    report # 1849/ph, inp - krakw
we model the light - curves from radiation - driven clouds near an accreting black hole. taking into account the multiple images due to strong gravitational lensing  , we find that sharp spikes can significantly enhance the observed flux.   following our previous work ( hork & karas 2006a, b ) we assume that scattering of ambient light takes place in a cloud that is in radial motion under a combined influence of black hole gravity and the radiation field.   the retro - lensed photons give rise to peaks in the observed signal that follow with a characteristic time lag after the direct - image photons.   duration of these features is very short and the predicted polarization varies abruptly on the time - scale comparable with the light - crossing time of the system  a signature of the photon orbit.   we also consider the polarization properties of scattered light.
we present a deterministic scheme for generating large - scale atomic w states in cavity qed system via a simple expansion mechanism, which is realized only by a detuned interaction between two identical atoms and a vacuum cavity mode. with the presented scheme,   a w - type bell pair can be created and an @xmath0-atom w state can be expanded to a @xmath1-atom w state with a unit probability of success in principle.   no multi - atom gates, quantum memories or quantum non - demolition measurements are required, greatly simplifying the experimental realization of the scheme.   the feasibility analysis shows that our expansion scheme can be implemented with state - of - the - art technologies.   our scheme enables advances not only in quantum information and communication but also in quantum thermodynamics, where atomic w states plays a crucial role.
several progresses have been done very recently on models for the dynamics of one or more vortex filaments in 3-d fluids. in this article   we survey the recent and previous results in this topic.   we finally present a collection of new situations of filaments collapse.
we report a simple method for the fabrication of niobium superconducting ( sc ) tips for scanning tunnelling microscopy which allow atomic resolution.   the tips, formed in - situ by the mechanical breaking of a niobium wire, reveal a clear sc gap of 1.5 mev and a critical temperature t@xmath0=9.2@xmath10.3 k, as deduced from superconductor insulator normal metal ( nis ) and superconductor insulator superconductor ( sis ) spectra.   these match the values of bulk nb samples.   we systematically find an enhanced value of the critical magnetic field in which superconductivity in the tip is destroyed ( around 1 t for some tips ) up to five times larger than the critical field of bulk nb ( 0.21 t ).   such enhancement is attributed to a size effect at the tip apex.   ,   ,   ,   ,   ,    and    scanning tunnelling microscopy, superconducting tip, critical field    68.37.ef, 74.25.op, 74.50+r, 74.78.nd
in this communication, a simple mechanism in the optional public goods game is experimentally investigated using two experimental settings ; and first time, the cyclic strategy pattern in full state space is demonstrated by means of velocity.   it is, furthermore, elaborated that the strategies of cooperation, defection and nonparticipant form a rock - paper - scissors type cycle, and the cycle of three strategies are persistent over 200 rounds.   this cycle is very similar to the cycle given by evolutionary dynamics e.g. replicator dynamics.   the mechanism that nonparticipant can sustain cooperation is driven by the rock - paper - scissors type of cyclic dominance in the three strategies.   that is, if the cycle is existent, the cooperation will always sustain.   meanwhile, the distribution of social states changes in the state space and from cooperation as the most frequent strategy to defection and, from defection to nonparticipant, forms a clear rotation path in a long run.   these results seem to implicate that the evolutionary dynamics has ability to capture the real dynamics applying not only on biosphere, but also on human society.    optional public goods game ; rock - paper - scissors ; evolution of cooperation ; cyclic strategies ; evolution of distribution ; experimental economics ;
in this paper, we present an algorithm for rapid bayesian analysis that combines the benefits of nested sampling and artificial neural networks. the blind accelerated multimodal bayesian inference ( bambi )   algorithm implements the multinest package for nested sampling as well as the training of an artificial neural network ( nn ) to learn the likelihood function. in the case of computationally expensive likelihoods  , this allows the substitution of a much more rapid approximation in order to increase significantly the speed of the analysis.   we begin by demonstrating, with a few toy examples, the ability of a nn to learn complicated likelihood surfaces.   bambi s ability to decrease running time for bayesian inference is then demonstrated in the context of estimating cosmological parameters from _ wilkinson microwave anisotropy probe _ and other observations.   we show that valuable speed increases are achieved in addition to obtaining nns trained on the likelihood functions for the different model and data combinations.   these nns can then be used for an even faster follow - up analysis using the same likelihood and different priors.   this is a fully general algorithm that can be applied, without any pre - processing, to other problems with computationally expensive likelihood functions.       methods : data analysis  methods : statistical  cosmological parameters
we calculate the differential cross section and single - polarization observables for the reaction @xmath0 within perturbative qcd, treating the proton as a quark - diquark system.   the phenomenological couplings of gauge bosons to ( spatially extended ) diquarks and the quark - diquark distribution amplitude of the proton are adopted from previous investigations of baryon form factors and two - photon processes. going beyond leading order, we take into account hadron - mass effects by means of a systematic expansion in the small parameter ( hadron mass/ photon energy ). with the @xmath1-meson distribution amplitude taken from the literature our predictions for the differential cross section at @xmath2 seem to provide a reasonable extrapolation of the low-@xmath3 data and are also comparable in magnitude with the results of a two - gluon exchange model in which the gluons are considered as a remnant of the pomeron. for momentum transfers of a few gev   hadron - mass effects appear still to be sizeable.    #
to make a useful stt - mram ( spin - transfer torque magnetoresistive random - access memory ) device, it is necessary to be able to calculate switching rates, which determine the error rates of the device. in a single - macrospin model, one can use a fokker - planck equation to obtain a low - current thermally activated rate @xmath0. here the effective energy barrier @xmath1 scales with the single - macrospin energy barrier @xmath2, where @xmath3 is the effective anisotropy energy density and @xmath4 the volume. a long - standing paradox in this field   is that the actual energy barrier appears to be much smaller than this.   it has been suggested that incoherent motions may lower the barrier, but this has proved difficult to quantify. in the present paper,   we show that the coherent precession has a magnetostatic instability, which allows quantitative estimation of the energy barrier and may resolve the paradox.
the measurement of @xmath0 for psr j1614 - 2230 and @xmath1 for psr j0348 + 0432 puts a strong constraint on the neutron star equation of state and its exotic composition at higher densities. in this paper  , we investigate the possibility of exotic equation of state within the observational mass constraint of @xmath2 in the framework of relativistic mean field model with density - dependent couplings.   we particularly study the effect of antikaon condensates in the presence of hyperons on the mass - radius relationship of the neutron star.
we present the energy eigenvalues of a quantum bouncer in the framework of the generalized ( gravitational ) uncertainty principle ( gup ) via quantum mechanical and semiclassical schemes. in this paper, we use two equivalent nonperturbative representations of a deformed commutation relation in the form @xmath0=i\hbar(1+\beta p^2)$ ] where @xmath1 is the gup parameter.   the new representation is formally self - adjoint and preserves the ordinary nature of the position operator.   we show that both representations result in the same modified semiclassical energy spectrum and agrees well with the quantum mechanical description.   _ keywords _ : quantum gravity ; generalized uncertainty principle ; quantum bouncer ; minimal length.    _   pacs _ : 04.60.-m
transmission of terahertz waves through a thin layer of the superconductor nbn deposited on an anisotropic r - cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample.   a significant difference is found between transmitted intensities of beams linearly polarized parallel with and perpendicular to the direction of applied magnetic field.    far - infrared transmission, nbn, superconducting film, vortices, terahertz waves, parallel magnetic field 74.25.gz, 74.25.ha, 74.78.-w
grb 121027a is un - usual with its extremely long - lasting, energetic x - ray flares.   the total energy release in x - ray flares is about one order of magnitude higher than prompt @xmath0-rays, making it special from most long grbs.   we show that while the prompt gamma - ray emission satisfies the empirical @xmath1 relation of typical long grbs, the x - ray flares, whose spectra can be fit with a cutoff - power - law model with well - constrained @xmath2, significantly deviate from such a relation.   nonetheless, a time - resolved spectral analysis of x - ray flares suggest that the x - ray emission is consistent with the @xmath3 relation of long grbs.   we constrain the minimum lorentz factor of the x - ray flares to be @xmath4, which is consistent with the @xmath5 relation.   our results imply that prompt @xmath0-ray emission and late x - ray flares share the similar radiation mechanism, but originate from the outflows with different lorentz factors.   we search for similar grbs from the _ swift _ grb archives, and find that the @xmath6 grb 050904 is a carbon copy of grb 121027a.   the long - lasting, energetic x - ray flares in these grbs demand significant accretion at late times, which point towards a large - radius progenitor star.
as part of a large survey of halo and thick disc stars, we found one halo star, hd 106038, exceptionally overabundant in beryllium. in spite of its low metallicity,  = @xmath01.26  , the star has log(be / h ) = @xmath010.60, which is similar to the solar meteoritic abundance, log(be / h ) = @xmath010.58.   this abundance is more than ten times higher the abundance of stars with similar metallicity and can not be explained by models of chemical evolution of the galaxy that include the standard theory of cosmic - ray spallation.   no other halo star exhibiting such a beryllium overabundance is known.   in addition, overabundances of li, si, ni, y, and ba are also observed.   we suggest that all these chemical peculiarities, but the ba abundance, can be simultaneously explained if the star was formed in the vicinity of a hypernova.       stars : abundances  stars : chemically peculiar  stars : individual : hd 106038
we propose a dissipative method to prepare the ground state of the isotropic xy spin hamiltonian in a transverse field.   our model consists of a spin chain with nearest - neighbour interactions and an additional collective coupling of the spins to a damped harmonic oscillator.   the latter provides an effective environment with a lorentzian spectral density and can be used to drive the chain asymptotically towards its multipartite - entangled ground state at a rate that depends on the degree of non - markovianity of the evolution.   we also present a detailed proposal for the experimental implementation with a chain of trapped ions.   the protocol does not require individual addressing, concatenated pulses, or multi - particle jump operators, and is capable of generating the desired target state in small ion chains with very high fidelities.
we analyze a 1-d ring structure composed of many two - level systems, in the limit where only one excitation is present.   the two - level systems are coupled to a common environment, where the excitation can be lost, which induces super and subradiant behavior, an example of cooperative quantum coherent effect.   we consider time - independent random fluctuations of the excitation energies.   this static disorder, also called inhomogeneous broadening in literature, induces anderson localization and is able to quench superradiance.   we identify two different regimes : @xmath0 weak opening, in which superradiance is quenched at the same critical disorder at which the states of the closed system localize ; @xmath1 strong opening, with a critical disorder strength proportional to both the system size and the degree of opening, displaying robustness of cooperativity to disorder.   relevance to photosynthetic complexes is discussed.
we propose an experimental scheme to cool and measure the three - dimensional ( 3d ) motion of an optically trapped nanosphere in a cavity. driven by three lasers on tem00, tem01, and tem10 modes, a single cavity can cool a trapped nanosphere to the quantum ground states in all three dimensions under the resolved - sideband condition. our scheme can also detect an individual collision between a single molecule and a cooled nanosphere efficiently. such ability can be used to measure the mass of molecules and the surface temperature of the nanosphere.   we also discuss the heating induced by the intensity fluctuation, pointing instability, and the phase noise of lasers, and justify the feasibility of our scheme under current experimental conditions.
we investigate the dynamics of the recently proposed model of assisted inflation. in this model   an arbitrary number of scalar fields with exponential potentials evolve towards an inflationary scaling solution, even if each of the individual potentials is too steep to support inflation on its own. by choosing an appropriate rotation in field space we can write down explicitly the potential for the weighted mean field along the scaling solution and for fields orthogonal to it.   this demonstrates that the potential has a global minimum along the scaling solution.   we show that the potential close to this attractor in the rotated field space is analogous to a hybrid inflation model, but with the vacuum energy having an exponential dependence upon a dilaton field.   we present analytic solutions describing homogeneous and inhomogeneous perturbations about the attractor solution without resorting to slow - roll approximations.   we discuss the curvature and isocurvature perturbation spectra produced from vacuum fluctuations during assisted inflation.
the color - magnitude diagrams of @xmath0 stars obtained for 12 fields across the galactic bulge with the ogle project reveal a well - defined population of bulge red clump giants.   we find that the distributions of the apparent magnitudes of the red clump stars are systematically fainter when moving towards lower galactic @xmath1 fields.   the most plausible explanation of this distinct trend is that the galactic bulge is a bar, whose nearest end lies at positive galactic longitude.   we model this galactic bar by fitting for all fields the observed luminosity functions in the red clump region of the color - magnitude diagram.   we find that almost regardless of the analytical function used to describe the 3-d stars distribution of the galactic bar, the resulting models have the major axis inclined to the line of sight by @xmath2, with axis ratios corresponding to @xmath3.   this puts a strong constraint on the possible range of the galactic bar models.   gravitational microlensing can provide us with additional constrains on the structure of the galactic bar.
despite the fact that the fundamental physical laws are symmetric in time, most observed processes do not show this symmetry.   especially the phenomenon of decay seems to involve a kind of irreversibility that makes the definition of a microscopic arrow of time possible.   such an intrinsic irreversibility is incorporated within the rigged hilbert space quantum mechanics of the brussels school, contrasting to the statements of standard quantum mechanics. as shown in this paper,   the formalism bears significant advantages in the description of decaying systems, however the breaking of time symmetry can be avoided.    2
we study a modified ramsey spectroscopy technique employing slowly decaying states for quantum metrology applications using dense ensembles.   while closely positioned atoms exhibit superradiant collective decay and dipole - dipole induced frequency shifts, recent results [ ostermann, ritsch and genes, phys.   rev.   lett. * 111 *, 123601 ( 2013 ) ] suggest the possibility to suppress such detrimental effects and achieve an even better scaling of the frequency sensitivity with interrogation time than for noninteracting particles. here   we present an in - depth analysis of this protected subspace ramsey technique using improved analytical modeling and numerical simulations including larger 3d samples.   surprisingly we find that using sub - radiant states of @xmath0 particles to encode the atomic coherence yields a scaling of the optimal sensitivity better than @xmath1.   applied to ultracold atoms in 3d optical lattices we predict a precision beyond the single atom linewidth.
we consider estimating the parameter associated with the qubit depolarizing channel when the available initial states that might be employed are mixed.   we use quantum fisher information as a measure of the accuracy of estimation to compare protocols which use collections of qubits in product states to one in which the qubits are in a correlated state.   we show that, for certain parameter values and initial states, the correlated state protocol can yield a greater accuracy per channel invocation than the product state protocols.   we show that, for some parameters and initial states, using more than two qubits and channel invocations is advantageous.   these results stand in contrast to the known optimal case that uses pure initial states and a single channel invocation on a pair of entangled qubits.
we investigate correlations between the direction of the optical linear polarization and the orientation of the host galaxy / extended emission for type1 and type2 radio - loud and radio - quiet quasars.   we have used high resolution hubble space telescope data and a deconvolution process to obtain a good determination of the host galaxy / extended emission ( ee ) position angle. with these new measurements and a compilation of data from the literature  , we find a significant correlation, different for type1 and type2 objects, between the linear polarization position angle and the orientation of the ee, suggesting scattering by an extended uv / blue region in both types of objects.   our observations support the extension of the unification model to the higher luminosity agns like the quasars, assuming a two component scattering model.
among all the asteroid dynamical groups, centaurs have the highest fraction of objects moving in retrograde orbits. the distribution in absolute magnitude, @xmath0, of known retrograde centaurs with semi - major axes in the range 634 au exhibits a remarkable trend : 10% have @xmath1 10 mag, the rest have @xmath2 12 mag.   the largest objects, namely ( 342842 ) 2008  yb@xmath3, 2011  mm@xmath4 and 2013  lu@xmath5, move in almost polar, very eccentric paths ; their nodal points are currently located near perihelion and aphelion. in the group of retrograde centaurs, they are obvious outliers both in terms of dynamics and size. here, we show that these objects are also trapped in retrograde resonances that make them unstable.   asteroid 2013  lu@xmath5, the largest, is a candidate transient co - orbital to uranus and it may be a recent visitor from the trans - neptunian region.   asteroids 342842 and 2011  mm@xmath4 are temporarily submitted to various high - order retrograde resonances with the jovian planets but 342842 may be ejected towards the trans - neptunian region within the next few hundred kyr.   asteroid 2011  mm@xmath4 is far more stable.   our analysis shows that the large retrograde centaurs form an heterogeneous group that may include objects from various sources.   asteroid 2011  mm@xmath4 could be a visitor from the oort cloud but an origin in a relatively stable closer reservoir can not be ruled out.   minor bodies like 2011  mm@xmath4 may represent the remnants of the primordial planetesimals and signal the size threshold for catastrophic collisions in the early solar system.
the paper presents instructive interdisciplinary applications of constrained mechanics calculus in economics on a level appropriate for the undergraduate physics education.   the aim of the paper is :    1.   to meet the demand for illustrative examples suitable for presenting the background of the highly expanding research field of econophysics even on the undergraduate level and 2.   to enable the students to understand deeper the principles and methods routinely used in mechanics by looking at the well known methodology from the different perspective of economics.   two constrained dynamic economic problems are presented using the economic terminology in an intuitive way.   first, the phillips model of business cycle is presented as a system of forced oscillations and the general problem of two interacting economies is solved by the nonholonomic dynamics approach.   second, the cass - koopmans - ramsey model of economical growth is solved as a variational problem with a velocity dependent constraint using the vakonomic approach.   the specifics of the solution interpretation in economics compared to mechanics is discussed in detail, a discussion of the nonholonomic and vakonomic approaches to constrained problems in mechanics and economics is provided and an economic interpretation of the lagrange multipliers ( possibly surprising for the students of physics ) is carefully explained. the paper can be used by the undergraduate students of physics interested in interdisciplinary physics applications to get in touch with current scientific approach to economics based on a physical background or by university teachers as an attractive supplement to the classical mechanics lessons.
we use symbolic dynamics to study discrete - time dynamical systems with multiple time delays.   we exploit the concept of avoiding sets, which arise from specific non - generating partitions of the phase space and restrict the occurrence of certain symbol sequences related to the characteristics of the dynamics. in particular, we show that the resulting forbidden sequences are closely related to the time delays in the system.   we present two applications to coupled map lattices, namely ( 1 ) detecting synchronization and ( 2 ) determining unknown values of the transmission delays in networks with possibly directed and weighted connections and measurement noise.   the method is applicable to multi - dimensional as well as set - valued maps, and to networks with time - varying delays and connection structure.    _   preprint_. for final version, see : _ physics letters a _ * 375 * ( 2010 ) 130135.   + http://dx.doi.org/10.1016/j.physleta.2010.10.044
we present a detailed finite - temperature hartree - fock - bogoliubov ( hfb ) treatment of the two - dimensional trapped bose gas.   we highlight the numerical methods required to obtain solutions to the hfb equations within the popov approximation, the derivation of which we outline.   this method has previously been applied successfully to the three - dimensional case and we focus on the unique features of the system which are due to its reduced dimensionality.   these can be found in the spectrum of low - lying excitations and in the coherence properties.   we calculate the bragg response and the coherence length within the condensate in analogy with experiments performed in the quasi - one - dimensional regime [ richard _ et al.   _, phys.   rev.   lett.  * 91 *, 010405 ( 2003 ) ] and compare to results calculated for the one - dimensional case.   we then make predictions for the experimental observation of the quasicondensate phase via bragg spectroscopy in the quasi - two - dimensional regime.
the lhcb collaboration has recently reported on some anomalies in @xmath0 transitions.   in addition to discrepancies with the standard model ( sm ) predictions in some angular observables and branching ratios, an intriguing hint for lepton universality violation was found.   here we propose a simple model that extends the sm with a dark sector charged under an additional @xmath1 gauge symmetry.   the spontaneous breaking of this symmetry gives rise to a massive @xmath2 boson, which communicates the sm particles with a valid dark matter candidate, while solving the @xmath3 anomalies with contributions to the relevant observables.
we give a brief account of the recent progresses in super yang - mills theories based in particular on the application of nekrasov s instanton technology to the case of @xmath0 supersymmetry.   we have developed a first - principle formalism from which any chiral observable in the theory can be computed, including in strongly coupled confining vacua.   the correlators are first expressed in terms of some external variables as sums over colored partitions.   the external variables are then fixed to their physical values by extremizing the microscopic quantum superpotential.   remarquably, the results can be shown to coincide with the dijkgraaf - vafa matrix model approach, which uses a totally different mathematical framework.   these results clarify many important properties of @xmath0 theories, related in particular to generalized konishi anomaly equations and to veneziano - yankielowicz terms in the glueball superpotentials.   the proof of the equivalence between the formalisms based on colored partitions and on matrices is also a proof of the open / closed string duality in the chiral sector of the theories.
the temperature dependence of the casimir effect for the radiation field confined between two conducting plates is analysed.   the casimir energy is shown to decline exponentially with temperature while the casimir entropy which is defined in the text is shown to approach a limit which depends only on the geometry of the constraining plates.   the results are discussed in terms of the relation between the bose distribution function and the equipartition theorem - a relation based on a study by einstein and stern circa 1913.   -0.8 in -0.2 in 23.5 cm
the time evolution of magnons subject to a time - dependent microwave field is usually described within the so - called `` s - theory '', where kinetic equations for the distribution function are obtained within the time - dependent hartree - fock approximation.   to explain the recent observation of `` bose - einstein condensation of magnons '' in an external microwave field [ demokritov _ et al.   _, nature * 443 *, 430 ( 2006 ) ], we extend the `` s - theory '' to include the gross - pitaevskii equation for the time - dependent expectation values of the magnon creation and annihilation operators.   we explicitly solve the resulting coupled equations within a simple approximation where only a single condensed mode is retained.   we also re - examine the usual derivation of an effective boson model from a realistic spin model for yttrium - iron garnet films and argue that in the parallel pumping geometry ( where both the static and the time - dependent magnetic field are parallel to the macroscopic magnetization ) the time - dependent zeemann energy can not give rise to magnon condensation.   = 10000 = 1
we present a new method of image cleaning for imaging atmospheric cherenkov telescopes.   the method is based on the utilization of wavelets to identify noise pixels in images of gamma - ray and hadronic induced air showers.   this method selects more signal pixels with cherenkov photons than traditional image processing techniques.   in addition, the method is equally efficient at rejecting pixels with noise alone.   the inclusion of more signal pixels in an image of an air shower allows for a more accurate reconstruction, especially at lower gamma - ray energies that produce low levels of light.   we present the results of monte carlo simulations of gamma - ray and hadronic air showers which show improved angular resolution using this cleaning procedure.   data from the whipple observatory s 10-m telescope are utilized to show the efficacy of the method for extracting a gamma - ray signal from the background of hadronic generated images.   gamma - ray astronomy ; atmospheric cherenkov technique ; wavelets
quandle 2-cocycles define invariants of classical and virtual knots, and extensions of quandles.   we show that the quandle 2-cocycle invariant with respect to a non - trivial @xmath0-cocycle is constant, or takes some other restricted form, for classical knots when the corresponding extensions satisfy certain algebraic conditions. in particular,   if an abelian extension is a conjugation quandle, then the corresponding cocycle invariant is constant.   specific examples are presented from the list of connected quandles of order less than 48.   relations among various quandle epimorphisms involved are also examined. + key words : quandles, quandle cocycle invariants, abelian extensions of quandles + msc : 57m25
we study the steady state of the abelian sandpile models with stochastic toppling rules. the particle addition operators commute with each other, but in general these operators need not be diagonalizable.   we use their abelian algebra to determine their eigenvalues, and the jordan block structure.   these are then used to determine the probability of different configurations in the steady state.   we illustrate this procedure by explicitly determining the numerically exact steady state for a one dimensional example, for systems of size @xmath0, and also study the density profile in the steady state.
observation of the h@xmath0o megamaser galaxy ic  2560 with the chandra observatory reveals a complex spectrum composed of soft x - ray emission due to multi - temperature thermal plasma, and a hard continuum with strong emission lines.   the continuum is most likely a compton reflection ( reprocessing ) of primary emission that is completely absorbed at least up to 7 kev.   the lines can be identified with fluorescence from si, s and fe in the lowest ionization stages.   the equivalent widths of the si and s lines are broadly compatible with those anticipated for reprocessing by optically thick cold plasma of solar abundances, while the large equivalent width of the fe line requires some overabundance of iron. a contribution to the line from a transmitted component   can not be ruled out, but the limits on the strength of the compton shoulder make it less likely. from the bolometric luminosity of the nuclear region, we infer that the source radiates at 1 - 10% of its eddington luminosity, for an adopted central mass of @xmath1 m@xmath2.   the overall spectrum is consistent with the hypotheses that the central engines powering the detected megamsers in accretion disks are obscured from direct view by the associated accretion disk material itself, and that there is a correlation between the occurrence of megamaser emission and compton - thick absorption columns.   for the 11 known galaxies with both column density measurements and maser emission believed to arise from accretion disks, eight agn are compton thick.
quantum confinement of the perpendicular motion of electrons in single - crystalline metallic superconducting nanofilms splits the conduction band into a series of single - electron subbands.   a distinctive feature of such a nanoscale multi - band superconductor is that the energetic position of each subband can vary significantly with changing nanofilm thickness, substrate material, protection cover and other details of the fabrication process.   it can occur that the bottom of one of the available subbands is situated in the vicinity of the fermi level.   we demonstrate that the character of the superconducting pairing in such a subband changes dramatically and exhibits a clear molecule - like trend, which is very similar to the well - known crossover from the bardeen - cooper - schrieffer regime to bose - einstein condensation ( bcs - bec ) observed in trapped ultracold fermions. for @xmath0 nanofilms with thickness of @xmath1 and @xmath2 monolayers ( @xmath3 )   this will lead to a spectacular scenario : up to half of all the cooper pairs nearly collapse, shrinking in the lateral size ( parallel to the nanofilm ) down to a few nanometers. as a result,   the superconducting condensate will be a coherent mixture of almost molecule - like fermionic pairs with ordinary, extended cooper pairs.
universal quantum cloning machines ( uqcms ), sometimes called quantum cloners, generate many outputs with identical density matrices, with as close a resemblance to the input state as is allowed by the basic principles of quantum mechanics.   any experimental realization of a quantum cloner has to cope with the effects of decoherence which terminate the coherent evolution demanded by a uqcm.   we examine how many clones can be generated within a decoherence time.   we compare the time that a quantum cloner implemented with trapped ions requires to produce @xmath0 copies from @xmath1 identical pure state inputs and the decoherence time during which the probability of spontaneous emission becomes non - negligible.   we find a method to construct an @xmath2 cloning circuit, and estimate the number of elementary logic gates required.   it turns out that our circuit is highly vulnerable to spontaneous emission as the number of gates in the circuit is exponential with respect to the number of qubits involved.
we explore the impact of fermi - like acceleration of lyman - alpha ( ly@xmath0 ) photons across shock fronts on the observed ly@xmath0spectral line shape.   we first confirm the result of neufeld & mckee ( 1988 ) that this mechanism gives rise to extended blue wings which may have been observed in some radio galaxies.   our monte - carlo radiative transfer calculations further show that in a minor modification of the shell - model, in which we add an additional static shell of hydrogen, this process can naturally explain the small blue bumps observed in a subset of ly@xmath0 emitting galaxies, which have been difficult to explain with conventional shell - models.   blue bumps can be produced with an additional column density of static hydrogen as small as @xmath1, and typically occur at roughly the outflow velocity of the shell. in our model   the spectra of so - called ` blue - bump objects'might reflect an evolutionary stage in which the outflows regulating the escape of ly@xmath0 photons are still engulfed within a static interstellar medium.       line : profiles  radiative transfer  shock waves  methods : numerical  galaxies : star formation  ism : jets and outflows
a double - crystal diamond ( 111 ) monochromator recently implemented at the linac coherent light source ( lcls ) enables splitting of the primary x - ray beam into a pink ( transmitted ) and a monochromatic ( reflected ) branch. the first monochromator crystal with a thickness of @xmath0  100  @xmath1 m provides sufficient x - ray transmittance to enable simultaneous operation of two beamlines.   here we report on the design, fabrication, and x - ray characterization of the first and second ( 300-@xmath1m - thick ) crystals utilized in the monochromator and the optical assemblies holding these crystals.   each crystal plate has a region of about 5  @xmath2  2  mm@xmath3 with low defect concentration, sufficient for use in x - ray optics at the lcls.   the optical assemblies holding the crystals were designed to provide mounting on a rigid substrate and to minimize mounting - induced crystal strain.   the induced strain was evaluated using double - crystal x - ray topography and was found to be small over the 5  @xmath2  2  mm@xmath3 working regions of the crystals.
a langevin process diffusing in a periodic potential landscape has a time dependent diffusion constant which means that its average mean squared displacement ( msd ) only becomes linear at late times.   the long time, or effective diffusion constant, can be estimated from the slope of a linear fit of the msd at late times.   due to the cross over between a short time microscopic diffusion constant, which is independent of the potential, to the effective late time diffusion constant, a linear fit of the msd will not in general pass through the origin and will have a non - zero constant term. here   we address how to compute the constant term and provide explicit results for brownian particles in one dimension in periodic potentials.   we show that the constant is always positive and that at low temperatures it depends on the curvature of the minimum of the potential. for comparison   we also consider the same question for the simpler problem of a symmetric continuous time random walk in discrete space. here   the constant can be positive or negative and can be used to determine the variance of the hopping time distribution.
we prove that the sonic surface of axisymmetric meridional stationary flows is always attached to the accretor, however small, if the adiabatic index of the gas is @xmath0.   + using local expansions near a point - like accretor, we extend bondi s classification of spherically symmetric flows to axisymmetric flows, introducing the possibility of angular sectors reached by no flow lines, and singular directions of infinite mass flux, in addition to the angular regions of subsonic and supersonic accretion. for @xmath1, we show the impossibility of subsonic accretion onto a point  like accretor when the entropy of the flow is not uniform.   the special case @xmath0 is treated separately.   + we analyse the influence of the adiabatic index and mach number of the flow at infinity on the mass accretion rate of shocked spherical flows.   we propose an interpolation formula for the mass accretion rate of axisymmetric flows as a function of the mach number and the adiabatic index, in the range @xmath2.   # 1 # 1 by # 2 ( # 3 )    to # 2   ''' ''    width # 1 height 0pt depth 0pt
self - steepening of optical pulses arises due the dispersive contribution of the @xmath0 kerr nonlinearity. in typical structures   this response is on the order of a few femtoseconds with a fixed frequency response.   in contrast, the effective @xmath1 kerr nonlinearity in photonic crystal waveguides ( phcwgs ) is largely determined by the geometrical parameters of the structure and is consequently tunable over a wide range.   here we show self - steepening based on group - velocity ( group - index ) modulation for the first time, giving rise to a new physical mechanism for generating this effect.   further, we demonstrate that periodic media such as phcwgs can exhibit self - steepening coefficients two orders of magnitude larger than typical systems. at these magnitudes   the self - steepening strongly affects the nonlinear pulse dynamics even for picosecond pulses. due to interaction with additional higher - order nonlinearities in the semiconductor materials under consideration  , we employ a generalized nonlinear schrdinger equation numerical model to describe the impact of self - steepening on the temporal and spectral properties of the optical pulses in practical systems, including new figures of merit.   these results provide a theoretical description for recent experimental results presented in [ _ scientific reports 3, 1100 ( 2013 ) _ and _ phys.   rev.   a 87, 041802 ( 2013 ) _ ].   more generally, these observations apply to all periodic media due to the rapid group - velocity variation characteristic of these structures.
we report the discovery of a young and energetic pulsar in the parkes multibeam survey of the galactic plane.   has a rotation period of @xmath0ms and period derivative of @xmath1, implying a characteristic age of 21kyr and spin - down luminosity of @xmath2ergs@xmath3.   the pulsar is located just outside, and possibly interacting with, the shell supernova remnant.   archival x - ray data show a source near the pulsar position which is consistent with emission from a pulsar wind nebula.   the pulsar is also located inside the error box of the unidentified  source, for which it represents a plausible counterpart.
we present squeezing and anti - squeezing spectra of the output from a degenerate optical parametric oscillator ( opo ) network arranged in different coherent quantum feedback configurations.   one opo serves as a quantum plant, the other as a quantum controller.   the addition of coherent feedback enables shaping of the output squeezing spectrum of the plant, and is found to be capable of pushing the frequency of maximum squeezing away from the optical driving frequency and broadening the spectrum over a wider frequency band.   the experimental results are in excellent agreement with the developed theory, and illustrate the use of coherent quantum feedback to engineer the quantum - optical properties of the plant opo output.
we report on the results of spectral fits made to a _ nustar _   observation of the black hole grs  1915@xmath0105 in a `` plateau '' state.   this state is of special interest because it is similar to the `` low / hard '' state seen in other black holes, especially in that compact, steady jets are launched in this phase.   the 379  kev bandpass of _ nustar _, and its ability to obtain moderate   resolution spectra free from distortions such as photon pile - up, are extremely well suited to studies of disk reflection in x - ray binaries. in only 15  ks of net exposure, an extraordinarily sensitive spectrum of grs 1915@xmath0105 was measured across the full bandpass.   ionized reflection from a disk around a rapidly  spinning black hole is clearly required to fit the spectra ; even hybrid comptonization models including ionized reflection from a disk around a schwarzschild black hole proved inadequate.   a spin parameter of @xmath1 ( @xmath2 statistical error ) is measured via the best   fit model ; low spins are ruled out at a high level of confidence.   this result suggests that jets can be launched from a disk extending to the innermost stable circular orbit. a very steep inner disk emissivity profile is also measured, consistent with models of compact coronae above kerr black holes.   these results support an emerging association between the hard x - ray corona and the base of the relativistic jet.
we perform a detailed comparison of magnetotunneling in conventional low-@xmath0 nb / alalox / nb junctions with that in slightly overdoped bi@xmath1pb@xmath2sr@xmath3cacu@xmath3o@xmath4  intrinsic josephson junctions and with microscopic calculations.   it is found that both types of junctions behave in a qualitatively similar way.   both magnetic field and temperature suppress superconductivity in the state - conserving manner.   this leads to the characteristic sign - change of tunneling magnetoresistance from the negative at the sub - gap to the positive at the sum - gap bias.   we derived theoretically and verified experimentally scaling laws of magnetotunneling characteristics and employ them for accurate extraction of the upper critical field @xmath5. for nb an extended region of surface superconductivity at @xmath6   is observed.   the parameters of bi(pb)-2212 were obtained from self - consistent analysis of magnetotunneling data at different levels of bias, dissipation powers and for different mesa sizes, which precludes the influence of self - heating.   it is found that @xmath7 for bi(pb)-2212 is @xmath8 t and decreases significantly at @xmath9.   the amplitude of sub - gap magnetoresistance is suppressed exponentially at @xmath10, but remains negative, although very small, above @xmath0.   this may indicate existence of an extended fluctuation region, which, however, does not destroy the general second - order type of the phase transition at @xmath0.
we consider unstable attractors ; milnor attractors @xmath0 such that, for some neighbourhood @xmath1 of @xmath0, almost all initial conditions leave @xmath1.   previous research strongly suggests that unstable attractors exist and even occur robustly ( i.e.  for open sets of parameter values ) in a system modelling biological phenomena, namely in globally coupled oscillators with delayed pulse interactions.    in the first part of this paper we give a rigorous definition of unstable attractors for general dynamical systems.   we classify unstable attractors into two types, depending on whether or not there is a neighbourhood of the attractor that intersects the basin in a set of positive measure.   we give examples of both types of unstable attractor ; these examples have non - invertible dynamics that collapse certain open sets onto stable manifolds of saddle orbits.   in the second part we give the first rigorous demonstration of existence and robust occurrence of unstable attractors in a network of oscillators with delayed pulse coupling.   although such systems are technically hybrid systems of delay differential equations with discontinuous ` firing'events, we show that their dynamics reduces to a finite dimensional hybrid system system after a finite time and hence we can discuss milnor attractors for this reduced finite dimensional system.   we prove that for an open set of phase resetting functions there are saddle periodic orbits that are unstable attractors.   * keywords * pulse - coupled oscillator, heteroclinic cycle, global coupling, hybrid system, delay, neural network.    *   pacs * 05.45.-a ; 87.10.+e
the effects of both elliptical shape and stage of emergence of the coronal loop on the resonant absorption of standing kink oscillations are studied. to do so, a typical coronal loop is modeled as a zero - beta longitudinally stratified cylindrical magnetic flux tube.   we developed the connection formulae for the resonant absorption of standing transversal oscillations of a coronal loop with an elliptical shape, at various stages of its emergence. using the connection formulae,   the dispersion relation is derived and solved numerically to obtain the frequencies and damping rates of the fundamental and first - overtone kink modes.   our numerical results show that both the elliptical shape and stage of emergence of the loop alter the frequencies and damping rates of the tube as well as the ratio of frequencies of the fundamental and its first - overtone modes. however, the ratio of the oscillation frequency to the damping rate is not affected by the tube shape and stage of its emergence and also is independent of the density stratification parameter.   = 16truecm = 23truecm = -1.3truecm = -2truecm = 1.20 cm = 1.60 cm    _ key words : _ sun : corona  sun : magnetic fields  sun : oscillations
we present the first search for the decay @xmath0 to test the four - quark content of the @xmath1 and the @xmath2-@xmath3 mixing model for this decay.   we use @xmath4 @xmath5 of @xmath6 collision data collected at a center - of - mass energy of 4170 mev.   we find no evidence of a signal, and set an upper limit on the branching fraction of @xmath70.20% at the 90% confidence level.
we introduce and study random bipartite networks with hidden variables.   nodes in these networks are characterized by hidden variables which control the appearance of links between node pairs.   we derive analytic expressions for the degree distribution, degree correlations, the distribution of the number of common neighbors, and the bipartite clustering coefficient in these networks.   we also establish the relationship between degrees of nodes in original bipartite networks and in their unipartite projections.   we further demonstrate how hidden variable formalism can be applied to analyze topological properties of networks in certain bipartite network models, and verify our analytical results in numerical simulations.
we examine the brightness of the cosmic radio background ( crb ) by comparing the contribution from individual source counts to absolute measurements.   we use a compilation of radio counts to estimate the contribution of detected sources to the crb in several different frequency bands. using a monte carlo markov chain technique  , we estimate the brightness values and uncertainties, paying attention to various sources of systematic error. at @xmath0   = @xmath1mhz, @xmath2mhz, @xmath3mhz, @xmath4mhz, @xmath5ghz, @xmath6ghz, and @xmath7ghz our calculated contributions to the background sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032, 0.0059 k, respectively.   we then compare our results to absolute measurements from the arcade 2 experiment.   if the arcade 2 measurements are correct and come from sources, then there must be an additional population of radio galaxies, fainter than where current data are probing. more specifically  , the euclidean - normalized counts at 1.4 ghz have to have an additional bump below about 10 @xmath8jy.       galaxies : statistics  radio continuum : galaxies  diffuse radiation  source counts  methods : monte carlo markov chain
we propose a new method to study transverse flow effects in relativistic nuclear collisions by fourier analysis of the azimuthal distribution on an event - by - event basis in relatively narrow rapidity windows.   the distributions of fourier coefficients provide direct information on the magnitude and type of flow.   directivity and two dimensional sphericity tensor, widely used to analyze flow, emerge naturally in our approach, since they correspond to the distributions of the first and second harmonic coefficients, respectively.   the role of finite particle fluctuations and particle correlations is discussed.
i highlight results from _ chandra _ observations of nearby galaxies, including the milky way.   these observations have offered insights into old mysteries and indications of new high energy astrophysical phenomena and processes that are yet to be understood.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we have computed theoretical models of circumstellar disks for the classical be stars @xmath0 dra, @xmath1 psc, and @xmath2 cyg.   models were constructed using a non - lte radiative transfer code developed by @xcite which incorporates a number of improvements over previous treatments of the disk thermal structure, including a realistic chemical composition.   our models are constrained by direct comparison with long baseline optical interferometric observations of the h@xmath3 emitting regions and by contemporaneous h@xmath3 line profiles.   detailed comparisons of our predictions with h@xmath3 interferometry and spectroscopy place very tight constraints on the density distributions for these circumstellar disks.
the hard x - ray bursts observed during both major outbursts of the bursting pulsar ( gro  j1744@xmath028 ) show pulsations near the neutron star spin frequency with an enhanced amplitude relative to that of the persistent emission.   consistent with previous work, we find that the pulsations within bursts lag behind their expected arrival times based upon the persistent pulsar ephemeris. for an ensemble of 1293 bursts recorded with the burst and transient source experiment,   the average burst pulse time delay ( @xmath1t@xmath2 ) is 61.0  @xmath3  0.8 ms in the 25  50 kev energy range and 72  @xmath3  5 ms in the 50  100 kev band.   the residual time delay ( @xmath1t@xmath4 ) from 10 to 240 s following the start of the burst is 18.1  @xmath3  0.7 ms ( 25  50 kev )  . a significant correlation of the average burst time delay with burst peak flux is found.   our results are consistent with the model of the pulse time lags presented by miller ( 1996 ).
j/@xmath0 suppression induced by color screening of its constituent quarks was proposed 26 years ago as a signature of the formation of a quark gluon plasma in heavy - ion collisions.   recent results from alice in pb - pb collisions exhibit a smaller suppression with respect to previous measurements at the sps and rhic.   the study of azimuthal anisotropy in particle production gives information on the collective hydrodynamic expansion at the early stage of the fireball, where the matter created in high - energy nuclear collisions is expected to be in a deconfined state.   in particular, j/@xmath0 elliptic flow @xmath1 is important to test the degree of thermalization of heavy quarks.   together with the production yields, the elliptic flow is a powerful observable to address the question of suppression and regeneration of j/@xmath0 in qgp.   we present the first inclusive j/@xmath0 elliptic flow measurement performed with the muon spectrometer of alice, in pb - pb collisions, at forward rapidity. integrated and @xmath2-differential @xmath1 results are presented and a comparison with recent star results and with a parton transport model is also performed.   qgp, alice, elliptic flow, quarkonia, suppression, regeneration
we present new radio and optical observations of the colliding - wind system wr146 aimed at understanding the nature of the companion to the wolf - rayet star and the collision of their winds.   the radio observations reveal emission from three components : the wr stellar wind, the non - thermal wind - wind interaction region and, for the first time, the stellar wind of the ob companion.   this provides the unique possibility of determining the mass - loss rate and terminal wind velocity ratios of the two winds, independent of distance. respectively, these ratios are determined to be @xmath0 and @xmath1 for the ob - companion star relative to the wr star.   a new optical spectrum indicates that the system is more luminous than had been believed previously.   we deduce that the `` companion '' can not be a single, low luminosity o8 star as previously suggested, but is either a high luminosity o8 star, or possibly an o8+wc binary system.   -0.5 in    stars : individual : wr146  stars : wolf - rayet  radio continuum : stars
we consider gauged q - balls in the gravity - mediation - type model in the affleck - dine mechanism, which is described by the potential @xmath0 $ ] with @xmath1. in many models of gauged q - balls, which were studied in the literature,   there are upper limits for charge and size of q - balls due to repulsive coulomb force. in the present model, by contrast  , our numerical calculation strongly suggests that stable solutions with any amount of charge and size exist.   as the electric charge @xmath2 increases, the field configuration of the scalar field becomes shell - like ; because the charge is concentrated on the surface, the coulomb force does not destroy the q - ball configuration.   these properties are analogous to those in the v - shaped model, which was studied by arod and lis.   we also find that for each @xmath3 there is another sequence of unstable solutions, which is separated from the other sequence of the stable solutions.   as @xmath4 increases, the two sequences approach ; eventually at some point in @xmath5, the  recombination " of the two sequences takes place.
we have analyzed @xmath0600 ks of _ rossi x - ray timing explorer _ data of the neutron star low - mass x - ray binary and z source gx 17 + 2.   a study was performed of the properties of the noise components and quasi - periodic oscillations ( qpos ) as a function of the broad - band spectral properties, with the main goal to study the relation between the frequencies of the horizontal branch ( hbo ) and upper khz qpos.   it was found that when the upper khz qpo frequency is below 1030 hz these frequencies correlate, whereas above 1030 hz they anti - correlate.   gx 17 + 2 is the first source in which this is observed.   we also found that the frequency difference of the high frequency qpos was not constant and that the quality factors ( q values ) of the hbo, its second harmonic, and the khz qpos are similar, and vary almost hand in hand by a factor of more than three  . observations of the normal branch oscillations during two type i x - ray bursts showed that their absolute amplitude decreased as the flux from the neutron star became stronger.   we discuss these and other findings in terms of models that have been proposed for these phenomena.   we also compare the behavior of gx 17 + 2 and other z sources with that of black hole sources and consider the possibility that the mass accretion rate might not be the driving force behind all spectral and variability changes.
a double quantum dot coupled to an @xmath0-wave superconductor and subject to an inhomogeneous magnetic field can host a pair of zero - energy majorana fermions when the dot properties are tuned appropriately.   here, we demonstrate the possibility to generate a fractional @xmath1 josephson effect in two such double dots tunnel - coupled to each other.   we discuss the robustness of this effect with respect to perturbations away from the special point in parameter space where the uncoupled double dots host majorana fermions.   we demonstrate the possibility to generate josephson effects with a period of @xmath2 and @xmath3 in strongly - coupled double dots.
in this paper we study efficiency of particle acceleration in the magnetospheres of stellar mass black holes. for this purpose   we consider the linearized set of the euler equation, continuity equation and poisson equation respectively. after introducing the varying relativistic centrifugal force,   we show that the charge separation undergoes the parametric instability, leading to generation of centrifugally excited langmuir waves.   it is shown that these waves, via the langmuir collapse damp by means of the landau damping, as a result energy transfers to particles accelerating them to energies of the order of @xmath0ev.
we study the equilibrium properties of a lattice - gas model of an @xmath0 catalytic reaction on a one - dimensional chain in contact with a reservoir for the particles.   the particles of species @xmath1 and @xmath2 are in thermal contact with their vapor phases acting as reservoirs, i.e., they may adsorb onto empty lattice sites and may desorb from the lattice.   if adsorbed @xmath1 and @xmath2 particles appear at neighboring lattice sites they instantaneously react and both desorb. for this model of a catalytic reaction in the adsorption - controlled limit,   we derive analytically the expression of the pressure and present exact results for the mean densities of particles and for the compressibilities of the adsorbate as function of the chemical potentials of the two species.    * equilibrium properties of a monomer - monomer catalytic reaction on a one - dimensional chain *    * g. oshanin@xmath3, m. n. popescu@xmath4, and s. dietrich@xmath4 *    _ @xmath3 laboratoire de physique thorique des liquides, + universit paris 6, 4 place jussieu, 75252 paris, france _    _ @xmath5 max - planck - institut fr metallforschung, + heisenbergstr.   3, d-70569 stuttgart, germany _    _ @xmath6 institut fr theoretische und angewandte physik, + universitt stuttgart, pfaffenwaldring 57, d-70569 stuttgart, germany _    : 05.50.+q ; 64.60.cn ; 68.43.de ; 82.65
from  narrow band observations, we identified three  emitting regions in the direction of magellanic stream iv ( ms iv ).   they consist of three parallel filaments with 2 arcmin width and 6  30 arcmin length at 12 arcmin intervals.   the mean surface brightness of them is @xmath0 erg s@xmath1 @xmath2 arcsec@xmath3. because of their low surface brightness  , the regions were not detected in previous  surveys. in  map,   the position of the filaments overlap ms, suggesting that they are parts of ms, but there also exists a local  structure.   if the filaments associate with ms, the sizes are 30 pc @xmath4 100  500 pc.   the filaments lie at the leading edge of a downstream cloud, which supports a shock heating and its propagation ( shock cascade ) model for the ionizing source.   if they are local objects, on the other hand, fossil strmgren trails of more than two stars is a possible interpretation, and the sizes would be 0.1 pc @xmath4 0.3  1.5 pc at 180 pc distance.   the positional information of the  filaments presented in this letter enables us future spectroscopic observations to clarify their nature.
the success or failure of the neutrino - transport mechanism for producing a supernova in an evolved massive star is known to be sensitive not only to the mass of the iron core that collapses, but also to the density gradient in the silicon and oxygen shells surrounding that core. here   we study the systematics of a presupernova core s `` compactness '' @xcite as a function of the mass of the star and the physics used in its calculation.   fine - meshed surveys of presupernova evolution are calculated for stars from 15 to 65 @xmath0.   the metallicity and the efficiency of semiconvection and overshoot mixing are both varied and bare carbon - oxygen cores are explored as well as full hydrogenic stars.   two different codes, kepler and mesa, are used for the study.   a complex interplay of carbon and oxygen burning, especially in shells, can cause rapid variations in the compactness for stars of very nearly the same mass. on larger scales,   the distribution of compactness with main sequence mass is found to be robustly non - monotonic, implying islands of `` explodability '', particularly around 8 to 20 @xmath0  and 25 to 30 @xmath0. the carbon - oxygen ( co ) core mass of a presupernova star is a better, though still ambiguous discriminant of its core structure than the main sequence mass.
we propose a new approach, multi - view laplacian support vector machines ( svms ), for semi - supervised learning under the multi - view scenario.   it integrates manifold regularization and multi - view regularization into the usual formulation of svms and is a natural extension of svms from supervised learning to multi - view semi - supervised learning.   the function optimization problem in a reproducing kernel hilbert space is converted to an optimization in a finite - dimensional euclidean space. after providing a theoretical bound for the generalization performance of the proposed method  , we further give a formulation of the empirical rademacher complexity which affects the bound significantly.   from this bound and the empirical rademacher complexity, we can gain insights into the roles played by different regularization terms to the generalization performance.   experimental results on synthetic and real - world data sets are presented, which validate the effectiveness of the proposed multi - view laplacian svms approach.   laplacian, multi - view learning, reproducing kernel hilbert space, semi - supervised learning, support vector machine
we computed potentials between static color sources from the six lowest representations of g@xmath0  lattice gauge theory, in numerical simulations with the wilson action on asymmetric lattices with nonperturbatively estimated values of the bare anisotropy.   we present evidence for ( approximate ) casimir scaling of the obtained intermediate string tensions.   the agreement with the casimir - scaling prediction improves by increasing the coupling @xmath1 in the weak - coupling region above the crossover observed in g@xmath0  gauge theory.   the result naturally fits into confinement models with magnetic disorder and vacuum domain structure, but may represent a challenge for other approaches.
a systematic method of calculating the dynamical conductivity tensor in a general multiband electronic model with strong boson - mediated electron - electron interactions is described.   the theory is based on the exact semiclassical expression for the coupling between valence electrons and electromagnetic fields and on the self - consistent bethe   salpeter equations for the electron - hole propagators.   the general diagrammatic perturbation expressions for the intraband and interband single - particle conductivity are determined.   the relations between the intraband bethe  salpeter equation, the quantum transport equation and the ordinary transport equation are briefly discussed within the memory - function approximation.   the effects of the lorentz dipole - dipole interactions on the dynamical conductivity of low - dimensional @xmath0 models are described in the same approximation.   such formalism proves useful in studies of different ( pseudo)gapped states of quasi - one - dimensional systems with the metal - to - insulator phase transitions and can be easily extended to underdoped two - dimensional high-@xmath1 superconductors.
we introduce a novel method to measure the masses of galaxy clusters at high redshift selected from optical and ir spitzer data via the red - sequence technique.   lyman - break galaxies are used as a well understood, high - redshift background sample allowing mass measurements of lenses at unprecedented high redshifts using weak lensing magnification. by stacking a significant number of clusters at different redshifts with average masses of @xmath0, as estimated from their richness  , we can calibrate the normalisation of the mass - richness relation. with the current data set ( area : 6 deg@xmath1 )   we detect a magnification signal at the @xmath2-@xmath3 level.   there is good agreement between the masses estimated from the richness of the clusters and the average masses estimated from magnification, albeit with large uncertainties.   we perform tests that suggest the absence of strong systematic effects and support the robustness of the measurement.   this method - when applied to larger data sets in the future - will yield an accurate calibration of the mass - observable relations at @xmath4 which will represent an invaluable input for cosmological studies using the galaxy cluster mass function and astrophysical studies of cluster formation.   furthermore this method will probably be the least expensive way to measure masses of large numbers of @xmath5 clusters detected in future ir - imaging surveys.
we propose a simple model for dirac neutrinos where the smallness of neutrino mass follows from a parameter @xmath0 whose absence enhances the symmetry of the theory. symmetry breaking is performed in a two  doublet higgs sector supplemented by a gauge singlet scalar, realizing an accidental global u(1 ) symmetry.   its spontaneous breaking at the few tev scale leads to a physical nambu   goldstone boson  the _ diracon _, denoted @xmath1  which is restricted by astrophysics and induces invisible higgs decays such as @xmath2.   the scheme provides a rich, yet very simple scenario for symmetry breaking studies at colliders such as the lhc.
anharmonic force fields and vibrational spectra of the azabenzene series ( pyridine, pyridazine, pyrimidine, pyrazine, s - triazine, 1,2,3-triazine, 1,2,4-triazine and s - tetrazine ) and benzene are obtained using density functional theory ( dft ) with the b97 - 1 exchange - correlation functional and a triple - zeta plus double polarization ( tz2p ) basis set.   overall, the fundamental frequencies computed by second - order rovibrational perturbation theory are in excellent agreement with experiment.   the resolution of the presently calculated anharmonic spectra is such that they represent an extremely useful tool for the assignment and interpretation of the experimental spectra, especially where resonances are involved.
renormalizable quartic couplings among new particles are typical of supersymmetric models  . their detection could provide a test for supersymmetry, discriminating it from other extensions of the standard model.   quartic couplings among squarks and sleptons, together with the su(3 ) gauge couplings for squarks, allow a new realization of the gluon - fusion mechanism for pair - production of sleptons at the one - loop level.   the corresponding production cross section, however, is at most of @xmath0fb for slepton and squark masses of @xmath1gev.   we then extend our investigation to the gluon - fusion production of sleptons through the exchange of higgs bosons.   the cross section is even smaller, of @xmath2fb, if the exchanged higgs boson is considerably below the slepton - pair threshold, but it is enhanced when it is resonant.   it can reach @xmath3fb for the production of sleptons of same - chirality, exceeding these values for @xmath4 s of opposite - chirality, even when chirality - mixing terms in the squark sector are vanishing.   the cross section can be further enhanced if these mixing terms are nonnegligible, providing a potentially interesting probe of the higgs sector, in particular of parameters such as @xmath5, @xmath6, and @xmath7.   +   f.  borzumati@xmath8 and k.  hagiwara@xmath9    @xmath10 _ department of physics, national taiwan university, taipei 10617, taiwan _   + @xmath11 _ kek theory division, and sokendai, tsukuba 305 - 0801, japan _
we use numerical modeling to study the features of parametric ( quasi - cherenkov ) cooperative radiation arising when an electron bunch passes through a crystal ( natural or artificial ) under the conditions of dynamical diffraction of electromagnetic waves in the presence of shot noise.   it is shown that in both laue and bragg diffraction cases, parametric radiation consists of two strong pulses : one emitted at small angles with respect to the particle velocity direction and the other emitted at large angles to it. under bragg diffraction conditions,   the intensity of parametric radiation emitted at small angles to the particle velocity direction reaches saturation at sufficiently smaller number of particles than the intensity of parametric radiation emitted at large angles. under laue diffraction conditions,   every pulse contains two strong peaks, which are associated with the emission of electromagnetic waves at the front and back ends of the bunch.   the presence of noise causes a chaotic signal in the interval between the two peaks.
we study the asymptotics of large directed graphs, constrained to have certain densities of edges and/or outward @xmath0-stars.   our models are close cousins of exponential random graph models, in which edges and certain other subgraph densities are controlled by parameters.   we find that large graphs have either uniform or bipodal structure. when edge density ( resp.   @xmath0-star density ) is fixed and @xmath0-star density ( resp.   edge density ) is controlled by a parameter, we find phase transitions corresponding to a change from uniform to bipodal structure.   when both edge and @xmath0-star density are fixed, we find only bipodal structures and no phase transition.
the description of electron - electron interactions in transport problems is both analytically and numerically difficult. here   we show that a much simpler description of electron transport in the presence of interactions can be achieved in nanoscale systems.   in particular, we show that the electron flow in nanoscale conductors can be described by navier - stokes type of equations with an effective electron viscosity, i.e., on a par with the dynamics of a viscous and compressible classical fluid. by using this hydrodynamic approach   we derive the conditions for the transition from laminar to turbulent flow in nanoscale systems and discuss possible experimental tests of our predictions.
in october 1997, the italian and dutch grb teams started a collaboration on eso optical follow - up of rapidly and accurately localized grbs. subsequently, starting april 1, 2000, this collaboration was extended to astronomers from other countries, who contributed their expertise for the creation of a consortium committed to the study of grb counterparts and host galaxies at optical and near - infrared wavelengths.   the collaboration aims at the joint exploitation of the observations taken within an eso large programme approved for the two - year period april 1, 2000 - march 31, 2002.   here we describe history and organization of this consortium, the goals of the eso large programme, and the main results obtained up to now with eso telescopes.
the wide range of uv extinction properties in the small magellanic cloud ( smc ) probably traces the effects of star formation on interstellar dust.   the swift uvot, with its three uv filters ( centred at 1800, 2200 and 2500    respectively ) and three optical filters, is an ideal instrument to map this extinction.   we present preliminary results of six - band photometry in a @xmath0 3.3  square field in the smc.   fitting the resulting optical / uv spectral distributions with a dust model, we estimate the depths of extinction for 53 stars and use this to map the distribution of dust in the observed field.   we briefly discuss the relevance of this study for star forming galaxies, including the hosts of gamma - ray bursts.
we measured the optical absorptance of superconducting nanowire single photon detectors.   we found that 200-nm - pitch, 50%-fill - factor devices had an average absorptance of 21% for normally - incident front - illumination of 1.55-@xmath0m - wavelength light polarized parallel to the nanowires, and only 10% for perpendicularly - polarized light. we also measured devices with lower fill - factors and narrower wires that were five times more sensitive to parallel - polarized photons than perpendicular - polarized photons.   we developed a numerical model that predicts the absorptance of our structures.   we also used our measurements, coupled with measurements of device detection efficiencies, to determine the probability of photon detection after an absorption event.   we found that, remarkably, absorbed parallel - polarized photons were more likely to result in detection events than perpendicular - polarized photons, and we present a hypothesis that qualitatively explains this result.   finally, we also determined the enhancement of device detection efficiency and absorptance due to the inclusion of an integrated optical cavity over a range of wavelengths ( 700 - 1700 nm ) on a number of devices, and found good agreement with our numerical model.
we present a frequency - renormalized multipolaron expansion method to explore the ground state of quantum rabi model ( qrm ).   the main idea is to take polaron as starting point to expand the ground state of qrm.   the polarons are deformed and displaced oscillator states with variationally determined frequency - renormalization and displacement parameters.   this method is an extension of the previously proposed polaron concept and the coherent state expansion used in the literature, which shows high efficiency in describing the physics of the qrm.   the proposed method is expected to be useful for solving other more complicated light - matter interaction models.
several measurements of qso - galaxy correlations have reported signals much larger than predictions of magnification by large - scale structure.   we find that the expected signal depends stronly on the properties of the foreground galaxy population.   on arcminute scales it can be either larger or smaller by a factor of two for different galaxy types in comparison with a linearly biased version of the mass distribution.   thus the resolution of some of the excess measurements may lie in examining the halo occupation properties of the galaxy population sampled by a given survey ; this is also the primary information such measurements will provide.   we use the halo model of clustering and simulations to predict the magnification induced cross - correlations and errors for forthcoming surveys. with the full sloan digital sky survey the statistical errors will be below 1 percent for the galaxy - galaxy correlations and significantly larger for qso - galaxy correlations. thus accurate constraints on parameters of the galaxy halo occupation distribution can be obtained from small scale measurements and on the bias parameter from large scales.   since the lensing induced cross - correlation measures the first moment of the halo occupation number of galaxies, these measurements can provide the basis for interpreting galaxy clustering measurements which measure the second and higher order moments.   cosmology : dark matter  cosmology : gravitational lensing  galaxies : clustering
we consider the effect of contact interaction in a prototypical quantum spin hall system of pseudo - spin-1/2 particles.   a strong effective magnetic field with opposite directions for the two spin states restricts two - dimensional particle motion to the lowest landau level.   while interaction between same - spin particles leads to incompressible correlated states at fractional filling factors as known from the fractional quantum hall effect, these states are destabilized by interactions between opposite spin particles.   exact results for two particles with opposite spin reveal a quasi - continuous spectrum of extended states with a large density of states at low energy.   this has implications for the prospects of realizing the fractional quantum spin hall effect in electronic or ultra - cold atom systems.   numerical diagonalization is used to extend the two - particle results to many bosonic particles and trapped systems.   the interplay between an external trapping potential and spin - dependent interactions is shown to open up new possibilities for engineering exotic correlated many - particle states with ultra - cold atoms.
according to quantum chromodynamics ( qcd ), matter at ultra - high densities will take the form of a color - superconducting quark liquid, in which there is a condensate of cooper pairs of quarks near the fermi surface.   i present a review of the physics of color superconductivity.   i give particular attention to the recently proposed gapless cfl ( gcfl ) phase, which has unusual properties such as quasiquarks with a near - quadratic dispersion relation, and which may well be the favored phase of quark matter in the density range relevant to compact stars.   i also discuss the effects of color superconductivity on the mass - radius relationship of compact stars, showing that one would have to fix the bag constant by other measurements in order to see the effects of color superconductivity.   an additional parameter in the quark matter equation of state connected with perturbative corrections allows quark matter to imitate nuclear matter over the relevant density range, so that hybrid stars can show a mass - radius relationship very similar to that of nuclear matter, and their masses can reach @xmath0.
the ability to post - select the outcomes of an experiment is a useful theoretical concept and experimental tool. in the context of weak measurements,   post - selection can lead to surprising results such as complex weak values outside the range of eigenvalues.   usually post - selection is realized by a projective measurement, which is hard to implement in ensemble systems such as nmr.   we demonstrate the first experiment of a weak measurement with post - selection on an nmr quantum information processor. our setup is used for measuring complex weak values and weak values outside the range of eigenvalues.   the scheme for overcoming the problem of post - selection in an ensemble quantum computer is general and can be applied to any circuit - based implementation.   this experiment paves the way for studying and exploiting post - selection and weak measurements in systems where projective measurements are hard to realize experimentally.
a model of fully developed turbulence of a _   compressible _ fluid, based on the stochastic navier - stokes equation, is studied by means of the field theoretic renormalization group.   this model has been already analyzed earlier in  [ theor.   math.   phys., * 110 *, 3 ( 1997 ) ].   its scaling properties are related to fixed points of the renormalization group equations.   our aim here is to study a possibility of existence of other scaling regimes and to analyze an opportunity of crossover between them.   this may occur in some other space dimensions than previously considered, namely in @xmath0.   a new regime arises there and then continuously moves into @xmath1.   our calculations show that there really exists an additional fixed point that governs scaling behavior.   turbulent advection of a passive scalar ( density ) field by this velocity ensemble is considered as well.   it is shown that various correlation functions of the scalar field demonstrate anomalous scaling behavior in the inertial - convective range.   the corresponding anomalous exponents, identified as scaling dimensions of certain composite fields, can be systematically calculated as a series in @xmath2 ( the exponent, connected with random force ) and @xmath3.   all calculations are performed in the leading one - loop approximation.
many different programs are the implementation of the same algorithm.   this makes the collection of algorithms a quotient of the collection of programs.   similarly, there are many different algorithms that implement the same computable function.   this makes the collection of computable functions into a quotient of the collection of algorithms.   algorithms are intermediate between programs and functions :    programs @xmath0 algorithms @xmath0 functions.   galois theory investigates the way that a subobject sits inside an object.   we investigate how a quotient object sits inside an object. by looking at the galois group of programs  , we study the the intermediate types of algorithms possible. along the way  , we formalize the intuition that one program can be substituted for another if they are the same algorithms.
this is a report on detailed modeling of young high - mass protostellar candidates during their most embedded and obscured phases.   we performed narrowband mid - infrared imaging of three candidate high - mass protostellar objects in g11.94 - 0.62, g29.96 - 0.02, and g45.07 + 0.13 at gemini observatory using the thermal - region camera and spectrograph ( t - recs ).   the sources were imaged through up to 11 narrowband filters, sampling their seds over the entire 225 @xmath0 m infrared range.   for the first time, we have fit the observed seds of massive protostars with models that take into account departures from spherical symmetry in the infalling envelopes. in this way  , we have been able to back out of the models detailed physical parameters for these earliest stages of massive stellar life.   our detailed modeling suggests that massive star formation can proceed in a way very similar to the formation of low - mass stars.
we study a heteropolymer model with random contact interactions introduced some time ago as a simplified model for proteins.   the model consists of self - avoiding walks on the simple cubic lattice, with contact interactions between nearest neighbor pairs. for each pair,   the interaction energy is an independent gaussian variable with mean value @xmath0 and variance @xmath1. for this model   the annealed approximation is expected to become exact for low disorder, at sufficiently high dimension and in the thermodynamic limit.   we show that corrections to the annealed approximation in the 3-d high temperature phase are small, but do not vanish in the thermodynamic limit, and are in good agreement with our replica symmetric calculations.   such corrections derive from the fact that the overlap between two typical chains is nonzero.   we explain why previous authors had come to the opposite conclusion, and discuss consequences for the thermodynamics of the model.   numerical results were obtained by simulating chains of length @xmath2 by means of the recent perm algorithm, in the coil and molten globular phases, well above the freezing temperature.   48 pt -1.5truecm -1.2 truecm 17 cm 23.3 cm         * * c
we present strong arguments that the deep structure of the quantum vacuum contains a web of microscopic wormholes or short - cuts.   we develop the concept of wormhole spaces and show that this web of wormholes generate a peculiar array of long - range correlations in the patterns of vacuum fluctuations on the planck scale.   we conclude that this translocal structure represents the common cause for both the bh - entropy - area law, the more general holographic principle and the entanglement phenomena in quantum theory. in   so far our approach exhibits a common structure which underlies both gravity and quantum theory on a microscopic scale. a central place in our analysis is occupied by a quantitative derivation of the distribution laws of microscopic wormholes in the quantum vacuum.   this makes it possible to address a number of open questions and controversial topics in the field of quantum gravity.   1.5 cm    0.5 cm    institut fr theoretische physik + universitt gttingen + friedrich - hund - platz 1 + 37077 gttingen germany + ( e - mail : requardt@theorie.physik.uni-goettingen.de )
we study cp violation in the two - body decay of a scalar tau into a neutralino and a tau, which should be probed at the lhc and ilc. from the normal tau polarization,   a cp asymmetry is defined which is sensitive to the cp phases of the trilinear scalar coupling parameter @xmath0, the gaugino mass parameter @xmath1, and the higgsino mass parameter @xmath2 in the stau - neutralino sector of the minimal supersymmetric standard model.   asymmetries of more than @xmath3 are obtained in scenarios with strong stau mixing. as a result, detectable cp asymmetries in stau decays at the lhc are found, motivating further detailed experimental studies for probing the susy cp phases.
an interacting boson model hamiltonian determined from hartree - fock - bogoliubov calculations with the new microscopic gogny energy density functional d1 m, is applied to the spectroscopic analysis of neutron - rich yb, hf, w, os and pt isotopes with mass @xmath0.   excitation energies and transition rates for the relevant low - lying quadrupole collective states are calculated by this method.   transitions from prolate to oblate ground - state shapes are analyzed as a function of neutron number @xmath1 in a given isotopic chain by calculating excitation energies, @xmath2(e2 ) ratios, and correlation energies in the ground state.   it is shown that such transitions tend to occur more rapidly for the isotopes with lower proton number @xmath3, when departing from the proton shell closure @xmath4.   the triaxial degrees of freedom turn out to play an important role in describing the considered mass region.   predicted low - lying spectra for the neutron - rich exotic hf and yb isotopes are presented.   the approximations used in the model and the possibilities to refine its predictive power are addressed.
the spherical hecke central ( shc ) algebra has been shown to act on the nekrasov instanton partition functions of @xmath0 gauge theories.   its presence accounts for both integrability and agt correspondence. on the other hand,   a specific limit of the omega background, introduced by nekrasov and shatashvili ( ns ), leads to the appearance of tba and bethe like equations. to unify these two points of view, we study the ns limit of the shc algebra.   we provide an expression of the instanton partition function in terms of bethe roots, and define a set of operators that generates infinitesimal variations of the roots.   these operators obey the commutation relations defining the shc algebra at first order in the equivariant parameter @xmath1.   furthermore, their action on the bifundamental contributions reproduces the kanno - matsuo - zhang transformation.   we also discuss the connections with the mayer cluster expansion approach that leads to tba - like equations.   * keywords : * ddaha, @xmath0 gauge theory, instanton partition function, agt correspondence +    apctp pre2014 - 010 +    spherical hecke algebra in the nekrasov - shatashvili limit    jean - emile bourgine +   + _ pohang, gyeongbuk 790 - 784, republic of korea _,
we present new ryle telescope ( rt ) observations of the sunyaev - zeldovich ( sz ) decrement from the cluster abell 773.   the field contains a number of faint radio sources that required careful subtraction.   we use _ asca _ observations to measure the gas temperature and a _ rosat _ hri image to model the gas density distribution. normalizing the gas distribution to fit the rt visibilities returns a value of @xmath0 of @xmath1 ( 1-@xmath2 errors ) for an einstein - de - sitter universe, or @xmath3 for a flat model with @xmath4.   the errors quoted include estimates of the effects of the principal errors : noise in the sz measurement, gas temperature uncertainty, and line - of - sight depth uncertainty.    cosmic microwave background   cosmology : observations  x - rays  distance scale  galaxies : clusters : individual ( a773 )
a stochastic second - order wave model is applied to assess the statistical properties of wave orbital velocity in random sea states below the water surface.   directional spreading effects as well as the dependency of the water depth are investigated by means of a monte - carlo approach. unlike for the surface elevation,   sub - harmonics dominate the second - order contribution to orbital velocity.   we show that a notable set - down occurs for the most energetic and steepest groups.   this engenders a negative skewness in the temporal evolution of the orbital velocity. a substantial deviation of the upper and lower tails of the probability density function from the gaussian distribution   is noticed ; velocities are faster below the wave trough and slower below the wave crest when compared with linear theory predictions.   second - order nonlinearity effects strengthen with reducing the water depth, while weaken with the broadening of the wave spectrum.   the results are confirmed by laboratory data.   corresponding experiments have been conducted in a large wave basin taking into account the directionality of the wave field.   as shown, laboratory data are in very good agreement with the numerical prediction.    wave orbital motion, second - order, wave statistics
we present relativistic analyses of 9257 measurements of times - of - arrival from the first binary pulsar, psr b1913 + 16, acquired over the last thirty - five years.   the determination of the `` keplerian '' orbital elements plus two relativistic terms completely characterizes the binary system, aside from an unknown rotation about the line of sight ; leading to a determination of the masses of the pulsar and its companion : @xmath0 and @xmath1, respectively.   in addition, the complete system characterization allows the creation of tests of relativistic gravitation by comparing measured and predicted sizes of various relativistic phenomena.   we find that the ratio of observed orbital period decrease due to gravitational wave damping ( corrected by a kinematic term ) to the general relativistic prediction, is @xmath2 ; thereby confirming the existence and strength of gravitational radiation as predicted by general relativity.   for the first time in this system, we have also successfully measured the two parameters characterizing the shapiro gravitational propagation delay, and find that their values are consistent with general relativistic predictions.   we have also measured for the first time in any system the relativistic shape correction to the elliptical orbit, @xmath3, although its intrinsic value is obscured by currently unquantified pulsar emission beam aberration.   we have also marginally measured the time derivative of the projected semimajor axis, which, when improved in combination with beam aberration modelling from geodetic precession observations, should ultimately constrain the pulsar s moment of inertia.
we have made a galactic extinction map of the cygnus region with 5@xmath0 spatial resolution.   the selected area is 80@xmath1 to 90@xmath2 in the galactic longitude and -4@xmath2 to 8@xmath2 in the galactic latitude.   the intensity at 140 @xmath3 m is derived from the intensities at 60 and 100 @xmath3 m of the _ iras _ data using the tight correlation between 60, 100, and 140 @xmath3 m found in the galactic plane.   the dust temperature and optical depth are calculated with 5@xmath0 resolution from the 140 and 100 @xmath3 m intensity, and @xmath4 is calculated from the optical depth. in the selected area, the mean dust temperature is 17 k, the minimum is 16 k, and the maximum is 30 k. the mean @xmath4 is 6.5 mag, the minimum is 0.5 mag, and the maximum is 11 mag.   the dust temperature distribution shows significant spatial variation on smaller scales down to 5@xmath0.   because the present study can trace the 5@xmath0-scale spatial variation of the extinction, it has an advantage over the previous studies, such as the one by schlegel, finkbeiner, & davis, who used the _   cobe_/dirbe data to derive the dust temperature distribution with a spatial resolution of 1@xmath2.   the difference of @xmath4 between our map and schlegel et al.s is @xmath5 3 mag.   a new extinction map of the entire sky can be produced by applying the present method.
we perform an updated model - independent analysis using the latest solar neutrino data obtained by @xmath0cl and @xmath1ga radiochemical experiments, and most notably by a large water - cherenkov detector superkamiokande with their 504 days of data taking.   we confirm that the astrophysical solutions to the solar neutrino problem are extremely disfavored by the data and a low - temperature modification of the standard solar model is excluded by more than 5 @xmath2.   we also propose a new way of illuminating the suppression pattern of various solar neutrino flux without invoking detailed flavor conversion mechanisms.   it indicates that the strong suppression of 7 neutrinos is no more true when the neutrino flavor conversion is taken into account.   # 1#1 # 1#1 7@xmath3be 8@xmath4b    0.5 cm
we perform detailed measurements of the geometrical characteristics of the percolating cluster of the magnetic monopole currents in the confining phase of the lattice @xmath0 gluodynamics.   the maximal abelian projection is used to define the monopoles.   the use of the geometrical language is motivated by recent observations that the full non - abelian action associated with the monopoles corresponds to point - like particles on the currently available lattices.   scaling behavior of various quantities is observed.
we present single - epoch radio afterglow observations of @xmath0 long - duration gamma - ray burst ( grb ) on a timescale of @xmath1 d after the burst.   these observations trace the afterglow evolution when the blastwave has decelerated to mildly- or non - relativistic velocities and has roughly isotropized.   we infer beaming - independent kinetic energies using the sedov - taylor self - similar solution, and find a median value for the sample of detected bursts of about @xmath2 erg, with a @xmath3 confidence range of @xmath4 erg.   both the median and @xmath3 confidence range are somewhat larger than the results of multi - wavelength, multi - epoch afterglow modeling ( including large beaming corrections ), and the distribution of beaming - corrected @xmath5-ray energies.   this is due to bursts in our sample with only a single - frequency observation for which we can only determine an upper bound on the peak of the synchrotron spectrum.   this limitation leads to a wider range of allowed energies than for bursts with a well - measured spectral peak.   our study indicates that single - epoch centimeter - band observations covering the spectral peak on a timescale of @xmath6 yr can provide a robust estimate of the total kinetic energy distribution with a small investment of telescope time. the substantial increase in bandwidth of the evla ( up to 8 ghz simultaneously with full coverage at @xmath7 ghz )   will provide the opportunity to estimate the kinetic energy distribution of grbs with only a few hours of data per burst.
in order to develop statistical methods for shapes with a tree - structure, we construct a shape space framework for tree - like shapes and study metrics on the shape space.   this shape space has singularities, corresponding to topological transitions in the represented trees.   we study two closely related metrics on the shape space, ted and qed.   qed is a quotient euclidean distance arising naturally from the shape space formulation, while ted is the classical tree edit distance. using gromov s metric geometry we gain new insight into the geometries defined by ted and qed.   we show that the new metric qed has nice geometric properties which facilitate statistical analysis, such as existence and local uniqueness of geodesics and averages. ted, on the other hand, does not share the geometric advantages of qed, but has nice algorithmic properties. we provide a theoretical framework and experimental results on synthetic data trees as well as airway trees from pulmonary ct scans.   this way, we effectively illustrate that our framework has both the theoretical and qualitative properties necessary to build a theory of statistical tree - shape analysis.    * keywords : * trees, tree metric, shape, anatomical structure, pattern matching, pattern recognition, geometry
the non - markovian dynamics of open quantum systems is still a challenging task, particularly in the non - perturbative regime at low temperatures. while the stochastic liouville - von neumann equation ( sln ) provides a formally exact tool to tackle this problem for both discrete and continuous degrees of freedom, its performance deteriorates for long times due to an inherently non - unitary propagator. here   we present a scheme which combines the sln with projector operator techniques based on finite dephasing times, gaining substantial improvements in terms of memory storage and statistics.   the approach allows for systematic convergence and is applicable in regions of parameter space where perturbative methods fail, up to the long time domain.   findings are applied to the coherent and incoherent quantum dynamics of two- and three - level systems. in the long time domain   sequential and super - exchange transfer rates are extracted and compared to perturbative predictions.
the open cluster ngc 6791 is among the oldest, most massive and metal - rich open clusters in the galaxy.   high - resolution @xmath0-band spectra from the apache point observatory galactic evolution experiment ( apogee ) of 11 red giants in ngc 6791 are analyzed for their chemical abundances of iron, oxygen, and sodium.   the abundances of these three elements are found to be homogeneous ( with abundance dispersions at the level of @xmath1 0.05 - 0.07 dex ) in these cluster red giants, which span much of the red - giant branch ( t@xmath2 @xmath1 3500k - 4600k ), and include two red - clump giants. from the infrared spectra, this cluster   is confirmed to be among the most metal - rich clusters in the galaxy ( @xmath3@xmath4 = 0.34 @xmath5 0.06 ), and is found to have a roughly solar value of  and slightly enhanced .   non - lte calculations for the studied na i lines in the apogee spectral region ( @xmath616373.86  and @xmath616388.85 ) indicate only small departures from lte ( @xmath7 0.04 dex ) for the parameter range and metallicity of the studied stars.   the previously reported double population of cluster members with different na abundances is not found among the studied sample.
the problem of quantum criticality in the context of itinerant ferro- or metamagnetism has received considerable attention [ s. a. grigera _ et.   al. _,   science * 294 *, 329 ( 2001 ) ; c. pfleiderer _ et.   al. _,   nature, * 414 *, 427 ( 2001 ) ].   it has been proposed that a new kind of quantum criticality is realised in materials such as or.   we show based on a mean - field theory that the low - temperature behaviour of the -layer ruthenates can be understood as a result of a van hove singularity ( ). we consider a single band whose fermi energy,, is close to the and deduce a complex phase diagram for the magnetism as a function of temperature, magnetic field and.   the location of with respect to the depends on the number of layers or can be tuned by pressure.   we find that the ferromagnetic quantum phase transition in this case is not of second but of first order, with a metamagnetic quantum critical endpoint at high magnetic field. despite its simplicity   this model describes well the properties of the uniform magnetism in the single, double and triple layer ruthenates.   we would like to emphasise that the origin of this behaviour lies in the band structure.
the first search for extra - terrestrial intelligence ( seti ) conducted with very long baseline interferometry ( vlbi ) is presented. by consideration of the basic principles of interferometry  , we show that vlbi is efficient at discriminating between seti signals and human generated radio frequency interference ( rfi ).   the target for this study was the star gliese  581, thought to have two planets within its habitable zone. on 2007   june 19, gliese  581 was observed for 8  hours at 1230 - 1544  @xmath0 with the australian long baseline array.   the dataset was searched for signals appearing on all interferometer baselines above five times the noise limit.   a total of 222 potential seti signals were detected and by using automated data analysis techniques, were ruled out as originating from the gliese  581 system. from our results we place an upper limit of @xmath1 on the power output of any isotropic emitter located in the gliese  581 system, within this frequency range.   this study shows that vlbi is ideal for targeted seti, including follow - up observations.   the techniques presented are equally applicable to next - generation interferometers, such as the long baselines of the _ square kilometre array ( ska)_.
recent vlbi observations have identified several compact radio sources which have symmetric structures on parsec scales, and exhibit absorption which appears to be associated with the active nucleus.   these sources are uniquely well suited to investigations into the physics of the central engines, in particular to studies of the kinematics of the gas within 100 pc of the core. in these compact sources, it is reasonable to assume that this circumnuclear material is accreting onto, and `` feeding '', the central engine.   we present results of  imaging studies of 3 symmetric radio galaxies which show evidence of a circumnuclear torus.   ,
different variants of mfdfa technique are applied in order to investigate various ( artificial and real - world ) time series.   our analysis shows that the calculated singularity spectra are very sensitive to the order of the detrending polynomial used within the mfdfa method.   the relation between the width of the multifractal spectrum ( as well as the hurst exponent ) and the order of the polynomial used in calculation is evident.   furthermore, type of this relation itself depends on the kind of analyzed signal.   therefore, such an analysis can give us some extra information about the correlative structure of the time series being studied.   pacs numbers : 05.45.df, 05.45.tp, 89.75.-k    @xmath0__institute of nuclear physics, polish academy of sciences, krakw, poland _   _ @xmath1__faculty of physics, mathematics and computer science, cracow university of technology, krakw, poland _ _    0.5 cm     _ corresponding author ; e - mail : pawel.oswiecimka@ifj.edu.pl_
we demonstrate an information transfer mechanism between two dissimilar remote inas / gaas quantum dots weakly coupled to a common photonic crystal microcavity.   bichromatic excitation in the s - state of one of the dots leads to the formation of dressed states due to the coherent coupling to the laser field, in resonance with the quantum dot.   information on the resulting dressed structure is read out through the photo - luminescence spectrum of the other quantum dot, as well as the cavity mode.   the effect is also observed upon exchange of the excitation and detection quantum dots.   this quantum dot inter - talk is interpreted in terms of a cavity - mediated coupling involving acoustic phonons.   a master equation for a three level system coherently pumped by the two lasers quantitatively describes the behavior of our system.   our result presents an important step towards scalable solid - state quantum networking based on coupled multi - quantum - dot - cavity systems, without the need of using identical quantum emitters.
using detailed spectral energy distribution fits we present evidence that submillimeter- and radio - bright gamma - ray burst host galaxies are hotter counterparts to submillimeter galaxies.   this hypothesis makes them of special interest since hotter submm galaxies are difficult to find and are believed to contribute significantly to the star formation history of the universe.
optical fibers confine and guide light almost unattenuated and thus convey light forces to polarizable nano - particles over very long distances.   radiation pressure forces arise from scattering of guided photons into free space while gradient forces are based on coherent scattering between different fiber modes or propagation directions.   interestingly, even scattering between co - propagating modes induces longitudinal forces as the transverse confinement of the light modes creates mode dependent longitudinal wave - vectors and photon momenta.   we generalize a proven scattering matrix based approach to calculate single as well as inter - particle forces to include several forward and backward propagating modes.   we show that an injection of the higher order mode only in a two mode fiber will induce a stationary tractor force against the injection direction, when the mode coupling to the lower order mode dominates against backscattering and free space losses.   generically this arises for non - absorbing particles at the center of a waveguide.   the model also gives improved predictions for inter - particle forces in evanescent nanofiber fields as experimentally observed recently.   surprisingly strong tractor forces can also act on whole optically bound arrays.
this is the first in a series of papers, in which we compute the third - order qcd corrections to top - antitop production near threshold in @xmath0 collisions.   the present paper provides a detailed outline of the strategy of computation in the framework of non - relativistic effective theory and the threshold expansion, applicable more generally to heavy - quark pair production near threshold.   it summarizes matching coefficients and potentials relevant to the next - to - next - to - next - to - leading order and ends with the master formula for the computation of the third - order green function.   the master formula is evaluated in part ii of the series.   tum - hep-919/13 + ttk-13 - 26 + sfb / cpp-13 - 110 + november 18, 2013    1.5 cm    * third - order correction to top - quark pair production near threshold i. effective theory set - up and matching coefficients *    m.  beneke@xmath1, y. kiyo@xmath2, k. schuller@xmath3 + _ @xmath4 physik department t31, james - franck - strae  1, _ + _ technische universitt mnchen, d85748 garching, germany _ + _ @xmath3 institut fr theoretische teilchenphysik und kosmologie, _ + _ rwth aachen university, d52056 aachen, germany _   + _ @xmath2 department of physics, juntendo university, _ + _ inzai, chiba 270 - 1695, japan _ +
in this work, we study the kondo effect of a quantum dot ( qd ) connected to leads and to a discrete set of one particle states provided by a quantum box represented by a quantum ring ( qr ) pierced by a magnetic flux side attached to the qd.   the interplay between the bulk kondo effect and the so called kondo box regime is studied. in this system   the qr energies can be continuously modified by the application of the magnetic field.   the crossover between these two regimes is analyzed by changing the connection of the qd to the qr from the weak to the strong coupling regime. in the weak coupling regime,   the differential conductance develops a sequence of fano - kondo antiresonances due to destructive interferences between the discrete quantum ring levels and the conducting kondo channel provided by the leads. in the strong coupling regime   the differential conductance has very sharp resonances when one of the kondo discrete sub - level characterizing the kondo box is tunned by the applied potential.   the conductance, the current fluctuations and the fano coefficient result to be the relevant physical magnitudes to be analyzed to reveal the physical properties of these two kondo regimes and the crossover region between them.   the results were obtained by using the slave boson mean field theory ( sbmft ).
the far - ultraviolet ( fuv ) channel of the cosmic origins spectrograph ( cos ) is designed to operate between 1130  and 1850, limited at shorter wavelengths by the reflectivity of the mgf@xmath0 protected aluminum reflective surfaces on the optical telescope assembly and on the cos fuv diffraction gratings. however, because the detector for the fuv channel is windowless, it was recognized early in the design phase that there was the possibility that cos would retain some sensitivity at shorter wavelengths due to the first surface reflection from the mgf@xmath0 coated optics.   preflight testing of the flight spare g140l grating revealed @xmath1 5% efficiency at 1066, and early on - orbit observations verified that the cos g140l/1230 mode was sensitive down to at least the lyman limit with 10 - 20 @xmath2 effective area between 912  and 1070, and rising rapidly to over 1000 @xmath2 beyond 1150.   following this initial work we explored the possibility of using the g130 m grating out of band to provide coverage down to 900.   we present calibration results and ray trace simulations for these observing modes and explore additional configurations that have the potential to increase spectroscopic resolution, signal to noise, and observational efficiency below 1130.
we make an inventory of the baryonic and gravitating mass in structures ranging from the smallest galaxies to rich clusters of galaxies. we find that the fraction of baryons converted to stars reaches a maximum between @xmath0 and @xmath1, suggesting that star formation is most efficient in bright galaxies in groups.   the fraction of baryons detected in all forms deviates monotonically from the cosmic baryon fraction as a function of mass. on the largest scales of clusters,   most of the expected baryons are detected, while in the smallest dwarf galaxies, fewer than 1% are detected. where these missing baryons reside   is unclear.
we study, both numerically and analytically, a binary - agent - resource ( b - a - r ) model consisting of @xmath0 agents who compete for a limited resource @xmath1, where @xmath2 is the maximum available resource per turn for all @xmath0 agents. as @xmath2 increases  , the system exhibits well - defined plateaux regions in the success rate which are separated from each other by abrupt transitions.   both the maximum and the mean success rates over each plateau are ` quantized' for example, the maximum success rate forms a well - defined sequence of simple fractions as @xmath2 increases.   we present an analytic theory which explains these surprising phenomena both qualitatively and quantitatively.   the underlying cause of this complex behavior is an interesting self - organized phenomenon in which the system, in response to the global resource level, effectively avoids particular patterns of historical outcomes.   pacs nos. :   02.50.le, 05.65.+b, 05.40.-a, 89.90.+n
motivated by the stm experimental data on bi@xmath0sr@xmath0cacu@xmath0o@xmath1 which indicate the tunneling conductance asymmetry @xmath2, we report that such a behavior can be explained in terms of the boson fermion model.   it has been shown in the recent studies, based on various selfconsistent techniques to capture the many - body effects, that the low energy spectrum of the boson fermion model is featured by an appearance of the pseudogap at @xmath3.   we argue that the pseudogap structure has to exhibit a particle - hole asymmetry.   this asymmetry may eventually depend on the boson concentration.
convergent infinite products, indexed by all natural numbers, in which each factor is a rational function of the index, can always be evaluated in terms of finite products of gamma functions.   this goes back to euler.   a purpose of this note is to demonstrate the usefulness of this fact through a number of diverse applications involving multiplicative partitions, entries in ramanujan s notebooks, the chowla  selberg formula, and the thue   morse sequence.   in addition, we propose a numerical method for efficiently evaluating more general infinite series such as the slowly convergent kepler  bouwkamp constant.
searches for supersymmetric particles in channels with one or more photons and missing energy have been performed with data collected by the aleph detector at lep.   the data consist of 11.1  at @xmath0, 1.1  at 170  and 9.5  at 172 gev.   the  cross section is measured.   the data are in good agreement with predictions based on the standard model, and are used to set upper limits on the cross sections for anomalous photon production.   these limits are compared to two different susy models and used to set limits on the neutralino mass. a limit of 71  at 95% c.l.   is set on the mass of the lightest neutralino ( @xmath1 3 ns ) for the gauge - mediated supersymmetry breaking and lnz models.    0t@xmath2   2@xmath3 1@xmath4 2x2@xmath5    european laboratory for particle physics ( cern )    cern - ppe/97 - 122 + september 4 1997 +    * searches for supersymmetry in the photon(s ) plus missing energy channels at @xmath6 = 161 gev and 172 gev *    the aleph collaboration@xmath7    _ ( to be submitted to physics letters b ) _   +    = 10000    * the aleph collaboration *
multipersistence homology modules were introduced by g.carlsson and a.zomorodian @xcite which gave, together with g.singh @xcite, an algorithm to compute their grbner bases.   although their algorithm has polynomial complexity when the chain modules are free, i.e. in the one - critical case, it might be exponential in general.   we give a new presentation of multipersistence homology modules, which allows us to design an algorithm to compute their grbner bases always in polynomial time by avoiding the mapping telescope.   _ mathematics subject classification ( 2010 ) _ : 55u99, 55n99, 13p10.   _ keywords _ : computational topology, commutative algebra, persistent homology and grbner bases.
improved results using a method similar to the munn - silbey approach have been obtained on the temperature dependence of transport properties of an extended holstein model incorporating simultaneous diagonal and off - diagonal exciton - phonon coupling.   the hamiltonian is partially diagonalized by a canonical transformation, and optimal transformation coefficients are determined in a self - consistent manner. calculated transport properties exhibit substantial corrections on those obtained previously by munn and silbey for a wide range of temperatures thanks to a numerically exact evaluation and an added momentum - dependence of the transformation matrix.   results on the diffusion coefficient in the moderate and weak coupling regime show distinct band - like and hopping - like transport features as a function of temperature.
we have measured the brightness variations in @xmath0 carinae for the past six years using the hubble space telescope space telescope imaging spectrograph and advanced camera for surveys. unlike ground - based data, observations by the hst allow direct measurement of the brightness of the central star by resolving it from the surrounding bright ejecta.   we find interesting behavior during 2003 in the continuum and h@xmath1 emission.   the data show that the established long term brightening trend of @xmath0 car continues, including regular events which coincide with the 5.5 year spectroscopic cycle and other more rapid and unexpected variations.   in addition to the hst data, we also present ground - based data obtained from the aavso which show many of the same features.   the dip in the apparent brightness of the central star at the time of the 2003.5 event is wavelength dependent with no decrease in the continuum.   these observations cast doubt on a simple eclipse or occultation as the explanation for the dip and place constraints on the models for the event.
we consider the spin 1/2 model coupled to a slowly varying magnetic field in the presence of a weak damping represented by a lindblad - form operators.   we show that berry s geometrical phase remains unaltered by the two dissipation mechanism considered.   dissipation effects are twofold : a shrinking in the modulus of the bloch s vector, which characterizes coherence loss and a time dependent ( dissipation related ) precession angle.   we show that the line broadening of the fourier transformation of the components of magnetization is only due to the presence of dissipation.   pacs numbers : 03.65.bz, 03.65.-w, 05.30, 42.50.lc    keywords : berry s phase, lindblad - form operator, decoherence
the solid - liquid interface free energy @xmath0is a key parameter controlling nucleation and growth during solidification and other phenomena.   there are intrinsic difficulties in obtaining accurate experimental values, and the previous approaches to compute @xmath0with atomistic simulations are computationally demanding.   we propose a new approach, which is to obtain @xmath0from a free energy map of the phase transition reconstructed by metadynamics.   we apply this to the benchmark case of a lennard - jones potential and the results confirm the most reliable data obtained previously.   we demonstrate several advantages of our new approach : it is simple to implement, robust and free of hysteresis problems, it allows a rigorous and unbiased estimate of the statistical uncertainty and it returns a good estimate of of the thermodynamic limit with system sizes of a just a few hundred atoms.   it is therefore attractive for using with more realistic and specific models of interatomic forces.
the low - energy effective hamiltonian of three coupled spin chains with periodic boundary conditions ( spin tube ) is expressed, in the limit of strong interchain coupling, in terms of xxz chains coupled by biquadratic exchange interaction.   a similar effective model was also proposed to describe the coupling of spins to orbital degrees of freedom in materials such as @xmath0.   we investigate the effective model by means of bosonization and renormalization group techniques, and find that the generic phase diagram comprises a gapless region and gapped regions consisting of a spin liquid phase and various antiferromagnetic phases.   we discuss the properties of the spin liquid phase, in particular the nature of the ground state and of the elementary excitations above it.   we then study the effect of a magnetic field, and conclude that a strong enough magnetic field can suppress the dimerized phase leading to a two component luttinger liquid.   the critical exponents at the transition gapful - gapless are calculated and shown to be _ non - universal _ in the spin tube case or the generic spin orbital problem.   pacs numbers:75.10.jm, 75.30.kz, 75.40.gb    _ keywords _ : spin - tube, bosonization and renormalization group, spin - liquid
the statistics of steps and dwell times in reversible molecular motors differ from those of cycle completion in enzyme kinetics.   the reason is that a step is only one of several transitions in the mechanochemical cycle. as a result  , theoretical results for cycle completion in enzyme kinetics do not apply to stepping data. to allow correct parameter estimation, and to guide data analysis and experiment design  , a theoretical treatment is needed that takes this observation into account. in this paper, we model the distribution of dwell times and number of forward and backward steps using first passage processes, based on the assumption that forward and backward steps correspond to different directions of the same transition.   we extend recent results for systems with a single cycle and consider the full dwell time distributions as well as models with multiple pathways, detectable substeps, and detachments.   our main results are a symmetry relation for the dwell time distributions in reversible motors, and a relation between certain relative step frequencies and the free energy per cycle.   we demonstrate our results by analyzing recent stepping data for a bacterial flagellar motor, and discuss the implications for the efficiency and reversibility of the force - generating subunits. + _ key words : _ motor proteins ; single molecule kinetics ; enzyme kinetics ; flagellar motor ; markov process ; non - equilibrium fluctuations.
we present deep spectroscopy with the keck telescope of eight galaxies in the luminous x - ray cluster 054 at @xmath0.   the data are combined with imaging observations from the _ hubble space telescope _ ( hst ).   the spectroscopic data are used to measure the internal kinematics of the galaxies, and the hst data to measure their structural parameters.   six galaxies have early - type spectra, and two have `` e+a '' spectra.   the galaxies with early - type spectra define a tight fundamental plane ( fp ) relation. the evolution of the mass - to - light ratio is derived from the fp.   the @xmath1 ratio evolves as @xmath2 ( @xmath3, @xmath4 ).   the observed evolution of the @xmath1 ratio provides a combined constraint on the formation redshift of the stars, the imf, and cosmological parameters. for a salpeter imf ( @xmath5 )   we find that @xmath6 and @xmath7 with 95% confidence.   the constraint on the formation redshift is weaker if @xmath8 : @xmath9 if @xmath3 and @xmath10. at present   the limiting factor in constraining @xmath11 and @xmath12 from the observed luminosity evolution of early - type galaxies is the poor understanding of the imf.   we find that if @xmath13 the imf must be significantly steeper than the salpeter imf ( @xmath14 ).   # 1xxxx # 1 xxxx 50min@xmath15 054ms1054@xmath1603
we consider the effect of stellar activity, as measured by x - ray luminosity, on metallicities of solar - neighborhood f and g dwarfs derived from strmgren photometry.   rocha - pinto & maciel found evidence that strmgren colors systematically underpredict  for stars with extremely high h & k emission.   we investigate whether a recent photometric metallicity calibration derived by martell & laughlin might be subject to this effect, and whether the amount of underprediction could reliably be expressed as a function of @xmath0. among those calibration stars used by martell & laughlin which are also in the bright star catalogue and detected in the _ rosat _ all - sky survey there is no evidence for a correlation between photometric metallicity and stellar activity.   however, many of the `` very active stars '' on which the rocha - pinto & maciel result was based are members of interacting binaries or are very young in age, and are not included in the x - ray sample that we are using. among normal dwarf stars   it appears that stellar activity has little effect on the metallicity calibration of strmgren colors.
we present the qcd analysis of the out - of - event - plane momentum distribution in dis events with high @xmath0 jets.   the achieved accuracy allows the measurement of the running coupling and the study of non - perturbative effects, in particular the test of universality of power corrections in a new experimental regime.   = by -1
we present the first contemporaneous 43ghz and 86ghz vlbi images of the v=1 j=2@xmath01 and j=1@xmath00 sio masers in the orion - kl nebula. both maser species exhibit the same general morphology of earlier j=1@xmath00 maser images which appear to trace the edges of a bi - polar conical outflow.   surprisingly, the j=2@xmath01 masers form further from the central protostar than the j=1@xmath00 masers, a fact not readily explained by current sio maser pumping models.   the average magnitude of offsets between corresponding regions of the two masing transitions is approximately 14% of the total radial extent of the sio maser emission.   this offset indicates that each transition must trace different physical conditions.
we revisit the scattering of surface plasmons by shallow surface defects for both protrusions and indentations of various lengths, which are deemed infinite in one - dimension parallel to the surface.   subwavelength protrusions and indentations of equal shape present different scattering coefficients when their height and width are comparable. in this case  , a protrusion scatters plasmons like a vertical point - dipole on a plane, while an indentation scatters like a horizontal point - dipole on a plane.   we corroborate that long and shallow asymmetrically - shaped surface defects have very similar scattering, as already found with approximate methods. in the transition from short shallow scatterers to long shallow scatterers   the radiation can be understood in terms of interference between a vertical and a horizontal dipole.   the results attained numerically are exact and accounted for with analytical models.
we study intermittency as a departure from self - similarity of the solar wind magnetic turbulence and investigate the evolution with the heliocentric distance and latitude.   we use data from the _ ulysses _ spacecraft measured during two solar minima ( 1997 - 1998 and 2007 - 2008 ) and one solar maximum ( 1999 - 2001 ).   in particular, by modeling a multifractal spectrum, we revealed the intermittent character of turbulence in the small - scale fluctuations of the magnetic field embedded in the slow and fast solar wind.   generally, at small distances from the sun, in both the slow and fast solar wind, we observe the high degree of multifractality ( intermittency ) that decreases somewhat slowly with distance and slowly with latitude.   the obtained results seem to suggest that generally intermittency in the solar wind has a solar origin.   however, the fast and slow streams, shocks, and other nonlinear interactions can only be considered as the drivers of the intermittent turbulence.   it seems that analysis shows that turbulence beyond the ecliptic plane evolves too slowly to maintain the intermittency with the distance and latitude.   moreover, we confirm that the multifractality and intermittency are at a lower level than in the ecliptic, as well as the existence of symmetry with respect to the ecliptic plane, suggesting that there are similar turbulent properties observed in the two hemispheres.
we report observations of a new am herculis binary identified as the optical counterpart of the x - ray source rx  j1313.23259, detected during the rosat all - sky survey ( rass ).   it has an orbital period of 251  min and is strongly modulated at optical wavelengths.   the long - term behavior is characterized by a pronounced variation in x - rays between the rass and two subsequent pointings ( decrease by a factor 40 in count rate ) and by moderate changes in the optical brightness ( up to a factor 5 ).   the x - ray spectrum is dominated by a soft quasi - blackbody component, with a smaller contribution from thermal bremsstrahlung.   measurements of high circular polarization confirm its classification as a polar with a magnetic field strength of 56  mg.   the average visual magnitude of rx  j1313.23259 is @xmath0, for its distance we get @xmath1  200  pc.
the relevance of storage - ring electron - ion recombination experiments for astrophysics is outlined. in particular, the role of low - energy dielectronic - recombination resonances is discussed. a bibliographic compilation of electron - ion recombination measurements with cosmically abundant ions is provided.
a driven system of three species of particle diffusing on a ring is studied in detail.   the dynamics is _ local _ and conserves the three densities. a simple argument suggesting that the model should phase separate and break the translational symmetry is given.   we show that for the special case where the three densities are equal the model obeys detailed balance and the steady - state distribution is governed by a hamiltonian with asymmetric long - range interactions.   this provides an explicit demonstration of a simple mechanism for breaking of ergodicity in one dimension.   the steady state of finite - size systems is studied using a generalized matrix product ansatz.   the coarsening process leading to phase separation is studied numerically and in a mean - field model.   the system exhibits slow dynamics due to trapping in metastable states whose number is exponentially large in the system size. the typical domain size is shown to grow logarithmically in time.   generalizations to a larger number of species are discussed.
dynamics of fluctuations in unstable bose - einstein condensates is analyzed by the solution of approximate operator equations. in the case of a condensate with a negative scattering length   the present treatment describes a delay of collapse, in agreement with recent experiments. in the case of a collision of two condensate wavepackets   it is shown that quantum effects lead to a bose enhancement of elastic - scattering losses. in both cases   the noncondensate atoms are formed as entangled pairs in squeezed states.
in this paper we determine the phase diagrams ( for @xmath0 as well as @xmath1 ) of the penson - kolb - hubbard model for two dimensional square lattice within hartree - fock mean - field theory focusing on investigation of superconducting phases and possibility of the occurrence of the phase separation.   we obtain that the phase separation, which is a state of coexistence of two different superconducting phases ( with @xmath2-wave and @xmath3-wave symmetries ), occurs in define range of the electron concentration.   in addition, increasing temperature can change the symmetry of the superconducting order parameter ( from @xmath3-wave into @xmath2-wave ).   the system considered exhibits also an interesting multicritical behaviour including bicritical points.
gas accreting onto a galaxy will be of low metallicity while halo gas due to a galactic fountain will be of near - solar metallicity.   we test these predictions by measuring the metal absorption line properties of halo gas 5 kpc above the plane of the edge - on galaxy ngc 891, using observations taken with hst / stis toward a bright background quasar.   metal absorption lines of,  and  in the halo of ngc 891 are clearly seen, and when combined with recent deep  observations, we are able to place constraints on the metallicity of the halo gas for the first time.   the  line width defines the line broadening, from which we model opacity effects in these metal lines, assuming the absorbing gas is continuously distributed in the halo.   the gas - phase metallicities are  = @xmath0 and  = @xmath1 ( statistical errors ) and this difference is probably due to differential depletion onto grains. when corrected for such depletion using galactic gas as a guide, both elements have approximately solar or even supersolar abundances.   this suggests that the gas is from the galaxy disk, probably expelled into the halo by a galactic fountain, rather than from accretion of intergalactic gas, which would have a low metallicity.   the abundances would be raised by significant amounts if the absorbing gas lies in a few clouds with thermal widths smaller than the rotational velocity of the halo.   if this is the case, both the abundances and  would be supersolar.
finding optimal solutions for multi - unit combinatorial auctions is a hard problem and finding approximations to the optimal solution is also hard.   we investigate the use of branch - and - bound techniques : they require both a way to bound from above the value of the best allocation and a good criterion to decide which bids are to be tried first.   different methods for efficiently bounding from above the value of the best allocation are considered.   theoretical original results characterize the best approximation ratio and the ordering criterion that provides it.   we suggest to use this criterion.
we present a multi - wavelength observation of a solar flare occurring on 2006 december 13 with _ hinode _, _ rhessi _, and the nobeyama radio observatory, to study the electron acceleration site and mechanism.   the solar optical telescope ( sot ) on board _ hinode _ observed elongated flare ribbons, and _ rhessi _ observed double - footpoint hard x - ray ( hxr ) sources appearing in part of the ribbons.   a photospheric vector magnetogram obtained from sot reveals that the hxr sources are located at the region where horizontal magnetic fields change the direction.   the region is interpreted as the footpoint of magnetic separatrix.   microwave images taken with the nobeyama radioheliograph show a loop structure connecting the hxr sources.   the brighter parts of the microwave intensity are located between the top and footpoints of the loop.   we consider these observations as an evidence of the electron acceleration near the magnetic separatrix and injection parallel to the field line.
we propose a fundamental theory whose low - energy effective theory provides a phenomenological description of electroweak baryogenesis, radiative neutrino mass generation, and dark matter.   the model is based on susy su(2)@xmath0 gauge theory with confinement, and the model contains new @xmath1 discrete symmetry and @xmath1-odd right - handed neutrino superfields.   the higgs sector in the low energy effective theory of this model below confinement scale is described by fifteen mesonic superfields of fundamental su(2)@xmath0 doublets.   we present a benchmark scenario of this model, where all the constraints from the current neutrino, dark matter, lepton flavour violation and lhc data are satisfied.   we also discuss how to test the scenario by the future collider experiments.
nano   particles are of great interest in fundamental and applied research. however, their accurate visualization is often difficult and the interpretation of the obtained images can be complicated.   we present a comparative scanning electron microscopy and helium ion microscopy study of cetyltrimethylammonium  bromide ( ctab ) coated gold nano  rods. using both methods   we show how the gold core as well as the surrounding thin ctab shell can selectively be visualized.   this allows for a quantitative determination of the dimensions of the gold core or the ctab shell.   the obtained ctab shell thickness of 1.0nm1.5 nm is in excellent agreement with earlier results using more demanding and reciprocal space techniques.   7 9 3    helium ion microscopy, scanning electron microscopy, nano  particles
* motivation : * the investigation of topological modifications of the gene interaction networks in cancer cells is essential for understanding the desease.   we study gene interaction networks in various human cancer cells with the random matrix theory.   this study is based on the cancer network galaxy ( tcng ) database which is the repository of huge gene interactions inferred by bayesian network algorithms from 256 microarray experimental data downloaded from ncbi geo.   the original geo data are provided by the high - throughput microarray expression experiments on various human cancer cells.   we apply the random matrix theory to the computationally inferred gene interaction networks in tcng in order to detect the universality in the topology of the gene interaction networks in cancer cells.   + * results : * we found the universal behavior in almost one half of the 256 gene interaction networks in tcng.   the distribution of nearest neighbor level spacing of the gene interaction matrix becomes the wigner distribution when the network is large ( condensed ), and it behaves as poisson distribution when the network is smaller.   we also observe the transition between the poisson and the wigner distributions as the threshold of confidence factor of the gene interactions is shifted.   we expect that the random matrix theory provides an effective analytical method for investigating the huge interaction networks of the various transcripts in cancer cells.   + * * contact:**akikkawa@oist.jp +
the goal of the second flight of the medium scale anisotropy measurement ( msam1 - 94 ) was to confirm the measurement of cosmic microwave background radiation ( cmbr ) anisotropy made in the first flight ( msam1 - 92 ).   the cmbr anisotropy and interstellar dust emission signals from the two flights are compared by forming the sum and difference of those portions of the data with the same pointings on the sky.   the difference data are consistent with a null detection, while the summed data show significant signal. we conclude that msam1 - 92 and msam1 - 94 measured the same celestial signal.   3@xmath0 # 1_#1 _ # 1@xmath1 # 1@xmath2
by making use of a simple model that captures the key features of the anomalous maxwell equations, we study the role of inhomogeneities on the evolution of magnetic fields in a chiral plasma.   we find that inhomogeneities of the chiral asymmetry by themselves do not prevent the anomaly - driven inverse cascade and, as in the homogeneous case, the magnetic helicity is transferred from shorter to longer wavelength helical modes of the magnetic field.   however, we also find that the evolution appears to be sensitive to the effects of diffusion. in the case   when diffusion is negligible, the inverse cascade slows down considerably compared to the homogeneous scenario. in the case of the primordial plasma, though, we find that the diffusion is substantial and efficiently suppresses chiral asymmetry inhomogeneities. as a result,   the inverse cascade proceeds practically in the same way as in the chirally homogeneous model.
we present a numerical study on an interacting monomer - dimer model with nearest neighbor repulsion on a square lattice, which possesses two symmetric absorbing states.   the model is observed to exhibit two nearby continuous transitions : the @xmath0 symmetry - breaking order - disorder transition and the absorbing transition with directed percolation criticality.   we find that the symmetry - breaking transition shows a non - ising critical behavior, and that the absorbing phase becomes critical, in the sense that the critical decay of the dimer density observed at the absorbing transition persists even within the absorbing phase.   our findings call for further studies on the microscopic models and corresponding continuum description belonging to the generalized voter university class.
the study of near  threshold meson production in @xmath0 and @xmath1 collisions involving polarized beams and polarized targets offers the rare opportunity to gain insight into short   range features of the nucleon  nucleon interaction.   the cooler synchrotron cosy at fz   jlich is a unique environment to perform such studies.   measurements of polarization observables require a cylindrically symmetrical detector, capable to measure the momenta and the directions of outgoing charged hadrons.   the wide energy range of cosy leads to momenta of outgoing protons to be detected in a single meson production reaction between 300 and 2500  mev / c.   scattering angles of protons to be covered extend to about @xmath2 in the laboratory system.   an azimuthal angular coverage of the device around 98% seems technically achievable.   the required magnetic spectrometer could consist of a superconducting toroid, providing fields around 3  t.
the glass transition remains one of the great unsolved mysteries of contemporary condensed matter physics.   when crystallization is bypassed by rapid cooling, a supercooled liquid, retaining amorphous particle arrangment, results.   the physical phenomenology of supercooled liquids is as vast as it is interesting.   most significant, the viscosity of the supercooled liquid displays an incredible increase over a narrow temperature range.   eventually, the supercooled liquid ceases to flow, becomes a glass, and gains rigidity and solid - like behaviors.   understanding what underpins the monumental growth of viscosity, and how rigidity results without long range order is a long - sought goal.   many theories of the glassy slowdown require the growth of static lengthscale related to structure with lowering of the temperature.   to that end, we have proposed a new, natural lengthscale- `` the shear penetration depth ''.   this lengthscale quantifies the structural connectivity of the supercooled liquid.   the shear penetration depth is defined as the distance up to which a shear perturbation applied to the boundary propagates into the liquid.   we provide numerical data, based on the simulations of @xmath0, illustrating that this length scale exhibits dramatic growth and eventual divergence upon approach to the glass transition.   we further discuss this in relation to percolating structural connectivity and a new theory of the glass transition.   january 2016
the production of positive pions and neutrons by cosmic muons at underground sites of various depths is investigated.   we first test the equivalent photon method in the particular case of @xmath0 excitation by the muon.   we find that this method, when it neglects the momentum dependence of the transverse response, reproduces remarkably well the theoretical muon cross section.   this success has lead us to apply the method to higher energies, where it has not been tested.   we evaluate in this way the production of positive pions in liquid scintillator from known photo - absorption cross sections. at a shallow depth of 20 meters   our estimate reproduces the measurement. as for the neutron emission,   we include the obvious sources, such as the giant - resonance excitation, the quasi - deuteron process, the quasi - free pion production as well as neutrons emitted following pion capture.   our evaluation underestimates the number of neutrons produced and finds a too weak dependence on the depth.   this suggests that secondary neutron production is important at all depths.   # 1 = 0.1 cm    = 40 mm    pacs numbers : 25.30.mr, 25.20.-x, 25.40.sc
we study the reduced dynamics of interacting spins, each coupled to its own bath of bosons.   we derive the solution in analytic form in the white - noise limit and analyze the rich behaviors in diverse limits ranging from weak coupling and/or low temperature to strong coupling and/or high temperature.   we also view the one spin as being coupled to a spin - boson environment and consider the regimes in which it is effectively nonlinear, and in which it can be regarded as a resonant bosonic environment.
we consider the structure of self - gravitating marginally stable accretion disks in galactic centers in which a small fraction of the disk mass has been converted into proto - stars.   we find that proto - stars accrete gaseous disk matter at prodigious rates. mainly due to the stellar accretion luminosity  , the disk heats up and geometrically thickens, shutting off further disk fragmentation.   the existing proto - stars however continue to gain mass by gas accretion. as   a results, the initial mass function for disk - born stars at distances @xmath0 parsec from the super - massive black hole should be top - heavy.   the effect is most pronounced at around @xmath1 parsec.   we suggest that this result explains observations of rings of young massive stars in our galaxy and in m31, and predict that more of such rings will be discovered.   # 1    galaxy : centre  accretion : accretion discs  galaxies : active  stars : formation
numerous theoretical models have long proposed that a strong he ii @xmath0 emission line is the most prominent and unique feature of massive population iii ( pop iii ) stars in high redshift galaxies.   the he ii @xmath1 line strength can constrain the mass and imf of pop iii stars.   we use f132n narrowband filter on the hubble space telescope s ( hst ) wide field camera 3 ( wfc3 ) to look for strong he ii @xmath1 emission in the galaxy bdf-521 at @xmath2, one of the most distant spectroscopically - confirmed galaxies to date. using deep f132n narrowband imaging, together with our broadband imaging with f125w and f160w filters  , we do not detect he ii emission from this galaxy, but place a 2@xmath3 upper limit on the flux of @xmath4.   this measurement corresponds to a 2@xmath3 upper limit on the pop iii star formation rate ( sfr@xmath5 ) of @xmath6, assuming a salpeter imf with @xmath7. from the high signal - to - noise broadband measurements in f125w and f160w  , we fit the uv continuum for bdf-521.   the spectral flux density is @xmath8  @xmath9, which corresponds to an overall unobscured sfr of @xmath10 5 m@xmath11.   our upper limit on sfr@xmath5 suggests that massive pop iii stars represent @xmath12% of the total star formation.   further, the hst high resolution imaging suggests that bdf-521 is an extremely compact galaxy, with a half - light radius of @xmath13 kpc.
grain boundaries are topological defects that often have a disordered character.   disorder implies that understanding general trends is more important than accurate investigations of individual grain boundaries. here   we present trends in the grain boundaries of graphene.   we use density - functional tight - binding method to calculate trends in energy, atomic structure ( polygon composition ), chemical reactivity ( dangling bond density ), corrugation heights ( inflection angles ), and dynamical properties ( vibrations ), as a function of lattice orientation mismatch. the observed trends and their mutual interrelations   are plausibly explained by structure, and supported by past experiments.
the pixel detector of cms can be used to reconstruct very low @xmath0 charged particles down to about 0.1  gev/@xmath1.   this can be achieved with high efficiency, good resolution and a negligible fake rate for elementary collisions. in the case of central pbpb collisions   the fake rate can be kept low for @xmath2  gev/@xmath1.   in addition, the detector can be employed for identification of neutral hadrons ( v0s ) and converted photons.
nonreciprocal effective interaction forces can occur between mesoscopic particles in colloidal suspensions that are driven out of equilibrium.   these forces violate newton s third law on coarse - grained length and time scales. here   we explore the statistical mechanics of brownian particles with nonreciprocal effective interactions.   our model system is a binary fluid mixture of spherically symmetric, diffusiophoretic mesoscopic particles, and we focus on the time - averaged particle pair- and triplet - correlation functions.   based on the many - body smoluchowski equation we develop a microscopic statistical theory for the particle correlations and test it by computer simulations. for model systems in two and three spatial dimensions, we show that nonreciprocity induces distinct nonequilibrium pair correlations.   our predictions can be tested in experiments with chemotactic colloidal suspensions.
in this article we summarise on - going work on the so - called gaia fgk benchmark stars.   this work consists of the determination of their atmospheric parameters and of the construction of a high - resolution spectral library.   the definition of such a set of reference stars has become crucial in the current era of large spectroscopic surveys. only with homogeneous and well documented stellar parameters   can one exploit these surveys consistently and understand the structure and history of the milky way and therefore other of galaxies in the universe.       milky way structure - calibration of stellar parameters - reference libraries
we investigate theoretically the morphology of a thin nematic film adsorbed at flat substrate patterned by stripes with alternating aligning properties, normal and tangential respectively. we construct a simple `` exactly - solvable '' effective interfacial model where   the liquid crystal distortions are accounted for via an effective interface potential.   we find that chemically patterned substrates can strongly deform the nematic - air interface.   the amplitude of this substrate - induced undulations increases with decreasing average film thickness and with increasing surface pattern pitch.   we find a regime where the interfacial deformation may be described in terms of a material - independent universal scaling function.   surprisingly, the predictions of the effective interfacial model agree semi - quantitatively with the results of the numerical solution of a full model based on the landau - de gennes theory coupled to a square - gradient phase field free energy functional for a two phase system.
the square kilometer array will have the sensitivity, spatial resolution, and frequency resolution to provide new scientific knowledge of evolved stars.   four basic areas of scientific exploration are enhanced by the construction of the ska : 1 ) detection and imaging of photospheric radio continuum emission and position correlation with maser distributions, 2 ) imaging of thermal dust emission around evolved stars and the detailed structures of their circumstellar winds ( again, including comparison with maser distributions ), 3 ) study of cm - wavelength molecular line transitions and the circumstellar chemistry around both o - rich and c - rich evolved stars and 4 ) the possible observation of polarized emission due to the influence of the magnetic fields of agb stars. since this short chapter is not meant to be a review article, a comprehensive reference list has not been generated.   i have selected just one or perhaps two references for citations where appropriate.
we present a brief critical review of the proposals for quantum computation with trapped ions, with particular emphasis on the possibilities for quantum computation _ without _ the need for cooling to the quantum ground state of the ions collective oscillatory modes.   -0.5 in 9.3 in    la - ur-00 - 1436
we compute low - lying eigenmodes of the gauge covariant laplace operator on the lattice at finite temperature. for classical configurations   we show how the lowest mode localizes the monopole constituents inside calorons and that it hops upon changing the boundary conditions. the latter effect we observe for thermalized backgrounds, too,   analogously to what is known for fermion zero modes.   we propose a new filter for equilibrium configurations which provides link variables as a truncated sum involving the laplacian modes.   this method not only reproduces classical structures, but also preserves the confining potential, even when only a few modes are used.
we study decoherence of a quantum dot charge qubit due to coupling to piezoelectric acoustic phonons in the born - markov approximation. after including appropriate form factors, we find that phonon decoherence rates are one to two orders of magnitude weaker than was previously predicted.   we calculate the dependence of the @xmath0-factor on lattice temperature, quantum dot size, and interdot coupling.   our results suggest that mechanisms other than phonon decoherence play a more significant role in current experimental setups.
this work treats the effects of disorder and interactions in a quantum hall ferromagnet, which is realized in a two - dimensional electron gas ( 2deg ) in a perpendicular magnetic field at landau level filling factor @xmath0.   we study the problem by projecting the original fermionic hamiltonian into magnon states, which behave as bosons in the vicinity of the ferromagnetic ground state.   the approach permits the reformulation of a strongly interacting model into a non - interacting one.   the latter is a non - perturbative scheme that consists in treating the two - particle neutral excitations of the electron system as a bosonic single - particle.   indeed, the employment of bosonization facilitates the inclusion of disorder in the study of the system.   it has been shown previously that disorder may drive a quantum phase transition in the hall ferromagnet.   however, such studies have been either carried out in the framework of nonlinear sigma model, as an effective low - energy theory, or included the long - range coulomb interaction in a quantum description only up to the hartree - fock level. here  , we establish the occurrence of a disorder - driven quantum phase transition from a ferromagnetic 2deg to a spin glass phase by taking into account interactions between electrons up to the random phase approximation level in a fully quantum description.
we construct a starburst model for the hidden starbursts in arp 220 based on the new starburst99 models of leitherer et al. comparing these stellar population synthesis models with observations,   we show that the hidden power source must be due to star formation ( as opposed to an agn ) at the 50% level or more in order to avoid an ionizing photon excess problem, and this starburst must be young ( @xmath0 yr ).   we derive a current star formation rate of @xmath1 yr@xmath2, and an extinction @xmath3 mag for our line of sight to this hidden starburst.
we consider a model of dynamical neutrino masses via the see - saw mechanism.   nambu - goldstone bosons ( majorons ) arise associated with the formation of the heavy right - handed majorana masses.   these bosons then acquire naturally soft masses ( become pngb s ) at loop level via the higgs - yukawa mass terms.   these models, like the original neutrino pngb quintessence schemes of the 1980 s @xcite that proceed through the dirac masses, are natural, have cosmological implications through mass varying neutrinos, long range forces, and provide a soft potential for dark energy.   we further argue that these models can explain leptogenesis naturally through the decays of the right - handed neutrinos.   do - th 06/06 + july 26, 2006    * neutrino phenomenology, dark energy and leptogenesis from + pseudo - nambu - goldstone bosons + *
hawking and the author have proposed a class of singular, finite action instantons for defining the initial conditions for inflation.   vilenkin has argued they are unacceptable.   he exhibited an analogous class of asymptotically flat instantons which on the face of it lead to an instability of minkowski space.   however, all these instantons must be defined by introducing a constraint into the path integral, which is then integrated over.   i show that with a careful definition these instantons do not possess a negative mode.   infinite flat space is therefore stable against decay via singular instantons.   psfig.tex    @xmath0 ) @xmath1 ]  s   .2 in
this paper reports maps of the cd galaxy in the rich z=0.23 cluster abell 2390 at uv, , l@xmath0 and h@xmath0 wavelengths. spatially resolved uv and optical spectra were obtained with stis on the _ hubble space telescope _ ; the 2  wide slit was aligned close to the long axis and blue lane of the galaxy and includes all the inner bright features seen in wfpc2 images.   the l@xmath0 is seen in emission from several bright knots and over an extended region from 4  nw to 2  se of the nucleus.   three of these knots have detected uv continuum as well.   h@xmath0 images were obtained with _ osis _ at cfht ; both h@xmath0 and  show extended emission that roughly trace l@xmath0, primarily to the nw.   notable differences between the spatial distributions of h@xmath0, l@xmath0 and  emission and the blue knots in the galaxy may be the result of inhomogeneous dust extinction, or variations in ionisation.   the l@xmath0 emission velocities depend the uncertain identification with features in the undispersed images ; there is strong evidence for resolved emission knots to have large velocities, @xmath11000 km / s, indicative of infall.   the l@xmath0 spectrum shows a sharp cutoff which may be due to absorption ; we entertain the possibility that this edge is due to an shell of absorbing gas, outflowing at @xmath25000 km / s.
new data on proton and pion production in p+c interactions from the cern ps and sps accelerators are used in conjunction with other available data sets to perform a comprehensive survey of backward hadronic cross sections.   this survey covers the complete backward hemisphere in the range of lab angles from 10 to 180 degrees, from 0.2 to 1.4  gev / c in lab momentum and from 1 to 400  gev / c in projectile momentum. using the constraints of continuity and smoothness of the angular, momentum and energy dependences a consistent description of the inclusive cross sections   is established which allows the control of the internal consistency of the nineteen available data sets.   o.  chvala@xmath0, h.  g.  fischer@xmath1, m.  makariev@xmath2, a.  rybicki@xmath3, d.  varga@xmath4, s.  wenig@xmath5    @xmath4etvs lornd university, budapest, hungary + @xmath3h.   niewodniczaski institute of nuclear physics, polish academy of sciences, cracow, poland + @xmath5cern, geneva, switzerland + @xmath6charles university, faculty of mathematics and physics, institute of particle and nuclear physics, prague, czech republic + @xmath2institute for nuclear research and nuclear energy, bas, sofia, bulgaria + @xmath7now at university of tennessee, knoxville, tn, usa +
we introduce a set of bell inequalities for a three - qubit system. each inequality within this set   is violated by all generalized ghz states.   more entangled a generalized ghz state is, more will be the violation.   certain inequalities within this set are violated by pure biseparable states.   we also provide numerical evidence that at least one of these bell inequalities is violated by a pure genuinely entangled state.   these bell inequalities can distinguish between separable, biseparable and genuinely entangled pure three - qubit states.   we also generalize this set to @xmath0-qubit systems and may be suitable to characterize the entanglement of @xmath0-qubit pure states.
we develop a phenomenological model of superconductivity near a domain wall in a ferromagnet.   in addition to the electromagnetic interaction of the order parameter with the ferromagnetic magnetization, we take into account the possibility of a local enhancement or suppression of superconducting pairing in the vicinity of the wall, and also a non - perfect transparency of the wall to electrons. it is found that the critical temperature of superconductivity near the domain wall might be substantially higher than in the bulk.
the susceptible - infected - susceptible ( sis ) model is one of the simplest memoryless system for describing information / epidemic spreading phenomena with competing creation and spontaneous annihilation reactions.   the effect of quenched disorder on the dynamical behavior has recently been compared to quenched mean - field ( qmf ) approximations in scale - free networks.   qmf can take into account topological heterogeneity and clustering effects of the activity in the steady state by spectral decomposition analysis of the adjacency matrix.   therefore, it can provide predictions on possible rare - region effects, thus on the occurrence of slow dynamics.   i compare qmf results of sis with simulations on various large dimensional graphs.   in particular, i show that for erds - rnyi graphs this method predicts correctly the epidemic threshold and the rare - region effects.   griffiths phases emerge if the graph is fragmented or if we apply strong, exponentially suppressing weighting scheme on the edges.   the latter model describes the connection time distributions in the face - to - face experiments. in case of generalized barabsi - albert type of networks with aging connections strong rare - region effects and numerical evidence for griffiths phase dynamics   are shown.
we create collectively jammed ( cj ) packings of @xmath0-@xmath0 bidisperse mixtures of smooth disks in 2d using an algorithm in which we successively compress or expand soft particles and minimize the total energy at each step until the particles are just at contact.   we focus on small systems in 2d and thus are able to find nearly all of the collectively jammed states at each system size.   we decompose the probability @xmath1 for obtaining a collectively jammed state at a particular packing fraction @xmath2 into two composite functions : 1 ) the density of cj packing fractions @xmath3, which only depends on geometry and 2 ) the frequency distribution @xmath4, which depends on the particular algorithm used to create them.   we find that the function @xmath3 is sharply peaked and that @xmath4 depends exponentially on @xmath2.   we predict that in the infinite system - size limit the behavior of @xmath1 in these systems is controlled by the density of cj packing fractions  not the frequency distribution.   these results suggest that the location of the peak in @xmath1 when @xmath5 can be used as a protocol - independent definition of random close packing.
in the minimal supersymmetric standard model ( mssm ) with three generations of fermions, there is a stringent upper bound on the mass of the lightest neutral higgs @xmath0, and the mass of the charged higgs @xmath1, must be close ( within tens of gev ) to the heavier neutral higgs, @xmath2, and the pseudoscalar higgs @xmath3. in this brief report  , we show that in the four generation mssm, the upper bound on the @xmath0 mass is much higher, as high as 400 gev, and @xmath1 is generally much heavier than the @xmath3, allowing the @xmath4 decay, potentially changing search strategies for both the charged higgs and the pseudoscalar.   the @xmath2 mass, on the other hand, remains within tens of gev of the charged higgs mass.
this paper addresses the problem of determining the symmetries of a plane or space curve defined by a rational parametrization.   we provide effective methods to compute the involution and rotation symmetries for the planar case. as for space curves,   our method finds the involutions in all cases, and all the rotation symmetries in the particular case of pythagorean - hodograph curves.   our algorithms solve these problems without converting to implicit form. instead, we make use of a relationship between two proper parametrizations of the same curve, which leads to algorithms that involve only univariate polynomials.   these algorithms have been implemented and tested in the  system.
we compute the limit shape for several classes of restricted integer partitions, where the restrictions are placed on the part sizes rather than the multiplicities.   our approach utilizes certain classes of bijections which map limit shapes continuously in the plane.   we start with bijections outlined in  @xcite, and extend them to include limit shapes with different scaling functions.
star has performed a correlation analyses of pion - kaon and pion - proton pairs for @xmath0 and @xmath1 and kaon - proton, proton - lambda and pion - cascade pairs for auau collisions @xmath1.   they show that average emission space - time points of pions, kaons and protons are not the same.   these asymmetries are interpreted as a consequence of transverse radial expansion of the system ; emission time differences explain only part of the asymmetry.   therefore our measurements independently confirm the existence of transverse radial flow.   furthermore, correlations of strange hyperons is investigated by performing proton - lambda and pion - cascade analyses, giving estimates of source size at high @xmath2.   the strong interaction potential between ( anti-)proton and lambda as well as kaon and proton is investigated.   one of the main areas of interest in studying relativistic heavy - ion collisions is the collective behavior of matter, or flow  . non - identical particle correlations  @xcite have been proposed  @xcite as a measure of the transverse radial flow and asymmetries in particle emission from the expanding system produced in such collisions.
motivated by the finding that there is some biological universality in the relationship between school geometry and school biomass of various pelagic fishes in various conditions, i here establish a scaling law for school dimensions : the school diameter increases as a power - law function of school biomass.   the power - law exponent is extracted through the data collapse, and is close to @xmath0.   this value of the exponent implies that the mean packing density decreases as the school biomass increases, and the packing structure displays a mass - fractal dimension of @xmath1. by exploiting an analogy between school geometry and polymer chain statistics,   i examine the behavioral algorithm governing the swollen conformation of large - sized schools of pelagics, and i explain the value of the exponent.    power - law scaling, data collapse, pelagic fish, school size, geometry
renormalization of non - magnetic impurity potential by strong electron correlation is investigated in detail.   we adopt the @xmath0-@xmath1-@xmath2-@xmath3 model and consider mainly a @xmath4-function impurity potential.   the variational monte carlo method shows that impurity potential scattering matrix elements between gutzwiller - projected quasi - particle excited states are as strongly renormalized as the hopping terms.   such renormalization is also seen by the bogoliubov - de gennes equation with an impurity, where the strong correlation is treated by a gutzwiller mean - field theory with local renormalization factors and local chemical potentials.   namely, the @xmath4-function potential is effectively weakened and broadened.   we emphasize the importance of including the local chemical potential, which is paid little attention to in the literature, by physical consideration of the doping dependence of a local hole density.   we also investigate effect of smooth impurity potential variation ; the strong correlation yields anticorrelation between the gap energy and the coherence peak height simultaneously with large gap distribution, which is consistent with the experiments.
in this paper, we study the weak convergence of the integrated periodogram indexed by classes of functions for linear processes with symmetric @xmath0-stable innovations. under suitable summability conditions on the series of the fourier coefficients of the index functions,   we show that the weak limits constitute @xmath0-stable processes which have representations as infinite fourier series with i.i.d.   @xmath0-stable coefficients.   the cases @xmath1 and @xmath2 are dealt with by rather different methods and under different assumptions on the classes of functions.   for example, in contrast to the case @xmath1, entropy conditions are needed for @xmath2 to ensure the tightness of the sequence of integrated periodograms indexed by functions.   the results of this paper are of additional interest since they provide limit results for infinite mean random quadratic forms with particular toeplitz coefficient matrices.   ,
extrinsic multiferroic hybrid structures consisting of ferromagnetic and ferroelectric layers elastically coupled to each other are promising due to their robust magnetoelectric effects even at room temperature. for a quantitative analysis of these magnetoelectric effects, a detailed knowledge of the piezoelectric and magnetoelastic behavior of both constituents as well as   their mutual elastic coupling is mandatory.   we here report on a theoretical and experimental study of the magnetic behavior of batio@xmath0-based extrinsic multiferroic structures.   an excellent agreement between molecular dynamics simulations and the experiments was found for fe@xmath1co@xmath1/batio@xmath0 and ni / batio@xmath0 hybrid structures.   this demonstrates that the magnetic behavior of extrinsic multiferroic hybrid structures can be determined by means of ab - initio calculations, allowing for the design of novel multiferroic hybrids.
we simulate su(2 ) gauge theory at temperatures ranging from slightly below @xmath0 to roughly @xmath1 for two different values of the gauge coupling. using a histogram method  , we extract the effective potential for the polyakov loop and for the phases of the eigenvalues of the thermal wilson loop, in both the fundamental and adjoint representations.   we show that the classical potential of the fundamental loop can be parametrized within a simple model which includes a vandermonde potential and terms linear and quadratic in the polyakov loop.   we discuss how parametrizations for the other cases can be obtained from this model.
we investigate the interaction between h - dibaryons employing a quark cluster model with a one - gluon - exchange potential and an effective meson exchange potential ( emep ).   a deeply - bound state of two h - dibaryons due to the medium range attraction of the emep is obtained.   the bound h   h system has a size of about 0.8 @xmath0 0.9 fm because of the short - range repulsion generated by the color - magnetic interaction and the pauli principle.
let @xmath0 be a stationary sequence  . given @xmath1 $ ] moments and a mild weak dependence condition, we show a berry  esseen theorem with optimal rate @xmath2. for @xmath3, we also show a convergence rate of @xmath4 in @xmath5-norm, where @xmath6.   up to @xmath7 factors, we also obtain nonuniform rates for any @xmath8.   this leads to new optimal results for many linear and nonlinear processes from the time series literature, but also includes examples from dynamical system theory.   the proofs are based on a hybrid method of characteristic functions, coupling and conditioning arguments and ideal metrics.
transient radio emission from x - ray binaries is associated with synchrotron emission from collimated jets that escape the system, and accreting millisecond x - ray pulsars ( amxps ) are no exception.   although jets from black hole x - ray binaries are well - studied, those from neutron star systems appear much fainter, for reasons yet uncertain.   jets are usually undetectable at higher frequencies because of the relative brightness of other components such as the accretion disc.   amxps generally have small orbital separations compared with other x - ray binaries and as such their discs are relatively faint. here  , i present data that imply jets in fact dominate the radio - to - optical spectrum of outbursting amxps.   they therefore may provide the best opportunity to study the behaviour of jets produced by accreting neutron stars, and compare them to those produced by black hole systems.   address = astronomical institute ` anton pannekoek ', university of amsterdam, kruislaan 403, 1098 sj amsterdam, the netherlands, email=d.m.russell@uva.nl     address = school of physics & astronomy, university of southampton, southampton, so17 1bj, uk     address = sron, netherlands institute for space research, sorbonnelaan 2, 3584 ca utrecht, netherlands, altaddress = harvard - smithsonian center for astrophysics, 60 garden street, cambridge, ma 02138, usa     address = astronomical institute ` anton pannekoek ', university of amsterdam, kruislaan 403, 1098 sj amsterdam, the netherlands
in the classical knot theory there is a well - known notion of descending diagram. from an arbitrary diagram   one can easily obtain, by some crossing changes, a descending diagram which is a diagram of the unknot or unlink. in this paper   the notion of descending diagram for knots and links in @xmath0 is extended to the case of nonoriented knots and links in the projective space.   it is also shown that this notion can not be extended to oriented links.
this paper provides a solution to a critical issue in large - scale multi - user multiple - input multiple - output ( mu - mimo ) communication systems : how to estimate the signal - to - interference - plus - noise - ratios ( sinrs ) and their expectations in mu - mimo mode at the base station ( bs ) side when only the channel quality information ( cqi ) in single - user mimo ( su - mimo ) mode and non - ideal channel state information ( csi ) are known?   a solution to this problem would be very beneficial for the bs to predict the capacity of mu - mimo and choose the proper modulation and channel coding for mu - mimo. to that end  , this paper derives a normalized volume formula of a hyperball based on the probability density function of the canonical angle between any two points in a complex grassmann manifold, and shows that this formula provides a solution to the aforementioned issue.   it enables the capability of a bs to predict the capacity loss due to non - ideal csi, group users in mu - mimo mode, choose the proper modulation and channel coding, and adaptively switch between su - mimo and mu - mimo modes, as well as between conjugate beamforming ( cb ) and zero - forcing ( zf ) precoding.   numerical results are provided to verify the validity and accuracy of the solution.   complex grassmann manifold, hyperball, mu - mimo, non - ideal csi, normalized volume formula, sinr estimation.
the berry phase has found applications in building topological order parameters for certain condensed matter systems.   the question whether some geometric phase for mixed states can serve the same purpose has been raised, and proposals are on the table.   we analyze the intricate behaviour of uhlmann s geometric phase in the kitaev chain at finite temperature, and then argue that it captures quite different physics from that intended.   we also analyze the behaviour of a geometric phase introduced in the context of interferometry. for the kitaev chain  , this phase closely mirrors that of the berry phase, and we argue that it merits further investigation.
the emission spectra of tev blazars extend up to tens of tev and the emission mechanism of the tev @xmath0-rays is explained by synchrotron self - compton scattering in leptonic models. in these models   the time variabilities of x - rays and tev @xmath0-rays are correlated.   however, recent observations of 1es 1959 + 650 and mrk 421 have found the `` orphan '' tev @xmath0-ray flares, i.e., tev @xmath0-ray flares without simultaneous x - ray flares. in this paper   we propose a model for the `` orphan '' tev @xmath0-ray flares, employing an inhomogeneous leptonic jet model. after a primary flare that accompanies flare - up both in x - rays and tev @xmath0-rays, radiation propagates in various directions in the comoving frame of the jet.   when a dense region in the jet receives the radiation, x - rays are scattered by relativistic electrons / positrons to become tev @xmath0-rays.   these @xmath0-ray photons are observed as an `` orphan '' tev @xmath0-ray flare.   the observed delay time between the primary and `` orphan '' flares is about two weeks and this is accounted for in our model for parameters such as @xmath1, @xmath2 cm, @xmath3, and @xmath4, where @xmath5 is the bulk lorentz factor of the jet, @xmath6 is the distance between the central black hole and the primary flare site, @xmath7 is the angle between the jet axis and the direction of the motion of the dense region that scatters incoming x - rays produced by the primary flare, and @xmath8 is the angle between the jet axis
we consider a communication scenario where a source communicates with a destination over a directed layered relay network.   each relay performs analog network coding where it scales and forwards the signals received at its input. in this scenario  , we address the question : what portion of the maximum end - to - end achievable rate can be maintained if only a fraction of relay nodes available at each layer are used?   we consider, in particular, the gaussian diamond network ( layered network with a single layer of relay nodes ) and a class of symmetric layered networks. for these networks we show that each relay layer increases the additive gap between the optimal analog network coding performance with and without network simplification ( using @xmath0 instead of @xmath1 relays in each layer, @xmath2 ) by no more than @xmath3 bits and the corresponding multiplicative gap by no more than a factor of @xmath4, asymptotically ( in source power ). to the best of our knowledge  , this work offers the first characterization of the performance of network simplification in general layered amplify - and - forward relay networks.   further, unlike most of the current approximation results that attempt to bound optimal rates either within an additive gap or a multiplicative gap, our results suggest a new rate approximation scheme that allows for the simultaneous computation of additive and multiplicative gaps.
we analyze the @xmath0 decays, which have small or even vanishing branching ratios in naive factorization assumption ( fa ).   we calculate nonfactorizable corrections to fa in the perturbative qcd approach based on @xmath1 factorization theorem.   the charmonium distribution amplitudes are inferred from the non - relativistic heavy quarkonium wave functions.   it is found that the nonfactorizable contributions enhance the branching ratios and generate the relative phases among helicity amplitudes of the above modes.   most of the observed branching ratios, polarization fractions, and relative phases, except those of @xmath2, are explained.   our predictions for the @xmath3 decays can be compared with future data  .    23.2 cm 17.0 cm = -1.5 cm = -1 cm = 0.2 cm    0.5 cm    *.3 cm chuan - hung chen@xmath4 and hsiang - nan li@xmath5 *    2.0 cm    1.0 cm    2.0 cm
employing first - principles calculations we study the structural, electronic and magnetic properties of the [ sc@xmath0v@xmath1c and [ sc@xmath0v@xmath1si alloys. in their equilibrium rocksalt structure   all alloys are non - magnetic.   the zincblende and wurtzite structures are degenerated with respect to the total energy. for all concentrations the alloys in these lattice structures are half - metallic with the gap located in the spin - down band.   the total spin moment follows the slater - pauling behavior varying linearly between the -1 @xmath2 of the perfect scc and scsi alloys and the + 1 @xmath2 of the perfect vc and vsi alloys. for the intermediate concentrations v and sc atoms   have antiparallel spin magnetic moments and the compounds are half - metallic ferrimagnets. at the critical concentration, both c and si alloys present zero total spin - magnetic moment but   the c - based alloy shows a semiconducting behavior contrary to the si - based alloys which is a half - metallic antiferromagnet  .    electronic structure, half - metals, ferrimagnets    75.47.np, 75.50.cc, 75.30.et
the spectral energy distribution of the proto - galaxy candidate ms1512-cb58 at @xmath0 discovered by yee et al.   ( 1996 ) is presented.   photometry in seven bands ranging from @xmath1 to @xmath2@xmath3 ( 13006000   rest wavelength ) are fitted with population synthesis models from bruzual & charlot ( 1993 ).   the data confirm a very young age for this galaxy, in agreement with ages estimated from preliminary  p - cygni profile modeling.   single - burst models with ages greater than about 20 myr can be discarded at the 99% confidence level, and continuous star formation models with ages greater than about 35 myr can be discarded at the 95% confidence level.   the spectral energy distribution is most consistent with a continuous star formation model of about 1020 myr, with reddening of @xmath4.   no evidence for an older population of stars is seen, but the possibility of an older population with as much as 90% of the galaxy mass can not be ruled out. we discuss the possible ramifications of a non - standard imf and gravitational lensing on the galaxy s age and mass.   = cmr10
modal logics are widely used in computer science.   the complexity of modal satisfiability problems has been investigated since the 1970s, usually proving results on a case - by - case basis.   we prove a very general classification for a wide class of relevant logics : many important subclasses of modal logics can be obtained by restricting the allowed models with first - order horn formulas.   we show that the satisfiability problem for each of these logics is either @xmath0-complete or @xmath1-hard, and exhibit a simple classification criterion.   further, we prove matching @xmath1  upper bounds for many of the @xmath1-hard logics.
we investigate the in - plane spin relaxation of electrons due to the dyakonov - perel and elliot - yafet mechanisms including the intra- and inter - valley processes in monolayer mos@xmath0.   we construct the effective hamiltonian for the conduction band using the lwdin partition method from the anisotropic two - band hamiltonian with the intrinsic spin - orbit coupling of the conduction band included.   the spin - orbit coupling of the conduction band induces the intra- and inter - valley dyakonov - perel spin relaxation.   in addition, the elliot - yafet spin relaxation also takes place due to the interband spin mixing.   we find that the dyakonov - perel mechanism dominates the in - plane spin relaxation. in the framework of this mechanism,   the intravalley process is shown to play a more important role at low temperature whereas the intervalley one becomes more important at high temperature. at the temperature in between, the leading process of the in - plane spin relaxation changes from the intervalley to intravalley one as the electron density increases.   moreover, we find that the intravalley process is dominated by the electron - electron coulomb scattering even with high impurity density since the dominant term in the spin - orbit coupling is isotropic, which does not lead to the spin relaxation together with the electron - impurity scattering.   this is very different from the previous studies in semiconductors and graphene.
we study the prospects of probing large extra dimension model at the lhc through neutral triple gauge boson production processes. in theories with extra dimensions these processes result from the exchange of a tower of massive graviton modes between the sm particles.   we consider @xmath0, @xmath1, @xmath2 and @xmath3 production processes, and present our results for various kinematic distributions at the lhc for @xmath4 tev.   desy 11 - 229 + sfb / cpp-11 - 72 + lpn11 - 68     + m.  c.  kumar@xmath5 prakash mathews@xmath6 v.  ravindran@xmath7 satyajit seth@xmath6 + @xmath8 deutsches elektronen - synchrotron desy, platanenallee 6, d-15738 zeuthen, germany + @xmath9 saha institute of nuclear physics, 1/af bidhan nagar, kolkata 700 064, india + @xmath10 regional centre for accelerator - based particle physics + harish - chandra research institute, chhatnag road, jhunsi, + allahabad 211 019, india    pacs number : 12.38.bx, 13.85.qk, 14.70.hp, 14.80.rt
we report a giant metrewave radio telescope ( gmrt ) search for hi 21 cm emission from a large sample of star - forming galaxies at @xmath0, lying in sub - fields of the deep2 redshift survey.   the search was carried out by co - adding ( `` stacking '' ) the hi 21 cm emission spectra of 857 galaxies, after shifting each galaxy s hi 21 cm spectrum to its rest frame.   we obtain the @xmath1 upper limit s@xmath2jy on the average hi 21 cm flux density of the 857  galaxies, at a velocity resolution of @xmath3  km  s@xmath4.   this yields the @xmath1 constraint m@xmath5^{1/2 } \textrm{m}_\odot$ ] on the average hi mass of the 857 stacked galaxies, the first direct constraint on the atomic gas mass of galaxies at @xmath6.   the implied limit on the average atomic gas mass fraction ( relative to stars ) is @xmath7, comparable to the cold molecular gas mass fraction in similar star - forming galaxies at these redshifts.   we find that the cosmological mass density of neutral atomic gas in massive star - forming galaxies at @xmath8 is @xmath9, significantly lower than @xmath10 estimates in both galaxies in the local universe and damped lyman-@xmath11 absorbers at @xmath12.   massive blue star - forming galaxies thus do not appear to dominate the neutral atomic gas content of the universe at @xmath8.
spain was a scientifically backward country in the early 19th - century.   the causes were various political events, the war of independence, and the reign of fernando vii.   the introduction of contemporary physics into textbooks was therefore a slow process.   an analysis of the contents of 19th - century spanish textbooks is here presented, centred on imponderable fluids, the concept of energy, the mechanical theory of heat, and the kinetic theory of gases.   = 10000 = 10000
simple broadband microwave interconnects are needed for increasing the size of focal plane heterodyne radiometer arrays.   we have measured loss and cross - talk for arrays of microstrip transmission lines in flex circuit technology at 297 and 77k, finding good performance to at least 20ghz.   the dielectric constant of kapton substrates changes very little from 297 to 77k, and the electrical loss drops.   the small cross - sectional area of metal in a printed circuit structure yields overall thermal conductivities similar to stainless steel coaxial cable.   operationally, the main performance tradeoffs are between crosstalk and thermal conductivity.   we tested a patterned ground plane to reduce heat flux.
we report the detection of the linear radical hc@xmath0n in the c - rich envelope of irc+10216.   after hccn @xcite, hc@xmath0n is the second member of the allenic chain family hc@xmath1n observed in space.   the column density of hc@xmath0n is found to be 1.5 10@xmath2 @xmath3.   the abundance ratio hc@xmath4n / hc@xmath0n is 9, a factor of two larger than the decrement observed for the cyanopolyynes ( hc@xmath5n / hc@xmath6n ).   linear hc@xmath0n has a @xmath7 electronic ground state and is one of the 3 low - energy isomeric forms of this molecule.   we have searched for the bent and ringed hc@xmath0n isomers, but could only derive an upper limit to their column densities @xmath8 3 10@xmath2 @xmath3 ( at 3-@xmath9 ).
we derive new constraints set by snia experiments ( ` gold'data sample of riess   _ et al.   _ ), x - ray galaxy cluster data ( allen _ et al.   _ _ chandra _ measurements of the x - ray gas mass fraction in 26 clusters ), large scale structure ( sloan digital sky survey spectrum ) and cosmic microwave background ( wmap ) on the quartessence chaplygin model.   we consider both adiabatic perturbations and intrinsic non - adiabatic perturbations such that the effective sound speed vanishes ( _ silent chaplygin _ ). we show   that for the adiabatic case, only models with equation of state parameter @xmath0 are allowed : this means that the allowed models are very close to @xmath1cdm. in   the _ silent _ case, however, the results are consistent with observations in a much broader range, @xmath2.
we introduce the concept of distillability sudden death, i.e., free entangled states can evolve into non - distillable ( bound entangled or separable ) states in finite time under local noise.   we describe the phenomenon through a specific model of local dephasing noise and compare the behavior of states in terms of the bures fidelity.   then we propose a few methods to avoid distillability sudden death of states under ( general ) local dephasing noise, so that free entangled states can be robust against decoherence.   moreover, we find that bound entangled states are unstable in the limit of infinite time.
we demonstrate that the modulation instability of the zone boundary mode in a finite ( periodic ) fermi - pasta - ulam chain is the necessary but not sufficient condition for the efficient energy transfer by localized excitations.   this transfer results from the exclusion of complete energy exchange between spatially different parts of the chain, and the excitation level corresponding to that turns out to be twice more than threshold of zone boundary mode s instability. to obtain this result one needs in far going extension of the beating concept to a wide class of finite oscillatory chains. in turn  , such an extension leads to description of energy exchange and transition to energy localization and transfer in terms of _   effective particles _ and _ limiting phase trajectories_. the effective particles appear naturally when the frequency spectrum crowding ensures the resonance interaction between zone boundary and two nearby nonlinear normal modes, but there are no additional resonances. we show that the limiting phase trajectories corresponding to the most intensive energy exchange between effective particles can be considered as an alternative to nonlinear normal modes, which describe the stationary process.
the surrogate data method is widely applied as a data dependent technique to test observed time series against a barrage of hypotheses. however, often the hypotheses one is able to address are not those of greatest interest, particularly for system known to be nonlinear. in the review we focus on techniques which overcome this shortcoming.   we summarize a number of recently developed surrogate data methods.   while our review of surrogate methods is not exhaustive, we do focus on methods which may be applied to experimental, and potentially nonlinear, data. in each case  , the hypothesis being tested is one of the interests to the experimental scientist.
a two phase cascade, lucifer ii@xcite, developed for the treatment of ultra high energy ion - ion collisions is applied to the production of strangeness at sps energies @xmath0.   this simulation is able to simultaneously describe both hard processes such as drell - yan and slower, soft processes such as the production of light mesons, including strange mesons, by separating the dynamics into two steps, a fast cascade involving only nucleons in the original colliding relativistic ions followed, after an appropriate delay, by multiscattering of the resulting excited baryons and mesons produced virtually in the first step.   no energy loss can take place in the short time interval over which the first cascade takes place.   the chief result is a reconciliation of the important drell - yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the cern sps.   a byproduct, obtained here in preliminary calculations, is a description of strangeness production in the collision of massive ions.
we investigate a prototypical agent - based model, the naming game, on two - dimensional random geometric networks.   the naming game [ a. baronchelli et al., j. stat. mech. : theory exp.   ( 2006 ) p06014. ] is a minimal model, employing local communications that captures the emergence of shared communication schemes ( languages ) in a population of autonomous semiotic agents.   implementing the naming games with local broadcasts on random geometric graphs, serves as a model for agreement dynamics in large - scale, autonomously operating wireless sensor networks.   further, it captures essential features of the scaling properties of the agreement process for spatially - embedded autonomous agents. among the relevant observables capturing the temporal properties of the agreement process  , we investigate the cluster - size distribution and the distribution of the agreement times, both exhibiting dynamic scaling.   we also present results for the case when a small density of long - range communication links are added on top of the random geometric graph, resulting in a  small - world "- like network and yielding a significantly reduced time to reach global agreement.   we construct a finite - size scaling analysis for the agreement times in this case.
we use an effective qcd model ( ladder - qcd ) to explore the phase diagram for chiral symmetry breaking and restoration at finite temperature with different @xmath0 quark chemical potentials. in agreement with a recent investigation based on the nambu - jona - lasinio model, we find that a finite pion condensate shows up for high enough isospin chemical potential @xmath1. for small @xmath2   the phase diagram in the @xmath3 plane shows two first order transition lines and two critical ending points.
within the `` pseudo - dirac '' scenario for massive neutrinos the existence of sterile neutrinos which are almost degenerate in mass with the active ones is hypothesized.   the presence of these sterile neutrinos can affect the flavor composition of cosmic neutrinos arriving at earth after traveling large distances from astrophysical objects.   we examine the prospects of neutrino telescopes such as icecube to probe the very tiny mass squared differences @xmath0  ev@xmath1  ev@xmath2, by analyzing the ratio of @xmath3-track events to shower - like events. considering various sources of uncertainties which enter this analysis  , we examine the capability of neutrino telescopes to verify the validity of the pseudo - dirac neutrino scenario and especially to discriminate it from the conventional scenario with no sterile neutrino.   we also discuss the robustness of our results with respect to the uncertainties in the initial flavor ratio of neutrinos at the source.   pacs numbers : 14.60.pq ; 13.15.+g ; 95.85.ry    ipm / p-2009/039   +    * pseudo - dirac neutrino scenario : + cosmic neutrinos at neutrino telescopes * + * @xmath4 * + _ department of physics, sharif university of technology + p.o.box 11365 - 8639, tehran, iran _ + _ school of physics, institute for research in fundamental sciences ( ipm ) + p.o.box 19395 - 5531, tehran, iran _
we study thermodynamics of the 3d hubbard model at half filling on approach to the nel transition by means of large - scale unbiased diagrammatic determinant monte carlo simulations.   we obtain the transition temperature in the strongly correlated regime, as well as temperature dependence of energy, entropy, double occupancy, and the nearest - neighbor spin correlation function.   our results improve the accuracy of previous unbiased studies and present accurate benchmarks in the ongoing effort to realize the antiferromagnetic state of matter with ultracold atoms in optical lattices.
suppose we are given the free product v of a finite family of finite or countable sets.   we consider a transient random walk on the free product arising naturally from a convex combination of random walks on the free factors.   we prove the existence of the asymptotic entropy and present three different, equivalent formulas, which are derived by three different techniques.   in particular, we will show that the entropy is the rate of escape with respect to the greenian metric.   moreover, we link asymptotic entropy with the rate of escape and volume growth resulting in two inequalities.   lorenz a. gilch     graz university of technology + institut fr mathematische strukturtheorie ( math.   c ) + steyrergasse 30 + a-8010 graz + austria + email : gilch@tugraz.at + url : http://www.math.tugraz.at/@xmath0gilch/
we discuss an extension of the theory of _ spin - orbit pendulum _ phenomenon given in @xcite to relativistic approach.   it is done within the so called dirac oscillator.   our first results, focusing on circular wave packet motion have been published recently @xcite.   the scope of this paper is motion of a linear wave packet. in relativistic approach we found _ zitterbewegung _ in spin - orbit motion ( in dirac representation ) due to coupling to negative energy states.   this effect is washed out in the foldy - wouthuysen representation.   another important change with respect to non - relativistic case is the loss of periodicity.   the phenomenon reminds the time evolution of population inversion in jaynes - cummings model.
we carry out the harmonic analysis on four platonic spherical three - manifolds with different topologies. starting out from the homotopies ( _ everitt 2004 _  ), we convert them into deck operations, acting on the simply connected three - sphere as the cover, and obtain the corresponding variety of deck groups. for each topology  , the three - sphere is tiled into copies of a  fundamental domain under the corresponding deck group.   we employ the point symmetry of each platonic manifold to construct its fundamental domain as a  spherical orbifold.   while the three - sphere supports an  orthonormal complete basis for harmonic analysis formed by wigner polynomials, a given spherical orbifold leads to a  selection of a  specific subbasis.   the resulting selection rules find applications in cosmic topology, probed by the cosmic microwave background.
we present results from our ongoing spectroscopic search for giant planets within 1 au around a well - defined sample of metal - poor stars with hires on the keck 1 telescope.   we have achieved an rms radial velocity precision of @xmath0 m / s over a time - span of 1.5 years.   the data collected so far build toward evidence of the absence of very short - period ( @xmath1 month ) giant planets. however, about 7% of the stars in our sample exhibits velocity trends indicative of the existence of companions.   we place preliminary upper limits on the detectable companion mass as a function of orbital period, and compare them with the performance of esa s future space - borne high - precision astrometric observatory gaia.   
the elastic constant tensors for the hcp phases of three transition metals ( co, re, and fe ) are computed as functions of pressure using the linearized augmented plane wave method with both the local density and generalized gradient approximations.   spin - polarized states are found to be stable for co ( ferromagnetic ) and fe ( antiferromagnetic at low pressure ).   the elastic constants of co and re are compared to experimental measurements near ambient conditions and excellent agreement is found.   recent measurements of the lattice strain in high pressure experiments when interpreted in terms of elastic constants for re and fe are inconsistent with the calculated moduli.
we use an external spin as a dynamical probe of many body localization.   the probe spin is coupled to an interacting and disordered environment described by a heisenberg spin chain in a random field.   the spin - chain environment can be tuned between a thermalizing delocalized phase and non - thermalizing localized phase, both in its ground- and high - energy states.   we study the decoherence of the probe spin when it couples to the environment prepared in three states : the groundstate, the infinite temperature state and a high energy nel state. in the non - thermalizing many body localized regime,   the coherence shows scaling behaviour in the disorder strength.   the long - time dynamics of the probe spin shows a logarithmic dephasing in analogy with the logarithmic growth of entanglement entropy for a bi - partition of a many - body localized system. in summary  , we show that decoherence of the probe spin provides clear signatures of many - body localization.
we follow the structural evolution of star forming galaxies ( sfgs ) like the milky way by selecting progenitors to @xmath0 based on the stellar mass growth inferred from the evolution of the star forming sequence.   we select our sample from the 3d - hst survey, which utilizes spectroscopy from the _ hst _   wfc3 g141 near - ir grism and enables precise redshift measurements for our sample of sfgs.   structural properties are obtained from srsic profile fits to candels wfc3 imaging.   the progenitors of @xmath1 sfgs with stellar mass @xmath2  are typically half as massive at @xmath3.   this late - time stellar mass growth is consistent with recent studies that employ abundance matching techniques.   the descendant sfgs at @xmath4 have grown in half - light radius by a factor of @xmath5 since @xmath3.   the half - light radius grows with stellar mass as @xmath6.   while most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late - type galaxies.   some portion of this growth in the central regions is due to star formation as recent observations of h@xmath7 maps for sfgs at @xmath3 are found to be extended but centrally peaked. connecting our lookback study with galactic archeology,   we find the stellar mass surface density at @xmath8  kpc to have increased by a factor of @xmath9 since @xmath3, in good agreement with measurements derived for the solar neighborhood of the milky way.
the origin of a chemical reaction between two reactant atoms is associated to the activation energy, with the assumption that, high - energy collisions between these atoms, are the ones that overcome the activation energy. here,   we ( i ) show that a stronger attractive van der waals ( vdw ) and electron - ion coulomb interactions between two polarized atoms are responsible to initiate a chemical reaction, either before or after the collision.   we derive this stronger vdw attraction formula exactly using the quasi one - dimensional drude model within the ionization energy theory and the energy - level spacing renormalization group method. along the way, we ( ii ) expose the precise physical mechanism responsible for the existence of a stronger vdw interaction for both long and short distances, and also show how to technically avoid the electron - electron coulomb repulsion between polarized electrons from these two reactant atoms  . finally, we properly and correctly associate the existence of this stronger attraction to ramachandran s ` normal limits'( distance shorter than what is allowed by the standard vdw bond ) between chemically nonbonded atoms, setting the record straight.
in the last few years many globular clusters ( gcs ) have revealed complex color - magnitude diagrams, with the presence of multiple main sequences ( mss ), broaden or multiple sub - giant branches ( sgbs ) and ms turn offs, and broad or split red giant branches ( rgbs ). after a careful correction for differential reddening,   high accuracy photometry with the hubble space telescope presented in this paper reveals a broadened or even split sgb in five additional milky way gcs : ngc 362, ngc 5286, ngc 6656, ngc 6715, and ngc 7089.   in addition, we confirm ( with new and archival hst data ) the presence of a split sgb in 47tuc, ngc 1851, and ngc 6388.   the fraction of faint sgb stars with respect to the entire sgb population varies from one cluster to another and ranges from @xmath00.03 for ngc 362 to @xmath00.50 for ngc 6715.   the average magnitude difference between the bright sgb and the faint sgb is almost the same at different wavelengths.   this peculiarity is consistent with the presence of two groups of stars with either an age difference of about 1 - 2 gyrs, or a significant difference in their overall c+n+o content.
the emergence of the grid architecture and related tools will have a large impact in the operation and design of present and future large clusters.   we present here the ongoing efforts to equip the linux farm at the rhic computing facility with grid - like capabilities.
we review the main properties of shell models for magnetohydrodynamic ( mhd ) turbulence. after a brief account on shell models with nearest neighbour interactions,   the paper focuses on the most recent results concerning dynamical properties and intermittency of a model which is a generalization to mhd of the gledzer - yamada - okhitani ( goy ) model for hydrodynamic.   applications to astrophysical problems are also discussed.
we discuss physical implications of the explicit method in numerical analysis.   numerical methods have there own condition for causality, known as the courant - friedrichs - lewy condition.   it is proposed that numerical causality merges with physical causality as the grid interval size approaches zero.   we discuss the implications of this proposition on the numerical analysis of the wave equation.   we also show that, insisting on physical causality, the numerical analysis of schrodinger s equation implies that the minimum space interval should satisfy @xmath0, where @xmath1 is the reduced compton wavelength and @xmath2 is a constant of the order unity.   * numerical methods and causality in physics *    muhammad adeel ajaib     _ university of delaware, newark, de 19716, usa _
new physics beyond the electroweak scale may increase weak interaction cross sections beyond the standard model predictions.   such cross sections can be expected within theories that solve the hierarchy problem of known interactions with a unification scale in the tev range.   we derive constraints on these cross sections from the flux of neutrinos expected from cosmic ray interactions with the microwave background and the non - observation of horizontal air showers.   we also discuss how this limit can be improved by upcoming cosmic ray and neutrino experiments, and how the energy dependence of the new interactions can be probed by these experiments.
we present chandra x - ray monitoring of the m87 jet in 2002, which shows that the intensity of hst-1, an optical knot 0.8@xmath0 from the core, increased by a factor of two in 116 days and a factor of four in 2 yrs.   there was also a significant flux decrease over two months, with suggestive evidence for a softening of the spectrum. from this variability behavior, we argue that the bulk of the x - ray emission of hst-1 comes from synchrotron emission  . none of the other conceivable emission processes can match the range of observed characteristics. by estimating synchrotron model parameters for various bulk relativistic velocities,   we demonstrate that a model with a doppler factor @xmath1 in the range 2 to 5 fits our preliminary estimates of light travel time and synchrotron loss timescales.
we propose a fermion chern - simons field theory describing two - dimensional electrons in the lowest landau level.   this theory is constructed with a complete set of states, and the lowest landau level constraint is enforced through a @xmath0-functional described by an auxiliary field @xmath1. unlike the field theory constructed directly with the states in the lowest landau level, this theory allows one utilizing the physical picture of  composite fermion " to study the fractional quantum hall states by mapping them onto certain integer quantum hall states ; but unlike it in the unconstrained theory, such a mapping is sensible only when interactions between electrons are present. an  effective mass ", which characterizes the scale of low energy excitations in the fractional quantum hall systems, emerges naturally from our theory.   we study a gaussian effective theory and interpret physically the dressed stationary point equation for @xmath1 as an equation for the  mass renormalization " of composite fermions.
we report the detection of h@xmath0 emission in the t dwarf ( methane brown dwarf ) 2massw j1237392 + 652615 over three days using the keck low resolution imaging spectrograph.   the measured line flux, log(l@xmath1/l@xmath2 ) = @xmath34.3, is roughly consistent with early m dwarf activity levels and inconsistent with decreasing activity trends in late m and l dwarfs.   similar emission is not seen in two other t dwarfs.   we speculate on several mechanisms that may be responsible for emission, including a strong magnetic field, continuous flaring, acoustic heat generation, and a close ( @xmath4 @xmath5 4 - 20 r@xmath6 ) interacting binary, with the cooler component overflowing its roche lobe.   we suggest that the m9.5ve pc 0025 + 0447 could be a warm analogue to 2mass j1237 + 65, and may be powered by the latter mechanism.
van der waals - casimir dispersion interactions between two apposed graphene layers, a graphene layer and a substrate, and in a multilamellar graphene system are analyzed within the framework of the lifshitz theory.   this formulation hinges on a known form of the dielectric response function of an undoped or doped graphene sheet, assumed to be of a random phase approximation form. in the geometry of two apposed layers the separation dependence of the van der waals - casimir interaction for both types of graphene sheets   is determined and compared with some well known limiting cases. in a multilamellar array the many - body effects are quantified and shown to increase the magnitude of the van der waals - casimir interactions.
a susceptibility function @xmath0 is introduced to quantify some aspects of the intermittent stick - slip dynamics of a rough metallic cylinder of length @xmath1 on a rough metallic incline submitted to small controlled perturbations and maintained below the angle of repose.   this problem is studied from the experimental point of view and the observed power - law behavior of @xmath0 is justified through the use of a general class of scaling hypotheses.   fluctuation phenomena, fractal surfaces, nonstationary behavior, scaling    05.40.-a, 05.45.df, 05.70.np, 68.35.rh
cavity quantum electrodynamic schemes for quantum gates are amongst the earliest quantum computing proposals. despite continued progress and the recent demonstration of photon blockade, there are still issues with optimal coupling and gate operation involving high - quality cavities. here we show that dynamic cavity control allows for scalable cavity - qed based quantum gates using the full cavity bandwidth.   this technique allows an order of magnitude increase in operating speed, and two orders reduction in cavity @xmath0, over passive systems.   our method exploits stark shift based @xmath0 switching, and is ideally suited to solid - state integrated optical approaches to quantum computing.
at the threshold of black hole formation in the gravitational collapse of a scalar field a naked singularity is formed through a universal critical solution that is discretely self - similar.   we study the global spacetime structure of this solution.   it is spherically symmetric, discretely self - similar, regular at the center to the past of the singularity, and regular at the past lightcone of the singularity. at the future lightcone of the singularity, which is also a cauchy horizon,   the curvature is finite and continuous but not differentiable. to the future of the cauchy horizon   the solution is not unique, but depends on a free function ( the null data coming out of the naked singularity ).   there is a unique continuation with a regular center ( which is self - similar ).   all other self - similar continuations have a central timelike singularity with negative mass.
we study the haldane - hubbard model by exact renormalization group techniques.   we analytically construct the topological phase diagram, for weak interactions.   we predict that many - body interactions induce a shift of the transition line : in particular, repulsive interactions enlarge the topologically non - trivial region.   the presence of new intermediate phases, absent in the non interacting case, is rigorously excluded at weak coupling. despite the non - trivial renormalization of the wave function and of the fermi velocity,   the conductivity is universal : at the renormalized critical line, both the discontinuity of the transverse conductivity and the longitudinal conductivity are independent of the interaction, thanks to remarkable cancellations due to lattice ward identities.   in contrast to the quantization of the transverse conductivity, the universality of the longitudinal conductivity can not be explained via topological arguments.
we present the first observations of magnetic cataclysmic variables with the spitzer space telescope.   we used the infrared array camera to obtain photometry of the polars ef eri, gg leo, v347 pav, and rx j0154.0 - 5947 at 3.6, 4.5, 5.8, and 8.0 @xmath0 m. in all of our targets, we detect excess mid - infrared emission over that expected from the component stars alone.   we explore the origin of this ir excess by examining bremsstrahlung, cyclotron emission, circumbinary dust, and l / t brown dwarf secondary stars. bremsstrahlung and cyclotron emission appear unlikely to be significant contributors to the observed fluxes. at present,   the most likely candidate for the excess emission is dust that is probably located in a circumbinary disk with an inner temperature near 800 k. however, a simple dust disk plus any reasonable low mass or brown dwarf - like secondary star is unable to fully explain the observed flux densities in the 38 @xmath0 m region.
the notion of instability of a turbulent flow is introduced in the case of a von krmn flow thanks to the monitoring of the spatio - temporal spectrum of the velocity fluctuations, combined with projection onto suitable beltrami modes.   it is shown that the large scale coherent fluctuations of the flow obeys a sequence of eckhaus instabilities when the reynolds number @xmath0 is varied from @xmath1 to @xmath2.   this sequence results in modulations of increasing azimuthal wavenumber. the basic state is the laminar or time - averaged flow at an arbitrary @xmath0, which is axi - symmetric, _   i.e. _ with a @xmath3 azimuthal wavenumber. increasing @xmath0 leads to non - axisymmetric modulations with increasing azimuthal wavenumber from @xmath4 to @xmath5.   these modulations are found to rotate in the azimuthal direction.   however no clear rotation frequency can be established until @xmath6. above  , they become periodic with an increasing frequency.   we finally show that these modulations are connected with the coherent structures of the mixing shear layer.   the implication of these findings for the turbulence parametrization is discussed. especially, they may explain why simple eddy viscosity models are able to capture complex turbulent flow dynamics.
large scale, deep survey missions such as gaia will collect enormous amounts of data on a significant fraction of the stellar content of our galaxy.   these missions will require a careful optimisation of their observational systems in order to maximise their scientific return, and will require reliable and automated techniques for parametrizing the very large number of stars detected. to address these two problems, i investigate the precision to which the three principal stellar parameters (,, )  can be determined as a function of spectral resolution and signal - to - noise ( snr ) ratio, using a large grid of synthetic spectra.   the parametrization technique is a neural network, which is shown to provide an accurate three - dimensional physical parametrization of stellar spectra across a wide range of parameters.   it is found that even at low resolution ( 50100  fwhm ) and snr ( 510 per resolution element ), and  can be determined to 1% and 0.2 dex respectively across a large range of temperatures ( 400030000k ) and metallicities ( @xmath03.0 to @xmath11.0 dex ), and that  is measurable to @xmath2 dex for stars earlier than solar.   the accuracy of the results is probably limited by the finite parameter sampling of the data grid.   the ability of medium band filter systems ( with 1015 filters ) for determining stellar parameters is also investigated.   although easier to implement in a unpointed survey, it is found that they are only competitive at higher snrs ( @xmath3 ).
the thermal properties of the three - dimensional dirac oscillator are considered.   the canonical partition function is determined, and the high - temperature limit is assessed.   the degeneracy of energy levels and their physical implications on the main thermodynamic functions are analyzed, revealing that these functions assume values greater than the one - dimensional case.   so that at high temperatures, the limit value of the specific heat is three times bigger.
this paper investigates the problem of decomposition with respect to outputs for boolean control networks ( bcns ).   first, with the linear expression of bcns and the matrix semi - tensor product, some algebraic equivalent conditions for the decomposition are obtained.   second, a necessary and sufficient graphical condition for the decomposition with respect to outputs is given.   third, an effective method is proposed to reduce the computational burden in the realization of the decomposition.   finally, some examples are addressed to validate the effectiveness of the proposed method.   ,    boolean control networks, decomposition with respect to outputs, semi - tensor product, observability.
torque fluctuations due to magnetorotational turbulence in proto - planetary disks may greatly influence the migration patterns and survival probabilities of nascent planets. provided that the turbulence is a stationary stochastic process with finite amplitude and correlation time  , the resulting diffusive migration can be described with a fokker - planck equation, which we reduce to an advection - diffusion equation.   we calibrate the coefficients with existing turbulent - disk simulations and mean - migration estimates, and solve the equation both analytically and numerically.   diffusion tends to dominate over advection for planets of low - mass and those in the outer regions of proto - planetary disks, whether they are described by the minimum mass solar nebula ( mmsn ) or by t - tauri alpha disks.   diffusion systematically reduces the lifetime of most planets, yet it allows a declining fraction of them to survive for extended periods of time at large radii.   mean planet lifetimes can even be formally infinite ( e.g. in an infinite steady mmsn ), though median lifetimes are always finite.   surviving planets may linger near specific radii where the combined effects of advection and diffusion are minimized, or at large radii, depending on model specifics.   the stochastic nature of migration in turbulent disks challenges deterministic planet formation scenarios and suggests instead that a wide variety of planetary outcomes are possible from similar initial conditions.   this would contribute to the diversity of ( extrasolar ) planetary systems.
3c  66a was monitored by the batc ( beijing - arizona - taipei - connecticut ) telescope from 2005 to 2008, 1994 observations were obtained on 89 nights. detailed research and analysis was performed on these observations in this paper.   a long term burst occurred in the whole light curve.   no intra - day variability was claimed in our campaign by intra - night light curve analysis.   time lag of shorter wavelenth preceding longer wavelength was shown by correlation analysis.   the results showed that the optical spectral shape turned flatter when the source brightened, and the spectral variability indicator was bigger on shorter time - scale as determined by the color indices variation analysis.
the polynomial eigenvalue problem arises in many applications and has received a great deal of attention over the last decade.   the use of root - finding methods to solve the polynomial eigenvalue problem dates back to the work of kublanovskaya ( 1969, 1970 ) and has received a resurgence due to the work of bini and noferini ( 2013 ). in this paper, we present a method which uses laguerre iteration for computing the eigenvalues of a matrix polynomial. an effective method based on the numerical range is presented for computing initial estimates to the eigenvalues of a matrix polynomial.   a detailed explanation of the stopping criteria is given, and it is shown that under suitable conditions we can guarantee the backward stability of the eigenvalues computed by our method. then, robust methods are provided for computing both the right and left eigenvectors and the condition number of each eigenpair.   applications for hessenberg and tridiagonal matrix polynomials are given and we show that both structures benefit from substantial computational savings. finally, we present several numerical experiments to verify the accuracy of our method and its competitiveness for solving the roots of a polynomial and the tridiagonal eigenvalue problem.   matrix polynomial, polynomial eigenvalue problem, root - finding algorithm, laguerre s method    15a22, 15a18, 47j10, 65f15
the process of capture of a molecular enesemble into rotational resonance in the optical centrifuge is investigated.   the adiabaticity and phase space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters @xmath0 characterising the driving strength and the nonlinearity, and related to three characteristic time scales in the problem.   the analysis is based on the transformation to action - angle variables and the single resonance approximation, yielding reduction of the  three - dimensional rotation problem to one degree of freedom.   the analytic results for capture probability are in a good agreement with simulations.   the existing experiments satisfy the validity conditions of the theory.
we study a model of particle acceleration coupled with an mhd model of magnetic reconnection in unstable twisted coronal loops.   the kink instability leads to the formation of helical currents with strong parallel electric fields resulting in electron acceleration.   the motion of electrons in the electric and magnetic fields of the reconnecting loop is investigated using a test - particle approach taking into account collisional scattering.   we discuss the effects of coulomb collisions and magnetic convergence near loop footpoints on the spatial distribution and energy spectra of high - energy electron populations and possible implications on the hard x - ray emission in solar flares.
we investigate critical slowing down in the local updating continuous - time quantum monte carlo method by relating the finite size scaling of fisher zeroes to the dynamically generated gap, through the scaling of their respective critical exponents. as we comment, the nonlinear sigma model representation derived through the hamiltonian of our lattice spin model   can also be used to give a effective treatment of planar anomalous dimensions in @xmath0=4 sym.   we present scaling arguments from our fss analysis to discuss quantum corrections and recent 2-loop results, and further comment on the prospects of extending this approach for calculating higher twist parton distributions.
spin propagation in systems of one - dimensional interacting fermions at finite temperature is intrinsically diffusive  . the spreading rate of a spin packet is controlled by a transport coefficient termed  spin drag " relaxation time @xmath0. in this paper   we present both numerical and analytical calculations of @xmath0 for a two - component spin - polarized cold fermi gas trapped inside a tight atomic waveguide. at low temperatures we find an activation law for @xmath0, in agreement with earlier calculations of coulomb drag between slightly asymmetric quantum wires, but with a different and much stronger temperature dependence of the prefactor.   our results provide a fundamental input for microscopic time - dependent spin - density functional theory calculations of spin transport in @xmath1 inhomogeneous systems of interacting fermions.
we study the mechanism of particle production in the world - volume of a probe @xmath0-brane ( or @xmath1 with susy breaking ) moving in the background created by a fixed stack of @xmath1-branes.   we show that this may occur in a regime of parametric resonance when the probe s motion is non - relativistic and it moves at large distances from the source branes in low eccentricity orbits.   this leads to an exponential growth of the particle number in the probe s world - volume and constitutes an effective mechanism for producing very massive particles.   we also analyze the evolution of this system in an expanding universe and how this affects the development of the parametric resonance.   we discuss the effects of transverse space compactification on the probe s motion, showing that it leads to the creation of angular momentum in a similar way to the affleck - dine mechanism for baryogenesis.   finally, we describe possible final states of the system and their potential relevance to cosmology.
in a previous paper, we have described a method to perform fixed - node quantum monte carlo calculations for lattice fermions. in this paper, we present an extension of this method, by which it is possible to find information on the properties of the exact ground - state wave function.   we give some further illustrations of the fnmc and the extended methods.
we follow the contraction and evolution of a typical jupiter - mass clump created by the disk instability mechanism, and compute the rate of planetesimal capture during this evolution.   we show that such a clump has a slow contraction phase lasting @xmath0 years. by following the trajectories of planetesimals   as they pass through the envelope of the protoplanet, we compute the cross - section for planetesimal capture at all stages of the protoplanet s evolution.   we show that the protoplanet can capture a large fraction of the solid material in its feeding zone, which will lead to an enrichment of the protoplanet in heavy elements.   the exact amount of this enrichment depends upon, but is not very sensitive to the size and random speed of the planetesimals.   * key words * accretion, jupiter, planetary formation
this work presents a general formalism to analyze a generic bulk scalar field in a multiple warped extra - dimensional model with arbitrary number of extra dimensions.   the kaluza - klein mass modes along with the self - interaction couplings are determined and the possibility of having lowest lying kk mode masses near tev scale are discussed.   also some numerical values for low - lying kk modes has been presented showing explicit localization around tev scale.   it is argued that the appearance of large number of closely spaced kk modes with enhanced coupling may prompt possible new signatures in collider physics.
observations of very - high - energy ( vhe, @xmath0  gev ) @xmath1-ray emission from several blazars at @xmath2 have placed stringent constraints on the elusive spectrum and intensity of the intergalactic infrared background radiation ( iibr ). correcting their observed vhe spectrum for @xmath3 absorption even by the lowest plausible level of the iibr   provided evidence for a very hard ( photon spectral index @xmath4 ) intrinsic source spectrum out to tev energies.   such a hard vhe @xmath1-ray spectrum poses a serious challenge to the conventional synchrotron - self - compton interpretation of the vhe emission of tev blazars and suggests the emergence of a separate emission component beyond a few hundred gev.   here we propose that such a very hard, slowly variable vhe emission component in tev blazars may be produced via compton upscattering of cosmic microwave background ( cmb ) photons by shock - accelerated electrons in an extended jet.   for the case of 1es  1101 - 232, this component could dominate the bolometric luminosity of the extended jet if the magnetic fields are of the order of typical intergalactic magnetic fields ( @xmath5 g ) and electrons are still being accelerated out to tev energies ( @xmath6 ) on kiloparsec scales along the jet.
motivated by the importance of non - collinear and non - coplanar magnetic phases in determining various electrical properties of magnetic materials, we investigate the phase diagrams of the extended hubbard model on anisotropic triangular lattice.   we make use of a mean - field scheme that treats collinear, non - collinear and non - coplanar phases on equal footing.   in addition to the ferromagnetic and 120@xmath0antiferromagnetic phases, we find the four - sublattice flux, the 3q non - coplanar and the non - collinear charge - ordered states to be stable at specific values of filling fraction @xmath1.   inter - site coulomb repulsion leads to intriguing spin - charge ordered phases.   most notable of these are the collinear and non - collinear magnetic states at @xmath2, which occur together with a pinball - liquid - like charge order.   our results demonstrate that the elementary single - orbital extended hubbard model on a triangular lattice hosts unconventional spin - charge ordered phases, which have been reported in more complex and material - specific electronic hamiltonians relevant to layered triangular systems.
we have obtained _ chandra _ acis - s observations of ngc  6543, the cat s eye nebula. the x - ray emission from ngc  6543   is clearly resolved into a point source at the central star and diffuse emission confined within the central elliptical shell and two extensions along the major axis.   spectral analysis of the diffuse component shows that the abundances of the x - ray - emitting gas are similar to those of the fast ( 1,750 km  s@xmath0 ) stellar wind but not those of the nebula.   furthermore, the temperature of this gas is @xmath11.7@xmath210@xmath3 k, which is 100 times lower than the expected post - shock temperature of the fast stellar wind.   the combination of low temperature and wind abundances is puzzling.   the thermal pressure of this hot gas is about twice the pressure in the cool nebular shell ; thus, the hot gas plays an essential role in the ongoing evolution of the nebula.
muon lepton flavor processes are reviewed in connection with search for physics beyond the standard model.   several methods to distinguish different theoretical models are discussed for @xmath0, @xmath1, and @xmath2 conversion processes.   new calculation of the @xmath2 conversion rate is presented including a higgs boson mediated effect in the supersymmetric seesaw model.
the authors present a relativistic and cross - section factorized framework for computing quasielastic @xmath0 observables at intermediate and high energies.   the model is based on the eikonal approximation and can accomodate both optical potentials and the glauber method for dealing with the initial- and final - state interactions ( ifsi ). at lower nucleon energies,   the optical - potential philosophy is preferred, whereas at higher energies the glauber method is more natural.   this versatility in dealing with the ifsi allows one to describe @xmath0 reactions in a wide energy range.   most results presented here use optical potentials as this approach is argued to be the optimum choice for the kinematics of the experiments considered in the present paper.   the properties of the ifsi factor, a function wherein the entire effect of the ifsi is contained, are studied in detail.   the predictions of the presented framework are compared with two kinematically different experiments.   first, differential cross sections for quasielastic proton scattering at @xmath1  gev off @xmath2c, @xmath3o, and @xmath4ca target nuclei are computed and compared to data from pnpi.   second, the formalism is applied to the analysis of a @xmath5he@xmath6 experiment at @xmath7  mev.   the optical - potential calculations are found to be in good agreement with the data from both experiments, showing the reliability of the adopted model in a wide energy range.
the inhomogeneous fluctuations that underlie structure formation  galaxies and cmb hot spots  might have been seeded by quantum cosmological fluctuations, as magnified by some inflationary mechanism.   the halliwell  hawking model for these, as a lower - energy semiclassical limit, is expected to be shared by many theories.   e.g. an @xmath0 suppression of power at large scales results from this.   this model contains / suppresses very many terms ; we want a qualitative understanding of the meaning of these terms and of different regimes resulting from different combinations of them.   i study this with toy models that have tractable mathematics : minisuperspace and, especially, relational particle mechanics. in the present seminar,   i consider in particular averaged terms with some lessons from hartree   fock approach to atomic and molecular physics.   one needs to anchor this on variational principles ; treating the subsequent equations is a _ numerical _ venture.    *   edward anderson *   .    invited seminar at xxix - th international workshop on high energy physics : new results and actual problems in particle & astroparticle physics and cosmology ( moscow 2013 ).
we report on the development of a technique for precise radial - velocity measurements of cool stars and brown dwarfs in the near infrared.   our technique is analogous to the iodine ( @xmath0 ) absorption cell method that has proven so successful in the optical regime.   we rely on telluric ch@xmath1 absorption features to serve as a wavelength reference, relative to which we measure doppler shifts of the co and h@xmath2o features in the spectra of our targets.   we apply this technique to high - resolution ( r@xmath350,000 ) spectra near 2.3@xmath4 of nine l dwarfs taken with the phoenix instrument on gemini - south and demonstrate a typical precision of 300 m s@xmath5.   we conduct simulations to estimate our expected precision and show our performance is currently limited by the signal - to - noise of our data.   we present estimates of the rotational velocities and systemic velocities of our targets. with our current data,   we are sensitive to companions with @xmath6 in orbits with periods less than three days.   we identify no companions in our current data set.   future observations with improved signal - to - noise should result in radial - velocity precision of 100 m s@xmath5 for l dwarfs.
in quantum dots or molecules with vibrational degrees of freedom the electron - vibron coupling renormalizes the electronic charging energy. for sufficiently strong coupling,   the renormalized charging energy can become negative. here  , we discuss an instability towards adding or removing an arbitrary number of electrons when the magnitude of the renormalized charging energy exceeds the single - particle level spacing.   we show that the instability is regularized by the anharmonic contribution to the vibron energy.   the resulting effective charging energy as a function of the electron number has a double - well structure causing a variety of novel features in the coulomb blockade properties.
an accurate geometric distortion solution for the _ hubble space telescope _   uvis - channel of wide field camera 3 is the first step towards its use for high precision astrometry. in this work we present an average correction that enables a relative astrometric accuracy of @xmath01 mas ( in each axis for well exposed stars ) in three broad - band ultraviolet filters ( f225w, f275w, and f336w ).   more data and a better understanding of the instrument are required to constrain the solution to a higher level of accuracy.
the amplitude of jet distortions and accompanying pressure and velocity fluctuations resulting from kelvin - helmholtz instability of three dimensional relativistic jets are explored.   the effect of instability on jets as they accelerate from sub- to super - alfvnic speeds is explored and a relativistic stabilization mechanism for trans - alfvnic jets is proposed. the level to which asymmetric instabilities on supermagnetosonic relativistic jets will grow   is predicted theoretically and a doppler boosted `` apparent '' emissivity is computed.   effects due to helically twisted filamentary structure produced by asymmetric modes of instability should be readily observable on relativistic jets.
the interacting binary white dwarf ( am cvn ) systems hm cnc and v407 have orbital periods of 5.4 min and 9.5 min, respectively.   the two systems are characterized by an `` on / off '' behaviour in the x - ray light curve, and optical light curves that are nearly sinusoidal and which lead the x - ray light curves in phase by about 0.2 in both systems. of the models that have been proposed to explain the observations, the one that seems to require the least fine tuning is the _ direct impact _ model of marsh & steeghs ( 2002 ). in this model,   the white dwarf primary is large enough relative to the semi - major axis that the accretion stream impacts the surface of the primary white dwarf directly without forming an accretion disc.   marsh & steeghs ( 2002 ) proposed that in this situation there could be a flow set up around the equator with a decreasing surface temperature the further one measured from the impact point. in this study, we estimate the light curves that might result from such a temperature distribution, and find them to be reasonable approximations to the observations.   one unexpected result is that two distinct x - ray spots must exist to match the shape of the x - ray light curves.       accretion, accretion discs  binaries : general, close  hydrodynamics  novae, cataclysmic variables  stars : individual(hm cnc ; v407 vul )  white dwarfs  x - rays : binaries  x - rays : stars.
in this work we study an ultrastrong coupled qubit - cavity system subjected to slow repeated measurements. we demonstrate that even under a few imperfect measurements it is possible to detect transitions of the qubit from its free ground state to the excited state.   the excitation probability grows exponentially fast in analogy with the quantum anti - zeno effect.   the dynamics and physics described in this paper is accessible to current superconducting circuit technology.
leptons do not interact strongly with the hot dense medium created in relativistic heavy ion collisions.   they can escape the interaction region undistorted and thus carry direct information about the space - time evolution of the expanding system. in the low mass region ( lmr, @xmath0 gev/@xmath1 ), dielectron mass spectra can provide the in - medium vector meson properties, while in the intermediate mass region ( imr, @xmath2 gev/@xmath1 ), the slope of dielectron transverse mass spectra is expected to have connection with the qgp temperature.    in this paper, we present the centrality and @xmath3 dependence of the dielectron mass spectra measured in star experiment at rhic.   the data sets used in the analysis include large statistics samples collected during years 2010 for 200 gev au+au collisions and 2012 for 200 gev p+p collisions. in order to extract underlying physics  , we will compare our results with model calculations.
neutral hydrogen vla d - array observations of the dwarf irregular galaxy hoii, a prototype galaxy for studies of shell formation and self - propagating star formation, are presented.   the large - scale h@xmath0i  morphology is reminiscent of ram pressure and is unlikely caused by interactions. a case   is made for intragroup gas in poor and compact groups similar to the m81 group, to which hoii belongs.   numerous shortcomings of the supernova explosions and stellar winds scenario to create the shells in hoii are highlighted, and it is suggested that ram pressure may be able to reconcile the numerous observations available.   ps.   @plainmkbothoddheadoddfoot``dwarf galaxies and their environment '' ; international conference in bad honnef, germany, 23 - 27 january 2001evenheadevenfootoddfoot
recent _ _ beppo__sax observations of arp  299, a powerful far - ir merging starburst system composed of ic  694 and ngc  3690, clearly unveiled for the first time in this system the presence of a strongly absorbed active galactic nucleus ( agn ).   however the system was not spatially resolved by _ _ beppo__sax. here   we present the analysis of archival _ chandra _ and ( for the first time ) xmm-_newton _ observations, which allow us to disentangle the x - ray emission of the two galaxies.   the detection of a strong @xmath0kev line in ngc  3690 clearly demonstrates the existence of an agn in this galaxy, while the presence of a strong @xmath1kev fe - k@xmath2 line in the spectrum of ic  694 suggests that also this nucleus might harbor an agn.   this would be the second discovery of two agns in a merging system after ngc  6240.
the recent measurement of the differential @xmath0-jet cross section, performed at the tevatron collider in run ii by the d0 collaboration, is studied in a next - to - leading order ( nlo ) global qcd analysis to assess its impact on the proton parton distribution functions ( pdfs ).   we show that these data lead to a significant change on the gluon and charm quark distributions.   we demonstrate also that there is an inconsistency between the new high precision hera i+ii combined data and tevatron measurement.   moreover, in this study we investigate the impact of older emc measurements of charm structure function @xmath1 on the pdfs and compare the results with those gaining from the analysis of tevatron data.   we show that both of them have a same impact on pdfs, and thus can be recognized as same evidences for inefficiency of perturbative qcd in dealing with the charm production in some kinematic regions.
we study the dynamics of the magellanic clouds in a model for the local group whose mass is constrained using the timing argument / two - body limit of the action principle.   the goal is to evaluate the role of m31 in generating the high angular momentum orbit of the clouds, a puzzle that has only been exacerbated by the latest @xmath0 proper motion measurements.   we study the effects of varying the total local group mass, the relative mass of the milky way and m31, the proper motion of m31, and the proper motion of the lmc on this problem. over a large part of this parameter - space we find that tides from m31 are insignificant. for a range of lmc proper motions   approximately @xmath1 higher than the mean and total local group mass @xmath2, m31 can provide a significant torque to the lmc orbit.   however, if the lmc is bound to the mw, then m31 is found to have negligible effect on its motion and the origin of the high angular momentum of the system remains a puzzle.   finally, we use the timing argument to calculate the total mass of the mw - lmc system based on the assumption that they are encountering each other for the first time, their previous perigalacticon being a hubble time ago, obtaining @xmath3.
+ related to an idea of lewin, a mathematical model for behavioral changes under the influence of a social field is developed.   the social field reflects public opinion, social norms and trends.   it is not only given by external factors ( the environment ) but also by the interactions of individuals.   two important kinds of interaction processes are distinguished : imitative and avoidance processes.   variations of individual behavior are taken into account by `` diffusion coefficients ''.   + key words : behavioral model, field theory, diffusion model, decision theory, pair interactions, imitative and avoidance processes    @twoside -32pt    a mathematical model for the behavior of + individuals in a social field    * a mathematical model for the behavior of + individuals in a social field *
in molecular devices electronic degrees of freedom are coupled to vibrational modes of the molecule, offering an opportunity to study fundamental aspects of this coupling at the nanoscale. to this end   we consider the nonequilibrium heat exchange between a conduction band and a bosonic bath mediated by a single molecule. for molecules large enough so that on - site coulomb repulsion can be dropped  , we carry out an asymptotically exact calculation of the heat current, governed by the smallness of the electron - phonon coupling, and obtain the steady state heat current driven by a finite temperature drop. at low temperatures   the heat current is found to have a power - law behavior with respect to the temperature difference with the power depending on the nature of the bosonic bath. at high temperatures, on the other hand,   the current is linear in the temperature difference for all types of bosonic baths.   the crossover between these behaviors is described.   some of the results are given a physical explanation by comparing to a perturbative master equation calculation ( whose limitation we examine ).
we compare the non - linear matter power spectrum in real space calculated analytically from 3rd - order perturbation theory with @xmath0-body simulations at @xmath1.   we find that the perturbation theory prediction agrees with the simulations to better than 1% accuracy in the weakly non - linear regime where the dimensionless power spectrum, @xmath2, which approximately gives variance of matter density field at a given @xmath3, is less than 0.4.   while the baryonic acoustic oscillation features are preserved in the weakly non - linear regime at @xmath4, the shape of oscillations is distorted from the linear theory prediction.   nevertheless, our results suggest that one can correct the distortion caused by non - linearity _ almost exactly_. we also find that perturbation theory, which does not contain any free parameters, provides a significantly better fit to the simulations than the conventional approaches based on empirical fitting functions to simulations.   the future work would include perturbation theory calculations of non - linearity in redshift space distortion and halo biasing in the weakly non - linear regime.
we examine the cosmic star formation rate ( sfr ) and its dependence on galaxy stellar mass over the redshift range @xmath0 using data from the gemini deep deep survey ( gdds ).   the sfr in the most massive galaxies ( @xmath1 ) was six times higher at @xmath2 than it is today.   it drops steeply from @xmath2, reaching the present day value at @xmath3.   in contrast, the sfr density of intermediate mass galaxies ( @xmath4 ) declines more slowly and may peak or plateau at @xmath5.   we use the characteristic growth time @xmath6 to provide evidence of an associated transition in massive galaxies from a burst to a quiescent star formation mode at @xmath7.   intermediate mass systems transit from burst to quiescent mode at @xmath8, while the lowest mass objects undergo bursts throughout our redshift range.   our results show unambiguously that the formation era for galaxies was extended and proceeded from high to low mass systems.   the most massive galaxies formed most of their stars in the first @xmath9 gyr of cosmic history.   intermediate mass objects continued to form their dominant stellar mass for an additional @xmath10 gyr, while the lowest mass systems have been forming over the whole cosmic epoch spanned by the gdds.   this view of galaxy formation clearly supports ` downsizing'in the sfr where the most massive galaxies form first and galaxy formation proceeds from larger to smaller mass scales.
we calculate the strong radiative corrections to the process @xmath0. at the tevatron this process is the largest background to the associated higgs boson production @xmath1.   the calculation is based on the subtraction procedure, and the corrections are found to be significant.   # 1#2#3 _ phys.   lett.  _ * # 1 *, # 2 ( 19#3 ) # 1#2#3 _ zeit.   phys.  _ * # 1 *, # 2 ( 19#3 ) # 1#2#3 _ phys.   rev.  _   * # 1 *, # 2 ( 19#3 ) # 1#2#3 _ nucl.  phys.  _ * # 1 *, # 2 ( 19#3 ) # 1#2#3 _ ibid.  _ * # 1 *, # 2 ( 19#3 ) # 1#2#3 _ comp.   phys.   comm.  _   * # 1 *, # 2 ( 19#3 )    1.5 cm     + 0.7 cm r.k.   ellis and sinia veseli + 0.1 cm theory group, fermi national accelerator laboratory, p.o.   box 500, batavia, il 60510 + 0.1 cm    0.7 cm
the influence of the isospin - independent, isospin- and momentum - dependent equation of state ( eos ), as well as the coulomb interaction on the pion production in intermediate energy heavy ion collisions ( hics ) is studied for both isospin - symmetric and neutron - rich systems.   the coulomb interaction plays an important role in the reaction dynamics, and strongly influences the rapidity and transverse momentum distributions of charged pions.   it even leads to the @xmath0 ratio deviating slightly from unity for isospin-_symmetric _ systems.   the coulomb interaction between mesons and baryons is also crucial for reproducing the proper pion flow since it changes the behavior of the directed and the elliptic flow components of pions visibly.   the eos can be better investigated in neutron - rich system if _   multiple _ probes are measured simultaneously.   for example, the rapidity and the transverse momentum distributions of the charged pions, the @xmath0 ratio, the various pion flow components, as well as the _ difference _ of @xmath1-@xmath2 flows. a new sensitive observable   is proposed to probe the symmetry potential energy at high densities, namely the transverse momentum distribution of the elliptic flow difference [ @xmath3.
the capture and gradual inspiral of stellar mass objects by a massive black hole at the centre of a galaxy has been proposed as one of the most promising source of gravitational radiation to be detected by lisa.   unfortunately rate estimates for this process suffer from many uncertainties. here   we report on the use of our newly developed monte carlo stellar dynamics code to tackle this problem.   we present results from simple galactic nuclei models that demonstrate the high potential of our approach and point out the aspects of the problem where an improved treatment seems desirable.
we study the melting of a @xmath0 condensate in hot and neutrino - trapped protoneutron stars. in this connection, we adopt relativistic field theoretical models to describe the hadronic and condensed phases.   it is observed that the critical temperature of antikaon condensation is enhanced as baryon density increases. for a fixed baryon density,   the critical temperature of antikaon condensation in a protoneutron star is smaller than that of a neutron star.   we also exhibit the phase diagram of a protoneutron star with a @xmath0 condensate.
a remarkable number of different numerical algorithms can be understood and analyzed using the concepts of symmetric spaces and lie triple systems, which are well known in differential geometry from the study of spaces of constant curvature and their tangents.   this theory can be used to unify a range of different topics, such as polar - type matrix decompositions, splitting methods for computation of the matrix exponential, composition of selfadjoint numerical integrators and dynamical systems with symmetries and reversing symmetries.   the thread of this paper is the following : involutive automorphisms on groups induce a factorization at a group level, and a splitting at the algebra level. in this paper   we will give an introduction to the mathematical theory behind these constructions, and review recent results.   furthermore, we present a new yoshida - like technique, for self - adjoint numerical schemes, that allows to increase the order of preservation of symmetries by two units. since all the time - steps are positive, the technique is particularly suited to stiff problems, where a negative time - step can cause instabilities.
employing the lattice gas model, combined with the linear elasticity theory, a correlation between the equilibrium and transport properties of intercalated species is investigated.   it is shown that the major features of the intercalation isotherms and the concentration dependence of the chemical diffusion coefficient can be well understood in terms of the change of the host volume in the course of intercalation.   theoretical predictions are compared to the experimental observations on @xmath0, @xmath1 and @xmath2-graphite systems.   + _ pacs numbers : _ 68.35.ct, 68.35.rh    2
we have applied a variational algorithm based on projected entangled pair states ( peps ) to a two dimensional frustrated spin system, the spin-1/2 antiferromagnetic heisenberg model on the shastry - sutherland lattice.   we use the class of peps with internal tensor dimension @xmath0, the first step beyond product states ( @xmath1 peps ).   we have found that the @xmath0 variational peps algorithm is able to capture the physics in both the valence - bond crystal and the neel ordered state.   also the spin - textures giving rise to the magnetization plateaus seen in experiments on srcu@xmath2(bo@xmath3)@xmath2 are well reproduced.   this shows that peps with the smallest nontrivial internal dimension, @xmath0, can provide valuable insights into frustrated spin - systems.
we introduce a convergent iterative algorithm for finding the optimal coding and decoding operations for an arbitrary noisy quantum channel.   this algorithm does not require any error syndrome to be corrected completely, and hence also finds codes outside the usual knill - laflamme definition of error correcting codes.   the iteration is shown to improve the figure of merit `` channel fidelity '' in every step.
the formalism of quantum theory in hilbert space has been applied with success to the modeling and explanation of several cognitive phenomena, whereas traditional cognitive approaches were problematical. however  , this ` quantum cognition paradigm'was recently challenged by its proven impossibility to simultaneously model ` question order effects'and ` response replicability '. in part   i of this paper we describe sequential dichotomic measurements within an operational and realistic framework for human cognition elaborated by ourselves, and represent them in a quantum - like ` extended bloch representation'where the born rule of quantum probability does not necessarily hold.   in part ii we apply this mathematical framework to successfully model question order effects, response replicability and unpacking effects, thus opening the way toward quantum cognition beyond hilbert space @xcite.    :   human cognition, cognitive modeling, quantum structures, general tension - reduction model
we discuss a new analytical approach to real - time evolution in quantum many - body systems.   our approach extends the framework of continuous unitary transformations such that it amounts to a novel solution method for the heisenberg equations of motion for an operator.   it is our purpose to illustrate the accuracy of this approach by studying dissipative quantum systems on all time scales.   in particular, we obtain results for non - equilibrium correlation functions for general initial conditions.   we illustrate our ideas for the exactly solvable dissipative oscillator, and, as a non - trivial model, for the dissipative two - state system.
a numerical characterization is given of the so - called @xmath0-triangles of sequentially cohen - macaulay simplicial complexes.   this result characterizes the number of faces of various dimensions and codimensions in such a complex, generalizing the classical macaulay - stanley theorem to the nonpure case.   moreover, we characterize the possible betti tables of componentwise linear ideals.   a key tool in our investigation is a bijection between shifted multicomplexes of degree @xmath1 and shifted pure @xmath2-dimensional simplicial complexes.
we find that imposing the crossing symmetry in the iteration process considerably extends the range of convergence for solutions of the parquet equations for the hubbard model.   when the crossing symmetry is not imposed, the convergence of both simple iteration and more complicated continuous loading ( homotopy ) methods are limited to high temperatures and weak interactions.   we modify the algorithm to impose the crossing symmetry without increasing the computational complexity.   we also imposed time reversal and a subset of the point group symmetries, but they did not further improve the convergence.   we elaborate the details of the latency hiding scheme which can significantly improve the performance in the computational implementation. with these modifications,   stable solutions for the parquet equations can be obtained by iteration more quickly even for values of the interaction that are a significant fraction of the bandwidth and for temperatures that are much smaller than the bandwidth.   this may represent a crucial step towards the solution of two - particle field theories for correlated electron models.
ant colony optimization ( aco ) has time complexity @xmath0, and its typical application is to solve traveling salesman problem ( tsp ), where @xmath1, @xmath2, and @xmath3 denotes the iteration number, number of ants, number of cities respectively.   cutting down running time is one of study focuses, and one way is to decrease parameter @xmath1 and @xmath3, especially @xmath3. for this focus,   the following method is presented in this paper.   firstly, design a novel clustering algorithm named special local clustering algorithm ( slc ), then apply it to classify all cities into compact classes, where compact class is the class that all cities in this class cluster tightly in a small region.   secondly, let aco act on every class to get a local tsp route.   thirdly, all local tsp routes are jointed to form solution.   fourthly, the inaccuracy of solution caused by clustering is eliminated.   simulation shows that the presented method improves the running speed of aco by 200 factors at least. and this high speed is benefit from two factors.   one is that class has small size and parameter @xmath3 is cut down.   the route length at every iteration step is convergent when aco acts on compact class.   the other factor is that, using the convergence of route length as termination criterion of aco and parameter @xmath1 is cut down
a three - dimensional monte carlo code for modelling radiation transport in type ia supernovae is described.   in addition to tracking monte carlo quanta to follow the emission, scattering and deposition of radiative energy, a scheme involving volume - based monte carlo estimators is used to allow properties of the emergent radiation field to be extracted for specific viewing angles in a multi - dimensional structure.   this eliminates the need to compute spectra or light curves by angular binning of emergent quanta.   the code is applied to two test problems to illustrate consequences of multi - dimensional structure on the modelling of light curves.   first, elliptical models are used to quantify how large scale asphericity can introduce angular dependence to light curves.   secondly, a model which incorporates complex structural inhomogeneity, as predicted by modern explosion models, is used to investigate how such structure may affect light curve properties.       radiative transfer  methods : numerical  supernovae : general
we propose a novel mechanism for the protection against spin gapped states in doped antiferromagnets.   it requires the presence of a chern - simons term that can be generated by a coupling between spin and an insulator.   we first demonstrate that in the presence of this term the vortex loop excitations of the spin sector behave as anyons with fractional statistics.   to generate such term, the fermions should have massive dirac spectrum coupled to the emergent spin field of the spin sector.   the dirac spectrum can be realized by a planar spin configuration arising as the lowest - energy configuration of a square lattice antiferromagnet hamiltonian involving a dzyaloshinskii - moriya interaction.   the mass is provided by a combination of dimerization and staggered chemical potential.   we finally show that for realistic parameters, anyonic vortex loop condensation will likely never occur and thus the spin gapped state is prevented.   we also propose real magnetic materials for an experimental verification of our theory.
chubukov s proposal concerning the possibility of a nondimerized quantum nematic phase in the ground - state phase diagram of the bilinear - biquadratic spin-1 chain is studied numerically.   our results do not support the existence of this phase, but they rather indicate a direct transition from the ferromagnetic into the dimerized phase.
far - infrared maps obtained with isophot have been searched for point - like sources.   the majority of the 55 sources is believed to be extragalactic and in most cases no previously known sources can be associated with them.   based on the far - infrared spectral energy distributions it is likely that dust - enshrouded, distant galaxies form a significant fraction of the sources.   we estimate the number densities of extragalactic sources at 90@xmath0 m, 150@xmath0 m and 180@xmath0 m wavelengths and at flux density levels down to @xmath1100mjy.   the counts are compared with models of galaxy evolution.   the counts exceed the predictions of current models, even those with strong evolution, and no - evolution models are rejected at a high confidence level.   comparison with recent results from cobe mission indicates that at 90@xmath0 m the detected sources correspond to @xmath220% of the extragalactic background light. at longer wavelengths the corresponding fraction is 10%.        
possible manifestation of the family non   universal @xmath0 boson effects in lepton polarization in rare, exclusive baryonic @xmath1 decay is examined.   it is observed that the double lepton polarizations @xmath2 and @xmath3 are sensitive to the @xmath0 contribution.   moreover, it is found that the zero position of the polarized forward   backward asymmetry @xmath4 is shifted to the left compared to the standard model prediction.   therefore, determination of the zero value of @xmath4 is quite an efficient tool for establishing new @xmath0 boson, but also in discriminating various scenarios of the considered family non   universal @xmath0 model.    0^*0   5_5 s_s^??   o _ ^0 _    pacs numbers : 13.30.a, 14.20.mr
we present the first investigation of the extrapolation of quenched nucleon magnetic moments in quenched chiral effective field theory.   we utilize established techniques in finite - range regularisation and compare with standard dimensional regularisation methods.   finite - volume corrections to the relevant loop integrals are also addressed.   finally, the contributions of dynamical sea quarks to the proton moment are estimated using a recently discovered phenomenological link between quenched and physical qcd.
we experimentally examine a laser - induced underwater shock wave with a special attention to pressure impulse, the time integral of pressure evolution. plasma formation, shock - wave expansion, and pressure in water   are observed simultaneously using a combined measurement system that obtains high - resolution nanosecond - order image sequences.   these detailed measurements reveal a non - spherically - symmetric distribution of pressure peak, which is inconsistent with a well - known spherical - shock model. in contrast, remarkably, pressure impulse is found to distribute symmetrically for a wide range of experimental parameters.   the structure is determined to be a collection of multiple spherical shocks originated from elongated plasmas.
interface states at a boundary between regions with different spin - orbit interactions ( sois ) in two - dimensional ( 2d ) electron systems are investigated within the one - band effective mass method with generalized boundary conditions for envelope functions.   we have found that the interface states unexpectedly exist even if the effective interface potential equals zero.   depending on the system parameters, the energy of these states can lie in either or both forbidden and conduction bands of bulk states.   the interface states have chiral spin texture similar to that of the edge states in 2d topological insulators.   however, their energy spectrum is more sensitive to the interfacial potential, the largest effect being produced by the spin - dependent component of the interfacial potential.   we have also studied the size quantization of the interface states in a strip of 2d electron gas with soi and found an unusual ( non - monotonic ) dependence of the quantization energy on the strip width.
the dispersion relation of surface waves of a magnetic fluid in a magnetic field is studied experimentally.   we verify the theoretically predicted existence of a non - monotonic dispersion relation.   in particular, we demonstrate the existence of two different wave numbers occuring at the same frequency in an annular geometry.
in this paper we propose an extension of the model of liu, coppersmith et al.   @xcite, in order to allow for arch formation.   this extended model qualitatively captures interesting properties of granular materials due to fluctuations of stress paths, such as stress fluctuations and stick - slip motion.
weak magnetism increases antineutrino mean free paths in core collapse supernovae.   the parity violating interference between axial and vector currents makes antineutrino - nucleon cross sections smaller then those for neutrinos.   we calculate simple, exact correction factors to include recoil and weak magnetism in supernova simulations.   weak magnetism may significantly increase the neutrino energy flux.   we calculate, in a diffusion approximation, an increase of order 15% in the total energy flux for temperatures near 10 mev.   this should raise the neutrino luminosity.   weak magnetism also changes the emitted spectrum of @xmath0 ( with @xmath1 or @xmath2 ) and @xmath3.   we estimate that @xmath4 will be emitted about 7% hotter than @xmath5 because @xmath4 have longer mean free paths.   likewise weak magnetism may increase the @xmath3 temperature by of order 10%.   this increase in temperature coupled with the increase in neutrino luminosity should increase the heating in the low density region outside of the neutrino sphere.   this, in turn, could be important for the success of an explosion.   it is important to check our results with a full simulation that includes boltzmann neutrino transport and weak magnetism corrections.
we apply the truncated wigner method to the process of three - body recombination in ultracold bose gases.   we find that within the validity regime of the wigner truncation for two - body scattering, three - body recombination can be treated using a set of coupled stochastic differential equations that include diffusion terms, and can be simulated using known numerical methods. as an example we investigate the behaviour of a simple homogeneous bose gas.
monte carlo simulations of the transport of protons in human tissue have been deployed on graphics processing units ( gpus ) with impressive results. to provide a more complete treatment of non - elastic nuclear interactions in these simulations  , we developed a fast intranuclear cascade - evaporation simulation for the gpu.   this can be used to model non - elastic proton collisions on any therapeutically relevant nuclei at incident energies between 20 and 250 mev.   predictions are in good agreement with geant4.9.6p2.   it takes approximately 2 s to calculate @xmath0 200 mev proton-@xmath1o interactions on a nvidia gtx680 gpu. a speed - up factor of @xmath220 relative to one intel i7 - 3820 core processor thread   was achieved.   = 1    monte carlo, proton transport, nuclear cascade, evaporation, gpu, cuda
we have performed an in - depth concept study of a gravitational wave data analysis method which targets repeated long quasi - monochromatic transients ( triggers ) from cosmic sources.   the algorithm concept can be applied to multi - trigger data sets in which the detector - source orientation and the statistical properties of the data stream change with time, and does not require the assumption that the data is gaussian. reconstructing or limiting the energetics of potential gravitational wave emissions associated with quasi - periodic oscillations ( qpos ) observed in the x - ray lightcurve tails of soft gamma repeater flares might be an interesting endeavour of the future.   therefore we chose this in a simplified form to illustrate the flow, capabilities, and performance of the method.   we investigate performance aspects of a multi - trigger based data analysis approach by using @xmath0 long stretches of mock data in coincidence with the times of observed qpos, and by using the known sky location of the source.   we analytically derive the pdf of the background distribution and compare to the results obtained by applying the concept to simulated gaussian noise, as well as off - source playground data collected by the 4-km hanford detector ( h1 ) during ligo s fifth science run ( s5 ).   we show that the transient glitch rejection and adaptive differential energy comparison methods we apply succeed in rejecting outliers in the s5 background data.   finally, we discuss how to extend the method to a network containing multiple detectors, and as an example, tune the method to maximize sensitivity to sgr 1806@xmath120 flare times.
we present an improved calibration of photometric metallicity indicators, derived from the new metallicity scale for globular clusters presented by carretta & gratton ( 1997 ) and based on direct high resolution spectroscopy of 160 stars in 24 globular clusters.   we have carefully recalibrated the traditional abundance indices based upon the red giant branch ( rgb ) morphology, both in the @xmath0 and @xmath1 planes, namely the dereddened colour at the luminosity level of the horizontal branch ( hb ), and the magnitude difference between the hb and the rbg at a given dereddened colour.   finally, we give new accurate relations to employ in the simultaneous metallicity reddening method by sarajedini ( 1994 ), also tied to the carretta & gratton ( 1997 ) abundance scale.
the evolution of the magnetic moment and various features of the electronic structure of fcc gd are followed to reduced volume @xmath0 using the lda+u correlated band method.   the stability of the moment is substantial ; crude estimates of this signature of a possible `` mott transition '' in the @xmath1 system suggest a critical pressure @xmath2 500 gpa. the @xmath1 occupation is found to _ increase _ under pressure due to broadening and lowering of the minority states. this trend is consistent with the interpretation of x - ray spectra of maddox _ et al. _ across the volume collapse transition at 59 gpa, and tends to support their suggestion that the delocalization of the @xmath1 states in gd differs from the original abrupt picture, being instead a process that occurs over an extended range of pressure.
this paper presents a method for automated healing as part of off - line automated troubleshooting.   the method combines statistical learning with constraint optimization.   the automated healing aims at locally optimizing radio resource management ( rrm ) or system parameters of cells with poor performance in an iterative manner.   the statistical learning processes the data using logistic regression ( lr ) to extract closed form ( functional ) relations between key performance indicators ( kpis ) and radio resource management ( rrm ) parameters.   these functional relations are then processed by an optimization engine which proposes new parameter values.   the advantage of the proposed formulation is the small number of iterations required by the automated healing method to converge, making it suitable for off - line implementation.   the proposed method is applied to heal an inter - cell interference coordination ( icic ) process in a 3 g long term evolution ( lte ) network which is based on soft - frequency reuse scheme.   numerical simulations illustrate the benefits of the proposed approach.   * keywords : * statistical learning, logistic regression, automated healing, troubleshooting, inter - cellular interference coordination, lte.
we propose a quantum processor for the scalable quantum computation on microwave photons in distant one - dimensional superconducting resonators.   it is composed of a common resonator @xmath0 acting as a quantum bus and some distant resonators @xmath1 coupled to the bus in different positions assisted by superconducting quantum interferometer devices ( squid ), different from previous processors.   @xmath0 is coupled to one transmon qutrit, and the coupling strengths between @xmath1 and @xmath0 can be fully tuned by the external flux through the squid. to show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high - fidelity quantum state transfer between two distant microwave - photon resonators and another one for the high - fidelity controlled - phase gate on them. by using the technique for catching and releasing the microwave photons from resonators, our processor may play an important role in quantum communication as well.
using scattering theory, we investigate interferometers composed of chiral majorana fermion modes coupled to normal metal leads.   we advance an approach in which also the basis states in the normal leads are written in terms of majorana modes.   thus each pair of electron - hole states is associated with a pair of majorana modes.   only one lead majorana mode couples to the intrinsic majorana mode whereas its partner is completely reflected. similarly the remaining majorana modes are completely reflected but in general mix pair - wise.   we demonstrate that the charge current can also be expressed in terms of interference between pairs of majorana modes.   these two basic facts permit a treatment and understanding of current and noise signatures of chiral majorana fermion interferometry in an especially elegant way. as a particular example of applications, in fabry - perot - type interferometers where chiral majorana modes form loops  , resonances ( anti - resonances ) from such loops always lead to peaked ( suppressed ) andreev differential conductances, and negative ( positive ) cross - correlations that originate purely from two - majorana - fermion exchange.   these investigations are intimately related to current and noise signatures of majorana bound states.
the einstein radius of a cluster provides a relatively model - independent measure of the mass density of a cluster within a projected radius of @xmath0 kpc, large enough to be relatively unaffected by gas physics.   we show that the observed einstein radii of four well - studied massive clusters, for which reliable virial masses are measured, lie well beyond the predicted distribution of einstein radii in the standard @xmath1cdm model. based on large samples of numerically simulated cluster - sized objects with virial masses   @xmath2, the predicted einstein radii are only @xmath3, a factor of two below the observed einstein radii of these four clusters.   this is because the predicted mass profile is too shallow to exceed the critical surface density for lensing at a sizable projected radius.   after carefully accounting for measurement errors as well as the biases inherent in the selection of clusters and the projection of mass measured by lensing, we find that the theoretical predictions are excluded at a 4-@xmath4 significance.   since most of the free parameters of the @xmath1cdm model now rest on firm empirical ground, this discrepancy may point to an additional mechanism that promotes the collapse of clusters at an earlier time thereby enhancing their central mass density.       galaxies : clusters : general  cosmology : theory  galaxies : formation  cosmological parameters  dark matter
we investigate the plasma dynamics ( outflow speed and turbulence ) inside polar plumes.   we compare line profiles ( mainly of ) observed by the uvcs instrument on soho at the minimum of solar cycle 22 - 23 with model calculations.   we consider maxwellian velocity distributions with different widths in plume and inter - plume regions.   electron densities are assumed to be enhanced in plumes and to approach inter - plume values with increasing height.   different combinations of the outflow and turbulence velocity in the plume regions are considered.   we compute line profiles and total intensities of the  ly@xmath0 and the doublets.   the observed profile shapes and intensities are reproduced best by a small solar wind speed at low altitudes in plumes that increases with height to reach ambient inter - plume values above roughly 3 - 4 @xmath1 combined with a similar variation of the width of the velocity distribution of the scattering atoms / ions.   we also find that plumes very close to the pole give narrow profiles at heights above 2.5  @xmath1, which are not observed.   this suggests a tendency for plumes to be located away from the pole.   we find that the inclusion of plumes in the model computations provides an improved correspondence with the observations and confirms previous results showing that published uvcs observations in polar coronal holes can be roughly reproduced without the need for large temperature anisotropy.   the latitude distributions of plumes and magnetic flux distributions are studied by analyzing data from different instruments on soho and with solis.
we classify legendrian rational unknots with tight complements in the lens spaces @xmath0 up to coarse equivalence. as an example of the general case,   this classification is also worked out for @xmath1.   the knots are described explicitly in a contact surgery diagram of the corresponding lens space.
recent analysis of relativistically expanding shells of cosmological @xmath0-ray bursts standard and not peak luminosity ( @xmath1 ). assuming a flat friedmann cosmology ( @xmath2, @xmath3 ) and constant rate density ( @xmath4 ) of bursting sources, we fit a standard candle energy to a uniformly selected log  @xmath5-log  @xmath6 in the batse 3b catalog correcting for fluence efficiency and averaging over   48 observed spectral shapes.   we find the data consistent with @xmath7 ergs and discuss implications of this energy for cosmological models of @xmath0-ray bursts.
we study the effective hamiltonian for strong - coupling lattice qcd in the case of non - zero baryon density. in leading order   the effective hamiltonian is a generalized antiferromagnet. for naive fermions,   the symmetry is @xmath0 and the spins belong to a representation that depends on the local baryon number.   next - nearest neighbor ( ) terms in the hamiltonian break the symmetry to @xmath1.   we transform the quantum problem to a euclidean sigma model which we analyze in a @xmath2 expansion. in the vacuum sector   we recover spontaneous breaking of chiral symmetry for the nearest - neighbor and  theories. for non - zero baryon density we study the nearest - neighbor theory only, and   show that the pattern of spontaneous symmetry breaking depends on the baryon density.
to solve hard problems, ai relies on a variety of disciplines such as logic, probabilistic reasoning, machine learning and mathematical programming.   although it is widely accepted that solving real - world problems requires an integration amongst these, contemporary representation methodologies offer little support for this.    in an attempt to alleviate this situation  , we introduce a new declarative programming framework that provides abstractions of well - known problems such as sat, bayesian inference, generative models, and convex optimization.   the semantics of programs is defined in terms of first - order structures with semiring labels, which allows us to freely combine and integrate problems from different ai disciplines.
we present an analysis of the credit market of japan.   the analysis is performed by investigating the bipartite network of banks and firms which is obtained by setting a link between a bank and a firm when a credit relationship is present in a given time window. in our investigation   we focus on a community detection algorithm which is identifying communities composed by both banks and firms.   we show that the clusters obtained by directly working on the bipartite network carry information about the networked nature of the japanese credit market.   our analysis is performed for each calendar year during the time period from 1980 to 2011.   specifically, we obtain communities of banks and networks for each of the 32 investigated years, and we introduce a method to track the time evolution of these communities on a statistical basis.   we then characterize communities by detecting the simultaneous over - expression of attributes of firms and banks.   specifically, we consider as attributes the economic sector and the geographical location of firms and the type of banks. in our 32 year long analysis   we detect a persistence of the over - expression of attributes of clusters of banks and firms together with a slow dynamics of changes from some specific attributes to new ones.   our empirical observations show that the credit market in japan is a networked market where the type of banks, geographical location of firms and banks and economic sector of the firm play a role in shaping the credit relationships between banks and firms.
digital synoptic sky surveys pose several new object classification challenges. in surveys where real - time detection and classification of transient events is a science driver,   there is a need for an effective elimination of instrument - related artifacts which can masquerade as transient sources in the detection pipeline, e.g., unremoved large cosmic rays, saturation trails, reflections, crosstalk artifacts, etc.   we have implemented such an artifact filter, using a supervised neural network, for the real - time processing pipeline in the palomar - quest ( pq ) survey.   after the training phase, for each object it takes as input a set of measured morphological parameters and returns the probability of it being a real object. despite the relatively low number of training cases for many kinds of artifacts, the overall artifact classification rate is around 90%, with no genuine transients misclassified during our real - time scans.   another question is how to assign an optimal star - galaxy classification in a multi - pass survey, where seeing and other conditions change between different epochs, potentially producing inconsistent classifications for the same object.   we have implemented a star / galaxy multipass classifier that makes use of external and a priori knowledge to find the optimal classification from the individually derived ones. both these techniques can be applied to other, similar surveys and data sets.   address = california institute of technology, mc 105 - 24, 1200 e. california bl.  , pasadena, ca 91109, usa    ,
in this paper the benefits provided by multi - cell processing of signals transmitted by mobile terminals which are received via dedicated relay terminals ( rts ) are assessed.   unlike previous works, each rt is assumed here to be capable of full - duplex operation and receives the transmission of adjacent relay terminals.   focusing on intra - cell tdma and non - fading channels, a simplified uplink cellular model introduced by wyner is considered.   this framework facilitates analytical derivation of the per - cell sum - rate of multi - cell and conventional single - cell receivers.   in particular, the analysis is based on the observation that the signal received at the base stations can be interpreted as the outcome of a two - dimensional linear time invariant system.   numerical results are provided as well in order to provide further insight into the performance benefits of multi - cell processing with relaying.
we present a calculation of the spectrum of light and heavy quark bound states in the rainbow - ladder truncation of dyson - schwinger / bethe - salpeter equations. by extending   the formalism include the case of total angular momentum @xmath0, we are able to explore regge trajectories and make prediction of tensor bound states for light and heavy quarkonia.
we show that, independently of the scalar field potential and of specific asymptotic properties of the spacetime ( asymptotically flat, de sitter or anti - de sitter ), any static, spherically symmetric or planar, black hole or soliton solution of the einstein theory minimally coupled to a real scalar field with a general potential is mode stable under linear odd - parity perturbations. to this end  , we generalize the regge - wheeler equation for a generic self - interacting scalar field, and show that the potential of the relevant schrdinger operator can be mapped, by the so - called s - deformation, to a semi - positively defined potential. with these results at hand   we study the existence of slowly rotating configurations.   the frame dragging effect is compared with the kerr black hole.
we study a sudden interaction quench in the weak - coupling regime of the quantum sine - gordon model.   the real time dynamics of the bosonic mode occupation numbers is calculated using the flow equation method.   while we can not prove results for the asymptotic long time limit, we can establish the existence of an extended regime in time where the mode occupation numbers relax to twice their equilibrium values.   this factor two indicates a non - equilibrium distribution and is a universal feature of weak interaction quenches.   the weak - coupling quantum sine - gordon model therefore turns out to be on the borderline between thermalization and non - thermalization.
using the adaptive optics system, hokupaa, at gemini - north, we have directly imaged a companion around the ukirt faint standard m8 star, lhs 2397a ( fs 129 ) at a separation of 2.96 au.   near - infrared photometry of the companion has shown it to be an l7.5 brown dwarf and confirmed the spectral type of the primary to be m8.   we also derive a substellar mass of the companion of @xmath0, although masses in the range @xmath1 are possible, and the primary mass as @xmath2.   reanalysis of archival imaging from hst has confirmed the secondary as a common proper motion object.   this binary represents the first clear example of a brown dwarf companion within 4 au of a low mass star and should be one of the first late l dwarfs to have a dynamical mass. as part of a larger survey of m8-l0 stars, this object may indicate that there is no `` brown dwarf desert '' around low mass primaries.
we present analysis of c7.0 solar flare of febrary 17, 2013, revealing a strong helioseismic response ( sunquake ) caused by a very compact impact in the photosphere.   this is the weakest known c - class flare generating a sunquake event. to investigate possible mechanisms of this event, and to understand the role of   accelerated charged particles and photospheric electric currents, we use data from three space observatories : ramaty high energy solar spectroscopic imager ( rhessi ), solar dynamics observatory ( sdo ) and geostationary operational environmental satellite ( goes ).   we find that the photospheric flare impact does not spatially correspond to the strongest hxr emission source, but both of these events are parts of the same energy release.   our analysis reveals a close association of the flare energy release with a rapid increase of the electric currents, and suggests that the sunquake initiation is unlikely to be explained by the impact of high - energy electrons but may be associated with a rapid current dissipation or a localized impulsive lorentz force.
to obtain the initial pressure from the collected data on a planar sensor arrangement in photoacoustic tomography, there exists an exact analytic frequency domain reconstruction formula.   an efficient realization of this formula needs to cope with the evaluation of the data s fourier transform on a non - equispaced mesh. in this paper  , we use the non - uniform fast fourier transform to handle this issue and show its feasibility in 3d experiments.   this is done in comparison to the standard approach that uses polynomial interpolation.   moreover, we investigate the effect and the utility of flexible sensor location on the quality of photoacoustic image reconstruction.   the computational realization is accomplished by the use of a multi - dimensional non - uniform fast fourier algorithm, where non - uniform data sampling is performed both in frequency and spatial domain.   we show that with appropriate sampling the imaging quality can be significantly improved.   reconstructions with synthetic and real data show the superiority of this method.   * keywords : * image reconstruction, photoacoustics, non - uniform fft
spontaneously created vortex - antivortex pairs are the predominant source of flux noise in high - temperature superconductors. in principle,   flux noise measurements allow to check theoretical predictions for both the distribution of vortex - pair sizes and for the vortex diffusivity. in this paper   the flux - noise power spectrum is calculated for the highly anisotropic high - temperature superconductor bi@xmath0sr@xmath0cacu@xmath0o@xmath1, both for bulk crystals and for ultra - thin films.   the spectrum is basically given by the fourier transform of the temporal magnetic - field correlation function.   we start from a berezinskii - kosterlitz - thouless type theory and incorporate vortex diffusion, intra - pair vortex interaction, and annihilation of pairs by means of a fokker - planck equation to determine the noise spectrum below and above the superconducting transition temperature.   we find white noise at low frequencies @xmath2 and a spectrum proportional to @xmath3 at high frequencies.   the cross - over frequency between these regimes strongly depends on temperature.   the results are compared with earlier results of computer simulations.
the _ marenostrum universe _ is one of the largest cosmological sph simulation done so far.   it consists of @xmath0 dark and @xmath0 gas particles in a box of 500 @xmath1 mpc on a side.   here we study the shapes and spins of the dark matter and gas components of the 10,000 most massive objects extracted from the simulation as well as the gas fraction in those objects.   we find that the shapes of objects tend to be prolate both in the dark matter and gas.   there is a clear dependence of shape on halo mass, the more massive ones being less spherical than the less massive objects.   the gas distribution is nevertheless much more spherical than the dark matter, although the triaxiality parameters of gas and dark matter differ only by a few percent and it increases with cluster mass.   the spin parameters of gas and dark matter can be well fitted by a lognormal distribution function. on average,   the spin of gas is 1.4 larger than the spin of dark matter.   we find a similar behavior for the spins at higher redshifts, with a slightly decrease of the spin ratios to 1.16 at @xmath2 the cosmic normalized baryon fraction in the entire cluster sample ranges from @xmath3, at @xmath4 to @xmath5 at @xmath6. at both redshifts   we find a slightly, but statistically significant decrease of @xmath7 with cluster mass.
we investigate possible extensions of the ( 2 + 1 ) dimensional @xmath0 model to the noncommutative space. up to the leading nontrivial order of @xmath1  , we prove that the model restricted to the left fundamental representation of the gauge group is renormalizable and does not have dangerous infrared divergences.   in contrast, if the basic field @xmath2 transforms in accord with the adjoint representation, infrared singularities are present in the two point function of the auxiliary gauge field and also in the leading correction to the self - energy of the @xmath2 field  . these infrared divergences may produce nonintegrable singularities leading at higher orders to a breakdown of the @xmath1 expansion.   gauge invariance of the renormalization procedure is also discussed.
we present results of rxte observations of the low - mass x - ray binary and atoll source 4u1608@xmath052 made over 9 days during the decline of an x - ray intensity outburst in march 1996.   a fast - timing analysis shows a strong and narrow quasi periodic oscillation ( qpo ) peak at frequencies between 850 and 890 hz on march 3 and 6, and a broad peak around 690 hz on march 9.   observations on march 12 show no significant signal. on march 3,   the x - ray spectrum of the qpo is quite hard ; its strength increases steadily from 5 % at @xmath12 to @xmath120 % at @xmath112  kev.   the qpo frequency varies between 850 and 890 hz on that day, and the peak widens and its rms decreases with centroid frequency in a way very similar to the well - known horizontal branch oscillations ( hbo ) in z - sources.   we apply the hbo beat frequency model to atoll sources, and suggest that, whereas the model could produce qpos at the observed frequencies, the lack of correlation we observe between qpo properties and x - ray count rate is hard to reconcile with this model.
recently, song et al  employed transition - voltage spectroscopy to demonstrate that the energy @xmath0 of the highest occupied molecular orbital ( homo ) of single - molecule transistors can be controlled by a gate potential @xmath1. to demonstrate the linear dependence @xmath2, the experimental data have been interpreted by modeling the molecule as an energy barrier spanning the spatial source - drain region of molecular junctions.   since, as shown in this work, that crude model can not quantitatively describe the measured @xmath3-@xmath4-characteristics, it is important to get further support for the linear dependence of @xmath0 on @xmath1.   the results presented here, which have been obtained within a model of a point - like molecule, confirm this linear dependence. because the two models rely upon complementary descriptions,   the present results indicate that the interpretation of the experimental results as evidence for a gate controlled homo is sufficiently general.   @xmath5 +
for a large class of quantum systems the statistical properties of their spectrum show remarkable agreement with random matrix predictions.   recent advances show that the scope of random matrix theory is much wider. in this work, we show that the random matrix approach can be beneficially applied to a completely different classical domain, namely, to the empirical correlation matrices obtained from the analysis of the basic atmospheric parameters that characterise the state of atmosphere.   we show that the spectrum of atmospheric correlation matrices satisfy the random matrix prescription.   in particular, the eigenmodes of the atmospheric empirical correlation matrices that have physical significance are marked by deviations from the eigenvector distribution.    2
this paper presents a novel framework for track fitting which is usable in a wide range of experiments, independent of the specific event topology, detector setup, or magnetic field arrangement.   this goal is achieved through a completely modular design.   fitting algorithms are implemented as interchangeable modules. at present  , the framework contains a validated kalman filter.   track parameterizations and the routines required to extrapolate the track parameters and their covariance matrices through the experiment are also implemented as interchangeable modules.   different track parameterizations and extrapolation routines can be used simultaneously for fitting of the same physical track.   representations of detector hits are the third modular ingredient to the framework.   the hit dimensionality and orientation of planar tracking detectors are not restricted.   tracking information from detectors which do not measure the passage of particles in a fixed physical detector plane, e.g.  drift chambers or tpcs, is used without any simplifications.   the concept is implemented in a light - weight c++ library called genfit, which is available as free software.   track fitting, track reconstruction, kalman filter, drift chamber, tpc
we consider pricing weather derivatives for use as protection against weather extremes.   the method described utilizes results from spatial statistics and extreme value theory to first model extremes in the weather as a max - stable process, and then use these models to simulate payments for a general collection of weather derivatives.   these simulations capture the spatial dependence of payments. incorporating results from catastrophe ratemaking  , we show how this method can be used to compute risk loads and premiums for weather derivatives which are renewal - additive.   +    extreme value, generalized extreme value distribution, max - stable process, renewal - additive, weather derivative
in this lecture i give a brief review of low - dimensional few - body problems recently encountered in attempting a quantitative description of ultracold atoms and molecules confined in 2d and 1d optical lattices.   multi - channel nature of these processes has required the development of special computational methods and algorithms which i discuss here as well as the most interesting results obtained with the offered computational technique and future perspectives.   trap, ultracold atoms, feshbach resonance, confinement - induced resonance, few - body problem, schrdinger equation, scattering problem, discrete variable representation, boundary - value problem, splitting - up method
we examine the corrections to the lowest order gravitational interactions of massive particles arising from gravitational radiative corrections.   we show how the masslessness of the graviton and the gravitational self interactions imply the presence of nonanalytic pieces @xmath0, etc. in the form factors of the energy - momentum tensor and   that these correspond to long range modifications of the metric tensor @xmath1 of the form @xmath2, etc.   the former coincide with well known solutions from classical general relativity, while the latter represent new quantum mechanical effects, whose strength and form is necessitated by the low energy quantum nature of the general relativity.   we use these results to define a running gravitational charge.
we consider the minimal two - band model for the fe - based superconductors with a phenomenological pairing interaction which mimics short - range antiferromagnetic ( afm ) fluctuations.   two superconducting ( sc ) gap solutions are found to exist with the model : sign - changing s - wave gap ( @xmath0s - wave ) and double d - wave gap states.   both solutions hold the approximate relation @xmath1, a generic feature of two band model with a dominant interband pairing interaction.   we carried out the calculations of the sc properties of the both sc states such as the density of states, temperature dependencies of spin - lattice relaxation rate @xmath2, knight shift, and penetration depth, particularly taking into account of the interband coherence factors.   the results are discussed in comparison with the currently available experimental data.
we review our version of the classical field approximation to the dynamics of a finite temperature bose gas. in the case of a periodic box potential  , we investigate the role of the high momentum cut - off, essential in the method.   in particular, we show that the cut - off going to infinity limit decribes the particle number going to infinity with the scattering length going to zero. in this weak interaction limit  , the relative population of the condensate tends to unity.   we also show that the cross - over energy, at which the probability distribution of the condensate occupation changes its character, grows with a growing scattering length. in the more physical case of the condensate in the harmonic trap we investigate the dissipative dynamics of a vortex.   we compare the decay time and the velocities of the vortex with the available analytic estimates.
no - scale supersymmetry or gaugino mediation augmented with large negative higgs soft masses at the input scale provides a simple solution to the supersymmetric flavor problem while giving rise to a neutralino lsp.   however, to obtain a neutralino lsp it is often necessary to have tachyonic input higgs soft masses that can give rise to charge - and - color - breaking ( ccb ) minima and unbounded - from - below ( ufb ) directions in the low energy theory.   we investigate the vacuum structure in these theories to determine when such problematic features are present. when the standard electroweak vacuum is only metastable, we compute its lifetime under vacuum tunneling.   we find that vacuum metastability leads to severe restrictions on the parameter space for larger @xmath0, while for smaller @xmath1, only minor restrictions are found. along the way  , we derive an exact bounce solution for tunneling through an inverted parabolic potential.   cern - ph - th/2008 - 249 + mctp-08 - 67 +    vacuum stability with tachyonic boundary + higgs masses in no - scale supersymmetry + or gaugino mediation    jason  l.  evans@xmath2, david  e.  morrissey@xmath3, james  d.  wells@xmath2 +    @xmath4  michigan center for theoretical physics ( mctp ) + university of michigan, ann arbor, mi 48109 + @xmath5  cern, theory division, ch-1211 geneva 23, switzerland + @xmath6  jefferson laboratory of physics, harvard university + cambridge, massachusetts 02138
the finite element computation of structures such as waveguides can lead to heavy computations when the length of the structure is large compared to the wavelength.   such waveguides can in fact be seen as one - dimensional periodic structures. in this paper   a simple recursive method is presented to compute the global dynamic stiffness matrix of finite periodic structures.   this allows to get frequency response functions with a small amount of computations.   examples are presented to show that the computing time is of order @xmath0 where @xmath1 is the number of periods of the waveguide.   number of pages : 23    number of figures : 11    number of tables : 1    periodic structure, waveguide, finite element, recursive, dynamic, vibration
we present early time, high resolution spectroscopy of three grb afterglows : grb050730, 050922c and 060418.   these data give us precious information on the kinematics, ionization and metallicity of the interstellar matter of grb host galaxies up to a redshift z @xmath0, and of intervening absorbers along the line of sight.   
we have measured the thermopower across the metamagnetic transition of the heavy fermion compound ceru@xmath0si@xmath0 at temperatures down to 0.1k and magnetic fields up to 11.5 t.   we find a large negative enhancement of the thermopower on crossing the metamagnetic field, as well as a sudden change in slope.   we argue that this is consistent with the zeeman - driven deformation of the fermi surface through a topological transition.   the field dependence of the thermopower highlights the discrepancy between thermodynamic and transport properties across the metamagnetic transition.
some recent investigations of spectropolarimetric observations of the zeeman effect in the fe i lines at 630 nm carried out with the _ hinode _ solar space telescope have concluded that the strength of the magnetic field vector in the internetwork regions of the quiet sun is in the hg regime and that its inclination is predominantly horizontal.   we critically reconsider the analysis of such observations and carry out a complete bayesian analysis with the aim of extracting as much information as possible from them, including error bars.   we apply the recently developed bayes - me  code that carries out a complete bayesian inference for milne - eddington atmospheres.   the sampling of the posterior distribution function is obtained with a markov chain monte carlo scheme and the marginal distributions are analyzed in detail.   the kullback - leibler divergence is used to study the extent to which the observations introduce new information in the inference process resulting in sufficiently constrained parameters.   our analysis clearly shows that only upper limits to the magnetic field strength can be inferred with fields in the kg regime completely discarded.   furthermore, the noise level present in the analyzed _ hinode _ observations induces a substantial loss of information for constraining the azimuth of the magnetic field.   concerning the inclination of the field, we demonstrate that some information is available to constrain it for those pixels with the largest polarimetric signal  . the results also point out that the field in pixels with small polarimetric signals can be nicely reproduced in terms of a quasi - isotropic distribution.
we investigate the dynamics of a quantum system coupled linearly to gaussian white noise using functional methods. by performing the integration over the noisy field in the evolution operator,   we get an equivalent non - hermitian hamiltonian, which evolves the quantum state with a dissipative dynamics.   we also show that if the integration over the noisy field is done for the time evolution of the density matrix, a gain contribution from the fluctuations, can be accessed in addition to the loss one from the non - hermitian hamiltonian dynamics.   we illustrate our study by computing analytically the effective non - hermitian hamiltonian, which we found to be the complex frequency harmonic oscillator, with a known evolution operator.   it leads to space and time localisation, a common feature of noisy quantum systems in general applications.
relativistic jets in agn in general, and in blazars in particular, are the most energetic and among the most powerful astrophysical objects known so far.   their relativistic nature provides them with the ability to emit profusely at all spectral ranges from radio wavelengths to @xmath0-rays, as well as to vary extremely at time scales from hours to years. since the birth of @xmath0-ray astronomy, locating the origin of @xmath0-ray emission has been a fundamental problem for the knowledge of the emission processes involved.   deep and densely time sampled monitoring programs with the _ fermi _ gamma - ray space telescope and other facilities at most of the available spectral ranges ( including millimeter interferometric imaging and polarization measurements wherever possible ) are starting to shed light for the case of blazars.   after a short review of the status of the problem, we summarize two of our latest results obtained from the comprehensive monitoring data compiled by the boston university blazar monitoring program  that locate the gev flaring emission of the bl lac objects ao  0235 + 164 and oj287 within the jets of these blazars, at @xmath1 parsecs from the central agn engine.
the dynamics of bose - einstein condensation in a three - dimensional harmonic trap is studied explicitly including the bogoliubov approximation for temperatures below the critical one. to model the evolution towards equilibrium at each cooling step,   we derive quantum kinetic equations that describe the dynamics of the gas for temperatures above and below the transition temperature.   these equations, valid in the born and markov approximations, consider the essential role of the chemical potential as the main parameter that signals the transition. the kinetic equation that describes the growth of the condensate below the transition temperature is derived within the bogoliubov approximation. to illustrate our results we propose an energetic cooling protocol and simulate the whole sequence of the formation of a condensate.
bianchi type v string cosmological models with bulk viscosity for massive string are investigated.   the bulk viscosity is assumed to vary with time in such a manner that it is related to simple power function of the energy density. using generation technique ( camci  et  al., 2001 ), it is shown that einstein s field equations are solvable for any arbitrary cosmic scale function.   solution for particular form of cosmic scale functions are also obtained.   it is found that solutions based on generation technique are relevant to the observational results.   some physical and geometrical aspect of the models are also discussed.   +     +   +   +   +    pacs : 98.80.cq, 98.80.-k + key words : bianchi type v universe, string theory, bulk viscosity.
angular momentum in protostellar discs can be transported either radially, through turbulence induced by the magnetorotational instability ( mri ), or vertically, through the torque exerted by a large - scale magnetic field.   we present a model of steady - state discs where these two mechanisms operate at the same radius and derive approximate criteria for their occurrence in an ambipolar diffusion dominated disc.   we obtain `` weak field '' solutions  which we associate with the mri channel modes in a stratified disc  and transform them into accretion solutions with predominantly radial angular - momentum transport by implementing a turbulent - stress prescription based on published results of numerical simulations.   we also analyze `` intermediate field strength '' solutions in which both radial and vertical transport operate at the same radial location.   our results suggest, however, that this overlap is unlikely to occur in real discs.
using a collective coordinate numerical optimization procedure, we construct ground - state configurations of interacting particle systems in various space dimensions so that the scattering of radiation exactly matches a prescribed pattern for a set of wave vectors.   we show that the constructed ground states are, counterintuitively, disordered ( i.e., possess no long - range order ) in the infinite - volume limit.   we focus on three classes of configurations with unique radiation scattering characteristics : ( i)``stealth '' materials, which are transparent to incident radiation at certain wavelengths ; ( ii)``super - ideal '' gases, which scatter radiation identically to that of an ensemble of ideal gas configurations for a selected set of wave vectors ; and ( iii)``equi - luminous '' materials, which scatter radiation equally intensely for a selected set of wave vectors.   we find that ground - state configurations have an increased tendency to contain clusters of particles as one increases the prescribed luminosity.   limitations and consequences of this procedure are detailed.
there has been a lively debate in many fields, including statistics and related applied fields such as psychology and biomedical research, on possible reforms of the scholarly publishing system.   currently, referees contribute so much to improve scientific papers, both directly through constructive criticism and indirectly through the threat of rejection.   we discuss ways in which new approaches to journal publication could continue to make use of the valuable efforts of peer reviewers.   nicolas chopin + _ ensae, and crest, paris _ + nicolas.chopin@ensae.dauphine.fr + andrew gelman + _ department of statistics and department of political science, columbia university _ + gelman@stat.columbia.edu + kerrie l. mengersen + _ mathematical sciences, queensland university of technology _ + k.mengersen@qut.edu.au + christian p.  robert + _ universit   paris - dauphine, ceremade, iuf, and crest, paris _   + xian@ceremade.dauphine.fr   * keywords : * peer review, refereeing, scientific publishing
we study the causal structure of the minimal surface of the four - gluon scattering, and find a world - sheet wormhole parametrized by mandelstam variables, thereby demonstrate the epr = er relation for gluon scattering.   we also propose that scattering amplitude is the change of the entanglement entropy by generalizing the holographic entanglement entropy of ryu - takayanagi to the case where two regions are divided in space - time.
the geometric phases of a two - level atom interacting with non - markovian environments are calculated and the non - markovian effects on the geometric phases are discussed in this paper.   three kinds of methods that describe the non - markovian process, projection superoperator technique, memory kernel master equation and post - markovian master equation, are used in the discussions.   the results show that when the dissipation rate is large, the non - markovian effects change the geometric phase more strikingly than the small one.
we use a simple machine learning model, logistically - weighted regularized linear least squares regression, in order to predict baseball, basketball, football, and hockey games.   we do so using only the thirty - year record of which visiting teams played which home teams, on what date, and what the final score was.   no real `` statistics '' are used.   the method works best in basketball, likely because it is high - scoring and has long seasons.   it works better in football and hockey than in baseball, but in baseball the predictions are closer to a theoretical optimum.   the football predictions, while good, can in principle be made much better, and the hockey predictions can be made somewhat better.   these findings tells us that in basketball, most statistics are subsumed by the scores of the games, whereas in football, further study of game and player statistics is necessary to predict games as well as can be done.   baseball and hockey lie somewhere in between.
we investigate the evolution of metal deficient stellar structures, presenting h - burning isochrones covering cluster ages from 800 myr to 7 gyr.   evolutionary evidences for selection effects in the metallicity distribution of very metal poor h - burning red giants are reported.   the evolution of stars during central and shell he burning is further investigated, discussing the occurrence of he burning pulsators as a function of cluster age.
the process of heat conduction in one - dimensional lattice with on - site potential is studied by means of numerical simulation. using discrete frenkel - kontorova, @xmath04 and sinh - gordon   we demonstrate that contrary to previously expressed opinions the sole anharmonicity of the on - site potential is insufficient to ensure the normal heat conductivity in these systems.   the character of the heat conduction is determined by the spectrum of nonlinear excitations peculiar for every given model and therefore depends on the concrete potential shape and temperature of the lattice.   the reason is that the peculiarities of the nonlinear excitations and their interactions prescribe the energy scattering mechanism in each model. for models   sin - gordon and @xmath04 phonons are scattered at thermalized lattice of topological solitons ; for sinh - gordon and @xmath04 - models the phonons are scattered at localized high - frequency breathers ( in the case of @xmath04 the scattering mechanism switches with the growth of the temperature ).
we investigate the continuum @xmath0-potts model at its transition point from the disordered to the ordered regime, with particular emphasis on the coexistence of disordered and ordered phases in the high-@xmath0 case.   we argue that occurrence of phase transition can be seen as percolation in the related random cluster representation, similarly to the lattice potts model, and investigate the typical structure of clusters for high @xmath0.   we also report on numerical simulations in two dimensions using a continuum version of the swendsen - wang algorithm, compare the results with earlier simulations which used the invaded cluster algorithm, and discuss implications on the geometry of clusters in the disordered and ordered phases.   keywords : continuum potts model, first - order phase transition, continuum percolation, continuum swendsen - wang cluster algorithm
high energy scattering was recently shown to be similar to a reaction - diffusion process.   the latter defines a wide universality class that also contains e.g. some specific population evolution models.   the common point of all these models is that their respective dynamics are described by noisy traveling wave equations.   this observation has led to a new understanding of qcd in the regime of high energies, and known universal results on reaction - diffusion models could be transposed to obtain quantitative properties of qcd amplitudes.   conversely, new general results for that kind of statistical models have also been derived.   furthermore, an intriguing relationship between noisy traveling wave equations and the theory of spin glasses was found.
it is argued that the use of the initial gaussian energy density profile for hydrodynamics leads to much better uniform description of the rhic heavy - ion data than the use of the standard initial condition obtained from the glauber model. with the modified gaussian initial conditions we successfully reproduce the @xmath0-spectra, @xmath1, and the pionic hbt radii ( including their azimuthal dependence ). the emerging consistent picture of hadron production hints that a solution of the long standing rhic hbt puzzle has been found.
we present measurements with a gem based tpc prototypes and the timepix cmos asic as charge collecting anode.   tests with a small prototype were performed in a 5gev electron beam at desy.   it is shown that the point resolution for short drift distances is better than 20@xmath0.   the achieved time resolution is better than 10ns at 100mhz clock frequency.   furthermore, experimental studies with an enlarged pixel size are addressed. to study the performance for longer drift distances a chamber with 26 cm drift length   is operated in bonn. using also gem and timepix for the readout,   data with cosmic muons and a sr@xmath1 source are recorded.   this chamber uses also gems and timepix for the readout.   data with cosmic muons and a sr90 source are recorded.   the dependency of spatial resolution and cluster properties on the drift distance are studied.
antiferromagnetism of ultracold fermions in an optical lattice can be detected by bragg diffraction of light, in analogy to the diffraction of neutrons from solid state materials.   a finite sublattice magnetization will lead to a bragg peak from the @xmath0 crystal plane with an intensity depending on details of the atomic states, the frequency and polarization of the probe beam, the direction and magnitude of the sublattice magnetization, and the finite optical density of the sample.   accounting for these effects we make quantitative predictions about the scattering intensity and find that with experimentally feasible parameters the signal can be readily measured with a ccd camera or a photodiode and used to detect antiferromagnetic order.
we investigate the influence of non equilibrium thermodynamics on cosmological structure formation. in this paper  , we consider the collapse of planar perturbations usually called `` zeldovich pancakes ''.   we have developed for that purpose a new two fluids ( gas and dark matter ) hydrodynamical code, with three different thermodynamical species : electrons, ions and neutral particles @xmath0 ).   we describe in details the complex structure of accretion shock waves.   we include several relevant processes for a low density, high temperature, collisional plasma such as non - equilibrium chemical reactions, cooling, shock heating, thermal energy equipartition between electrons, ions and neutral particles and electronic conduction.   we find two different regions in the pancake structure : a thermal precursor ahead of the compression front and an equipartition wave after the compression front where electrons and ions temperatures differ significantly.   this complex structure may have two interesting consequences : pre - heating of unshocked regions in the vicinity of massive x - ray clusters and ions and electrons temperatures differences in the outer regions of x - rays clusters.   # 1
we present the results of the northern extension of the hi parkes zone of avoidance survey, a blind hi survey utilizing the multibeam receiver on the parkes 64-m telescope. in the two regions studied here, @xmath0 to @xmath1 and @xmath2 to @xmath3, @xmath4,   we have detected 77 hi galaxies, twenty of which have been previously detected in hi.   the survey has a median rms noise of 6.0  mjy  beam@xmath5 and is complete to a mean flux density of 22  mjy.   we have searched for multiwavelength counterparts to the 77 galaxies detected here : 19, 27, and 11 have a likely optical, 2mass, and iras cataloged counterpart, respectively.   a further 16 galaxies have likely visible counterparts on the digitized sky survey.   the detection of these 77 galaxies allows a closer inspection of the large - scale structures in these regions.   we see several filaments crossing the galactic plane, one of which appears to be the continuation of a sine - wave like feature that can be traced across the whole southern sky.   an analysis of the hi mass function suggests that the regions studied here may be underdense.   one particularly noteworthy galaxy is hizoa j0630 + 08 ( @xmath6 = 203@xmath7, 0.9@xmath7 ) with a velocity of @xmath8  km  s@xmath5.   we suggest that it belongs to the nearby orion group which includes a small number of dwarf galaxies.   the newly detected galaxies improve our understanding of the properties of several voids, such as the orion, gemini, and canis major voids.
the ccd magnitudes in johnson @xmath0 and cousins @xmath1 photometric passbands are determined for the optical transient of grb 990123.   these observations have been taken approximately 12 hours after trigger of the gamma - ray burst.   bvr photometric light curves are obtained by combining the published data with the present measurements.   they indicate that the flux decay constants in @xmath0 and @xmath1 passbands are almost the same.   its value is @xmath2.   such decay is quite consistent with the fireball models for the optical transient.   psbox    * optical follow up of the grb 990123 source from upso, nainital *     + _   u. p. state observatory, manora peak, naini tal - 263 129, india _   +   + _ raman research institute, bangalore 560080, india _   + and +   + _ iaa - csic, p.o.   box 03004, e-18080, granada, spain _   +
numerical results from a study of boson stars under nonspherical perturbations using a fully general relativistic 3d code are presented together with the analysis of emitted gravitational radiation.   we have constructed a simulation code suitable for the study of scalar fields in space - times of general symmetry by bringing together components for addressing the initial value problem, the full evolution system and the detection and analysis of gravitational waves. within a series of numerical simulations,   we explicitly extract the zerilli and newman - penrose scalar @xmath0 gravitational waveforms when the stars are subjected to different types of perturbations.   boson star systems have rapidly decaying nonradial quasinormal modes and thus the complete gravitational waveform could be extracted for all configurations studied.   the gravitational waves emitted from stable, critical, and unstable boson star configurations are analyzed and the numerically observed quasinormal mode frequencies are compared with known linear perturbation results.   the superposition of the high frequency nonspherical modes on the lower frequency spherical modes was observed in the metric oscillations when perturbations with radial and nonradial components were applied.   the collapse of unstable boson stars to black holes was simulated.   the apparent horizons were observed to be slightly nonspherical when initially detected and became spherical as the system evolved.   the application of nonradial perturbations proportional to spherical harmonics is observed not to affect the collapse time.   an unstable star subjected to a large perturbation was observed to migrate to a stable configuration.
we revealed the detailed structure of a vastly extended h@xmath0-emitting nebula ( `` h@xmath0 nebula '' ) surrounding the starburst / merging galaxy ngc  6240 by deep narrow - band imaging observations with the subaru suprime - cam.   the extent of the nebula is @xmath190 kpc in diameter and the total h@xmath0 luminosity amounts to @xmath2 erg  s@xmath3.   the volume filling factor and the mass of the warm ionized gas are @xmath110@xmath410@xmath5 and @xmath1@xmath6 @xmath7, respectively.   the nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots.   we found that there is a tight spatial correlation between the h@xmath0 nebula and the extended soft x - ray - emitting gas, both in large and small scales.   the overall morphology of the nebula is dominated by filamentary structures radially extending from the center of the galaxy.   a large - scale bi - polar bubble extends along the minor axis of the main stellar disk.   the morphology strongly suggests that the nebula was formed by intense outflows  superwinds  driven by starbursts.   we also found three bright knots embedded in a looped filament of ionized gas that show head - tail morphologies in both emission - line and continuum, suggesting close interactions between the outflows and star forming regions. based on the morphology and surface brightness distribution of the h@xmath0 nebula  , we propose the scenario that three major episodes of starburst / superwind activities which were initiated @xmath110@xmath8 myr ago formed the extended ionized gas nebula of ngc  6240.
the atmospheric muon and neutrino flux have been simulated using the same approach which successfully accounted for the recent secondary proton, electron and positron flux measurements in orbit by the ams experiment. for the muon flux,   a good agreement is obtained with the caprice and heat data for altitudes ranging from sea level up to about 38  km.   the general features of the calculated atmospheric neutrino flux are reported and discussed. the flux obtained at the super - kamiokande experiment location   are reported and compared with other calculations. for low neutrino energies   the flux obtained is significantly smaller than that used in the data analysis of underground experiment.   the simulation results for the soudan experiment site are also reported.
propagation of dressed solitary excitations are studied in a partially degenerate quantum plasma in the framework of quantum - hydrodynamics ( qhd ) model using multiple scales technique.   the evolution equation together with a linear inhomogeneous differential equation is solved using kodama - taniuti renormalizing technique.   it is shown that the type of solitary excitations ( bright or dark ) is defined by two critical plasma parameter values.   +   + keywords : dressed solitary excitations, partially degenerate plasmas, quantum plasma, quantum hydrodynamics, higher - order nonlinearity +   + pacs : 52.30.ex, 52.35.-g, 52.35.fp, 52.35.mw
in the original holographic dark energy ( hde ) model, the dark energy density is proposed to be @xmath0, with @xmath1 is a dimensionless constant characterizing the properties of the hde. in this work,   we propose the generalized holographic dark energy ( ghde ) model by considering the parameter @xmath1 as a redshift - dependent function @xmath2.   we derive all the physical quantities of the ghde model analytically, and fit the @xmath2 by trying four kinds of parametrizations.   the cosmological constraints of the @xmath2 are obtained from the joint analysis of the present snls3+bao+cmb+@xmath3 data.   we find that, compared with the original hde model, the ghde models can provide a better fit to the data.   for example, the ghde model with jbp - type @xmath2 can reduce the @xmath4 of the hde model by 2.16.   we also find that, unlike the original hde model with a phantom - like behavior in the future, the ghde models can present many more different possibilities, i.e., it allows the ghde in the future to be either quintessence like, cosmological constant like, or phantom like, depending on the forms of @xmath2.
coreas is a monte carlo code for the simulation of radio emission from extensive air showers.   it implements the endpoint formalism for the calculation of electromagnetic radiation directly in corsika. as such  , it is parameter - free, makes no assumptions on the emission mechanism for the radio signals, and takes into account the complete complexity of the electron and positron distributions as simulated by corsika. in this article  , we illustrate the capabilities of coreas with simulations carried out in different frequency ranges from tens of mhz up to ghz frequencies, and describe in particular the emission characteristics at high frequencies due to cherenkov effects arising from the varying refractive index of the atmosphere.
optimized, necessary and sufficient conditions for the identification of the schmidt number will be derived in terms of general hermitian operators.   these conditions apply to arbitrary mixed quantum states.   the optimization procedure delivers equations similar to the eigenvalue problem of an operator.   the properties of the solution of these equations will be studied.   we solve these equations for classes of operators.   the solutions will be applied to phase randomized two - mode squeezed - vacuum states in continuous variable systems.
the rate maximization for the @xmath0-user interference channels ( ics ) has been investigated extensively in the literature. however, the dual problem of minimizing the error probability with given signal modulations and/or data rates of the users is less exploited. in this paper, by utilizing the additional degrees of freedom attained from the _ improper signaling _ ( versus the conventional proper signaling ), we optimize the precoding matrices for the @xmath0-user single - input single - output ( siso ) ics to achieve minimal pair - wise error probability ( pep ) and symbol error rate ( ser ) with two proposed algorithms, respectively.   compared to conventional proper signaling as well as other state - of - the - art improper signaling designs, our proposed improper signaling schemes achieve notable ser improvement in siso - ics under both additive white gaussian noise ( awgn ) channel and cellular system setups.   our study provides another viewpoint for optimizing transmissions in ics and further justifies the practical benefit of improper signaling in interference - limited communication systems  .                interference channels, improper signaling, precoder design, symbol error rate, pair - wise error probability.
this paper develops a contention - based opportunistic feedback technique towards relay selection in a dense wireless network.   this technique enables the forwarding of additional parity information from the selected relay to the destination. for a given network,   the effects of varying key parameters such as the feedback probability are presented and discussed.   a primary advantage of the proposed technique is that relay selection can be performed in a distributed way.   simulation results find its performance to closely match that of centralized schemes that utilize gps information, unlike the proposed method.   the proposed relay selection method is also found to achieve throughput gains over a point - to - point transmission strategy.   automatic repeat request, relays, convolutional codes.
the main inference from the experiments of the 80s that the time - averaged energy spectra of pulsars had to steepen in the gev - tev energy region has been reinforced in the 90s from experiments with higher sensitivities.   however, results from several experiments from the past and the more sensitive experiments at present can be reconciled by invoking a possibly different component arising in the tev region.   the results of the preliminary analysis of the data being collected with the pact array will be presented.
accurate mass determination of clusters of galaxies is crucial if they are to be used as cosmological probes.   however, there are some discrepancies between cluster masses determined based on gravitational lensing, and x - ray observations assuming strict hydrostatic equilibrium(i.e., the equilibrium gas pressure is provided entirely by thermal pressure ).   cosmological simulations suggest that turbulent gas motions remaining from hierarchical structure formation may provide a significant contribution to the equilibrium pressure in clusters.   we analyze a sample of massive clusters of galaxies drawn from high resolution cosmological simulations, and find a significant contribution ( 20%45% ) from non - thermal pressure near the center of relaxed clusters, and, in accord with previous studies, a minimum contribution at about 0.1 @xmath0, growing to about 30%45% at the virial radius, @xmath0.   our results strongly suggest that relaxed clusters should have significant non - thermal support in their core region. as an example, we test the validity of strict hydrostatic equilibrium  in the well - studied massive galaxy cluster abell 1689 using the latest high resolution gravitational lensing and x - ray observations.   we find a contribution of about 40% from non - thermal pressure within the core region of a1689, suggesting an alternate explanation for the mass discrepancy : the strict hydrostatic equilibrium  is not valid in this region.
this paper studies network information theory problems where the external noise is gaussian distributed.   in particular, the gaussian broadcast channel with coherent fading and the gaussian interference channel are investigated.   it is shown that in these problems, non - gaussian code ensembles can achieve higher rates than the gaussian ones.   it is also shown that the strong shamai - laroia conjecture on the gaussian isi channel does not hold. in order to analyze non - gaussian code ensembles over gaussian networks,   a geometrical tool using the hermite polynomials is proposed.   this tool provides a coordinate system to analyze a class of non - gaussian input distributions that are invariant over gaussian networks.
cotunneling transport through quantum dots weakly coupled to non - collinearly magnetized leads is analyzed theoretically by means of the real - time diagrammatic technique. the electric current, dot occupations, and dot spin are calculated in the coulomb blockade regime and for arbitrary magnetic configuration of the system.   it is shown that an effective exchange field exerted on the dot by ferromagnetic leads can significantly modify the transport characteristics in non - collinear magnetic configurations, in particular the zero - bias anomaly found recently for antiparallel configuration.   for asymmetric anderson model, the exchange field gives rise to precession of the dot spin, which leads to a nonmonotonic dependence of the differential conductance and tunnel magnetoresistance on the angle between magnetic moments of the leads.   an enhanced differential conductance and negative tmr are found for certain non - collinear configurations.
the radiative recombination of a free electron into an excited state of a bare, high@xmath0 ion is studied, together with its subsequent decay, within the framework of the density matrix theory and dirac s relativistic equation.   special attention is paid to the polarization and angular correlations between the recombination and the decay photons. in order to perform a systematic analysis of these correlations the general expression for the double   differential recombination cross section is obtained by making use of the resonance approximation.   based on this expression, detailed computations for the linear polarization of x  ray photons emitted in the ( e, 2@xmath1 ) two  step recombination of uranium ions u@xmath2 are carried out for a wide range of projectile energies.
we report the detection of the emission line he  ii  @xmath04686   in @xmath1 carinae. the equivalent width of this line is @xmath2100 m  along most of the 5.5yr cycle and jumps to @xmath2900 m  just before phase 1.0, followed by a brief disappearance.   the similarity between the intensity variations of this line and of the x  ray light curve is remarkable, suggesting that they are physically connected.   we show that the number of ionizing photons in the ultraviolet and soft x  rays, expected to be emitted in the shock wave from the colliding winds, is of the order of magnitude required to produce the he  ii emission via photoionization.    the emission is clearly blueshifted when the line is strong.   the radial velocity of the line is generally 100 km  s@xmath3, decreases steadily just before the event, and reaches 400 km  s@xmath3 at ph@xmath41.001. at this point, the velocity gradient suddenly changes sign, at the same time that the emission intensity drops to nearly zero.   possible scenarios for explaining this emission are briefly discussed.   the timing of the peak of he  ii intensity is likely to be associated to the periastron and may be a reliable fiduciary mark, important for constraining the orbital parameters.
we investigate the applicability of inhomogeneous absorber models in the formation of agn outflow absorption - troughs.   the models we explore are limited to monotonic gradients of absorbing column densities in front of a finite emission source.   our main finding is that simple power - law and gaussian distributions are hard pressed to fit the mrk  279 high - quality uv outflow data.   an acceptable fit for the  troughs can only be obtained by assuming unrealistic optical depth values ( upward of 100 ).   the strongest constraints arise from the attempt to fit the lyman series troughs. in this case   it is evident that even allowing for complete freedom of both the power - law exponent and the optical depth as a function of velocity can not yield an acceptable fit.   in contrast, partial covering models do yield good fits for the lyman series troughs.   we conclude that monotonic inhomogeneous absorber models that do not include a sharp edge in the optical depth distribution across the source are not an adequate physical model to explain the trough formation mechanism for the outflow observed in mrk  279.   = 9.0 in    946pg  0946 + 301   2ergss@xmath0@xmath1 3cm^-3 2cm^-2 5007@xmath2
we compute the casimir interaction between a plane and a sphere, the configuration employed in the most precise experiments.   the scattering formula is developed by taking a suitably chosen plane - wave and multipole basis and is valid for arbitrary values of the sphere radius, inter - plate distance, temperature and arbitrary dielectric functions for both sphere and plate. our analytical and numerical results for metallic surfaces show a non - trivial interplay between the effects of curvature, temperature, finite conductivity and dissipation.
we consider the casimir interaction between a ferromagnetic and a non - magnetic mirror, and show how the casimir effect gives rise to a magnetic anisotropy in the ferromagnetic layer.   the anisotropy is out - of - plane if the non - magnetic plate is optically isotropic.   if the non - magnetic plate shows a uniaxial optical anisotropy ( with optical axis in the plate plane ), we find an in - plane magnetic anisotropy. in both cases,   the energetically most favorable magnetization orientation is given by the competition between polar, longitudinal and transverse contributions to the magneto - optical kerr effect, and will therefore depend on the interplate distance.   numerical results will be presented for a magnetic plate made out of iron, and non - magnetic plates of gold ( optically isotropic ), quartz, calcite and barium titanate ( all uniaxially birefringent ).
we report three rxte / pca observations of the low - mass x - ray binary 4u  0614 + 09.   they show strong ( @xmath030% rms ) band - limited noise with a cut - off frequency varying between 0.7 and 15  hz in correlation with the x - ray flux, @xmath1.   we observe two non - simultaneous 1115% ( rms ) khz peaks near 728 and 629  hz in the power spectra of two of our observations when @xmath210@xmath3erg  @xmath4  s@xmath5 ( 210  kev ), but find no qpo ( @xmath66% rms ) when @xmath1 is half that.   we suggest that count rate may not be a good measure for @xmath7 even in sources as intrinsically weak as 4u  0614 + 09, and that qpo frequency and noise cutoff frequency track @xmath8 more closely than count rate.   the qpo increases in rms amplitude from ( 11@xmath91.3)% at 3 to ( 37@xmath912)% at 23  kev ; the fractional amplitude of the band - limited noise is energy - independent.   this suggests different sites of origin for these two phenomena.   the spectrum of the oscillating flux roughly corresponds to a black body with temperature ( 1.56@xmath90.2 )  kev and radius ( 500@xmath9200 )  m ( other models fit as well ), which might indicate the oscillations originate at a small region on the neutron star surface.
with excellent angular resolution, good energy resolution and broad energy band, the chandra acis is the best instrument for studying the x - ray halos around some galactic x - ray point sources caused by the dust scattering of x - rays in the interstellar medium.   however, the direct images of bright sources obtained with acis usually suffer from severe pile - up. making use of the fact that an isotropic image could be reconstructed from its projection into any direction  , we can reconstruct the images of the x - ray halos from the data obtained with the hetgs and/or in cc mode.   these data have no or less serious pile - up and enable us to take full advantage of the excellent angular resolution of chandra. with the reconstructed high resolution images, we can probe the x - ray halos as close as 1@xmath0 to their associated point sources. applying this method to cygnus x-1   observed with chandra hetgs in cc mode, we derived an energy dependent radial halo flux distribution and concluded that, in a circular region ( 2@xmath1 in radius ) centered at the point source : ( 1 ) relative to the total intensity, the fractional halo intensity ( fhi ) is about 15% at @xmath21  kev and drops to about 5% at @xmath26  kev ; ( 2 ) about 50% of the halo photons are within the region of a radius less than 40@xmath0 ; and ( 3 ) the spectrum of the point source is slightly distorted by the halo contamination.
the first - order irreversible phase transitions ( ipt ) of the yaldran - khan model ( yaldran - khan, j. catal. *   131 *, 369, 1991 ) for the @xmath0 reaction is studied using the constant coverage ( cc ) ensemble and performing epidemic simulations.   the cc method allows the study of hysteretic effects close to coexistence as well as the location of both the upper spinodal point and the coexistence point.   epidemic studies show that at coexistence the number of active sites decreases according to a ( short - time ) power law followed by a ( long - time ) exponential decay.   it is concluded that first - order ipt s share many characteristic of their reversible counterparts, such as the development of short ranged correlations, hysteretic effects, metastabilities, etc.  .5 cm.5 cm 21truecm 16truecm
we study nano - pattern formation in a stochastic model for adsorption - desorption processes with interacting adsorbate and hyperbolic transport caused by memory effects. it is shown that at early stages the system manifests pattern selection processes.   stationary stable patterns of nano - size are analyzed.   it was found that multiplicative noise satisfying fluctuation - dissipation relation can induce re - entrant pattern formation related to non - equilibrium transitions. according to obtained fokker - planck equation kinetics of island sizes in a quasi - stationary limit   is discussed.   analytical results are compared with computer simulations.
we analyze the effect of the long - range interaction on the transport properties through ordered and disordered one - dimensional metallic nanoparticle arrays.   we discuss how the threshold voltage, the i - v curves and the voltage drop through the array are modified as compared to the case in which interactions are restricted to charges placed on the same island.   we show that some of these modifications are due to finite interactions between charges in different nanoparticles while other ones are due to interactions between charges in the islands and those at the electrodes, what produces a polarization potential drop through the array.   we study the screening of the disorder potential due to charged impurities trapped in the substrate and find that long - range interactions introduce correlations between the disorder potentials of neighboring islands.
we present mocassin 2d photoionisation and dust radiative transfer models of a prototypical t  tauri disk irradiated by x - rays from the young pre - main sequence star.   the calculations demonstrate a layer of hot gas reaching temperatures of @xmath010@xmath1k at small radii and @xmath010@xmath2k at a distance of 1  au.   the gas temperatures decrease sharply with depth, but appear to be completely decoupled from dust temperatures down to a column depth of @xmath310@xmath4.   we predict that several fine - structure and forbidden lines of heavy elements, as well as recombination lines of hydrogen and helium, should be observable with current and future instrumentation, although optical lines may be smothered by the stellar spectrum. predicted line luminosities are given for the the brightest collisionally excited lines ( down to @xmath010@xmath5l@xmath6 ), and for recombination transitions from several levels of h  i and he  i.    the mass loss rate due to x - ray photoevaporation estimated from our models is of the order of @xmath7  m@xmath6 yr@xmath8, implying a dispersal timescale of a few myr for a disk of mass 0.027  m@xmath6, which is the mass of the disk structure model we employed.   we discuss the limitations of our model and highlight the need for further calculations that should include the simultaneous solution of the 2d radiative transfer problem and the 1d hydrostatic equilibrium in the polar direction.
using two - dimensional particle - in - cell simulations, we examine how an externally applied strong magnetic impacts proton acceleration in laser - irradiated solid - density targets.   we find that a kt - level external magnetic field can sufficiently inhibit transverse transport of hot electrons in a flat laser - irradiated target.   while the electron heating by the laser remains mostly unaffected, the reduced electron transport during proton acceleration leads to an enhancement of maximum proton energies and the overall number of energetic protons.   the resulting proton beam is much better collimated compared to a beam generated without applying a kt - level magnetic field.   a factor of three enhancement of the laser energy conversion efficiency into multi - mev protons is another effect of the magnetic field.   the required kt magnetic fields are becoming feasible due to a significant progress that has been made in generating magnetic fields with laser - driven coils using ns - long laser pulses.   the predicted improved characteristics of laser - driven proton beams would be critical for a number of applications.
we explicitly build a generalized local - density approximation ( glda ) correlation functional based on one - dimensional ( 1d ) uniform electron gases ( uegs ).   the fundamental parameters of the glda  a generalization of the widely - known local - density approximation ( lda ) used in density - functional theory ( dft )  are the electronic density @xmath0 and a newly - defined two - electron local parameter called the hole curvature @xmath1.   the uegs considered in this study are finite versions of the conventional infinite homogeneous electron gas and consist of @xmath2 electrons on an infinitely thin wire with periodic boundary conditions.   we perform a comprehensive study of these finite uegs at high, intermediate and low densities using perturbation theory and quantum monte carlo calculations.   we show that the present glda functional yields accurate estimates of the correlation energy for both weakly and strongly correlated one - dimensional systems and can be easily generalized to higher - dimensional systems.
recently, an extension of from one to multiple datasets, termed, has been the subject of significant research interest. has also been shown to be a generalization of hotelling s canonical correlation analysis. in this paper, we provide the identification conditions for a general formulation, which accounts for linear, nonlinear, and sample - to - sample dependencies.   the identification conditions are a generalization of previous results for and for when samples are.   furthermore, a principal aim of is the identification of dependent sources between datasets.   thus, we provide the additional conditions for when the arbitrary ordering of the sources within each dataset is common.   performance bounds in terms of the are also provided for the demixing matrices and.   the performance of two algorithms are compared to the theoretical bounds.
the entanglement entropy of the integer quantum hall states satisfies the area law for smooth domains with a vanishing topological term. in this paper   we consider polygonal domains for which the area law acquires a constant term that only depends on the angles of the vertices and we give a general expression for it.   we study also the dependence of the entanglement spectrum on the geometry and give it a simple physical interpretation.    0.2 cm        c
nonthermal fixed points of the dynamics of a dilute degenerate bose gas far from thermal equilibrium are analysed in two and three spatial dimensions.   universal power - law distributions, previously found within a nonperturbative quantum - field theoretical approach and recently shown to be related to vortical dynamics and superfluid turbulence [ phys.   rev.   b * 84 *, 020506(r ) ( 2011 ) ], are studied in detail.   the results imply an interpretation of the scaling behavior in terms of independent vortex excitations of the superfluid and show that the statistics of topological excitations can be described in the framework of wave turbulence.   the particular scaling exponents observed in the single - particle momentum distributions are found to be consistent with irreversibility as well as conservation laws obeyed by the wave interactions.   moreover, long - wavelength acoustic excitations of the vortex - bearing condensate, driven by vortex annihilations, are found to follow a nonthermal power law.   considering vortex correlations in a statistical model, the long - time departure from the nonthermal fixed point is related to vortex - antivortex pairing.   the studied nonthermal fixed points are accessible in cold - gas experiments.   the results shed light on fundamental aspects of superfluid turbulence and have strong potential implications for related phenomena, e.g., in early - universe inflation or quark - gluon plasma dynamics.
we present radio observations of the black hole candidate x - ray binary gx 339 - 4 with the australia telescope compact array.   mapping of the highest resolution 3.5 cm data reveals a jet - like extension, which if confirmed would be the first detection of a radio jet from a _ persistent _ black - hole candidate system.   no evidence is found for associated structures such as bow shocks or jet lobes on larger scales.   the spectral energy distribution from 22 - 3 cm is relatively flat, suggesting emission is dominated by a compact absorbed core.   binaries : close  stars : individual : gx339 - 4  radio continuum : stars
asteroseismology is a powerful method for determining fundamental properties of stars.   we report the first application to a metal - poor object, namely the subgiant star.   we measured precise velocities from two sites, allowing us to detect oscillations and infer a large frequency separation of @xmath0hz. combining this value with the location of the star in the h - r diagram and comparing with standard evolutionary models  , we were able to place constraints on the stellar parameters.   in particular, our results indicate that has a low mass ( @xmath1 ) and is at least 9gyr old.
we revisit the problem of the critical velocity of a clean one - dimensional superconductor. at the level of mean - field theory, we find that the zero - temperature value of the critical velocity  the uniform velocity of the superfluid condensate at which the superconducting state becomes unstable  is a factor of @xmath0 smaller than the landau critical velocity.   this is in contrast to a prior finding, which held that the critical velocity is equal to the landau critical velocity.   the smaller value of the critical velocity, which our analysis yields, is the result of a pre - emptive clogston - chandrasekhar  like discontinuous phase transition, and is an analog of the threshold value of the uniform exchange - field of a superconductor, previously investigated by sarma and by maki and tsuneto.   we also consider the impact of nonzero temperature, study critical currents, and examine metastability and its limits in the temperature versus flow - velocity phase diagram.   in addition, we comment on the effects of electron scattering by impurities.
we discuss the prospect of studying physics at short distances, such as planck length or gut scale, using supersymmetry as a probe.   supersymmetry breaking parameters contain information on all physics below the scale where they are induced.   we will gain insights into grand unification ( or in some cases string theory ) and its symmetry breaking pattern combining measurements of gauge coupling constants, gaugino masses and scalar masses.   once the superparticle masses are known, it removes the main uncertainty in the analysis of proton decay, flavor violation and electric dipole moments  . we will be able to discuss the consequence of flavor physics at short distances quantitatively.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    january 16, 1998 ucb - pth-98/05 +   hep - ph/9801331 +   .1 in    * probing physics at short distances + with supersymmetry *    0.3 in    hitoshi murayama    0.05 in    _ theoretical physics group + ernest orlando lawrence berkeley national laboratory + university of california, berkeley, california 94720 _    0.05 in    and    0.05 in    _ department of physics + university of california, berkeley, california 94720 _
around the world, several scientific projects share the interest of a global network of small cherenkov telescopes for monitoring observations of the brightest blazars - the dwarf network. a small  , ground based, imaging atmospheric cherenkov telescope of last generation is intended to be installed and operated in romania as a component of the dwarf network. to prepare the construction of the observatory,   two support projects have been initiated. within the framework of these projects,   we have assessed a number of possible sites where to settle the observatory. in this paper   we submit a brief report on the general characteristics of the best four sites selected after the local infrastructure, the nearby facilities and the social impact criteria have been applied.   site testing, gamma - ray cherenkov telescopes, very high energy gamma rays
we develop a strong coupling approach for a general lattice problem.   we argue that this strong coupling perspective represents the natural framework for a generalization of the dynamical mean field theory ( dmft ).   the main result of this analysis is twofold : 1 ) it provides the tools for a unified treatment of any non - local contribution to the hamiltonian. within our scheme,   non - local terms such as hopping terms, spin - spin interactions, or non - local coulomb interactions are treated on equal footing.   2 ) by performing a detailed strong - coupling analysis of a generalized lattice problem, we establish the basis for possible clean and systematic extensions beyond dmft. to this end, we study the problem using three different perspectives.   first, we develop a generalized expansion around the atomic limit in terms of the coupling constants for the non - local contributions to the hamiltonian. by analyzing the diagrammatics associated with this expansion, we establish the equations for a generalized dynamical mean - field theory ( g - dmft ).   second, we formulate the theory in terms of a generalized strong coupling version of the baym - kadanoff functional.   third, following pairault, snchal, and tremblay@xcite, we present our scheme in the language of a perturbation theory for canonical fermionic and bosonic fields and we establish the interpretation of various strong coupling quantities within a standard perturbative picture.
this paper considers nonlinear dynamics of plasma oscillations modeled by a forced modified van der pol - duffing oscillator.   these plasma oscillations are described by a nonlinear differential equation of the form @xmath0 the amplitudes of the forced harmonic, superharmonic and subharmonic oscillatory states are obtained using the harmonic balance technique and the multiple time scales methods.   admissible values of the amplitude of the external strength are derived.   bifurcation sequences displayed by the model for each type of oscillatory states are performed numerically through the fourth order runge- kutta scheme.
some developments of nuclear - structure physics uniquely related to copenhagen school are sketched based on theoretical considerations versus experimental findings and one - particle versus collective aspects. based on my personal overview   i pick up the following topics ; ( 1 ) study of vibration in terms of particle - vibration coupling ; ( 2 ) one - particle motion in deformed and rotating potentials, and yrast spectroscopy in high - spin physics ; ( 3 ) triaxial shape in nuclei : wobbling motion and chiral bands ; ( 4 ) nuclear structure of drip line nuclei : in particular, shell - structure ( or magic numbers ) change and spherical or deformed halo phenomena ; ( 5 ) shell structure in oblate deformation.
retrieval of records on disk is well - known to be at the heart of many database problems.   we show that the corresponding movement of records in main memory has now become a severe bottleneck for many database operations.   this is due to the stagnating latency of main memory, even while cpu speed, main memory bandwidth, and disk speed all continue to improve. as a result  , record movement has become the dominant cost in main memory sorting.   we present a new algorithm for fast record retrieval, _ distribute - probe - gather _, or dpg.   dpg has important applications both in sorting and in joins.   current main memory sorting algorithms split their work into three phases : extraction of key - pointer pairs ; sorting of the key - pointer pairs ; and copying of the original records into the destination array according the sorted key - pointer pairs.   the copying in the last phase dominates today s sorting time.   hence, the use of dpg in the third phase provides an accelerator for existing sorting algorithms.   dpg also provides two new join methods for foreign key joins : dpg - move join and dpg - sort join.   the resulting join methods with dpg are faster because dpg join is cache - efficient and at the same time dpg join avoids the need for sorting or for hashing.   the ideas presented for foreign key join can also be extended to faster record pair retrieval for spatial and temporal databases.
we present a detailed analysis of the bell measurement scheme proposed in lee _   et al. _   [ phys.   rev.   lett. * 114 *, 113603 ( 2015 ) ] based on a logical qubit using greenberger - horne - zeilinger entanglement of photons.   the success probability of the proposed bell measurement can be made arbitrarily high using only linear optics as the number of photons in a logical qubit increases.   we compare our scheme with all the other proposals, using single - photon qubits, coherent - state qubits or hybrid qubits, suggested to enhance the efficiency of the bell measurement. as a remarkable advantage, our scheme requires only photon on - off measurements, while photon number resolving detectors are necessary for all the other proposals.   we find that the scheme based on coherent - state qubits shows the best performance with respect to the attained success probability in terms of the average number of photons used in the process, while our scheme outperforms the schemes using single - photon qubits.   we finally show that efficient quantum communication and fault - tolerant quantum computation can be realized using our approach.   = 10000
we derive the expressions of the vector and axial current from a chiral lagrangian restricted to nucleons and pions.   they display mixing terms between the axial and vector currents.   we study the modifications in the nuclear medium of the coupling constants of the axial current, namely the pion decay constant and the nucleonic axial one due to the requirements of chiral symmetry.   we express the renormalizations in terms of the local scalar pion density.   the latter also governs the quark condensate evolution and we discuss the link between this evolution and the renormalizations. in the case of the nucleon axial coupling constant   this renormalization corresponds to a new type of pion exchange currents, with two exchanged pions.   we give an estimate for the resulting quenching.   although moderate it helps explaining the quenching experimentally observed.   = 0.1 cm    = 40 mm    pacs numbers : 12.39.fe 24.85.+p 23.40.bw    = 30pt
we present a mechanism for amplitude death in coupled nonlinear dynamical systems on a complex network having interactions with a common environment - like external system. we develop a general stability analysis that is valid for any network topology and   obtain the threshold values of coupling constants for the onset of amplitude death.   an important outcome of our study is a universal relation between the critical coupling strength and the largest non - zero eigenvalue of the coupling matrix.   our results are fully supported by the detailed numerical analysis for different network topologies.
we selected and studied 180 pairs with @xmath0 and @xmath1 containing markarian ( mrk ) galaxies to investigate the dependence of galaxies integral parameters, star - formation ( sf ) and active galactic nuclei ( agn ) properties on kinematics of pairs, their structure and large - scale environments.   projected radial separation @xmath2 and perturbation level @xmath3 are better measures of interaction strength than @xmath4.   the latter correlates with the density of large - scale environment and with the morphologies of galaxies.   both galaxies in a pair are of the same nature, the only difference is that mrk galaxies are usually brighter than their neighbors  . specific star formation rates ( ssfr ) of galaxies in pairs with smaller @xmath2 or @xmath5 is in average 0.5  dex higher than that of galaxies in pairs with larger @xmath2 or @xmath5.   closeness of a neighbor with the same and later morphological type increases the ssfr, while earlier - type neighbors do not increase ssfr.   major interactions / mergers trigger sf and agn more effectively than minor ones. the fraction of agns is higher in more perturbed pairs and pairs with smaller @xmath2.   agns typically are in stronger interacting systems than star - forming and passive galaxies.   there are correlations of both ssfrs and spectral properties of nuclei between pair members.
we present xmm - newton spectra of the seyfert 2 galaxy iras 00521 - 7054. a strong feature at @xmath0 kev ( observer s frame )   can be formally fitted with a strong ( ew=@xmath1  kev in the rest frame ) and broad fe k@xmath2 line, extending down to 3  kev.   the underlying x - ray continuum could be fitted with an absorbed powerlaw ( with @xmath3 = 1.8@xmath4 and n@xmath5 = 5.9@xmath6 @xmath7 @xmath8 ) plus a soft component. if due to relativistically smeared reflection by an x - ray illuminated accretion disk, the spin of the supermassive black hole is constrained to be @xmath9 ( errors at 90% confidence level for one interesting parameter ), and the accretion system is viewed at an inclination angle of 37@xmath10@xmath11.   this would be the first type 2 agn reported with strong red  wing detected which demands a fast rotating smbh.   the unusually large ew would suggest that the light bending effect is strong in this source.   alternatively, the spectra could be fitted by a dual absorber model ( though with a global @xmath12 higher by @xmath0 for 283 d.o.f ) with n@xmath13 = 7.0@xmath14 @xmath15 @xmath16 @xmath8 covering 100% of the x - ray source, and n@xmath17 = 21.7@xmath18@xmath7 @xmath8 covering 71%, which does not require an extra broad fe k@xmath2 line.
the recently discovered high - energy transient sw j1644 + 57 is thought to arise from the tidal disruption of a passing star by a dormant massive black hole. the long - term, bright radio emission of sw j1644 + 57   is believed to result from the synchrotron emission of the blast wave produced by an outflow expanding into the surrounding medium. using the detailed multi - epoch radio spectral data, we are able to determine the total number of radiating electrons in the outflow at different times, and further the evolution of the cross section of the outflow with time.   we find that the outflow gradually transits from a conical jet to a cylindrical one at later times.   the transition may be due to collimation of the outflow by the pressure of the shocked jet cocoon that forms while the outflow is propagating in the ambient medium.   since cylindrical jets usually exist in agns and extragalactic jets, this may provide independent evidence that sw j1644 + 57 signals the onset of an agn.
we use 1 + 1 dimensional large @xmath0 gross - neveu models as a laboratory to derive microscopically effective lagrangians for positive energy fermions only.   when applied to baryons, the euler - lagrange equation for these effective theories assumes the form of a non - linear dirac equation.   its solution reproduces the full semi - classical results including the dirac sea to any desired accuracy.   dynamical effects from the dirac sea are encoded in higher order derivative terms and multi - fermion interactions with perturbatively calculable, finite coefficients.   characteristic differences between models with discrete and continuous chiral symmetry are observed and clarified.
single layer core / shell structures consisting of graphene as core and hexagonal boron nitride as shell are studied using first - principles plane wave method within density functional theory.   electronic energy level structure is analysed as a function of the size of both core and shell.   it is found that the confinement of electrons in two dimensional graphene quantum dot is reduced by the presence of boron nitride shell.   the energy gap is determined by the graphene states.   comparison of round, hexagonal, rectangular and triangular core / shell structures reveals that their electronic and magnetic states are strongly affected by their geometrical shapes. the energy level structure,   energy gap and magnetic states can be modified by external charging.   the core part acts as a two - dimensional quantum dot for both electrons and holes.   the capacity of extra electron intake of these quantum dots is shown to be limited by the coulomb blockade in two - dimension.
we study brane configurations that give rise to large-@xmath0 gauge theories with eight supersymmetries and no hypermultiplets.   these configurations include a variety of wrapped, fractional, and stretched branes or strings. the corresponding spacetime geometries which we study have a distinct kind of singularity known as a repulson.   we find that this singularity is removed by a distinctive mechanism, leaving a smooth geometry with a core having an enhanced gauge symmetry.   the spacetime geometry can be related to large-@xmath0 seiberg   witten theory.   epsf    3.7 in    * gauge theory and the excision of repulson singularities *    * clifford v. johnson, amanda w. peet, joseph polchinski *    @xmath1school of natural sciences    institute for advanced study    princeton, nj 08540, u.s.a.   @xmath1centre for particle theory    department of mathematical sciences    university of durham, durham dh1 3le, u.k.   @xmath2institute for theoretical physics    university of california    santa barbara, ca  93106 - 4030, u.s.a.
by exploring some elementary consequences of the covariance of maxwell s equations under general coordinate transformations, we show that even though inertial observers can detect electromagnetic radiation emitted from a uniformly accelerated charge, comoving observers will see only a static electric field  . this analysis can add insight into one of the most celebrated paradoxes of the last century.
ngc 2915 is a nearby blue compact dwarf with the  properties of a late - type spiral.   its large, rotating  disk ( extending out to @xmath0  @xmath1-band scale lengths ) and apparent lack of stars in the outer  disk make it a useful candidate for dark matter studies.   new  synthesis observations of ngc 2915 have been obtained using the australian telescope compact array.   these data are combined with high - quality 3.6  imaging from the _ spitzer _ infrared nearby galaxies survey.   the central regions of the  disk are shown to consist of two distinct  concentrations with significantly non - gaussian line profiles.   we fit a tilted ring model to the  velocity field to derive a rotation curve.   this is used as input for mass models that determine the contributions from the stellar and gas disks as well as the dark matter halo.   the galaxy is dark - matter - dominated at nearly all radii. at the last measured point of the rotation curve,   the total mass to blue light ratio is @xmath2 140 /l@xmath3, making ngc  2915 one of the darkest galaxies known.   we show that the stellar disk can not account for the steeply - rising portion of the observed rotation curve.   the best - fitting dark matter halo is a pseudo - isothermal sphere with a core density @xmath4  pc@xmath5 and a core radius @xmath6  kpc.       galaxies  dwarf, haloes, kinematics and dynamics
we report on _ ab initio _ time - dependent spin dynamics simulations for a two - center magnetic molecular complex based on time - dependent non - collinear spin density functional theory.   in particular, we discuss how the dynamical behavior of the _ ab initio _ spin - density in the time - domain can be mapped onto a model hamiltonian based on the classical heisenberg spin - spin interaction @xmath0. by analyzing individual localized - spin trajectories, extracted from the spin - density evolution,   we demonstrate a novel method for evaluating the effective heisenberg exchange coupling constant, @xmath1, from first principles simulations.   we find that @xmath1, extracted in such a new dynamical way, agrees quantitatively to that calculated by the standard density functional theory broken - symmetry scheme.
synthetic spin - orbit coupling in ultracold atomic gases can be taken to extremes rarely found in solids.   we study a two dimensional hubbard model of bosons in an optical lattice in the presence of spin - orbit coupling strong enough to drive direct transitions from mott insulators to superfluids. here   we find phase - modulated superfluids with finite momentum that are generated entirely by spin - orbit coupling.   transitions between different superfluids are also found to be first - order.   we investigate the rich periodic structure of the phases of the superfluids, which may be directly probed using time - of - flight imaging of the spin - dependent momentum distribution.
a system of non - intersecting squared bessel processes is considered which all start from one point and they all return to another point. under the scaling of the starting and ending points   when the macroscopic boundary of the paths touches the hard edge, a limiting critical process is described in the neighbourhood of the touching point which we call the hard edge tacnode process.   we derive its correlation kernel in an explicit new form which involves airy type functions and operators that act on the direct sum of @xmath0 and a finite dimensional space. as the starting points of the squared bessel paths   are set to @xmath1, a cusp in the boundary appears.   the limiting process is described near the cusp and it is called the hard edge pearcey process.   we compute its multi - time correlation kernel which extends the existing formulas for the single - time kernel.   our pre - asymptotic correlation kernel involves the ratio of two toeplitz determinants which are rewritten using a borodin  okounkov type formula.
after reviewing the concept of vison excitations in @xmath0 dimer liquids, we study the liquid - crystal transition of the quantum dimer model on the triangular lattice by means of a semiclassical spin - wave approximation to the dispersion of visons in the context of a  soft - dimer " version of the model.   this approach captures some important qualitative features of the transition : continuous nature of the transition, linear dispersion at the critical point, and @xmath1 symmetry - breaking pattern. in a second part  , we present a variational calculation of the vison dispersion relation at the rk point which reproduces the qualitative shape of the dispersion relation and the order of magnitude of the gap.   this approach provides a simple but reliable approximation of the vison wave functions at the rk point.
to further study the `` pygmy '' resonance phenomena in the photon strength function, we reanalyzed the two - step cascade data for the target nucleus @xmath0au using the dubna group approach.   the range of obtained values allows for meaningful conclusions : the level density at low excitation energy shows a step - like behavior ; the electric dipole photon strength function has a broad maximum around @xmath1 mev and is not typical of a `` pygmy '' resonance ; the level density below @xmath2 also demonstrates step - like behavior.    * reanalysis of the process of the cascade gamma decay of @xmath3au compound state * +     a.m. sukhovoj, v.a.   khitrov +    _ frank laboratory of neutron physics, joint institute for nuclear research, 141980, dubna, russia   _ +     b.e.   crawford, s.l.   stephenson + _ gettysburg college, 300 n. washington street.   gettysburg pa 17325, usa _
recent astronomical observations indicate that the universe is in the phase of accelerated expansion.   there are many cosmological models which explain this phenomenon, but should we prefer those models over the simplest one  @xmath0cdm model? according to the occam s razor principle   if all models describe the observations equally well we should prefer the simplest one.   we consider the model comparison methods which involve such rules : the akaike information criterion ( aic ), bayesian information criterion ( bic ) and bayesian evidence to compare the @xmath0cdm model with its generalisation where the interaction between dark matter and dark energy is allowed.   the analyses based on the aic and bayesian evidence indicate that there is only a weak evidence in favour of the @xmath0cdm model over its generalisation, while those based on bic quantity indicate the strong evidence in favour the simpler model.   we also calculate some quantity which measure the effective number of model parameters that the given data can constrain.   this value is used to compare the concordance lcdm model with its generalization basing on the extended interpretation of continuity condition - interacting @xmath0cdm cosmology.   we conclude that data set are not enough informative to constrain all parameters allows to vary in the models.
we consider arbitrary orderings of the edges entering each vertex of the ( downward directed ) pascal graph.   each ordering determines an adic ( bratteli - vershik ) system, with a transformation that is defined on most of the space of infinite paths that begin at the root.   we prove that for every ordering the coding of orbits according to the partition of the path space determined by the first three edges is essentially faithful, meaning that it is one - to - one on a set of paths that has full measure for every fully supported invariant probability measure.   we also show that for every @xmath0 the subshift that arises from coding orbits according to the first @xmath0 edges is topologically weakly mixing.   we give a necessary and sufficient condition for any adic system to be topologically conjugate to an odometer and use this condition to determine the probability that a random order on a fixed diagram, or a diagram constructed at random in some way, is topologically conjugate to an odometer.   we also show that the closure of the union over all orderings of the subshifts arising from codings of the pascal adic by the first edge has superpolynomial complexity, is not topologically transitive, and has no periodic points besides the two fixed points, while the intersection over all orderings consists of just four orbits.
an experiment which could decide against the copenhagen interpretation of quantum mechanics has been proposed by k. popper and, subsequently, it has been criticized by m.j.   collett and r. loudon. here   we show that both the above mentioned arguments are not correct because they are based on a misuse of basic quantum rules.
we show that any number of parties can coherently exchange any one pure quantum state for another, without communication, given prior shared entanglement.   two applications of this fact to the study of multi - prover quantum interactive proof systems are given.   first, we prove that there exists a one - round two - prover quantum interactive proof system for which no finite amount of shared entanglement allows the provers to implement an optimal strategy.   more specifically, for every fixed input string, there exists a sequence of strategies for the provers, with each strategy requiring more entanglement than the last, for which the probability for the provers to convince the verifier to accept approaches  1.   it is not possible, however, for the provers to convince the verifier to accept with certainty with a finite amount of shared entanglement.   the second application is a simple proof that multi - prover quantum interactive proofs can be transformed to have near - perfect completeness by the addition of one round of communication.
it has recently been pointed out that the geometric quantum discord, as defined by the hilbert - schmidt norm ( @xmath0-norm ), is not a good measure of quantum correlations, since it may increase under local reversible operations on the unmeasured subsystem. here, we revisit the geometric discord by considering general schatten @xmath1-norms, explicitly showing that the 1-norm is the only @xmath1-norm able to define a consistent quantum correlation measure.   in addition, by restricting the optimization to the tetrahedron of two - qubit bell - diagonal states, we provide an analytical expression for the 1-norm geometric discord, which turns out to be equivalent to the negativity of quantumness.   we illustrate the measure by analysing its monotonicity properties and by considering the ground state of quantum spin chains.
we consider a modified action functional with a non - minimum coupling between the scalar curvature and the matter lagrangian, and study its consequences on stellar equilibrium.   particular attention is paid to the validity of the newtonian regime, and on the boundary and exterior matching conditions, as well as on the redefinition of the metric components.   comparison with solar observables is achieved through numerical analysis, and constraints on the non - minimum coupling are discussed  .    0.5 cm    0.2 cm    0.2 cm    0.2 cm    0.5 cm
the ground state carrier dynamics in self - assembled ( in, ga)as / gaas quantum dots has been studied using time - resolved photoluminescence _ and _ transmission. by varying the dot design with respect to confinement and doping,   the dynamics is shown to follow in general a non - exponential decay. only for specific conditions in regard to optical excitation and carrier population, for example  , the decay can be well described by a mono - exponential form. for resonant excitation of the ground state transition a strong shortening of the luminescence decay time   is observed as compared to the non - resonant case.   the results are consistent with a microscopic theory that accounts for deviations from a simple two - level picture.
the hadron energy resolution of a highly granular calice analogue scintillator - steel hadronic calorimeter was studied using pion test beam data. the stochastic term contribution to the energy resolution   was estimated to be @xmath058%@xmath1. to improve an energy resolution,   local and global software compensation techniques were developed which exploit an unprecedented granularity of the calorimeter and are based on event - by - event analysis of the energy density spectra.   the application of either local or global software compensation technique results in reducing of stochastic term contribution down to @xmath045%@xmath1.   the achieved improvement of single particle energy resolution for pions is @xmath020% in the energy range from 10 to 80  gev.
we present a configuration interaction method optimized for fock - darwin states of two - dimensional quantum dots with an axially symmetric, parabolic confinement potential subject to a perpendicular magnetic field.   the optimization explicitly accounts for geometrical and dynamical symmetries of the fock - darwin single - particle states and for many - particle symmetries associated with the center - of - mass motion and with the total spin.   this results in a basis set of reduced size and improved accuracy.   the numerical results compare well with the quantum monte carlo and stochastic variational methods.   the method is illustrated by the evolution of a strongly correlated few - electron droplet in a magnetic field in the regime of the fractional quantum hall effect.
the winds of stars with very specific temperatures and luminosities are ideal for determining the magnitude and nature of mass loss in ob stars.   i identify these stars and analyze their wind lines.   the results are discussed within the context of recent findings which appear to indicate that the mass - loss rates of ob stars may as much as an order of magnitude less than commonly accepted values.
understanding decoherence in cryogenically - cooled rare - earth - ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications.   here we study the coherence properties in a weakly doped erbium silica glass fiber motivated by our recent observation of efficient and long - lived zeeman sublevel storage in this material and by its potential for applications at telecommunication wavelengths.   we analyze photon echo decays as well as the potential mechanisms of spectral diffusion that can be caused by coupling with dynamic disorder modes that are characteristic for glassy hosts, and by the magnetic dipole - dipole interactions between er@xmath0 ions.   we also investigate the effective linewidth as a function of magnetic field, temperature and time, and then present a model that describes these experimental observations.   we highlight that the operating conditions ( 0.6 k and 0.05 t ) at which we previously observed efficient spectral hole burning coincide with those for narrow linewidths ( 1 mhz )  an important property for applications that has not been reported before for a rare - earth - ion doped glass.
magnetic tunnel junction ( mtj ) spin torque oscillators ( sto ) have shown the potential to be used in a wide range of microwave and sensing applications.   to evaluate potential uses of mtj sto technology in various applications, an analytical model that can capture mtj sto s characteristics, while enabling system- and circuit - level designs, is of great importance.   an analytical model based on macrospin approximation is necessary for these designs since it allows implementation in hardware description languages.   this paper presents a new macrospin - based, comprehensive and compact mtj sto model, which can be used for various mtj stos to estimate the performance of mtj stos together with their application - specific integrated circuits. to adequately present the complete model, this paper   is divided into two parts. in part   i, the analytical model is introduced and verified by comparing it against measured data of three different mtj stos, varying the angle and magnitude of the magnetic field, as well as the dc biasing current.   the proposed analytical model is suitable for being implemented in verilog - a and used for efficient simulations at, circuit- and system - levels. in part ii, the full verilog - a implementation of the analytical model with accurate phase noise generation is presented and verified by simulations.   = 1    spin torque oscillator, magnetic tunnel junction, macrospin, analytical model.
we present a new model for the behavior of scattered time - dependent, asymmetric near - uv emission from the nearby ejecta of. using a 3-d hydrodynamical simulation of s binary colliding winds,   we show that the 3-d binary orientation derived by @xcite is capable of explaining the asymmetric near - uv variability observed in the _ hubble space telescope _   advanced camera for surveys / high resolution camera ( _ hst _ acs / hrc ) f220w images of @xcite.   models assuming a binary orientation with @xmath0 to @xmath1, @xmath2 to @xmath3, @xmath4 to @xmath5 are consistent with the observed f220w near - uv images.   we find that the hot binary companion does not significantly contribute to the near - uv excess observed in the f220w images.   rather, we suggest that a bore - hole effect and the reduction of fe ii optical depths inside the wind - wind collision cavity carved in the extended photosphere of the primary star lead to the time - dependent directional illumination of circum - binary material as the companion moves about in its highly elliptical orbit.
high - quality @xmath0-band spectra of point sources, deeply embedded in massive star - forming regions, have revealed a population of 20 young massive stars showing no photospheric absorption lines, but only emission lines.   the @xmath0-band spectra exhibit one or more features commonly associated with massive young stellar objects surrounded by circumstellar material : a very red color @xmath1, co bandhead emission, hydrogen emission lines ( sometimes doubly peaked ), and feii and/or mgii emission lines.   the co emission comes from a relatively dense ( @xmath2 ) and hot ( @xmath3  k ) region, sufficiently shielded from the intense uv radiation field of the young massive star.   modeling of the co - first overtone emission shows that the co gas is located within 5 au of the star.   the hydrogen emission is produced in an ionized medium exposed to uv radiation.   the best geometrical configuration is a dense and neutral circumstellar disk causing the co bandhead emission, and an ionized upper layer where the hydrogen lines are produced.   we argue that the circumstellar disk is likely a remnant of the accretion via a circumstellar disk.
theoretical, numerical and experimental results examining thermoviscous losses in sonic crystals are presented in this work, enabling the fabrication and characterization of an acoustic metamaterial absorber with complex - valued anisotropic inertia.   the formulations developed can be written with no unknown or empirical coefficients, due to the structured lattice of the sonic crystals and organized layering scheme, and it is shown that higher filling fraction arrangements can be used to provide a large enhancement in the loss factor. to accurately describe these structures in a realizable experimental configuration, confining structures are needed which modify the effective properties, due to the thermal and viscous boundary layer effects within the sonic crystal lattice.   theoretical formulations are presented which describe the effects of these confined sonic crystals, both individually and as part of an acoustic metamaterial structure, and is demonstrated experimentally in an acoustic impedance tube.   it is observed that confined sonic crystals demonstrate an increase in the viscous losses and a reduction in the effective bulk modulus, enabling better acoustic absorber performance through improved impedance matching and enhanced absorption.
we present the results of a high angular resolution study of the bl lac object markarian 501 in the radio band.   we consider data taken at 14 different epochs, ranging between 1.6ghz and 22ghz in frequency, and including new space vlbi observations obtained on 2001 march 5 and 6 at 1.6 and 5ghz.   we study the kinematics of the parsec - scale jet and estimate its bulk velocity and orientation with respect to the line of sight.   limb brightened structure in the jet is clearly visible in our data and we discuss its possible origin in terms of velocity gradients in the jet.   quasi - simultaneous multi - wavelength observations allow us to map the spectral index distribution and to compare it to the jet morphology.   finally, we estimate the physical parameters of the parsec - scale jet.
understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long - standing unsolved problem in theoretical physics.   black - hole mergers are monumental astrophysical events, releasing tremendous amounts of energy in the form of gravitational radiation, and are key sources for both ground- and space - based gravitational - wave detectors. the black - hole merger dynamics and the resulting gravitational waveforms can only be calculated through numerical simulations of einstein s equations of general relativity. for many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit could be simulated. recently, however, a series of dramatic advances in numerical relativity has allowed stable, robust black - hole merger simulations.   this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black - hole binary dynamics that is emerging is chronicled.   important applications of these fundamental physics results to astrophysics, to gravitational - wave astronomy, and in other areas are also discussed.
we present a model - independent method of quantifying galaxy evolution in high - resolution images, which we apply to the hubble deep field ( hdf ).   our procedure is to k - correct all pixels belonging to the images of a complete set of bright galaxies and then to replicate each galaxy image to higher redshift by the product of its space density, @xmath0, and the cosmological volume.   the set of bright galaxies is itself selected from the hdf, because presently the hdf provides the highest quality uv images of a redshift - complete sample of galaxies ( 31 galaxies with @xmath1, @xmath2, and for which @xmath3 is spread fairly ).   these galaxies are bright enough to permit accurate pixel - by - pixel k - corrections into the restframe uv ( @xmath4 @xmath5 ).   we match the shot noise, spatial sampling and psf smoothing of the hdf data, resulting in entirely empirical and parameter - free `` no - evolution '' deep fields of galaxies for direct comparison with the hdf.   in addition, the overcounting rate and the level of incompleteness can be accurately quantified by this procedure.   we obtain the following results.   faint hdf galaxies ( @xmath6 ) are much smaller, more numerous, and less regular than our `` no - evolution '' extrapolation, for any interesting geometry. a higher proportion of hdf galaxies `` dropout '' in both @xmath7 and @xmath8, indicating that some galaxies were brighter at higher redshifts than our `` cloned '' @xmath9 population.    &
we study the transport properties of a long non - uniform quantum wire where the electron - electron interactions and the density vary smoothly at large length scales.   we show that these inhomogeneities lead to a finite resistivity of the wire, due to a weak violation of momentum conservation in the collisions between electrons. estimating the rate of change of momentum associated with non - momentum - conserving scattering processes, we derive the expression for the resistivity of the wire in the regime of weakly interacting electrons and find a contribution linear in temperature for a broad range of temperatures below the fermi energy. by estimating the energy dissipated throughout the wire by low - energy excitations,   we then develop a different method for deriving the resistivity of the wire, which can be combined with the bosonization formalism.   this allows us to compare our results with previous works relying on an extension of the tomonaga - luttinger model to inhomogeneous systems.
we study the nucleon and three @xmath0 resonances properties in an effective linear realization chiral @xmath1 and @xmath2 symmetric lagrangian.   we place the nucleon fields into the so - called  naive " @xmath3 and  mirror " @xmath4 ( fundamental ) representations of @xmath5, two of each - distinguished by their @xmath2 chiral properties, as defined by an explicit construction of the nucleon interpolating fields in terms of three quark ( dirac ) fields.   we construct the most general one - meson - baryon chiral interaction lagrangian assuming various parities of these four nucleon fields.   we show that the observed masses of the four lowest lying nucleon states can be well reproduced with the effective lagrangian, after spontaneous symmetry breakdown, without explicit breaking of @xmath2 symmetry.   this does not mean that explicit @xmath2 symmetry breaking does not occur in baryons, but rather that it does not have a unique mass prediction signature that exists e.g. in the case of spinless mesons.   we also consider briefly the axial couplings with chiral representation mixing.
we present infrared images and spectra of comets 2p / encke, 67p / churyumov - gerasimenko, and c/2001  ht50 ( linear - neat ) as part of a larger program to observe comets inside of 5  au from the sun with the _ spitzer space telescope_. the nucleus of comet 2p / encke was observed at two vastly different phase angles ( 20 and 63 ).   model fits to the spectral energy distributions of the nucleus suggest comet encke s infrared beaming parameter derived from the near - earth asteroid thermal model may have a phase angle dependence.   the observed emission from comet encke s dust coma is best - modeled using predominately amorphous carbon grains with a grain size distribution that peaks near 0.4 , and the silicate contribution by mass to the sub - micron dust coma is constrained to @xmath0%. comet 67p / churyumov - gerasimenko   was observed with distinct coma emission in excess of a model nucleus at a heliocentric distance of 5.0  au.   the coma detection suggests that sublimation processes are still active or grains from recent activity remain near the nucleus.   comet c/2001   ht50 ( linear - neat ) showed evidence for crystalline silicates in the spectrum obtained at 3.2  au and we derive a silicate - to - carbon dust ratio of 0.6.   the ratio is an order of magnitude lower than that derived for comets 9p / tempel  1 during the _ deep impact _ encounter and c/1995  o1 ( hale - bopp ).
we investigate the equilibration and thermalization properties of quantum systems interacting with a finite dimensional environment. by exploiting the concept of time averaged states, we introduce a completely positive map which allows to describe in a quantitative way the dependence of the equilibrium state on the initial condition.   our results show that the thermalization of quantum systems is favored if the dynamics induces small system - environment correlations, as well as small changes in the environment, as measured by the trace distance.
microscopic flows are almost universally linear, laminar and stationary because reynolds number, @xmath0, is usually very small.   that impedes mixing in micro - fluidic devices, which sometimes limits their performance.   here we show that truly chaotic flow can be generated in a smooth micro - channel of a uniform width at arbitrarily low @xmath0, if a small amount of flexible polymers is added to the working liquid.   the chaotic flow regime is characterized by randomly fluctuating three - dimensional velocity field and significant growth of the flow resistance.   although the size of the polymer molecules extended in the flow may become comparable with the micro - channel width, the flow behavior is fully compatible with that in a table - top channel in the regime of elastic turbulence.   the chaotic flow leads to quite efficient mixing, which is almost diffusion independent. for macromolecules, mixing time in this microscopic flow   can be three to four orders of magnitude shorter than due to molecular diffusion.    2
the twin higgs model is the preeminent example of a theory of neutral naturalness, where the new particles that alleviate the little hierarchy problem are standard model ( sm ) singlets.   the most promising collider search strategy, based on rare higgs decays, is nevertheless not effective in significant regions of the parameter space of the low energy theory.   this underlines the importance of phenomenological studies on ultraviolet completions of the twin higgs model, which must lie at a scale lower than @xmath0-@xmath1 tev.   we pursue this course in the context of non - supersymmetric completions, focusing on exotic fermions that carry sm electroweak and twin color charges, as well as on exotic vectors that transform as the bi - fundamental of the electroweak or color groups.   both @xmath2-preserving and @xmath2-breaking mass spectra are considered for the exotic fermions. in the former case   they must be heavier than @xmath3 tev, but can still be sizably produced in the decays of the color bi - fundamental vector. in the @xmath2-breaking scenario,   the exotic fermions can have masses in the few hundred gev range without significantly increasing the fine - tuning.   once pair - produced through the electroweak interactions, they naturally form bound states held together by the twin color force, which subsequently annihilate back to sm particles.   the associated resonance signals are discussed in detail.   we also outline the phenomenology of the electroweak bi - fundamental vectors, some of which mix with the sm @xmath4 and @xmath5 and can therefore be singly produced in hadron collisions.
we investigate light dark matter production associated with a heavy quarkonium at @xmath0 factories in a model - independent way by adopting the effective field theory approach for the interaction of dark matter with standard model particles.   we consider the effective operators for the dark matter - heavy quark interaction, which are relevant to the production of dark matter associated with a heavy quarkonium.   we calculate the cross sections for dark matter production associated with a @xmath1 or @xmath2 to compare with the standard model backgrounds.   we set bounds on the energy scale of new physics for various effective operators and also obtain the corresponding limits for the dark matter - nucleon scattering cross sections for light dark matter with mass of the order of a few gev.
in this paper, properties of a homogeneous bose gas with a feshbach resonance are studied in the dilute region at zero temperature.   the stationary state contains condensations of atoms and molecules.   the ratio of the molecule density to the atom density is @xmath0.   there are two types of excitations, molecular excitations and atomic excitations.   atomic excitations are gapless, consistent with the traditional theory of a dilute bose gas.   the molecular excitation energy is finite in the long wavelength limit as observed in recent experiments on @xmath1rb.   in addition, the decay process of the condensate is studied.   the coefficient of the three - body recombination rate is about 140 times larger than that of a bose gas without a feshbach resonance, in reasonably good agreement with the experiment on @xmath2na.
as the first step in a comprehensive, comparative, direct analysis of the spectra of type  ia supernovae ( sne  ia ), we use the parameterized supernova synthetic  spectrum code, * synow *, to interpret 26 spectra of the well  observed sn  1994d.   our results are consistent with the traditional view that the composition structure ( element abundance fractions versus ejection velocity ) is radially stratified.   we find that resonance   scattering features due to permitted lines of ca  ii, na  i, and fe  ii persist to more than 100 days after explosion. the fitting parameters for sn  1994d, together with those to be determined for other sne  ia, will provide an internally consistent quantification of the spectroscopic diversity among sne  ia, and shed light on how the various manifestations of observational diversity are related to their physical causes.
cosmic acceleration is explained quantitatively, as an apparent effect due to gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe.   `` dark energy '' is a misidentification of those aspects of gravitational energy which by virtue of the equivalence principle can not be localised, namely gradients in the energy due to the expansion of space and spatial curvature variations in an inhomogeneous universe.   a new scheme for cosmological averaging is proposed which solves the sandage  de vaucouleurs paradox.   concordance parameters fit supernovae luminosity distances, the angular scale of the sound horizon in the cmb anisotropies, and the effective comoving baryon acoustic oscillation scale seen in galaxy clustering statistics.   key observational anomalies are potentially resolved, and unique predictions made, including a quantifiable variance in the hubble flow below the scale of apparent homogeneity.   = cmr5=cmr7 # 1 _    # 1|#1    # 1 # 1#2#3#1#3#1#2 # 1#2#1#1#2    # 1 _ # 1 _ # 1#2    # 1astrophys.   j.  * # 1 * # 1phys.   lett.  *   # 1 * # 1class.   quantum grav.  * # 1 * # 1gen.   relativ.   grav.  *   # 1 *    march 2007.   an essay which received _ honorable mention _ in the 2007 gravity research foundation essay competition.
we study the properties and the molecular content of the host of a type - ia supernova ( sn1997ey ).   this @xmath0 host is the brightest submillimetre source of the sample of type - ia supernova hosts observed at 450@xmath1 m and 850@xmath1 m by @xcite.   observations were performed at iram-30 m to search for co(2 - 1 ) and co(3 - 2 ) lines in good weather conditions but no signal was detected.   the star formation rate can not exceed 50 @xmath2/yr.   these negative results are confronted with an optical analysis of a keck spectrum and other data archives.   we reach the conclusion that this galaxy is a late - type system ( 0.7  @xmath3 ), with a small residual star - formation activity ( 0.2  m@xmath4yr@xmath5 ) detected in the optical.   no source of heating ( agn or starburst ) is found to explain the submillimetre - continuum flux and the non - co detection excludes the presence of a large amount of cold gas.   we thus suggest that either the star formation activity is hidden in the nucleus ( with @xmath6 ) or this galaxy is passive or anemic and this flux might be associated with a background galaxy.       supernovae : individual : sn1997ey  radio lines : galaxies  submillimetre  galaxies : general  methods : observational
we calculate high - order quasinormal modes with large imaginary frequencies for electromagnetic and gravitational perturbations in nearly extremal schwarzschild - de sitter spacetimes.   our results show that for low - order quasinormal modes, the analytical approximation formula in the extremal limit derived by cardoso and lemos is a quite good approximation for the quasinormal frequencies as long as the model parameter @xmath0 is small enough, where @xmath1 and @xmath2 are the black hole horizon radius and the surface gravity, respectively. for high - order quasinormal modes,   to which corresponds quasinormal frequencies with large imaginary parts, on the other hand, this formula becomes inaccurate even for small values of @xmath0.   we also find that the real parts of the quasinormal frequencies have oscillating behaviors in the limit of highly damped modes, which are similar to those observed in the case of a reissner - nordstr " om black hole.   the amplitude of oscillating @xmath3 as a function of @xmath4 approaches a non - zero constant value for gravitational perturbations and zero for electromagnetic perturbations in the limit of highly damped modes, where @xmath5 denotes the quasinormal frequency.   this means that for gravitational perturbations, the real part of quasinormal modes of the nearly extremal schwarzschild - de sitter spacetime appears not to approach any constant value in the limit of highly damped modes. on the other hand, for electromagnetic perturbations,   the real part of frequency seems to go to zero in the limit.
the process of lepton pair production in antiproton - proton collisions at panda experiment is simulated for studying the distributions of energy, transverse momentum and angle variables of individual leptons created in a antiquark - quark annihilation subprocess @xmath0.   the correlations between mentioned above physical variables and the corresponding distributions of the number of events versus the values of these variables are presented.   a special attention is paid to the distributions that describe the produced @xmath1-system as a whole system.   it is shown that the spectrum of the total energy of @xmath1 pair may spread from 1 gev up to 12 gev and in about a half of events its energy is higher than 5 gev, i.e. the produced pairs are rather energetic.   it is argued that the measurement of the total transverse momentum of a lepton pair as a whole may provide an important information about an intrinsic transverse momentum @xmath2 that appear due to the fermi motion of quarks inside the nucleon.   the problems due to the presence of fake leptons that appear from meson decays are discussed also.   it is shown that in muon pair production case about of @xmath3 of events may not contain charged pions at all in their final state, i.e. they would be free of fake muons. in the remaining part of events, the information about the muon production vertex and the moderate @xmath4-cuts from below may be also useful for discrimination of fake muons.   the contribution from the background processes that may contain leptons is discussed also.
we study an effect of inhomogeneity of density distribution of the universe.   we propose a new lagrangian perturbation theory with a backreaction effect by inhomogeneity.   the inhomogeneity affects the expansion rate in a local domain and its own growing rate.   we numerically analyze a one - dimensional plane - symmetric model, and calculate the probability distribution functions ( pdfs ) of several observed variables to discuss those statistical properties.   we find that the pdf of pairwise peculiar velocity shows an effective difference from the conventional lagrangian approach, i.e. even in one - dimensional plane symmetric case, the pdf approaches an exponential form in a small relative - velocity region, which agree with the n - body simulation.   -0.5 in 16.5 cm 8.75 in 0.5 in
it is well known experimentally that well - quenched amorphous solids exhibit a plastic instability in the form of a catastrophic shear localization at a well defined value of the external strain.   the instability may develop to a shear - band that in some cases is followed by a fracture.   it is also known that the values of the yield - strain ( and yield - stress ), as well as the direction of the shear band with respect to the principal stress axis, vary considerably with variations in the external loading conditions. in this paper   we present a microscopic theory of these phenomena for 2-dimensional athermal amorphous solids that are strained quasi - statically.   we present analytic formulae for the yield - strains for different loading conditions, and well as for the angles of the shear bands.   we explain that the external loading conditions determine the eigenvalues of the quadrupolar eshelby inclusions which model the non - affine displacement field.   these inclusions model elementary plastic events and determine both the yield - strain and the direction of the shear - band.   we show that the angles of the shear bands with respect to the principal stress axis are limited theoretically between @xmath0 and @xmath1.   available experimental data conform to this prediction.
we consider a hypothetical substance, where interaction between ( within ) structural elements of condensed matter ( molecules, nanoparticles, clusters, layers, wires etc. )   depends on state of cooper pairs : an additional work must be made against this interaction to break a pair.   such a system can be described by bcs hamiltonian with the external pair potential term. in this model   the potential essentially renormalizes the order parameter : if the pairing lowers energy of the structure the energy gap is slightly enlarged at zero temperature and asymptotically tends to zero as temperature rises.   thus the critical temperature of such a superconductor is equal to infinity formally. for this case   the effective ginzburg - landau theory is formulated, where the coherence length decreases as temperature rises, the gl parameter and the second critical field are increasing functions of temperature unlike the standard theory. if the pairing enlarges energy of the structure then suppression of superconductivity and the first order phase transition occur.
we consider new regular exact spherically symmetric solutions of a nonminimal einstein  yang - mills theory with a cosmological constant and a gauge field of magnetic wu - yang type.   the most interesting solutions found are black holes with metric and curvature invariants that are regular everywhere, i.e., regular black holes.   we set up a classification of the solutions according to the number and type of horizons.   the structure of these regular black holes is characterized by four specific features : a small cavity in the neighborhood of the center, a repulsion barrier off the small cavity, a distant equilibrium point, in which the metric function has a minimum, and a region of newtonian attraction.   depending on the sign and value of the cosmological constant the solutions are asymptotically de sitter ( ds ), asymptotically flat, or asymptotically anti - de sitter ( ads ).
we have conducted a spectroscopic survey of the inner regions of the sagittarius ( sgr ) dwarf galaxy using the aaomega spectrograph on the anglo - australian telescope.   we determine radial velocities for over 1800 sgr star members in 6 fields that cover an area 18.84 deg@xmath0, with a typical accuracy of @xmath1.   motivated by recent numerical models of the sgr tidal stream that predict a substantial amount of rotation in the dwarf remnant core, we compare the kinematic data against n - body models that simulate the stream progenitor as ( i ) a pressure - supported, mass - follows - light system, and ( ii ) a late - type, rotating disc galaxy embedded in an extended dark matter halo.   we find that the models with little, or no intrinsic rotation clearly yield a better match to the mean line - of - sight velocity in all surveyed fields, but fail to reproduce the shape of the line - of - sight velocity distribution.   this result rules out models wherein the prominent bifurcation observed in the leading tail of the sgr stream was caused by a transfer from intrinsic angular momentum from the progenitor satellite into the tidal stream.   it also implies that the trajectory of the young tidal tails has not been affected by internal rotation in the progenitor system.   our finding indicates that new, more elaborate dynamical models, in which the dark and luminous components are treated independently, are necessary for _ simultaneously _ reproducing both the internal kinematics of the sgr dwarf and the available data for the associated tidal stream.
we review a recent proposal for the construction of a quantum theory of the gravitational field. the proposal is based on approximating the continuum theory by a discrete theory that has several attractive properties, among them, the fact that in its canonical formulation it is free of constraints.   this allows to bypass many of the hard conceptual problems of traditional canonical quantum gravity. in particular   the resulting theory implies a fundamental mechanism for decoherence and bypasses the black hole information paradox.
the existence of stable magnetic configurations in white dwarfs, neutron stars and various non - convective stellar regions is now well recognized.   it has recently been shown numerically that various families of equilibria, including axisymmetric mixed poloidal - toroidal configurations, are stable. here   we test the stability of an analytically - derived non force - free magnetic equilibrium, using three - dimensional magnetohydrodynamic simulations : the mixed configuration is compared with the dynamical evolution of its purely poloidal and purely toroidal components, both known to be unstable.   the mixed equilibrium shows no sign of instability under white noise perturbations.   this configuration therefore provides a good description of magnetic equilibrium topology inside non - convective stellar objects and will be useful to initialize magneto - rotational transport in stellar evolution codes.
the rayleigh - taylor instability of a magnetic fluid superimposed on a non - magnetic liquid of lower density may be suppressed with the help of a spatially homogeneous magnetic field rotating in the plane of the undisturbed interface.   starting from the complete set of navier - stokes equations for both liquids a floquet analysis is performed which consistently takes into account the viscosities of the fluids.   using experimentally relevant values of the parameters we suggest to use this stabilization mechanism to provide controlled initial conditions for an experimental investigation of the rayleigh - taylor instability.
the dependence of the nuclear force on standard model parameters plays an important role in bounding time and space variations of fundamental couplings over cosmological time scales.   we discuss the quark - mass dependence of deuteron and di - neutron binding in a systematic chiral expansion.   the leading quark - mass dependence of the nuclear force arises from one - pion exchange and from local quark - mass dependent four - nucleon operators with coefficients that are presently unknown. by varying these coefficients while leaving nuclear observables at the physical values of the quark masses invariant, we find scenarios where two - nucleon physics depends both weakly and strongly on the quark masses. while the determination of these coefficients is an exciting future opportunity for lattice   qcd, we conclude that, at present, bounds on time and space variations of fundamental parameters from the two - nucleon sector are much weaker than previously claimed.   this brings into question the reliability of coupling - constant bounds derived from more complex nuclei and nuclear processes.   * variation of fundamental couplings + and nuclear forces *    * silas r.  beane and martin j.  savage *
based on a simple model for spin - polarized scanning tunneling spectroscopy ( sp - sts ) we study how tip magnetization and electronic structure affects the differential conductance ( @xmath0 ) tunneling spectrum of an fe(001 ) surface.   we take into account energy dependence of the vacuum decay of electron states, and tip electronic structure either using an ideal model or based on ab initio electronic structure calculation. in the sts approach,   topographic and magnetic contributions to @xmath0 can clearly be distinguished and analyzed separately.   our results suggest that the sensitivity of sts on a magnetic sample can be tuned and even enhanced by choosing the appropriate magnetic tip and bias set point, and the effect is governed by the effective spin - polarization.
we investigate lipatov s qcd effective action for the qcd high energy limit and propose a pole prescription for higher order induced vertices.   the latter can be used in the evaluation of loop corrections to high energy factorized matrix elements within the effective action approach.   the proposed prescription respects the symmetry properties of the unregulated vertices.   explicit results are presented up to third order in the gauge coupling, while an iterative procedure for higher orders is proposed.   ift - uam / csic-11 - 105 + lpn11 - 95
a broadcast network is a classical network with all source messages collocated at a single source node. for broadcast networks,   the standard cut - set bounds, which are known to be loose in general, are closely related to union as a specific set operation to combine the basic cuts of the network.   this paper provides a new set of network coding bounds for general broadcast networks.   these bounds combine the basic cuts of the network via a variety of set operations ( not just the union ) and are established via only the submodularity of shannon entropy.   the tightness of these bounds are demonstrated via applications to combination networks.
we have analyzed the intra - group light component of 3 hickson compact groups ( hcg 79, hcg 88 and hcg 95 ) with detections in two of them : hcg 79, with @xmath0 of the total @xmath1 band luminosity and hcg 95 with @xmath2.   hcg 88 had no component detected.   this component is presumably due to tidally stripped stellar material trapped in the group potential and represents an efficient tool to determine the stage of dynamical evolution and to map its gravitational potential. to detect this low surface brightness structure   we have applied the wavelet technique ov_wav, which separates the different components of the image according to their spatial characteristic sizes.
pair production processes of neutral higgs particles will allow us to study the trilinear higgs couplings at future high  energy colliders.   several mechanisms give rise to multi   higgs final states in hadron interactions. in the present paper   we investigate higgs pair production in gluon  gluon collisions.   after recapitulating pair production in the standard model, the analysis of the cross sections is carried out in detail for the neutral higgs particles in the minimal supersymmetric extension.   @=11    citexr#2@fileswauxout citeaciteforciteb:=#2#1   @=12        # 1    0.26 cm 0.26 cm    desy 95215 + december 1995 + hep - ph/9603205    pair production of neutral higgs particles + in gluon  gluon collisions    t.  plehn@xmath0, m.  spira@xmath1 and p.  m.  zerwas@xmath0 +    @xmath0 deutsches elektronen  synchrotron desy, d22603 hamburg, frg +    @xmath2 ii.   institut fr theoretische physik, d22761 hamburg, frg +
much insight into the low temperature properties of quantum magnets has been gained by generalizing them to symmetry groups of order @xmath0, and then studying the large @xmath0 limit. in this paper   we consider an unusual aspect of their finite temperature behavior  their exhibiting a phase transition between a perfectly paramagetic state and a paramagnetic state with a finite correlation length at @xmath1.   we analyze this phenomenon in some detail in the large `` spin '' ( classical ) limit of the su@xmath2 ferromagnet which is also a lattice discretization of the cp@xmath3 model.   we show that at @xmath1 the order of the transition is governed by lattice connectivity. at finite values of @xmath0,   the transition goes away in one or less dimension but survives on many lattices in two dimensions and higher, for sufficiently large n. the latter conclusion contradicts a recent conjecture of sokal and starinets @xcite, yet is consistent with the known finite temperature behavior of the su@xmath4 case.   we also report closely related first order paramagnet - ferromagnet transitions at large @xmath0 and shed light on a violation of elitzur s theorem at infinite @xmath0 via the large @xmath5 limit of the @xmath5 state potts model, reformulated as an ising gauge theory.  ,    @xmath6 expansion, quantum magnetism, nonlinear @xmath7 model, cp@xmath8 model, phase transitions
i first outline new results on the angular modulation of wimp dark matter scattering on targets in terrestrial laboratories, based on our uncertainties of the wimp halo distribution, i then outline an exciting new result which indicates that for the high end of allowed susy wimp scattering cross sections there exists a new distribution of wimp dark matter in our solar system which could produce a dramatically different signal from halo wimp dark matter in terrestrial detectors.
the heating of the sun s chromosphere remains poorly understood.   while progress has been made on understanding what drives the quiet sun internetwork chromosphere, chromospheric heating in strong magnetic field regions continues to present a difficult challenge, mostly because of a lack of observational constraints.   we use high - resolution spectropolarimetric data from the swedish 1-m solar telescope to identify the location and spatio - temporal properties of heating in the magnetic chromosphere.   in particular, we report the existence of raised - core spectral line profiles in the  @xmath0 line.   these profiles are characterized by the absence of an absorption line core, showing a quasi - flat profile between @xmath1  , and are abundant close to magnetic bright - points and plage.   comparison with 3d mhd simulations indicates that such profiles occur when the line - of - sight goes through an `` elevated temperature canopy '' associated with the expansion with height of the magnetic field of flux concentrations.   this temperature canopy in the simulations is caused by ohmic dissipation where there are strong magnetic field gradients.   the raised - core profiles are thus indicators of locations of increased chromospheric heating.   we characterize the location and temporal and spatial properties of such profiles in our observations, thus providing much stricter constraints on theoretical models of chromospheric heating mechanisms than before.
the geometrically frustrated spin-1/2 ising - heisenberg model on triangulated husimi lattices is exactly solved by combining the generalized star - triangle transformation with the method of exact recursion relations.   the ground - state and finite - temperature phase diagrams are rigorously calculated along with both sublattice magnetizations of the ising and heisenberg spins.   it is evidenced that the ising - heisenberg model on triangulated husimi lattices with two or three inter - connected triangles - in - triangles units displays in a highly frustrated region a quantum disorder irrespective of temperature, whereas the same model on triangulated husimi lattices with a greater connectivity of triangles - in - triangles units exhibits at low enough temperatures an outstanding quantum order due to the order - by - disorder mechanism.   the quantum reduction of both sublattice magnetizations in the peculiar quantum ordered state gradually diminishes with increasing the coordination number of underlying husimi lattice.
we have surveyed two large samples of nearby low - luminosity agn with the vla to search for flat - spectrum radio cores, similar to sgr a * in the galactic center.   roughly one third of all galaxies are detected ( roughly one half if hii transition objects are excluded from the sample ), many of which have compact radio cores.   follow - up observations with the vlba have confirmed that these cores are non - thermal in origin, with brightness temperatures of @xmath0 k. the brightest of these are resolved into linear structures.   the radio spectral indices of the cores are quite flat ( @xmath1 ), with no evidence for the highly inverted radio cores predicted in the adaf model.   spectrum and morphology of the compact radio emission is typical for radio jets seen also in more luminous agn.   the emission - line luminosity seems to be correlated with the radio core flux. together with the vlbi observations this suggests that optical and radio emission in at least half the low - luminosity seyferts and liners are black hole powered.   we find only a weak correlation between bulge luminosity and radio flux and an apparently different efficiency between elliptical and spiral galaxies for producing radio emission at a given optical luminosity.
this paper investigates the optimum source transmission strategy to maximize the capacity of a multiple - input single - output ( miso ) amplify - and - forward relay channel, assuming source - relay channel mean feedback at the source.   the challenge here is that relaying introduces a nonconvex structure in the objective function, thereby excluding the possible use of previous methods dealing with mean feedback that generally rely on the concavity of the objective function.   a novel method is employed, which divides the feasible set into two subsets and establishes the optimum from one of them by comparison. as such  , the optimization is transformed into the comparison of two nonnegative random variables in the _ laplace transform order _, which is one of the important stochastic orders.   it turns out that the optimum transmission strategy is to transmit along the known channel mean and its orthogonal eigenchannels.   the condition for rank - one precoding ( beamforming ) to achieve capacity is also determined.   our results subsume those for traditional miso precoding with mean feedback.
directional detection of wimps, in which the energies and directions of the recoiling nuclei are measured, currently presents the only prospect for probing the local _ velocity _ distribution of galactic dark matter.   we investigate the extent to which future directional detectors would be capable of probing dark matter substructure in the form of streams.   we analyse the signal expected from a sagittarius - like stream and also explore the full parameter space of stream speed, direction, dispersion and density. using a combination of non - parametric directional statistics, a profile likelihood ratio test and bayesian parameter inference we find that within acceptable exposure times ( @xmath0 kg yr for cross sections just below the current exclusion limits ) future directional detectors will be sensitive to a wide range of stream velocities and densities.   we also examine and discuss the importance of the energy window of the detector.
the ideals of the eighteenth century s age of enlightenment are the foundation of modern democracies.   the era was characterized by thinkers who promoted progressive social reforms that opposed the long - established aristocracies and monarchies of the time.   prominent examples of such reforms include the establishment of inalienable human rights, self - governing republics, and market capitalism.   twenty - first century democratic nations can benefit from revisiting the systems developed during the enlightenment and reframing them within the techno - social context of the information age.   this article explores the application of social algorithms that make use of thomas paine s ( english : 17371809 ) representatives, adam smith s ( scottish : 17231790 ) self - interested actors, and marquis de condorcet s ( french : 17431794 ) optimal decision making groups.   it is posited that technology - enabled social algorithms can better realize the ideals articulated during the enlightenment.   = 1    collective decision making, computational governance, e - participation, e - democracy, computational social choice theory.
we describe a surface structure consisting of a metal - air interface where the metallic part consists of two metallic segments with a periodic modulation of the interface between them.   such a structure possesses a different transmissivity for a surface plasmon polariton incident on it from one side of it than it has for a surface plasmon polariton incident on it from the opposite side.   this asymmetric transmission of a surface plasmon polariton is based on the suppression of the zero - order bragg beam which, for a certain value of the modulation depth, is not transmitted through the structure, while the diffraction efficiencies of the + 1 and -1 bragg beams can be modified by varying the period of grating and/or the angle of incidence. for a certain range of the incidence angle   one can observe asymmetry in transmittance for the -1 mode while the + 1 mode is completely suppressed.   by varying the material and geometrical parameters of the diffractive structure one can control the contrast transmission that characterizes the degree of the asymmetry.   this property of the structure is demonstrated by the results of computer simulation calculations.
a quantum - mechanical gaussian wave - packet approach to the theoretical description of nuclear motions in a condensed - phase environment is developed.   general expressions for the time - dependent reduced density matrix are given for a harmonic potential surface, and the exact quantum dynamics is found for a microscopic system - plus - bath model.   particular attention is devoted to the influence of initial correlations between system and bath for the outcome of a pump - probe experiment.   we show that the standard factorized preparation, compared to a more realistic correlated preparation, leads to significantly different stimulated emission spectra at high temperatures.   recent experiments for the reaction center are analyzed using this formalism.
recent theoretical work has pointed out that the transition layer between a jet an the medium surrounding it may be more complex than previously thought. under physically realizable conditions, the transverse profile of the lorentz factor in the boundary layer can be non - monotonic, displaying the absolute maximum where the flow is faster than at the jet spine, followed by an steep fall off.   likewise, the rest - mass density, reaches an absolute minimum ( coincident with the maximum in lorentz factor ) and then grows until it reaches the external medium value.   such a behaviour is in contrast to the standard monotonic decline of the lorentz factor ( from a maximum value at the jet central spine ) and the corresponding increase of the rest - mass density ( from the minimum reached at the jet core ).   we study the emission properties of the aforementioned anomalous shear layer structures in kiloparsec - scale jets aiming to show observable differences with respect to conventional monotonic and smooth boundary layers.
in the asymptotic theory of quantum hypothesis testing, the minimal error probability of the first kind jumps sharply from zero to one when the error exponent of the second kind passes by the point of the relative entropy of the two states in an increasing way.   this is well known as the direct part and strong converse of quantum stein s lemma.    here   we look into the behavior of this sudden change and have make it clear how the error of first kind grows smoothly according to a lower order of the error exponent of the second kind, and hence we obtain the second - order asymptotics for quantum hypothesis testing.   this actually implies quantum stein s lemma as a special case.   meanwhile, our analysis also yields tight bounds for the case of finite sample size.   these results have potential applications in quantum information theory.   our method is elementary, based on basic linear algebra and probability theory.   it deals with the achievability part and the optimality part in a unified fashion.
recent developments on the four dimensional ( 4d ) lattice studies of the finite temperature electroweak phase transition ( ewpt ) are summarized.   the phase diagram is given in the continuum limit.   the finite temperature su(2)-higgs phase transition is of first order for higgs - boson masses @xmath0 gev. above this endpoint   only a rapid cross - over can be seen.   the full 4d result agrees completely with that of the dimensional reduction approximation.   the higgs - boson endpoint mass in the standard model ( sm ) would be @xmath1 gev.   taking into account the lep higgs - boson mass lower bound excludes any ewpt in the sm.   a one - loop calculation of the static potential in the su(2)-higgs model enables a precise comparison between lattice simulations and perturbative results.   the most popular extension of the sm, the minimal supersymmetric sm ( mssm ) is also studied on 4d lattices.
the casimir force is calculated between au thin films that are described by a drude model with a frequency dependent damping function.   the model parameters are obtained from available experimental data for au thin films.   two cases are considered ; annealed and nonannealed films that have a different damping function.   compared with the calculations using a drude model with a constant damping parameter, we observe changes in the casimir force of a few percent.   this behavior is only observed in films of no more than 300 @xmath0 thick.
the use of wide - field multi - object fiber - input spectrographs for large redshift surveys introduces the possibility of variations in the observed signal - to - noise ratio across the survey area due to errors in positioning the fibers with respect to the target image positions, leading to position - dependent errors in the survey catalog.   this paper brings together a comprehensive description of the sources of fiber - to - image position errors in different instrument designs, and quantifies their effects on the efficiency with which signal is recorded. for point sources, a function relating a fractional efficiency and an equivalent aperture correction to the fiber - to - image position error,   the fiber diameter and the image size is plotted for typical values of fiber and image sizes found in current instruments.   the tools required by observers to maximize the efficiency of fiber - spectrographic surveys are discussed.
the performance of the gluex forward calorimeter was studied using a small version of the detector and a variable energy electron beam derived from the hall b tagger at jefferson lab. for electron energies from 110 mev to 260 mev, which are near the lower - limits of the design sensitivity,   the fractional energy resolution was measured to range from @xmath0 to @xmath1, which meets the design goals.   the use of custom 250  mhz flash adcs for readout allowed precise measurements of signal arrival times.   the detector achieved timing resolutions of @xmath2 ns for a single @xmath3  mv pulse, which will allow timing discrimination of photon beam bunches and out - of - time background during the operation of the gluex detector.   gluex, jefferson lab, calorimetry, lead glass, flash adc
a universal quantum simulator would enable efficient simulation of quantum dynamics by implementing quantum - simulation algorithms on a quantum computer.   specifically the quantum simulator would efficiently generate qubit - string states that closely approximate physical states obtained from a broad class of dynamical evolutions.   i provide an overview of theoretical research into universal quantum simulators and the strategies for minimizing computational space and time costs.   applications to simulating many - body quantum simulation and solving linear equations are discussed    computing, quantum algorithms, quantum simulation
in the present article we have obtained new set of exact solutions of einstein field equations for anisotropic fluid spheres by using the herrera et al.  @xcite algorithm.   the anisotropic fluid solutions so obtained join continuously to schwarzschild exterior solution across the pressure free boundary.it is observed that most of the new anisotropic solutions are well behaved and utilized to construct the super - dense star models such as neutron star and pulsars.   * keywords : * anisotropic fluids ; anisotropic factor ; einstein s equations ; schwarzschild solution ; neutron star ; pulsars.
we consider methods to identify the classical ground state for an exchange - coupled heisenberg antiferromagnet on a non - bravais lattice with interactions @xmath0 to several neighbor distances. here   we apply this to the unusual `` octahedral '' lattice in which spins sit on the edge midpoints of a simple cubic lattice.   our approach is informed by the eigenvectors of @xmath0 with largest eigenvalues.   we discovered two families of non - coplanar states : ( i ) two kinds of commensurate state with cubic symmetry, each having twelve sublattices with spins pointing in ( 1,1,0 ) directions in spin space ( modulo a global rotation ) ; ( ii ) varieties of incommensurate conic spiral.   the latter family is addressed by projecting the three - dimensional lattice to a one - dimensional chain, with a basis of two ( or more ) sites per unit cell.   # 1    *s *
we discuss the high - temperature superconductivity in copper oxide ceramics.   we propose an effective hamiltonian to describe the dynamics of electrons or holes injected into the copper oxide layers.   we show that our approach is able to account for both the pseudogap and the superconductivity gap. for the hole - doped cuprates we discuss in details the underdoped, optimal doped, and overdoped regions of the phase diagram. in the underdoped region   we determine the doping dependence of the upper critical magnetic field, the vortex region, and the discrete states bounded to the core of isolated vortices.   we explain the origin of the fermi arcs and fermi pockets.   moreover, we discuss the recently reported peculiar dependence of the specific heat on the applied magnetic field. we determine the critical doping where the pseudogap vanishes.   we find that in the overdoped region the superconducting transition is described by the conventional d - wave bcs theory.   we discuss the optimal doping region and the crossover between the underdoped region and the overdoped region.   we also discuss briefly the electron - doped cuprate superconductors.
we demonstrate how the fundamental manifold ( fm ) can be used to cross - calibrate distance estimators even when those  standard candles " are not found in the same galaxy.   such an approach greatly increases the number of distance measurements that can be utilized to check for systematic distance errors and the types of estimators that can be compared.   here we compare distances obtained using sn ia, cepheids, surface brightness fluctuations, the luminosity of the tip of the red giant branch, circumnuclear masers, eclipsing binaries, rr lyrae stars, and the planetary nebulae luminosity functions.   we find no significant discrepancies ( differences are @xmath0 ) between distance methods, although differences at the @xmath1 10% level can not yet be ruled out.   the potential exists for significant refinement because the data used here are heterogeneous b - band magnitudes that will soon be supplanted by homogeneous, near - ir magnitudes.   we illustrate the use of fm distances to 1 ) revisit the question of the metallicity sensitivity of various estimators, confirming the dependence of sn ia distances on host galaxy metallicity, and 2 ) provide an alternative calibration of h@xmath2 that replaces the classical ladder approach in the use of extragalactic distance estimators with one that utilizes data over a wide range of distances simultaneously.
in a recent preprint ( cond - mat/9803170 ), van  langen, knops, paasschens and beenakker attempt to re - analyze the proposal of loss, schoeller and goldbart ( lsg ) [ phys.   rev.   b  * 48 *, 15218 ( 1993 ) ] concerning berry phase effects in the magnetoconductance of diffusive systems.   van langen et al.   claim that the adiabatic approximation for the cooperon previously derived by lsg is not valid in the adiabatic regime identified by lsg.   it is shown that the claim of van  langen et al.   is not correct, and that, on the contrary, the magnetoconductance does exhibit the berry phase effect within the lsg regime of adiabaticity.   the conclusion reached by van  langen et al.  is based on a misinterpretation of field - induced dephasing effects, which can mask the berry phase ( and any other phase coherent phenomena ) for certain parameter values.   = 0 epsf.sty
we study entropy production and fluctuation relations in the restricted solid - on - solid growth model, which is a microscopic realization of the kpz equation. solving the one dimensional model exactly on a particular line of the phase diagram   we demonstrate that entropy production quantifies the distance from equilibrium. moreover, as an example of a physically relevant current different from the entropy, we study the symmetry of the large deviation function associated with the interface height. in a special case of a system of length @xmath0   we find that the probability distribution of the variation of height has a symmetric large deviation function, displaying a symmetry different from the gallavotti - cohen symmetry.   # 1#1
we investigate the exact dynamics of trace distance discord by considering two qubits under dephasing whose states belong to a class of @xmath0 states beyond bell diagonal form. the necessary condition for the occurrence of freezing trace distance discord   is found and compared with that of entropic discord.   for an illustration, we consider two interacting qubits coupled to independent reservoirs and demonstrate these dynamical properties of trace distance discord.   it is interesting to find that the freezing trace distance discord exists even for @xmath0 states without maximally mixed marginals and can be tuned by dipole - dipole coupling of two qubits. moreover,   we consider the initial extended werner - like states and investigate the differences between trace distance discord and entanglement.   the influences of initial state and the dipole - dipole coupling of the two qubits on the dynamics of nonclassical correlations are explored.
i utilize the petrov - galerkin formulation and develop a new method for solving the unsteady collisionless boltzmann equation in both the linear and nonlinear regimes. in the first order approximation, the method reduces to a linear eigenvalue problem which is solved using standard numerical methods.   i apply the method to the dynamics of a model stellar disk which is embedded in the field of a soft - centered logarithmic potential.   the outcome is the full spectrum of eigenfrequencies and their conjugate normal modes for prescribed azimuthal wavenumbers.   the results show that the fundamental bar mode is isolated in the frequency space while spiral modes belong to discrete families that bifurcate from the continuous family of van kampen modes. the population of spiral modes in the bifurcating family increases by cooling the disk and declines by increasing the fraction of dark to luminous matter.   it is shown that the variety of unstable modes is controlled by the shape of the dark matter density profile.
we have characterized the typical temporal behaviour of the bright x  ray flares detected from the three supergiant fast x   ray transients showing the most extreme transient behaviour (,, ).   we focus here on the cumulative distributions of the waiting - time ( time interval between two consecutive x  ray flares ), and the duration of the hard x  ray activity ( duration of the brightest phase of an sfxt outburst ), as observed by /ibis in the energy band 1750 kev. adopting the cumulative distribution of waiting - times  , it is possible to identify the typical timescale that clearly separates different outbursts, composed by several single flares at @xmath0ks timescale.   this allowed us to measure the duration of the brightest phase of the outbursts from these three targets, finding that they show heavy - tailed cumulative distributions.   we observe a correlation between the total energy emitted during sfxt outbursts and the time interval covered by the outbursts ( defined as the elapsed time between the first and the last flare belonging to the same outburst as observed by @xmath1 ).   we show that temporal properties of flares and outbursts of the sources, which share common properties regardless different orbital parameters, can be interpreted in the model of magnetized stellar winds with fractal structure from the ob - supergiant stars.       accretion - stars : neutron - x  rays : binaries - x   rays ; individuals :,,
an improved way of taking off - source data for background determination in cherenkov telescope observations is proposed. generalizing the traditional concept of taking on - source / off - source observations of equal duration ( e.g. 30 minutes on followed by 30 minutes off ), _ faster background determination _ ( fbd )   permits an off - source observation with the same zenith angle distribution as the on - source observation to be obtained within less time.   the method permits the on - source observation time to be maximized without compromising the quality of the background determination.   it also increases the signal significance for strong sources.   the only modification necessary in the data acquisition is a small change to the tracking algorithm.   the only modification necessary in the data analysis is to introduce a time normalization which does not increase the systematic errors.   the method could become the normal observing mode for cherenkov telescopes when observing strong sources.
the palatini @xmath0 gravity, is able to probably explain the late time cosmic acceleration without the need for dark energy, is studied. in this paper, we investigate a number of @xmath0 gravity theories in palatini formalism by means of statefinder diagnosis.   we consider two types of @xmath0 theories : ( i ) @xmath1 and ( ii ) @xmath2.   we find that the evolutionary trajectories in the @xmath3 and @xmath4 planes for various types of the palatini @xmath0 theories reveal different evolutionary properties of the universe.   additionally, we use the observational @xmath5 data to constrain models of @xmath0 gravity.
in compressed sensing the matrices that satisfy the restricted isometry property ( rip ) play an important role. but to date, very few results for designing such matrices are available. for applications such as multiplier - less data compression, binary sensing matrices are of interest. the present work constructs deterministic and binary sensing matrices using euler squares. in particular, given a positive integer @xmath0 different from @xmath1 for a prime @xmath2, we show that it is possible to construct a binary sensing matrix of size @xmath3, where @xmath4 is the coherence parameter of the matrix and @xmath5.   the matrices that we construct have small density ( that is, percentage of nonzero entries in the matrix is small ) with no function evaluation in their construction, which support algorithms with low computational complexity. through experimental work,   we show that our binary sensing matrices can be used for such applications as content based image retrieval.   our simulation results demonstrate that the euler square based cs matrices give better performance than their gaussian counterparts.   definition remark example lemma proposition corollary    compressed sensing, coherence, rip, binary sensing matrices, euler squares, cbir.
owing to their isotropy, it is generally believed that ultrahigh energy cosmic rays ( uhecrs ) are extragalactic in origin.   it is then expected that interactions of these cosmic rays with photons of the cosmic background radiation ( cbr ) should produce a drastic reduction in their flux above and energy of about @xmath0 ev ( 50 eev ), the so - called `` gzk effect ''. at present, the existence of this effect is uncertain owing to conflicting observational data and small number statistics.   we show here that a small amount of lorentz invariance violation ( liv ), which could turn off photomeson interactions of uhecrs with the cbr, could explain the uhecr spectrum as measured by _   agasa _ which shows an excess of uhecrs at energies above 100 eev. if new results from the _ auger _ array agree with the _ agasa _ spectrum, this may be interpreted as evidence for a small amount of liv.   if, on the other hand, the new results are consistent with the _ hires _ results favoring a gzk effect, this would place severe constraints on liv and, by implication, on some planck scale quantum gravity models.   we also discuss the power requirements needed to explain the uhecr spectrum for a range of assumptions, including source evolution and liv and show that in all cases our results disfavor a @xmath1-ray burst origin for the uhecrs.   cosmic rays ; lorentz invariance ; quantum gravity ; gamma - ray bursts
microscopic pyramidal pits in a reflective surface, a geometry similar to a retroreflector, are frequently used to enhance signal strength.the enhancement effect is generally attributed to surface plasmons, however, * the sub - wavelength to near - wavelength dimensions of the pyramidal 3d geometry * suggest contributions from diffraction and near - field effects. * our * theoretical analysis of the light intensity distribution * in the similar ( but simpler ) 2d geometry * assuming a perfect conductor screen, that is, in the absence of any plasmon effects, shows that interference patterns forming within the cavity cause a significant * resonant * increase in local intensity.   * such effect can be important for many applications, especially for the widely used raman spectroscopy.   * resonant enhancement * without plasmons * of the emitted raman signal due to enhanced local field amplitude is also possible, which implies that the geometry practically implements a raman laser.   comparison of diffraction patterns obtained with near - field and far - field approaches reveals that the near - field component is responsible for the observed dramatic intensity enhancement, and thus the raman enhancement as well.
this paper considers event - chain monte carlo simulation schemes in order to design an original irreversible markov chain monte carlo ( mcmc ) algorithm for the sampling of complex statistical models.   the functioning principles of mcmc sampling methods are firstly recalled, as well as standard event - chain monte carlo simulation schemes are described. then, a forward event - chain monte carlo sampling methodology is proposed and introduced. this nonreversible mcmc rejection - free simulation algorithm is tested and run for the sampling of high - dimensional ill - conditioned gaussian statistical distributions   numerical experiments demonstrate the efficiency of the proposed approach, compared to standard event - chain and standard monte carlo sampling methods.   accelerations up to several magnitudes are exhibited.    0.3 in
we investigate the dynamics of quantum and classical correlations in a system of two qubits under local colored - noise dephasing channels.   the time evolution of a single qubit interacting with its own environment is described by a memory kernel non - markovian master equation.   the memory effects of the non - markovian reservoirs introduce new features in the dynamics of quantum and classical correlations compared to the white noise markovian case.   depending on the geometry of the initial state the system can exhibit frozen discord and multiple sudden transitions between classical and quantum decoherence [ l. mazzola, j. piilo, s. maniscalco, phys.   rev.   lett.  * 104 *, 200401 ( 2010 ) ].   we provide a geometric interpretation of those phenomena in terms of the distance of the state under investigation to its closest classical state in the hilbert space of the system.    #   1#1 :
the classical model of an oscillator linearly coupled to a string captures, for a low price in technique, many general features of more realistic models for describing a particle interacting with a field or an atom in a electromagnetic cavity.   the scattering matrix and the asymptotic in and out waves on the string can be computed exactly and the phenomenon of resonant scattering can be introduced in the simplest way. the dissipation induced by the coupling of the oscillator to the string can be studied completely. in the case of a dalembert string  , the backreaction leads to an abraham - lorentz - dirac - like equation. in the case of a klein - gordon string  , one can see explicitely how radiation governs the ( meta)stability of the ( quasi)bounded mode.   pacs : 46.40.cd, 46.40.ff, 42.50.ct, 03.65.yz.
a historical problem for indirect exoplanet detection has been contending with the intrinsic variability of the host star.   if the variability is periodic, it can easily mimic various exoplanet signatures, such as radial velocity variations that originate with the stellar surface rather than the presence of a planet. here   we present an update for the hd  99492 planetary system, using new radial velocity and photometric measurements from the transit ephemeris refinement and monitoring survey ( terms ).   our extended time series and subsequent analyses of the ca ii h&k emission lines show that the host star has an activity cycle of @xmath013 years.   the activity cycle correlates with the purported orbital period of the outer planet, the signature of which is thus likely due to the host star activity.   we further include a revised keplerian orbital solution for the remaining planet, along with a new transit ephemeris.   our transit - search observations were inconclusive.
we solve the linearized einstein equations for a specific oscillating mass distribution and discuss the usual counterarguments against the existence of observable gravitational retardations in the `` near zone '', where @xmath0 ( @xmath1 oscillation amplitude of the source, @xmath2 distance from the source ).   we show that they do not apply in the region @xmath3, and prove that gravitational forces are retarded in the immediate vicinity of the source.   an experiment to measure this retardation is proposed, which may provide the first direct experimental observation of propagating gravitational fields.   = - 2.5 cm = -1.5 cm    = 2em    pacs numbers : 04.30.-w, 04.80.nn, 04.80.cc, 04.80.-y
to study the coexistence of two liquid states of water within one simulation box, we implement an equilibrium sedimentation method  which involves applying a gravitational field to the system and measuring / calculating the resulting density profile in equilibrium.   we simulate a system of particles interacting via the st2 potential, a model for water.   we detect the coexistence of two liquid phases at low temperature.
number counts of galaxies in two galex bands ( fuv : 1530 and nuv : 2310, both in ab magnitudes ) are reported.   they provide for the first time in the literature homogeneously calibrated number counts of uv galaxies covering continuously a very wide range of uv magnitude ( 14  23.8 ).   both the fuv and nuv counts are inconsistent with a non - evolution model, while they are in good agreement with evolution models ( essentially luminosity evolution ) derived from the high - z uv luminosity functions of arnouts et al.   ( 2004 ).   it is found that the contribution from galaxies detected by galex to the uv background is 0.68@xmath0 nw m@xmath1 sr@xmath2 at 1530 and 0.99@xmath3 nw m@xmath1 sr@xmath2 at 2310.   these are 66@xmath4% and 44@xmath5% of the total contributions of galaxies to the the uv background at 1530 ( 1.03@xmath3 nw m@xmath1 sr@xmath2 ) and at 2310 ( 2.25@xmath6 nw m@xmath1 sr@xmath2 ), respectively, as estimated using the evolution models.   galaxy counts and star counts in 7 regions, each contains a few deg@xmath7 galex coverage in an area of up to @xmath8 deg@xmath7, are compared with each other to study the region - by - region variance.   this shows that for the galaxy counts the cosmic variance is comparable to the net error due to other uncertainties. the star counts increase with decreasing absolute galactic latitude @xmath9b@xmath9
we fit the volatility fluctuations of the s&p 500 index well by a chi distribution, and the distribution of log - returns by a corresponding superposition of gaussian distributions.   the fourier transform of this is, remarkably, of the tsallis type.   an option pricing formula is derived from the same superposition of black - scholes expressions.   an explicit analytic formula is deduced from a perturbation expansion around a black - scholes formula with the mean volatility.   the expansion has two parts.   the first takes into account the non - gaussian character of the stock - fluctuations and is organized by powers of the excess kurtosis, the second is contract based, and is organized by the moments of moneyness of the option. with this expansion   we show that for the dow jones euro stoxx @xmath0 option data, a @xmath1-hedging strategy is close to being optimal.
we have theoretically investigated 3d focusing of a launched cloud of cold atoms using a pair of magnetic lens pulses ( the alternate - gradient method ).   individual lenses focus radially and defocus axially or vice - versa. the performance of the two possible pulse sequences are compared and found to be ideal for loading both ` pancake'and ` sausage'shaped magnetic / optical microtraps.   it is shown that focusing aberrations are considerably smaller for double - impulse magnetic lenses compared to single - impulse magnetic lenses.   an analysis of the clouds focused by double - impulse technique is presented.
we present an elementary and conceptual proof that the complex exponential map is _ chaotic _ when considered as a dynamical system on the complex plane.   ( this was conjectured by fatou in 1926 and first proved by misiurewicz 55 years later. )   the only background required is a first undergraduate course in complex analysis.
in this paper we study the optimal placement and optimal number of active relay nodes through the traffic density in mobile sensor ad - hoc networks. we consider a setting in which a set of mobile sensor sources is creating data and a set of mobile sensor destinations receiving that data.   we make the assumption that the network is massively dense, _ i.e. _, there are so many sources, destinations, and relay nodes, that it is best to describe the network in terms of macroscopic parameters, such as their spatial density, rather than in terms of microscopic parameters, such as their individual placements.   we focus on a particular physical layer model that is characterized by the following assumptions : i )  the nodes must only transport the data from the sources to the destinations, and do not need to sense the data at the sources, or deliver them at the destinations once the data arrive at their physical locations, and ii ) the nodes have limited bandwidth available to them, but they use it optimally to locally achieve the network capacity.    in this setting, the optimal distribution of nodes induces a traffic density that resembles the electric displacement that will be created if we substitute the sources and destinations with positive and negative charges respectively.   the analogy between the two settings is very tight and have a direct interpretation in wireless sensor networks.
in this paper the stewart - lyth inverse problem is introduced.   it consists of solving two nonlinear differential equations for the first slow - roll parameter and finding the inflaton potential.   the equations are derived from the stewart - lyth equations for the scalar and tensorial perturbations produced during the inflationary period.   the geometry of the phase planes transverse to the trajectories is analyzed, and conclusions about the possible behavior for general solutions are drawn.
the lifshitz - type formulas describing the free energy and the force of the van der waals interaction between an atom ( molecule ) and a single - wall carbon nanotube are obtained.   the single - wall nanotube is considered as a cylindrical sheet carrying a two - dimensional free electron gas with appropriate boundary conditions on the electromagnetic field.   the obtained formulas are used to calculate the van der waals free energy and force between a hydrogen atom ( molecule ) and single - wall carbon nanotubes of different radia.   comparison studies of the van der waals interaction of hydrogen atoms with single- and multi - wall carbon nanotubes show that depending on atom - nanotube separation distance the idealization of graphite dielectric permittivity is already applicable to nanotubes with only two or three walls.
electron dynamics in crystalline semiconductors is described by distinguishing between an instantaneous velocity related to electron s momentum and an average velocity related to its quasi - momentum in a periodic potential.   it is shown that the electron velocity used in the theory of electron transport and free - carrier optics is the average electron velocity, not the instantaneous velocity.   an effective mass of charge carriers in solids is considered and it is demonstrated that, in contrast to the `` acceleration '' mass introduced in textbooks, it is a `` velocity '' mass relating carrier velocity to its quasi - momentum that is a much more useful physical quantity. among other advantages, the velocity mass is a scalar for spherical but nonparabolic energy bands  @xmath0, whereas the acceleration mass is not a scalar.   important applications of the velocity mass are indicated.   a two - band  @xmath1 model is introduced as the simplest example of a band structure that still keeps track of the periodic lattice potential.   it is remarked that the two - band model, adequately describing narrow - gap semiconductors ( including zero - gap graphene ), strongly resembles the special theory of relativity.   instructive examples of the `` semi - relativistic '' analogy are given.   the presentation has both scientific and pedagogical aspects.
we have proposed a new minimal extension of the standard model with a heavy majorana fermion triplet(@xmath0 ) and an extra scalar doublet(@xmath1 ) so that the seesaw mechanism is radiative and can be accessible at upcoming accelerators.   the origin of neutrino mass via the famous seesaw mechanism through the heavy majorana fermion triplet has been discussed.   we have proposed a mechanism of leptogenesis by the decay of the lightest neutral component of the fermion triplet into a standard model lepton doublet and an extra higgs doublet.   the important thing is that the leptogenesis scenario discussed in this letter can be of tev scale and hence can be testable at large hadron collider(lhc ).   we have also discussed a possible dark matter scenario in our model and the possible phenomenology of the fermion field @xmath0.
the earth s density distribution can be approximately considered piecewise continuous at the scale of two - flavor oscillations of neutrinos with energies about 1  mev.   this quite general presumption appears to be enough to analytically calculate the day - night asymmetry factor. using the explicit time avergaing procedure,   we show that, within the leading - order approximation, this factor is determined by the electron density immediately before the detector, i.e. in the earth s crust. within the approximation chosen,   the resulting asymmetry factor does not depend either on the properties of the inner earth s layers or on the substance and the dimensions of the detector. for beryllium neutrinos  , we arrive at the asymmetry factor estimation of about @xmath0, which is at least one order of magnitude beyond the present experimental resolution, including that of the borexino experiment.
in a recent letter ( apj 517, l155 ) lenz et al.   have shown the evidence of uniform temperature along steady long coronal loops observed by trace in two different passbands ( 171    and 195    filters ).   we propose that such an evidence can be explained by the sub - arcsecond structuring of the loops across the magnetic field lines. in this perspective, we present a model of a bundle of six thin parallel hydrostatic filaments with temperature stratification dictated by detailed energy balance and with temperatures at their apex ranging between 0.8 and 5 mk. if analyzed as a single loop, the bundle would appear isothermal along most of its length.
a linear boltzmann transport model within perturbative qcd is developed for the study of parton propagation inside the quark - gluon plasma.   both leading partons and thermal recoil partons are tracked so that one can also study jet - induced medium excitations. in this study  , we implement the complete set of elastic parton scattering processes and investigate elastic parton energy loss, transverse momentum broadening and their nontrivial energy and length dependence.   we further investigate medium modifications of the jet shape and fragmentation functions of reconstructed jets.   contributions from thermal recoil partons are found to have significant influences on jet shape, fragmentation functions and angular distribution of reconstructed jets.
this paper presents the development of a new continuous forest fire model implemented as a weighted local small - world network approach.   this new approach was designed to simulate fire patterns in real, heterogeneous landscapes.   the wildland fire spread is simulated on a square lattice in which each cell represents an area of the land s surface.   the interaction between burning and non - burning cells, in the present work induced by flame radiation, may be extended well beyond nearest neighbors.   it depends on local conditions of topography and vegetation types.   an approach based on a solid flame model is used to predict the radiative heat flux from the flame generated by the burning of each site towards its neighbors.   the weighting procedure takes into account the self - degradation of the tree and the ignition processes of a combustible cell through time.   the model is tested on a field presenting a range of slopes and with data collected from a real wildfire scenario.   the critical behavior of the spreading process is investigated.
how does information flow in online social networks?   how does the structure and size of the information cascade evolve in time? how can we efficiently mine the information contained in cascade dynamics?   we approach these questions empirically and present an efficient and scalable mathematical framework for quantitative analysis of cascades on networks.   we define a _ cascade generating function _ that captures the details of the microscopic dynamics of the cascades.   we show that this function can also be used to compute the macroscopic properties of cascades, such as their size, spread, diameter, number of paths, and average path length.   we present an algorithm to efficiently compute cascade generating function and demonstrate that while significantly compressing information within a cascade, it nevertheless allows us to accurately reconstruct its structure.   we use this framework to study information dynamics on the social network of digg.   digg allows users to post and vote on stories, and easily see the stories that friends have voted on. as a story spreads on digg through voting, it generates cascades.   we extract cascades of more than 3,500 digg stories and calculate their macroscopic and microscopic properties.   we identify several trends in cascade dynamics : spreading via chaining, branching and community.   we discuss how these affect the spread of the story through the digg social network.   our computational framework is general and offers a practical solution to quantitative analysis of the microscopic structure of even very large cascades.
one potential star - planet interaction mechanism for hot jupiters involves planetary heating via currents set up by interactions between the stellar wind and planetary magnetosphere.   early modeling results indicate that such currents, which are analogous to the terrestrial global electric circuit ( gec ), have the potential to provide sufficient heating to account for the additional radius inflation seen in some hot jupiters. here   we present a more detailed model of this phenomenon, exploring the scale of the effect, the circumstances under which it is likely to be significant, implications for the planetary magnetospheric structure, and observational signatures.
several experimental groups are currently working towards realizing quasi - one - dimensional ( 1d ) atom de broglie waveguides and loading them with ultracold atoms.   the dynamics becomes truly 1d in a regime ( tonks gas ) of low temperatures and densities, and large positive scattering lengths for which the transverse mode becomes frozen, in which case the many - body schrdinger dynamics becomes exactly soluble via a fermi - bose mapping theorem. in this paper   we review our recent work on the exact ground state and quantum dynamics of 1d tonks gases and assess the possibilty of approaching the tonks regime using bessel beam optical dipole traps.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )
we investigate the effect of spatial symmetries on phase coherent electronic transport through chaotic quantum dots. for systems which have a spatial symmetry that interchanges the source and drain leads  , we find in the framework of random matrix theory that the density of the transmission eigenvalues is independent of the number of channels @xmath0 in the leads. as a consequence,   the weak localization correction to the conductance vanishes in these systems, and the shot noise suppression factor @xmath1 is independent of @xmath0.   we confirm this prediction by means of numerical calculations for stadium billiards with various lead geometries.   these calculations also uncover transport signatures of partially preserved symmetries.
models for the integrated relativistic electron population in clusters of galaxies are presented.   the results depend on the history of electron acceleration in the cluster.   if there is no present particle acceleration or other sources, then no high energy electrons ( @xmath0, @xmath1 mev ) should be present due to inverse compton ( ic ) losses.   high energy electrons are present if particle acceleration is occurring at present, perhaps as a result of a cluster merger shock.   the resulting ic, synchrotron, and gamma - ray emission from these models has been calculated. in the models, extreme ultraviolet ( euv ) and   very soft x - ray emission are a nearly ubiquitous feature, because this emission comes from ic by electrons with the longest lifetimes in clusters.   diffuse uv and optical emission is also expected in most clusters, but at levels which will be difficult to observe.   hard x - ray tails and diffuse radio synchrotron emission are only expected in clusters with recent or current particle acceleration ; for example, this acceleration might be due to intracluster merger shocks.   gamma - ray observations at energies of around 100 mev should detect both the dominant population of relativistic electrons and the corresponding ions.   the predicted fluxes are easily detectable with glast.
the scheme of the xuv / x - ray free electron laser based on the optical undulator created by two overlapped transverse laser beams is analyzed. a kinetic theoretical description and an _ ad hoc _ numerical model are developed to account for the finite energy spread, angular divergence and the spectral properties of the electron beam in the optical lattice.   the theoretical findings are compared to the results of the one- and three - dimensional numerical modeling with the spectral free electron laser code plares.
the generic matrix - matrix multiplication ( gemm ) is arguably the most popular computational kernel of the 20th century. yet,   surprisingly, no common methodology for evaluating gemm performance has been established over the many decades of using gemm for comparing architectures, compilers and ninja - class programmers.   we introduce gemmbench, a framework and methodology for evaluating performance of gemm implementations.   gemmbench is implemented on top of collective knowledge ( ck ), a lightweight framework for reproducible and collaborative r&d in computer systems.   using ck allows the r&d community to crowdsource hand - written and compiler - generated gemm implementations and to study their performance across multiple platforms, data sizes and data types.   our initial implementation supports hand - written opencl kernels operating on matrices consisting of single- and double - precision floating - point values, and producing single or multiple output elements per work - item ( via thread coarsening and vectorization ).
we propose and demonstrate a laser frequency stabilization scheme which generates a dispersion - like tunable doppler - free dichroic lock ( tdfdl ) signal.   this signal offers a wide tuning range for lock point ( i.e. zero - crossing ) without compromising on the slope of the locking signal.   the method involves measurement of magnetically induced dichroism in an atomic vapour for a weak probe laser beam in presence of a counter propagating strong pump laser beam.   a simple model is presented to explain the basic principles of this method to generate the tdfdl signal.   the spectral shift in the locking signal is achieved by tuning the frequency of the pump beam.   the tdfdl signal is shown to be useful for locking the frequency of a cooling laser used for magneto - optcal trap ( mot ) for @xmath0 atoms.
configuration interaction in many - electron atoms may cause anomalies in the fine structure which make the intervals small and very sensitive to variation of the fine structure constant. repeated precision measurements of these intervals over long period of time can put strong constrain on possible time variation of the fine structure constant.   we consider the @xmath0p@xmath1 fine structure multiplet in the ground state of neutral tellurium as an example. here   the effect of change of the fine structure constant is enhanced about one hundred times in the relative change of the small energy interval between the @xmath2p@xmath3 and @xmath2p@xmath4 states.
calculations have been performed for the @xmath0o(@xmath1,pn ) and the @xmath0o(@xmath1,pp ) reaction in the photon - energy range @xmath2 = 60 - 300 mev.   besides the contribution from the more common photoabsorption on the pionic degrees of freedom, we have investigated the influence of heavier meson exchange ( @xmath3 ) and intermediate @xmath4 creation with @xmath5 and @xmath6 exchange. whereas the @xmath5 meson is found to set the main trends, the @xmath6 meson is found not to be discardable in a theoretical description of the ( @xmath1,pn ) reaction.   the incorporation of an energy dependence and a decay width in the @xmath4 propagator is observed to be essential in order to arrive at a more realistic description of ( @xmath1,nn ) reactions at higher photon energies.    * absorption mechanisms in photon induced two - body knockout * +    l. machenil, m. vanderhaeghen, j. ryckebusch + and m. waroquier   +    _ laboratory for nuclear physics and laboratory for theoretical physics, + proeftuinstraat 86, 9000 gent, belgium _
based on previous results of digital topology, this paper focuses on algorithms of topological invariants of objects in 2d and 3d digital spaces.   we specifically interest in solving hole counting of 2d objects and genus of closed surface in 3d.   we first prove a new formula for hole counting in 2d.   the number of of holes is @xmath0 where @xmath1 and @xmath2 are sets of inward and outward corner points, respectively.   this paper mainly deals with algorithm design and implementation of practical computation of topological invariants in digital space.   the algorithms relating to data structures, and pathological case detection and original data modification are main issues.   this paper designed fast algorithms for topological invariants such as connected components, hole counting in 2d and boundary surface genus for 3d. for 2d images, we designed a linear time algorithm to solve hole counting problem. in 3d, we designed also @xmath3 time algorithm to get genus of the closed surface.   these two algorithms are both in @xmath4 space complexity.   space, number of holes, genus of surfaces, algorithm, time and space complexity
we theoretically explore photoassociation by adiabatic passage of two colliding cold @xmath0rb atoms in an atomic trap to form an ultracold rb@xmath1 molecule.we consider the incoherent thermal nature of the scattering process in a trap and show that coherent manipulations of the atomic ensemble, such as adiabatic passage, are feasible if performed within the coherence time window dictated by the temperature, which is relatively long for cold atoms.   we show that a sequence of @xmath2 pulses of moderate intensities, each lasting @xmath3 ns, can photoassociate a large fraction of the atomic ensemble at temperature of @xmath4 @xmath5k and density of @xmath6 atoms/@xmath7.   use of multiple pulse sequences makes it possible to populate the ground vibrational state. employing spontaneous decay from a selected excited state  , one can accumulate the molecules in a narrow distribution of vibrational states in the ground electronic potential.   alternatively, by removing the created molecules from the beam path between pulse sets, one can create a low - density ensemble of molecules in their ground ro - vibrational state.
we provide a study of the phenomenology of heterotic orbifold compactifications scenarii within the context of supergravity effective theories.   our investigation focuses on those models where the soft lagrangian is dominated by loop contributions to the various soft supersymmetry breaking parameters, giving a mixed anomaly - gravity mediation model.   we consider the pattern of masses that are governed by these soft terms and investigate the implications of certain indirect constraints on supersymmetric models. in this framework  , we point out how the complementarity between direct and indirect detection of a neutralino dark matter, and futur accelerator prospects can reduce considerably the parameter space of such models
we measured the linear polarization of sagittarius a * to be @xmath0 at 230 ghz using the bima array with a resolution of @xmath1 arcsec.   this confirms the previously reported detection with the jcmt 14-m antenna.   our high resolution observations demonstrate that the polarization does not arise from dust but from a synchrotron source associated with sgr a*. we see no change in the polarization position angle and only a small change in the polarization fraction in four observations distributed over 60 days.   we find a position angle @xmath2 degrees that differs substantially from what was found in earlier jcmt observations at the same frequency.   polarized dust emission can not account for this discrepancy leaving variability and observational error as the only explanations.   the bima observations alone place an upper limit on the magnitude of the rotation measure of @xmath3.   these new observations when combined with the jcmt observations at 150, 375 and 400 ghz suggest @xmath4. this rm may be caused by an external faraday screen. barring a special geometry or a high number of field reversals, this rm rules out accretion rates greater than @xmath5.   this measurement is inconsistent with high accretion rates necessary in standard advection dominated accretion flow and bondi - hoyle models for sgr a*. it argues for low accretion rates as a major factor in the overall faintness of sgr a*.
we investigate the composition and the equation of state of the kaon condensed phase in neutrino - free and neutrino - trapped star matter within the framework of the brueckner - hartree - fock approach with three - body forces.   we find that neutrino trapping shifts the onset density of kaon condensation to a larger baryon density, and reduces considerably the kaon abundance. as a consequence, when kaons are allowed, the equation of state of neutrino - trapped star matter becomes stiffer than the one of neutrino free matter.   the effects of different three - body forces are compared and discussed.   neutrino trapping turns out to weaken the role played by the symmetry energy in determining the composition of stellar matter, and thus reduces the difference between the results obtained by using different three - body forces.
the use of hyperasymptotics and the weniger transformation has been proposed, in a joint fashion, for decoding the divergent asymptotic series generated by the steepest descent on a wide class of saddle - point integrals evaluated across stokes sets [ r. borghi, phys.   rev.   e * 78, * 026703 ( 2008 ) ]. in the present sequel,   the full development of the h - wt up to the second order in h is derived.   numerical experiments, carried out on several classes of saddle - point integrals, including the swallowtail diffraction catastrophe, show the effectiveness of the 2nd - level h - wt, in particular when the integrals are evaluated beyond the asymptotic realm.
we present the @xmath0977, @xmath11032, 1038 and @xmath01486 emission line maps of the cygnus loop, obtained with the newly processed data of spectroscopy of plasma evolution from astrophysical radiation ( spear ; also known as fims ) mission.   in addition, the + line complexes around 1400  are resolved into two separate emission lines, whose intensity demonstrates a relatively high region predicted in the previous study. the morphological similarity between the and x - ray images, as well as a comparison of the intensity with the value expected from the x - ray results, indicates that large portions of the observed emissions could be produced from x - ray emitting gas.   comparisons of the far - ultraviolet ( fuv ) images with the optical and 21 cm images, reveal spatial variations of shock - velocity populations and high fuv extinction in the direction of a previously identified cloud. by calculating the fuv line ratios for several subregions of the cygnus loop  , we investigate the spatial variation of the population of radiative shock velocities ; and the effects of resonance scattering, x - ray emitting gas, and non - radiative shocks.   the fuv and x - ray luminosity comparisons between the cygnus loop and the vela supernova remnant suggest that the fraction of shocks in the early evolutionary stages is much larger in the cygnus loop.
most luminous infrared galaxies ( ligs ) are closely interacting / merging systems rich in molecular gas.   we study here the relationship between the stage of the galaxy - galaxy interactions, the molecular gas mass, and the star formation rate as deduced from the infrared luminosity @xmath0 in ligs.   we find a correlation between the co(1 - 0 ) luminosity ( a measure of molecular mass m(h@xmath1 ) ) and the projected separation of merger nuclei ( indicator of merging stages ) in a sample of 50 lig mergers, which shows that the molecular gas content decreases as merging advances.   the starburst is due to enhanced star formation in pre  existing molecular clouds and not to the formation of more molecular clouds from hi.   the molecular content is being rapidly depleted due to the starbursts as merging progresses.   this is further supported by an anti - correlation between @xmath2(h@xmath1 ), the global measure of the star formation rate per unit gas mass, and the projected separation implying an enhanced star formation `` efficiency '' in late stage mergers compared to that of early mergers.   this is the first evidence connecting the depletion of molecular gas with starbursts in interacting galaxies.
a kinetic - rate equation approach in a thermally expanding medium is employed to calculate the evolution of charmonium and bottomonium distributions in heavy - ion collisions.   the equilibrium properties of the quarkonia are taken from in - medium spectral functions which are schematically constrained by euclidean correlators from lattice qcd.   the initial conditions for the rate equation ( heavy - flavor cross sections, nuclear absorption ) and the thermal evolution are constrained by data as available.   after fixing two free parameters to describe charmonium data at sps and rhic, the predictions for lhc are discussed in light of recent data.
we study the onset of patterns in vertically oscillated layers of frictionless dissipative particles. using both numerical solutions of continuum equations to navier - stokes order and molecular dynamics ( md ) simulations,   we find that standing waves form stripe patterns above a critical acceleration of the cell.   changing the frequency of oscillation of the cell changes the wavelength of the resulting pattern ; md and continuum simulations both yield wavelengths in accord with previous experimental results.   the value of the critical acceleration for ordered standing waves is approximately 10% higher in molecular dynamics simulations than in the continuum simulations, and the amplitude of the waves differs significantly between the models.   the delay in the onset of order in molecular dynamics simulations and the amplitude of noise below this onset are consistent with the presence of fluctuations which are absent in the continuum theory.   the strength of the noise obtained by fit to swift - hohenberg theory is orders of magnitude larger than the thermal noise in fluid convection experiments, and is comparable to the noise found in experiments with oscillated granular layers and in recent fluid experiments on fluids near the critical point.   good agreement is found between the mean field value of onset from the swift - hohenberg fit and the onset in continuum simulations.   patterns are compared in cells oscillated at two different frequencies in md ; the layer with larger wavelength patterns has less noise than the layer with smaller wavelength patterns.
results from the arecibo hi strip survey, an unbiased extragalactic hi survey, combined with optical and 21 cm follow - up observations, determine the hi mass function and the cosmological mass density of hi at the present epoch. both are consistent with earlier estimates, computed for the population of optically selected galaxies.   this consistency occurs because, although the distribution of optical central surface brightnesses among galaxies is flat, we fail to find a population of galaxies with central surface brightnesses fainter than 24  @xmath0-@xmath1, even though there is no observational selection against them.   = 2em    = 17.5 cm = 24.6 cm = -2.5 cm = -1.0 cm = -1.0 cm    * keywords : * galaxies : luminosity function, mass function ; surveys
we propose a multilevel quantum heat engine with a working medium described by a generalized rabi model which consists of a two - level system coupled to a single mode bosonic field.   the model is constructed to be a continuum limit of a quantum biological description of light harvesting complexes so that it can amplify quantum coherence by a mechanism which is a quantum analog of classical huygen s clocks.   the engine operates in quantum otto cycle where the working medium is coupled to classical heat baths in the isochoric processes of the four stroke cycle ; while either the coupling strength or the resonance frequency is changed in the adiabatic stages.   we found that such an engine can produce work with an efficiency close to carnot bound when it operates at low temperatures and in the ultrastrong coupling regime.   interplay of quantum coherence and quantum correlations on the engine performance is discussed in terms of second order coherence, quantum mutual information and logarithmic negativity of entanglement.   we point out that the proposed quantum otto engine can be implemented experimentally with the modern circuit quantum electrodynamic systems where flux qubits can be coupled ultrastrongly to superconducting transmission line resonators.
the amplitudes of @xmath0-meson decays are calculated in a relativistic nonperturbative quark model which assumes that mesons are made of a quark antiquark pair and of a scalar neutral component representing the contribution of the nonelementary fluctuations of the quark gluonic field.   the experimental data can be fitted in a satisfactory manner using current quark masses @xmath1.   -0.6 cm    _ ifa - ft-395 - 1994 _    * *    @xmath2    * and @xmath3 decays *    * *    institute of atomic physics    theoretical ph ysics department    bucharest pobox mg-6, romania
at the center of the milky way, with a distance of @xmath08  kpc, the compact source sagittarius  a * ( sgra * ) can be associated with a super massive black hole of @xmath04@xmath110@xmath2m@xmath3 .   sgra * shows strong variability from the radio to the x - ray wavelength domains.   here we report on simultaneous nir / sub - millimeter / x - ray observations from may 2007 that involved the naco adaptive optics ( ao ) instrument at the european southern observatory s very large telescope, the australian telescope compact array ( atca ), the us mm - array carma, the iram  30 m mm - telescope, and other telescopes.   we concentrate on the time series of mm / sub - mm data from carma, atca, and the mambo bolometer at the iram 30 m telescope.
description of a nuclear system in its ground state and at low excitations based on the equation of state ( eos ) around normal density is presented. in the expansion of the eos around the saturation point additional spin polarization terms   are taken into account.   these terms, together with the standard symmetry term, are responsible for appearance of the @xmath0-like clusters in the ground state configurations of the n = z even - even nuclei. at the nuclear surface   these clusters can be identified as alpha particles.   a correction for the surface effects is introduced for atomic nuclei.   taking into account an additional interaction between clusters the binding energies and sizes of the considered nuclei are very accurately described.   the limits of the eos parameters are established from the properties of the @xmath0, @xmath1he and @xmath2 particles.
the spi anticoincidence shield consists of 91 bgo crystals and is operated as a nearly omnidirectional gamma - ray burst detector above  75 kev. since the start of the mission 269 gamma - ray burst candidates have been detected.   110 bursts have been confirmed with the instruments included in the 3rd interplanetary network.   here we present a preliminary statistical analysis of the spi - acs sample of gamma - ray bursts and gamma - ray burst candidates ; in particular we discuss the duration distribution of the bursts.   a prominent population of short burst candidates ( duration @xmath0200ms ) is found which is discovered to be strongly contaminated by cosmic - ray nuclei interacting in the detectors.   
we present a two - flavour linear sigma model with global chiral symmetry and vector and axial - vector mesons.   we calculate @xmath0 scattering lengths and the decay widths of scalar, vector, and axial - vector mesons.   it is demonstrated that vector and axial - vector meson degrees of freedom play an important role in these low - energy processes and that a reasonable theoretical description requires globally chirally invariant terms other than the vector meson mass term.   an important question for meson vacuum phenomenology is the quark content of the physical scalar @xmath1 and @xmath2 mesons.   we investigate this question by assigning the quark - antiquark @xmath3 and @xmath4 states of our model with these physical mesons.   we show via a detailed comparison with experimental data that this scenario can describe all vacuum properties studied here except for the decay width of the @xmath3, which turns out to be too small.   we also study the alternative assignment @xmath5 and @xmath6 for the scalar mesons. in this case   the decay width agrees with the experimental value, but the @xmath0 scattering length @xmath7 is too small.   this indicates the necessity to extend our model by additional scalar degrees of freedom.
we investigate the electrical control of the exchange coupling ( j ) between donor bound electrons in silicon with a detuning gate bias, crucial for the implementation of the two - qubit gate in a silicon quantum computer.   we find the asymmetric 2p-1p system provides a highly tunable exchange - curve with mitigated j - oscillation, in which 5 orders of magnitude change in the exchange energy can be achieved using a modest range of electric field for 15 nm qubit separation.   compared to the barrier gate control of exchange in the kane qubit, the detuning gate design reduces the demanding constraints of precise donor separation, gate width, density and location, as a range of j spanning over a few orders of magnitude can be engineered for various donor separations.   we have combined a large - scale full band atomistic tight - binding method with a full configuration interaction technique to capture the full two - electron spectrum of gated donors, providing state - of - the - art calculations of exchange energy in 1p-1p and 2p-1p qubits.    * *
in this paper, we analyse the effect of the expansion of the universe on the clustering of galaxies.   we evaluate the configurational integral for interacting system of galaxies in an expanding universe by including effects produced by the cosmological constant.   the gravitational partition function is obtained using this configuration integral.   thermodynamic quantities, specifically, helmholtz free energy, entropy, internal energy, pressure and chemical potential are also derived for this system.   it is observed that they depend on the modified clustering parameter for this system of galaxies.   it is also demonstrated that these thermodynamical quantities get corrected because of the cosmological constant.   cosmology : theory dark energy ; clusters : general   gravitation- fluctuation large scale structure of universe method ; analytical
we analyze the dynamics of model supercooled liquids in a temperature regime where predictions of mode coupling theory ( mct ) are known to be valid qualitatively. in this regime,   the adam - gibbs ( ag ) relation, based on an activation picture of dynamics also describes the dynamics satisfactorily, and we explore the mutual consistency and interrelation of these descriptions. although entropy and dynamics are related via phenomenological theories, the connection between mct and entropy has not been argued for. in this work   we explore this connection and provide a microscopic derivation of the phenomenological rosenfeld theory. at low temperatures   the overlap between mct power law regime and ag relation implies that the ag relation predicts an avoided divergence at @xmath0, the origin of which is traced back to the vanishing of pair configurational entropy, which we find occurs at the same temperature.   we also show that the residual multiparticle entropy plays an important role in describing the relaxation time.
it is now reasonably clear that disc fragmentation can only operate in the outer parts of protostellar discs ( @xmath0 au ).   it is also expected that any object that forms via disc fragmentation will have an initial mass greater than that of jupiter. however, whether or not such a process actually operates, or can play a significant role in the formation of planetary - mass objects, is still unclear.   we do have a few examples of directly imaged objects that may have formed in this way, but we have yet to constrain how often disc fragmentation may actually form such objects.   what we want to consider here is whether or not we can constrain the likely population of planetary - mass objects formed via disc fragmentation by considering how a population of objects at large radii ( @xmath1 ) au - if they do exist - would evolve under perturbations from more distant stellar companions.   we find that there is a specific region of parameter space to which such objects would be scattered and show that the known exoplanets in that region have properties more consistent with that of the bulk exoplanet population, than with having been formed via disc fragmentation at large radii.   along with the scarcity of directly - imaged objects at large radii, our results provide a similar, but independent, constraint on the frequency of objects formed via disc fragmentation.       planets and satellites : formation - planets and satellites : general - planets and satellites : gaseous planets - stars : formation - ( stars : ) brown dwarfs
the popular, stable, robust and computationally inexpensive cubic spline interpolation algorithm is adopted and used for finite temperature green s function calculations of realistic systems. we demonstrate that with appropriate modifications the temperature dependence can be preserved while the green s function grid size can be reduced by about two orders of magnitude by replacing the standard matsubara frequency grid with a sparser grid and a set of interpolation coefficients.   we benchmarked the accuracy of our algorithm as a function of a single parameter sensitive to the shape of the green s function. through numerous examples  , we confirmed that our algorithm can be utilized in a systematically improvable, controlled, and black - box manner and highly accurate one- and two - body energies and one - particle density matrices can be obtained using only around 5% of the original grid points.   additionally, we established that to improve accuracy by an order of magnitude, the number of grid points needs to be doubled, whereas for the matsubara frequency grid an order of magnitude more grid points must be used.   this suggests that realistic calculations with large basis sets that were previously out of reach because they required enormous grid sizes may now become feasible.
we present our new photometry of dv psc obtained in 2010 and 2011, and new spectroscopic observation on feb.   14, 2012. during our observations,   three flare - like events might be detected firstly in one period on dv psc.   the flare rate of dv psc is about 0.017 flares per hour. using wilson - devinney program, we derived the preliminary starspot parameters.   moreover, the magnetic cycle is 9.26(@xmath0 ) year analyzed by variabilities of max.i - max.ii.
in this paper we study the geometry and the thermodynamics of a _ holographic screen _ in the framework of the ultraviolet self - complete quantum gravity. to achieve this goal   we construct a new static, neutral, non - rotating black hole metric, whose outer ( event ) horizon coincides with the surface of the screen.   the space - time admits an extremal configuration corresponding to the minimal holographic screen and having both mass and radius equalling the planck units.   we identify this object as the space - time fundamental building block, whose interior is physically unaccessible and can not be probed even during the hawking evaporation terminal phase. in agreement with the holographic principle, relevant processes take place on the screen surface.   the area quantization leads to a discrete mass spectrum.   an analysis of the entropy shows that the minimal holographic screen can store only one byte of information while in the thermodynamic limit the area law is corrected by a logarithmic term.
we investigate quasinormal modes(qnms ) and hawking radiation of a reissner - nordstrm black hole surrounded by quintessence.   the wentzel - kramers - brillouin ( wkb ) method is used to evaluate the qnms and the rate of radiation.   the results show that due to the interaction of the quintessence with the background metric, the qnms of the black hole damp more slowly when increasing the density of quintessence and the black hole radiates at slower rate.
we compare the distribution of molecular gas and star formation activity in the bar region of six spirals ( ngc 2903, ngc 3627, ngc 4321, ngc 5457, ngc 6946, & ic 342 ) from the bima survey of nearby galaxies ( song ). the molecular gas, traced using the co ( j=10 ) emission line, is brightest along the leading edge of the stellar bar in the bar dust lanes. the star formation activity, traced using the h@xmath0  emission line, is offset towards the leading side of the co emission.   a cross - correlation analysis shows that a ) the hii regions are offset 0800 pc on the leading side of the co emission, b ) the largest offsets are found in the strongest bars, and c ) there is a wide range in offsets in a single bar with no systematic pattern as a function of the galacto - centric radius.   the co - h@xmath0  offset constrains how stars may form depending on the gas flow.   we examine possible star formation scenarios in context of the two main classes of bar gas flow simulations, the n - body / sticky particle and hydrodynamic models.   though both model gas flows are generally consistent with the observed offsets, we suggest the inclusion of a two- or multi - phase medium to improve the agreement between models and observation.
a mathematical approach to investigate particle acceleration at shock waves moving at arbitrary speed in a medium with arbitrary scattering properties was first discussed in @xcite.   we use this method and somewhat extend it in order to include the effect of a large scale magnetic field in the upstream plasma, with arbitrary orientation with respect to the direction of motion of the shock.   we also use this approach to investigate the effects of anisotropic scattering on spectra and anisotropies of the distribution function of the accelerated particles.
we have simulated the evolution of a large sample of x - ray clusters in a @xmath0cdm universe at high spatial resolution using adaptive mesh refinement and placed the results in an online archive for public access.   the simulated cluster archive website sca.ncsa.uiuc.edu provides tools for interactive 2d and 3d analysis of gas and dark matter fields, x - ray and sz imaging, and data export.   we encourage community use and solicit their feedback.
this paper aims to validate the @xmath0-ginibre point process as a model for the distribution of base station locations in a cellular network.   the @xmath0-ginibre is a repulsive point process in which repulsion is controlled by the @xmath0 parameter.   when @xmath0 tends to zero, the point process converges in law towards a poisson point process.   if @xmath0 equals to one it becomes a ginibre point process.   simulations on real data collected in paris ( france ) show that base station locations can be fitted with a @xmath0-ginibre point process.   moreover we prove that their superposition tends to a poisson point process as it can be seen from real data.   qualitative interpretations on deployment strategies are derived from the model fitting of the raw data.
the dilepton production in elementary @xmath0 reactions at bevalac energies @xmath1 gev is investigated.   the calculations include direct @xmath2 decays of the vector mesons @xmath3, @xmath4, and @xmath5, dalitz decays of the @xmath6-, @xmath7-, @xmath8-, @xmath4-, and @xmath5-mesons, and of the baryon resonances @xmath9 @xmath10.   the subthreshold vector meson production cross sections in @xmath11 collisions are treated in a way sufficient to avoid double counting with the inclusive vector meson production.   the vector meson dominance model for the transition form factors of the resonance dalitz decays @xmath12 is used in an extended form to ensure correct asymptotics which are in agreement with the quark counting rules.   such a modification gives an unified and consistent description of both @xmath13 radiative decays and @xmath14 meson decays.   the effect of multiple pion production on the experimental efficiency for the detection of the dilepton pairs is studied.   we find the dilepton yield in reasonable agreement with the experimental data for the set of intermediate energies whereas at the highest energy @xmath15 gev the number of dilepton pairs is likely to be overestimated experimentally in the mass range @xmath16 mev.
a unified treatment of mass varying dark matter coupled to cosmon-_like _ dark energy is shown to result in _ effective _ generalized chaplygin gas ( gcg ) scenarios.   the mass varying mechanism is treated as a cosmon field inherent effect.   coupling dark matter with dark energy allows for reproducing the conditions for the present cosmic acceleration and for recovering the stability resulted from a positive squared speed of sound @xmath0, as in the gcg scenario.   the scalar field mediates the nontrivial coupling between the dark matter sector and the sector responsible for the accelerated expansion of the universe.   the equation of state of perturbations is the same as that of the background cosmology so that all the effective results from the gcg paradigm are maintained.   our results suggest the mass varying mechanism, when obtained from an exactly soluble field theory, as the right responsible for the stability issue and for the cosmic acceleration of the universe.
we report the experimental study of the degassing dynamics through a thin layer of shear - thinning viscoelastic fluid ( ctab / nasal solution ), when a constant air flow is imposed at its bottom. over a large range of parameters  , the air is periodically released through series of successive bubbles, hereafter named _   cascades_. each cascade is followed by a continuous degassing, lasting for several seconds, corresponding to an open channel crossing the fluid layer.   the periodicity between two cascades does not depend on the injected flow - rate. inside one cascade,   the properties of the overpressure signal associated with the successive bubbles vary continuously.   the pressure threshold above which the fluid starts flowing, fluid deformation and pressure drop due to degassing through the thin fluid layer can be simply described by a maxwell model.   we point out that monitoring the evolution inside the cascades provides a direct access to the characteristic relaxation time associated with the fluid rheology.
recent findings indicate that the monogem ring supernova remnant (  snr  ) and the associated pulsar psr b0656 + 14 may be the ` single source'responsible for the formation of the sharp knee in the cosmic ray energy spectrum at @xmath03pev.   we estimate the contribution of the pulsar b0656 + 14 to the cosmic rays in the pev region and conclude that the pulsar can not contribute more than 15% to the cosmic ray intensity at the knee  . therefore it can not be the dominant source there and an snr is still needed.   we also examine the possibility of the pulsar giving the peak of the extensive air shower (  eas  ) intensity observed from the region inside the monogem ring.   the estimates of the gamma - ray flux produced by cosmic ray particles from this pulsar indicate that it can be the source of the observed peak, if the particles were confined within the snr during a considerable fraction of its total age.   we also estimate the contribution of geminga and vela pulsars to cosmic rays at the knee.
we use tools from the theory of dynamical systems with symmetries to stratify uhlmann s standard purification bundle and derive a new connection for mixed quantum states. for unitarily evolving systems, this connection gives rise to the ` interferometric'geometric phase of sjqvist _   et al. _   [ phys.   rev.   lett.   85 2845 - 2849 ( 2000 ) ], and for more generally evolving open systems it gives rise to the generalization of the interferometric geometric phase due to tong _   et al. _   [ phys.   rev.   lett.   93 080405 ( 2004 ) ].
we investigate advection dominated, transsonic accretion flows in the vicinity of a kerr black hole.   we take into account all relativistic effects in the dynamics of the flow and in the propagation of light.   we assume the matter to be weakly magnetized and cool via the thermal synchrotron and bremsstrahlung radiation.   we include also the effects of comptonization.   we calculate the spectra of radiation as seen by observers located at different positions relative to the equatorial plane of the disk.   the radiation emitted by the accreting matter is anisotropic and observers near the equatorial plane register a higher energy flux. this effect is more pronounced in the case of slowly rotating black holes. we calculate also the shape of a hypothetical gamma line, which may be produced by the thermonuclear reactions in the inner part of the flow  . the line is strongly broadened, but the fact that the flow is quasi - spherical removes the two - peak shape of the line seen in the spectra emitted from thin, keplerian disks.   the kinematics of the advection dominated flows is not unique ( as opposed to keplerian disks or spherical free - fall ) and it would probably be difficult to find strong limits on source models using the spectral observations.    epsf.sty
social network has become one of the themes of government issues, mainly dealing with the chaos.   the use of web is steadily gaining ground in these issues.   however, most of the web documents are unstructured and lack of semantic. in this paper   we proposed an information retrieval driven method for dealing with heterogeneity of features in the web.   the proposed solution is to compare some approaches have shown the capacity to extract social relation : strength relations and relations based on online academic database.  , unsupervised, supervised, keyword, similarity, association rule, semantic.
the high resolution fly s eye ( hires ) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of @xmath0 and is sensitive to cosmic rays with energies above @xmath1ev.   hires is thus an excellent instrument for the study of the arrival directions of ultrahigh energy cosmic rays.   we present the results of a search for anisotropies in the distribution of arrival directions on small scales ( @xmath2 ) and at the highest energies ( @xmath3  ev ).   the search is based on data recorded between 1999 december and 2004 january, with a total of 271 events above @xmath4ev.   no small - scale anisotropy is found, and the strongest clustering found in the hires stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.
dielectronic recombination ( dr ) of few - electron ions has evolved into a sensitive spectroscopic tool for highly charged ions.   this is due to technological advances in electron - beam preparation and ion - beam cooling techniques at heavy - ion storage rings.   recent experiments prove unambiguously that dr collision spectroscopy has become sensitive to 2nd order qed and to nuclear effects.   this review discusses the most recent developments in high - resolution spectroscopy of low - energy dr resonances, experimental studies of kll dr of very heavy hydrogenlike ions, isotope shift measurements of dr resonances, and the experimental determination of hyperfine induced decay rates in divalent ions utilizing dr.   dielectronic recombination, hyperfine splitting, isotope shift, breit interaction, heavy - ion storage - ring 34.80.lx, 31.30.gs, 31.30.j-, 32.70.cs
we propose a model that provides a unified description of nuclear equation of state and fragmentations.   the equation of state is evaluated in bragg - williams as well as in bethe - peierls approximations and compared with that in the mean field theory with skyrme interactions.   the model shows a liquid - gas type phase transition.   the nuclear fragment distributions are studied for different densities at finite temperatures.   power law behavior for fragments is observed at critical point.   the study of fragment distribution and the second moment @xmath0 shows that the thermal critical point coincides with the percolation point at the critical density.   high temperature behavior of the model shows characteristics of chemical equilibrium.    0.5 cm
many random processes can be simulated as the output of a deterministic model accepting random inputs.   such a model usually describes a complex mathematical or physical stochastic system and the randomness is introduced in the input variables of the model.   when the statistics of the output event are known, these input variables have to be chosen in a specific way for the output to have the prescribed statistics. because the probability distribution of the input random variables is not directly known but dictated implicitly by the statistics of the output random variables, this problem is usually intractable for classical sampling methods. based on markov chain monte carlo   we propose a novel method to sample random inputs to such models by introducing a modification to the standard metropolis - hastings algorithm. as an example we consider a system described by a stochastic differential equation ( sde ) and demonstrate how sample paths of a random process satisfying this sde can be generated with our technique.   models with random input, markov chain monte carlo, sampling methods, stochastic differential equations    65c20, 65c40, 65c05, 62p30
we derived a two - dimensional map of the molecular fraction, @xmath0, ( ratio of the molecular gas density to that of total gas ) in the spiral galaxy m51, and examined the behavior of molecular fronts ( mf ), where mf represents the place where @xmath0 changes drastically from nearly zero to unity and vice versa.   we show that the mf phenomenon occurs not only radial, but also in the azimuth direction through the spiral arms, and @xmath0 changes rapidly in the arm - to - inter - arm transition regions.   the existence of the azimuthal mf indicates that the atomic gas ( hi ) is quickly transformed to molecular gas ( h@xmath1 ) during the passage through spiral arms.   we performed a numerical simulation of mf based on an hi - to-  phase transition theory, and reproduced the observations.   we estimated a azimuthal scale length of the transition to be less than 200 pc, corresponding to a time scale of @xmath2 2 myr for  gas formation.   the azimuthal width of a molecular arm is estimated to be at most 2.5 kpc, where the gas can remain in molecular phase for about 25 myr.   kew words : galaxies : spiral  galaxies : ism  galaxies : cluster of  molecular gas  hi gas    = 15truecm = 22truecm    
double lined spectroscopic binaries in an evolved stage of evolution are expected to be extremely rare since they must consist of equally luminous and thus almost equally evolved objects, which requires an extremely similar initial mass. in this contribution we discuss such rare double evolved sb2 system : hd172481.   this binary includes an f - type post - agb object and an m - type agb companion.   the spectrum shows a surprisingly strong lii 670.8 nm line with an equivalent width of @xmath0=54m, yielding a lithium abundance of @xmath1.   several explanations for this huge lithium content are explored.   _ to appear in the proceedings of the conference : `` post - agb objects ( proto - planetary nebulae ) as a phase of stellar evolution '', held in toru, poland, july 5 - 7, 2000, eds.   r. szczerba, r. tylenda, and s.k.   gorny.
first results from a fully self - consistent, temperature - dependent equation of state that spans the whole density range of neutron stars and supernova cores are presented.   the equation of state ( eos ) is calculated using a mean - field hartree - fock method in three dimensions ( 3d ).   the nuclear interaction is represented by the phenomenological skyrme model in this work, but the eos can be obtained in our framework for any suitable form of the nucleon - nucleon effective interaction.   the scheme we employ naturally allows effects such as ( i ) neutron drip, which results in an external neutron gas, ( ii ) the variety of exotic nuclear shapes expected for extremely neutron heavy nuclei, and ( iii ) the subsequent dissolution of these nuclei into nuclear matter. in this way  , the equation of state is calculated across phase transitions without recourse to interpolation techniques between density regimes described by different physical models.   eos tables are calculated in the wide range of densities, temperature and proton / neutron ratios on the ornl nccs xt3, using up to 2000 processors simultaneously.
narrow - band h@xmath0+ and broadband r images and surface photometry are presented for a sample of 29 bright ( m@xmath1 -18 ) isolated s0-scd galaxies within a distance of 48 mpc.   these galaxies are among the most isolated nearby spiral galaxies of their hubble classifications as determined from the nearby galaxies catalog ( tully 1987a ).
pulsar timing observations are used to place constraints on the rate of coalescence of supermassive black - hole ( smbh ) binaries as a function of mass and redshift.   in contrast to the indirect constraints obtained from other techniques, pulsar timing observations provide a direct constraint on the black - hole merger rate. this is possible since pulsar timing is sensitive to the gravitational waves ( gws ) emitted by these sources in the final stages of their evolution.   we find that upper bounds calculated from the recently published parkes pulsar timing array data are just above theoretical predictions for redshifts below 10. in the future, with improved timing precision and longer data spans, we show that a non - detection of gws will rule out some of the available parameter space in a particular class of smbh binary merger models.   we also show that if we can time a set of pulsars to 10ns timing accuracy, for example, using the proposed square kilometre array, it should be possible to detect one or more individual smbh binary systems.
we study the bispectrum of the primordial curvature perturbation on uniform - density hypersurfaces generated by a kind of the noncanonical warm inflation, wherein the inflation is provided by a noncanonical scalar inflaton field that is coupled to radiation through a thermal dissipation effect.   we obtain an analytic form for the nonlinear parameter @xmath0 that describes the non - gaussianity in first - order cosmological perturbation theory and analyse the magnitude of this nonlinear parameter.   we make a comparison between our result and those of the standard inflation and the canonical warm inflation.   we also discuss when the contribution to the non - gaussianity due to the second - order perturbation theory becomes more important and what effect can be observed.   we take the dirac - born - infeld ( dbi ) inflation as a concrete example to find how the sound speed and the thermal dissipation strength to decide the non - gaussianity and to get a lower bound of the sound speed constrained by planck.
we deal with the task of supervised learning if the data is of functional type.   the crucial point is the choice of the appropriate fitting method ( also called learner ).   boosting is a stepwise technique that combines learners in such a way that the composite  boosted  learner outperforms the single learner.   this can be done by either reweighting the examples or with the help of a gradient descent technique. in this paper, we explain how to extend boosting methods to problems that involve functional data.    * keywords * : functional data analysis, boosting
superselection rules severly constrain the operations which can be implemented on a distributed quantum system.   while the restriction to local operations and classical communication gives rise to entanglement as a nonlocal resource, particle number conservation additionally confines the possible operations and should give rise to a new resource. in [ phys.rev.   lett.  * 92 *, 087904 ( 2004 ), ] we showed that this resource can be quantified by a single additional number, the superselection induced variance ( siv ) without changing the concept of entanglement. in this paper, we give the results on pure states in greater detail ; additionally, we provide a discussion of mixed state nonlocality with superselection rules where we consider both formation and distillation.   finally, we demonstrate that siv is indeed a resource, i.e., that it captures how well a state can be used to overcome the restrictions imposed by the superselection rule.
recent discoveries have confirmed the existence of a large population of x - ray sources fuelled by accretion from the stellar wind of an ob supergiant.   such systems are powerful laboratories to study many aspects of astrophysics. over the last decades, the physics of accretion in these systems has been the subject of extensive research, mainly through numerical methods. in spite of this effort,   large uncertainties remain in our understanding, reflecting the complexity of the physical situation.   a crucial issue that remains open is the possible formation of accretion discs. though the spin evolution of neutron stars in these systems suggests that angular momentum is, at least occasionally, accreted, and many observational facts seem to require the existence of discs, computational results do not favour this possibility. in this brief review  , i will summarise some of the open questions in this area.
i describe the computation of energy widths of nuclear states using an integral over the interaction region of _ ab initio _ variational monte carlo wave functions, and i present calculated widths for many states.   i begin by presenting relations that connect certain short - range integrals to widths.   i then present predicted widths for @xmath0 nuclei, and i compare them against measured widths.   they match the data more closely and with less ambiguity than estimates based on spectroscopic factors.   i consider the consequences of my results for identification of observed states in @xmath1b, @xmath2he, and @xmath2li.   i also examine failures of the method and conclude that they generally involve broad states and variational wave functions that are not strongly peaked in the interaction region. after examining bound - state overlap functions computed from a similar integral relation,   i conclude that overlap calculations can diagnose cases in which computed widths should not be trusted.
we show that nuclear motion of rydberg atoms can be induced by resonant dipole - dipole interactions that trigger the energy transfer between two energetically close rydberg states.   how and if the atoms move depends on their initial arrangement as well as on the initial electronic excitation. using a mixed quantum / classical propagation scheme we obtain the trajectories and kinetic energies of atoms, initially arranged in a regular chain and prepared in excitonic eigenstates.   the influence of off - diagonal disorder on the motion of the atoms is examined and it is shown that irregularity in the arrangement of the atoms can lead to an acceleration of the nuclear dynamics.
far ultraviolet ( fuv ) spectral images of the spica region are first presented here for the @xmath0 @xmath11533.4 and @xmath11670.8 lines and then compared with the optical h@xmath2 image.   the h@xmath2 and @xmath0 images show enhanced emissions in the southern part of the region where density increases outwards.   this high density region, which we identify as part of the  interaction ring " of the loop i superbubble and the local bubble, seems to bound the southern region. on the other hand, the observed profile of shows a broad central peak, without much difference between the northern and southern parts, which we suspect results from multiple resonant scattering.   the extended tails seen in the radial profiles of the fuv intensities suggest that the nebula may be embedded in a warm ionized gas.   simulation with a spectral synthesis code yields the values of the lyman continuum luminosity and the effective temperature of the central star similar to previous estimates with @xmath3 photons s@xmath4 and 26,000 k, respectively, but the density of the northern region, 0.22 @xmath5, is much smaller than previous estimates for the h@xmath2 brightest region.
the separation of a heavy quark and antiquark pair leads to the formation of a tube of flux, or `` string '', which should break in the presence of light quark - antiquark pairs.   this expected zero - temperature phenomenon has proven elusive in simulations of lattice qcd. in an extension of work reported last year we present clear evidence for string breaking in qcd with two flavors of dynamical staggered sea quarks and apply our results to a simple three - state mixing model for string breaking.   we find that mixing is weak and falls to zero at level crossing.
let @xmath0 be the finite field of cardinality @xmath1.   for all large @xmath2, any subset @xmath3 of cardinality @xmath4 must contain three points @xmath5 for @xmath6 and @xmath7.   our argument is an elaboration of an argument of shkredov @xcite, building upon the finite field analog of ben green @xcite.   the interest in our result is in the exponent on @xmath8, which is larger than has been obtained previously.
we utilize the complimentary capabilities of and, to conduct a detailed imaging and spectral study of the nearby galaxy ngc 4945 focussing on its nucleus and immediate surroundings ( within @xmath0 kpc of the nucleus ).   a complex morphology is revealed including a predominantly hard, but partially resolved, nuclear source plus a spectrally soft, conically shaped x - ray `` plume '', which extends @xmath1 ( 500 pc ) to the northwest. in ngc 4945 our direct view of the active galactic nucleus ( agn )   is blocked below @xmath2 kev by extremely heavy line - of - sight absorption and the observed x - ray spectrum is dominated by multi - temperature thermal emission associated with the nuclear starburst and the x - ray plume.   nevertheless the signature of the agn is present in the form of a neutral compton reflection component and a 6.4 kev fluorescent iron k@xmath3 line.   we conjecture that the site of the continuum reprocessing is the far wall of a highly inclined molecular torus, a geometry which is consistent with the presence of @xmath4 megamaser emission in this source.   the soft spectrum ( @xmath5 kev ) and limb - brightened appearance of the x - ray plume suggest an interpretation in terms of a mass - loaded superwind emanating from the nuclear starburst.   * key words : * galaxies : individual : ngc4945  galaxies : seyfert  x - rays : galaxies.    0  km  s^-1  mpc^-1    25d@xmath6 250.25 kev
electron beam induced current ( ebic ) is a powerful technique which measures the charge collection efficiency of photovoltaics with sub - micron spatial resolution.   the exciting electron beam results in a high generation rate density of electron - hole pairs, which may drive the system into nonlinear regimes.   an analytic model is presented which describes the ebic response when the _ total _ electron - hole pair generation rate exceeds the rate at which carriers are extracted by the photovoltaic cell, and charge accumulation and screening occur.   the model provides a simple estimate of the onset of the high injection regime in terms of the material resistivity and thickness, and provides a straightforward way to predict the ebic lineshape in the high injection regime.   the model is verified by comparing its predictions to numerical simulations in 1 and 2 dimensions.   features of the experimental data, such as the magnitude and position of maximum collection efficiency versus electron beam current, are consistent with the 3 dimensional model.
quantum state sharing is a protocol where perfect reconstruction of quantum states is achieved with incomplete or partial information in a multi - partite quantum network.   quantum state sharing allows for secure communication in a quantum network where partial information is lost or acquired by malicious parties.   this protocol utilizes entanglement for the secret state distribution, and a class of  quantum disentangling " protocols for the state reconstruction.   we demonstrate a quantum state sharing protocol in which a tripartite entangled state is used to encode and distribute a secret state to three players.   any two of these players can collaborate to reconstruct the secret state, whilst individual players obtain no information.   we investigate a number of quantum disentangling processes and experimentally demonstrate quantum state reconstruction using two of these protocols.   we experimentally measure a fidelity, averaged over all reconstruction permutations, of @xmath0.   a result achievable only by using quantum resources.
recent high - resolution infrared space missions have revealed supernova remnants ( snrs ) of diverse morphology in infrared ( ir ) dust emission that is often very different from their x - ray appearance.   the observed range of infrared - to - x - ray ( irx ) flux ratios of snrs are also wide. for a sample of 20 galactic snrs, we obtain their ir and x - ray properties and investigate the physical causes for such large differences.   we find that the observed irx flux ratios ( ) are related to the irx morphology, with snrs with the largest  showing anticorrelated irx morphology. by analyzing the relation of  to x - ray and ir parameters  , we show that the  of some snrs agree with theoretical ratios of snr shocks in which dust grains are heated and destroyed by collisions with plasma particles. for the majority of snrs,   however,  values are either significantly smaller or significantly larger than the theoretical ratios.   the latter snrs have relatively low dust temperatures.   we discuss how the natural and/or environmental properties of snrs could have affected the irx flux ratios and the irx morphology of these snrs.   we conclude that the snrs with largest  are probably located in dense environment and that their ir emission is from dust heated by shock radiation rather than by collisions.   our result suggests that the irx flux ratio, together with dust temperature, can be used to infer the nature of unresolved snrs in external galaxies.   = 1
the 2 - 10 kev continuum of agn is generally well represented by a single power law.   however, at smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the `` soft x - ray excess ''. until now this soft x - ray excess was attributed, either to reflection of the hard x - ray source by the accretion disk, or to the presence of an additional comptonizing medium, giving a steep spectrum.   an alternative solution proposed by gierli'nski and done ( 2004 ) is that a single power law well represents both the soft and the hard x - ray emission and the impression of the soft x - ray excess is due to absorption of a primary power law by a relativistic wind.   we examine the advantages and drawbacks of reflection versus absorption models, and we conclude that the observed spectra can be well modeled, either by absorption ( for a strong excess ), or by reflection ( for a weak excess ).   however the physical conditions required by the absorption models do not seem very realistic : we would prefer an `` hybrid model ''.     absorbed by a constant total pressure slab ( @xmath0, @xmath1, @xmath2, cgs units ).   the observed and computed spectra have been both divided by the observed power law of photon index @xmath3 over the 210 kev range.  , width=272 ]
the xinglong 2.16-m reflector is the first 2-meter class astronomical telescope in china.   it was jointly designed and built by the nanjing astronomical instruments factory ( naif ), beijing astronomical observatory ( now national astronomical observatories, chinese academy of sciences, naoc ) and institute of automation, chinese academy of sciences in 1989.   it is ritchey - chrtien ( r - c ) reflector on an english equatorial mount and the effective aperture is 2.16 meters.   it had been the largest optical telescope in china for @xmath0 years until the guoshoujing telescope ( also called large sky area multi - object fiber spectroscopic telescope, lamost ) and the lijiang 2.4-m telescope were built. at present, there are three main instruments on the cassegrain focus available : the beijing faint object spectrograph and camera ( bfosc ) for direct imaging and low resolution ( @xmath1 ) spectroscopy, the spectrograph made by optomechanics research inc.   ( omr ) for low resolution spectroscopy ( the spectral resolutions are similar to those of bfosc ) and the fiber - fed high resolution spectrograph ( hrs, @xmath2 ). the telescope is widely open to astronomers all over china as well as international astronomical observers.   each year there are more than 40 ongoing observing projects, including 6 - 8 key projects.   recently, some new techniques and instruments ( e.g., astro - frequency comb calibration system, polarimeter and adaptive optics ) have been or will be tested on the telescope to extend its observing abilities.
this article is concerned with the representation of curves by means of integral invariants.   in contrast to the classical differential invariants they have the advantage of being less sensitive with respect to noise. the integral invariant most common in use   is the circular integral invariant.   a major drawback of this curve descriptor, however, is the absence of any uniqueness result for this representation.   this article serves as a contribution towards closing this gap by showing that the circular integral invariant is injective in a neighbourhood of the circle.   in addition, we provide a stability estimate valid on this neighbourhood.   the proof is an application of riesz  schauder theory and the implicit function theorem in a banach space setting.   martin bauer    thomas fidler    markus grasmair
we present an energy - conserving multiple - relaxation - time finite difference lattice boltzmann model for compressible flows.   this model is based on a 16-discrete - velocity model.   the collision step is first calculated in the moment space and then mapped back to the velocity space.   the moment space and corresponding transformation matrix are constructed according to the group representation theory.   equilibria of the nonconserved moments are chosen according to the need of recovering compressible navier - stokes equations through the chapman - enskog expansion.   numerical experiments showed that compressible flows with strong shocks can be well simulated by the present model.   the used benchmark tests include ( i ) shock tubes, such as the sod, lax, colella explosion wave, collision of two strong shocks and a new shock tube with high mach number, ( ii ) regular and mach shock reflections, ( iii ) shock wave reaction on cylindrical bubble problems, and ( iv)couette flow.   the new model works for both low and high speeds compressible flows.   it contains more physical information and has better numerical stability and accuracy than its single - relaxation - time version.
we report results from monte carlo simulations of a thin film superconductor in a spherical geometry within the lowest landau level approximation. we observe the absence of a phase transition to a low temperature vortex solid phase with these boundary conditions ; the system remains in the vortex liquid phase for all accessible temperatures.   the correlation lengths are measured for phase coherence and density modulation.   both lengths display identical temperature dependences, with an asymptotic scaling form consistent with a continuous zero temperature transition.   this contrasts with the first order freezing transition which is seen in the alternative quasi - periodic boundary conditions. the high temperature perturbation theory and the ground states of the spherical system suggest that the thermodynamic limit of the spherical geometry is the same as that on the flat plane.   we discuss the advantages and drawbacks of simulations with different geometries, and compare with current experimental conclusions.   the effect of having a large scale inhomogeneity in the applied field is also considered.   epsf    2
we present the results of vlt - muse integral field spectroscopy of secco  1, a faint, star - forming stellar system recently discovered as the stellar counterpart of an ultra compact high velocity cloud ( hvc274.68 + 74.0 ), very likely residing within a substructure of the virgo cluster of galaxies.   we have obtained the radial velocity of a total of 38 individual compact sources identified as hii regions in the main and secondary body of the system, and derived the metallicity for 18 of them.   we provide the first direct demonstration that the two stellar bodies of secco  1 are physically associated and that their velocities match the hi velocities.   the metallicity is quite uniform over the whole system, with a dispersion lower than the uncertainty on individual metallicity estimates.   the mean abundance, @xmath0, is much higher than the typical values for local dwarf galaxies of similar stellar mass.   this strongly suggests that the secco  1 stars were born from a pre - enriched gas cloud, possibly stripped from a larger galaxy. using archival hst images we derive a total stellar mass of @xmath1 for secco  1, confirming that it has a very high hi to stellar mass ratio for a dwarf galaxy, m@xmath2/m@xmath3. the star formation rate, derived from the h@xmath4 flux is a factor of more than @xmath5 higher than in typical dwarf galaxies of similar luminosity.       ism : hii regions  galaxies : dwarf  galaxies : star formation
we consider a model system in which anomalous diffusion is generated by superposition of underlying linear modes with a broad range of relaxation times. in the language of gaussian polymers  , our model corresponds to rouse ( fourier ) modes whose friction coefficients scale as wavenumber to the power @xmath0.   a single ( tagged ) monomer then executes subdiffusion over a broad range of time scales, and its mean square displacement increases as @xmath1 with @xmath2. to demonstrate non - trivial aspects of the model  , we numerically study the absorption of the tagged particle in one dimension near an absorbing boundary or in the interval between two such boundaries.   we obtain absorption probability densities as a function of time, as well as the position - dependent distribution for unabsorbed particles, at several values of @xmath3.   each of these properties has features characterized by exponents that depend on @xmath3.   characteristic distributions found for different values of @xmath3 have similar qualitative features, but are not simply related quantitatively.   comparison of the motion of translocation coordinate of a polymer moving through a pore in a membrane with the diffusing tagged monomer with identical @xmath3 also reveals quantitative differences.
we review recent numerical work investigating the equilibrium phase diagram, and the dynamics, of the cholesteric blue phases. in equilibrium   numerical results confirm the predictions of the classic analytical theories, and extend them to incorporate different values of the elastic constants, or the effects of an applied electric field.   there is a striking increase in the stability of blue phase i in systems where the cholesteric undergoes helical sense inversion, and the anomalous electrostriction observed in this phase is reproduced. solving the equations of motion allows us to present results for the phase transition kinetics of blue phase i under dielectric or flexoelectric coupling to an applied electric field.   we also present simulations of the blue phases in a flow field, showing how the disclination network acts to oppose the flow.   the results are based on the landau - de gennes exapnsion of the liquid crystal free energy : that such a simple and elegant theory can predict such complex and subtle physical behaviour is remarkable.
in this paper, we give a distributed joint source channel coding scheme for arbitrary correlated sources for arbitrary point in the slepian - wolf rate region, and arbitrary link capacities using ldpc codes.   we consider the slepian - wolf setting of two sources and one destination, with one of the sources derived from the other source by some correlation model known at the decoder. distributed encoding and separate decoding is used for the two sources.   we also give a distributed source coding scheme when the source correlation has memory to achieve any point in the slepian - wolf rate achievable region. in this setting, we perform separate encoding but joint decoding.   distributed source coding, joint source - channel coding, ldpc codes, slepian - wolf.
spiral density wave theories demand that grand design spiral structure be bounded, at most, between the inner and outer lindblad resonances of the spiral pattern.   the corotation resonance lies between the outer and inner lindblad resonances.   the locations of the resonances are at radii whose ratios to each other are rather independent of the shape of the rotation curve. the measured ratio of outer to inner extent of spiral structure for a given spiral galaxy can be compared to the standard ratio of corotation to inner lindblad resonance radius. in the case that the measured ratio far exceeds the standard ratio, it is likely that the corotation resonance is within the bright optical disk.   studying such galaxies can teach us how the action of resonances sculpts the appearance of spiral disks.   this paper reports observations of 140 disk galaxies, leading to resonance ratio tests for 109 qualified spirals.   it lists candidates that have a good chance of having the corotation resonance radius within the bright optical disk.
bose - einstein condensation is a unique phase transition in that it is not driven by inter - particle interactions, but can theoretically occur in an ideal gas, purely as a consequence of quantum statistics.   this chapter addresses the question _ ` how is this ideal bose gas condensation modified in the presence of interactions between the particles?'_ this seemingly simple question turns out to be surprisingly difficult to answer. here   we outline the theoretical background to this question and discuss some recent measurements on ultracold atomic bose gases that have sought to provide some answers.
the barrel time - of - flight detector for the panda experiment at fair is foreseen as a scintillator tile ( scitil ) hodoscope based on several thousand small plastic scintillator tiles read - out with directly attached silicon photomultipliers ( sipms ).   the main tasks of the system are an accurate determination of the time origin of particle tracks to avoid event mixing at high collission rates, relative time - of - flight measurements as well as particle identification in the low momentum regime.   the main requirements are the use of a minimum material amount and a time resolution of @xmath0.   we have performed extensive optimization studies and prototype tests to prove the feasibility of the scitil design and finalize the r&d phase. in a 2.7gev / c proton beam at forschungszentrum jlich   a time resolution of about 80ps has been achieved using sipms from ketek and hamamatsu with an active area of @xmath1. employing the digital photon counter from philips   a time resolution of about 30ps has been reached.   scintillation detector, time - of - flight detector, particle identification, silicon photomultiplier ( sipm ), digital photon counter, panda experiment
quantum optics with quantum gases represents a new field, where the quantum nature of both light and ultracold matter plays equally important role  . only very recently this ultimate quantum limit of light - matter interaction became feasible experimentally.   in traditional quantum optics, the cold atoms are considered classically, whereas, in quantum atom optics, the light is used as an essentially classical axillary tool. on the one hand, the quantization of optical trapping potentials can significantly modify many - body dynamics of atoms, which is well - known only for classical potentials. on the other hand, atomic fluctuations can modify the properties of the scattered light.
in this third paper in a series presenting observations by the cassini ultraviolet imaging spectrometer ( uvis ) of the io plasma torus, we show remarkable, though subtle, spatio - temporal variations in torus properties. the io torus is found to exhibit significant, near - sinusoidal variations in ion composition as a function of azimuthal position.   the azimuthal variation in composition is such that the mixing ratio of is strongly correlated with the mixing ratio of and the equatorial electron density and strongly anti - correlated with the mixing ratios of both and and the equatorial electron temperature.   surprisingly, the azimuthal variation in ion composition is observed to have a period of 10.07 hours1.5% longer than the system iii rotation period of jupiter, yet 1.3% shorter than the system iv period defined by @xcite. although the amplitude of the azimuthal variation of and remained in the range of 25%, the amplitude of the and compositional variation ranged between 525% during the uvis observations.   furthermore, the amplitude of the azimuthal variations of and appears to be modulated by its location in system iii longitude, such that when the region of maximum mixing ratio ( minimum mixing ratio ) is aligned with a system iii longitude of @xmath0200@xmath1, the amplitude is a factor of @xmath04 greater than when the variation is anti - aligned.   this behavior can explain numerous, often apparently contradictory, observations of variations in the properties of the io plasma torus with the system iii and system iv coordinate systems.
we study traveling wave solutions of an equation for surface waves of moderate amplitude arising as a shallow water approximation of the euler equations for inviscid, incompressible and homogenous fluids.   we obtain solitary waves of elevation and depression, including a family of solitary waves with compact support, where the amplitude may increase or decrease with respect to the wave speed.   our approach is based on techniques from dynamical systems and relies on a reformulation of the evolution equation as an autonomous hamiltonian system which facilitates an explicit expression for bounded orbits in the phase plane to establish existence of the corresponding periodic and solitary traveling wave solutions.
inelastic neutron scattering experiments have been performed on lightly - doped la@xmath0sr@xmath1cuo@xmath2, which shows diagonal incommensurate spin correlations at low temperatures.   we previously reported that this crystal, with a single orthorhombic domain, exhibits the   hourglass " dispersion at low energies [ phys.   rev.   lett. 101, 197001 ( 2008 ) ]. in this paper  , we investigate in detail the energy evolution of the magnetic excitations up to 65 mev.   it is found that the anisotropic excitations at low energies, dispersing only along the spin modulation direction, crossover to an isotropic, conical dispersion that resembles spin waves in the parent compound la@xmath3cuo@xmath2.   the change from two - fold to full symmetry on crossing the waist of the hourglass reproduces behavior first identified in studies of underdoped.   we discuss the significance of these results.
we present new optical observations of the hh 111 herbig - haro jet using the gemini multi object spectrograph in its integral field unit mode.   eight fields of @xmath0 x @xmath1 have been positioned along and across the hh 111 jet, covering the spatial region from knot e to l in hh 111 ( namely, knots e, f, g, h, j, k and l ).   we present images and velocity channel maps for the  6300 + 6360, h@xmath2,  6548 + 6583 and  6716 + 6730 lines, as well as for the 6716/6730 line ratio.   we find that the hh  111 jet has an inner region with lower excitation and higher radial velocity, surrounded by a broader region of higher excitation and lower radial velocity. also, we find higher electron densities at lower radial velocities.   these results imply that the hh  111 jet has a fast, axial region with lower velocity shocks surrounded by a lower velocity sheath with higher velocity shocks.
a computational method based on a first - principles multiscale simulation has been used for calculating the optical response and the ablation threshold of an optical material irradiated with an ultrashort intense laser pulse.   the method employs maxwell s equations to describe laser pulse propagation and time - dependent density functional theory to describe the generation of conduction band electrons in an optical medium.   optical properties, such as reflectance and absorption, were investigated for laser intensities in the range @xmath0 to @xmath1 based on the theory of generation and spatial distribution of the conduction band electrons.   the method was applied to investigate the changes in the optical reflectance of @xmath2-quartz bulk, half - wavelength thin - film and quarter - wavelength thin - film and to estimate their ablation thresholds. despite the adiabatic local density approximation used in calculating the exchange  correlation potential,   the reflectance and the ablation threshold obtained from our method agree well with the previous theoretical and experimental results.   the method can be applied to estimate the ablation thresholds for optical materials in general.   the ablation threshold data can be used to design ultra - broadband high - damage - threshold coating structures.
in a recent paper @xcite we proposed a model for calculating cross - sections of various reaction products which arise from disintegration of projectile like fragment resulting from heavy ion collisions at intermediate or higher energy.   the model has three parts : ( 1 ) abrasion, ( 2 ) disintegration of the hot abraded projectile like fragment ( plf ) into nucleons and primary composites using a model of equilibrium statistical mechanics and ( 3 ) possible evaporation of hot primary composites.   it was assumed that the plf resulting from abrasion has one temperature @xmath0.   data suggested that while just one value of @xmath0 seemed adequate for most cross - sections calculations, it failed when dealing with very peripheral collisions.   we have now introduced a variable @xmath1 where @xmath2 is the impact parameter of the collision.   we argue there are data which not only show that @xmath0 must be a function of @xmath2 but, in addition, also point to an approximate value of @xmath0 for a given @xmath2.   we propose a very simple formula : @xmath3 where @xmath4 is the mass of the abraded plf and @xmath5 is the mass of the projectile ; @xmath6 and @xmath7 are constants.   using this model we compute cross - sections for several collisions and compare with data.
angular momentum is important concept in physics, and its phase space properties are important in various applications. in this work phase space analysis of the angular momentum is made from its classical definition, and by imposing uncertainty principle its quantum properties are obtained.   it is shown that kinetic energy operator is derived, but it has different interpretation of its parts than in the standard treatment.   rigid rotor is discussed and it is shown what is its phase space representation.   true rigid rotor is defined and also its phase space properties are discussed.
we discuss possible distortions of the ionization history of the universe in the model with small scale baryonic clouds.   the corresponding scales of the clouds are much smaller than the typical galactic mass scales.   these clouds are considered in a framework of the cosmological model with the isocurvature and adiabatic perturbations. in this model the baryonic clouds do not influence on the cosmic microwave background anisotropy formation directly as an additional sources of perturbations, but due to change of the kinetics of the hydrogen recombination.   we also study the corresponding distortions of the anisotropy and polarization power spectra in connection with the launched map and future planck missions.   cosmology : cosmic microwave background
we present a systematic overview of granular deposits composed of ellipsoidal particles with different particle shapes and size polydispersities.   we study the density and anisotropy of such deposits as functions of size polydispersity and two shape parameters that fully describe the shape of a general ellipsoid.   our results show that, while shape influences significantly the macroscopic properties of the deposits, polydispersity plays apparently a secondary role.   the density attains a maximum for a particular family of non - symmetrical ellipsoids, larger than the density observed for prolate or oblate ellipsoids. as for anisotropy measures,   the contact forces show are increasingly preferred along the vertical direction as the shape of the particles deviates for a sphere.   the deposits are constructed by means of an efficient molecular dynamics method, where the contact forces are efficiently and accurately computed.   the main results are discussed in the light of applications for porous media models and sedimentation processes.
epidemic outbreaks of new pathogens, or known pathogens in new populations, cause a great deal of fear because they are hard to predict. for theoretical models of disease spreading, on the other hand,   quantities characterizing the outbreak converge to deterministic functions of time.   our goal in this paper is to shed some light on this apparent discrepancy.   we measure the diversity of ( and, thus, the predictability of ) outbreak sizes and extinction times as functions of time given different scenarios of the amount of information available. under the assumption of perfect information  i.e.,  knowing the state of each individual with respect to the disease   the predictability decreases exponentially, or faster, with time.   the decay is slowest for intermediate values of the per - contact transmission probability. with a weaker assumption on the information available, assuming that we know only the fraction of currently infectious, recovered, or susceptible individuals, the predictability also decreases exponentially most of the time.   there are, however, some peculiar regions in this scenario where the predictability decreases. in other words, to predict its final size with a given accuracy, we would need increasingly more information about the outbreak.
i provide evidence that the 2d @xmath0 model for @xmath1 is equivalent to the @xmath2-invariant non - linear @xmath3-model in the continuum limit. to this end  , i mainly study particular versions of the models, to be called constraint models.   i prove that the constraint @xmath0 and @xmath2 models are equivalent for sufficiently weak coupling.   numerical results for the step - scaling function of the running coupling @xmath4 are presented.   the data confirm that the constraint @xmath2 model is in the same universality class as the @xmath2 model with standard action.   i show that the differences in the finite size scaling curves of @xmath0 and @xmath2 models observed by caracciolo et al. can be explained as a boundary effect.   it is concluded, in contrast to caracciolo et al.  , that @xmath0 and @xmath2 models share a unique universality class.    3ex    damtp 95 - 40    * *    @xmath2 and @xmath0 models    in two dimensions    damtp 95 - 40 july 1995
we investigate the stability of incompressible, exact, non - ideal magnetorotational ( mri ) modes against parasitic instabilities for a broad range of dissipation coefficients, relevant to astrophysical and laboratory environments.   this allows us to uncover the asymptotic behavior of the fastest parasites in terms of the elsasser number, @xmath0, when viscous effects are not important.   we calculate the fastest growing parasitic modes feeding off the mri and show that they correspond to kelvin - helmholtz instabilities for @xmath1 and tearing mode instabilities for @xmath2.   we study in detail the regime @xmath3 where both types of modes present comparable growth rates.   we conjecture about the asymptotic behavior of saturation based on the idea that the saturation level of the mri can be estimated by comparing growth rates ( or amplitudes ) of primary and secondary modes. in the ideal magnetohydrodynamic ( mhd )   limit, @xmath4, where kelvin - helmholtz modes dominate, these estimates lead to saturation levels for the stresses that are in rough agreement with current numerical simulations. for resistive mhd, @xmath5, the stresses produced by the mri primary modes, at the time when the fastest tearing modes have growth rates similar to their own, decay proportionally to the elsasser number.   this behavior seems consistent with numerical simulations of resistive mhd shearing boxes.
we consider a model of raman scattering for a two   dimensional @xmath0 heisenberg anti - ferromagnet which includes a _   dynamical _ spin  phonon interaction.   we observe a broadening of the line shape due to increased coupling with excited high  energy spin states.   our results are close to a model of random, static exchange interactions, first introduced in this context by haas _   et al. _ [ j. appl  . phys. * 75 *, 6340, ( 1994 ) ], which, when extended to large numbers of spins, explains experiments in the parent insulating compounds of high-@xmath1 superconductors.
a prominent continuum steepening is observed in quasar energy distributions near @xmath0.   we review possible interpretations for the origin of the so - called far - uv break, putting emphasis on those that favor the emergence of an upturn in the extreme - uv.
blue compact dwarf ( bcd ) galaxies are metal poor systems going through a major starburst that can not last for long.   we have identified galaxies which may be bcds during quiescence ( qbcd ), i.e., before the characteristic starburst sets in or when it has faded away.   these qbcd  galaxies are assumed to be like the bcd   host galaxies.   the sdss / dr6 database provides @xmath021500 qbcd  candidates.   we also select from sdss / dr6 a complete sample of bcd galaxies to serve as reference.   the properties of these two galaxy sets have been computed and compared.   the qbcd candidates are thirty times more abundant than the bcds, with their luminosity functions being very similar except for the scaling factor, and the expected luminosity dimming associated with the end of the starburst.   qbcds are redder than bcds, and they have larger h  ii region based oxygen abundance.   qbcds also have lower surface brightness.   the bcd candidates turn out to be the qbcd candidates with the largest specific star formation rate ( actually, with the largest @xmath1 equivalent width ).   one out of each three dwarf galaxies in the local universe may be a qbcd.   the properties of the selected bcds and qbcds are consistent with a single sequence in galactic evolution, with the quiescent phase lasting thirty times longer than the starburst phase.   the resulting time - averaged star formation rate is low enough to allow this cadence of bcd   qbcd phases during the hubble time.
the theory of scarring of eigenfunctions of classically chaotic systems by short periodic orbits is extended in several ways. the influence of short - time linear recurrences on correlations and fluctuations at long times is emphasized.   we include the contribution to scarring of nonlinear recurrences associated with homoclinic orbits, and treat the different scenarios of random and nonrandom long - time recurrences  . the importance of the local classical structure around the periodic orbit is emphasized, and it is shown for an optimal choice of test basis in phase space, scars must persist in the semiclassical limit.   the crucial role of symmetry is also discussed, which together with the nonlinear recurrences gives a much improved account of the actual strength of scars for given classical orbits and in individual wavefunctions.   quantitative measures of scarring are provided and comparisons are made with numerical data.
the determination of galaxy redshifts in _ james webb space telescope ( jwst ) s _ blank - field surveys will mostly rely on photometric estimates, based on the data provided by _   jwst s _ near - infrared camera ( nircam ) at @xmath0 and mid infrared instrument ( miri ) at @xmath1. in this work   we analyse the impact of choosing different combinations of nircam and miri broad - band filters ( f070w to f770w ), as well as having ancillary data at @xmath2, on the derived photometric redshifts ( @xmath3 ) of a total of 5921 real and simulated galaxies, with known input redshifts @xmath4.   we found that observations at @xmath5 are necessary to control the contamination of high-@xmath6 samples by low-@xmath6 interlopers.   adding miri ( f560w and f770w ) photometry to the nircam data mitigates the absence of ancillary observations at @xmath5 and improves the redshift estimation. at @xmath7  , accurate @xmath3 can be obtained with the nircam broad bands alone when @xmath8, but the @xmath3 quality significantly degrades at @xmath9.   adding miri photometry with one magnitude brighter depth than the nircam depth allows for a redshift recovery of @xmath10, depending on sed type, and its effect is particularly noteworthy for galaxies with nebular emission.   the vast majority of nircam galaxies with =29  ab  mag at @xmath7 will be detected with miri at @xmath11  mag if these sources are at least mildly evolved or have spectra with emission lines boosting
we report the discovery of a rich population of low mass stars in the young, massive star forming region n66/ngc346 in the small magellanic cloud, from deep v, i and h@xmath0 images taken with the hst / acs.   these stars have likely formed together with the ngc346 cluster, @xmath1 3 - 5 myr ago.   their magnitude and colors are those of pre - main sequence stars in the mass range 0.6 - 3 m@xmath2, mostly concentrated in the main cluster, but with secondary subclusters spread over a region across @xmath3 pc.   these subclusters appear to be spatially coincident with previously known knots of molecular gas identified in ground based and iso observations.   we show that n66/ngc346 is a complex region, being shaped by its massive stars, and the observations presented here represent a key step towards the understanding of how star formation occurred and has progressed in this low metallicity environment.
in this paper explore the relation between covariant and canonical approaches to quantum gravity and @xmath0 theory.   we will focus on the dynamical triangulation and spin - foam models, which have in common that they can be defined in terms of sums over space - time triangulations.   our aim is to show how we can recover these covariant models from a canonical framework by providing two regularisations of the projector onto the kernel of the hamiltonian constraint.   this link is important for the understanding of the dynamics of quantum gravity. in particular  , we will see how in the simplest dynamical triangulations model we can recover the hamiltonian constraint via our definition of the projector.   our discussion of spin - foam models will show how the elementary spin - network moves in loop quantum gravity, which were originally assumed to describe the hamiltonian constraint action, are in fact related to the time - evolution generated by the constraint.   we also show that the immirzi parameter is important for the understanding of a continuum limit of the theory.
in this paper we study two random analogues of the box - like self - affine attractors introduced by fraser, itself an extension of sierpiski carpets. we determine the almost sure box - counting dimension for the homogeneous random case ( @xmath0-variable random ), and give a sufficient condition for the almost sure box dimension to be the expectation of the box dimensions of the deterministic attractors.   furthermore we find the almost sure box - counting dimension of the random recursive model ( @xmath1-variable ), which includes affine fractal percolation.
the observation that type ia supernovae ( sne ia ) are fainter than expected given their red shifts has led to the conclusion that the expansion of the universe is accelerating.   the widely accepted hypothesis is that this acceleration is caused by a cosmological constant or, more generally, some dark energy field that pervades the universe. in this paper, we explore what, _ on their own _, the supernovae data tell us about this hypothesis.   we do so by answering the following question : can these data be explained with a model in which the strength of gravity varies on a cosmic timescale? we conclude that they can.   consequently, the supernovae data alone are insufficient to distinguish between a model with a cosmological constant and one in which @xmath0 varies. however, the varying - g models prove not to be viable when other data are taken into account.   this topic is an ideal one for investigation by an undergraduate physics major because the entire chain of reasoning from models to data analysis is well within the mathematical and conceptual sophistication of a motivated undergraduate.
we present results of a study of very low mass halo stars. using a sample of proper motion stars identified from plate material taken as part of the first and second palomar sky surveys, we measure the space density, metallicity distribution, and kinematics of the population ii m subdwarfs.   our overall luminosity function is in good agreement with previous analyses of the space density of nearby very - low - mass halo subdwarfs, and confirms the discrepancy between local analyses and the space densities inferred from deep hst starcounts.   we show for the first time that both the metallicity distribution and kinematics of late - type halo subdwarfs are consistent with those of their higher mass metal - poor counterparts. dividing our sample by abundance  , we find no evidence that the mass function of field halo stars is dependent upon metallicity.   we provide data for three nearby subdwarfs that may merit additional observations.
i discuss how a quantum annealer may be employed for an inference task of finding the likely lowest energy state for a system of qubits with uncertainty values for the state of individual qubits and clusters of qubits depending on the structure of the driver hamiltonian.   these calls to an annealer can be used as a computational primitive for hybrid computations. in particular,   such a computational primitive can be used quite naturally as a directed mutation engine for genetic algorithms.   i discuss how this can be done, as well as other ways in which such annealer calls can be applied to solving problems.   i further discuss the practicality of implementing such a protocol on real devices, and furthermore demonstrate that these methods are compatible with many of the current efforts by others to improve the performance of annealers, including the use of non - stoquastic drivers, synchronizing freeze times for individual bits, and belief propagation techniques which allow problems to be solved which do not fit on the hardware graph.   department of physics, durham university, south road, durham, uk
we describe simple linear time algorithms for coloring the squares of balanced and unbalanced quadtrees so that no two adjacent squares are given the same color.   if squares sharing sides are defined as adjacent, we color balanced quadtrees with three colors, and unbalanced quadtrees with four colors ; these results are both tight, as some quadtrees require this many colors.   if squares sharing corners are defined as adjacent, we color balanced or unbalanced quadtrees with six colors ; for some quadtrees, at least five colors are required.
we assume that the noncommutativity starts to be visible continuously from a scale @xmath0. according to this assumption  , a two - loop effective action is derived for noncommutative @xmath1 and @xmath2 theories from a wilsonian point of view.   we show that these effective theories are free of uv / ir mixing phenomena.   we also investigate the positivity constraint on coefficients of higher dimension operators present in the effective theory.   this constraint makes the low energy theory to be uv completion of a full theory.   finally, we discuss noncommutativity and extra dimensions. in our effective theories formulated on noncommutative extra dimensions,   if the campactification scale @xmath3 is less than the scale @xmath0, the theory will not suffer from uv / ir mixing.   effective field theory of a locally noncommutative space - time and extra dimensions    4em     * b.  mirza * and    1em    department of physics, isfahan university of technology, isfahan 84156 - 83111, iran
multi - photon states are widely applied in quantum information technology. by the methods presented in this paper, the structure of a multi - photon state in the form of multiple single photon qubit product   can be mapped to a single photon qudit, which could also be in separable product with other photons.   this makes the possible manipulation of such multi - photon states in the way of processing single photon states.   the optical realization of unknown qubit discrimination [ b. he, j. a. bergou, and y.- h.   ren, phys.   rev.   a 76, 032301 ( 2007 ) ] is simplified with the transformation methods.   another application is the construction of quantum logic gates, where the inverse transformations back to the input state spaces are also necessary.   we especially show that the modified setups to implement the transformations can realize the deterministic multi - control gates ( including toffoli gate ) operating directly on the products of single photon qubits.
we employ the gauge / gravity duality to study the jet quenching of light probes traversing a static yet anisotropic strongly coupled @xmath0 super yang - mills plasma.   we compute the stopping distance of an image jet induced by a massless source field, which is characterized by a massless particle falling along the null geodesic in the wkb approximation, in an anisotropic dual geometry introduced by mateos and trancancelli. at mid and large anisotropic regimes,   the stopping distances of a probe traveling in the anisotropic plasma along various orientations are suppressed compared to those in an isotropic plasma especially along the longitudinal direction at equal temperature. however, when fixing the entropy density, the anisotropic values of stopping distances near the transverse directions slightly surpass the isotropic values. in general, the jet quenching of light probes is increased by the anisotropic effect in a strongly coupled and equilibrium plasma.
the paper presents the group theory of best localized and symmetry - adapted wannier functions in a crystal of any given space group g or magnetic group m. provided that the calculated band structure of the considered material is given and that the symmetry of the bloch functions at all the points of symmetry in the brillouin zone is known, the paper details whether or not the bloch functions of particular energy bands can be unitarily transformed into best localized wannier functions symmetry - adapted to the space group g, to the magnetic group m, or to a subgroup of g or m. in this context, the paper considers usual as well as spin - dependent wannier functions, the latter representing the most general definition of wannier functions.   the presented group theory is a review of the theory published by one of the authors in several former papers and is independent of any physical model of magnetism or superconductivity.   however, it is suggested to interpret the special symmetry of the best localized wannier functions in the framework of a nonadiabatic extension of the heisenberg model, the nonadiabatic heisenberg model.   on the basis of the symmetry of the wannier functions, this model of strongly correlated localized electrons makes clear predictions whether or not the system can possess superconducting or magnetic eigenstates.
in this paper, we investigate the problem of graph list colouring in the on - line setting.   we provide several results on paintability of graphs in the model introduced by schauz  @xcite and zhu  @xcite.   we prove that the on - line version of ohba s conjecture is true in the class of planar graphs.   we also consider several alternate on - line list colouring models.
in this paper, we show that an interaction between dark matter and dark energy is in better agreement with the most recent large scale structure observations than the standard @xmath0cdm scenario.   the result presented by the boss - sdss collaboration measuring the baryon acoustic oscillations of the ly-@xmath1 forest from high - redshift quasars indicates a @xmath2 departure from the standard @xmath0cdm model.   this is the first time that the evolution of dark energy at high redshifts has been measured, and the current results can not be explained by simple generalizations of the cosmological constant. we show here that a simple phenomenological interaction in the dark sector provides a good explanation for this deviation, naturally accommodating the hubble parameter obtained by boss, @xmath3. by performing a global fit of the parameters with the inclusion of this new data set together with the _ planck _ data for the interacting model, we are able to show that some interacting models have constraints for @xmath4 and @xmath5 that are compatible with the ones obtained by the boss collaboration, showing a better concordance than @xmath0cdm.   a small positive coupling constant is obtained for those models, which also helps alleviating the coincidence problem.
using exact bethe ansatz ( ba ) solutions, we show that a spin - down fermion immersed into a fully polarized spin - up fermi sea with a weak attraction is dressed by the surrounding spin - up fermions to form the one - dimensional analog of a polaron.   as the attraction becomes strong, the spin - down fermion binds with one spin - up fermion to form a tightly bound molecule. throughout the whole interaction regime, a crossover from the polaron to a molecule state   is fully demonstrated through exact results of the excitation spectrum, the effective mass, binding energy and kinetic energy.   furthermore, a clear distinction between the polaron and molecule is conceived by the probability distribution, single particle reduced density matrix and density - density correlations, which are calculated directly from the bethe ansatz wave function.   such a polaron - molecule crossover presents a universal nature of an impurity immersed into a fermionic medium with an attraction in one dimension.
magnetic phase transition under hydrostatic pressure in tlcu@xmath0mg@xmath1cl@xmath2 was investigated by magnetization measurements.   the parent compound tlcucl@xmath2 is a coupled spin dimer system, which undergoes a pressure - induced quantum phase transition from a gapped ground state to an antiferromagnetic state at @xmath3 kbar due to the shrinkage of the gap. at ambient pressure,   the present doped system exhibits impurity - induced magnetic ordering at @xmath4 k. with increasing pressure, @xmath5 increases.   this is because the effective exchange interaction @xmath6 between unpaired spins is enhanced by the shrinkage of the gap. with a further increase in pressure,   the present system undergoes a phase transition to a uniform antiferromagnetic phase due to the closing of the triplet gap in the intact dimers.   the crossover from the impurity - induced ordered phase to the uniform antiferromagnetic phase occurs at @xmath7 kbar.
we report late - time observations of the radio afterglow of grb 030329.   the light curves show a clear achromatic flattening at 50 days after the explosion.   we interpret this flattening as resulting from the blast wave becoming trans - relativistic.   modeling of this transition enables us to make estimates of the energy content of the burst, regardless of the initial jet structure or the distribution of initial lorentz factors of the ejecta.   we find, in accordance with other events, that  is well - described by an explosion with total energy of a few times 10@xmath0 erg expanding into a circumburst medium with a density of order unity.
we present 7 eclipse timings of the low mass x - ray binary obtained with the usa experiment during 1999@xmath02000 as well as 122 eclipse timings obtained with rxte during 1996@xmath02000. according to our analysis, the mean orbital period   has _ increased _ by @xmath1 8 ms between the pre - rxte era ( 1985@xmath01990 ) and the rxte / usa era ( 1996@xmath02000 ).   this corresponds to an orbital period derivative of @xmath2 years.   however, neither a constant orbital period derivative nor any other simple ephemeris provides an acceptable fit to the data : individual timings of eclipse centers have residuals of up to 15 or more seconds away from our derived smooth ephemerides.   when we consider all published eclipse timing data including those presented here, a model that includes observational measurement error, cumulative period jitter, and underlying period evolution is found to be consistent with the timing data.   we discuss several physical mechanisms for lmxb orbital evolution in an effort to account for the change in orbital period and the observed intrinsic jitter in the mid - eclipse times.
in this paper, a family of multi - value cellular automaton ( ca ) associated with traffic flow is presented.   the family is obtained by extending the rule184 ca, which is an ultradiscrete analogue to the burgers equation.   ca models in the family show both metastable states and stop - and - go waves, which are often observed in real traffic flow.   metastable states in the models exist not only on a prominent part of a free phase but also in a congested phase.   = -1 cm = 23.5 cm
the timing and duration of exoplanet transits has a dependency on observer position due to parallax. in the case of an earth - bound observer with a 2 au baseline   the dependency is typically small and slightly beyond the limits of current timing precision capabilities.   however, it can become an important systematic effect in high - precision repeated transit measurements for long period systems due to its relationship to secular perspective acceleration phenomena. in this short paper   we evaluate the magnitude and characteristics of transit parallax in the case of exoplanets using simplified geometric examples.   we also discuss further implications of the effect, including its possible exploitation to provide immediate confirmation of planetary transits and/or unique constraints on orbital parameters and orientations.
in our recent investigation of the oosterhoff dichotomy in the multiple population paradigm @xcite, we have suggested that the rr lyrae variables in the oosterhoff groups i, ii, and iii globular clusters ( gcs ) are produced mostly by the first, second, and third generation stars ( g1, g2, and g3 ), respectively.   here we show, for the first time, that the observed dichotomies in the inner and outer halo gcs can be naturally reproduced when these models are extended to all metallicity regimes, while maintaining reasonable agreements in the horizontal - branch type versus  correlations. in order to achieve this,   however, specific star formation histories are required for the inner and outer halos. in the inner halo gcs,   the star formation commenced and ceased earlier with relatively short formation timescale between the subpopulations ( @xmath00.5 gyr ), while in the outer halo, the formation of g1 was delayed by @xmath00.8 gyr with more extended timescale between g1 and g2 ( @xmath01.4 gyr ).   this is consistent with the dual origin of the milky way halo. despite the difference in detail,   our models show that the oosterhoff period groups observed in both outer and inner halo gcs are all manifestations of the `` population - shift '' effect within the instability strip, for which the origin can be traced back to the two or three discrete episodes of star formation in gcs.
we study the effect of perpendicular single - ion anisotropy, @xmath0, on the ground - state structure and finite - temperature properties of a two - dimensional magnetic nanodot in presence of a dipolar interaction of strength @xmath1. by a simulated annealing monte carlo method  , we show that in the ground state a vortex core perpendicular to the nanodot plane emerges already in the range of moderate anisotropy values above a certain threshold level. in the giant - anisotropy regime   the vortex structure is superseded by a stripe domain structure with stripes of alternate domains perpendicular to the surface of the sample.   we have also observed an intermediate stage between the vortex and stripe structures, with satellite regions of tilted nonzero perpendicular magnetization around the core. at finite temperatures, at small @xmath2, we show by monte carlo simulations that there is a transition from the the in - plane vortex phase to the disordered phase characterized by a peak in the specific heat and the vanishing vortex order parameter. at stronger @xmath2  , we observe a discontinuous transition with a large latent heat from the in - plane vortex phase to perpendicular stripe ordering phase before a total disordering at higher temperatures. in the regime of perpendicular stripe domains,   namely with giant @xmath2, there is no phase transition at finite @xmath3 : the stripe domains are progressively disordered with increasing @xmath3.   finite - size effects are shown and discussed.
the naive calculation of black hole evaporation makes the thermal emission depend on the arbitrary high frequency behaviour of the theory where the theory is certainly wrong. using the sonic analog to black holes dumb holes   i show numerically that a change in the dispersion relation at high frequencies does not seem to alter the evaporation process, lending weight to the reality of the black hole evaporation process.   i also suggest a reason for the insensitivity of the process to high frequency regime.    #   1#2    figure # 1    _ # 2 _
in an interference network, joint power and admission control aims to support a maximum number of links at their specified signal to interference plus noise ratio ( sinr ) targets while using a minimum total transmission power. in our previous work, we formulated the joint control problem as a sparse @xmath0-minimization problem and relaxed it to a @xmath1-minimization problem. in this work  , we propose to approximate the @xmath0-optimization problem by a @xmath2 norm minimization problem where @xmath3, since intuitively @xmath2 norm will approximate @xmath4 norm better than @xmath5 norm.   we first show that the @xmath6-minimization problem is strongly np - hard and then derive a reformulation of it such that the well developed interior - point algorithms can be applied to solve it.   the solution to the @xmath6-minimization problem can efficiently guide the link s removals ( deflation ).   numerical simulations show the proposed heuristic outperforms the existing algorithms.
this paper gives an overview of recent research on the performance evaluation and design of carousel systems.   we discuss picking strategies for problems involving one carousel, consider the throughput of the system for problems involving two carousels, give an overview of related problems in this area, and present an extensive literature review.   emphasis has been given on future research directions in this area.   @xmath0 faculty of electrical engineering, mathematics and computer science, + department of applied mathematics, university of twente, + 7500 ae enschede, the netherlands.   @xmath1 eurandom and department of mathematics & computer science, + eindhoven university of technology, + p.o.   box 513, 5600 mb eindhoven, the netherlands.   + n.litvak@ewi.utwente.nl, m.vlasiou@tue.nl    * keywords : * order picking, carousels systems, travel time, throughput    * ams subject classification : * 90b05, 90b15
developing a theoretical framework to access quantum phases of itinerant bosons or fermions in two dimensions ( 2d ) that exhibit singular structure along surfaces in momentum space but have no quasi - particle description remains as a central challenge in the field of strongly correlated physics. in this paper   we propose that distinctive signatures of such 2d strongly correlated phases will be manifest in quasi - one - dimensional   @xmath0-leg ladder " systems.   characteristic of each parent 2d quantum liquid would be a precise pattern of 1d gapless modes on the @xmath0-leg ladder.   these signatures could be potentially exploited to approach the 2d phases from controlled numerical and analytical studies in quasi-1d. as a first step   we explore itinerant boson models with a frustrating ring exchange interaction on the 2-leg ladder, searching for signatures of the recently proposed two - dimensional d - wave correlated bose liquid ( dbl ) phase.   a combination of exact diagonalization, density matrix renormalization group, variational monte carlo, and bosonization analysis of a quasi-1d gauge theory, all provide compelling evidence for the existence of a new strong - coupling phase of bosons on the 2-leg ladder which can be understood as a descendant of the two - dimensional dbl.   we suggest several generalizations to quantum spin and electron hamiltonians on ladders which could likewise reveal fingerprints of such 2d non - fermi liquid phases.
in this paper, i revisit the constraints obtained by several authors ( reichart et al. 1999 ; eke et al.   1998 ; henry 2000 ) on the estimated values of @xmath0, @xmath1 and @xmath2 in the light of recent theoretical developments : 1 ) new theoretical mass functions ( sheth & tormen 1999, sheth, mo & tormen 2001, del popolo 2002b ) ; 2 ) a more accurate mass - temperature relation, also determined for arbitrary @xmath0 and @xmath3 ( del popolo 2002a ).   [ fig.   1 ]    firstly, using the quoted improvements, i re - derive an expression for the x - ray luminosity function ( xlf ), similarly to reichart et al.   ( 1999 ), and then i get some constraints to @xmath0 and @xmath1, by using the _ rosat _ bcs and emss samples and maximum - likelihood analysis  . then i re - derive the x - ray temperature function ( xtf ), similarly to henry ( 2000 ), re - obtaining the constraints on @xmath0, @xmath1, @xmath2. both in the case of the xlf and xtf, the changes in the mass function and m - t relation produces an increase in @xmath0 of @xmath4 and similar results in @xmath2 and @xmath1.
the `` square peg problem '' or `` inscribed square problem '' of toeplitz asks if every simple closed curve in the plane inscribes a ( non - degenerate ) square, in the sense that all four vertices of that square lie on the curve. by a variety of arguments of a `` homological '' nature, it is known that the answer to this question is positive if the curve is sufficiently regular.   the regularity hypotheses are needed to rule out the possibility of arbitrarily small squares that are inscribed or almost inscribed on the curve ; because of this, these arguments do not appear to be robust enough to handle arbitrarily rough curves.    in this paper   we augment the homological approach by introducing certain integrals associated to the curve.   this approach is able to give positive answers to the square peg problem in some new cases, for instance if the curve is the union of two lipschitz graphs @xmath0 \to { \mathbb{r}}$ ] that agree at the endpoints, and whose lipschitz constants are strictly less than one.   we also present some simpler variants of the square problem which seem particularly amenable to this integration approach, including a a periodic version of the problem that is not subject to the problem of arbitrarily small squares ( and remains open even for regular curves ), as well as an almost purely combinatorial conjecture regarding the sign patterns of sums @xmath1 for @xmath2 ranging in finite sets of real numbers.
following an old idea of fritz zwicky, we make an attempt to establish a `` universal '' mass function for astronomical objects on all scales.   the object classes considered are : solar system planets and small bodies, exoplanets, brown dwarfs, stars and stellar remnants, open and globular clusters, molecular clouds, galaxies, groups and clusters of galaxies. for comparison   we also include cdm halos taken from numerical simulations.   we show that the mass functions of individual object classes, when properly normalized, can indeed be concatenated to build a surprisingly continuous mass function of the universe, from @xmath0 ( sub - kilometer size asteroids ) up to @xmath1 ( rich clusters of galaxies ), covering 36 orders of magnitude in mass.   most individual mass functions roughly follow a power law of the form @xmath2. a notable exception   are planets and small bodies which seem to obey a flatter distribution.   cdm halos from high - resolution numerical simulations show a very similar relation, again of `` universal slope '' @xmath3, from clusters of galaxies all the way down to the planetary mass scale. on the scale of stars and star clusters   this is a remarkable coincidence, as the formation processes involved are thought to be totally different ( bottom - up gravitational clustering of dm halos versus top - down gravoturbulent fragmentation of gas clouds ).
we present a two - dimensional system which exhibits features of self - organized criticality.   the avalanches which occur on the surface of a pile of rice are found to exhibit finite size scaling in their probability distribution.   the critical exponents are @xmath0 = 1.21(2 ) for the avalanche size distribution and @xmath1 = 1.99(2 ) for the cut - off size.   furthermore the geometry of the avalanches is studied leading to a fractal dimension of the active sites of @xmath2 = 1.58(2 ). using a set of scaling relations  , we can calculate the roughness exponent @xmath3 = 0.41(3 ) and the dynamic exponent @xmath4 = 1.56(8 ).   this result is compared with that obtained from a power spectrum analysis of the surface roughness, which yields @xmath5 = 0.42(3 ) and @xmath6 = 1.5(1 ) in excellent agreement with those obtained from the scaling relations.   -1.5 cm 24.5 cm    2
luminescence properties of carbon nanotubes are strongly affected by exciton diffusion, which plays an important role in various nonradiative decay processes. here   we perform photoluminescence microscopy on hundreds of individual air - suspended carbon nanotubes to elucidate the interplay between exciton diffusion, end quenching, and exciton - exciton annihilation processes. a model derived from random - walk theory as well as monte carlo simulations   are utilized to analyze nanotube length dependence and excitation power dependence of emission intensity.   we have obtained the values of exciton diffusion length and absorption cross section for different chiralities, and diameter - dependent photoluminescence quantum yield have been observed.   the simulations have also revealed the nature of a one - dimensional coalescence process, and an analytical expression for the power dependence of emission intensity is given.
the entropy of the reissner - nrdstrom black hole is studied within the context of a brane - world scenario.   such a black hole is a solution of the einstein field equations on the brane, possessing a tidal charge which is a reflection of the extra dimension.   we use the modified dispersion relation to obtain the entropy of such brane - world black holes.   the resulting entropy differs from that of the standard bekenstein - hawking s and contains information on the extra dimension.    -2.7
systems with long range interactions present generically the formation of quasi - stationary long - lived non - equilibrium states.   these states relax to boltzmann equilibrium following a dynamics which is not well understood. in this paper   we study this process in two - dimensional inhomogeneous self - gravitating systems. using the chandrasekhar  or local  approximation we write a simple approximate kinetic equation for the relaxation process, obtaining a fokker   planck equation for the velocity distribution with explicit analytical diffusion coefficients.   performing molecular dynamics simulations and comparing them with the evolution predicted by the fokker   planck equation, we observe a good agreement with the model for all the duration of the relaxation, from the formation of the quasi - stationary state to thermal equilibrium.   we observe however an overestimate or underestimate of the relaxation rate of the particles with the slower or larger velocities respectively.   it is due to systematic errors in estimating the velocities of the particles at the moment of the collisions, inherent to the chandrasekhar approximation when applied to inhomogeneous systems.   theory and simulations give a scaling of the relaxation time proportional to the number of particles in the system.
we have used the ibis simulator to produce preliminary response matrices for the isgri and picsit detectors in order to help understanding their scientific performances before the calibration results are available.   the derived matrices, in a format compatible with the xspec spectral analysis package, have been tested by fitting simple models and then used to analyze simulations of astrophysical sources with more complex spectra.   
the paper discusses the influence of the external in - plane electric and magnetic field on the ground state spin phase diagram of selected monolayer graphene nanostructures.   the calculations are performed for triangular graphene nanoflakes with armchair edges as well as for short pieces of armchair graphene nanoribbons with zigzag terminations. the mean field approximation ( mfa )   is employed to solve the hubbard model.   the total spin for both classes of nanostructures is discussed as a function of external fields for various structure sizes, for charge neutrality conditions as well as for weak charge doping. the variety of nonzero spin states is found and their stability ranges are determined. for some structures,   the presence of antiferromagnetic orderings is predicted within the zero - spin phase.   the process of magnetization of nanoflakes with magnetic field at constant electric field is also investigated, showing opposite effect of electric field at low and at high magnetic fields.   graphene, graphene magnetism, graphene nanoflakes, metamagnetic transition, hubbard model, phase diagram
inclusive jet production will dominate the high @xmath0 final states at the lhc.  in this work   we try to estimate the up - to - date expectations, for high @xmath1 jets and their expected origin from the various parton - parton scattering processes. for these studies   we have used a standard parton distribution function ( pdf ) and simulated millions of events with the pythia8 event genertor.   the results are compared with simulations for center - of - mass energies of 0.9 tev, 2.36 tev, 7 tev and 14 tev corresponding to existing and future lhc runs.   we present some expectations for the relative cross sections of different quark flavours which indicates that eventually we might be able to measure the cross section for b - flavoured jets with reasonable accuracy up to an @xmath2 of a few tev.
high - precision analyses are presented for the production of scalar sleptons, selectrons and smuons in supersymmetric theories, at future @xmath0 and @xmath1 linear colliders.   threshold production can be exploited for measurements of the selectron and smuon masses, an essential ingredient for the reconstruction of the fundamental supersymmetric theory at high scales.   the production of selectrons in the continuum will allow us to determine the yukawa couplings in the selectron sector, scrutinizing the identity of the yukawa and gauge couplings, which is a basic consequence of supersymmetry.   the theoretical predictions are elaborated at the one - loop level in the continuum, while at threshold non - zero width effects and sommerfeld rescattering corrections are included.   the phenomenological analyses are performed for @xmath0 and @xmath1 linear colliders with energy up to about 1 tev and with high integrated luminosity up to 1 ab@xmath2 to cover the individual slepton channels separately with high precision.   desy 03111 + fermilab  pub03/314t +     +    _ @xmath3 fermi national accelerator laboratory, batavia, il 60510 - 500, usa _    @xmath4 desy theorie, notkestr.   85, d22603 hamburg, germany
we report results from a program of high - resolution spectral mapping of rotational h@xmath0 emission from bipolar planetary and pre - planetary nebulae.   long - slit spectra obtained with the noao phoenix near - infrared spectrometer allow us to probe the molecular kinematics of these nebulae at moderate spatial resolution.   we find strong evidence of a component of rotation in the equatorial h@xmath0 emission from the egg nebula ( rafgl 2688 ). in this nebula and   in the pre - planetary nebula rafgl 618, the h@xmath0 kinematics point to the recent emergence of high - velocity polar flows, which likely mark the fairly sudden terminations of the red giant phases of their central stars.   the classical bipolar planetary ngc 2346 displays distinct kinematic components, which we interpret as arising in the morphologically distinct equatorial and polar regions of the nebula.   the h@xmath0 rings observed in the phoenix position - velocity maps of this nebula support the hypothesis that ring - like planetaries that display h@xmath0 emission possess bipolar structure.
in this paper we study bielliptic curves of genus 3 defined over an algebraically closed field @xmath0 and the intersection of the moduli space @xmath1 of such curves with the hyperelliptic moduli @xmath2.   such intersection @xmath3 is an irreducible, 3-dimensional, rational algebraic variety.   we determine the equation of this space in terms of the @xmath4-invariants of binary octavics as defined in @xcite and find a birational parametrization of @xmath3.   we also compute all possible subloci of curves for all possible automorphism group @xmath5.   moreover, for every rational moduli point @xmath6, such that @xmath7, we give explicitly a rational model of the corresponding curve over its field of moduli in terms of the @xmath4-invariants.
we study the interlayer coherent incompressible phase in trilayer quantum hall systems ( tlqh ) at total filling factor @xmath0 from three approaches : mutual composite fermion ( mcf ), composite boson ( cb ) and wavefunction approach. just like in bilayer quantum hall system  , cb approach is superior than mcf approach in studying tlqh with broken symmetry.   the hall and hall drag resistivities are found to be quantized at @xmath1.   two neutral gapless modes with linear dispersion relations are identified and the ratio of the two velocities is close to @xmath2.   the novel excitation spectra are classified into two classes : charge neutral bosonic 2-body bound states and charge @xmath3 fermionic 3-body bound states. in general, there are two 2-body kosterlize - thouless ( kt ) transition temperatures and one 3-body kt transition.   the charge @xmath3 3-body fermionic bound states may be the main dissipation source of transport measurements.   the broken symmetry in terms of @xmath4 algebra is studied.   the structure of excitons and their flowing patterns are given.   the coupling between the two goldstone modes may lead to the broadening in the zero - bias peak in the interlayer correlated tunnelings of the tlqh.   several interesting features unique to tlqh are outlined. limitations of the cb approach are also pointed out.    2
we determine the phase diagrams of conservative diffusive contact processes by means of numerical simulations.   these models are versions of the ordinary diffusive single - creation, pair - creation and triplet - creation contact processes in which the particle number is conserved.   the transition between the frozen and active states was determined by studying the system in the subcritical regime and the nature of the transition, whether continuous or first order, was determined by looking at the fractal dimension of the critical cluster. for the single - creation model   the transition remains continuous for any diffusion rate.   for pair- and triplet - creation models, however, the transition becomes first order for high enough diffusion rate.   our results indicate that in the limit of infinite diffusion rate the jump in density equals 2/3 for the pair - creation model and 5/6 for the triplet - creation model.   pacs numbers : 05.50.ln, 05.50+q, 05.65.+b
the icecube neutrino observatory is a large cherenkov detector instrumenting @xmath0 of antarctic ice.   the detector can be used to search for signatures of particle physics beyond the standard model. here  , we describe the search for non - relativistic, magnetic monopoles as remnants of the gut ( * * g**rand * * u**nified * * t**heory ) era shortly after the big bang. depending on the underlying gauge group   these monopoles may catalyze the decay of nucleons via the rubakov - callan effect with a cross section suggested to be in the range of @xmath1 to @xmath2. in icecube,   the cherenkov light from nucleon decays along the monopole trajectory would produce a characteristic hit pattern.   this paper presents the results of an analysis of first data taken from may 2011 until may 2012 with a dedicated slow - particle trigger for deepcore, a subdetector of icecube.   a second analysis provides better sensitivity for the brightest non - relativistic monopoles using data taken from may 2009 until may 2010. in both analyses   no monopole signal was observed. for catalysis cross sections of @xmath3 the flux of non - relativistic gut monopoles   is constrained up to a level of @xmath4 at a 90% confidence level, which is three orders of magnitude below the parker bound.   the limits assume a dominant decay of the proton into a positron and a neutral pion.   these results improve the current best experimental limits by one to two orders of magnitude, for a wide range of assumed speeds and catalysis cross sections.   = 1
the new model of @xmath0 transitions in the medium based on unitary @xmath1-matrix is considered.   the time - dependence and corrections to the model are studied.   the lower limit on the free - space @xmath0 oscillation time @xmath2 is in the range @xmath3.   -0.6 in    11.30.fs ; 13.75.cs    keywords : diagram technique, infrared divergence, time - dependence    * e - mail : nazaruk@inr.ru
we observed electromagnetically induced transparency ( eit ) and dark fluorescence in a cascade three - level diatomic lithium system using optical - optical double resonance ( oodr ) spectroscopy. when a strong coupling laser couples the intermediate state @xmath0 to the upper state @xmath1 of @xmath2, the fluorescence from both @xmath3 and @xmath4 states was drastically reduced as the weak probe laser was tuned through the resonance transition between the ground state @xmath5 and the excited state @xmath0.   the strong coupling laser makes an optically thick medium transparent for the probe transition.   in addition, the fact that fluorescence from the upper state @xmath1 was also dark when both lasers were tuned at resonance implies that the molecules were trapped in the ground state.   we used density matrix methods to simulate the response of an open molecular three - level system to the action of a strong coupling field and a weak probe field.   the analytical solutions were obtained under the steady - state condition.   we have incorporated the magnetic sublevel ( m ) degeneracy of the rotational levels in the lineshape analysis and report @xmath6 dependent lineshape splitting.   the theoretical calculations are in excellent agreement with the observed fluorescence spectra.   we show that the coherence is remarkably preserved even when the coupling field was detuned far from the resonance.
the strategy of constraining the lepton flavor mixing from remnant cp symmetry is investigated in a rather general way.   the neutrino mass matrix generally admits four remnant cp transformations which can be derived from the measured lepton mixing matrix in the charged lepton diagonal basis.   conversely, the lepton mixing matrix can be reconstructed from the postulated remnant cp transformations.   all mixing angles and cp violating phases can be completely determined by the full set of remnant cp transformations or three of them.   when one or two remnant cp transformations are preserved, the resulting lepton mixing matrix would depend on three real parameters or one real parameter respectively in addition to the parameters characterizing the remnant cp, and the concrete form of the mixing matrix is presented.   the phenomenological predictions for the mixing parameters are discussed.   the conditions leading to vanishing or maximal dirac cp violation are studied.
decoherence is one of the main obstacles in long - distance quantum communication.   recently, the theoretical work of frwis and w. dr ( phys. rev  . lett. * 106 *, 110402 ( 2011 ) ) and the experiment of lu _ et al. _   ( nat. photon.   * 8 *, 364 ( 2014 ) ) both showed that the logic qubits entanglement say the concatenated greenberger - horne - zeilinger ( c - ghz ) state is more robust under decoherence. in this paper, we describe a protocol for bell - state analysis for this logic qubits entanglement.   this protocol can also be extended to the multipartite c - ghz state analysis. also, we discuss its application in the quantum teleportation of a unknown logic qubit and in the entanglement swapping of logic bell states. as   the logic qubits entanglement is more robust under decoherence, our protocol shows that it is possible to realize the long - distance quantum communication based on logic qubits entanglement.
in this paper, i address the oscillation probability of @xmath0(gev ) neutrinos of all active flavours produced inside the sun and detected at the earth.   flavours other than electron - type neutrinos may be produced, for example, by the annihilation of wimps which may be trapped inside the sun. in the gev energy regime,   matter effects are important both for the `` 13 '' system and the `` 12 '' system, and for different neutrino mass hierarchies.   a numerical scan of the multidimensional three - flavour parameter space is performed, `` inspired '' by the current experimental situation.   one important result is that, in the three - flavour oscillation case, @xmath1 for a significant portion of the parameter space, even if there is no @xmath2-violating phase in the mns matrix.   furthermore, @xmath3 has a significantly different behaviour from @xmath4, which may affect expectations for the number of events detected at large neutrino telescopes.   cern - th-2000 - 168 +   hep - ph/0006157 +.3 in    * the oscillation probability of gev solar neutrinos of all active species *    0.5 in    andr de gouva    0.1 in    _ cern - theory division + ch-1211 geneva 23, switzerland _  .2 in
repetitive spatio - temporal propagation patterns are encountered in fields as wide - ranging as climatology, social communication and network science. in neuroscience  , perfectly consistent repetitions of the same global propagation pattern are called a _ synfire pattern_. for any recording of sequences of discrete events ( in neuroscience terminology : sets of spike trains ) the questions arise how closely it resembles such a synfire pattern and which are the spike trains that lead / follow. here   we address these questions and introduce an algorithm built on two new indicators, termed _ spike - order _ and _ spike train order _, that define the _ synfire indicator _ value, which allows to sort multiple spike trains from leader to follower and to quantify the consistency of the temporal leader - follower relationships for both the original and the optimized sorting.   we demonstrate our new approach using artificially generated datasets before we apply it to analyze the consistency of propagation patterns in two real datasets from neuroscience ( giant depolarized potentials in mice slices ) and climatology ( el nio sea surface temperature recordings ).   the new algorithm is distinguished by conceptual and practical simplicity, low computational cost, as well as flexibility and universality.   ,   ,   ,
this is the third in a series of papers reporting on a large reverberation - mapping campaign aimed to study the properties of active galactic nuclei ( agns ) with high accretion rates.   we present new results on the variability of the optical fe ii  emission lines in 10 agns observed by the yunnan observatory 2.4 m telescope during 20122013.   we detect statistically significant time lags, relative to the agn continuum, in nine of the sources.   this accurate measurement is achieved by using a sophisticated spectral fitting scheme that allows for apparent flux variations of the host galaxy, and several narrow lines, due to the changing observing conditions.   six of the newly detected lags are indistinguishable from the h@xmath0  lags measured in the same sources.   two are significantly longer and one is slightly shorter. combining with fe ii  lags reported in previous studies  , we find a fe ii  radius  luminosity relationship similar to the one for h@xmath0, although our sample by itself shows no clear correlation.   the results support the idea that fe ii  emission lines originate in photoionized gas which, for the majority of the newly reported objects, is indistinguishable from the h@xmath0-emitting gas.   we also present a tentative correlation between the lag and intensity of fe ii  and h@xmath0  and comment on its possible origin.
we present results from a monte carlo investigation of a simple bilayer model with geometrically frustrated interactions similar to those found in the mixed layer pnictide oxides @xmath0 our model is composed of two inequivalent square lattices with nearest neighbor intra- and interlayer interactions.   we find a ground state composed of two independent nel ordered layers when the interlayer exchange is an order of magnitude weaker than the intralayer exchange, as suggested by experiment.   we observe this result independent of the number of layers in our model.   we find evidence for local orthogonal order between the layers, but it occurs in regions of parameter space that are not experimentally realized. we conclude that frustration caused by nearest neighbor interactions in the mixed layer pnictide oxides is not sufficient to explain the long  range orthogonal order that is observed experimentally, and that it is likely that other terms ( e.g., local anisotropies ) in the hamiltonian are required to explain the magnetic behavior.
the theoretical procedure of supersymmetric quantum mechanics ( sqm ) is adopted to study the resonance states of the unbound nucleus @xmath0be.   we have been able to reproduce the unbound state energies without any modification of our constructed density dependent m3y ( ddm3y ) microscopic potential.   our procedure confirmed the existence of 5/2 + state and also reproduced the experimentally predicted unbound resonance energy of 1.8 mev.
the spectral density for vector vibrations in the f.c.c.   lattice with force - constant disorder is analysed within the coherent potential approximation.   the phase diagram showing the weak- and strong - scattering regimes is presented and compared with that for electrons. the weak - scattering regime for external long - wavelength vibrational plane waves   is shown to be due to sum - rule correlations in the dynamical matrix.   a secondary peak below the brillouin peak for sufficiently large wavevectors is found for the lattice models.   the results obtained are supported by precise numerical solutions.   * u *    * h *
the rather wide - spread belief that cosmological expansion of a flat 3d  space ( with spatial curvature @xmath0 ) can not be observationally distinguished from a kinematics of galaxies moving in a flat and non - expanding space is erroneous.   we suggest that the error may have its source in a non relativistic intuition that imagines the universe not as a _ spacetime _ but separates space from time and pictures the cosmological expansion as space evolving in time. the physical reality, however, is fundamentally different  the expanding universe is _ necessarily _ a curved spacetime.   we show here that the fact that the _ spacetime _ is curved implies that the interpretation of the observed cosmological redshift as being due to the expansion of the cosmological 3d  space is observationally verifiable.   thus it is impossible to mimic the true cosmological redshift by a doppler effect caused by motion of galaxies in a non - expanding 3d - space, flat or curved.   we summarize our points in simple spacetime diagrams that illustrate a gedanken experiment distinguishing between expansion of space and pure kinematics.   we also provide all relevant mathematics. none of the previously published discussions of the issue, including a recent popular scientific american article @xcite, offered a similarly clear way out of the confusion.
a deep learning approach has been proposed recently to derive speaker identifies ( d - vector ) by a deep neural network ( dnn ).   this approach has been applied to text - dependent speaker recognition tasks and shows reasonable performance gains when combined with the conventional i - vector approach. although promising, the existing d - vector implementation still can not compete with the i - vector baseline.   this paper presents two improvements for the deep learning approach : a phone - dependent dnn structure to normalize phone variation, and a new scoring approach based on dynamic time warping ( dtw ).   experiments on a text - dependent speaker recognition task demonstrated that the proposed methods can provide considerable performance improvement over the existing d - vector implementation.    * index terms * : d - vector, time dynamic warping, speaker recognition
coupling of plasmons in graphene at terahertz ( thz ) frequencies with surface plasmons in a heavily - doped substrate is studied theoretically.   we reveal that a huge scattering rate may completely damp out the plasmons, so that proper choices of material and geometrical parameters are essential to suppress the coupling effect and to obtain the minimum damping rate in graphene.   even with the doping concentration @xmath0 @xmath1 and the thickness of the dielectric layer between graphene and the substrate @xmath2 nm, which are typical values in real graphene samples with a heavily - doped substrate, the increase in the damping rate is not negligible in comparison with the acoustic - phonon - limited damping rate.   dependence of the damping rate on wavenumber, thicknesses of graphene - to - substrate and gate - to - graphene separation, substrate doping concentration, and dielectric constants of surrounding materials are investigated.   it is shown that the damping rate can be much reduced by the gate screening, which suppresses the field spread of the graphene plasmons into the substrate.
galaxies and massive black holes ( bhs ) presumably grow via galactic merging events and subsequent bh coalescence. as a case study  , we investigate the merging event between the andromeda galaxy ( m31 ) and a satellite galaxy.   we compute the expected observational appearance of the massive bh that was at the center of the satellite galaxy prior to the merger, and is currently wandering in the m31 halo.   we demonstrate that a radiatively inefficient accretion flow with a bolometric luminosity of a few tens of solar luminosities develops when hoyle - lyttleton accretion onto the bh is assumed.   we compute the associated broadband spectrum and show that the radio band ( observable with evla, alma and ska ) is the best frequency range to detect the emission.   we also evaluate the mass and the luminosity of the stars bound by the wandering bh and find that such a star cluster is sufficiently luminous that it could correspond to one of the star clusters found by the pandas survey. the discovery of a relic massive bh wandering in a galactic halo will provide a direct means to investigate in detail the coevolution of galaxies and bhs.   it also means a new population of bhs ( off - center massive bhs ), and offers targets for clean bh imaging that avoids strong interstellar scattering in the center of galaxies.
i discuss double - diffractive ( double - elastic ) production of the @xmath0 and @xmath1 mesons in the @xmath2 reaction within the formalism of unintegrated gluon distribution functions ( ugdf ).   the contribution of @xmath3 fusion is estimated.   the distributions in the feynman @xmath4 ( or rapidity ), transferred four - momenta squared between initial and final protons ( @xmath5, @xmath6 ) and azimuthal angle difference between outgoing protons ( @xmath7 ) are calculated and discussed.   the results are compared with the wa102 data.   predictions at higher energies are presented.
a short review on theoretical implications of non - thermal emission ( radio, extreme ultraviolet, high energy x - ray ) from the intra - cluster medium is given.   the origin of cluster radio halos and cluster radio relics is discussed within the framework of a network of processes producing a non - thermal electron population.   emphasis is given to the role of old, remnant, presently invisible relativistic plasma released by former radio galaxies.
cloud radio access network ( c - ran ) is a promising architecture for unprecedented capacity enhancement in next - generation wireless networks thanks to the centralization and virtualization of base station processing.   however, centralized signal processing in c - rans involves high computational complexity that quickly becomes unaffordable when the network grows to a huge size.   this paper endeavours to design a _ scalable _ uplink signal detection algorithm, in the sense that the complexity per unit network area remains constant when the network size grows. to this end  , we formulate the signal detection in c - ran as an inference problem over a bipartite random geometric graph. by passing messages among neighboring nodes, message passing ( a.k.a.   belief propagation ) provides an efficient way to solve the inference problem over a sparse graph.   however, the traditional message - passing algorithm is not guaranteed to converge, because the corresponding bipartite random geometric graph is locally dense and contains many short loops. as a major contribution of this paper,   we propose a randomized gaussian message passing ( rgmp ) algorithm to improve the convergence. instead of exchanging messages simultaneously or in a fixed order, we propose to exchange messages asynchronously in a random order.   numerical results show that the proposed rgmp algorithm has significantly better convergence performance than conventional message passing.   the randomness of the message update schedule also simplifies the analysis, and allows the derivation of the convergence conditions for the rgmp algorithm.   cloud - ran ; signal processing ; message passing ; belief propagation
a simple derivation of the optimal state estimation of a quantum bit was obtained by using the no - signaling principle. in particular, the no - signaling principle determines a unique form of the guessing probability independently of figures of merit, such as the fidelity or information gain.   this proves that the optimal estimation for a quantum bit can be achieved by the same measurement for almost all figures of merit.    0
we determine numerically the steady state spectrum for kelvin waves on a superfluid @xmath0he vortex that is driven by shaking its endpoints and damped by mutual friction.   the resulting spectrum depends very weakly on temperature and is almost independent of the drive amplitude.   surprisingly there seems to be no high @xmath1 cutoff, determined by the mutual friction even when the mutual friction is large.   this is likely due to spatially sharply peaked drive.   we also determine the power dissipated due to mutual friction, as a function of the number of kelvin modes present in the system, using different kelvin spectra.
the wavelet transform modulus maxima ( wtmm ) used in the singularity analysis of one fractal function is extended to study the fractal correlation of two multifractal functions.   the technique is developed in the framework of joint partition function analysis ( jpfa ) proposed by meneveau et al.    and is shown to be equally effective.   in addition, we show that another leading approach developed for the same purpose, namely, relative multifractal analysis, can be considered as a special case of jpfa at a particular parameter setting.   18 true pt    _1 h@xmath0lder
we have designed, implemented and tested a time - to - digital converter core in a low - cost spartan-6 fpga.   our design exploits the finite propagation speed in carry chains to realize a delay line in which the propagation distance of the incoming signal s edges is measured using hundreds of taps.   this technique enables the core to reach a precision far better than the minimum switching period of the fpga flip - flops. to compensate for process, voltage and temperature ( pvt ) effects  , our design uses a combination of two techniques : startup calibration and online calibration.   the startup calibration uses a statistical method to estimate the delay between the taps of the delay line and helps eliminate the effect of process variations.   the online calibration, which takes place without disruption of the core s operation, uses a ring oscillator whose frequency instability is measured and used to compensate for subsequent voltage and temperature effects on the delay line.   our tests show that our design reaches a precision of @xmath0 ps rms over a temperature range of 37c to 48c.    [   types and design styles ]
supersymmetric models with broken @xmath0-parity provide mechanisms that allow to generate majorana neutrino masses and magnetic moments through virtual particle - sparticle loops.   this constitutes an attractive alternative to the see - saw mechanism. in this paper   we present a  detailed calculation of the transition magnetic moments of a  majorana neutrino in gauge mediated supersymmetry breaking mssm without @xmath0-parity.   we base our analysis on the renormalization group evolution of the mssm parameters, which are unified at the gut scale.
using one - dimensional spin-1/2 systems as prototypes of quantum many - body systems, we study the emergence of quantum chaos. the main purpose of this work is to answer the following question : how does the spin - orbit interaction, as a pure quantum interaction, may lead to the onset of quantum chaos?   we consider three integrable spin-1/2 systems : the ising, the xx, and the xxz limits, and analyze whether quantum chaos develops or not after the addition of the dzyaloshinskii - moriya interaction.   we find that, depending on the strength of the anisotropy parameter, the answer is positive for the xxz and ising models, while no such evidence is observed for the xx model.   we also discuss the relationship between quantum chaos and thermalization.   +   + * the main purpose of this work is to answer this question : how the spin - orbit interaction as a pure quantum interaction may develop a quantum chaos which has no classical counterpart?.   the result can be summarized as follows : + 1- ising chain with added dzyaloshinskii - moriya ( dm ) interaction is chaotic.   + 2- xx chain with added dm interaction does not show a chaotic features.   + 3- xxz chain with added dm interaction is chaotic. *
it is explained why and how the fireball created in ultrarelativistic nuclear collisions can fragment when passing the phase transition.   it can happen at the first - order phase transition but is not excluded even at high collision energies where the smooth crossover is present.   two potential observables sensitive to the appearance of fragmentation are reviewed : event - by - event changes of rapidity distributions and proton correlation in relative rapidity.
we investigate the conductance statistics of a quantum - chaotic dot  a normal - metal grain  with a superconducting lead attached to it.   the cases of one and two normal leads additionally attached to the dot are studied.   for these two configurations the complete distribution of the conductance is calculated, within the framework of random matrix theory, as a function of the transparency parameter of the schottky barrier formed at the interface of the normal - metal and superconducting regions.   our predictions are verified by numerical simulations.
we consider a two - layer heisenberg antiferromagnet which can be either in the nel - ordered or in the disordered phase at @xmath0, depending on the ratio of the intra- and interlayer exchange constants.   we reduce the problem to an interacting bose - gas and study the sublattice magnetization and the transverse susceptibility in the ordered phase, and the spectrum of quasiparticle excitations in both phases.   we compare the results with the spin - wave theory and argue that the longitudinal spin fluctuations, which are not included in the spin - wave description, are small at vanishing coupling between the layers, but increase as the system approaches the transition point.   we also compute the uniform susceptibility at the critical point to order @xmath1, and show that the corrections to scaling are numerically small, and the linear behavior of @xmath2 extends to high temperatures.   this is consistent with the results of the recent monte - carlo simulations by sandvik and scalapino.
we have studied the exotic superfluid phases of degenerated fermi gases with spin - orbit coupling in a mixed dimensional system, where the motion of atoms are free in the @xmath0-direction and the tunneling between nearest tubes in the @xmath1-direction is permitted. using the mean - field method  , we obtain the phase diagrams of the system during the dimensional crossover between quasi one dimension to quasi two dimension.   we find the existence of the topological state and majorana edge mode in the weak tunneling case, and a rich phase diagram including two kinds of nodal superfluid phase and gapped superfluid phase in the opposite case.   our results show that topological pairing is favoured in quasi one dimension while nodal pairing state is favoured in quasi two dimension.
a new _ xmm - newton  _ observation has made possible a detailed study of both lobes of the radio galaxy pictor a. their x - ray emission is of non thermal origin and due to inverse compton scattering of the microwave background photons by relativistic electrons in the lobes, as previously found. in both lobes, the equipartition magnetic field ( _ b@xmath0  _ ) is bigger than the inverse compton value ( _ b@xmath1  _ ), calculated from the radio and x - ray flux ratio. the _ b@xmath0   _ /_b@xmath1  _ ratio never gets below 2, in spite of the large number of reasonable assumptions tested to calculate _ b@xmath0  _, suggesting a lobe energetic dominated by particles.   the x - ray data quality is good enough to allow a spatially resolved analysis.   our study shows that _ b@xmath1  _ varies through the lobes.   it appears to increase behind the hot spots. on the contrary,   a rather uniform distribution of the particles is observed. as a consequence  , the radio flux density variation along the lobes appears to be mainly driven by magnetic field changes.
different mechanisms believed to be responsible for the generation of bursts in hydrodynamical systems are reviewed and a new mechanism capable of generating regular or irregular bursts of large dynamic range near threshold is described.   the new mechanism is present in the interaction between oscillatory modes of odd and even parity in systems of large but finite aspect ratio, and provides an explanation for the bursting behavior observed in binary fluid convection.   additional applications of the new mechanism are proposed. +
in energy harvesting ( eh ) network, the energy storage devices ( i.e., batteries ) are usually not perfect. in this paper, we consider a practical battery model with finite battery capacity, energy ( dis-)charging loss, and energy dissipation.   taking into account such battery imperfections, we rely on the lyapunov optimization technique to develop a stochastic online control scheme that aims to maximize the utility of data rates for eh multi - hop wireless networks.   it is established that the proposed algorithm can provide a feasible and efficient data admission, power allocation, routing and scheduling solution, without requiring any statistical knowledge of the stochastic channel, data - traffic, and eh processes.   numerical results demonstrate the merit of the proposed scheme.   stochastic optimization, energy harvesting, battery imperfections, wireless networks.
despite extensive work on the interplay between traffic dynamics and epidemic spreading, the control of epidemic spreading by routing strategies has not received adequate attention. in this paper  , we study the impact of efficient routing protocol on epidemic spreading. in the case of infinite node - delivery capacity, where the traffic is free of congestion  , we find that that there exists optimal values of routing parameter, leading to the maximal epidemic threshold.   this means that epidemic spreading can be effectively controlled by fine tuning the routing scheme.   moreover, we find that an increase in the average network connectivity and the emergence of traffic congestion can suppress the epidemic outbreak.
we test the finite density algorithm in the canonical ensemble which combines the hmc update with the accept / reject step according to the ratio of the fermion number projected determinant to the unprojected one as a way of avoiding the determinant fluctuation problem.   we report our preliminary results on the polyakov loop in different baryon number sectors which exhibit deconfinement transitions on small lattices.   the largest density we obtain around @xmath0 is an order of magnitude larger than that of nuclear matter. from the conserved vector current  , we calculate the quark number and verify that the mixing of different baryon sectors is small.
spin - dependent conductance across a manganate - barrier - manganate junction has recently been demonstrated.   the junction is a la@xmath0sr@xmath1mno@xmath2-srtio@xmath2-la@xmath0 sr@xmath1mno@xmath2 trilayer device supporting current - perpendicular transport.   large magnetoresistance of up to a factor of five change was observed in these junctions at 4.2k in a relatively low field of the order of 100 oe.   temperature and bias dependent studies revealed a complex junction interface structure whose materials physics has yet to be understood.   epsf.sty    
we report details of single crystal growth of stoichiometric bismuthide ptbi@xmath0 whose structure consists of alternate stacking of pt layer sandwiched by bi bilayer along the @xmath1-axis.   the compound crystallizes in space group p-3 with a hexagonal unit cell of @xmath2=@xmath3=6.553@xmath4, @xmath1=6.165@xmath4.   the magnetization data show opposite sign for fields parallel and perpendicular to the pt layers, respectively.   the @xmath5-dependent resistivity is typical of a metal and the magnetic response shows clear two types of charge carriers and the validity of the semi - classical kohler s rule.   its physical properties was discussed in comparison with recently proposed topological superconductor @xmath6-pdbi@xmath0.
we report on the growth of domains of standing waves in electroconvection in a nematic liquid crystal.   an ac voltage is applied to the system, forming an initial state that consists of travelling striped patterns with two different wavenumbers, zig and zag rolls.   the standing waves are generated by suddenly applying a periodic modulation of the amplitude of the applied voltage that is approximately resonant with the travelling frequency of the pattern. by varying the modulation frequency, we are able to vary the steady - state, average wavenumber.   we characterize the growth by measuring the structure factor for the pattern, the amplitude of the pattern, and the domain - wall length.   an interesting feature of the growth is that the evolution of the domain - wall length is strongly affected by changing the selected wavenumber ; whereas, the evolution of the structure factor is less sensitive to such changes.
we use sdss spectra and optical to far - infrared photometry for a sample of 31 felobal qsos to study the relationship between the agn - driven outflows, and obscured star formation in their host galaxies.   we find that felobal qsos invariably have ir luminosities exceeding @xmath0l@xmath1.   the agn supplies 75% of the total ir emission, on average, but with a range from 20% to 100@xmath2.   we find a clear anticorrelation between the strength of the agn - driven outflows and the contribution from star formation to the total ir luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows.   moreover, we find no evidence that this effect is driven by the ir luminosity of the agn.   we conclude that radiatively driven outflows from agn act to curtail obscured star formation in the host galaxies of reddened qsos to less than @xmath3 of the total ir luminosity.   this is the most direct evidence yet obtained for ` quasar mode'agn feedback.
we utilize a complete sample of rr lyrae stars discovered by the quest survey using light curves to design selection criteria based on sdss colors.   thanks to the sensitivity of the @xmath0 color to surface gravity and of @xmath1 color to effective temperature, and to the small photometric errors ( 0.02 mag ) delivered by sdss, rr lyrae stars can be efficiently and robustly recognized even with single - epoch data. in a 100% complete color - selected sample, the selection efficiency ( the fraction of rr lyrae stars in the candidate sample ) is 6%, and, by adjusting color cuts, it can be increased to 10% with a completeness of 80%, and to 60% with 28% completeness.   such color selection produces samples that are sufficiently clean for statistical studies of the milky way s halo substructure, and we utilize it to select 3,643 candidate rr lyrae stars from sdss data release 1.   we demonstrate that this sample recovers known clumps of rr lyrae stars associated with the sgr dwarf tidal tail, and pal 5 globular cluster, and use it to constrain the halo substructure away from the sgr dwarf tidal tail.   these results suggest that it will be possible to study the halo substructure out to @xmath270 kpc from the galactic center in the entire area imaged by the sdss, and not only in the multiply observed regions.   # 1@xmath3 # 1@xmath4 # 1    @xmath5    # 1 ( comment : # 1 )
there has been great interest in finding sets of @xmath0 mutually unbiased bases which are compatible with a given space @xmath1, specially in physics due to their interesting applications in quantum information theory.   several general results have been obtained so far, but surprising results may occur for definite @xmath2-values.   one such case that has remained an open question ( the simplest case ) is the one regarding the existence of @xmath3 mutually orthogonal bases for @xmath4. in the present work we introduce a new approach to the problem by translating it into an optimization procedure for a given pair @xmath2.
we formulate in a systematic manner the coherent state approach and apply it to study aharonov - bohm effect in the field theory context. within this approach  , we verify that the scattering amplitude is ultraviolet finite.   also, we prove that introduction of a quartic self - interaction for the scalar field allows to obtain a smooth commutative limit.
for some years now, we have been gathering optical spectra of da white dwarfs in an effort to study and define the empirical zz ceti instability strip.   however, we have recently expanded this survey to include all the da white dwarfs in the mccook & sion catalog down to a limiting visual magnitude of @xmath0=17.5.   we present here a spectroscopic analysis of over 1000 da white dwarfs from this ongoing survey.   we have several specific areas of interest most notably the hot dao white dwarfs, the zz ceti instability strip, and the da+dm binary systems.   furthermore, we present a comparison of the ensemble properties of our sample with those of other large surveys of da white dwarfs, paying particular attention to the distribution of mass as a function of effective temperature.
the galaxies m82, ngc 253, ngc 1068, and ngc 4945 have been detected in @xmath0-rays by _   fermi_. previously, we developed and tested a model for cosmic ray interactions in the starburst galaxy m82.   now, we aim to explore the differences between starburst and active galactic nuclei ( agn ) environments by applying our self - consistent model to the starburst galaxy ngc 253 and the seyfert galaxy ngc 1068. assuming constant cosmic - ray acceleration efficiency by supernova remnants with milky - way parameters, we calculate the cosmic - ray proton and primary and secondary electron / positron populations, predict the radio and @xmath0-ray spectra, and compare with published measurements.   we find that our models easily fits the observed @xmath0-ray spectrum for ngc 253 while constraining the cosmic ray source spectral index and acceleration efficiency.   however, we encountered difficultly modeling the observed radio data and constraining the speed of the galactic wind and the magnetic field strength, unless the gas mass is less than currently preferred values  . additionally, our starburst model consistently underestimates the observed @xmath0-ray flux and overestimates the radio flux for ngc 1068 ; these issues would be resolved if the agn is the primary source of @xmath0-rays.   we discuss the implications of these results and make predictions for the neutrino fluxes for both galaxies.
the fan observatory bench optical spectrograph ( fobos ) is intended for single - object optical spectroscopy at moderate resolution ( @xmath0 ) using a fiber - fed, bench - mounted design to maintain stability. whenever possible, the instrument uses off - the - shelf components to maintain a modest cost.   fobos supports galactic astronomy projects that require consistently well - measured ( @xmath1 km sec@xmath2 ) radial velocities for large numbers of broadly distributed and relatively bright ( @xmath3 ) stars.   the spectrograph provides wavelength coverage throughout the optical spectrum, although the instrument design was optimized for use in the range @xmath4  .   test data indicate that the instrument is stable and capable of measuring radial velocities with precision better than 3 km sec@xmath2 at a resolution of @xmath5 with minimal calibration overhead.
ferropericlase, ( mg, fe)o, is a major lower mantle mineral, and studying its properties is a fundamental step toward understanding the earth s interior. here  , we performed a first principles investigation on the properties of iron as an isolated impurity in magnesium oxide, which is the condition of ferropericlase that iron - iron interactions could be neglected.   the calculations were carried using the all - electron full - potential linearized augmented plane wave method, within the density functional theory / generalized gradient approximation plus the on - site hubbard correction.   we present the electronic and magnetic properties, electric and magnetic hyperfine splitting of this impurity in high and low spin states, for several charge states at zero pressure, which were then extended to high pressures. for the impurity in the neutral charge state  , our results indicated that there is a metastable intermediate spin state ( s=1 ), in addition to the high ( s=2 ) and low ( s=0 ) spin states.   those results were discussed in the context of an intermediate spin state, experimentally identified in ferrosilicate perovskite.
we examined the gravitational contraction of isothermal molecular cloud cores with slow rotation by means of two - dimensional numerical simulations. applying a sink - cell method  , we followed the evolution of the cloud cores up to the stages at which most of the matter accretes onto the central region ( i.e., a protostar and a rotationally - supported circumstellar disk ).   we show that both an infalling disklike envelope and a rotationally - supported disk around the central star are natural outcome of the gravitational contraction of a _ prolate _ cloud core with slow rotation.   the early evolution of the infalling envelopes resembles sheet models recently proposed by hartmann and coworkers. in the infalling disklike envelope,   the radial profiles of the density, radial velocity, and azimuthal velocity can be approximated by @xmath0, @xmath1, and @xmath2, respectively.   the fate of the infalling envelopes is also discussed.
new approach on interpretation and processing of raman spectra of complex perovskites is suggested.   raman spectra of @xmath0 and @xmath1 are successfully described on the basis of the phonon - confinement model and validity of the method is demonstrated on good agreement of experimentally obtained and computer simulated spectra of another complex perovskite, @xmath2.   the study showed that the size of nanoscale regions is a kind of an inborn characteristic of the sample and is not temperature dependent. for @xmath3,   two special temperature points, approximately 400 k and 600 k are found from the analysis of the temperature behaviour of obtained mode parameters.
in a previous paper introducing ` trans - coordinate physics ', the state of a system can not be defined along a space - like plane. a non - planar definition of state is therefore proposed that completely discards the notion of simultaneity.   the new state is illustrated in the case of a spin measurement of two spin - correlated particles, where a superluminal collapse of the state is assumed to be of the hellwig - kraus variety.   the causal loops that are commonly associated with this kind of collapse are completely avoided in this treatment.   this state definition and collapse mechanism leads to an absolute ` causal'priority among collapse events, and results in a unique minkowski architecture.   the hamiltonian of a trans - coordinate system is also proposed.   it is shown that the total square modulus of this new kind of state is conserved during an interaction.   the rules that govern the collapse of quantum mechanical wave functions are given in another previous paper.   they are at odds with the form of trans - coordinate physics, so they are restructured in the appendix.   keywords : invariance, state reduction, wave collapse.
with the advent of rxte, which is capable of broad spectral coverage and fast timing, as well as other instruments which are increasingly being used in multi - wavelength campaigns ( via both space - based and ground - based observations ), we must demand more of our theoretical models.   no current model mimics all facets of a system as complex as an x - ray binary.   however, a modern theory should qualitatively reproduce  or at the very least not fundamentally disagree with  _ all _ of cygnus x-1 s most basic average properties : energy spectrum ( viewed within a broader framework of black hole candidate spectral behavior ), power spectrum ( psd ), and time delays and coherence between variability in different energy bands.   below we discuss each of these basic properties in turn, and we assess the health of one of the currently popular theories : comptonization of photons from a cold disk.   we find that the data pose substantial challenges for this theory, as well as all other currently discussed models.
the maximum agreement forest ( maf ) problem is a well - studied problem in evolutionary biology, which asks for a largest common subforest of a given collection of phylogenetic trees with identical leaf label - set.   however, the previous work about the maf problem are mainly on two binary phylogenetic trees or two general ( i.e., binary and non - binary ) phylogenetic trees. in this paper  , we study the more general version of the problem : the maf problem on multiple general phylogenetic trees. we present a parameterized algorithm of running time @xmath0 and a @xmath1-approximation algorithm for the maf problem on multiple rooted general phylogenetic trees, and a parameterized algorithm of running time @xmath2 and a @xmath3-approximation algorithm for the maf problem on multiple unrooted general phylogenetic trees.   we also implement the parameterized algorithm and approximation algorithm for the maf problem on multiple rooted general phylogenetic trees, and test them on simulated data and biological data.    lemma corollary proposition    # 1
we reconstruct the standard model ( sm ) quark masses and the cabibbo - kobayashi - maskawa ( ckm ) matrix from a five - dimensional model, with the fifth dimension compactified on an @xmath0 orbifold.   fermions are localized only at the orbifold fixed points and the induced quark mass matrices are almost democratic.   two specific versions of our model with 15 and 24 parameters are presented, and for both versions we can reproduce the quark mass spectrum and ckm matrix correctly to the level they are observed in current experiments.   = = = = = = = = = == === = = = = = = = = = = = = = = = = ==== = = =
we established the catalog of x - ray point sources in the field of the magellanic - type spiral galaxy ngc  3109 ( ddo  236 ) from two _ rosat pspc _ observations.   of the 91 x - ray sources 26 are contained within the hi extent of ngc  3109 as derived by jobin & carignan ( 1990 ) with the vla. for 10 of these   we can determine accurate hardness ratios @xmath00.2.   we find 3 candidate agn, 2 candidate x - ray binaries and one source which may belong to either class.   we also find 2 candidate foreground stars. in a field of 8  @xmath1  8   observed with the ntt in the i - band and centered on the nucleus of ngc  3109 we determine candidates for optical counterparts in the x - ray error circle of 7 _ rosat pspc _ sources.   we apply a spectral fit to the _ rosat _ spectrum of the x - ray brightest absorbed candidate agn behind ngc  3109, rx  j1003.2 - 2607. assuming a galactic foreground hydrogen column density of @xmath2 we derive from the x - ray spectral fit, assuming reduced metallicities ( @xmath30.2 solar ), a hydrogen column density due to ngc  3109 of @xmath4.   this value is slightly larger than the hydrogen column density derived from the 21-cm observations of @xmath5.   we estimate that the molecular mass fraction of the gas is not larger than @xmath6%.
in this work, a relation is found between state dependence of bulk observables in the gauge / gravity correspondence and nonperturbative diffeomorphism invariance.   certain bulk constraints, such as the black hole information paradox, appear to obstruct the existence of a linear map from bulk operators to exact cft operators that is valid over the entire expected range of validity of the bulk effective theory. by formulating the bulk gravitational physics in the hartle - hawking framework to address these nonperturbative ir questions,   i will demonstrate, in the context of eternal ads - schwarzschild, that the problematic operators fail to satisfy the hamiltonian constraints nonperturbatively. in this way,   the map between bulk effective theory hartle - hawking wavefunctions and exact cft states can be linear on the full hilbert space.    * bulk reconstruction and the hartle - hawking wavefunction *    * daniel louis jafferis *    _ center for the fundamental laws of nature, harvard university, cambridge, ma, usa _
the paper presents a simple combinatorial method to encode 3-dimensional manifolds, basing on their heegaard diagrams.   the notion of a gauss diagram of a  3-manifold is introduced.   we check the conditions for a gauss diagram to represent a closed manifold and a manifold with boundary.
deep color magnitude diagrams extending to the main sequence provide the most direct measure of the detailed star formation history in a stellar population. with large investments of observing time, hst can obtain such data for populations out to 1 mpc, but its field of view is extremely small in comparison to the size of local group galaxies.   this limitation severely constrains our understanding of galaxy formation.   for example, the largest galaxy in the local group, andromeda, offers an ideal laboratory for studying the formation of large spiral galaxies, but the galaxy shows substructure on a variety of scales, presumably due to its violent merger history. within its remaining lifetime, hst can only sample a few sight - lines through this complex galaxy.   in contrast, a wide field imager could provide a map of andromeda s halo, outer disk, and tidal streams, revealing the spatially - dependent star formation history in each structure. the same data would enable many secondary studies, such as the age variation in andromeda s globular cluster system, gigantic samples of variable stars, and microlensing tracers of the galaxy s dark matter distribution.
we present an holographical soft wall model which is able to reproduce regge spectra for hadrons with an arbitrary number of constituents.   the model includes the anomalous dimension of operators that create hadrons, together with a dilaton, whose form is suggested by einstein s equations and the ads metric.   address = departamento de fsica y centro de estudios subatmicos, + universidad tcnica federico santa mara, + casilla 110-v, valparaso, chile
this paper is devoted to the study of transformations on metric spaces. it is done in an effort to produce qualitative version of quasi - isometries which takes into account the asymptotic behavior of the gromov product in hyperbolic spaces.   we characterize a quotient semigroup of such transformations on teichmller space by use of simplicial automorphisms of the complex of curves, and we will see that such transformation is recognized as a  coarsification " of isometries on teichmller space which is rigid at infinity.   we also show a hyperbolic characteristic that any finite dimensional teichmller space does not admit ( quasi)-invertible rough - homothety.
noticeable deviations from the prediction of the fiducial lcdm cosmology are found in the angular power spectrum of the cmb. besides large - angle anomalies, the wmap @xmath0 year data revealed a dip in the power spectrum at @xmath1, which seemed to disappear in the @xmath2 year and subsequent angular power spectra. using the wmap single @xmath0, @xmath2, and @xmath3 year data as well as the total @xmath4 year coadded data, we study the intensity and spatial distribution of this feature in order to unveil its origin and its implications for the cosmological parameters.   we show that in all wmap data releases there is a substantial suppression of the first doppler peak in a region near the north ecliptic pole.
@xmath0, @xmath1, and @xmath2 band data from the two micron all - sky survey ( 2mass ) are used to study the effects of differential reddening across the three massive galactic globular clusters @xmath3 centauri, ngc 6388, and ngc 6441.   evidence is found that variable extinction may produce false detections of tidal tails around @xmath3 centauri.   we also investigate what appears to be relatively strong differential reddening towards ngc 6388 and ngc 6441, and find that differential extinction may be exaggerating the need for a metallicity spread to explain the width of the red giant branches for these two clusters.   finally, we consider the implications of these results for the connection between unusual, multipopulation globular clusters and the cores of dwarf spheroidal galaxies ( dsph ).
we investigate a possibility of estimating mass of an isolated rapidly rotating neutron star ( ns ) from a continuous gravitational wave ( gw ) signal emitted by the ns.   when the gw passes through the gravitational potential of the ns, the gw takes a slightly longer time to travel to an observer than it does in the absence of the ns.   such a time dilation effect holds also for photons and is often referred to as the gravitational time delay ( or the shapiro time delay ). correspondingly, the phase of the gw from the ns shifts due to the coulomb type gravitational potential of the ns, and the resulting logarithmic phase shift depends on the mass, the spin frequency of the ns, and the distance to the ns.   we show that the ns mass can, in principle, be obtained by making use of the phase shift difference between two modes of the continuous gw such as once and twice spin frequency modes induced by a freely precessing ns or a ns containing a pinned superfluid core.   we estimate the measurement accuracy of the ns mass using monte carlo simulations and find that the mass of the ns with its ellipticity @xmath0 at 1 kpc is typically measurable with an accuracy @xmath1 using einstein telescope.
recent results are reviewed on galaxy dynamics, bar evolution, destruction and re - formation, cold gas accretion, gas radial flows and agn fueling, minor mergers. some problems of galaxy evolution are discussed in particular, exchange of angular momentum, radial migration through resonant scattering, and consequences on abundance gradients, the frequency of bulgeless galaxies, and the relative role of secular evolution and hierarchical formation.
in a recent paper, liddle and urena - lopez suggested that to have a unified model of inflation and dark matter is imperative to have a proper reheating process where part of the inflaton field remains. in this paper   i propose a model where this is possible.   i found that, incorporating the effect of plasma masses generated by the inflaton products, enable us to stop the process.   a numerical estimated model is presented.
new extra series of conserved densities for the polytropic gas model and nonlinear elasticity equation are obtained without any references to the recursion operator or to the lax operator formalism.   our method based on the utilization of the symmetry operators and allows us to obtain the densities of arbitrary homogeneity dimensions.   the non polynomial densities with logarithmic behavior are presented as an example.   the special attention is paid for the singular case @xmath0 for which we found new non homogeneous solutions expressed in terms of the elementary functions.
the distribution of the stellar and gaseous components in low surface brightness galaxies has been determined directly from optical and hi imaging.   the distribution of what might be the dominant mass component, the dark matter, which is inferred from rotation curves, is far harder to determine.   although the rotation curves themselves can be determined fairly accurately from hi synthesis observations, and in particular from h@xmath0 spectroscopy, the uncertainty in the mass modeling leaves room for a wide range of possible dark matter distributions, ranging from maximum stellar disks with shallow dark halos to cuspy dark halos with little mass in stars.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
this paper describes the first optical spectroscopic survey of class i sources ( also known as embedded sources and protostars ) in the taurus - auriga dark cloud.   we detect 10 of the 24 known class i sources in the cloud at 55009000 . all detected class   i sources have strong h@xmath0 emission ; most also have strong  and  emission.   these data  together with high quality optical spectra of t tauri stars in the taurus - auriga cloud  demonstrate that forbidden emission lines are stronger and more common in class i sources than in t tauri stars.   our results also provide a clear discriminant in the frequency of forbidden line emission between weak - emission and classical t tauri stars.   in addition to strong emission lines, three class i sources have prominent tio absorption bands.   the m - type central stars of these sources mingle with optically visible t tauri stars in the hr diagram and lie somewhat below both the birthline for spherical accretion and the deuterium burning sequence for disc accretion.   4ex    to appear in    _ the astronomical journal _   june 1998    4ex
we present a study of 9 galaxy groups with evidence for non - gaussianity in their velocity distributions out to 4@xmath0.   this sample is taken from 57 groups selected from the 2pigg catalog of galaxy groups.   statistical analysis indicates that non - gaussian groups have masses significantly higher than gaussian groups.   we also have found that all non - gaussian systems seem to be composed of multiple velocity modes. besides  , our results indicate that multimodal groups should be considered as a set of individual units with their own properties.   in particular, we have found that the mass distribution of such units are similar to that of gaussian groups.   our results reinforce the idea of non - gaussian systems as complex structures in the phase space, likely corresponding to secondary infall aggregations at a stage before virialization.   the understanding of these objects is relevant for cosmological studies using groups and clusters through the mass function evolution.       galaxies  groups.
we report on stellar mgi  emission at 12  from @xmath0 cmi ( procyon ), a star slightly hotter than the sun.   solar mgi  emission is well - known and its formation was successfully explained in detail by @xcite. here, for the first time, we compare synthetic spectra of the emission lines at @xmath1 with observations of a star other than the sun.   the use of these lines as stellar diagnostics has been anticipated for 10 years or more ( see, e.g., *???   * ).   we find that the model reproduces the observed emission in procyon quite well.   we expect that high - resolution spectrographs on @xmath2 m telescopes will finally be able to exploit these new diagnostics.
powered by a supermassive black hole with an accretion disk, the spectra of active galactic nuclei ( agns ) are characterized by prominent emission lines including balmer lines.   the unification schemes of agns require the existence of a thick molecular torus that may hide the broad emission line region from the view of observers near the equatorial direction. in this configuration  , one may expect that the far uv radiation from the central engine can be raman scattered by neutral hydrogen to reappear around balmer and paschen emission lines which can be identified with broad wings.   we produce h@xmath0, h@xmath1 and pa@xmath0 wings using a monte carlo technique to investigate their properties.   the neutral scattering region is assumed to be a cylindrical torus specified by the inner and outer radii and the height. while the covering factor of the scattering region affects the overall strengths of the wings, the wing widths are primarily dependent on the neutral hydrogen column density @xmath2 being roughly proportional to @xmath3. in particular, with @xmath4   the h@xmath0 wings typically show a width @xmath5.   we also find that h@xmath0 and pa@xmath0 wing profiles are asymmetric with the red part stronger than the blue part and an opposite behavior is seen for h@xmath1 wings.
we continue our programme of extended single - site observations of pulsting subdwarf b ( sdb ) stars and present the results of extensive time series photometry to resolve the pulsation spectra for use in asteroseismological analyses.   pg  0154 + 182, hs  1824 + 5745, and hs2151 + 0857 were observed at the mdm observatory during 2004 and 2005.   our observations are sufficient to resolve the pulsations of all three target stars.   we extend the number of known frequencies for pg  0154 + 182 from one to six, confirm that hs  1824 + 5745 is a mono - periodic pulsator, and extend the number of known frequencies to five for hs  2151 + 0857.   we perform standard tests to search for multiplet structure, measure amplitude variations as pertains to stochastic excitation, and examine the mode density to constrain the mode degree @xmath0.   stars : oscillations  stars : variables  stars : individual ( pg  0154 + 182, hs  1824 + 5745, hs  2151 + 0857 )  stars : subdwarfs
the perspectives of two new nonstandard methods of transversal quark polarization measurement are considered : the jet handedness and the so - called `` collins effect '' due to spin dependent t - odd fragmentation function responsible for the left - right asymmetry in fragmenting of transversally polarized quarks.   recent experimental indications in favor of these effects are observed :    1.the correlation of the t - odd one - particle fragmentation functions found by delphi in @xmath0-jet decay.   integrated over the fraction of longitudinal and transversal momenta, this correlation is of 1.6% order, which means order of 13% for the analyzing power.   2.a rather large ( @xmath1 ) handedness transversal to the production plane observed in the diffractive production of ( @xmath2 ) triples from nuclei by the @xmath3 @xmath4beam.   it shows a clear dynamic origin and resembles the single spin asymmetry behavior.   all this makes us hope to use these effects in polarized dis experiments for transversity measurement.   the first estimation of transversity was done by using the azimuthal asymmetry in semi - inclusive dis recently measured by hermes and smc.
the quantum theory of polarized light allows to model scattering in the solar atmosphere for inferring its properties.   this powerful approach has revealed two key long - standing problems in solar physics : the puzzling dilemmas between theory and observations in several anomalously polarized spectral lines ; and the need of inferring the ubiquitous weak chromospheric magnetic fields, which requires discriminating the hanle effect in dynamic optically thick plasmas.   however, the ever - present dynamics, i.e. the temporal evolution of heatings and macroscopic motions, has been widely disregarded when modeling and interpreting the scattering polarization.   this has hindered a consistent theoretical solution to the puzzle while falsifying the hanle diagnosis. here  , we show that the dynamical evolution is a keystone for solving both problems because its systematic impact allows to explain the observations from `` anomalous '' instantaneous polarization signals.   evolution accounted for, we reproduce amplitudes and ( spectral and spatial ) shapes of the ca i 4227  polarization at solar disk center, identifying a restrictive arrangement of magnetic fields, kinematics, heatings, and spatio - temporal resolution.   we find that the joint action of dynamics, hanle effect, and low temporal resolutions mimics zeeman linear polarization profiles, the true weak - field zeeman signals being negligible.   our results allow to reinterpret many polarization signals of the solar spectra and support time - dependent scattering polarization as a powerful tool for deciphering the spatio - temporal distribution of chromospheric heatings and fields.   this approach may be a key aid in developing hanle diagnosis for the solar atmosphere.
this is the first paper about the fragmentation and mass outflow in the molecular cloud by using three - dimensional mhd nested - grid simulations.   the binary star formation process is studied paying particular attention to the fragmentation of a rotating magnetized molecular cloud.   we assume an isothermal rotating and magnetized cylindrical cloud in hydrostatic balance.   non - axisymmetric as well as axisymmetric perturbations are added to the initial state and the subsequent evolutions are studied.   the evolution is characterized by three parameters : the amplitude of the non - axisymmetric perturbations, the rotation speed, and the magnetic field strength. as a result  , it is found that non - axisymmetry hardly evolves in the early phase, but begins to grow after the gas contracts and forms a thin disk.   disk formation is strongly promoted by the rotation speed and the magnetic field strength.   there are two types of fragmentation : fragmentation from a ring and that from a bar.   thin adiabatic cores fragment if a thickness is smaller than 1/4 of the radius. for the fragments to survive  , they should be formed in a heavily elongated barred core or a flat round disk. in the models showing fragmentation,   outflows from respective fragments are found as well as those driven by the rotating bar or the disk.   binaries : general  ism : jets and outflows  ism : magnetic fields mhd stars : formation.
we apply the holographic principle to a flat dark energy dominated friedmann - robertson - walker spacetime filled with a tachyon scalar field with constant equation of state @xmath0, both for @xmath1 and @xmath2. by using a geometrical covariant procedure, which allows the construction of holographic hypersurfaces, we have obtained for each case the position of the preferred screen and   have then compared these with those obtained by using the holographic dark energy model with the future event horizon as the infrared cutoff. in the phantom scenario,   one of the two obtained holographic screens is placed on the big rip hypersurface, both for the covariant holographic formalism and the holographic phantom model.   it is also analyzed whether the existence of these preferred screens allows a mathematically consistent formulation of fundamental theories based on the existence of a s matrix at infinite distances.
an analytic solution of the hartree - fock problem for a 2deg at filling 1/3 and half an electron per unit cell is presented.   the coulomb interaction dynamically breaks the first landau level in three narrow sub - bands, one of which is fully occupied and the other empty, as in the composite fermion model.   the localized orbitals associated to the bloch like single electron wavefunctions are nearly static, resembling the angular momentum eigenstates within a landau level for non - interacting fermions.   strong correlations are expected owing to the large charge density overlap between neighboring plaquettes.   a numerical evaluation brings the cohesive energy close to that of the best present day models.   it is also found that correlations are long range, requiring over 50 particles spread over a finite sample to approach convergence.   since presently allowed exact calculations are far from this number, the question of how relevant the considered wave - function is for the description of the ground state of the 2deg system remains open.   pacs numbers : 73.43.cd, 73.43.-f       * on leave of absence from _ theoretical physics group, instituto de ciberntica, matematica y fsica, calle e, no.   309, vedado, la habana, cuba.   _     preprint ictp, ic/2003/60(2003 )
the ultraviolet coronagraph spectrometer ( uvcs ) aboard the _ soho _ satellite has observed very fast coronal mass ejections ( cmes ) associated with x - class flares.   these events show spectral signatures different than those seen in most other cmes in terms of very rapid disruption of the pre - cme streamer, very high doppler shifts and high temperature plasma visible in the  emission line.   this paper describes three very similar events on 21 april, 23 july and 24 august 2002 associated with x - class flares.   we determine the physical parameters of the pre - cme streamers and discuss the geometrical and physical nature of the streamer blowouts. in the 21 april event, the hot plasma seen as  is not related to the structure seen in  by sumer at lower heights.   it has the form of a rapidly expanding fan, quite likely a current sheet. in the august event,   on the other hand, the  is probably a bubble of hot plasma formed by reconnection in the wake of the cme.   c iii emission from the july 23 flare is detected as stray light in the uvcs aperture.   it precedes the hard x - ray brightening by about 2 minutes.
heterodyne, eight - port homodyne and six - port homodyne detectors belong to the class of two - photocurrent devices.   their full equivalence in probing radiation field has been proved both for ideal and not fully efficient photodetectors.   the output probability distribution has been also evaluated for a generic probe mode.
high - order harmonic generation ( hhg ) by hydrogenlike atoms / ions in the uniform periodic electric field, formed by the two linearly polarized counterpropagating laser beams of relativistic intensities, is studied.   the relativistic quantum theory of hhg in such fields, at which the impeding factor of relativistic magnetic drift of a strong wave can be eliminated, is presented arising from the dirac equation.   specifically, a scheme of hhg in underdense plasma with the copropagating ultraintense laser and fast ion beams is proposed.
measuring, characterizing and modelling the slow dynamics of glassy soft matter is a great challenge, with an impact that ranges from industrial applications to fundamental issues in modern statistical physics, such as the glass transition and the description of out - of - equilibrium systems.   although our understanding of these phenomena is still far from complete, recent simulations and novel theoretical approaches and experimental methods have shed new light on the dynamics of soft glassy materials. in this paper, we review the work of the last few years, with an emphasis on experiments in four distinct and yet related areas : the existence of two different glass states ( attractive and repulsive ), the dynamics of systems very far from equilibrium, the effect of an external perturbation on glassy materials, and dynamical heterogeneity.
a non - markovian stochastic predator - prey model is introduced in which the prey are immobile plants and predators are diffusing herbivors.   the model is studied by both mean - field approximation ( mfa)and computer simulations.   the mfa results a series of bifurcations in the phase space of mean predator and prey densities, leading to a chaotic phase. because of emerging correlations between the two species distributions, the interaction rate alters and if it is set the value which is obtained from the simulation, then the chaotic phase disappears.    _   @xmath0 institute for studies in theoretical physics and mathematics, p.o.box 19395 - 5531, tehran, iran _    _ @xmath1 department of physics, sharif university of technology, p.o.box 11365 - 9161, tehran, iran _   pacs :
i analyze several catalogs of known visual and spectroscopic binaries and conclude that a large number of binaries is missing in current catalogs.   samples of the best studied ( nearby and bright ) stars indicate that the true binary fraction may be as high as 95%.   a preliminary analysis indicates that these binaries can affect the astrometry significantly.
we report on a search for hidden photon cold dark matter ( hp cdm ) using a novel technique with a dish antenna.   we constructed two independent apparatus : one is aiming at the detection of the hp with a mass of @xmath0 which employs optical instruments, and the other is for a mass of @xmath1 utilizing a commercially available parabolic antenna facing on a plane reflector. from the result of the measurements, we found no evidence for the existence of hp cdm and set upper limits on the photon - hp mixing parameter @xmath2.
nuclear partition functions were calculated for a grid of temperatures from @xmath0 k to @xmath1 k ( @xmath2 mev ) within a fermi - gas approach, including all nuclides from the proton - dripline to the neutron - dripline with proton number @xmath3.   the calculation is based on a nuclear level density description published elsewhere, thus extending the previous tables of partition functions beyond @xmath4 k. additional high temperature corrections had to be applied.
if dark matter has a non - zero self - interaction cross - section, then dark matter halos of individual galaxies in cluster cores should experience a drag force from the ambient dark matter of the cluster, which will not affect the stellar components of galaxies, and thus will lead to a separation between the stellar and dark matter.   if the cross - section is only a few decades below its current astrophysically determined upper limit, then kpc - scale separations should result.   however, such separations will be observable only under very favorable conditions.   abell 3827 is a nearby late stage cluster merger with four massive central ellipticals within @xmath0  kpc of each other.   the ten strong lensing images tightly surrounding the ellipticals provide an excellent set of constraints for a free - form lens reconstruction.   our free - form mass maps show a massive dark extended clump, about @xmath1  kpc from one of the ellipticals.   the robustness of this result has been tested with many reconstructions, and confirmed with experiments using synthetic lens mass distributions.   interpreted in terms of dark matter collisionality, our result yields @xmath2  @xmath3  g@xmath4, where @xmath5 is the merger s age.
a new model is formulated of the sociological effect of the spiral of silence, introduced by elisabeth noelle - neumann in 1974.   the probability that a new opinion is openly expressed decreases with the difference between this new opinion and the perceived opinion of the majority.   we also assume that the system is open, i.e. some people enter and some leave during the process of the opinion formation.   an influence of a leader is simulated by a comparison of two runs of the simulation, where the leader has different opinion in each run.   the difference of the mean expressed opinions in these two runs persists long after the leader s leave.
we show that the keplerian thin disk in quiescent soft x - ray transients can not extend down to the last stable orbit around the central black hole.   we analyse the properties of the narayan, mcclintock & yi ( 1996 ) model of quiescent soft x - ray transients in which the cold keplerian disk has its inner edge at a large transition radius and transforms to a hot, advection - dominated flow on the inside.   we show that outbursts of transient sources could be triggered in this model either by a pure thermal accretion disk instability or by a disk instability generated by an enhanced mass transfer from the stellar companion.   both mechanisms operate in the outer thin disk and could be at work, either in different systems or in the same system at different epochs, depending on the mass transfer rate and the value of the viscosity parameter @xmath0 of the thin disk.   we show that the recurrence time between outbursts in sxts can be explained with values of @xmath0 similar to these required by the dwarf nova disk instability model instead of the unreasonably low values needed in the model in which the thin disks extends down to the last stable orbit.   we extend the narayan, mcclintock & yi ( 1996 ) model to the case when the outer disk is non - stationary.   we show that such disk is too cold to account for the observed uv flux.   this difficulty is common to all models in which the outer disk is assumed to be optically thick.   a&a = = = 1=1=0pt = 2=2=0pt
we present the discovery of three late type ( @xmath0t4.5 ) brown dwarfs, including a probable y dwarf, in the wfc3 infrared spectroscopic parallels ( wisp ) survey.   we use the g141 grism spectra to determine the spectral types of the dwarfs and derive distance estimates based on a comparison with nearby t dwarfs with known parallaxes.   these are the most distant spectroscopically confirmed t / y dwarfs, with the farthest at an estimated distance of @xmath1400 pc.   we compare the number of cold dwarfs found in the wisp survey with simulations of the brown dwarf mass function.   the number found is generally consistent with an initial stellar mass function @xmath2 with @xmath3 = 0.00.5, although the identification of a y dwarf is somewhat surprising and may be indicative of either a flatter absolute magnitude / spectral type relation than previously reported or an upturn in the number of very late type brown dwarfs in the observed volume.
we investigate the spin behavior of close - in rocky planets and the implications for their orbital evolution. considering that the planet rotation evolves under simultaneous actions of the torque due to the equatorial deformation and the tidal torque,   both raised by the central star, we analyze the possibility of temporary captures in spin - orbit resonances.    the results of the numerical simulations of the exact equations of motions indicate that, whenever the planet rotation is trapped in a resonant motion, the orbital decay and the eccentricity damping are faster than the ones in which the rotation follows the so - called pseudo - synchronization.   analytical results obtained through the averaged equations of the spin - orbit problem show a good agreement with the numerical simulations.   we apply the analysis to the cases of the recently discovered hot super - earths kepler-10**b * *, gj 3634**b * * and 55 cnc**e**. the simulated dynamical history of these systems indicates the possibility of capture in several spin - orbit resonances ; particularly, gj 3634**b * * and 55 cnc**e * * can currently evolve under a non - synchronous resonant motion for suitable values of the parameters.   moreover, 55 cnc**e * * may avoid a chaotic rotation behavior by evolving towards synchronization through successive temporary resonant trappings.   celestial mechanics  planets and satellites : general.
there are a number of theoretical predictions for astrophysical and cosmological objects, which emit high frequency ( @xmath0  hz ) gravitation waves ( gw ) or contribute somehow to the stochastic high frequency gw background. here   we propose a new sensitive detector in this frequency band, which is based on existing cryogenic ultra - high quality factor quartz bulk acoustic wave cavity technology, coupled to near - quantum - limited squid amplifiers at @xmath1  mk.   we show that spectral strain sensitivities reaching @xmath2 per @xmath3 per mode is possible, which in principle can cover the frequency range with multiple ( @xmath4 ) modes with quality factors varying between @xmath5 allowing wide bandwidth detection. due to its compactness and well established manufacturing process,   the system is easily scalable into arrays and distributed networks that can also impact the overall sensitivity and introduce coincidence analysis to ensure no false detections.
new radio observations of the counterpart of the ultraluminous x - ray source in ngc 5408 show for the first time that the radio emission is resolved with an angular size of @xmath0 to @xmath1.   this corresponds to a physical size of 3546  pc, and rules out interpretation of the radio emission as beamed emission from a relativistic jet.   in addition, the radio spectral index of the counterpart is well determined from three frequencies and found to be @xmath2=@xmath30.8 @xmath40.2.   the radio emission is likely to be optically - thin synchrotron emission from a nebula surrounding the x - ray source.   the radio luminosity of the counterpart is @xmath5 and the minimum energy required to power the nebula is @xmath6.   these values are two orders of magnitude larger than in any galactic nebula powered by an accreting compact object.
after isaac newton was knighted by queen anne in 1705 he adopted an unusual coat of arms : a pair of human tibi  crossed on a black background, like a pirate flag without the skull.   after some general reflections on newton s monumental scientific achievements and on his enigmatic life, we investigate the story of his coat of arms.   we also discuss how its simple design illustrates the concept of chirality, which would later play an important role in the philosophical arguments about newton s conception of space, as well as in the development of modern chemistry and particle physics.   + _ keywords : _ isaac newton, chirality, heraldry + _ pacs : _ 01.65.+g, 11.30.rd    = 1.74 cm the hearts of old gave hands, + but our new heraldry is hands, not hearts.   + `  _ othello _, act 3, scene 4
in this article we show the modification of the number of neutrino events ( @xmath0 ) caused by lorentz invariant violation ( liv ), @xmath1 and @xmath2, in neutrino oscillations for a neutrino factory at a distance of 7500 km.   the momentum of the muons can vary from 10 - 50  gev and we consider @xmath3 decays per year.   the modifications in the number of events caused by this @xmath4 liv parameter could be a strong signal of new physics in a future neutrino factory.
we study the production and decay of the neutral top - pion @xmath0 predicted by topcolor - assisted technicolor(tc2 ) theory.   our results show that, except the dominant decay modes @xmath1, @xmath2 and @xmath3, the @xmath0 can also decay into @xmath4 and @xmath5 modes  . it can be significantly produced at high energy @xmath6 collider(lc ) experiments via the processes @xmath7 and @xmath8.   we further calculate the production cross sections of the processes @xmath9 and @xmath10.   we find that the signatures of the neutral top - pion @xmath0 can be detected via these processes.    *   pacs number(s ) * : 12.60nz, 14.80.mz
the lambda - phi4 kink is linearly and topologically stable. we study how extra energy perturbations are dissipated beyond the linear regime.   we found that depending on the width, amplitude and energy of a gaussian perturbation different scenarios are possible : radiation, oscillons creation, kink anti - kink pairs production and shock waves.   * keywords : * applications of nonlinear sciences, nonlinear dynamics, kink, stability, lambda phi 4  . +
using monte carlo simulations within the empirical potential approach, we examine the effect produced by the surface environment on the atomic level stresses in tetrahedral amorphous carbon.   both the distribution of stresses and the distributions of sp@xmath0 and sp@xmath1 atoms as a function of depth from the surface are highly inhomogeneous.   they show the same close relationship between local stress and bonding hybridization found previously in the bulk of the material.   compressive local stress favors the formation of sp@xmath1 sites, while tensile stress favors the formation of sp@xmath0 sites.
given their proximity and age differences, nearby groups of young stars are valuable laboratories for investigations of disk evolution and diversity. the estimated 10-myr age of groups like the tw hydrae association provides a strong constraint on disk evolution timescales and fills a significant gap in the age sequence between 1-myr - old t tauri stars in molecular clouds and 50-myr - old nearby open clusters.   i review the results of recent and on - going studies of dusty disks in three nearby groups tw hya, @xmath0 cha and mbm 12 that suggest rapid evolution of inner disks.   however, it is unlikely that there is a universal evolutionary timescale for protoplanetary disks, especially when the influence of companion stars is taken into account.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present the uv, optical, x - ray, and radio properties of the type iib sn  2008ax discovered in ngc  4490.   the observations in the uv are one of the earliest of a type iib supernova ( sn ). on approximately day four after the explosion, a dramatic upturn in the @xmath0 and @xmath1 ( @xmath2 ) light curves occurred after an intitial rapid decline which is attributed to adiabatic cooling after the initial shock breakout.   this rapid decline and upturn is reminiscent of the type iib sn  1993j on day six after the explosion.   optical / near - ir spectra taken around the peak reveal prominent @xmath3, hei, and caii absorption lines.   a fading x - ray source is also located at the position of sn  2008ax, implying an interaction of the sn shock with the surrounding circumstellar material and a mass - loss rate of the progenitor of @xmath4. the unusual time evolution ( @xmath5 ) of the @xmath6   peak radio luminosity provides further evidence that the mass - loss rate is low. combining the uv, optical, x - ray, and radio data with models of helium exploding stars implies the progenitor of sn  2008ax was an unmixed star in an interacting - binary.   modeling of the sn light curve suggests a kinetic energy ( @xmath7 ) of @xmath8, an ejecta mass ( @xmath9 ) of @xmath10, and a nickel mass ( @xmath11 ) of @xmath12.
this paper presents results of comparison between observations of coronal holes in the uv ( soho eit ) and microwave emission ( 17, 5.7 ghz, 327 and 150.9 mhz, norh, ssrt and nancy radioheliographs ), and solar wind parameters, according to the ace spacecraft data over the period 12  march31  may  2007.   increase in the solar wind velocity up to @xmath0600 @xmath1 was found to correlate with decrease in the uv flux in the central parts of the solar disk.   the connection between parameters of the microwave emission at three different solar atmosphere levels and the solar wind velocity near the earth s orbit was determined.   this connection suggests existence of common mechanisms of solar wind acceleration from chromospheric altitudes to the upper corona.   we also suppose existence of two different mechanisms of the solar wind acceleration at altitudes of less and more than one solar radius.
in the hydrodynamic approximation we obtain analytic solutions to the gross - pitaevskii equation with positive scattering length which describe expansions of the bose - einstein condensates in quasi - one and quasi - two dimensional geometries.   the expansion laws are expressed in terms of the initial sizes of the condensate and the trap frequencies before release, that is in terms of experimentally measurable parameters only.   three - dimensional effects are estimated with the use of variational approach.   the analytical formulae show good agreement with available experimental data.
we consider the photodissociation of ground - state bosonic molecules trapped in an optical lattice potential into a two - component gas of fermionic atoms. the system is assumed to be described by a single - band resonantly - coupled bose - fermi hubbard model.   we show that in the strong fermion - fermion interaction limit the dissociation dynamics is governed by a spin - boson lattice hamiltonian. in the framework of a mean - field analysis based on a generalized gutzwiller ansatz  , we then examine the crossover of the dissociation from a regime of independent single - site dynamics to a regime of cooperative dynamics as the molecular tunneling increases.   we also show that in the limits of weak and strong intersite tunneling the mean - field solutions agree well with the results from the quantum optical jaynes - cummings and tavis - cummings models, respectively. finally, we identify two types of self - trapping transitions, a _ coherent _ and an _ incoherent _ one, depending on the ratio of the repulsive molecule - molecule interaction strength to molecular tunneling.
a quantum mechanical picture is presented to describe the behavior of confined spinons in a variety of @xmath0 chains.   the confinement is due to dimerization and frustration and it manifests itself as a nonlinear potential @xmath1, centered at chain ends ( @xmath2 ) or produced by modulation kinks ( @xmath3 ).   the calculation extends to weak or zero frustration some previous ideas valid for spinons in strongly frustrated spin chains.   the local magnetization patterns of the confined spinons are calculated.   a ( minimum ) enhancement of the local moments of about 11/3 over a single @xmath0 is found.   estimates for excitation energies and binding lengths are obtained.
drift ordered fluid models are widely applied in studies of low - frequency turbulence in the edge and scrape - off layer regions of magnetically confined plasmas. here,   we show how collisional transport across the magnetic field is self - consistently incorporated into drift - fluid models without altering the drift - fluid energy integral.   we demonstrate that the inclusion of collisional transport in drift - fluid models gives rise to diffusion of particle density, momentum and pressures in drift - fluid turbulence models and thereby obviate the customary use of artificial diffusion in turbulence simulations.   we further derive a computationally efficient, two - dimensional model which can be time integrated for several turbulence de - correlation times using only limited computational resources.   the model describes interchange turbulence in a two - dimensional plane perpendicular to the magnetic field located at the outboard midplane of a tokamak.   the model domain has two regions modeling open and closed field lines.   the model employs a computational expedient model for collisional transport.   numerical simulations show good agreement between the full and the simplified model for collisional transport.
multiplicative white - noise stochastic processes continuously attract the attention of a wide area of scientific research. the variety of prescriptions available to define it difficults the development of general tools for its characterization. in this work,   we study equilibrium properties of markovian multiplicative white - noise processes. for this  , we define the time reversal transformation for this kind of processes, taking into account that the asymptotic stationary probability distribution depends on the prescription. representing the stochastic process in a functional grassman formalism  , we avoid the necessity of fixing a particular prescription. in this framework  , we analyze equilibrium properties and study hidden symmetries of the process.   we show that, using a careful definition of equilibrium distribution and taken into account the appropriate time reversal transformation, usual equilibrium properties are satisfied for any prescription.   finally, we present a detailed deduction of a covariant supersymmetric formulation of a multiplicative markovian white - noise process and study some of the constraints it imposes on correlation functions using ward - takahashi identities.
in this study, we obtain the approximate analytical solutions of the radial schrdinger equation for the deng - fan diatomic molecular potential by using exact quantization rule approach.   the wave functions have been expressed by hypergeometric functions via the functional analysis approach.   an extension to rotational - vibrational energy eigenvalues of some diatomic molecules are also presented.   it is shown that the calculated energy levels are in good agreement with the ones obtained previously @xmath0 ( shifted deng - fan ).   * keywords * : schrdinger equation ; exact quantization rule ; functional analysis ; deng - fan potential.
studies of galaxy clusters have proved crucial in helping to establish the standard model of cosmology, with a universe dominated by dark matter and dark energy. a theoretical basis that describes clusters as massive  , multi - component, quasi - equilibrium systems is growing in its capability to interpret multi - wavelength observations of expanding scope and sensitivity.   we review current cosmological results, including contributions to fundamental physics, obtained from observations of galaxy clusters.   these results are consistent with and complementary to those from other methods.   we highlight several areas of opportunity for the next few years, and emphasize the need for accurate modeling of survey selection and sources of systematic error.   capitalizing on these opportunities will require a multi - wavelength approach and the application of rigorous statistical frameworks, utilizing the combined strengths of observers, simulators and theorists.   keywords : cosmology, dark energy, dark matter, galaxy clusters, intracluster medium, large scale structure
we compare the highly clustered populations of very high redshift galaxies with proto - clusters identified numerically in a standard @xmath0cdm universe ( @xmath1 ) simulation.   we evolve @xmath2 dark matter particles in a comoving box of side @xmath3. by the present day   there are 63 cluster sized objects of mass in excess of @xmath4 in this box.   we trace these clusters back to higher redshift finding that their progenitors at @xmath5@xmath6 are extended regions of typically 2040 mpc ( comoving ) in size, with dark halos of mass in excess of @xmath7 and are overdense by typically 1.313 times the cosmological mean density.   comparison with the observation of ly@xmath8 emitting ( laes ) galaxies at @xmath9 and at @xmath10 indicates that the observed excess clustering is consistent with that expected for a proto - cluster region if laes typically correspond to massive dark halos of more than @xmath7.   we give a brief discussion on the relation between high redshift concentration of massive dark halos and present day rich clusters of galaxies.
the energy density of a scalar field @xmath0 with potential @xmath1, @xmath2, behaves like a time - variable cosmological constant that could contribute significantly to the present energy density.   predictions of this spatially - flat model are compared to recent type ia supernovae apparent magnitude versus redshift data.   a large region of model parameter space is consistent with current observations.   ( these constraints are based on the exact scalar field model equations of motion, not on the widely used time - independent equation of state fluid approximation equations of motion. )   we examine the consequences of also incorporating constraints from recent measurements of the hubble parameter and the age of the universe in the constant and time - variable cosmological constant models.   we also study the effect of using a non - informative prior for the density parameter.
here we show that variations of temperature, even of a few degrees in amplitude, induce the ageing of a granular pile. in particular, we report measurements of physical properties of a granular heap submitted to thermal cycles.   namely, we focus on the evolution of the thermal linear - expansion coefficient and of the thermal conductivity of the pile with the number of cycles.   the present contribution nicely supplements a recent article we published elsewhere [ phys.   rev.   lett.   * 101 *, 148303 ( 2008 ) ] and introduces a different and promising method to impose temperature cycles to a granular pile.   address = universit de lyon, laboratoire de physique, ecole normale suprieure de lyon, cnrs, 46 alle ditalie, 69364 lyon cedex 07, france
when planning new facilities, one is interested to know whether and by how much the new technique is superior to already existing ones.   we describe a general approach permitting to evaluate the relative merits of various techniques used in astrophysical observations, following the theory of model parameter estimation.   it is applied to compare two - aperture optical long baseline interferometry to classical spectroscopy, both used to define the model parameters of the p  cyg wind.   the wind modeling was done using an efficient approximation for computation of the line source function ; it allowed to analyse about @xmath0 points in the parametric space of p  cyg envelope models.   it is shown that interferometry offers no real advantage if the object can be described by stationary spherically symmetric models with a priori fixed thermal structure. however,   if the object must be described by a model with a large number of free parameters, e.g. when the thermal structure of the envelope is not fixed a priori, then the interferometric measurements can reduce the error in model parameters determination by an order of magnitude. in the case of p   cyg, the reduction of errors provided by interferometry is highest for the baseline lengths in the range 4590 m. this illustrates the capacity of the proposed method to be used for optimization of interferometric configurations.   the simplifications adopted for this first trial application are critically analyzed, and future improvements are indicated.
the cross section for the removal of high - momentum protons from @xmath0 is calculated for high missing energies.   the admixture of high - momentum nucleons in the @xmath0 ground state is obtained by calculating the single - hole spectral function directly in the finite nucleus with the inclusion of short - range and tensor correlations induced by a realistic meson - exchange interaction.   the presence of high - momentum nucleons in the transition to final states in @xmath1 at 60 - 100 mev missing energy is converted to the coincidence cross section for the @xmath2 reaction by including the coupling to the electromagnetic probe and the final state interactions of the outgoing proton in the same way as in the standard analysis of the experimental data.   detectable cross sections for the removal of a single proton at these high missing energies are obtained which are considerably larger at higher missing momentum than the corresponding cross sections for the @xmath3-wave quasihole transitions.   cross sections for these quasihole transitions are compared with the most recent experimental data available.
we discuss the problem of full counting statistics for periodic pumping.   the probability generating function is usually defined on a circle of the `` physical '' values of the counting parameter, with its periodicity corresponding to charge quantization.   the extensive part of the generating function can either be an analytic function on this circle or have singularities.   these two cases may be interpreted as different thermodynamic phases in time domain.   we discuss several examples of phase transitions between these phases for classical and quantum systems.   finally, we prove a criterion for the `` analytic '' phase in the problem of a quantum pump for noninteracting fermions.
several experimental measurements are expressed in the form of one - dimensio - nal profiles, for which there is a scarcity of methodologies able to classify the pertinence of a given result to a specific group.   the polarization curves that evaluate the corrosion kinetics of electrodes in corrosive media are an application where the behavior is chiefly analyzed from profiles.   polarization curves are indeed a classic method to determine the global kinetics of metallic electrodes, but the strong nonlinearity from different metals and alloys can overlap and the discrimination becomes a challenging problem. moreover, even finding a typical curve from replicated tests requires subjective judgement. in this paper   we used the so - called multi-@xmath0 approach based on the tsallis statistics in a classification engine to separate multiple polarization curve profiles of two stainless steels.   we collected 48 experimental polarization curves in aqueous chloride medium of two stainless steel types, with different resistance against localized corrosion.   multi-@xmath0 pattern analysis was then carried out on a wide potential range, from cathodic up to anodic regions.   an excellent classification rate was obtained, at a success rate of @xmath1, @xmath2, and @xmath3 for low ( cathodic ), high ( anodic ), and both potential ranges, respectively, using only @xmath4 of the original profile data.   these results show the potential of the proposed approach towards efficient, robust, systematic and automatic classification of highly non - linear profile curves.    profile pattern classification, polarization curve, tsallis entropy, multi-@xmath0 pattern analysis
we study the reaction of a globular star cluster to a time - varying tidal perturbation ( gravitational shock ) using self - consistent n - body simulations and address two questions.   first, to what extent is the cluster interior protected by adiabatic invariants.   second, how much further energy change does the postshock evolution of the cluster potential produce and how much does it affect the dispersion of stellar energies.   we introduce the _ adiabatic correction _ as ratio of the energy change, @xmath0, to its value in the impulse approximation. when the potential is kept fixed, the numerical results for the adiabatic correction for stars with orbital frequency @xmath1 can be approximated as @xmath2. for shocks with the characteristic duration of the order the half - mass dynamical time of the cluster, @xmath3, the exponent @xmath4. for more prolonged shocks, @xmath5,   the adiabatic correction is shallower, @xmath6.   when we allow for self - gravity and potential oscillations which follow the shock, the energy of stars in the core changes significantly, while the total energy of the system is conserved. paradoxically, the postshock potential fluctuations _ reduce _ the total amount of energy dispersion, @xmath7.   the effect is small but real and is due to the postshock energy change being statistically anti - correlated with the shock induced heating.   these results are to be applied to fokker - planck models of the evolution of globular clusters.
we present new _ spitzer space telescope _   observations of stars in the young ( @xmath05 myr ) @xmath1 velorum stellar cluster. combining optical and 2mass photometry  , we have selected 579 stars as candidate members of the cluster. with the addition of the spitzer mid - infrared data  , we have identified 5 debris disks around a - type stars, and 5 - 6 debris disks around solar - type stars, indicating that the strong radiation field in the cluster does not completely suppress the production of planetesimals in the disks of cluster members.   however, we find some evidence that the frequency of circumstellar primordial disks is lower, and the ir flux excesses are smaller than for disks around stellar populations with similar ages. this could be evidence for a relatively fast dissipation of circumstellar dust by the strong radiation field from the highest mass star(s ) in the cluster.   another possibility is that @xmath1 velorum stellar cluster is slightly older than reported ages and the the low frequency of primordial disks reflects the fast disk dissipation observed at @xmath05 myr.
we have calculated the electronic band structure of the ( 100 ) surface of the iii  v zinc blende semiconductor compounds, using the standard tight binding method and the surface green s function matching method.   we have found that the creation of the surface gives place to new states in the electronic structure : surface resonances and two dimensional bulk states.   the two dimensional bulk states are of the same character of those reported recently in cdte(100 ) [ phys. rev. *   50 *, 1980 ( 1994 ) ].   we analyze the states in the valence band region and compare with photoemission spectroscopy data.
radio observations of sn 1986e have shown a clear detection of emission at 6 cm wavelength about 8 months after optical discovery. combined with a number of new upper limits and a study of the possible models  , it appears that sn 1986e was probably a fairly normal type iil supernova, somewhat similar to sn 1980k, with radio emission at roughly expected levels.   this detection continues the correlation between radio detection and late time optical emission.
we establish the stable homotopy classification of elliptic pseudodifferential operators on manifolds with corners and show that the set of elliptic operators modulo stable homotopy is isomorphic to the @xmath0-homology group of some stratified manifold. by way of application,   generalizations of some recent results due to monthubert and nistor are given.
in the present paper, we have briefly reviewed sznajd s sociophysics model and its variants, and also we have proposed a simple sznajd like sociophysics model based on ising spin system in order to explain the time evaluation of resistance probability of a closed community against occupation. using a numerical method, we have shown that time evaluation of resistance probability of community has a non - exponential character which decays as stretched exponential independent of the number of soldiers in a one - dimensional model.   furthermore, it has been astonishingly found that our simple sociophysics model belongs to the same universality class with random walk process on the trapping space.   * keywords : * ising model ; politics ; random walk ; sociophysics ; sznajd model.
we present unprecedented high resolution h@xmath0 observations, obtained with the swedish 1-m solar telescope, that, for the first time, spatially and temporally resolve dynamic fibrils in active regions on the sun.   these jet - like features are similar to mottles or spicules in quiet sun.   we find that most of these fibrils follow almost perfect parabolic paths in their ascent and descent.   we measure the properties of the parabolic paths taken by 257 fibrils, and present an overview of the deceleration, maximum velocity, maximum length and duration, as well as their widths and the thickness of a bright ring that often occurs above dynamic fibrils.   we find that the observed deceleration of the projected path is typically only a fraction of solar gravity, and incompatible with a ballistic path at solar gravity.   we report on significant differences of fibril properties between those occurring above a dense plage region, and those above a less dense plage region where the magnetic field seems more inclined from the vertical.   we compare these findings to advanced numerical 2d radiative mhd simulations, and find that fibrils are most likely formed by chromospheric shock waves that occur when convective flows and global oscillations leak into the chromosphere along the field lines of magnetic flux concentrations.   detailed comparison of observed and simulated fibril properties shows striking similarities of the values for deceleration, maximum velocity, maximum length and duration.   we compare our results with observations of mottles and find that a similar mechanism is most likely at work in the quiet sun.
clusters of galaxies are revealing themselves as powerful sources of non thermal radiation in a wide range of wavelengths. in order to account for these multifrequency observations equipartition of cosmic rays ( crs ) with the thermal gas in clusters of galaxies   is often invoked.   this condition might suggest a dynamical role played by cosmic rays in the virialization of these large scale structures and is now testable through gamma ray observations.   we show here, in the specific case of the coma and virgo clusters, for which upper limits on the gamma ray emission exist, that equipartition implies gamma ray fluxes that are close or even in excess of the egret limit, depending on the adopted model of cr injection.   we use this bound to limit the validity of the equipartition condition.   we also show that, contrary to what claimed in previous calculations, the equipartition assumption implies gamma ray fluxes in the tev range which can be detectable even by currently operating gamma ray observatories if the injection cosmic ray spectrum is flatter than @xmath0.    epsf
one possible evolutionary scenario of the dense gluon system produced in an ultrarelativistic heavy ion collision is the bottom - up thermalization scenario, which describes the dynamics of the system shortly after the collision via the decay of originally produced hard gluons to soft ones through qcd branching processes.   the soft gluons form a thermal bath that subsequently reaches thermalization and/or equilibration.   there is a scaling solution to the bottom - up problem that interpolates between its early stage, which has a highly anisotropic gluon distribution, and its final stage of equilibration which occurs later.   such a solution depends on a single parameter, the so called momentum asymmetry parameter @xmath0. with this scaling solution,   the bottom - up scenario gets modified and the evolving parton system, referred to as the _ m_bottom - up parton system throughout this paper, is described by this modification.   the time evolution of the system in the original bottom - up ansatz is driven by the saturation scale, @xmath1. however, for the _ m_bottom - up we generalize the ansatz of the evolution by introducing two additional momentum scales, which give a thermalization time and temperature of the soft gluon bath somewhat different from those obtained when the _ m_bottom - up matches onto the final stage of the original bottom - up scenario.   relativistic heavy ion collisions, quark - gluon plasma, relativistic plasma, qcd in nuclear reactions, thermalization. 25.75.-q, 12.38.mh, 52.27.ny, 24.85.+p
we have made co(@xmath0 ) observations towards the hii region rcw 49 and its ionizing source, the rich stellar cluster westerlund 2, with the nanten2 sub - mm telescope.   these observations have revealed that two molecular clouds in velocity ranges of @xmath1 to @xmath2 km s@xmath3 and 11 to 21 km s@xmath3 respectively, show remarkably good spatial correlations with the _ spitzer _ irac mid - infrared image of rcw 49, as well a velocity structures indicative of localized expansion around the bright central regions and stellar cluster.   this strongly argues that the two clouds are physically associated with rcw 49.   we obtain a new kinematic distance estimate to rcw 49 and wd2 of @xmath4 kpc, based on the mean velocity and velocity spread of the associated gas.   we argue that acceleration of the gas by stellar winds from westerlund 2 is insufficient to explain the entire observed velocity dispersion of the molecular gas, and suggest a scenario in which a collision between the two clouds @xmath54 myrs ago may have triggered the formation of the stellar cluster.
collisionless shocks are loosely defined as shocks where the transition between pre - and post - shock states happens on a length scale much shorter than the collisional mean free path. in the absence of collision to enforce thermal equilibrium post - shock, electrons and ions need not have the same temperatures. while the acceleration of electrons for injection into shock acceleration processes to produce cosmic rays   has received considerable attention, the related problem of the shock heating of quasi - thermal electrons has been relatively neglected.    in this paper   we review that state of our knowledge of electron heating in astrophysical shocks, mainly associated with supernova remnants ( snrs ), shocks in the solar wind associated with the terrestrial and saturnian bowshocks, and galaxy cluster shocks.   the solar wind and snr samples indicate that the ratio of electron temperature, ( @xmath0 ) to ion temperature ( @xmath1 ) declines with increasing shock speed or alfvn mach number.   we discuss the extent to which such behavior can be understood via cosmic ray - generated waves in a shock precursor, which then subsequently damp by heating electrons. finally, we speculate that a similar mechanism may be at work for both solar wind and snr shocks.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
recently, different experiments on the transport through atomic - sized contacts made of ferromagnetic materials have produced contradictory results.   in particular, several groups have reported the observation of half - integer conductance quantization, which requires having full spin polarization and perfectly conducting channels.   motivated by these surprising results, we have studied theoretically the conductance of ideal atomic contact geometries of the ferromagnetic 3@xmath0 materials fe, co, and ni using a realistic tight - binding model.   our analysis shows that in the absence of magnetic domains, the @xmath0 bands of these transition metals play a key role in the electrical conduction. in the contact regime   this fact has the following important consequences for the three materials : ( i ) there are partially open conduction channels and therefore conductance quantization is not expected, ( ii ) the conductance of the last plateau is typically above @xmath1, ( iii ) both spin species contribute to the transport and thus there is in general no full current polarization, and ( iv ) both the value of the conductance and the current polarization are very sensitive to the contact geometry and to disorder. in the tunneling regime   we find that a strong current polarization can be achieved.
we show that the asymptotic growth rate for the minimal cardinality of a set of simple closed curves on a closed surface of genus @xmath0 which fill and pairwise intersect at most @xmath1 times is @xmath2 as @xmath3.   we then bound from below the cardinality of a filling set of systoles by @xmath4.   this illustrates that the topological condition that a set of curves pairwise intersect at most once is quite far from the geometric condition that such a set of curves can arise as systoles.
in this comment we discuss the problem of reconciling the linear efficiency of price returns with the long - memory of supply and demand.   we present new evidence that shows that efficiency is maintained by a liquidity imbalance that co - moves with the imbalance of buyer vs. seller initiated transactions. for example, during a period where there is an excess of buyer initiated transactions, there is also more liquidity for buy orders than sell orders, so that buy orders generate smaller and less frequent price responses than sell orders. at the moment a buy order is placed the transaction sign imbalance tends to dominate, generating a price impact.   however, the liquidity imbalance rapidly increases with time, so that after a small number of time steps it cancels all the inefficiency caused by the transaction sign imbalance, bounding the price impact. while the view presented by bouchaud et al. of a fixed and temporary bare price impact   is self - consistent and formally correct, we argue that viewing this in terms of a variable but permanent price impact provides a simpler and more natural view.   this is in the spirit of the original conjecture of lillo and farmer, but generalized to allow for finite time lags in the build up of the liquidity imbalance after a transaction.   we discuss the possible strategic motivations that give rise to the liquidity imbalance and offer an alternative hypothesis.   we also present some results that call into question the statistical significance of large swings in expected price impact at long times.
we analyze the phenomenological implications of introducing vector - like leptons on the higgs sector in the higgs triplet model.   we impose only a parity symmetry which disallows mixing between the new states and the ordinary leptons.   if the vector leptons are allowed to be relatively light, they enhance or suppress the decay rates of loop - dominated neutral higgs bosons decays @xmath0 and @xmath1, and affect their correlation.   an important consequence is that, for light vector leptons, the decay patterns of the the doubly - charged higgs boson will be altered, modifying the restrictions on their masses.
the paper shows that normally hyperbolic one - dimensional compact attractors of smooth dynamical systems are characterized by differential positivity, that is, the pointwise infinitesimal contraction of a smooth cone field.   the result is analog to the characterization of zero - dimensional hyperbolic attractors by differential stability, which is the pointwise infinitesimal contraction of a riemannian metric.   differential positivity, normal hyperbolicity, converse theorems.
the mass density of dust particles that form from asteroids and comets in the interplanetary medium of the solar system is, near 1au, comparable to the mass density of the solar wind.   it is mainly contained in particles of micrometer size and larger.   dust and larger objects are destroyed by collisions and sublimation and hence feed heavy ions into the solar wind and the solar corona.   small dust particles are present in large number and as a result of their large charge to mass ratio deflected by electromagnetic forces in the solar wind. for nano dust particles of sizes @xmath0 nm, recent calculations show trapping near the sun and outside from about 0.15 au ejection with velocities close to solar wind velocity.   the fluxes of ejected nano dust are detected near 1au with the plasma wave instrument onboard the stereo spacecraft.   though such electric signals have been observed during dust impacts before, the interpretation depends on several different parameters and data analysis is still in progress.
three dimensional electromagnetic gyrofluid simulations of the ideal ballooning mode blowout scenario for tokamak edge localized modes ( elms ) are presented.   special emphasis is placed on energetic diagnosis, examining changes in the growth rate in the linear, overshoot, and decay phases.   the saturation process is energy transfer to self generated edge turbulence which exhibits an ion temperature gradient ( itg ) mode structure.   convergence in the decay phase is found only if the spectrum reaches the ion gyroradius.   the equilibrium is a self consistent background whose evolution is taken into account.   approximately two thirds of the total energy in the edge layer is liberated in the blowout.   parameter dependence with respect to plasma pressure and the ion gyroradius is studied. despite the violent nature of the short - lived process  , the transition to nonlinearity is very similar to that found in generic tokamak edge turbulence.
random jitter in the soliton arrival time ( the gordon - haus effect ) is analyzed for solitons being solutions of the integrable modified nonlinear schrdinger equation.   it is shown that the mean square fluctuation of the soliton position depends on the soliton parameters which can be properly adjusted to suppress the gordon - haus jitter.    * the gordon - haus effect for modified nls solitons *    e.v.   doktorov and i.s.   kuten    b.i.   stepanov institute of physics + 68 f. skaryna ave.  , 220072 minsk, belarus
we summarize the main results of a mid - ir photometric survey with iso for a few nearby embedded clusters.   the sensitivity and spatial resolution of isocam provided a wonderful tool for studies of the youngest stellar clusters, which are still deeply embedded in their parent molecular clouds.   mid - ir photometry is found to be extremely efficient in finding all the young stellar objects ( ysos ) with ir excesses, i.e. mainly t  tauri stars surrounded by circumstellar disks and also some classi sources.   the spatial distribution of these sources is highly clustered and even sub - clustered, with a tendency of stronger concentration for the younger regions.   the improved samples of ir - excess ysos appear complete down to @xmath0 for the most nearby clusters.   this gives constraints on the mass functions well into the brown dwarf domain.   the first results show that the mass functions of these clusters are identical to the field star imf derived by kroupa et al.   ( 1993 ) with a flattening of the mass function at @xmath1.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
projected entangled pair states ( peps ) provide a framework for the construction of models where a single tensor gives rise to both hamiltonian and ground state wavefunction on the same footing.   a key problem is to characterize the behavior which emerges in the system in terms of the properties of the tensor, and thus of the hamiltonian. in this paper  , we consider peps models with @xmath0 on - site symmetry and study the occurence of long - range order and spontaneous symmetry breaking.   we show how long - range order is connected to a degeneracy in the spectrum of the peps transfer operator, and how the latter gives rise to spontaneous symmetry breaking under perturbations.   we provide a succinct characterization of the symmetry broken states in terms of the peps tensor, and find that using the symmetry broken states we can derive a local entanglement hamiltonian, thereby restoring locality of the entanglement hamiltonian for all gapped phases.
we construct a dark energy model where a scalar field non - minimally coupled to gravity plays the role of the dark component.   we compare cosmological consequences of this non - minimal coupling of the scalar field and gravity in the spirit of the dark energy paradigm in jordan and einstein frames.   some important issues such as phantom divide line crossing, existence of the bouncing solutions and the stability of the solutions are compared in these two frames.   we show that while a non - minimally coupled scalar field in the jordan frame is a suitable dark energy component with capability to realize phantom divide line crossing, its conformal transformation in the einstein frame has not this capability.   the conformal transformation from jordan frame to einstein frame transforms the equation of state parameter of the dark energy component to its minimal form with a redefined scalar field and in this case it is impossible to realize a phantom phase with possible crossing of the phantom divide line. + * pacs * : 98.80.-k, 98.80.cq + * key words * : scaler - tensor theories, dark energy models, bouncing solutions    0 mm 0 mm 0 mm 0 mm 0 mm 165 mm 220 mm.65 cm     +  and +   + _knozari@umz.ac.ir_ + _d.sadatian@umz.ac.ir_
this paper is part of a series describing the results from the _ australia telescope hubble deep field south _ ( athdfs ) survey obtained with the _ australia telescope compact array _ ( atca ).   this survey consists of observations at 1.4, 2.5, 5.2 and 8.7 ghz, all centred on the hubble deep field south.    here   we present the first results from the extended observing campaign at 1.4 ghz.   a total of 466 sources have been catalogued to a local sensitivity of @xmath0 ( 11 @xmath1jy rms ).   a source extraction technique is developed which : 1 ) successfully excludes spurious sources from the final source catalogues, and 2 ) accounts for the non - uniform noise in our image.   a source catalogue is presented and the general properties of the 1.4 ghz image are discussed.   we also present source counts derived from our athdfs 1.4 ghz catalogue.   particular attention is made to ensure the counts are corrected for survey incompleteness and systematic effects.   our counts are consistent with other surveys ( e.g. atesp, virmos, and phoenix deep field ), and we find, in common with these surveys, that the hdfn counts are systematically lower.
we studied the bouchaud - mzard(bm ) model, which was introduced to explain pareto s law in a real economy, on a random network. using `` adiabatic and independent '' assumptions  , we analytically obtained the stationary probability distribution function of wealth.   the results shows that wealth - condensation, indicated by the divergence of the variance of wealth, occurs at a larger @xmath0 than that obtained by the mean - field theory, where @xmath0 represents the strength of interaction between agents.   we compared our results with numerical simulation results and found that they were in good agreement.
a periodic variation in the pulse timings of the pulsating hot subdwarf b star cs 1246 was recently discovered via the o - c diagram and suggests the presence of a binary companion with an orbital period of two weeks  . fits to this phase variation, when interpreted as orbital reflex motion, imply cs 1246 orbits a barycenter 11 light - seconds away with a velocity of 16.6 km s@xmath0. using the goodman spectrograph on the soar telescope, we decided to confirm this hypothesis by obtaining radial velocity measurements of the system over several months.   our spectra reveal a velocity variation with amplitude, period, and phase in accordance with the o - c diagram predictions.   this corroboration demonstrates that the rapid pulsations of hot subdwarf b stars can be adequate clocks for the discovery of binary companions via the pulse timing method.
we obtained thermal equilibrium solutions for optically thin, two - temperature black hole accretion disks incorporating magnetic fields.   the main objective of this study is to explain the bright / hard state observed during the bright / slow transition of galactic black hole candidates.   we assume that the energy transfer from ions to electrons occurs via coulomb collisions.   bremsstrahlung, synchrotron, and inverse compton scattering are considered as the radiative cooling processes. in order to complete the set of basic equations, we specify the magnetic flux advection rate instead of @xmath0. we find magnetically supported ( low-@xmath1 ), thermally stable solutions. in these solutions,   the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling.   the low-@xmath1 solutions extend to high mass accretion rates ( @xmath2 ) and the electron temperature is moderately cool ( @xmath3 ).   high luminosities ( @xmath4 ) and moderately high energy cutoffs in the x - ray spectrum ( @xmath5 ) observed in the bright / hard state can be explained by the low-@xmath1 solutions.
a high - frequency survey of the galactic plane for radio pulsars is in progress, using the multibeam receiver on the 64-m parkes radiotelescope.   we describe the survey motivations, the observing plan and the inital results.   the survey is discovering many pulsars, more than 500 so far.   eight of the new pulsars are binary, one with a massive companion.   at least eight are young, with characteristic ages of less than 100 kyr.   two of these ( kaspi et al, this conference ) have surface dipole magnetic field strengths greater than any other known radio pulsar.   0= = 0 ! =!
i present a systematic study of all possible four leptons final states from @xmath0 collisions.   it is given a detailed account of fermion masses effects which are sizable since several collinear and @xmath1 channel enancements occur.   the effects of angular cuts on the final charged leptons are also discussed. to perform the computation   i have used the recently developed alpha algorithm ( and the resulting code ) for the automatic computation of scattering amplitudes.    //   = -1.0 cm = -2.0 cm    # 1#1
we present results from high - resolution radio and optical observations of pmn  j01340931, a gravitational lens with a unique radio morphology and an extremely red optical counterpart.   our data support the theory of keeton & winn ( 2003 ) : five of the six observed radio components are multiple images of a single quasar, produced by a pair of lens galaxies.   multi - frequency vlba maps show that the sixth and faintest component has a different radio spectrum than the others, confirming that it represents a second component of the background source rather than a sixth image.   the lens models predict that there should be additional faint images of this second source component, and we find evidence for one of the predicted images.   the previously - observed large angular sizes of two of the five bright components are not intrinsic ( which would have excluded the possibility that they are lensed images ), but are instead due to scatter broadening.   both the extended radio emission observed at low frequencies, and the intrinsic image shapes observed at high frequencies, can be explained by the lens models.   the pair of lens galaxies is marginally detected in hst images.   the differential extinction of the quasar images suggests that the extreme red color of the quasar is at least partly due to dust in the lens galaxies.
we present the results of our photometric and spectroscopic studies of the new eclipsing cataclysmic variable star 1rxs j180834.7 + 101041.   its spectrum exhibits double - peaked hydrogen and helium emission lines.   the doppler maps constructed from hydrogen lines show a nonuniform distribution of emission in the disk similar to that observed in ip peg.   this suggests that the object can be a cataclysmic variable with tidal density waves in the disk.   we have determined the component masses ( @xmath0 and @xmath1 ) and the binary inclination ( @xmath2 ) based on well - known relations between parameters for cataclysmic variable stars.   we have modeled the binary light curves and showed that the model of a disk with two spots is capable of explaining the main observed features of the light curves.
we investigate finite - size effects in quantum systems at first - order quantum transitions. for this purpose   we consider the one - dimensional @xmath0-state potts models which undergo a first - order quantum transition for any @xmath1, separating the quantum disordered and ordered phases with a discontinuity in the energy density of the ground state.   the low - energy properties around the transition show finite - size scaling, described by general scaling ansatzes with respect to appropriate scaling variables.   the size dependence of the scaling variables presents a particular sensitiveness to boundary conditions, which may be considered as a peculiar feature of first - order quantum transitions.
we report on a re - analysis of archival data from the very large array for a sample of ten long duration radio transients reported by bower and others.   these transients have an implied all - sky rate that would make them the most common radio transient in the sky and yet most have no quiescent counterparts at other wavelengths and therefore no known progenitor ( other than galactic neutron stars ).   we find that more than half of these transients are due to rare data artifacts.   the remaining sources have lower signal - to - noise ratio ( snr ) than initially reported by 1 to @xmath0.   this lowering of snr matters greatly since the sources are at the threshold.   we are unable to decisively account for the differences. by two orthogonal criteria one source appears to be a good detection.   thus the rate of long duration radio transients without optical counterparts is, at best, comparable to that of the class of recently discovered swiftj1644 + 57 nuclear radio transients.   we revisit the known and expected classes of long duration radio transients and conclude that the dynamic radio sky remains a rich area for further exploration.   informed by the experience of past searches for radio transients, we suggest that future surveys pay closer attention to rare data errors and ensure that a wealth of sensitive multi - wavelength data be available in advance of the radio observations and that the radio searches should have assured follow - up resources.
we present quantum maxwell - bloch equations ( qmbe ) for spatially inhomogeneous semiconductor laser devices.   the qmbe are derived from fully quantum mechanical operator dynamics describing the interaction of the light field with the quantum states of the electrons and the holes near the band gap. by taking into account field - field correlations and field - dipole correlations,   the qmbe include quantum noise effects which cause spontaneous emission and amplified spontaneous emission. in particular, the source of spontaneous emission is obtained by factorizing the dipole - dipole correlations into a product of electron and hole densities.   the qmbe are formulated for general devices, for edge emitting lasers and for vertical cavity surface emitting lasers, providing a starting point for the detailed analysis of spatial coherence in the near field and far field patterns of such laser diodes.   analytical expressions are given for the spectra of gain and spontaneous emission described by the qmbe.   these results are applied to the case of a broad area laser, for which the frequency and carrier density dependent spontaneous emission factor @xmath0 and the evolution of the far field pattern near threshold are derived.
with an expected ten - fold increase in luminosity in s - lhc, the radiation environment in the tracker volumes will be considerably harsher for silicon - based detectors than the already harsh lhc environment.   since 2006, a group of cms institutes, using a modified cms daq system, has been exploring the use of magnetic czochralski silicon as a detector element for the strip tracker layers in s - lhc experiments.   both p+/n-/n+ and n+/p-/p+ sensors have been characterized, irradiated with proton and neutron sources, assembled into modules, and tested in a cern beamline.   there have been three beam studies to date and results from these suggest that both p+/n-/n+ and n+/p-/p+ magnetic czochralski silicon are sufficiently radiation hard for the @xmath0 cm regions of s - lhc tracker volumes. the group has also explored the use of forward biasing for heavily irradiated detectors, and although this mode requires sensor temperatures less than -50@xmath1c, the charge collection efficiency appears to be promising.    magnetic czochralski silicon, current injected detector, sibt
we study a system of an elastic ball moving in the non - relativistic spacetime with a nontrivial causal structure produced by a wormhole - based time machine.   for such a system it is possible to formulate a simple model of the so - called `` grandfather paradox '' : for certain `` paradoxical '' initial conditions the standard straight trajectory of the ball would self - collide inconsistently.   we analyze globally consistent solutions of local equations of motion, namely, we find all trajectories with one self - collision.   it is demonstrated that all standard initial conditions have a consistent evolution, including those `` paradoxical '' ones, for which the inconsistent collision - free trajectory is superseded by a special consistent self - colliding trajectory.   moreover, it is shown that for a wide class of initial conditions more than one globally consistent evolution exist.   the nontrivial causal structure thus breaks the uniqueness of the classical theory even for locally deterministic physical laws.
we consider the effect of electron - electron interaction on the electron transport through a finite length single - mode quantum wire with reflectionless contacts.   the two - particle scattering events can not alter the electric current and therefore we study the effect of three - particle collisions. within the boltzmann equation framework  , we calculate corrections to the thermopower and conductance to the leading order in the interaction and in the length of wire @xmath0.   we check explicitly that the three - particle collision rate is identically zero in the case of several integrable interaction potentials. in the general ( non - integrable )   case, we find a positive contribution to the thermopower to leading order in @xmath0.   the processes giving rise to the correction involve electron states deep in the fermi sea.   therefore the correction follows an activation law with the characteristic energy of the order of the fermi energy for the electrons in the wire.
constructions of woven graph codes based on constituent block and convolutional codes are studied.   it is shown that within the random ensemble of such codes based on @xmath0-partite, @xmath0-uniform hypergraphs, where @xmath0 depends only on the code rate, there exist codes satisfying the varshamov - gilbert ( vg ) and the costello lower bound on the minimum distance and the free distance, respectively.   a connection between regular bipartite graphs and tailbiting codes is shown.   some examples of woven graph codes are presented. among them   an example of a rate @xmath1 woven graph code with @xmath2 based on heawood s bipartite graph and containing @xmath3 constituent rate @xmath4 convolutional codes with overall constraint lengths @xmath5 is given.   an encoding procedure for woven graph codes with complexity proportional to the number of constituent codes and their overall constraint length @xmath6 is presented.    * index terms*convolutional codes, girth, graphs, graph codes, hypergraphs, ldpc codes, tailbiting codes, woven codes.
we consider the steady - state thermoelectric transport through a vibrating molecular quantum dot that is contacted to macroscopic leads. for moderate electron - phonon interaction strength and comparable electronic and phononic timescales  , we investigate the impact of the formation of a local polaron on the thermoelectric properties of the junction.   we apply a variational lang - firsov transformation and solve the equations of motion in the kadanoff - baym formalism up to second order in the dot - lead coupling parameter.   we calculate the thermoelectric current and voltage for finite temperature differences in the resonant and inelastic tunneling regimes. for a near resonant dot level,   the formation of a local polaron can boost the thermoelectric effect because of the franck - condon blockade.   the line shape of the thermoelectric voltage signal becomes asymmetrical due to the varying polaronic character of the dot state and in the nonlinear transport regime, vibrational signatures arise.
implementation of basic local monte - carlo algorithms on ati graphics processing units ( @xmath0 ) is investigated.   the ising model and pure @xmath1 gluodynamics simulations are realized with the compute abstraction layer ( @xmath2 ) of ati stream environment using the metropolis and the heat - bath algorithms, respectively.   we present an analysis of both cal programming model and the efficiency of the corresponding simulation algorithms on gpu.   in particular, the significant performance speed - up of these algorithms in comparison with serial execution is observed.    _   keywords : _ monte carlo simulations, parallel computing, gpgpu
the modern science of networks has brought significant advances to our understanding of complex systems.   one of the most relevant features of graphs representing real systems is community structure, or clustering, i. e. the organization of vertices in clusters, with many edges joining vertices of the same cluster and comparatively few edges joining vertices of different clusters.   such clusters, or communities, can be considered as fairly independent compartments of a graph, playing a similar role like, e. g., the tissues or the organs in the human body.   detecting communities is of great importance in sociology, biology and computer science, disciplines where systems are often represented as graphs.   this problem is very hard and not yet satisfactorily solved, despite the huge effort of a large interdisciplinary community of scientists working on it over the past few years.   we will attempt a thorough exposition of the topic, from the definition of the main elements of the problem, to the presentation of most methods developed, with a special focus on techniques designed by statistical physicists, from the discussion of crucial issues like the significance of clustering and how methods should be tested and compared against each other, to the description of applications to real networks.   = 1
in an attempt to look for a viable mechanism leading to a present - day accelerated expansion, we investigate the possibility that the observed cosmic speed up may be recovered in the framework of the rastall s theory, relying on the non - conservativity of the stress - energy tensor, i.e. @xmath0.   we derive the modified friedmann equations and show that they correspond to cardassian - like equations.   we also show that, under suitable assumptions on the equation of state of the matter term sourcing the gravitational field, it is indeed possible to get an accelerated expansion, in agreement with the hubble diagram of both type ia supernovae ( sneia ) and gamma ray bursts ( grbs ). unfortunately, to achieve such a result one has to postulate a matter density parameter much larger than the typical @xmath1 value inferred from cluster gas mass fraction data.   # 1 # 1 # 1 # 1 # 1 # 1 # 1`#1 `
we study the in - gap states of the quantum dot hybridized with one conducting and another superconducting electrode.   proximity effect suppresses the electronic states in the entire subgap regime @xmath0, where @xmath1 denotes the energy gap of a superconductor.   the andreev scattering mechanism can induce, however, some in - gap states of a line - broadening ( inverse life - time ) controlled by a hybridization of the quantum dot with a normal electrode.   we show that the number of such andreev bound states is substantially dependent on a competition between the coulomb repulsion and the induced on - dot pairing.   we discuss signatures of these in - gap states in the tunneling conductance, especially in a low - bias regime.
we consider a gauge inflation model in the simplest orbifold @xmath0 with the minimal non - abelian @xmath1 hidden sector gauge symmetry.   the inflaton potential is fully radiatively generated solely by gauge self - interactions.   following the virtue of gauge inflation idea, the inflaton, a part of the five dimensional gauge boson, is automatically protected by the gauge symmetry and its potential is stable against quantum corrections.   we show that the model perfectly fits the recent cosmological observations, including the recent wmap 5-year data, in a wide range of the model parameters. in the perturbative regime of gauge interactions ( @xmath2 ) with the moderately compactified radius ( @xmath3 ) the anticipated magnitude of the curvature perturbation power spectrum and the value of the corresponding spectral index   are in perfect agreement with the recent observations.   the model also predicts a large fraction of the gravitational waves, negligible non - gaussianity, and high enough reheating temperature.   snutp 07 - 013    1.5 cm    0.5 cm    1.2 cm
the high energy neutrino cross section is a crucial ingredient in the calculation of the event rate in high energy neutrino telescopes.   currently there are several approaches which predict different behaviours for its magnitude for ultrahigh energies. in this paper   we present a comparison between the predictions based on linear dglap dynamics, non - linear qcd and in the imposition of a froissart - like behaviour at high energies.   in particular, we update the predictions based on the color glass condensate, presenting for the first time the results for @xmath0 using the solution of the running coupling balitsky - kovchegov equation.   our results demonstrate that the current theoretical uncertainty for the neutrino - nucleon cross section reaches a factor three for neutrinos energies around @xmath1 gev and increases to a factor five for @xmath2 gev.
we present the results of point - contact spectroscopy measurements in polycrystalline rusr@xmath0gdcu@xmath0o@xmath1 samples previously characterized from both the structural and the electrical point of view. ac susceptibility and resistivity measurements, as well as sem and optical microscopy,   indicate that the polycrystalline material is made up of small, weakly connected grains.   possibly because of this morphology, point - contact measurements turned out to be rather difficult.   best reproducibility of the conductance curves was achieved in point contacts obtained by pressing au or pt - ir tips on the surface of the samples.   the low - temperature conductance curves reproducibly show a clear zero - bias cusp that might be interpreted as due to andreev reflection at the normal metal - superconductor interface in the case where the superconducting order parameter has a pure @xmath2-wave symmetry - even though alternative explanations can not be ruled out. in this paper   we show that these curves can indeed be fitted, in the framework of the generalised btk model, by using pure @xmath2-wave symmetry and a gap of the order of 6 mev  . finally, we present the temperature dependence of the conductance curves from 4.2 k up to the critical temperature of the junctions.
we study by means of density - functional calculations the role of lateral surface reconstructions in determining the electrical properties of @xmath0 silicon nanowires.   the different lateral reconstructions are explored by relaxing all the nanowires with crystalline bulk silicon structure and all possible ideal facets that correspond to an average diameter of 1.5  nm.   we show that the reconstruction induces the formation of ubiquitous surface states that turn the wires into semi - metallic or metallic.
dwarf and low surface brightness galaxies are ideal objects to test modified newtonian dynamics ( mond ), because in most of these galaxies the accelerations fall below the threshold below where mond supposedly applies.   we have selected from the literature a sample of 27 dwarf and low surface brightness galaxies.   mond is successful in explaining the general shape of the observed rotation curves for roughly three quarters of the galaxies in the sample presented here.   however, for the remaining quarter, mond does not adequately explain the observed rotation curves.   considering the uncertainties in distances and inclinations for the galaxies in our sample, a small fraction of poor mond predictions is expected and is not necessarily a problem for mond.   we have also made fits taking the mond acceleration constant, @xmath0, as a free parameter in order to identify any systematic trends.   we find that there appears to be a correlation between central surface brightness and the best - fit value of @xmath0, in the sense that lower surface brightness galaxies tend to have lower @xmath0.   however, this correlation depends strongly on a small number of galaxies whose rotation curves might be uncertain due to either bars or warps. without these galaxies, there is less evidence of a trend, but the average value we find for @xmath1 cm s@xmath2 is somewhat lower than derived from previous studies.   such lower fitted values of @xmath0 could occur if external gravitational fields are important.
we have studied the extended hubbard model with pair hopping in the atomic limit for arbitrary electron density and chemical potential.   the hamiltonian considered consists of ( i )  the effective on - site interaction @xmath0 and ( ii )  the intersite charge exchange interactions @xmath1, determining the hopping of electron pairs between nearest - neighbour sites.   the model can be treated as a simple effective model of a  superconductor with very short coherence length in which electrons are localized and only electron pairs have possibility of transferring.   the phase diagrams and thermodynamic properties of this model have been determined within the variational approach, which treats the on - site interaction term exactly and the intersite interactions within the mean - field approximation.   we have also obtained rigorous results for a  linear chain ( ) in the ground state. moreover, at some results derived within the random phase approximation ( and the spin - wave approximation ) for and lattices and within the low density expansions for lattices are presented.   our investigation of the general case ( as a function of the electron concentration @xmath2 and as a function of the chemical potential @xmath3 ) shows that, depending on the values of interaction parameters, the system can exhibit not only the homogeneous phases : superconducting ( ss ) and nonordered ( no ), but also the phase separated states ( ps : ). the system considered exhibits interesting multicritical behaviour including tricritical points
in this paper we present a determinant quantum monte carlo study of the two dimensional hubbard model with random site disorder.   we show that, as in the case of bond disorder, the system undergoes a transition from an anderson insulating phase to a metallic phase as the on - site repulsion @xmath0 is increased beyond a critical value @xmath1  . however, there appears to be no sharp signal of this metal - insulator transition in the screened site energies.   we observe that, while the system remains metallic for interaction values up to twice @xmath1, the conductivity is maximal in the metallic phase just beyond @xmath1, and decreases for larger correlation.
we present maps of seven sources selected from @xcite in sio ( j=8 - 7 ) and hco@xmath0 and h@xmath1co@xmath0 ( j=4 - 3 ) which were obtained using harp - b on the james clerk maxwell telescope.   we find that four out of our seven sources have infall signatures based on their hco@xmath0 emission profiles. from our maps,   we have determined the extent of both the outflowing and infalling regions towards these sources, and constrained the amount of infalling and outflowing mass as well as the mass infall rate for each massive star forming region. from our sio observations  , we estimate the source luminosity required to shock the surroundings of these massive star forming regions and find luminosities similar to those of the hii regions themselves.   we find that the ratio between our infall and outflow masses is less than one, suggesting high mass entrainment rates in the molecular outflows.   we also find that the large scale molecular infall rate towards g10.6 - 0.4 is comparable to the small scale molecular infall rate found in previous studies.
in this second paper in our series, we continue to test primordial scenarios of globular cluster formation which predict that globular clusters formed in the early universe in the potential of dark matter minihalos. in this paper   we use high - resolution @xmath0-body simulations to model tidal stripping experienced by primordial dark - matter dominated globular clusters in the static gravitational potential of the host dwarf galaxy.   we test both cuspy navarro - frenk - white ( nfw ) and flat - core burkert models of dark matter halos.   our primordial globular cluster with an nfw dark matter halo survives severe tidal stripping, and after 10 orbits is still dominated by dark matter in its outskirts.   our cluster with burkert dark matter halo loses almost all its dark matter to tidal stripping, and starts losing stars at the end of our simulations.   the results of this paper reinforce our conclusion in paper  i that current observations of globular clusters are consistent with the primordial picture of globular cluster formation.
we reconsider correlations among the spectral peak energy ( @xmath0 ), 1-second peak luminosity ( @xmath1 ) and isotropic energy ( ), using the database constructed by @xcite which consists of 109 gamma - ray bursts ( grbs ) whose redshifts are known and @xmath0, @xmath1 and are well determined. we divide the events into two groups by their data quality. one ( gold data set ) consists of grbs with peak energies determined by the band model with four free parameters.   on the other hand, grbs in the other group ( bronze data set ) have relatively poor energy spectra so that their peak energies were determined by the band model with fixed spectral index ( i.e. three free parameters ) or by the cut - off power law ( cpl ) model with three free parameters. using only the gold data set we found the intrinsic dispersion in @xmath2 ( @xmath3 ) is 0.13 and 0.22 for correlation ( @xmath4 ) and correlation, respectively.   we also find that grbs in the bronze data set have systematically larger @xmath0 than expected by the correlations constructed with the gold data set.   this means that the intrinsic dispersion of correlations among @xmath0, @xmath1, and of grbs depends on the quality of data set. at present, using correlation with gold data set, we would be able to determine the luminosity distance with @xmath5 error, which might be useful to determine the nature of the dark energy at high redshift @xmath6.
a few approximate schemes to solve the hedin equations @xcite self - consistently introduced in ( phys. rev.   b 94, 155101 ( 2016 ) ) are explored and tested for 3d electron gas at metallic densities.   we calculate one electron spectra, dielectric properties, compressibility, and correlation energy.   considerable reduction in the calculated band width ( as compared to the self consistent gw result ) has been found when vertex correction was used for both the polarizability and the self energy. generally, it is advantageous to obtain the diagrammatic representation of the polarizability from the definition of this quantity as a functional derivative of electronic density with respect to the total field ( external plus induced ). for the self energy,   the first order vertex correction seems to be sufficient for the range of densities considered. whenever it is possible, we compare the accuracy of our vertex - corrected schemes with the accuracy of the self - consistent quasi - particle gw approximation ( qsgw ), which is less expensive computationally.   we show that qsgw approach performs poorly and we relate this poor performance with inaccurate description of the screening in the qsgw method ( with an error comprising a factor 2 - 3 in the physically important range of momenta ).
we present predictions for numerous statistics related to the presence of voids in the distribution of galaxies in a cold dark matter model of structure formation using a semi - analytic model of galaxy formation.   our study is able to probe galaxies with masses as low as @xmath0 corresponding to absolute magnitudes of @xmath1 and @xmath2.   we quantify the void and underdense probability functions, distributions of nearest neighbour distances and void sizes and compute the density profiles of voids.   these results are contrasted with the expectations for dark matter ( and the difference examined in terms of the galaxy / dark matter biasing relation ) and are compared to analytic predictions and observational data where available.   the predicted void probability functions are consistent with those measured from the center for astrophysics redshift surveys given the rather large uncertainties in this relatively small ( for studies of voids ) observational sample.   the size of the observational sample is too small to probe the bias between galaxies and dark matter that we predict.   we also examine the predicted properties of galaxies living within voids and contrast these with the general galaxy population.   our predictions are aimed at forthcoming large galaxy redshift surveys which should for the first time provide statistically accurate measures of the void population.   + * key words : * galaxies : statistics, cosmology : theory, dark matter, large - scale structure of universe
we use the co band at @xmath0 m to constrain the populations of young stars in the central regions of seyfert galaxies.   we report new co band spectroscopy of 46 seyfert galaxies. in most cases,   the observed co indices appear diluted by the presence of a non - stellar component ( most likely, warm dust surrounding the active nucleus ).   we used @xmath1 aperture photometry to estimate the non - stellar contribution at @xmath2.   we successfully corrected the co band for the dilution for 16 galaxies which were not dominated by the non - stellar component. comparing with co indices measured in elliptical and purely starbursting galaxies  , we find no evidence for strong starbursts in the majority of these galaxies.
we have studied the zero - temperature statistics of the charge transfer between the two edges of quantum hall liquids of, in general, different filling factors, @xmath0, with @xmath1, forming mach - zehnder interferometer.   general expression for the cumulant generating function in the large - time limit is obtained for symmetric interferometer with equal propagation times along the two edges between the contacts and constant bias voltage.   the low - voltage limit of the generating function can be interpreted in terms of the regular poisson process of electron tunneling, while its leading large - voltage asymptotics is proven to coincide with the solution of kinetic equation describing quasiparticle transitions between the @xmath2 states of the interferometer with different effective flux through it, where @xmath3. for @xmath4,   this dynamics reflects both the fractional charge @xmath5 and the fractional statistical angle @xmath6 of the tunneling quasiparticles.   explicit expressions for the second ( shot noise ) and third cumulants are obtained, and their voltage dependence is analyzed.
there is more than @xmath0 deviation between the experimental and theoretical results of the muon @xmath1.   this suggests that some of the susy particles have a mass of order 100 gev.   we study searches for those particles at the lhc with particular attention to the muon @xmath1.   in particular, the recent results on the searches for the non - colored susy particles are investigated in the parameter region where the muon @xmath1 is explained.   the analysis is independent of details of the susy models.   future prospects of the collider searches are also discussed.   ut1310    * muon @xmath1 vs lhc in supersymmetric models *.75 in    motoi endo, koichi hamaguchi, + sho iwamoto   , takahiro yoshinaga    0.25 in    _ department of physics, the university of tokyo, tokyo 1130033, japan _   .5 in
after confirmation of the presence of a hard x - ray excess with respect to the thermal emission in the coma cluster from two independent observations, obtained using the phoswich detection system onboard, we present in this _ letter _ also for abell 2256 the results of two observations performed with a time interval of about 2.5 yr. in both spectra a non thermal excess is present at a confidence level of @xmath0 and @xmath1, respectively. the combined spectrum obtained by adding up the two spectra allows to measure an excess at the level of @xmath2 4.8@xmath3 in the 2080 kev energy range.   the x - ray flux is in agreement with the published value of the first observation ( fusco - femiano ) and with that measured by a _ rossi x - ray timing explorer _ observation ( rephaeli & gruber ).
the approach to the ergodic limit in monte carlo simulations is studied using both analytic and numerical methods. with the help of a stochastic model, a metric   is defined that enables the examination of a simulation in both the ergodic and non - ergodic regimes. in the non - ergodic regime,   the model implies how the simulation is expected to approach ergodic behavior analytically, and the analytically inferred decay law of the metric allows the monitoring of the onset of ergodic behavior.   the metric is related to previously defined measures developed for molecular dynamics simulations, and the metric enables the comparison of the relative efficiencies of different monte carlo schemes.   applications to lennard - jones 13-particle clusters are shown to match the model for metropolis, j - walking and parallel tempering based approaches.   the relative efficiencies of these three monte carlo approaches are compared, and the decay law is shown to be useful in determining needed high temperature parameters in parallel tempering and j - walking studies of atomic clusters.    *   pacs * numbers : 05.10.ln, 02.70.lq    -30pt 0.0 in = 18.2 cm = 58 = -.35 in = -.3 in    specialpagefalse evenfoot oddfoot @page>1 j. p. neirotti, d. l. freeman. and   j. d. doll@page=1    * abstract *    2
using observations obtained with the wide field camera 3 ( wfc3 ) on board the _ hubble space telescope _   ( hst ), we have studied the properties of the stellar populations in the central regions of 30dor, in the large magellanic cloud. the observations clearly reveal the presence of considerable differential extinction across the field.   we characterise and quantify this effect using young massive main sequence stars to derive a statistical reddening correction for most objects in the field.   we then search for pre - main sequence ( pms ) stars by looking for objects with a strong ( @xmath0 ) h@xmath1 excess emission and find about 1150 of them over the entire field.   comparison of their location in the hertzsprung   russell diagram with theoretical pms evolutionary tracks for the appropriate metallicity reveals that about one third of these objects are younger than @xmath2myr, compatible with the age of the massive stars in the central ionising cluster r136, whereas the rest have ages up to @xmath3myr, with a median age of @xmath4myr.   this indicates that star formation has proceeded over an extended period of time, although we can not discriminate between an extended episode and a series of short and frequent bursts that are not resolved in time.   while the younger pms population preferentially occupies the central regions of the cluster, older pms objects are more uniformly distributed across the field and are remarkably few at the very centre of the cluster.   we attribute this latter effect to photoevaporation of the older circumstellar discs caused by the massive ionising members of r136.
in an attempt to characterize the distribution of forms and shapes of nodal domains in wave functions, we define a geometric parameter - the ratio @xmath0 between the area of a domain and its perimeter, measured in units of the wavelength @xmath1. we show that the distribution function @xmath2 can distinguish between domains in which the classical dynamics is regular or chaotic. for separable surfaces,   we compute the limiting distribution, and show that it is supported by an interval, which is independent of the properties of the surface. in systems which are chaotic, or in random - waves, the area - to - perimeter distribution has substantially different features which we study numerically.   we compare the features of the distribution for chaotic wave functions with the predictions of the percolation model to find agreement, but only for nodal domains which are big with respect to the wavelength scale.   this work is also closely related to, and provides a new point of view on isoperimetric inequalities.
we study resistivity temperature dependence of a three dimensional metamagnet near the metamagnet phase transition point in the case when magnetic structure tends to split into regions with high and low magnetization.   we show that in the case of weak pinning the spin relaxation time of domain wall is much larger than that of the volume spin fluctuations.   this opens a temperature range where resistivity temperature dependence is determined by scattering of conducting electrons by the domain wall fluctuations.   we show that it leads to quasi - linear low temperature dependence of resistivity.
we investigate the dynamics of a wave packet in a parity - breaking one - dimensional periodic potential slowly varied in time and perturbed by a linear potential.   parity is broken by considering an asymmetric double well per unit cell. by comparing the prediction of the semiclassical dynamics with the full schrdinger solution  , we show that bloch oscillations are strongly affected by anomalous velocity corrections related to berry s phase.   we characterize how these effects depend on the degree of parity breaking of the potential and on the modulation parameters.   we also discuss how to measure the effects of the anomalous velocity in current experiments with non - interacting bose - einstein condensates in bichromatic optical lattices, under the effect of gravity.
we study the cohomology of the massless brst complex of the type iib pure spinor superstring in flat space. in particular, we find that the cohomology at the ghost number three is nontrivial and transforms in the same representation of the supersymmetry algebra as the solutions of the linearized classical supergravity equations.   modulo some finite dimensional spaces, the ghost number three cohomology is the same as the ghost number two cohomology  . we also comment on the difference between the naive and semi - relative cohomology, and the role of b - ghost.   * @xmath0 + @xmath0 + vertex operators of ghost number three in type iib supergravity *   +   +
blazars with redshifts @xmath0 are likely candidates for detection at energies in the range 300  gev  50  tev with @xmath1erenkov telescopes and scintillator arrays.   we present @xmath2-ray flux predictions for a sample of 15 nearby flat - spectrum radio sources fitting the proton blazar model of mannheim ( 1993a ) to their observed broad - band spectral energy distributions. at high energies, we use fluxes or flux limits measured by rosat, cgro and the whipple observatory to constrain their spectra.   we take into account absorption of the @xmath2-rays by pair production with low energy photons of the diffuse infrared - to - optical photon background produced by galaxies ( cosmic absorption ) and with low energy synchrotron photons of the blazar radiation field ( internal absorption ).   typically, the theoretical spectra decrease much faster above tev ( photon index @xmath3 ) than between gev and tev ( @xmath4 ) owing to internal absorption.   + the predicted fluxes are confronted with flux limits in the 20 - 50  tev energy range obtained by the _ high energy gamma ray astronomy _ ( hegra ) experiment. without cosmic absorption,   the fluxes are about equal to the current sensitivity of hegra  . improved @xmath2/hadron separation techniques could render a detection by hegra possible, if cosmic absorption by the far - infrared background at wavelengths @xmath5  @xmath6 m is not exceedingly strong.
using a continuum bead - spring monte carlo model, we study the anomalous diffusion dynamics of a self - avoiding tethered membrane by means of extensive computer simulations.   we focus on the subdiffusive stochastic motion of the membrane s central node in the regime of flat membranes at temperatures above the membrane folding transition. while at times, larger than the characteristic membrane relaxation time @xmath0, the mean - square displacement of the center of mass of the sheet, @xmath1, as well as that of its central node, @xmath2, show the normal rouse diffusive behavior with a diffusion coefficient @xmath3 scaling as @xmath4 with respect to the number of segments @xmath5 in the membrane, for short times @xmath6 we observe a _ multiscale dynamics _ of the central node, @xmath7, where the anomalous diffusion exponent @xmath8 changes from @xmath9 to @xmath10, and then to @xmath11, before diffusion turns eventually to normal. by means of simple scaling arguments   we show that our main result, @xmath12, can be related to particular mechanisms of membrane dynamics which involve different groups of segments in the membrane sheet.   a comparative study involving also linear polymers demonstrates that the diffusion coefficient of self - avoiding tethered membranes, containing @xmath5 segments, is three times smaller than that of linear polymer chains with the same number of segments.
we report the measurement of the deca - heptuplet @xmath0-partial - wave scattering length @xmath1 of two bosonic isotopes of the highly magnetic element, dysprosium : @xmath2 for @xmath3dy and @xmath4 for @xmath5dy, where @xmath6 is the bohr radius.   the scattering lengths are determined by the cross - dimensional relaxation of ultracold gases of these dy isotopes at temperatures above quantum degeneracy. in this temperature regime,   the measured rethermalization dynamics can be compared to simulations of the boltzmann equation using a direct - simulation monte carlo ( dsmc ) method employing the anisotropic differential scattering cross section of dipolar particles.
a thin gaseous disk has often been investigated in the context of various phenomena in galaxies, which point to the existence of starburst rings and dense circumnuclear molecular disks.   the effect of self - gravity of the gas in the @xmath0 disk can be important in confronting observations and numerical simulations in detail. for use in such applications, a new method for the calculation of the gravitational force of a @xmath0 disk is presented. instead of solving the complete potential function problem  , we calculate the force in infinite planes in cartesian and polar coordinates by a reproducing kernel method. under the limitation of a @xmath0 disk  , we specifically represent the force as a double summation of a convolution of the surface density and a fundamental kernel and employ a fast fourier transform technique. in this method  , the entire computational complexity can be reduced from @xmath1 to @xmath2, where @xmath3 is the number of zones in one dimension.   this approach does not require softening.   the proposed method is similar to a spectral method, but without the necessity of imposing a periodic boundary condition.   we further show this approach is of near second order accuracy for a smooth surface density in a cartesian coordinate system.
some years ago, luck proposed a relevance criterion for the effect of aperiodic disorder on the critical behaviour of ferromagnetic ising systems. in this article, we show how luck s criterion can be derived within an exact renormalisation scheme for ising quantum chains with coupling constants modulated according to substitution rules.   luck s conjectures for this case are confirmed and refined. among other outcomes,   we give an exact formula for the correlation length critical exponent for arbitrary two - letter substitution sequences with marginal fluctuations of the coupling constants.   * aperiodic ising quantum chains *    joachim hermisson@xmath0, uwe grimm@xmath1  and  michael baake@xmath0    @xmath0institut fr theoretische physik, universitt tbingen, auf der morgenstelle 14, d72076 tbingen, germany    @xmath1institut fr physik, technische universitt chemnitz, d09107 chemnitz, germany
54.8pt 54.8pt the magnetic behaviour of nanoparticles of antiferromagnetic artificial ferritin has been investigated by @xmath0fe mssbauer absorption spectroscopy and magnetization measurements, in the temperature range 2.5k-250k and with magnetic fields up to 7 t.   samples containing nanoparticles with an average number of @xmath0fe atoms ranging from 400 to 2500 were studied. by analysing the magnetic susceptibility and zero field mssbauer data,   the anisotropy energy per unit volume is found, in agreement with some of the earlier studies, to have a value typical for ferric oxides, i.e. a few 10@xmath1ergs/@xmath2. by comparing the results of the two experimental methods at higher fields,   we show that, contrary to what is currently assumed, the uncompensated magnetisation of the ferritin cores in the superparamagnetic regime does not follow a langevin law. for magnetic fields below the spin - flop field  , we propose an approximate law for the field and temperature variation of the uncompensated magnetization, which was early evoked by nel but has so far never been applied to real antiferromagnetic systems.   more generally, this approach should apply to randomly oriented antiferromagnetic nanoparticles systems with weak uncompensated moments.   pacs : 75.50 tt ; 75.50 ee ; 76.80 + y    epsf    2
we present a new approach to the minimum - cost integral flow problem for small values of the flow.   it reduces the problem to the tests of simple multi - variable polynomials over a finite field of characteristic two for non - identity with zero. in effect  , we show that a minimum - cost flow of value @xmath0 in a network with @xmath1 vertices, a sink and a source, integral edge capacities and positive integral edge costs polynomially bounded in @xmath1 can be found by a randomized pram, with errors of exponentially small probability in @xmath2 running in @xmath3 time and using @xmath4 processors.   thus, in particular, for the minimum - cost flow of value @xmath5 we obtain an @xmath6 algorithm.
this is the summary report of the top quark kinematics working group prepared for snowmass 2013.   we study theoretical predictions for top pair differential distributions, in both boosted and un - boosted regimes, and present an overview of uncertainties and prospects for top spin correlations.   we study the prospects for measuring the inclusive sm top pair production asymmetry @xmath0 at lhc 14 as a function of systematic error, and show that some improvement over current systematic uncertainties, as customarily handled, is required for observing a sm - size asymmetry.   cuts on top pair invariant mass and rapidity do not substantially alter this conclusion.   we summarize the conclusions of contributed studies on alternate lhc measurements of the @xmath1 production asymmetry, in @xmath2jet final states and in forward top production at lhcb, both of which show good prospects for observing sm - size asymmetries in 50 fb@xmath3 of data at lhc14.   * kinematics of top quark final states : + a snowmass white paper *    andreas jung@xmath4, markus schulze@xmath5, and jessie shelton@xmath6 + @xmath7 _ fermilab, dab5 - ms 357, + p.o.   box 500, batavia, il, 60510, usa _   + @xmath8 _ high energy physics division, + argonne national laboratory, argonne, il 60439, usa   _   + @xmath9 _   center for the fundamental laws of nature, + harvard university, cambridge, ma 02138, usa _   +   + t.  schwarz, s.  berge, s.  westhoff, and v.  coco ( for the lhcb
we study the weak lefschetz property and the hilbert function of level artinian monomial almost complete intersections in three variables.   several such families are shown to have the weak lefschetz property if the characteristic of the base field is zero or greater than the maximal degree of any minimal generator of the ideal.   two of the families have an interesting relation to tilings of hexagons by lozenges.   this lends further evidence to a conjecture by migliore, mir - roig, and the second author. finally, using our results about the weak lefschetz property,   we show that the hilbert function of each level artinian monomial almost complete intersection in three variables is peaked strictly unimodal.
we report the discovery of @xmath0-ray emission from the circinus galaxy using the large area telescope ( lat ) onboard the _ fermi gamma - ray space telescope_. circinus is a nearby ( @xmath1 mpc ) starburst with a heavily obscured seyfert - type active nucleus, bipolar radio lobes perpendicular to the spiral disk, and kpc - scale jet - like structures.   our analysis of 0.1100 gev events collected during 4 years of lat observations reveals a significant ( @xmath2 ) excess above the background.   we find no indications of variability or spatial extension beyond the lat point - spread function. a power - law model used to describe the @xmath3gev @xmath0-ray spectrum yields a flux of @xmath4ph@xmath5s@xmath6 and photon index @xmath7, corresponding to an isotropic @xmath0-ray luminosity of @xmath8ergs@xmath6.   this observed @xmath0-ray luminosity exceeds the luminosity expected from cosmic - ray interactions in the interstellar medium and inverse compton radiation from the radio lobes.   thus the origin of the gev excess requires further investigation.   
this paper presents a comparative evaluation among the systems that participated in the spanish and english lexical sample tasks of senseval-2.   the focus is on pairwise comparisons among systems to assess the degree to which they agree, and on measuring the difficulty of the test instances included in these tasks.
far - off - resonant pulsed laser fields produce negligible excitation between two atomic states but may induce considerable phase shifts.   the acquired phases are usually calculated by using the adiabatic - elimination approximation.   we analyze the accuracy of this approximation and derive the conditions for its applicability to the calculation of the phases.   we account for various sources of imperfections, ranging from higher terms in the adiabatic - elimination expansion and irreversible population loss to couplings to additional states.   we find that, as far as the phase shifts are concerned, the adiabatic elimination is accurate only for a very large detuning.   we show that the adiabatic approximation is a far more accurate method for evaluating the phase shifts, with a vast domain of validity ; the accuracy is further enhanced by superadiabatic corrections, which reduce the error well below @xmath0.   moreover, owing to the effect of adiabatic population return, the adiabatic and superadiabatic approximations allow one to calculate the phase shifts even for a moderately large detuning, and even when the peak rabi frequency is larger than the detuning ; in these regimes the adiabatic elimination is completely inapplicable.   we also derive several exact expressions for the phases using exactly soluble two - state and three - state analytical models.
we show that the widely used homotopy method for solving fixpoint problems, as well as the harsanyi - selten equilibrium selection process for games, are -complete to implement. extending our result for the harsanyi - selten process  , we show that several other homotopy - based algorithms for finding equilibria of games are also -complete to implement  . a further application of our techniques yields the result that it is -complete to compute any of the equilibria that could be found via the classical lemke - howson algorithm, a complexity - theoretic strengthening of the result in @xcite.   these results show that our techniques can be widely applied and suggest that the -completeness of implementing homotopy methods is a general principle.   game theory, computational complexity
x - ray unabsorbed seyfert 2 galaxies appear to have x - ray absorption column densities that are too low ( @xmath0 @xmath1 ) to explain the absence of broad emission lines in their optical spectra, challenging the standard agn unification model. in this paper   we report suzaku exposure on the x - ray unabsorbed seyfert 2 galaxy iras f01475 - 0740, in which a hidden broad line region was detected through spectropolarimetric observation.   the x - ray data show rapid and significant variations on time scales down to 5 ks, indicating that we are viewing its central engine directly.   a newly obtained optical spectrum and previous optical / x - ray data suggest that state transition is unlikely in this source.   these make iras f01475 - 0740  a very peculiar x - ray unabsorbed seyfert 2 galaxy which can only be explained by absorption from materials with abnormally high dust - to - gas ratio ( by a factor of @xmath2 4 larger than galactic ).   this is in contrast to most agns, which typically show dust - to - gas ratios 3  100 times lower than the galactic.
quantum secure communication provides a new way for protecting the security of information. as an important component of quantum secure communication, remote state preparation ( rsp )   can securely transmit a quantum state from a sender to a remote receiver.   the existence of quantum noise severely affects the security and reliability of quantum communication system. in this paper  , we study the method for improving the efficiency of joint rsp ( jrsp ) subjected to noise with the help of weak measurement and its reversal measurement. taking a ghz based deterministic jrsp as an example,   we utilize the technique of weak measurement and its reversal to suppress the effect of the amplitude - damping noise firstly.   our study shows that the fidelity of the output state can be improved in the amplitude - damping noise.   we also study the effect of weak measurement and its reversal in other three types of noise usually encountered in real - world, namely, the bit - flip, phase - flip ( phase - damping ) and depolarizing noise.   our results show that the weak measurement has no effect for suppressing the bit - flip and phase - flip ( phase - damping ) noise, while has slight effect for suppressing the depolarizing noise.   our study is suitable for jrsp and rsp, and will be helpful for improving the efficiency of multiparticle entanglement based quantum secure communication in real implementation.
parton distributions of pseudoscalar @xmath0,@xmath1 and @xmath2 mesons obtained within the njl model using the pauli - villars regularization method are analyzed in terms of lo and nlo evolution, and the valence sea quark and gluon parton distributions for the pion are obtained at @xmath3 and compared to existing parametrizations at that scale.   surprisingly, the nlo order effects turn out to be small compared to the lo ones.   the valence distributions are in good agreement with experimental analyses, but the gluon and sea distributions come out to be softer in the high - x region and harder in the low - x region than the experimental analyses suggest.  .3 cm    _ pacs numbers : 13.60.hb, 12.39.ki, 12.39.fe + _    _ keywords : pseudoscalar mesons, parton distribution functions, _    _ structure functions, qcd evolution, nambu  jona - lasinio model _   -30pt    plus 2 mm minus 2 mm 23.0 cm -7.4 mm 2.6 mm    # 1#2^+#1_-#2@xmath4    * parton distributions functions of pion, kaon and eta pseudoscalar mesons in the njl model * +     r. m. davidson + department of physics, applied physics and astronomy, + rensselaer polytechnic institute, troy, new york, 12180 - 3590.   usa.   + e. ruiz arriola + departamento de fsica moderna + universidad de granada, e-18071 granada.   spain.
we derive a class of discrete nonlinear schrdinger ( dnls ) equations for general polynomial nonlinearity whose stationary solutions can be found from a reduced two - point algebraic problem.   it is demonstrated that the derived class of discretizations contains subclasses conserving classical norm or a modified norm and classical momentum.   these equations are interesting from the physical standpoint since they support stationary discrete solitons free of the peierls - nabarro potential. as a consequence, even in highly - discrete regimes,   solitons are not trapped by the lattice and they can be accelerated by even weak external fields. focusing on the cubic nonlinearity   we then consider a small perturbation around stationary soliton solutions and, solving corresponding eigenvalue problem, we ( i ) demonstrate that solitons are stable ; ( ii ) show that they have two additional zero - frequency modes responsible for their effective translational invariance ; ( iii ) derive semi - analytical solutions for discrete solitons moving at slow speed. to highlight the unusual properties of solitons in the new discrete models we compare them with that of the classical dnls equation giving several numerical examples.
as the opening review to the focus meeting `` stellar behemoths : red supergiants across the local universe '', i here provide a brief introduction to red supergiants, setting the stage for subsequent contributions.   i highlight some recent activity in the field, and identify areas of progress, areas where progress is needed, and how such progress might be achieved.
we present velocity - delay maps for optical,, and recombination lines in arp151, recovered by fitting a reverberation model to spectrophotometric monitoring data using the maximum - entropy method.   response is detected over the range 015  days, with the response confined within the virial envelope.   the balmer - line maps have similar morphologies but exhibit radial stratification, with progressively longer delays for h@xmath0 to h@xmath1 to h@xmath2.   the and response is confined within 12 days.   there is a deficit of prompt response in the balmer - line cores but strong prompt response in the red wings.   comparison with simple models identifies two classes that reproduce these features : freefalling gas, and a half - illuminated disk with a hotspot at small radius on the receding lune.   symmetrically illuminated models with gas orbiting in an inclined disk or an isotropic distribution of randomly inclined circular orbits can reproduce the virial structure but not the observed asymmetry.   radial outflows are also largely ruled out by the observed asymmetry.   a warped - disk geometry provides a physically plausible mechanism for the asymmetric illumination and hotspot features.   simple estimates show that a disk in the broad - line region of arp151 could be unstable to warping induced by radiation pressure.   our results demonstrate the potential power of detailed modeling combined with monitoring campaigns at higher cadence to characterize the gas kinematics and physical processes that give rise to the broad emission lines in active galactic nuclei.
recent results for the qcd phase structure at finite temperature and light - quark chemical potential are summarized, where the cases of @xmath0 and @xmath1 dynamical quark flavors are considered.   order parameters for the chiral and deconfinement transitions are obtained from solutions of a coupled set of truncated dyson - schwinger equations for the quark and gluon propagators of landau gauge qcd. based on very good agreement with lattice qcd for zero chemical potential the phase diagram in the whole t-@xmath2 plane and the appearance of a putative critical end - point at large chemical potential   are studied. _   keywords : _ critical end point, qcd phase diagram, dyson - schwinger equations
we report the detection of periodic ( @xmath0 hours ) bursts of extremely bright, 100% circularly polarized, coherent radio emission from the m9 dwarf tvlm 513 - 46546.   simultaneous photometric monitoring observations have established this periodicity to be the rotation period of the dwarf.   these bursts, which were not present in previous observations of this target, confirm that ultracool dwarfs can generate persistent levels of broadband, coherent radio emission, associated with the presence of kg magnetic fields in a large - scale, stable configuration.   compact sources located at the magnetic polar regions produce highly beamed emission generated by the electron cyclotron maser instability, the same mechanism known to generate planetary coherent radio emission in our solar system.   the narrow beams of radiation pass our line of sight as the dwarf rotates, producing the associated periodic bursts.   the resulting radio light curves are analogous to the periodic light curves associated with pulsar radio emission highlighting tvlm 513 - 46546 as the prototype of a new class of transient radio source.
we present a study of a very peculiar object found in the field of the cluster - lens abell 370.   this object displays, in _ hst _ imaging, a spectacular morphology comparable to nearby ring - galaxies. from spectroscopic observations at the cfht, we measured a redshift of @xmath0 based on the identification of  3727  and  3426  emission lines.   these emission lines are typical of starburst galaxies hosting a central active nucleus and are in good agreement with the assumption that this object is a ring galaxy.   this object is also detected with _   iso _ in the lw2 and lw3 filters, and the mid infra - red ( mir ) flux ratio favors a seyfert 1 type.   the shape of the ring is gravitationally distorted by the cluster - lens, and in particular by a nearby cluster elliptical galaxy.   using our cluster mass model, we can compute its intrinsic shape. requiring that the outer ring follows an ellipse we constrain the m / l ratio of the nearby galaxy and   derive a magnification factor of 2.5 @xmath1 0.2.   the absolute luminosities of the source are then @xmath2 and @xmath3 l@xmath4 l@xmath5 in the mid - ir.
the main astronomical source of r - process elements has not yet been identified.   one plausible site is neutron star mergers ( nsms ), but from perspective of the galactic chemical evolution, it has been pointed out that nsms can not reproduce the observed r - process abundance distribution of metal - poor stars at @xmath0 } < -3 $ ].   recently, tsujimoto & shigeyama ( 2014 ) pointed out that nsm ejecta can spread into much larger volume than ejecta from a supernova.   we re - examine the enrichment of r - process elements by nsms considering this difference in propagation using the chemical evolution model under the hierarchical galaxy formation. the observed r - process enhanced stars around @xmath0}\sim -3   $ ] are reproduced if the star formation efficiency is lower for low - mass galaxies under a realistic delay time distribution for nsms.   we show that a significant fraction of nsm ejecta escape from its host proto - galaxy to pollute intergalactic matter and other proto - galaxies.   the propagation of r - process elements over proto - galaxies changes the abundance distribution at @xmath0 } < -3 $ ] and obtains distribution compatible with observations of the milky way halo stars.   in particular, the pre - enrichment of intergalactic medium explains the observed scarcity of emp stars without ba and abundance distribution of r - process elements at @xmath0}\lesssim -3.5 $ ].
we study the photoreaction in the delta energy region using the qmd approach.   the proton and pion cross - sections are calculated and compared with experimental data. through this work   we examine the multistep contributions in the cross - sections and the @xmath0-@xmath1 dynamics.   = 10000
two - leg spin ladders have a rich phase diagram if rung, diagonal and plaquette couplings are allowed for. among the possible phases there are two haldane - type spin liquid phases without local order parameter, which differ, however, in the topology of the short range valence bonds. we show that these phases can be distinguished numerically by two different string order parameters.   we also point out that long range string- and dimer orders can coexist.
we study kinetic representations of flocking models.   they arise from agent - based models for self - organized dynamics, such as cucker - smale @xcite and motsch - tadmor @xcite models.   we prove flocking behavior for the kinetic descriptions of flocking systems, which indicates a concentration in velocity variable in infinite time.   we propose a discontinuous galerkin method to treat the asymptotic @xmath0-singularity, and construct high order positive preserving scheme to solve kinetic flocking systems.
we calculate the fermion self - energy at @xmath0 for the symanzik improved staggered fermion action used in recent lattice simulations by the milc collaboration.   we demonstrate that the algebraic approach to lattice perturbation theory, suggested by us recently @xcite, is a powerful tool also for improved lattice actions.
the xmm - newton spectral - fit database is an ongoing esa funded project aimed to construct a catalogue of spectral - fitting results for all the sources within the xmm - newton serendipitous source catalogue for which spectral data products have been pipeline - extracted ( @xmath0 120,000 x - ray source detections ).   the fundamental goal of this project is to provide the astronomical community with a tool to construct large and representative samples of x - ray sources by allowing source selection according to spectral properties.
in this note we introduce the ( homologically essential ) arc complex of a surface as a tool for studying properties of open book decompositions and contact structures. after characterizing destabilizability in terms of the essential translation distance of the monodromy of an open book   we given an application of this result to show that there are planer open books of the standard contact structure on @xmath0 with 5 ( or any number larger than 5 ) boundary components that do not destabilize.   we also show that any planar open book with 4 or fewer boundary components does destabilize.
we present, for the first time, the structure of the axisymmetric force  free magnetosphere of an aligned rotating magnetic dipole, in the case in which there exists a sufficiently large charge density ( whose origin we do not question ) to satisfy the ideal mhd condition, @xmath0, everywhere.   the unique distribution of electric current along the open magnetic field lines which is required for the solution to be continuous and smooth is obtained numerically. with the geometry of the field lines   thus determined we compute the dynamics of the associated mhd wind.   the main result is that the relativistic outflow contained in the magnetosphere is not accelerated to the extremely relativistic energies required for the flow to generate gamma rays.   we expect that our solution will be useful as the starting point for detailed studies of pulsar magnetospheres under more general conditions, namely when either the force - free and/or the ideal mhd condition @xmath0 are not valid in the entire magnetosphere. based on our solution  , we consider that the most likely positions of such an occurrence are the polar cap, the crossings of the zero space charge surface by open field lines, and the return current boundary, but _ not _ the light cylinder.   |    = 15pt
we study light - cone gauge string field theory in noncritical space - time dimensions.   such a theory corresponds to a string theory in a lorentz noninvariant background.   we identify the worldsheet theory for the longitudinal coordinate variables @xmath0 and study its properties.   it is a cft with the right value of virasoro central charge, using which we propose a brst invariant formulation of the worldsheet theory.        * light - cone gauge string field theory + in noncritical dimensions + *    yutaka baba@xmath1, nobuyuki ishibashi@xmath2, koichi murakami@xmath1    @xmath1_theoretical physics laboratory, riken, + wako, saitama 351 - 0198, japan _   @xmath2_institute of physics, university of tsukuba, + tsukuba, ibaraki 305 - 8571, japan _ +
as social networking takes to the mobile world, smartphone apps provide users with ever - changing ways to interact with each other. over the past couple of years, an increasing number of apps have entered the market offering end - to - end encryption, self - destructing messages, or some degree of anonymity  . however, little work thus far has examined the properties they offer.   to this end, this paper presents a taxonomy of 18 of these apps : we first look at the features they promise in their appeal to broaden their reach and focus on 8 of the more popular ones.   we present a technical evaluation, based on static and dynamic analysis, and identify a number of gaps between the claims and reality of their promises.
we introduce a toy model of the `` rat race '' in which individuals try to better themselves relative to the rest of the population.   an individual is characterized by a real - valued fitness and each advances at a constant rate by an amount that depends on its standing in the population.   the leader advances to remain ahead of its nearest neighbor, while all others advance by an amount that is set by the distance to the leader.   a rich dynamics occurs as a function of the mean jump size of the trailing particles. for small jumps,   the leader maintains its position, while for large jumps, there are long periods of stasis that are punctuated by episodes of explosive advancement and many lead changes.   intermediate to these two regimes, in a typical realization of the system, agents reach a common fitness and evolution grinds to a halt.
we demonstrate an experimental realization of remote state preparation via the quantum teleportation algorithm, using an entangled photon pair in the polarization degree of freedom as the quantum resource.   the input state is encoded on the path of one of the photons from the pair.   the improved experimental scheme allows us to control the preparation and teleportation of a state over the entire bloch sphere with a resolution of the degree of mixture given by the coherence length of the photon pair.   both the preparation of the input state and the implementation of the quantum gates are performed in a pair of chained displaced sagnac interferometers, which contribute to the overall robustness of the setup.   an average fidelity above 0.9 is obtained for the remote state preparation process.   this scheme allows for a prepared state to be transmitted on every repetition of the experiment, thus giving an intrinsic success probability of 1.
we present global 2d and 3d simulations of self - gravitating magnetized tori.   we used the 2d calculations to demonstrate that the properties of the mri are not affected by the presence of self - gravity : mhd turbulence and enhanced angular momentum transport follow the linear growth of the instability. in 3d, we have studied the interaction between an @xmath0 gravitational instability and mhd turbulence.   we found its strength to be significantly decreased by the presence of the latter, showing that both instabilities strongly interact in their non - linear phases.   we discuss the consequences of these results.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
in this paper we report the results of the first ever time - dependent general relativistic magnetohydrodynamic simulations of the magnetically dominated monopole magnetospheres of black holes.   it is found that the numerical solution evolves towards a stable steady - state solution which is very close to the corresponding force - free solution found by blandford and znajek.   contrary to the recent claims, the particle inertia does not become dynamically important near the event horizon and the force - free approximation provides a proper framework for magnetically dominated magnetospheres of black holes. for the first time,   our numerical simulations show the development of an ultra - relativistic particle wind from a rotating black hole. however, the flow remains poynting dominated all the way up to the fast critical point.   this suggests that the details of the so - called `` astrophysical load '', where the electromagnetic energy is transferred to particles, may have no effect on the efficiency of the blandford - znajek mechanism.       black hole physics  magnetic fields  methods : numerical.
i report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly - coupled quark - gluon plasma.   ( i ) i advertise that two of the several formalisms used to study this problem, the bdmps - zakharov formalism and the amy formalism ( the latter used only for infinite, uniform media ), can be made equivalent when appropriately formulated.   ( ii ) a standard technique to simplify calculations is to expand in inverse powers of logarithms @xmath0.   i give an example where such expansions are found to work well for @xmath1 where @xmath2 is the bremsstrahlung gluon energy.   ( iii ) finally, i report on perturbative calculations of @xmath3.
bulges in spiral galaxies have been supposed to be classified into two types : classical bulges or pseudobulges.   classical bulges are thought to form by galactic merger with bursty star formation, whereas pseudobulges are suggested to form by secular evolution.   @xcite suggested another bulge formation scenario, ` clump - origin bulge '.   he demonstrated using a numerical simulation that a galactic disc forms clumpy structures in the early stage of disc formation, then the clumps merge into a single bulge at the centre.   i perform a high - resolution @xmath0-body / sph simulation for the formation of the clump - origin bulge in an isolated galaxy model.   i find that the clump - origin bulge resembles pseudobulges in dynamical properties, but this bulge consists of old and metal - rich stars.   these natures, old metal - rich population but pseudobulge - like structures, mean that the clump - origin bulge can not be simply classified into classical bulges nor pseudobulges. from these results,   i discuss similarities of the clump - origin bulge to the milky way ( mw ) bulge.
we study ground state properties and excitation spectra for hard - core bosons on square and triangular lattices, at half filling, using series expansion methods.   nearest - neighbor repulsion between the bosons leads to the development of short - range density order at the antiferromagnetic wavevector, and simultaneously a roton minima in the density excitation spectra. on the square - lattice  , the model maps on to the well studied xxz model, and the roton gap collapses to zero precisely at the heisenberg symmetry point, leading to the well known spectra for the heisenberg antiferromagnet. on the triangular - lattice  , the collapse of the roton gap signals the onset of the supersolid phase.   our results suggest that the transition from the superfluid to the supersolid phase maybe weakly first order.   we also find several features in the density of states, including two - peaks and a sharp discontinuity, which maybe observable in experimental realization of such systems.
since february 1997 the bl lac object mkn 501 is in a `` high state '' of @xmath0-ray emission. the hegra collaboration has studied mkn 501 with their air erenkov telescopes on la palma. here   we report on observations with the 5 m@xmath1 telescope ( threshold @xmath2 1.5 tev ) operated in a stand alone mode.   we observed a rapidly varying flux between 0.5 to 6 times of that from the crab nebula. on average   a mkn 501 flux of @xmath3 has been determined.   the spectrum extends at least up to 10 tev with an integral power law coefficient of @xmath4 and seems to be steeper than in 1996.
we present the full next - to - leading order ( nlo ) corrected inclusive cross section for massive lepton pair production in longitudinally polarized proton - proton collisions.   all qcd partonic subprocesses have been included provided the lepton pair is created by a virtual photon, which is a valid approximation for @xmath0. like in unpolarized proton - proton scattering the dominant subprocess is given by the @xmath1-channel so that massive lepton pair production provides us with an excellent method to measure the spin density of the gluon.   using our calculations we give predictions for the longitudinal spin asymmetry measurements at the rhic.
the existence of a star with such a large mass means that the equation of state is stiff enough to provide a high enough pressure up to a fairly large central densities,.   such a stiff equation of state is possible if the ground state has nucleons as its constituents.   this further implies that a purely nucleon ground state may exist till about four times nuclear density which indicates that quarks in the nucleon are strongly bound and that the nucleon nucleon potential is strongly repulsive.   we find this to be so in a chiral soliton model for the nucleon which has bound state quarks.   we point out that this has important implications for the strong interaction @xmath0 vs t phase diagram.
one of the remarkable properties of the ii - vi diluted magnetic semiconductor ( znmn)se is the giant spin splitting of the valence band states under application of the magnetic field ( giant zeeman splitting ).   this splitting reveals strong exchange interaction between mn moments and semiconductor states. on the other hand,   no magnetic phase transition has been observed for systems with small mn content up to very low temperatures.   the latter property shows weakness of the exchange interaction between mn moments. in this paper, the local density approximation ( lda ) and the lda+u techniques are employed to study exchange interactions in ( znmn)se. supercell and frozen - magnon approaches applied earlier to iii - v diluted magnetic semiconductors are used.   it is found that both lda and lda+u describe successfully the combination of the strong zeeman splitting and weak interatomic exchange.   however, the physical pictures provided by two techniques differ strongly.   a detailed analysis shows that the lda+u method provides the description of the system which is much closer to the experimental data.
we analyze the equilibrium configuration for a modulated beam with sharp boundaries exposed to the fields self - generated by the interaction with a plasma. through a semi - analytical approach   we show the presence of multiple equilibrium configurations and we determine the one more suitable for wakefield excitation. once pointed out the absence of confinement for the front of the beam and the consequently divergence driven by the emittance, we study the evolution of the equilibrium configuration while propagating in the plasma, discarding all the others time - dependencies.   we show the onset of a rigid backward drift of the equilibrium configuration and we provide an explanation in the increasing length of the first bunch.
we calculate the transverse and time - time components of the instantaneous gluon propagator in coulomb gauge qcd by using an su(3 ) quenched lattice simulation on isotropic and anisotropic lattices.   we find that the gluon propagators suffer from strong discretization effects on the isotropic lattice ; on the other hand, those on the anisotropic lattices give a better scaling.   moreover, on these two type of lattices the transverse parts are significantly suppressed in the infrared region and have a turnover at about 500 . the high resolution to the temporal direction due to the anisotropy yields small discretization errors for the time - time gluon propagators, which also show an infrared enhancement as expected in the gribov - zwanziger confinement scenario.
we have observed the black hole candidate x - ray binary gx 339 - 4 at radio wavelengths before, during and after the 1998 high / soft x - ray state transition.   we find that the radio emission from the system is strongly correlated with the hard x - ray emission and is reduced by a factor @xmath0 during the high / soft state compared to the more usual low / hard state. at the points of state transition we note brief periods of unusually optically - thin radio emission which may correspond to discrete ejection events.   we propose that in the low / hard state black hole x - ray binaries produce a quasi - continuous outflow, in the high / soft state this outflow is suppressed, and that state transitions often result in one or more discrete ejection events.   future models for low / hard states, such as adaf / adios solutions, need to take into account strong outflow of relativistic electrons from the system.   we propose that the inferred comptonising corona and the base of the jet - like outflow are the same thing, based upon the strong correlation between radio and hard x - ray emission in gx 339 - 4 and other x - ray binaries, and the similarity in inferred location and composition of these two components.
the paper studies a method for solving elliptic partial differential equations posed on hypersurfaces in @xmath0, @xmath1.   the method allows a surface to be given implicitly as a zero level of a level set function.   a surface equation is extended to a narrow - band neighborhood of the surface.   the resulting extended equation is a non - degenerate pde and it is solved on a bulk mesh that is unaligned to the surface.   an unfitted finite element method is used to discretize extended equations.   error estimates are proved for finite element solutions in the bulk domain and restricted to the surface.   the analysis admits finite elements of a higher order and gives sufficient conditions for archiving the optimal convergence order in the energy norm.   several numerical examples illustrate the properties of the method.
we report the observation of tev @xmath0-rays from the cygnus region using the argo - ybj data collected from 2007 november to 2011 august.   several tev sources are located in this region including the two bright extended mgro j2019 + 37 and mgro j2031 + 41. according to the milagro data set, at 20 tev mgro   j2019 + 37 is the most significant source apart from the crab nebula.   no signal from mgro j2019 + 37 is detected by the argo - ybj experiment, and the derived flux upper limits at 90% confidence level for all the events above 600 gev with medium energy of 3 tev are lower than the milagro flux, implying that the source might be variable and hard to be identified as a pulsar wind nebula.   the only statistically significant ( 6.4 standard deviations ) @xmath0-ray signal is found from mgro j2031 + 41, with a flux consistent with the measurement by milagro.
we study neutrino induced one - pion production off the nucleon in and around the delta resonance region.   apart from the delta - pole mechanism we include background terms required by chiral symmetry.   these background terms give sizeable contributions in all channels. to better reproduce the anl @xmath0-differential cross section data  , we make a new fit of the @xmath1 axial nucleon to delta form factor.   the new result @xmath2 is some 30% smaller than the commonly accepted value.   this correction is compatible with most quark model estimates and a recent lattice calculation  @xcite.
observations with the hinode space observatory led to the discovery of predominantly horizontal magnetic fields in the photosphere of the quiet internetwork region. here   we investigate realistic numerical simulations of the surface layers of the sun with respect to horizontal magnetic fields and compute the corresponding polarimetric response in the  630  nm line pair.   we find a local maximum in the mean strength of the horizontal field component at a height of around 500  km in the photosphere, where it surpasses the vertical component by a factor of 2.0 or 5.6, depending on the initial and boundary conditions. from the synthesized stokes profiles we derive a mean horizontal field component that is,   respectively, 1.6 and 4.3 times stronger than the vertical component.   this is a consequence of both the intrinsically stronger flux density of, and the larger area occupied by the horizontal fields.   we find that convective overshooting expels horizontal fields to the upper photosphere, making the poynting flux positive in the photosphere, while this quantity is negative in the convectively unstable layer below it.
in 2001, phenix measured particle correlations of identical charged pions and kaons at mid - rapidity in au - au collisions at  = 200 gev.   bertsch - pratt radius parameters of pion pairs are studied for 9  regions from 0.2 to 2.0 gev / c and for 9 selections of collision centralities.   the pion radius parameters are consistent with the result at  = 130 gev, and the ratio  is below 1 in all  ranges up to 1.2 gev / c.   the radius parameters from charged kaon correlations are compared with those of pions.
this paper presents an efficient algorithm for robust network reconstruction of linear time - invariant ( lti ) systems in the presence of noise, estimation errors and unmodelled nonlinearities.   the method here builds on previous work @xcite on robust reconstruction to provide a practical implementation with polynomial computational complexity. following the same experimental protocol, the algorithm obtains a set of structurally - related candidate solutions spanning every level of sparsity.   we prove the existence of a magnitude bound on the noise, which if satisfied, guarantees that one of these structures is the correct solution.   a problem - specific model - selection procedure then selects a single solution from this set and provides a measure of confidence in that solution.   extensive simulations quantify the expected performance for different levels of noise and show that significantly more noise can be tolerated in comparison to the original method.
feynman s `` no - node '' theorem states that the conventional many - body ground - state wavefunctions of bosons in the coordinate representation is positive - definite.   this implies that time - reversal symmetry can not be spontaneously broken. in this article  , we review our progress in studying a class of new states of unconventional bose - einstein condensations beyond this paradigm.   these states can either be the long - lived metal - stable states of ultra - cold bosons in high orbital bands in optical lattices as a result of the `` orbital - hund s rule '' interaction, or the ground states of spinful bosons with spin - orbit coupling linearly dependent on momentum. in both cases,   feynman s argument does not apply.   the resultant many - body wavefunctions are complex - valued and thus break time - reversal symmetry spontaneously.   exotic phenomena in these states include the bose - einstein condensation at non - zero momentum, the ordering of orbital angular momentum moments, the half - quantum vortex, and the spin texture of skyrmions.
the electronic structure and the single - particle spectral density of a stripe array formed by ladder - like domain walls ( dws ) and by antiferromagnetic ( af ) domains of width 2 lattice spacings are computed and compared with arpes spectra from some doped cuprates belonging to the 214 family of compounds.   we assume that bond order is formed on legs in dws and that the phase of the sublattice magnetization changes by @xmath0 across each dw. the intensity map plotted in the coordination frame momentum - energy reproduces quite well the arpes spectra obtained at the doping level of @xmath1.   we consider this agreement as an argument for a scenario of coexisting bond - ordered regions and af regions in the stripe phase of moderately doped cuprates.
we determine the capacity - achieving input covariance matrices for coherent block - fading correlated mimo rician channels.   in contrast with the rayleigh and uncorrelated rician cases, no closed - form expressions for the eigenvectors of the optimum input covariance matrix are available.   both the eigenvectors and eigenvalues have to be evaluated by using numerical techniques.   as the corresponding optimization algorithms are not very attractive, we evaluate the limit of the average mutual information when the number of transmit and receive antennas converge to @xmath0 at the same rate.   we propose an attractive optimization algorithm of the large system approximant, and establish some convergence results.   numerical simulation results show that, even for a quite moderate number of transmit and receive antennas, the new approach provides the same results than direct maximization approaches of the average mutual information, while being much more computationally attractive.
the inclusive electromagnetic responses in the quasi  elastic region are calculated with a model which considers the terms of the cluster expansion containing a single correlation line.   the validity of this model is studied by comparing, in nuclear matter, its results with those of a complete calculation.   results in finite nuclei for both one and two  nucleon emission are presented.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )
text documents are complex high dimensional objects. to effectively visualize such data   it is important to reduce its dimensionality and visualize the low dimensional embedding as a 2-d or 3-d scatter plot. in this paper   we explore dimensionality reduction methods that draw upon domain knowledge in order to achieve a better low dimensional embedding and visualization of documents.   we consider the use of geometries specified manually by an expert, geometries derived automatically from corpus statistics, and geometries computed from linguistic resources.
we developed a method to calculate positions and widths of three - body resonances.   the method combines the hyperspherical adiabatic approach, slow variable discretization method ( tolstikhin _ et al.   _, j. phys.   b : at. mol.  . phys.   * 29 *, l389 ( 1996 ) ), and a complex absorbing potential.   the method can be used to obtain resonances having short - range or long - range wave functions. in particular, we have applied the method to obtain very shallow three - body efimov resonances for a model system ( nielsen _ et al.   _, phys.   rev.   a * 66 *, 012705 ( 2002 ) ).
we extend our previous first - principles theory for perovskite ferroelectric phase transitions to treat also antiferrodistortive phase transitions.   our approach involves construction of a model hamiltonian from a taylor expansion, first - principles calculations to determine expansion parameters, and monte carlo simulations to study the resulting system.   we apply this approach to three cubic perovskite compounds, srtio@xmath0, catio@xmath0, and nanbo@xmath0, that are known to undergo antiferrodistortive phase transitions.   we calculate their transition sequences and transition temperatures at the experimental lattice constants. for srtio@xmath0  , we find our results agree well with experiment. for more complicated compounds like catio@xmath0 and nanbo@xmath0, which can have many different structures with very similar energy,   the agreement is somewhat less satisfactory.
a new approach to phenomenological description of the charged particle multiplicity distributions in @xmath0 and @xmath1 collisions is presented.   the observed features of the data are interpreted on the basis of stochastic - physical ideas of multiple production. besides the processes of parton immigration and absorption, two and three patron   incremental and decremental recombinations are considered.   the complex behaviour of the multiplicity distributions at different energies is described by four parametric generalized hypergeometric distribution ( ghd ).   application of the proposed ghd to data measured by the cms, alice, and atlas collaborations suggests that soft multiparton recombination processes can manifest itself significantly in the structure of multiplicity distribution in @xmath2 interactions at very high energies.
the creation of single collective excitations in atomic ensembles via spontaneous raman emission plays a key role in several quantum communication protocols, starting with the seminal dlcz protocol [ l.- m.duan, m.d.   lukin, j.i.   cirac, and p. zoller, nature * 414 *, 413 ( 2001 ).   ] this process is usually analyzed theoretically under the assumptions that the write laser pulse inducing the raman transition is far off - resonance, and that the atomic ensemble is only homogeneously broadened.   here we study the impact of near - resonance excitation for inhomogeneously broadened ensembles on the collective character of the created atomic excitation.   our results are particularly relevant for experiments with hot atomic gases and for potential future solid - state implementations.
using fully relativistic geant4 simulation tool kit, the transport of energetic electrons generated in solar flares was monte - carlo simulated, and resultant bremsstrahlung gamma - ray spectra were calculated.   the solar atmosphere was approximated by 10 vertically - stacked zones.   the simulation took into account two important physical processes, that the bremsstrahlung photons emitted by precipitating relativistic electrons are strongly forward beamed toward the photosphere, and that the majority of these gamma - rays must be compton back - scattered by the solar atmosphere in order to reach the observer.   then, the compton degradation was found to make the observable gamma - ray spectra much softer than is predicted by simple analytic calculations.   the gamma - ray signals were found to be enhanced by several conditions, including a broad pitch - angle distribution of the electrons, a near - limb flare longitude, and a significant tilt in the magnetic field lines if the flare longitude is rather small.   these results successfully explain several important flare properties observed in the hard x - ray to gamma - ray range, including in particular those obtained with yohkoh. a comparison of the yohkoh spectrum from a goes x3.7 class limb flare on 1998   november 22, with a simulation assuming a broad electron pitch - angle distribution, suggests that gamma - rays from this particular solar flare were a mixture of direct bremsstrahlung photons and their comptonization.
we use the breakup absorption model to simultaneously describe the measured cross - sections of the complete fusion ( cf ), incomplete fusion ( icf ), and total fusion ( tf ) in nuclear reactions induced by weakly bound nuclei @xmath0li on @xmath1bi and @xmath2pt targets.   the absorption cross - sections are calculated using the continuum discretized coupled channels ( cdcc ) method with different choices of short range imaginary potentials to get the icf, cf and tf cross - sections.   it is observed that the cross - sections for deuteron - icf / deuteron - capture are of similar magnitude as the @xmath3-icf/@xmath3-capture, in case of @xmath4li projectile, while the cross - sections for triton - icf / triton - capture is more dominant than @xmath3-icf/@xmath3-capture in case of @xmath5li projectile.   both these observations are also corroborated by the experimental data.   the ratio of icf to tf cross - sections, which defines the value of fusion suppression factor is found to be in agreement with the data available from the literature.   the cross - section ratio of cf / tf and icf / tf show opposite behavior, the former decreases while the latter increases as the energy is lowered, which shows the dominance of icf at below barrier energies. we have also studied the correlation of the icf cross - sections with the non - capture breakup ( ncbu ) cross - sections as a function of energy, which shows that the ncbu is more significant than icf at below barrier energies.
in this paper we review penrose s weyl curvature conjecture which states that the concept of gravitational entropy and the weyl tensor is somehow linked, at least in a cosmological setting.   we give a description of a certain entity constructed from the weyl tensor, from the very early history of our universe until the present day.   inflation is an important mechanism in our early universe for homogenisation and isotropisation, and thus it must cause large effects upon the evolution of the gravitational entropy.   therefore the effects from inflationary fluids and a cosmological constant are studied in detail.
the generalized coherent state model, proposed previously for a unified description of magnetic and electric collective properties of nuclear systems, is used to study the ground state band charge density as well as the e0 transitions from @xmath0 to @xmath1.   the influence of the nuclear deformation and of angular momentum projection on the charge density is investigated.   the monopole transition amplitude has been calculated for ten nuclei.   the results are compared with some previous theoretical studies and with the available experimental data.   our results concerning angular momentum projection are consistent with those of previous microscopic calculations for the ground state density.   the calculations for the e0 transitions agree quite well with the experimental data.   issues like how the shape transitions or shape coexistence are reflected in the @xmath2 behavior are also addressed.
we present a homogeneous compilation of hi spectral parameters extracted from global 21 cm line spectra for some 9000 galaxies in the local universe ( heliocentric velocity @xmath0 km  s@xmath1 ) obtained with a variety of large single dish radio telescopes but reanalyzed using a single set of parameter extraction algorithms.   corrections to the observed hi line flux for source extent and pointing offsets and to the hi line widths for instrumental broadening and smoothing are applied according to model estimates to produce a homogenous catalog of derived properties with quantitative error estimates.   where the redshift is available from optical studies, we also provide flux measurements for an additional 156 galaxies classified as marginal hi detections and rms noise limits for 494 galaxies classified as nondetections. given the diverse nature of the observing programs contributing to it, the characteristics of the combined dataset are heterogeneous, and as such, the compilation is neither integrated hi line flux nor peak flux limited.   however, because of the large statistical base and homogenous reprocessing, the spectra and spectral parameters of galaxies in this optically targeted sample can be used to complement data obtained at other wavelengths to characterize the properties of galaxies in the local universe and to explore the large scale structures in which they reside.   6.5 truein
we analyze the spectral and transport properties of ballistic quasi one - dimensional systems in the presence of spin - orbit coupling and in - plane magnetic fields.   our results demonstrate that rashba precession and intersubband coupling must be treated on equal footing for wavevectors near the magnetic field induced gaps.   we find that intersubband coupling limits the occurrence of negative effective masses at the gap edges and modifies the linear conductance curves in the strong coupling limit.   the effect of the magnetic field on the spin textured orientation of the wire magnetization is discussed.
low surface brightness ( lsb ) galaxies are dominated by dark matter.   high - resolution rotation curves suggest that their total mass - density distributions are dominated by constant density cores rather than the steep and cuspy distributions found in cold dark matter ( cdm ) simulations.   the data are best described by a model with a soft core with an inner power - law mass - density slope @xmath0.   however no single universal halo profile provides an adequate description of the data.   the observed mass profiles appear to be inconsistent with @xmath1cdm.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
a linear dependence of the amplitude of broadband noise variability on flux for gbhc and agn has been recently shown by uttley & mchardy @xcite.   we present the long term evolution of this rms - flux - relation for cyg  x-1 as monitored from 19982002 with rxte.   we confirm the linear relationship in the hard state and analyze the evolution of the correlation for the period of 19962002. in the intermediate and the soft state, we find considerable deviations from the otherwise linear relationship. a possible explanation for the rms - flux - relation is a superposition of local mass accretion rate variations.
we present the first optical observations of a gamma ray burst ( grb ) afterglow using the 2-m robotic liverpool telescope ( lt ), which is owned and operated by liverpool john moores university and situated on la palma.   we briefly discuss the capabilities of lt and its suitability for rapid follow - up observations of early optical and infrared grb light curves. in particular, the combination of aperture, site, instrumentation and rapid response ( robotic over - ride mode aided by telescope s rapid slew and fully - opening enclosure ) makes the lt ideal for investigating the nature of short bursts, optically - dark bursts, and grb blast - wave physics in general.   we briefly describe the lt s key position in the robonet-1.0 network of robotic telescopes.   we present the lt observations of grb041006 and use its gamma - ray properties to predict the time of the break in optical light curve, a prediction consistent with the observations.   
it has generally been thought that in perturbed friedmann - lematre - robertson - walker models of the universe, global topology should not have any feedback effects on dynamics.   however, a weak - field limit heuristical argument, assuming a finite particle horizon for the transmission of gravitational signals, shows that a residual acceleration effect can occur.   the nature of this effect differs algebraically between different constant curvature 3-manifolds.   this potentially provides a selection mechanism for the 3-manifold of comoving space.
the discovery of main belt comets ( mbcs ) has raised many questions regarding the origin and activation mechanism of these objects.   results of a study of the dynamics of these bodies suggest that mbcs were formed in - situ as the remnants of the break - up of large icy asteroids.   simulations show that similar to the asteroids in the main belt, mbcs with orbital eccentricities smaller than 0.2 and inclinations lower than @xmath0 have stable orbits implying that many mbcs with initially larger eccentricities and inclinations might have been scattered to other regions of the asteroid belt. among scattered mbcs,   approximately 20% reach the region of terrestrial planets where they might have contributed to the accumulation of water on earth. simulations also show that collisions among mbcs and small objects could have played an important role in triggering the cometary activity of these bodies.   such collisions might have exposed sub - surface water ice which sublimated and created thin atmospheres and tails around mbcs.   this paper discusses the results of numerical studies of the dynamics of mbcs and their implications for the origin of these objects.   the results of a large numerical modeling of the collisions of m - sized bodies with km - sized asteroids in the outer part of the asteroid belt are also presented and the viability of the collision - triggering activation scenario is discussed.
psr j0205 + 6449 is a x - ray and radio pulsar in supernova remnant 3c 58.   we report on observations of the central region of 3c 58 using the 4.2-m william herschel telescope with the intention of identifying the optical counterpart of psr j0205 + 6449 and characterising its pulsar wind nebula. around the pulsar position   we identified extended emission with a magnitude of @xmath0, @xmath1 and @xmath2 consistent with a pulsar wind nebula. from the r - band image we identified three knots with @xmath3 = @xmath4 ( o1 ), @xmath5 ( o2 ) and @xmath6 ( o3 ).   we confirm the presence of an optical pulsar wind nebula around psr j0205 + 6449 and give an upper limit of @xmath7 24 for the optical magnitude of the pulsar.   furthermore we make the tentative suggestion that our object o1, with an @xmath7 24.08 is the optical counterpart.   if confirmed the pulsar would have an @xmath8 and an optical efficiency of about 5% of the crab pulsar.   such a low efficiency is more consistent with the characteristic age of the pulsar rather than that of sn 1181.       pulsars : individual : psr j0205 + 6449
we present a re - analysis of the cosmic confusion hypothesis, elucidating the degree to which `` confusion '' can be expected to hold in a class of flat, adiabatic models.   this allows us to devise a simple and accurate fitting function for the height of the first peak in the radiation power spectrum in a wide range of inflationary inspired models.   the range preferred by current data is given, together with a discussion of the impact of measurements of the peak height on constraining models of structure formation.   -.2 in -.6 in 8.5 in    epsf    # 1to 0pt#1
recent low - temperature scanning tunnelling spectroscopy experiments on the surface of bi@xmath0sr@xmath0cacu@xmath0o@xmath1 have revealed a strong positive correlation between the position of localized resonances at -960 mev identified with interstitial oxygen dopants and the size of the local spectral gap.   we review efforts to understand these correlations within a model where the dopants modulate the pair interaction on an atomic scale.   we provide further evidence for this model by comparing the correlations between the dopants and the local density of states with experimental results.   pair mechanism, d - wave superconductivity, disorder, stm, theory.
we discuss the inclusive production of @xmath0 mesons in deep - inelastic scattering ( dis ) via the electromagnetic, weak neutral, and charged currents within the factorization formalism of nonrelativistic quantum chromodynamics.   theoretical predictions are confronted with experimental data of @xmath1 and @xmath2 dis taken by the h1 collaboration at desy hera and the chorus collaboration at cern, respectively.
to circumvent the spatial effects of resolution on galaxy classification, the images of 233 objects of known redshift in the hubble deep field ( hdf ) and its flanking fields ( ff ) that have redshifts in the range @xmath0 were degraded to the resolution that they would have had if they were all located at a redshift @xmath1. as in paper xiv of the present series, the effects of shifts in rest wavelength were mitigated by using @xmath2-band images for the classification of galaxies with @xmath3 and @xmath4-band images for objects with redshifts @xmath5.   a special effort was made to search for bars in distant galaxies.   the present data strongly confirm the previous conclusion that the hubble tuning fork diagram only provides a satisfactory framework for the classification of galaxies with @xmath6.   more distant disk galaxies are often difficult to shoehorn into the hubble classification scheme.   the paucity of barred spirals and of grand - design spirals at large redshifts is confirmed.   it is concluded that the morphology of disk galaxies observed at look - back times smaller than 34 gyr differs systematically from that of more distant galaxies viewed at look - back times of 48 gyr.   the disks of late - type spirals at @xmath7 are seen to be more chaotic than those of their nearer counterparts.   furthermore the spiral structure in distant early - type spirals appears to be less well - developed than it is in nearby early - galaxies.
we compute the dimensionless relativistic periastron advance parameter @xmath0, which is measurable from the timing of relativistic binary pulsars.   we employ for the computation the recently derived keplerian - type parametric solution to the post - newtonian ( pn ) accurate conservative dynamics of spinning compact binaries moving in eccentric orbits. the parametric solution and hence the parameter @xmath0 are applicable for the cases of _ simple precession _, namely, case ( i ), the binary consists of equal mass compact objects, having two arbitrary spins, and case ( ii ), the binary consists of compact objects of arbitrary mass, where only one of them is spinning with an arbitrary spin.   our expression, for the cases considered, is in agreement with a more general formula for the 2pn accurate @xmath0, relevant for the relativistic double pulsar psr j07373039, derived by damour and schfer many years ago, using a different procedure.
this paper explores the potential of a newly developed conjugate filter oscillation reduction ( cfor ) scheme for shock - capturing under the influence of natural high - frequency oscillations.   the conjugate low - pass and high - pass filters are constructed based on the principle of the discrete singular convolution.   two euler systems, the advection of an isentropy vortex flow and the interaction of shock - entropy wave are considered to demonstrate the utility of the cfor scheme. computational accuracy and order of approximation   are examined and compared with the literature.   some of the best numerical results are obtained for the shock - entropy wave interaction.   numerical experiments indicate that the proposed scheme is stable, conservative and reliable for the numerical simulation of hyperbolic conservation laws.   u
we plan to take advantage of the unprecedented combination of low thermal background and high resolution provided by the 6.5 m mmt s adaptive secondary mirror, to target the 3 - 5 micron atmospheric window where giant planets are expected to be anomalously bright.   we are in the process of building a 3 - 5 micron coronograph that is predicted to be sensitive to planets as close as 0.4 arcsec to the parent star.   we expect to be able to detect giant planets down to 5 times jupiter s mass for a 1 gyr old system at 10 pc.   we plan to carry out a survey which is complementary to the radial velocity detections of planets and constructed to characterize the prevalence and distribution of giant planets around nearby, sun - like stars.   address = steward observatory, 933 n. cherry ave, tucson, az 85721 + freed@as.arizona.edu     address = steward observatory, 933 n. cherry ave, tucson, az 85721 + freed@as.arizona.edu     address = steward observatory, 933 n. cherry ave, tucson, az 85721 + freed@as.arizona.edu
investigating the beam  beam limit in the lhc is of great importance, since identifying its source is crucial for the luminosity optimization scenario.   several experiments were carried out to search for this limit and check whether it is dominated by the head - on ( ho ) or the long - range ( lr ) interactions. in this paper only the ho collision effects will be considered, tracking the evolution of the maximum tune shift achieved during the dedicated machine developments and the special high pile - up fills.
in this review, we summarize the theoretical development on the electric dipole moment of light nuclei. we first describe the nucleon level cp violation and its parametrization.   we then present the results of calculations of the edm of light nuclei in the ab initio approach and in the cluster model.   the analysis of the effect of several models beyond standard model is presented, together with the prospects for its discovery.   the advantage of the electric dipole moment of light nuclei is focused in the point of view of the many - body physics.   the evaluations of the nuclear electric dipole moment generated by the @xmath0-term and by the cp phase of the cabibbo - kobayashi - maskawa matrix are also reviewed.   # 1
we investigate how controlling induced eddy currents in thin film ferromagnet - normal metal ( fm / nm ) structures can be used to tailor the local microwave ( mw ) fields in ferromagnetic resonance ( fmr ) experiments.   the mw fields produced by eddy currents will in general have a relative phase shift with respect to the applied mw field which depends on the sample geometry.   the induced fields can thus partially compensate the applied mw field, effectively screening the fm in selected parts of the sample.   the highly localized fields produced by eddy currents enable the excitation of spin wave modes with non - zero wave vectors ( @xmath0 ), in contrast to the uniform @xmath1 mode normally excited in fmr experiments.   we find that the orientation of the applied mw field is one of the key parameters controlling the eddy - current effects.   the induced currents are maximized when the applied mw field is oriented perpendicular to the sample plane.   increasing the magnitude of the eddy currents results in a stronger induced mw field, enabling a more effective screening of the applied mw field as well as an enhanced excitation of spin wave modes.   this investigation underlines that eddy currents can be used to control the magnitude and phase of the local mw fields in thin film structures.
this report describes in detail the generation of a `` truth '' spectrum of hr  6348, using observations with the short - low ( sl ) module of the infrared spectrograph of hr  6348, and the a dwarfs @xmath0  lac and @xmath1  umi. using spectral ratios  , we can propagate kurucz models of the a dwarfs to the k giant hr  6348, which can then serve to calibrate the remaining database of sl spectra.   mitigation in the vicinity of the pfund-@xmath0 line is necessary to reduce residual artifacts at 7.45 . in general  , the new sl spectrum of hr  6348 has a spectroscopic fidelity of @xmath20.5  % or better.   artifacts from the hydrogen recombination lines in the a dwarfs will generally be smaller than this limit, although the residual artifact from the blend of lines near pfund-@xmath0 exceeds the limit at @xmath20.7  %.
the light - quark correlator in the axial - vector channel is used, in conjunction with finite energy qcd sum rules at finite temperature, in order to ( a ) establish a relation between chiral - symmetry restoration and deconfinement, and ( b ) determine the temperature behavior of the @xmath0 width and coupling.   results indicate that deconfinement takes place at a slightly lower temperature than chiral - symmetry restoration, although this difference is not significant given the accuracy of the method.   the behaviour of the @xmath0 parameters is consistent with quark - gluon deconfinement, as the width grows and the coupling decreases with increasing temperature.
sufficient dimension reduction reduces the dimensionality of data while preserving relevant regression information. in this article  , we develop minimum average deviance estimation ( made ) methodology for sufficient dimension reduction.   it extends the minimum average variance estimation ( mave ) approach of xia et al.   ( 2002 ) from continuous responses to exponential family distributions to include binomial and poisson responses.   local likelihood regression is used to learn the form of the regression function from the data.   the main parameter of interest is a dimension reduction subspace which projects the covariates to a lower dimension while preserving their relationship with the outcome. to estimate this parameter within its natural space  , we consider an iterative algorithm where one step utilizes a stiefel manifold optimizer.   we empirically evaluate the performance of three prediction methods, two that are intrinsic to local likelihood estimation and one that is based on the nadaraya - watson estimator.   initial results show that, as expected, made can outperform mave when there is a departure from the assumption of additive errors.
we study the thermal evolution of neutron stars in the presence of hyperons or kaons in the core.   our results indicate that the nucleon and hyperon direct urca processes play crucial roles for the cooling of neutron stars.   the presence of hyperons drives fast cooling mechanisms in two ways : 1 ) it allows the hyperon direct urca prior to the nucleon direct urca, 2 ) and it makes the nucleon direct urca more feasible by reducing the neutron fermi momentum.   we found that the neutron star equation of state ( eos ) with hyperons can be consistent with both mass and temperature observations.   we also found that the neutron star eos with kaon condensation can be consistent with observations, even though the cooling behavior is seldom useful to identify or isolate the effect of kaon condensation.   neutron star, neutron star cooling, kaon, hyperons in dense matter    # 1
we present a quasar candidate identification technique based on multicolor photometry.   the traditional multi - dimensional method ( 2 @xmath0 n dimensions, where n is the number of the color - color diagrams ) is reduced to a one - dimensional technique, which consists in a standard fitting procedure, where the observed spectral energy distributions are compared to quasar simulated spectra and stellar templates.   this new multicolor approach is firstly applied to simulated catalogues and its _ efficiency _ is examined in various redshift ranges, as a function of the filter combination and the available observing time for spectroscopy.   we conclude that this method is better suited than the usual multicolor selection techniques to quasar identification, especially for high - redshift quasars.   the application of the method to real quasar samples found in the literature results in an _ efficiency _   comparable to the one obtained from the use of color - color diagrams.   the major advantage of the new method is the estimation of the _ photometric _ redshift of quasar candidates, enabling, in almost all cases, spectroscopy to be targeted to best suited wavelength ranges.
we show that the noncommutativity of space  time destroys the renormalizability of the @xmath0 expansion of the @xmath1 gross  neveu model.   a similar statement holds for the noncommutative nonlinear sigma model.   however, we show that, up to the subleading order in @xmath0 expansion, the noncommutative supersymmetric @xmath1 nonlinear sigma model becomes renormalizable in @xmath2.   we also show that dynamical mass generation is restored and there is no catastrophic uv / ir mixing. unlike the commutative case  , we find that the lagrange multiplier fields, which enforce the supersymmetric constraints, are also renormalized. for @xmath3 the divergence of the four point function of the basic scalar field, which in @xmath2 is absent, can not be eliminated by means of a counterterm having the structure of a moyal product.
we report on a study of qcd thermodynamics with three flavors of quarks, using a symanzik improved gauge action and the asqtad @xmath0 improved staggered quark action.   simulations were carried out with lattice spacings @xmath1, @xmath2 and @xmath3 both for three degenerate quarks with masses less than or equal to the strange quark mass, @xmath4, and for degenerate up and down quarks with masses in the range @xmath5, and the strange quark mass fixed near its physical value.   we present results for standard thermodynamics quantities, such as the polyakov loop, the chiral order parameter and its susceptibility. for the quark masses studied to date   we find a rapid crossover rather than a _ bona fide _ phase transition.   we have carried out the first calculations of quark number susceptibilities with three flavors of sea quarks.   these quantities are of physical interest because they are related to event - by - event fluctuations in heavy ion collision experiments.   comparison of susceptibilities at different lattice spacings show that our results are close to the continuum values.
we report the discovery of two new low - mass, thermally bloated, hot white dwarfs among the _ kepler _ sample of eclipsing binaries.   these are kic 9164561 and kic 10727668 with orbital periods of 1.2670 and 2.3058 days, respectively.   the current primary in both systems is an a star of about 2 @xmath0.   this brings the number of similar binaries among the _ kepler _ sample to six, and the two new systems have the shortest orbital periods among them.   the white dwarf in kic 9164561 has the largest thermal bloating, compared to its cold degenerate radius, of about a factor of 14.   we utilize rv measurements of the a star in kic 9164561 to determine the white dwarf mass rather accurately : @xmath1.   the mass of the white dwarf in kic 10727668 is based on the doppler boosting signal in the _ kepler _ photometry, and is less accurately determined to be @xmath2.   based on the inferred radii and effective temperatures of these two white dwarfs we are able to make an _ independent _ theoretical estimate of their masses to within @xmath30.01 @xmath0 based on evolutionary models of their cooling history after they lose their hydrogen - rich envelopes.   we also present evidence that there is a third body in the kic 9164561 system with an orbital period of @xmath4 years.
a stroboscope designed to observe pulsars in the optical spectrum is presented.   the absolute phase of the stroboscope is synchronized to better than @xmath0s with the known radio ephemerides for a given pulsar.   the absolute timing is provided by the gps clock.   with such a device phase resolved photometry of pulsars can be performed.   we demonstrate the instrument s capabilities with the results of a set of observations of the crab pulsar, the brightest of the known optical pulsars, with a visual magnitude of @xmath1, and a rotational frequency of @xmath2hz.
the parameter fit from a model grid is limited by our capability to reduce the number of models, taking into account the number of parameters and the non linear variation of the models with the parameters.   the local multilinear regression ( lmlr ) algorithms allow one to fit linearly the data in a local environment.   the matisse algorithm, developed in the context of the estimation of stellar parameters from the gaia rvs spectra, is connected to this class of estimators.   a two - steps procedure was introduced.   a raw parameter estimation is first done in order to localize the parameter environment.   the parameters are then estimated by projection on specific vectors computed for an optimal estimation.   the matisse method is compared to the estimation using the objective analysis. in this framework  , the kernel choice plays an important role.   the environment needed for the parameter estimation can result from it.   the determination of a first parameter set can be also avoided for this analysis.   these procedures based on a local projection can be fruitfully applied to non linear parameter estimation if the number of data sets to be fitted is greater than the number of models.   address = observatoire de la cte dazur bp4229 + 06304 nice cedex 4, france     address = observatoire de la cte dazur bp4229 + 06304 nice cedex 4, france     address = observatoire de la cte dazur bp4229 + 06304 nice cedex 4, france
group theoretic method for the systematic study of multi - quark states is developed.   the calculation of matrix elements of many - body hamiltonian is simplified by transforming the physical bases ( quark cluster bases ) to symmetry bases ( group chain classified bases ), where the fractional parentage expansion method can be used.   five - quark system is taken as an example in this study.   the jaffe - wilczek @xmath0 configuration is chosen as one of examples to construct the physical bases and the transformation coefficients between physical bases and symmetry ones are shown to be related to the @xmath1 isoscalar factors and a complete transformation coefficients table is given.   the needed isoscalar factors and fractional parentage coefficients had been calculated with our new group representation theory and published before.   three quark models : the naive glashow - isgur, salamanca and quark delocalization color screening, are used to show the general applicability of the new multi - quark calculation method and general results of constituent quark models for five - quark states are given.
we use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long gamma - ray bursts observed with _ bepposax _ and selected on the basis of their good optical and nir coverage, from simultaneous fits to nir, optical and x - ray afterglow data, in count space and including the effects of metallicity. in no cases   is a mw - like extinction preferred, when testing mw, lmc and smc extinction laws.   the 2175  bump would in principle be detectable in all these afterglows, but is not present in the data.   an smc - like gas - to - dust ratio or lower value can be ruled out for 4 of the hosts analysed here ( assuming smc metallicity and extinction law ) whilst the remainder of the sample have too large an error to discriminate.   we provide a more accurate estimate of the line - of - sight extinction and improve upon the uncertainties for the majority of the extinction measurements made in previous studies of this sample.   we discuss this method to determine extinction values in comparison with the most commonly employed existing methods.
the activities towards the fabrication and test of a 1m@xmath0 semi - digital hadronic calorimeter are reviewed.   the prototype sampling planes would consist of 1m@xmath1 micromegas chambers with 1cm@xmath1 granularity and embedded 2 bits readout suitable for pfa calorimetry at an ilc detector.   + the design of the 1m@xmath1 chamber is presented first, followed by an overview of the basic performance of small prototypes.   the basic units composing the 1m@xmath1 chamber are 32@xmath348cm@xmath1 boards with integrated electronics and a micro - mesh. results of characterization tests of such boards are shown.   micromegas as a proportional detector is well suited for semi - digital hadronic calorimetry. in order to quantify the gain in performance when using one or more thresholds, simulation studies are being carried out,   some of which will be reported in this contribution.
the fundamental plane ( fp ) describes the relation between the stellar mass, size, and velocity dispersion of elliptical galaxies ; the faber   jackson relation ( fjr ) is its projection onto \{mass, velocity } space. in this work   we redeploy and expand the framework of  @xcite to ask whether abundance matching - based @xmath0cdm models that have shown success in matching the spatial distribution of galaxies are also capable of explaining key properties of the fjr and fp, including their scatter. within our framework,   agreement with the normalisation of the fjr requires haloes to expand in response to disc formation.   we find that the tilt of the fp may be explained by a combination of the observed non - homology in galaxy structure and the variation in mass - to - light ratio produced by abundance matching with a universal initial mass function ( imf ), provided that the anisotropy of stellar motions is taken into account.   however, the predicted scatter around the fp is considerably increased by situating galaxies in cosmologically - motivated haloes due to variations in halo properties at fixed stellar mass, and appears to exceed that of the data.   this implies that additional correlations between galaxy and halo variables may be required to fully reconcile these models with elliptical galaxy scaling relations.   = 1        galaxies : formation - galaxies : fundamental parameters - galaxies : haloes - galaxies : kinematics and dynamics - galaxies : elliptical - dark matter.
muon ionization cooling provides the only practical solution for preparing high brightness beams necessary for a neutrino factory or muon collider.   the muon ionization cooling experiment ( mice ) is under development at the rutherford appleton laboratory ( uk ).   it comprises a dedicated beam line designed to generate a range of input emittances and momenta with time - of - flight and cherenkov detectors to select a pure muon beam. a first measurement of emittance is performed in the upstream magnetic spectrometer with a scintillating fiber tracker.   a cooling cell will then follow, alternating energy loss in liquid hydrogen and acceleration by rf cavities. a second spectrometer identical to the first and another particle identification system provide a measurement of the outgoing emittance. in late 2009  , it is expected that the beam and many of the particle identification detectors will be in the final commissioning phase, and the first measurement of input beam emittance will take place in 2010.   the steps of commissioning, emittance measurement and cooling will be described.
the scaling behavior of anderson impurity models each of which with a different site energy @xmath0 is examined close to the mott - anderson transition.   depending on its impurity energy @xmath0, in the critical regime a site turns into a local magnetic moment, as indicated by a vanishing quasiparticle weight @xmath1, or remains nearly doubly occupied or nearly empty, corresponding to @xmath2. in this paper, we present the scaling behavior of @xmath3 as a function of the on - site energy @xmath0 and the distance @xmath4 to the transition, and interpret our result in terms of an appropriate beta function @xmath5.
we consider the resonant production of charged sleptons at the lhc via r - parity violation (  ) followed by gauge decays to a charged lepton and a neutralino which then decays via.   this gives a signature of two like - sign charged leptons. in the simulation   we include the full hadronisation via monte carlo programs.   we find a background, after cuts, of @xmath0 events for an integrated luminosity of @xmath1.   a preliminary study of the signal suggests that couplings of @xmath2 for a smuon mass of @xmath3   and smuon masses of up to @xmath4   for couplings of @xmath5 can be probed.   + 0.6 cm + _ @xmath6 department of physics, theoretical physics, university of oxford, _ + _ 1 keble road, oxford ox1 3np, u.k.   _ + 0.2 cm
nuclear data uncertainties in the production of @xmath0 nuclei in massive stars have been quantified in a monte carlo procedure.   bespoke temperature - dependent uncertainties were assigned to different types of reactions involving nuclei from fe to bi.   their simultaneous impact was studied in postprocessing explosive trajectories for three different stellar models.   it was found that the grid of mass zones in the model of a 25 @xmath1 star, which is widely used for investigations of @xmath0 nucleosynthesis, is too crude to properly resolve the detailed temperature changes required for describing the production of @xmath0 nuclei. using models with finer grids for 15 @xmath1 and 25 @xmath1 stars with initial solar metallicity  , it was found that most of the production uncertainties introduced by nuclear reaction uncertainties are smaller than a factor of two. since a large number of rates   were varied at the same time in the monte carlo procedure, possible cancellation effects of several uncertainties could be taken into account.   key rates were identified for each @xmath0 nucleus, which provide the dominant contribution to the production uncertainty.   these key rates were found by examining correlations between rate variations and resulting abundance changes.   this method is superior to studying flow patterns, especially when the flows are complex, and to individual, sequential variation of a few rates.       nuclear reactions, nucleosynthesis, abundances  stars : abundances  supernovae : general
analyses of stellar spectra often begin with the determination of a number of parameters that define a model atmosphere.   this work presents a prototype for an automated spectral classification system that uses a 150  - wide region around h@xmath0, and applies to stars of spectral types a to k with normal ( scaled solar ) chemical composition.   the new tool exploits synthetic spectra based on plane - parallel flux - constant model atmospheres.   the input data are high signal - to - noise spectra with a resolution greater than about 1 . the output parameters are forced to agree with an external scale of effective temperatures, based on the infrared flux method.   the system is fast  a spectrum is classified in a few seconds and well - suited for implementation on a web server.   we estimate upper limits to the @xmath1 random error in the retrieved effective temperatures, surface gravities, and metallicities as 100 k, 0.3 dex, and 0.1 dex, respectively.       methods : data analysis  techniques : spectroscopic  stars : fundamental parameters.
we examine the quantum states produced through parametric amplification with internal quantum noise.   the internal diffusion arises by coupling both modes of light to a reservoir for the duration of the interaction time.   the wigner function for the diffused two - mode squeezed state is calculated.   the nonlocality, separability, and purity of these quantum states of light are discussed.   in addition, we conclude by studying the nonlocality of two other continuous variable states : the werner state and the phase - diffused state for two light modes. +
starting from the qcd action in an instanton - like su(2 ) yang - mills field theory, we derive equations of motion in minkowski space.   possible bubble collisions are studied in a @xmath0-dimension reduction.   we find gluonic structures which might give rise to cmbr effects.   pacs indices:12.38.lg,12.38.mh,98.80.cq,98.80hw    keywords : cosmology ; qcd phase transition ; bubble collisions    # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )
peeling, shearing, and sliding are important mechanical phenomena in van der waals solids.   however, theoretically they have been studied mostly using minimal periodic cells and in the context of accurate quantum simulations. here  , we investigate the peeling of large - scale multilayer graphene stacks with varying thicknesses, stackings, and peeling directions by using classical molecular dynamics simulations with a registry - dependent interlayer potential.   simulations show that, while at large scale the peeling proceeds smoothly, at small scale the registry shifts and sliding patterns of the layers are unexpectedly intricate and depend both on the initial stacking and on the peeling direction.   these observations indicate that peeling and concomitant kink formations may well transform stacking order and thereby profoundly influence the electronic structures of such multilayer solids.
three experimental concepts investigating possible anisotropy of the speed of light are presented.   they are based on i ) beam deflection in a 180@xmath0 magnetic arc, ii ) narrow resonance production in an electron - positron collider, and iii ) the ratio of magnetic moments of an electron and a positron moving in opposite directions.   there are several well known experiments which investigate the one - way speed of light @xmath1 ; see the review and analysis in refs.   @xcite. here   we present related experimental schemes based on a high energy electron ( positron ) beam.   the experiments test isotropy of the maximum speed, but we refer to the speed of light assuming the photon to be massless.   a recent experiment at the storage ring esrf ( grenoble ) established a stringent constraint on the speed of light anisotropy of @xmath2 using the compton back - scattering method  @xcite.    in this letter   we discuss three other methods which could be used in a search for directional variation of the speed of light and/or related effects.   their common feature is a large value of the lorentz factor of the electron ( positron ) beam, @xmath3, of a few @xmath4.   they are based on various techniques for the beam momentum measurement.
we report the discovery of 182 new southern stars with proper motion larger than @xmath0 yr@xmath1.   the stars were found in an expansion of the superblink proper motion survey to 8980 square degrees south of decl.=-30@xmath2.   the new high proper motion stars include 123 objects with @xmath3 yr@xmath1, and 5 with @xmath4.   these new stars consist in a variety of nearby red dwarfs and white dwarfs, and ( slightly more distant ) red halo subdwarf, and are all prime targets for follow - up spectroscopic and astrometric ( parallax ) observations.   comparison with previous proper motion surveys in the southern sky suggests that superblink has a recovery rate between @xmath5 and @xmath6 at southern declinations for stars with red magnitude @xmath7 and proper motion in the range @xmath8 yr@xmath1.   this survey makes a significant addition to the census of high proper motion stars at southern declinations.
feature selection in learning to rank has recently emerged as a crucial issue. whereas   several preprocessing approaches have been proposed, only a few works have been focused on integrating the feature selection into the learning process. in this work,   we propose a general framework for feature selection in learning to rank using svm with a sparse regularization term.   we investigate both classical convex regularizations such as @xmath0 or weighted @xmath0 and non - convex regularization terms such as log penalty, minimax concave penalty ( mcp ) or @xmath1 pseudo norm with @xmath2.   two algorithms are proposed, first an accelerated proximal approach for solving the convex problems, second a reweighted @xmath0 scheme to address the non - convex regularizations.   we conduct intensive experiments on nine datasets from letor 3.0 and letor 4.0 corpora.   numerical results show that the use of non - convex regularizations we propose leads to more sparsity in the resulting models while prediction performance is preserved.   the number of features is decreased by up to a factor of six compared to the @xmath0 regularization.   in addition, the software is publicly available on the web.   feature selection, learning to rank, regularized svm, sparsity, fbs algorithms, non - convex regularizations.
we analyze the @xmath0 model at low doping @xmath1 by chiral perturbation theory and show that the ( 1,0 ) spiral state is stabilized by the presence of @xmath2 above critical values around @xmath3, assuming @xmath4.   we find that the ( magnon mediated ) hole - hole interactions have an important effect on the region of charge stability in the space of parameters @xmath2, generally increasing stability, while the stability in the magnetic sector is guaranteed by the presence of spin quantum fluctuations ( order from disorder effect ).   these conclusions are based on perturbative analysis performed up to two loops, with very good convergence.
in this paper, we investigate the robust transceiver design for dual - hop amplify - and - forward ( af ) mimo relay systems with gaussian distributed channel estimation errors.   aiming at maximizing the mutual information under imperfect channel state information ( csi ), source precoder at source and forwarding matrix at the relay are jointly optimized.   using some elegant attributes of matrix - monotone functions, the structures of the optimal solutions are derived first. then based on the derived structure   an iterative waterfilling solution is proposed.   several existing algorithms are shown to be special cases of the proposed solution.   finally, the effectiveness of the proposed robust design is demonstrated by simulation results.
for the first time we have investigated the behavior of fully micro - fabricated low temperature metallic magnetic calorimeters ( mmcs ) after undergoing an ion - implantation process.   this experiment had the aim to show the possibility to perform a high precision calorimetric measurement of the energy spectrum following the electron capture of @xmath0ho using mmcs having the radioactive @xmath0ho ions implanted in the absorber.   the implantation of @xmath0ho ions was performed at isolde - cern.   the performance of a detector that underwent an ion - implantation process is compared to the one of a detector without implanted ions.   the results show that the implantation dose of ions used in this experiment does not compromise the properties of the detector.   in addition an optimized detector design for future @xmath0ho experiments is presented.   neutrino mass, @xmath0ho, electron capture, low temperature detectors, ion - implantation
we examine the stability of the  coast " motion of fish, that is to say, the motion of a neutrally buoyant fish at constant speed in a straight line.   the forces and moments acting on the fish body are thus perfectly balanced.   the fish motion is said to be unstable if a perturbation in the conditions surrounding the fish results in forces and moments that tend to increase the perturbation and it is stable if these emerging forces tend to reduce the perturbation and return the fish to its original state. stability may be achieved actively or passively.   active stabilization requires neurological control that activates musculo - skeletal components to compensate for the external perturbations acting against stability.   passive stabilization on the other hand requires no energy input by the fish and is dependent upon the fish morphology, i.e. geometry and elastic properties. in this paper  , we use a deformable body consisting of an articulated body equipped with torsional springs at its hinge joints and submerged in an unbounded perfect fluid as a simple model to study passive stability as a function of the body geometry and spring stiffness.   we show that for given body dimensions, the spring elasticity, when properly chosen, leads to passive stabilization of the ( otherwise unstable ) coast motion.
the phenomenological parameters of eclipsing binary stars, which are the prototypes of the ea, eb and ew systems are determined using the expert complex of computer programs, which realizes the nav ( `` new algol variable '' ) algorithm ( andronov 2010, 2012 ) and its possible modifications are discussed, as well as constrains for estimates of some physical parameters of the systems in a case of photometric observations only, such as the degree of eclipse, ratio of the mean surface brightnesses of the components.   the half - duration of the eclipse is 0.0617(7 ), 0.1092(18 ) and 0.1015(7 ) for algol, @xmath0 lyrae and w uma, respectively.   the brightness ratio is 6.8@xmath11.0, 4.9@xmath11.0 and 1.15@xmath10.13.   these results show that the eclipses have distinct begin and end not only in ea ( as generally assumed ), but also in eb and ew - type systems as well.   the algorithm may be applied to classification and study of the newly discovered ( or poorly studied ) eclipsing variables based on own observations or that obtained using photometric surveys.   + * key words : * stars, variable stars, binary stars, eclipsing binaries, astroinformatics, data analysis    @xmath2department `` mathematics, physics and astronomy '', odessa national maritime university, mechnikova str., 34, 65029, odessa, ukraine + masha.vodn@yandex.ua, tt_ari@ukr.net + @xmath3 astronomical observatory, odessa national university, marazlievskaia str., 1v, 65014, odessa, ukraine + llchinar
spin - polarized attractive fermi gases in one - dimensional ( 1d ) optical lattices are expected to be remarkably good candidates for the observation of the fulde - ferrell - larkin - ovchinnikov ( fflo ) phase.   we model these systems with an attractive hubbard model with population imbalance. by means of the density - matrix renormalization - group method we compute the pairing correlations as well as the static spin and charge structure factors in the whole range from weak to strong coupling.   we demonstrate that pairing correlations exhibit quasi - long range order and oscillations at the wave number expected from fflo theory. however, we also show by numerically computing the mixed spin - charge static structure factor that charge and spin degrees of freedom appear to be coupled already for small imbalance.   we discuss the consequences of this coupling for the observation of the fflo phase, as well as for the stabilization of the quasi - long range order into long - range order by coupling many identical 1d systems, as in quasi-1d optical lattices.
the integral optical monitoring camera, omc, has detected many high energy sources.   we have obtained v - band fluxes and light curves for their counterparts. in the cases of previously unknown counterparts,   we have searched for characteristic variations in optical sources around the high - energy target position.   results about the galactic bulge monitoring, integral gamma - ray sources ( igr ), and other high energy sources are presented.   = 1    
we investigate the low - temperature properties of the spin-1 antiferromagnetic heisenberg chain with bond - alternation by the quantum monte carlo method ( loop algorithm ).   the strength of bond - alternation at the gapless point is estimated as @xmath0.   we confirm numerically that the low - temperature properties at the gapless point are consistent with field theoretical predictions.   the numerical results are compared with those of the spin-1/2 antiferromagnetic heisenberg chain and recent experimental results for [ \{ni(333-tet)(@xmath1-n@xmath2)}@xmath3(clo@xmath4)@xmath5 ( 333-tet = tetraamine @xmath6-bis(3-aminopropyl)-1,3-propanediamine ).   # 1@xmath7#1
this paper discusses the effect of hubness in zero - shot learning, when ridge regression is used to find a mapping between the example space to the label space.   contrary to the existing approach, which attempts to find a mapping from the example space to the label space, we show that mapping labels into the example space is desirable to suppress the emergence of hubs in the subsequent nearest neighbor search step. assuming a simple data model, we prove that the proposed approach indeed reduces hubness.   this was verified empirically on the tasks of bilingual lexicon extraction and image labeling : hubness was reduced with both of these tasks and the accuracy was improved accordingly.
in this paper we present the mathematical description and analysis of a fractional - order regulated system in the state space.   a little historical background of our results in the analysis and synthesis of the fractional - order dynamical regulated systems is given.   the methods and results of simulations of the fractional - order system described by a state space equation equivalent to three - member fractional - order differential equation with a fractional - order @xmath0 regulator are then presented.   the possibility of investigating the stability of such systems is also considered.   = 10000 = 8000     +   +   +    fractional calculus, fractional - order regulated system, model, state space.
assuming the solar neutrino deficit is resolved by the resonant interaction of the neutrino magnetic moment with the solar magnetic field in the framework of resonant spin flavour precession ( rsfp ) scenario the solar magnetic field profile function has been derived from the scenario in the light of solar neutrino data.   an approximate qualitative analysis has been done for vanishing vacuum mixing and it has been found that the profile derived is quite stable in nature. as because on changing the neutrino parameters ( @xmath0 ) and the solar neutrino data the profile is just scaled along the axes. in principle, the nature of the profile is strongly dependent on the solar matter density distribution function.   the current approach is quite different from the usual one- in which the best field profile is discovered by performing @xmath1 calculations using solar neutrino data.   furthermore, the profile derived in the present work when tested by @xmath1 calculations was found to be the best suited one, for the solar interior.
an overview of the current theoretical studies on neutrino - atom scattering processes is presented.   the ionization channel of these processes, which is studied in experiments searching for neutrino magnetic moments, is brought into focus.   recent developments in the theory of atomic ionization by impact of reactor antineutrinos are discussed.   it is shown that the stepping approximation is well applicable for the data analysis practically down to the ionization threshold.
special features of surface gravity waves in deep fluid flow with constant vertical shear of velocity is studied.   it is found that the mean flow velocity shear leads to non - trivial modification of surface gravity wave modes dispersive characteristics.   moreover, the shear induces generation of surface gravity waves by internal vortex mode perturbations.   the performed analytical and numerical study provides, that surface gravity waves are effectively generated by the internal perturbations at high shear rates.   the generation is different for the waves propagating in the different directions.   generation of surface gravity waves propagating along the main flow considerably exceeds the generation of surface gravity waves in the opposite direction for relatively small shear rates, whereas the later wave is generated more effectively for the high shear rates. from the mathematical point of view the wave generation   is caused by non self - adjointness of the linear operators that describe the shear flow.
pulsars provide unique probes for the _ large - scale _ interstellar magnetic field in the galactic disk.   the parkes multibeam pulsar survey has discovered many distant pulsars which enables us for the first time to explore the magnetic field in most of the nearby half of the galactic disk.   the fields are found to be _ coherent in direction _ over a linear scale of @xmath0 kpc between the carina - sagittarius and crux - scutum arms from @xmath1 to @xmath2.   the coherent spiral structures and field direction reversals, including the newly determined counterclockwise field near the norma arm, are consistent with bi - symmetric spiral model for the disk field. however, the antisymmetric rotation measure sky from the galactic halo and the dipole field in the galactic center suggest that the a0 dynamo is operating there.   # 1 1.25 in.125 in.25 in
we have made subarcsecond - resolution images of the central 10  of the wolf - rayet dwarf galaxy he 2 - 10 at 11.7 microns, using the long wavelength spectrometer on the keck telescope.   the spatial distribution of the infrared emission roughly agrees with that of the rising spectrum radio sources seen by @xcite and confirms that those sources are compact hii regions rather than snr or other objects.   the infrared sources are more extended than the subarcsecond rising spectrum radio sources, although the entire complex is still less than 5  in extent. on sizescales of 1   the infrared and radio emission are in excellent agreement, with each source requiring several hundred to a thousand o stars for excitation.   the nebulae lie in a flattened disk - like distribution about 240 by 100 pc and provide all of the flux measured by iras for the entire galaxy in the 12 micron band ; 30% of the total iras flux from the galaxy emanates from one 15 - 30 pc source. in this galaxy, intense star formation, probably triggered by an accretion event, is confined to a central disk which breaks up into distinct nebulae which presumably mark the sites of young super star clusters.
in this paper, we analyse the bosonic current densities induced by a magnetic flux running along an idealized cosmic string in a high - dimensional spacetime, admitting that the coordinate along the string s axis is compactified.   additionally we admit the presence of an magnetic flux enclosed by the compactification axis. in order to develop this analysis we calculate the complete set of normalized bosonic wave - functions obeying a quasiperiodicity condition, with arbitrary phase @xmath0, along the compactified dimension. in this context,   only azimuthal and axial currents densities take place. as to the azimuthal current, two contributions appear.   the first contribution corresponds to the standard azimuthal current in a cosmic string spacetime without compactification, while the second contribution is a new one, induced by the compactification itself.   the latter is an even function of the magnetic flux enclosed by the string axis and is an odd function of the magnetic flux along its core with period equal to quantum flux, @xmath1. on the other hand  , the nonzero axial current density is an even function of the magnetic flux along the core of the string and an odd function of the magnetic flux enclosed by it.   we also find that the axial current density vanishes for untwisted and twisted bosonic fields in the absence of the magnetic flux enclosed by the string axis.   some asymptotic expressions for the current density are provided for specific limiting cases of the physical parameter of the model.   pacs numbers : 98.80.cq, 11.10.gh, 11.27.+d
here i review recent work, by other authors and by myself, on some particular topics related to the regular and chaotic motion in elliptical galaxies.   i show that it is quite possible to build highly stable triaxial stellar systems that include large fractions of chaotic orbits and that partially and fully chaotic orbits fill different regions of space, so that it is important not to group them together under the single denomination of chaotic orbits.   partially chaotic orbits should not be confused with weakly fully chaotic orbits either, and their spatial distributions are also different. slow figure rotation ( i.e., rotation in systems with zero angular momentum ) seems to be always present in highly flattened models that result from cold collapses, with the rotational velocity diminishing or becoming negligibly small for less flattened models.   finally, i comment on the usefulness and limitations of the classification of regular orbits via frequency analysis.
we have carried out extensive equilibrium molecular dynamics ( md ) simulations to study the structure and the interfacial properties in the liquid - vapor ( lv ) phase coexistence of partially miscible binary lennard - jones ( lj ) mixtures. by analyzing the structural properties as a function of the miscibility parameter, @xmath0  , we found that at relatively low temperatures the system separates forming a liquid a - liquid b interface in coexistence with the vapor phase. at higher temperatures and, @xmath1  , we found a temperature range, @xmath2, where the liquid phases are wet by the vapor phase. here  , @xmath3 represents the wetting transition temperature ( wtt ) and @xmath4 is the consolute temperature of the mixture.   however, for @xmath5, no wetting phenomenon occurs. for the particular value, @xmath6, we analyzed quantitatively the @xmath7 versus @xmath8, and @xmath9 versus @xmath10 phase diagrams and found, @xmath11, and @xmath12.   we also studied quantitatively, as a function of temperature, the surface tension and the adsorption of molecules at the liquid - liquid interface.   it was found that the adsorption shows a jump from a finite negative value up to minus infinity, when the vapor wets the liquid phases, suggesting that the wetting transition ( wt ) is of first order.   the calculated phase diagram together with the wetting phenomenon strongly suggest the existence of a tricritical point.   these results agree well with some experiments carried out in fluid binary mixtures.
a brief review on the physics beyond the standard model is given, as was presented in the high energy particle physics workshop on the @xmath0 of february 2015 at the ithemba north labs.   particular emphasis is given to the minimal supersymmetric standard model, with mention of extra - dimensional theories also.   wits - mitp-008    february 2015
we present the results of direct numerical simulations of flow patterns in a low - prandtl - number ( @xmath0 ) fluid above the onset of oscillatory convection in a rayleigh - bnard system rotating uniformly about a vertical axis.   simulations were carried out in a periodic box with thermally conducting and stress - free top and bottom surfaces.   we considered a rectangular box ( @xmath1 ) and a wide range of taylor numbers ( @xmath2 ) for the purpose.   the horizontal aspect ratio @xmath3 of the box was varied from @xmath4 to @xmath5.   the primary instability appeared in the form of two - dimensional standing waves for shorter boxes ( @xmath6 and @xmath7 ).   the flow patterns observed in boxes with @xmath8 and @xmath9 were different from those with @xmath10 and @xmath7.   we observed a competition between two sets of mutually perpendicular rolls at the primary instability in a square cell ( @xmath8 ) for @xmath11, but observed a set of parallel rolls in the form of standing waves for @xmath12.   the three - dimensional convection was quasiperiodic or chaotic for @xmath13, and then bifurcated into a two - dimensional periodic flow for @xmath14.   the convective structures consisted of the appearance and disappearance of straight rolls, rhombic patterns, and wavy rolls inclined at an angle @xmath15 with the straight rolls.
radio observations suggest that 3c 75, located in the dumbbell shaped galaxy ngc 1128 at the center of abell 400, hosts two colliding jets.   motivated by this source, we perform three - dimensional hydrodynamical simulations using a modified version of the gpu - accelerated adaptive - mesh - refinement hydrodynamical parallel code ( _ gamer _ ) to study colliding extragalactic jets.   we find that colliding jets can be cast into two categories : 1 ) bouncing jets, in which case the jets bounce off each other keeping their identities, and 2 ) merging jets, when only one jet emerges from the collision. under some conditions the interaction causes the jets to break up into oscillating filaments of opposite helicity, with consequences for their downstream stability.   when one jet is significantly faster than the other and the impact parameter is small, the jets merge ; the faster jet takes over the slower one. in the case of merging jets, the oscillations of the filaments, in projection, may show a feature which resembles a double helix, similar to the radio image of 3c 75.   thus we interpret the morphology of 3c 75 as a consequence of the collision of two jets with distinctly different speeds at a small impact parameter, with the faster jet breaking up into two oscillating filaments.
a measure of cluster size heterogeneity ( @xmath0 ), introduced by lee et al [ phys.   rev.   e * 84 *, 020101 ( 2011 ) ] in the context of explosive percolation, was recently applied to random percolation and to domains of parallel spins in the ising and potts models.   it is defined as the average number of different domain sizes in a given configuration and a new exponent was introduced to explain its scaling with the size of the system. in thermal spin models, however, physical clusters take into account the temperature - dependent correlation between neighboring spins and encode the critical properties of the phase transition.   we here extend the measure of @xmath0 to these clusters and, moreover, present new results for the geometric domains for both @xmath1 and 3.   we show that the heterogeneity associated with geometric domains has a previously unnoticed double peak, thus being able to detect both the thermal and percolative transition.   an alternative interpretation for the scaling of @xmath0 that does not introduce a new exponent is also proposed.
we determine the small - scale structure for a large sample of compact steep spectrum ( css ) and gigahertz peaked spectrum ( gps ) sources and a sample of larger radio sources at 327 mhz using the technique of inter - planetary scintillation ( ips ) with the ooty radio telescope.   our observations provide structural information on angular scales ranging from about 50 to a few hundred milliarcsec.   we estimate the size and flux density of the scintillating components from the ips observations.   the fraction of flux density of the hotspots estimated from both the ips observations as well as from interferometric observations for larger sources from the literature exhibits no significant dependence on either the radio luminosity or linear size for the high - luminosity sources.   we examine the collimation of radio jets using the sizes of hotspots from both ips and interferometric observations.   the hotspot sizes do not exhibit a significant dependence on the overall linear size for the larger sources, although the css and gps sources were earlier found to evolve in a self - similar way.   the ips observations show evidence of larger - scale structures compared to the known vlbi - scale structures in 8 css and gps radio sources.   we discuss the origin of these structures.   we also examine the spectra of compact components in gps sources using both ips and interferometric measurements, and attempt to distinguish between different processes for explaining their low - frequency spectra.
antares is the largest neutrino telescope in the northern hemisphere.   the main scientific goal is the search for cosmic neutrinos coming from galactic and extragalactic sources.   neutrinos are detected through the cherenkov light emitted along the path of charged particles produced in neutrino interactions inside or in the vicinity of the detector.   antares is sensitive to all flavors though it is optimized for muon neutrinos.   the detector has been taking data in its complete configuration since may 2008.   using data collected in the period 2007 - 2010, the first analysis devoted to the search for neutrinos from the fermi bubbles is presented.   the fermi bubbles are characterized by gamma emission with a e@xmath0 spectrum and a relatively constant intensity all over the space. according to a proposed hadronic mechanism for this gamma - ray emission  , the fermi bubbles can be a source of high - energy neutrinos.   no evidence of a neutrino signal is found in the antares data.   therefore upper limits are calculated for neutrino fluxes with different energy cutoffs.
class prediction is an important application of microarray gene expression data analysis.   the high - dimensionality of microarray data, where number of genes ( variables ) is very large compared to the number of samples ( observations ), makes the application of many prediction techniques ( e.g., logistic regression, discriminant analysis ) difficult.   an efficient way to solve this problem is by using dimension reduction statistical techniques.   increasingly used in psychology - related applications, rasch model ( rm ) provides an appealing framework for handling high - dimensional microarray data. in this paper  , we study the potential of rm - based modeling in dimensionality reduction with binarized microarray gene expression data and investigate its prediction accuracy in the context of class prediction using linear discriminant analysis.   two different publicly available microarray data sets are used to illustrate a general framework of the approach.   performance of the proposed method is assessed by re - randomization scheme using principal component analysis ( pca ) as a benchmark method.   our results show that rm - based dimension reduction is as effective as pca - based dimension reduction.   the method is general and can be applied to the other high - dimensional data problems.   high - dimensional data, feature extraction, gene expression, class prediction, rasch model 02.70.rr, 07.05.kf, 02.50.sk, 87.18.vf, 87.80.st
we show that existing runge - kutta methods for ordinary differential equations ( odes ) can be modified to solve stochastic differential equations ( sdes ) with strong solutions provided that appropriate changes are made to the way stepsizes are selected.   the order of the resulting sde scheme is half the order of the ode scheme.   specifically, we show that an explicit 9th order runge - kutta method ( with an embedded 8th order method ) for odes yields an order 4.5 method for sdes which can be implemented with variable stepsizes.   this method is tested by solving systems of sdes originating from stochastic wave equations arising from master equations and the many - body schrdinger equation.
we derive the extension of the hubbard model to include rashba spin - orbit coupling that correctly describes aharonov - bohm and aharonov - casher phases in a ring under applied magnetic and electric fields.   when the ring is connected to conducting leads, we develop a formalism that is able to describe both, kondo and interference effects.   we find that in the kondo regime, the spin - orbit coupling reduces strongly the conductance from the unitary limit.   this effect in combination with the magnetic flux, can be used to produce spin polarized carriers.   ,   ,    kondo effect, conductance, spin - orbit coupling, spintronics 73.23.-b, 75.10.jm, 72.25.-b, 71.70.ej
permanent electric dipole moments ( edms ) of elementary particles violate two fundamental symmetries : time reversal invariance ( @xmath0 ) and parity ( @xmath1 ). assuming the @xmath2 theorem this implies @xmath3 violation.   the @xmath3 violation of the standard model is orders of magnitude too small to be observed experimentally in edms in the foreseeable future.   it is also way too small to explain the asymmetry in abundance of matter and anti - matter in our universe.   hence, other mechanisms of @xmath3 violation outside the realm of the standard model are searched for and could result in measurable edms.   up to now most of the edm measurements were done with neutral particles. with new techniques   it is now possible to perform dedicated edm experiments with charged hadrons at storage rings where polarized particles are exposed to an electric field.   if an edm exists the spin vector will experience a torque resulting in change of the original spin direction which can be determined with the help of a polarimeter.   although the principle of the measurement is simple, the smallness of the expected effect makes this a challenging experiment requiring new developments in various experimental areas.   complementary efforts to measure edms of proton, deuteron and light nuclei are pursued at brookhaven national laboratory and at forschungszentrum jlich with an ultimate goal to reach a sensitivity of @xmath4 cm.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
a planet orbiting in the `` habitable zone '' of our closest neighboring star, proxima centauri, has recently been discovered, and the next natural question is whether or not proxima  b ishabitable ".   stellar winds are likely a source of atmospheric erosion that could be particularly severe in the case of m dwarf habitable zone planets that reside close to their parent star. here   we study the stellar wind conditions that proxima  b experiences over its orbit.   we construct 3-d mhd models of the wind and magnetic field around proxima centauri using a surface magnetic field map for a star of the same spectral type and scaled to match the observed @xmath0  g surface magnetic field strength of proxima.   we examine the wind conditions and dynamic pressure over different plausible orbits that sample the constrained parameters of the orbit of proxima  b. for all the parameter space explored, the planet is subject to stellar wind pressures of more than 2000 times those experienced by earth from the solar wind. during an orbit,   proxima  b is also subject to pressure changes of 1 to 3 orders of magnitude on timescales of a day.   its magnetopause standoff distance consequently undergoes sudden and periodic changes by a factor of 2 to 5.   proxima  b will traverse the interplanetary current sheet twice each orbit, and likely crosses into regions of subsonic wind quite frequently.   these effects should be taken into account in any physically realistic assessment or prediction of its atmospheric reservoir, characteristics and loss.   +    = 1
we analyze extragalactic extinction profiles derived through gamma - ray burst afterglows, using a dust model specifically constructed on the assumption that dust grains are not immutable but respond time - dependently to the local physics.   such a model includes core - mantle spherical particles of mixed chemical composition ( silicate core, sp@xmath0 and sp@xmath1 carbonaceous layers ), and an additional molecular component, in the form of free - flying polycyclic aromatic hydrocarbons.   we fit most of the observed extinction profiles.   failures occur for lines of sight presenting remarkable rises blueward the bump.   we find a tendency in the carbon chemical structure to become more aliphatic with the galactic activity, and to some extent with increasing redshifts.   moreover, the contribution of the molecular component to the total extinction is more important in younger objects.   the results of the fitting procedure ( either successes and failures ) may be naturally interpreted through an evolutionary prescription based on the carbon cycle in the interstellar medium of galaxies.
we discuss the hydrodynamics of a wave energy converter consisting of two vertically floating, coaxial cylinders connected by dampers and allowed to heave, sway and roll.   this design, viable in deep water and able to extract energy independent of the incident wave direction, is examined for monochromatic waves as well as broad - banded seas described by a pierson moskowitz spectrum.   several possible device sizes are considered, and their performance is investigated for a design spectrum, as well as for more severe sea states, with a view towards survivability of the converters. in terms of device motions and captured power, a quantitative assessment of converter design as it relates to survival and operation is provided.   most results are given in dimensionless form to allow for a wide range of applications.
harrison s tight - binding theory provides an excellent qualitative description of the electronic structure of the elements across the periodic table  . however, the resulting band structures are in significant disagreement with those found by standard methods, particularly for the transition metals. for these systems we developed a new procedure to generate both the prefactors of harrison s hopping parameters and the onsite energies.   our approach gives an impressive improvement and puts harrison s theory on a quantitative basis.   our method retains the most attractive aspect of the theory, in using a revised set of universal prefactors for the hopping integrals.   in addition, a new form of onsite parameters allows us to describe the lattice constant dependence of the bands and the total energy, predicting the correct ground state for all transition, alkaline earth and noble metals.   this work represents not only a useful computational tool but also an important pedagogical enhancement for harrison s books.   = 6.5 true in = 8.9 true in = 15 pt = 0.1 in
we report rotational periods for 16 young brown dwarfs in the nearby upper scorpius association, based on 72 days of high - cadence, high - precision photometry from the _ kepler _ space telescope s k2 mission.   the periods range from a few hours to two days ( plus one outlier at 5days ), with a median just above one day, confirming that brown dwarfs, except at the very youngest ages, are fast rotators.   interestingly, four of the slowest rotators in our sample exhibit mid - infrared excess emission from disks ; at least two also show signs of disk eclipses and accretion in the lightcurves. comparing these new periods with those for two other young clusters and simple angular momentum evolution tracks, we find little or no rotational braking in brown dwarfs between 1 - 10 myr, in contrast to low - mass stars.   our findings show that disk braking, while still at work, is inefficient in the substellar regime, thus provide an important constraint on the mass dependence of the braking mechanism.
a definition of metastable states applicable to arbitrary finite state markov processes satisfying detailed balance is discussed. in particular  , we identify a crucial condition that distinguishes genuine metastable states from other types of slowly decaying modes and which leads to properties similar to those postulated in the restricted ensemble approach @xcite.   the intuitive physical meaning of this condition is simply that the total equilibrium probability of finding the system in the metastable state is negligible. as a concrete application of our formalism we present preliminary results on a 2d kinetic ising model.
the theories of recoil - induced resonances ( rir ) [ j. guo, p. r. berman, b. dubetsky and g. grynberg, phys. rev.   a * 46 *, 1426 ( 1992 ) ] and the collective atomic recoil laser ( carl ) [ r. bonifacio and l. de salvo, nucl.   instrum.   methods a * 341 *, 360 ( 1994 ) ] are compared.   both theories can be used to derive expressions for the gain experienced by a probe field interacting with an ensemble of two - level atoms that are simultaneously driven by a pump field.   it is shown that the rir and carl formalisms are equivalent.   differences between the rir and carl arise because the theories are typically applied for different ranges of the parameters appearing in the theory.   the rir limit considered in this paper is @xmath0, while the carl limit is @xmath1, where @xmath2 is the magnitude of the difference of the wave vectors of the pump and probe fields, @xmath3 is the width of the atomic momentum distribution and @xmath4 is a recoil frequency. the probe gain for a probe - pump detuning equal to zero is analyzed in some detail, in order to understand how the gain arises in a system which, at first glance, might appear to have vanishing gain.   moreover, it is shown that the calculations, carried out in perturbation theory have a range of applicability beyond the recoil problem.   experimental possibilities for observing carl are discussed.    0.4 in epsf
complementary neutron spin echo and x - ray experiments and molecular dynamics simulations have been performed on difluorotetrachloroethane ( cfcl2-cfcl2 ) glassy crystal.   static, single - molecule reorientational dynamics and collective dynamics properties are investigated.   the orientational disorder is characterized at different temperatures and a change in nature of rotational dynamics is observed.   we show that dynamics can be described by some scaling predictions of the mode coupling theory ( mct ) and a critical temperature @xmath0 is determined.   our results also confirm the strong analogy between molecular liquids and plastic crystals for which @xmath1-relaxation times and non - ergodicity parameters are controlled by the non trivial static correlations as predicted by mct.
we use a quadratic estimator with kl - compression to calculate the angular power spectrum of a volume - limited sloan digital sky survey ( sdss ) data release 7 ( dr7 ) galaxy sample out to @xmath0.   we also determine the angular power spectrum of selected subsamples with photometric redshifts @xmath1 and @xmath2 to examine the possible evolution of the angular power spectrum, as well as early - type and late - type galaxy subsamples to examine the relative linear bias.   in addition, we calculate the angular power spectrum of the sdss dr7 main galaxy sample in a @xmath3 square degree area out to @xmath4 to determine the sdss dr7 angular power spectrum to high multipoles.   we perform a @xmath5 fit to compare the resulting angular power spectra to theoretical nonlinear angular power spectra to extract cosmological parameters and the linear bias.   we find the best - fit cosmological parameters of @xmath6 and @xmath7.   we find an overall linear bias of @xmath8, an early - type bias of @xmath9, and a late - type bias of @xmath10. finally, we present evidence of a selective misclassification of late - type galaxies as stars by the sdss photometric data reduction pipeline in areas of high stellar density ( _ e.g. _, at low galactic latitudes ).   galaxies : statistics  large - scale structure of the universe  methods : data analysis
we theoretically study the interplay between electrical and mechanical properties of suspended, doubly clamped carbon nanotubes in which charging effects dominate. in this geometry,   the capacitance between the nanotube and the gate(s ) depends on the distance between them.   this dependence modifies the usual coulomb models and we show that it needs to be incorporated to capture the physics of the problem correctly.   we find that the tube position changes in discrete steps every time an electron tunnels onto it.   edges of coulomb diamonds acquire a ( small ) curvature.   we also show that bistability in the tube position occurs and that tunneling of an electron onto the tube drastically modifies the quantized eigenmodes of the tube.   experimental verification of these predictions is possible in suspended tubes of sub - micron length.
we present ionization probability and line shape calculations for the two - step 3-photon ionization process, @xmath0, of the ground state of hydrogenic atoms in a non - monochromatic laser field with a time   dependent amplitude. within the framework of a three  level model, the _ ac stark _ shifts and non - zero ionization rates of all states involved   were taken into account together with spatial and temporal inhomogeneities of the laser signal.   in contrast with the usual perturbative technique, the time evolution of the atomic states was simulated by direct numerically solving the system of coupled time   dependent inhomogeneous differential equations, being equivalent to the appropriate non - stationary schrdinger equation.   particular numerical results were obtained for typical parameters of the pulsed laser field that are employed in a new experiment to measure the @xmath1 energy separation in muonium at the rutherford appleton laboratory. the shifts and asymmetries of the photoionization line shapes revealed   may be of relevance for ultra - high precision experiments in hydrogen in cw laser fields.
estimation of the long - term health effects of air pollution is a challenging task, especially when modelling small - area disease incidence data in an ecological study design.   the challenge comes from the unobserved underlying spatial correlation structure in these data, which is accounted for using random effects modelled by a globally smooth conditional autoregressive model.   these smooth random effects confound the effects of air pollution, which are also globally smooth. to avoid this collinearity   a bayesian localised conditional autoregressive model is developed for the random effects.   this localised model is flexible spatially, in the sense that it is not only able to model step changes in the random effects surface, but also is able to capture areas of spatial smoothness in the study region.   this methodological development allows us to improve the estimation performance of the covariate effects, compared to using traditional conditional auto - regressive models.   these results are established using a simulation study, and are then illustrated with our motivating study on air pollution and respiratory ill health in greater glasgow, scotland in 2010.   the model shows substantial health effects of particulate matter air pollution and income deprivation, whose effects have been consistently attenuated by the currently available globally smooth models. +   * keywords : * air pollution and health, conditional autoregressive models, spatial correlation.
a large number ( @xmath010,000 ) of uniform stainless steel balls comprising less than one layer coverage on a vertically shaken plate provides a rich system for the study of excited granular media.   viewed from above, the horizontal motion in the layer shows interesting collective behavior as a result of inelastic particle - particle collisions.   clusters appear as localized fluctuations from purely random density distributions, as demonstrated by increased particle correlations.   the clusters grow as the medium is `` cooled '' by reducing the rate of energy input.   further reduction of the energy input leads to the nucleation of a collapse : a close - packed crystal of particles at rest.   high speed photography allows for measurement of particle velocities between collisions.   the velocity distributions deviate strongly from a maxwell distribution at low accelerations, and show approximately exponential tails, possibly due to an observed cross - correlation between density and velocity fluctuations.   when the layer is confined with a lid, the velocity distributions at higher accelerations are non - maxwellian and independent of the granular temperature.
we study various conceivable photoproduction reactions in a polarized @xmath0 collider mode of hera with respect to their sensitivity to the proton s polarized gluon distribution.   a special emphasis is put on the ` resolved'part of the cross sections which in principle opens the possibility to determine for the first time also the completely unknown parton content of longitudinally polarized photons. in the very promising case of dijet production   we also investigate the impact of parton showering, hadronization and jet finding on the parton level results.   -0.65 cm -0.65 cm    cern - th/97 - 310 + dtp/97/98 + ucl / hep 97 - 08 + november 1997    * abstract *    we study various conceivable photoproduction reactions in a polarized @xmath0 collider mode of hera with respect to their sensitivity to the proton s polarized gluon distribution. a special emphasis is put on the ` resolved'part of the cross sections which in principle opens the possibility to determine for the first time also the completely unknown parton content of longitudinally polarized photons. in the very promising case of dijet production   we also investigate the impact of parton showering, hadronization and jet finding on the parton level results.   contribution to the proceedings of the 1997 workshop on ` physics with polarized protons at hera ', desy - hamburg and desy - zeuthen, march - september 1997.    * photoproduction processes *
coastal transport in the bay of palma, a small region in the island of mallorca, spain, is characterized in terms of lagrangian descriptors.   the data sets used for this study are the output for two months ( one in autumn and one in summer ) of a high resolution numerical model, roms, forced atmospherically and with a spatial resolution of 300 m. the two months were selected because its different wind regime, which is the main driver of the sea dynamics in this area.   finite - size lyapunov exponents ( fsles ) were used to locate semi - persistent lagrangian coherent structures ( lcs ) and to understand the different flow regimes in the bay.   the different wind directions and regularity in the two months have a clear impact on the surface bay dynamics, whereas only topographic features appear clearly in the bottom structures.   the fluid interchange between the bay and the open ocean was studied by computing particle trajectories and residence times ( rt ) maps.   the escape rate of particles out of the bay is qualitatively different, with a 32@xmath0 more of escape rate of particles to the ocean in october than in july, owing to the different geometric characteristics of the flow.   we show that lcss separate regions with different transport properties by displaying spatial distributions of residence times on synoptic lagrangian maps together with the location of the lcss.   correlations between the time - dependent behavior of fsle and rt are also investigated, showing a negative dependence when the stirring characterized by fsle values moves particles in the direction of escape.
recent studies show that an intermediate mass black hole ( imbh ) may develop a dark matter ( dm ) mini - halo according to some bh formation scenarios.   we consider a binary system composed of an imbh surrounded by a dm mini - spike and a stellar mass object orbiting around the imbh.   the binary evolves due to gravitational pull and dynamical friction from the dm mini - spike and back - reaction from its gravitational wave ( gw ) radiation which can be detected by future space - borne gw experiments such as elisa / ngo.   we consider a single power - law model for the dm mini - spike which is assumed to consist of non - annihilating dm particles and demonstrate that an elisa / ngo detection of gw from such a binary enables us to measure the dm mini - spike parameters very accurately.   for instance, in our reference case originally advocated by @xcite ( @xcite ) and @xcite ( @xcite ), we could determine the power - law index @xmath0 of the dm mini - spike radial profile with a 1 @xmath1 relative error of @xmath2 for a gw signal with signal - to - noise - ratio 10 and assuming a 5 year observation with elisa.   we also investigate how accurately the dm parameters can be determined for various dm parameters and the masses of the imbh - stellar mass object binary surrounded by a dm mini - spike.   we find that we can determine the power - law index @xmath0 at 10 % level even for a slightly flatter radial distribution of @xmath3.    1
parametric two - electron reduced - density - matrix ( p-2rdm ) methods have enjoyed much success in recent years ; the methods have been shown to exhibit accuracies greater than coupled cluster with single and double substitutions ( ccsd ) for both closed- and open - shell ground - state energies, properties, geometric parameters, and harmonic frequencies. the class of methods is herein discussed within the context of the coupled electron pair approximation ( cepa ), and several cepa - like topological factors are presented for use within the p-2rdm framework.   the resulting p-2rdm/@xmath0 methods can be viewed as a density - based generalization of cepa/@xmath0 family that are numerically very similar to traditional cepa methodologies.   we cite the important distinction that the obtained energies represent stationary points, facilitating the efficient evaluation of properties and geometric derivatives.   the p-2rdm/@xmath0 formalism is generalized for an equal treatment of exclusion - principle - violating ( epv ) diagrams that occur in the occupied and virtual spaces.   one of these general topological factors is shown to be identical to that proposed by kollmar [ c. kollmar, j. chem.   phys. * 125 *, 084108 ( 2006 ) ], derived in an effort to approximately enforce the @xmath1, @xmath2, and @xmath3 conditions for @xmath4-representability in his size - extensive density matrix functional.
we consider the time - dependent electron transport through a quantum dot coupled to two leads in the presence of the additional over - dot ( bridge ) tunneling channel. by using the evolution operator method together with the wide - band limit approximation we derived the analytical formulaes for the quantum dot charge and current flowing in the system.   the influence of the external microwave field on the time - average quantum dot charge, the current and the derivatives of the average current with respect to the gate and source - drain voltages has been investigated for a wide range of parameters.    * influence of microwave fields on the electron transport + through a quantum dot in the presence of a direct + tunneling between leads + *    institute of physics, m. curie - skodowska university, + 20 - 031 lublin, poland
in the first part of this article, we review the observational evidence for spirals in the accretion discs of cataclysmic variables.   it is shown that with the increasing amount of data available, spirals appear to be an omnipresent feature of accretion discs in outburst.   spirals seem to live until decline that is, for several tens of orbital periods.   we then study the formation of spiral shocks from a theoretical side, using the results of various numerical simulations.   we make a comparison between observations and theory and briefly discuss the implications of the presence of spirals in the discs of cataclysmic variables.   # 1 1.25 in.125 in.25 in
we present a unified model of infrared ( ir ), optical, ultraviolet ( uv ), and x - ray light curves for the 1983 outburst of gq muscae ( nova muscae 1983 ) and estimate its white dwarf ( wd ) mass. based on an optically thick wind model of nova outbursts, we model the optical and ir light curves with free - free emission, and the uv 1455   and supersoft x - ray light curves with blackbody emission.   the best fit model that reproduces simultaneously the ir, optical, uv 1455 , and supersoft x - ray observations is a @xmath0 wd for an assumed chemical composition of the envelope, @xmath1, @xmath2, and @xmath3, by mass weight.   the mass lost by the wind is estimated to be @xmath4.   we provide a new determination of the reddening, @xmath5, and of the distance, @xmath6  kpc.   finally, we discuss the strong uv flash that took place on jd 2,445,499 ( 151 days after the outburst ).
@xmath0  are among the brightest stars observed by _ kepler_.   what makes these stars more interesting is that they are solar analogs.   @xmath0  exhibit solar - like oscillations. in this work   we use oscillation frequencies obtained using 2.5 years of _ kepler _ data to determine the current helium abundance of these stars. for this   we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. by calibrating the signature of the helium ionization zone against models of known helium abundance  , the helium abundance in the envelope of @xmath1  is found to lie in the range 0.231 to 0.251 and that of @xmath2  lies in the range 0.218 to 0.266.
we report a numerical study of self - avoiding polymers on the square lattice, including an attractive potential between nonconsecutive monomers. using wang - landau sampling ( wls ) with adaptive windows,   we obtain the density of states for chains of up to @xmath0 monomers and associated thermodynamic quantities.   the method enables one to simulate accurately the low - temperature regime, which is virtually inaccessible using traditional methods.   instead of defining fixed energy windows, as in usual wls, this method uses windows with boundaries that depend on the set of energy values on which the histogram is flat at a given stage of the simulation. shifting the windows each time the modification factor @xmath1 is reduced, we eliminate border effects that arise in simulations using fixed windows.   lattice polymers, adaptive windows wang - landau sampling
we are designing an all - scintillator compton gamma imager for use in security investigations and remediation actions involving radioactive threat material. to satisfy requirements for a rugged and portable instrument,   we have chosen solid scintillator for the active volumes of both the scatter and absorber detectors. using the beamnrc / egsnrc monte carlo simulation package,   we have constructed models using four different materials for the scatter detector : labr@xmath0, nai, caf@xmath1 and pvt.   we have compared the detector performances using angular resolution, efficiency, and image resolution.   we find that while pvt provides worse performance than that of the detectors based entirely on inorganic scintillators, all of the materials investigated for the scatter detector have the potential to provide performance adequate for our purposes.   shell : bare demo of ieeetran.cls for journals
the connection between the hamilton and the standard lagrange formalism is established for a generic quantum field theory with vanishing vacuum expectation values of the fundamental fields.   the effective actions in both formalisms are the same if and only if the fundamental fields and the momentum fields are related by the stationarity condition.   these momentum fields in general differ from the canonical fields as defined via the effective action. by means of functional methods   a systematic procedure is presented to identify the full correlation functions, which depend on the momentum fields, as functionals of those usually appearing in the standard lagrange formalism. whereas lagrange correlation functions can be decomposed into tree diagrams the decomposition of hamilton correlation functions involves loop corrections similar to those arising in @xmath0-particle effective actions. to demonstrate the method we derive for theories with linearized interactions the propagators of composite auxiliary fields and the ones of the fundamental degrees of freedom.   the formalism is then utilized in the case of coulomb gauge yang - mills theory for which the relations between the two - point correlation functions of the transversal and longitudinal components of the conjugate momentum to the ones of the gauge field are given.
the painlev test is very useful to construct not only the laurent series solutions of systems of nonlinear ordinary differential equations but also the elliptic and trigonometric ones.   the standard methods for constructing the elliptic solutions consist of two independent steps : transformation of a nonlinear polynomial differential equation into a nonlinear algebraic system and a search for solutions of the obtained system.   it has been demonstrated by the example of the generalized hnon   heiles system that the use of the laurent series solutions of the initial differential equation assists to solve the obtained algebraic system.   this procedure has been automatized and generalized on some type of multivalued solutions. to find solutions of the initial differential equation in the form of the laurent or puiseux series we use the painlev test.   this test can also assist to solve the inverse problem : to find the form of a polynomial potential, which corresponds to the required type of solutions.   we consider the five  dimensional gravitational model with a scalar field to demonstrate this.   
the theory of quantum feedback networks has recently been developed with the aim of showing how quantum input - output components may be connected together so as to control, stabilize or enhance the performance of one of the subcomponents. in this paper   we show how the degree to which an idealized component ( a degenerate parametric amplifier in the strong - coupling regime ) can squeeze input fields may be enhanced by placing the component in - loop in a simple feedback mechanism involving a beam splitter.   we study the spectral properties of output fields, placing particular emphasis on the elastic and inelastic components of the power density.
fewster and mistry have given an explicit, non - optimal quantum weak energy inequality that constrains the smeared energy density of dirac fields in minkowski spacetime. here, their argument is adapted to the case of flat, two - dimensional spacetime. the non - optimal bound thereby obtained has the same order of magnitude, in the limit of zero mass, as the optimal bound of vollick.   in contrast with vollick s bound, the bound presented here holds for all ( non - negative ) values of the field mass @xmath0.
* abstract *    we propose a scenario for the formation of localized turbulent spots in transition flows, which is known as resulting from the subcritical character of the transition.   we show that it is not necessary to add  by hand  a term of random noise in the equations, in order to describe the existence of long wavelength fluctuations as soon as the bifurcated state is beyond the benjamin - feir instability threshold.   we derive the instability threshold for generalized complex ginzburg - landau equation which displays subcriticality. beyond and   close to the benjamin - feir threshold we show that the dynamics is mainly driven by the phase of the complex amplitude which obeys kuramoto - sivashinsky equation while the fluctuations of the modulus are smaller and slaved to the phase ( as already proved for the supercritical case ). on the opposite, below the benjamin - feir instability threshold,   the bifurcated state does loose the randomness associated to turbulence so that the transition becomes of the mean - field type as in noiseless reaction - diffusion systems and leads to pulse - like patterns.
we present a deep bvri multicolor catalog of galaxies in a 5.62 sq.arcmin field 80 arcsec south of the high redshift ( @xmath0 ) quasar br 1202 - 0725, derived from observations with the direct ccd camera susi at the eso ntt.   the formal 5@xmath1 magnitude limits ( in @xmath2 fwhm apertures ) are 26.9, 26.5, 25.9 and 25.3 in b, v, r and i respectively. counts, colors for the star and galaxy samples are discussed and a comparison with a deep hst image in the i band is presented.   the percentage of merged or blended galaxies in the susi data to this magnitude limit is estimated to be not higher than 1%.    at the same galactic latitude of the hdf but pointing toward the galactic center  , the star density in this field is found to be @xmath3 times higher, with @xmath4 of the objects with v - i@xmath53.0.   reliable colors have been measured for galaxies selected down to @xmath6.   the choice of the optical filters has been optimized to define a robust multicolor selection of galaxies at @xmath7. within this interval   the surface density of galaxy candidates with @xmath8 in this field is @xmath9 arcmin@xmath10 corresponding to a comoving density of star formation rate at @xmath11 of @xmath12.
= 0.6 cm    * abstract *    the holographic model for a two - dimensional superconductor has been investigated by considering the three - dimensional gravity in the bulk. to find the critical temperature, we used the sturm - liouville variational method.   where as the same method is applied for calculating the condensation of the dual operators on the boundary.   we included the back reactions on the metric by a combination of the perturbation method of the fields with respect to the small parameter and then applying the variational integrals on the resulting equations of the motion.   the critical temperature has been successfully obtained on the backreaction effects, and we showed that it dropped with a rise in the backreaction of the fields, and it makes the condensation harder.   we can use our analytical results to support the numerical data which was reported previously.   = 0.8 cm
we analyse the parallel hybrid texture structures in the charged lepton and the neutrino sector.   these parallel hybrid texture structures have physical implications as they can not be obtained from arbitrary lepton mass matrices through weak basis transformations.   the total sixty parallel hybrid texture structures can be grouped into twelve classes, and all the hybrid textures in the same class have identical physical implications.   we examine all the twelve classes under the assumption of non - factorizable phases in the neutrino mass matrix.   five out of the total twelve classes are found to be phenomenologically disallowed.   we study the phenomenological implications of the allowed classes for 1 - 3 mixing angle, majorana and dirac - type @xmath0 violating phases.   interesting constraints on effective majorana mass are obtained for all the allowed classes.
we use distribution amplitudes of the light @xmath0 baryon and the most general form of the interpolating current for heavy @xmath1 baryon to investigate the semileptonic @xmath2 transition in light cone qcd sum rules.   we calculate all twelve form factors responsible for this transition and use them to evaluate the branching ratio of the considered channel.   the order of branching fraction shows that this channel can be detected at lhc.    # 1#2#3    @xmath3        #   1#2#3    @xmath3        0^*0 5_5    o _ ^0 _    pacs number(s ) : 11.55.hx, 13.30.-a, 13.30.ce, 14.20.mr
in this paper, a new quantum mechanical method to extract energy from black holes with contracting horizons is proposed.   the method is based on a gedanken experiment on quantum energy teleportation ( qet ), which has been recently proposed in quantum information theory.   we consider this qet protocol for n massless fields in near - horizon regions of large - mass black holes with near - horizon geometry described by the minkowski metric.   for each field, a two - level spin is strongly coupled with the local quantum fluctuation outside the horizon during a short time period.   after the measurement of n fields, n - bit information is obtained. during the measurement, positive - energy wave packets of the fields form and then fall into the black hole.   the amount of excitation energy is independent of the measurement result.   after absorption of the wave packets and increase of the black hole mass, a measurement - result - dependent local operation of the n fields is performed outside the horizon.   then, accompanying the extraction of positive energy from the quantum fluctuation by the operation, negative - energy wave packets of the fields form and then fall into the black hole, decreasing the black hole mass.   this implies that a part of the absorbed positive energy emitted from the measurement devices is effectively retrieved from the black hole via the measurement results.   +     +     +   +   + _ department of physics, faculty of science, tohoku university, + sendai 980 - 8578, japan + hotta@tuhep.phys.tohoku.ac.jp_
quantum fisher information is a key concept in the field of quantum metrology, which aims to enhance the accuracy of parameter estimation by using quantum resources. in this paper, utilizing a representation of quantum fisher information for a general unitary parametrization process, we study unitary parametrization processes governed by su(2 ) dynamics.   we obtain the analytical expression for the hermitian operator of the parametrization and the maximal quantum fisher information.   we find that the maximal quantum fisher information over the parameter space consists of two parts ; one is quadratic in time and the other oscillates with time.   we apply our result to the estimation of a magnetic field and obtained the maximal quantum fisher information.   we further discuss a driving field with a time - dependent hamiltonian and find that the maximal quantum fisher information of the driving frequency attains the optimum when it is in resonance with the atomic frequency.
we focus on the propagation properties of a single - cycle laser pulse through a two - level medium by numerically solving the full - wave maxwell - bloch equations.   the counter - rotating terms in the spontaneous emission damping are included such that the equations of motion are slightly different from the conventional bloch equations.   the counter - rotating terms can considerably suppress the broadening of the pulse envelope and the decrease of the group velocity rooted from dispersion.   furthermore, for incident single - cycle pulses with envelope area 4@xmath0, the time - delay of the generated soliton pulse from the main pulse depends crucially on the carrier - envelope phase of the incident pulse.   this can be utilized to determine the carrier - envelope phase of the single - cycle laser pulse.
we develop a uniform semiclassical trace formula for the density of states of a three - dimensional isotropic harmonic oscillator ( ho ), perturbed by a term @xmath0.   this term breaks the u(3 ) symmetry of the ho, resulting in a spherical system with so(3 ) symmetry.   we first treat the anharmonic term for small @xmath1 in semiclassical perturbation theory by integration of the action of the perturbed periodic ho orbit families over the manifold @xmath2p@xmath3 which is covered by the parameters describing their four - fold degeneracy.   then we obtain an analytical uniform trace formula for arbitrary @xmath1 which in the limit of strong perturbations ( or high energy ) asymptotically goes over into the correct trace formula of the full anharmonic system with so(3 ) symmetry, and in the limit @xmath1 ( or energy ) @xmath4 restores the ho trace formula with u(3 ) symmetry.   we demonstrate that the gross - shell structure of this anharmonically perturbed system is dominated by the two - fold degenerate diameter and circular orbits, and _ not _ by the orbits with the largest classical degeneracy, which are the three - fold degenerate tori with rational ratios @xmath5 of radial and angular frequencies.   the same holds also for the limit of a purely quartic spherical potential @xmath6.
this article presents an on - line tool and its accompanying software resources for the numerical solution of basic radiation transfer out of local thermodynamic equilibrium ( lte ).   state - of - the - art stationary iterative methods such as accelerated @xmath0iteration and gauss - seidel schemes, using a short characteristics - based formal solver are used.   we also comment on typical numerical experiments associated to the basic non  lte radiation problem.   these resources are intended for the largest use and benefit, in support to more classical radiation transfer lectures usually given at the master level.
a new extension of the attractive hubbard model is constructed to study the critical behavior near a finite temperature superconducting phase transition in two dimensions using the recently developed meron - cluster algorithm. unlike previous calculations in the attractive hubbard model which were limited to small lattices,   the new algorithm is used to study the critical behavior on lattices as large as @xmath0.   these precise results for the first time show that a fermionic system can undergo a finite temperature phase transition whose critical behavior is well described by the predictions of kosterlitz and thouless almost three decades ago. in particular it is confirmed that the spatial winding number susceptibility obeys the well known predictions of finite size scaling for @xmath1 and up to logarithmic corrections the pair susceptibility scales as @xmath2 at large volumes with @xmath3 for @xmath4.
we investigate the effects of scalar and vector unparticles on top quark spin correlations via the process @xmath0.   in addition to the standard model diagrams, there is a new contribution to top - antitop quark production process mediated by unparticle in the s - channel.   it is shown that scalar and vector unparticle contribution leads to a considerable deviation of the top spin correlations from the standard model one.
we analyze the possible existence of a pulsational instability excited by the @xmath0-mechanism during the last few centuries of evolution of a chandrasekhar mass white dwarf prior to its explosion as a type ia supernova.   our analysis is motivated by the temperature sensitivity of the nuclear energy generation rate ( @xmath1 ) in a white dwarf whose structural adiabatic index is near 4/3.   based upon a linear stability analysis, we find that the fundamental mode and higher order radial modes are indeed unstable and that the fundamental mode has the shortest growth time scale.   however, the growth time scale for such instability never becomes shorter than the evolutionary timescale.   therefore, even though the star _ is _ pulsationally unstable, we do not expect these radial modes to have time to grow and to affect the structure and explosion properties of type ia supernovae.
cooperative spontaneous emission of a single photon from a cloud of @xmath0 atoms modifies substantially the radiation pressure exerted by a far - detuned laser beam exciting the atoms. on one hand,   the force induced by photon absorption depends on the collective decay rate of the excited atomic state. on the other hand,   directional spontaneous emission counteracts the recoil induced by the absorption.   we derive an analytical expression for the radiation pressure in steady - state. for a smooth extended atomic distribution   we show that the radiation pressure depends on the atom number via cooperative scattering and that, for certain atom numbers, it can be suppressed or enhanced.   cooperative scattering of light by extended atomic clouds can become important in the presence of quasi - resonant light and could be addressed in many cold atoms experiments.
the principal paradigm for the generation of the non - thermal particles that are responsible for the prompt emission of gamma - ray bursts invokes diffusive shock acceleration at shocks internal to the dynamic ultrarelativistic outflow.   this paper explores expectations for burst emission spectra arising from shock acceleration theory in the limit of particles cooling much slower than their acceleration.   parametric fits to burst spectra obtained by the compton gamma - ray observatory ( cgro ) are explored for the cases of the synchrotron, inverse compton and synchrotron self - compton radiation mechanisms, using a linear combination of thermal and non - thermal electron populations.   these fits demand that the preponderance of electrons that are responsible for the prompt emission reside in an intrinsically non - thermal population, strongly contrasting particle distributions obtained from acceleration simulations.   this implies a potential conflict for acceleration scenarios where the non - thermal electrons are drawn directly from a thermal gas, unless radiative efficiencies only become significant at highly superthermal energies.   it is also found that the cgro data preclude effective spectroscopic discrimination between the synchrotron and inverse compton mechanisms.   this situation may be resolved with future missions probing gamma - ray bursts, namely swift and glast.   however, the synchrotron self - compton ( ssc ) spectrum is characteristically too broad near the peak to viably account for bursts such as grb 910601, grb 910814 and grb 990123.   it is concluded that the ssc mechanism may be generally incompatible with differential burst spectra steeper than around above the peak, unless the synchrotron component is strongly self - absorbed.
in this investigation we study extreme vortex states defined as incompressible velocity fields with prescribed enstrophy @xmath0 which maximize the instantaneous rate of growth of enstrophy @xmath1.   we provide an analytic characterization of these extreme vortex states in the limit of vanishing enstrophy @xmath0 and, in particular, show that the taylor - green vortex is in fact a local maximizer of @xmath2 in this limit. for finite values of enstrophy,   the extreme vortex states are computed numerically by solving a constrained variational optimization problem using a suitable gradient method. in combination with a continuation approach,   this allows us to construct an entire family of maximizing vortex states parameterized by their enstrophy.   we also confirm the findings of the seminal study by @xcite that these extreme vortex states saturate ( up to a numerical prefactor ) the fundamental bound @xmath3, for some constant @xmath4.   the time evolution corresponding to these extreme vortex states leads to a larger growth of enstrophy than the growth achieved by any of the commonly used initial conditions with the same enstrophy @xmath0.   however, based on several different diagnostics, there is no evidence of any tendency towards singularity formation in finite time.   finally, we discuss possible physical reasons why the initially large growth of enstrophy is not sustained for longer times.   keywords : navier - stokes equations ; extreme behaviour ; variational methods ; vortex flows
different characteristic of matter influencing the evolution of the universe has been simulated by means of a nonlinear spinor field.   exploiting the spinor description of perfect fluid and dark energy evolution of the universe given by an anisotropic bianchi type - vi, vi@xmath0, v, iii, i or isotropic friedmann - robertson - walker ( frw ) one has been studied.   it is shown that due to some restrictions on metric functions, initial anisotropy in the models bianchi type - vi, vi@xmath0, v and iii does not die away, while the anisotropic bianchi type - i models evolves into the isotropic one.    -24pt
making use of a droplet - epitaxial technique, we realize nanometer - sized quantum ring complexes, consisting of a well - defined inner ring and an outer ring.   electronic structure inherent in the unique quantum system is analyzed using a micro - photoluminescence technique.   one advantage of our growth method is that it presents the possibility of varying the ring geometry.   two samples are prepared and studied : a single - wall ring and a concentric double - ring. for both samples, highly efficient photoluminescence emitted from a single quantum structure   is detected.   the spectra show discrete resonance lines, which reflect the quantized nature of the ring - type electronic states. in the concentric double  ring, the carrier confinement in the inner ring and that in the outer ring are identified distinctly as split lines.   the observed spectra are interpreted on the basis of single electron effective mass calculations.
we present high resolution simulations on the impact of ionizing radiation of massive o - stars on the surrounding turbulent interstellar medium ( ism ).   the simulations are performed with the newly developed software ivine which combines ionization with smoothed particle hydrodynamics ( sph ) and gravitational forces.   we show that radiation from hot stars penetrates the ism, efficiently heats cold low density gas and amplifies over - densities seeded by the initial turbulence.   the formation of observed pillar - like structures in star forming regions ( e.g. in m16 ) can be explained by this scenario. at the tip of the pillars gravitational collapse   can be induced, eventually leading to the formation of low mass stars.   detailed analysis of the evolution of the turbulence spectra shows that uv - radiation of o - stars indeed provides an excellent mechanism to sustain and even drive turbulence in the parental molecular cloud.    `   gritschm@usm.uni-muenchen.de ` +
in supersymmetric extensions of the standard model there is no basic difference between higgs and matter fields, which leads to the well known problem of potentially large baryon and lepton number violating interactions. although these unwanted couplings can be forbidden by continuous or discrete global symmetries, a theoretical guiding principle for their choice is missing.   we examine this problem for a class of vacua of the heterotic string compactified on an orbifold.   as expected, in general there is no difference between higgs and matter.   however, certain vacua happen to possess unbroken matter parity and discrete @xmath0-symmetries which single out higgs fields in the low energy effective field theory.   we present a method how to identify maximal vacua in which the perturbative contribution to the @xmath1-term and the expectation value of the superpotential vanish.   two vacua are studied in detail, one with two pairs of higgs doublets and one with partial gauge - higgs unification.
experimental studies on enzyme evolution show that only a small fraction of all possible mutation trajectories are accessible to evolution. however, these experiments deal with individual enzymes and explore a tiny part of the fitness landscape.   we report an exhaustive analysis of fitness landscapes constructed with an off - lattice model of protein folding where fitness is equated with robustness to misfolding.   this model mimics the essential features of the interactions between amino acids, is consistent with the key paradigms of protein folding and reproduces the universal distribution of evolutionary rates among orthologous proteins.   we introduce mean path divergence as a quantitative measure of the degree to which the starting and ending points determine the path of evolution in fitness landscapes.   global measures of landscape roughness are good predictors of path divergence in all studied landscapes : the mean path divergence is greater in smooth landscapes than in rough ones.   the model - derived and experimental landscapes are significantly smoother than random landscapes and resemble additive landscapes perturbed with moderate amounts of noise ; thus, these landscapes are substantially robust to mutation.   the model landscapes show a deficit of suboptimal peaks even compared with noisy additive landscapes with similar overall roughness.   we suggest that smoothness and the substantial deficit of peaks in the fitness landscapes of protein evolution are fundamental consequences of the physics of protein folding.
we have obtained intermediate - resolution vlt spectroscopy of 75 globular cluster candidates around the sa galaxy m104 ( ngc4594 ).   fifty - seven candidates out to @xmath0 kpc in the halo of the galaxy were confirmed to be bona - fide globular clusters, 27 of which are new.   a first analysis of the velocities provides only marginal evidence for rotation of the cluster system. from h@xmath1 line strengths, almost all of the clusters in our sample have ages that are consistent, within the errors, with milky way globular clusters.   only a few clusters may be 12 gyr old, and bulge and halo clusters appear coeval.   the absorption line indices follow the correlations established for the milky way clusters.   metallicities are derived based upon new empirical calibrations with galactic globular clusters taking into account the non - linear behavior of some indices ( e.g., mg2 ).   our sample of globular clusters in ngc4594 spans a metallicity range of @xmath2 } < + 0.26 $ ] dex, and the median metallicity of the system is @xmath3.   thus, our data provide evidence that some of the clusters have super - solar metallicity.   overall, the abundance distribution of the cluster system is consistent with a bimodal distribution with peaks at @xmath4 and @xmath5.   however, the radial change in the metallicity distribution of clusters may not be straightforwardly explained by a varying mixture of two sub - populations of red and blue clusters.
the interaction of high intensity laser radiation with mass - limited target exhibits significant enhancement of the ion acceleration when the target is surrounded by an underdense plasma corona, as seen in numerical simulations.   the self - generated quasistatic magnetic field squeezes the corona causing the intensification of a subsequent coulomb explosion of the target.   the electric field intensification at the target edges and plasma resonance effects result in the generation of characteristic density holes and further contributes to the ion acceleration.   keywords : relativistic laser plasmas, ion acceleration, quasi - static magnetic field, particle - in - cell simulation
at future linear @xmath0 collider experiments in the tev range, sudakov double logarithms originating from massive boson exchange can lead to significant corrections to the cross sections of the observable processes.   these effects are important for the high precision objectives of the next linear collider.   we use the infrared evolution equation, based on a gauge invariant dispersive method, to obtain double logarithmic asymptotics of scattering amplitudes and discuss how it can be applied, in the case of broken gauge symmetry, to the standard model of electroweak processes.   we discuss the double logarithmic effects to both non - radiative processes and to processes accompanied by soft gauge boson emission. in all cases   the sudakov double logarithms are found to exponentiate.   we also discuss double logarithmic effects of a non - sudakov type which appear in regge - like processes.    hep - ph/9910338 + dtp/99/94 + psi pr-99 - 24 + october 1999 +     +   + 1 ) budker institute of nuclear physics and novosibirsk state university, 630090 novosibirsk, russia +    \2 ) st.   petersburg nuclear physics institute, 188350 and st.   petersburg state + university, st.   petersburg, russia +    \3 ) department of physics, university of durham, durham, dh1 3le, uk +    \4 ) paul scherrer institute ( psi ), ch-5232 villigen, switzerland.
variation of intensity of the flux at the cores of large features and spectral lines of the classical magnetic cp star @xmath0  cvn in the ultraviolet spectral region from 1150 to 3200    is investigated.   this study is based on the archival _ international ultraviolet explorer _   data obtained at different phases of the rotational cycle.   the shapes of two light curves at @xmath1  1375 and 1415    at the core of large feature at @xmath2  1400    curves significantly differ.   the light curve at @xmath2  1375    show similar shape as in the pseudo - continuum. the same behavior of the flux is at the cores of si  ii resonance lines at @xmath1  126064 and 1485  .   while, the light curve at @xmath2  1415    show the phase displacement of minimum of the flux. the phase displacement also is presented at the cores of si  ii resonance lines at @xmath1  130409 and 1485  . the minimal values of the amplitude of the flux variations are reached at the cores of the large features at @xmath1  1560 and 1770   and at the cores of the strong si  ii resonance lines.   the flux at the cores of large feature at @xmath2  1770    and fe  ii resonance line at @xmath2  172531  , within errors measurements, does not vary.   the investigation of variability of the flux in the wings of @xmath3 line indicate that the fluxes, which formed in inner layers of atmosphere, are redistributed into outer layers of atmosphere of @xmath0  cvn.
we study the zero - bias magnetoresistance ( @xmath0 ) of an interacting quantum dot connected to two ferromagnetic leads and capacitively coupled to a gate voltage source @xmath1.   we investigate the effects of the spin - activity of the contacts between the dot and the leads by introducing an effective exchange field in an anderson model.   this spin - activity makes easier negative @xmath0 effects, and can even lead to a giant @xmath0  effect with a sign tunable with @xmath1. assuming a twofold orbital degeneracy, our approach allows to interpret in an interacting picture the @xmath2 measured by s. sahoo _ _  et al. _ _  in single wall carbon nanotubes with ferromagnetic contacts.   if this experiment is repeated on a larger @xmath3range, we expect that the @xmath4 oscillations are not regular like in the presently available data, due to coulomb interactions.
we study the axion monodromy inflation with a non - perturbatively generated sinusoidal term.   the potential form is a mixture between the natural inflation and the axion monodromy inflation potentials.   the sinusoidal term is subdominant in the potential, but leaves significant effects on the resultant fluctuation generated during inflation.   a larger tensor - to - scalar ratio can be obtained in our model.   we study two scenarios, the single inflation scenario and the double inflation scenario. in the first scenario,   the axion monodromy inflation with a sufficient number of e - folds generates a larger tensor - to - scalar ratio of about 0.1 - 0.15 but also a tiny running of the spectral index. in the second scenario of double inflation,   axion monodromy inflation is its first stage, and we assume another inflation follows. in this case, our model can realize a larger tensor - to - scalar ratio and a large negative running of the spectral index simultaneously.
a local exclusion principle is observed for identical particles obeying intermediate / fractional exchange statistics in one and two dimensions, leading to bounds for the kinetic energy in terms of the density.   this has implications for models of lieb - liniger and calogero - sutherland type, and implies a non - trivial lower bound for the energy of the anyon gas whenever the statistics parameter is an odd numerator fraction.   we discuss whether this is actually a necessary requirement.
wise j085510.83@xmath0071442.5 was recently discovered as the coldest known brown dwarf based on four epochs of images from the _ wide - field infrared survey explorer _ and the _ spitzer space telescope_. we have improved the accuracy of its parallax measurement by obtaining two additional epochs of _ spitzer _ astrometry.   we derive a parallactic distance of 2.31@xmath10.08  pc, which continues to support its rank as the fourth closest known system to the sun when compared to wise j104915.57@xmath0531906.1  ab ( 2.02@xmath10.02  pc ) and wolf 359 ( 2.386@xmath10.012  pc ).   the new constraint on the absolute magnitude at 4.5  indicates an effective temperature of 235260  k based on four sets of theoretical models.   we also show the updated positions of wise j085510.83@xmath0071442.5 in two color - magnitude diagrams. whereas faherty and coworkers cited its location in @xmath2 versus @xmath3 as evidence of water clouds, we find that those data can be explained instead by cloudless models that employ non - equilibrium chemistry.
we investigate existence, uniqueness, and the asymptotic properties of constant mean curvature ( cmc ) slicings in vacuum kantowski - sachs spacetimes with positive cosmological constant.   since these spacetimes violate the strong energy condition, most of the general theorems on cmc slicings do not apply.   although there are in fact kantowski - sachs spacetimes with a unique cmc foliation or cmc time function, we prove that there also exist kantowski - sachs spacetimes with an arbitrary number of ( families of ) cmc slicings.   the properties of these slicings are analyzed in some detail.   keywords :    constant mean curvature   cmc slicing   cmc foliation  cosmological constant  kantowski - sachs  schwarzschild - de sitter
surface level instability when tube is injected into vibrating bed of powder, which was originally found in experiments, is investigated numerically.   we find that thicker ( thiner ) tube makes surface level inside tube higher ( lower ) than surface level outside tube. with fixed acceleration amplitude of vibration,   surface level inside tube becomes higher as amplitude of vibration increases, which can be explained by considering the dependence upon strength of convective flow.
a set - up is introduced which can be superimposed onto the existing solar flare cellular automata ( ca ) models, and which specifies the interpretation of the model s variables.   it extends the ca models, yielding the magnetic field, the current, and an approximation to the electric field, in a way that is consistent with maxwell s and the mhd equations.   applications to several solar flare ca models during their natural state ( self - organized criticality ( soc ) ) show, among others, that ( 1 ) the magnetic field exhibits _ characteristic large - scale organization _ over the entire modeled volume ; ( 2 ) the magnitude of the current seems spatially dis - organized, with no obvious tendency towards large - scale structures or even local organization ; ( 3 ) bursts occur at sites with increased current, and after a burst the current is relaxed ; ( 4 ) by estimating the energy released in individual bursts with the use of the current as ohmic dissipation, it turns out that the power - law distributions of the released energy persist.   the ca models, extended with the set - up, can thus be considered as _   models for energy - release through current - dissipation_. the concepts of power - law loading and anisotropic events ( bursts ) in ca models are generalized to 3d vector - field models, and their effect on the magnetic field topology is demonstrated  .    = cmr8 = cmcsc10    = ~      # 1#1
given the unique optical properties of lif, it is often used as an observation window in high - temperature and pressure experiments ; and, hence, estimates of its transmission properties are necessary to interpret observations. since direct measurements of the thermal conductivity of lif at the appropriate conditions are difficult, we resort to molecular simulation methods. using an empirical potential validated against _ ab initio _ phonon density of states  , we estimate the thermal conductivity of lif at high temperatures ( 10004000k ) and pressures ( 100400 gpa ) with the green - kubo method.   we also compare these estimates to those derived directly from _ ab initio _ data. to ascertain the correct phase of lif at these extreme conditions we calculate the ( relative ) phase stability of the b1 and b2 structures using a quasiharmonic _ ab initio _ model of the free energy.   we also estimate the thermal conductivity of lif in an uniaxial loading state that emulates initial stages of compression in high - stress ramp loading experiments and show the degree of anisotropy induced in the conductivity due to deformation.
recent asca observations of g347.3@xmath00.5, an snr discovered in the rosat all - sky survey, reveal nonthermal emission from a region along the northwestern shell ( koyama _ et  al.   _ 1997 ). here   we report on new pointed asca observations of g347.3@xmath0.5 which confirm this result for all the bright shell regions and also reveal similar emission, although with slightly different spectral properties, from the remainder of the snr.   curiously, no thermal x - ray emission is detected anywhere in the remnant.   we derive limits on the amount of thermal emitting material present in g347.3@xmath00.5 and present new radio continuum, co and infrared results which indicate that the remnant is distant and of moderate age. we show that our observations are broadly consistent with a scenario that has most of the supernova remnant shock wave still within the stellar wind bubble of its progenitor star, while part of it appears to be interacting with denser material.   a point source at the center of the remnant has spectral properties similar to those expected for a neutron star and may represent the compact relic of the supernova progenitor.   = 10001
the estimation of cosmological parameters from cosmic microwave experiments has almost always been performed assuming gaussian data. in this paper the sensitivity of the parameter estimation to different assumptions on the probability distribution of the fluctuations is tested.   specifically, adopting the edgeworth expansion, i show how the cosmological parameters depend on the skewness of the @xmath0 spectrum. in the particular case of skewness independent of @xmath1   i find that the primordial slope, the baryon density and the cosmological constant increase with the skewness.
we present several coupled - cluster calculations of ground and excited states of @xmath0he and @xmath1o employing methods from quantum chemistry.   a comparison of coupled cluster results with the results of exact diagonalization of the hamiltonian in the same model space and other truncated shell - model calculations shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei, with much less computational effort than traditional large - scale shell - model approaches. unless truncations are made, for nuclei like @xmath1o, full - fledged shell - model calculations with four or more major shells are not possible.   however, these and even larger systems can be studied with the coupled cluster methods due to the polynomial rather than factorial scaling inherent in standard shell - model studies.   this makes the coupled cluster approaches, developed in quantum chemistry, viable methods for describing weakly bound systems of interest for future nuclear facilities.
we adopt @xmath0 distance as eve s distinguishability in secret key generation from a common random number without communication. under this secrecy criterion, using the rnyi entropy of order @xmath1 for @xmath2 $ ], we derive a new upper bound of eve s distinguishability under the application of the universal@xmath3 hash function.   it is also shown that this bound gives the tight exponential rate of decrease in the independent and identical distribution.   the result is applied to wire - tap channel model and secret key distillation ( agreement ) by public discussion.   sacrifice bits, @xmath0 norm distance, secret key distillation, universal hash function, wire - tap channel
in this article i review the origin and the effects of chirally enhanced loop - corrections in the mssm based on refs.  @xcite.   chiral enhancement is related to fermion - higgs couplings ( or self - energies when the higgs field is replaced by its vev ).   i describe the resummation of these chirally - enhanced corrections to all orders in perturbation theory and the calculation of the effective fermion - higgs and gaugino(higgsino)-fermion vertices. as an application a model with radiative flavor - violation   is discussed which can solve the susy - cp and the susy - flavor problem while it is still capable of explaining the observed deviation from the sm in the @xmath0mixing phase.   [ 1999/12/01 v1.4c il   nuovo cimento ]
a light echo around sn 1993j was observed 8.2 years after explosion by a hst wfpc2 observation, adding to the small family of supernovae with light echoes.   the light echo was formed by supernova light scattered from a dust sheet, which lies 220 parsecs away from the supernova, 50 parsecs thick along the line of sight, as inferred from radius and width of the light echo.   the dust inferred from the light echo surface brightness is 1000 times denser than the intercloud dust.   the graphite to silicate fraction can not be determined by our bvi photometric measurements, however, a pure graphite model can be excluded based on comparison with the data. with future observations  , it will be possible to measure the expansion rate of the light echo, from which an independent distance to m81 can be obtained.
an approximation to the added mass matrix of an assembly of spheres is constructed on the basis of potential flow theory for situations where one sphere is much larger than the others. in the approximation the flow potential near a small sphere   is assumed to be dipolar, but near the large sphere it involves all higher order multipoles. the analysis is based on an exact result for the potential of a magnetic dipole in the presence of a superconducting sphere. subsequently, the approximate added mass hydrodynamic interactions are used in a calculation of the swimming velocity and rate of dissipation of linear chain structures consisting of a number of small spheres and a single large one, with account also of frictional hydrodynamic interactions.   the results derived for periodic swimming on the basis of a kinematic approach are compared with bilinear theory, valid for small amplitude of stroke, and with the numerical solution of the approximate equations of motion.   the calculations cover the whole range of scale number between the friction - dominated stokes limit and the inertia - dominated regime.
fourier - domain difference map ( fdm ) for phase retrieval with two oversampled coded diffraction patterns are proposed.   fdm is a 3-parameter family of fixed point algorithms including fourier - domain hybrid - projection - reflection ( fhpr ) and douglas - rachford ( fdr ) algorithm. for generic complex objects without any object constraint,   fdm yields a unique fixed point, after proper projection back to the object domain, that is the true solution to the phase retrieval problem up to a global phase factor.
by using a correlated many body method and using the realistic van der waals potential we study several statistical measures like the specific heat, transition temperature and the condensate fraction of the interacting bose gas trapped in an anharmonic potential. as the quadratic plus a quartic confinement makes the trap more tight, the transition temperature increases which makes more favourable condition to achieve bose - einstein condensation ( bec ) experimentally.   bec in 3d isotropic harmonic potential is also critically studied, the correction to the critical temperature due to finite number of atoms and also the correction due to inter - atomic interaction are calculated by the correlated many - body method.   comparison and discussion with the mean - field results are presented.
homophily and social influence are the fundamental mechanisms that drive the evolution of attitudes, beliefs and behaviour within social groups.   homophily relates the similarity between pairs of individuals attitudinal states to their frequency of interaction, and hence structural tie strength, while social influence causes the convergence of individuals states during interaction.   building on these basic elements, we propose a new mathematical modelling framework to describe the evolution of attitudes within a group of interacting agents.   specifically, our model describes sub - conscious attitudes that have an activator - inhibitor relationship.   we consider a homogeneous population using a deterministic, continuous - time dynamical system.   surprisingly, the combined effects of homophily and social influence do not necessarily lead to group consensus or global monoculture.   we observe that sub - group formation and polarisation - like effects may be transient, the long - time dynamics being quasi - periodic with sensitive dependence to initial conditions.   this is due to the interplay between the evolving interaction network and turing instability associated with the attitudinal state dynamics.   social dynamics, cultural dissemination, coevolving networks, adaptive networks, social influence, homophily, activator - inhibitor    37n99, 97m70, 91d30
a unified description of single - pion photoproduction data, together with pion- and eta - hadroproduction data, has been achieved in a chew - mandelstam parametrization which is consistent with unitarity at the two - body level.   energy - dependent and single - energy partial wave analyses of pion photoproduction data have been performed and compared to previous said fits and multipoles from the mainz and bonn - gatchina groups.
we propose a concept for production of high power coherent attosecond pulses in x - ray range.   an approach is based on generation of 8th harmonic of radiation in a multistage hghg fel ( high gain high harmonic free electron laser ) configuration starting from shot noise.   single - spike phenomena occurs when electron bunch is passed through the sequence of four relatively short undulators.   the first stage is a conventional `` long '' wavelength ( 0.8 nm ) sase fel which operates in the high - gain linear regime.   the 0.1 nm wavelength range is reached by successive multiplication ( 0.8 nm @xmath0 0.4 nm @xmath0 0.2 nm @xmath0 0.1 nm ) in a stage sequence.   our study shows that the statistical properties of the high - harmonic radiation from the sase fel, operating in linear regime, can be used for selection of radiation pulses with a single spike in time domain.   the duration of the spikes is in attosecond range.   selection of single - spike high - harmonic pulses is achieved by using a special trigger in data acquisition system.   the potential of x - ray sase fel at tesla at desy for generating attosecond pulses is demonstrated. since the design of xfel laboratory at tesla is based on the use of long sase undulators with tunable gap, no special place nor additional fel undulators are required for attophysics experiments.   the use of a 10 gw - level attosecond x - ray pulses at x - ray sase fel facility will enable us to track processes inside atoms.  ,   , and
we discuss the magnetic phases of the hubbard model for the honeycomb lattice both in two and three spatial dimensions.   a ground state phase diagram is obtained depending on the interaction strength @xmath0 and electronic density @xmath1.   we find a first order phase transition between ferromagnetic regions where the spin is maximally polarized ( nagaoka ferromagnetism ) and regions with smaller magnetization ( weak ferromagnetism ).   when taking into account the possibility of spiral states, we find that the lowest critical @xmath0 is obtained for an ordering momentum different from zero. the evolution of the ordering momentum with doping is discussed.   the magnetic excitations ( spin waves ) in the antiferromagnetic insulating phase are calculated from the random - phase - approximation for the spin susceptibility.   we also compute the spin fluctuation correction to the mean field magnetization by virtual emission / absorpion of spin waves. in the large @xmath0 limit  , the renormalized magnetization agrees qualitatively with the holstein - primakoff theory of the heisenberg antiferromagnet, although the latter approach produces a larger renormalization.
we present here a review of the fundamental topics of hartree - fock theory in quantum chemistry. from the molecular hamiltonian, using and discussing the born - oppenheimer approximation, we arrive to the hartree and hartree - fock equations for the electronic problem.   special emphasis is placed in the most relevant mathematical aspects of the theoretical derivation of the final equations, as well as in the results regarding the existence and uniqueness of their solutions.   all hartree - fock versions with different spin restrictions are systematically extracted from the general case, thus providing a unifying framework.   then, the discretization of the one - electron orbitals space is reviewed and the roothaan - hall formalism introduced.   this leads to a exposition of the basic underlying concepts related to the construction and selection of gaussian basis sets, focusing in algorithmic efficiency issues.   finally, we close the review with a section in which the most relevant modern developments ( specially those related to the design of linear - scaling methods ) are commented and linked to the issues discussed.   the whole work is intentionally introductory and rather self - contained, so that it may be useful for non experts that aim to use quantum chemical methods in interdisciplinary applications.   moreover, much material that is found scattered in the literature has been put together here to facilitate comprehension and to serve as a handy reference.    quantum chemistry   ; introduction ; hartree - fock ; basis sets ; scf    * table of contents *    to
we report optical and infrared imaging spectroscopy observations of the young binary object @xmath0  orionis  irs1  a / b.   the brighter component ( @xmath0  ori  irs1  a ) of this binary system has m1 spectral type and a mass in the range of @xmath1  0.3    0.8  @xmath2.   the fainter component ( @xmath0  ori  irs1  b ) has a unique morphology and spectrum.   the unresolved stellar object is surrounded by an extended envelope that is slightly offset from the position of this star.   the envelope s spectrum shows strong emission lines of h and hei but no shock - excited emission from h@xmath3 or .   the embedded stellar object @xmath0  ori  irs1  b has an absorption spectrum characteristic of a late m photosphere, but with an additional approximately equal amount of dust continuum flux veiling the absorption lines.   @xmath0   ori  irs1  b is probably a young brown dwarf embedded in a proplyd that is being photo - evaporated by the uv flux of the nearby multiple o and b star system @xmath0  ori.
i review an extension of the adhmn construction of monopoles to m - brane models.   this extended construction gives a map from solutions to the basu - harvey equation to solutions to the self - dual string equation transgressed to loop space.   loop spaces appear in fact quite naturally in m - brane models.   this is demonstrated by translating a recently proposed m5-brane model to loop space.   finally, i comment on some recent developments related to the loop space approach to m - brane models.   hwm1207 + empg1210
when a driven oscillator loses phase - locking to a master oscillator via a hopf bifurcation, it enters a bounded - phase regime in which its average frequency is still equal to the master frequency, but its phase displays temporal oscillations.   here we characterize these two synchronization regimes in a laser experiment, by measuring the spectrum of the phase fluctuations across the bifurcation.   we find experimentally, and confirm numerically, that the low frequency phase noise of the driven oscillator is strongly suppressed in both regimes in the same way.   thus the long - term phase stability of the master oscillator is transferred to the driven one, even in the absence of phase - locking.   the numerical study of a generic, minimal model suggests that such behavior is universal for any periodically driven oscillator near a hopf bifurcation point.   ocis codes : ( 140.3520 ) lasers, injection - locked ; ( 190.3100 ) instabilities and chaos ; ( 140.3580 ) lasers, solid - state.
the texox-1000 ( toot ) radio source redshift survey is designed to find and study _ typical _ radio - loud active galaxies to high redshift.   they are typical in the same sense that l@xmath0 galaxies are typical of galaxies in the optical.   previous surveys have only included the most luminous, rare objects at and beyond the peak of activity at z@xmath12, but in going a factor of 100 fainter than the 3c survey, and in assembling a large sample, toot probes for the first time the objects that dominate the radio luminosity density of the universe at high redshift. here   we describe the current status of the toot survey and draw preliminary conclusions about the redshift distribution of the radio sources.   so far, @xmath1520 of the 1000 radio sources have redshifts, with @xmath1440 of those in well - defined, complete, sub - regions of the survey. for these   we find a median redshift of z=1, but the measured redshift distribution has a deficit of objects with z@xmath12, when compared to predictions based on extrapolating luminosity functions constrained by higher - flux - density samples.   these are the more luminous objects that usually show emission lines, and which should not be missed in the survey unless they are heavily reddened.   the deficit may be real, but it would not be too surprising to find a population of faint, reddened radio sources at z@xmath12 - 3 among the toot sources yet to have accurate redshifts.   galaxies : active - radio continuum : galaxies - galaxies : surveys : toot
we used the near infrared camera on keck i to obtain @xmath0-band images of four candidate high - redshift radio galaxies selected using optical and radio data in the noao deep wide - field survey in botes.   our targets have 1.4ghz radio flux densities greater than 1mjy, but are undetected in the optical to @xmath1 vega mag. spectral energy distribution fitting suggests that three of these objects are at @xmath2, with radio luminosities near the fr - i / fr - ii break.   the other has photometric redshift @xmath3, but may in fact be at higher redshift.   two of the four objects exhibit diffuse morphologies in @xmath0-band, suggesting that they are still in the process of forming.
we study numerically the dynamics of a one - electron wave packet in a two - dimensional random lattice with long - range correlated diagonal disorder in the presence of a uniform electric field.   the time - dependent schrdinger equation is used for this purpose.   we find that the wave packet displays bloch - like oscillations associated with the appearance of a phase of delocalized states in the strong correlation regime.   the amplitude of oscillations directly reflects the bandwidth of the phase and allows to measure it.   the oscillations reveal two main frequencies whose values are determined by the structure of the underlying potential in the vicinity of the wave packet maximum.
we explicitly derive a complementary pair of four - dimensional _ m_-theory brane - world models, linked by a five - dimensional bulk, each of which has a unique anomaly - free chiral spectrum.   this is done via resolution of local consistency requirements, in the context of the simplest global quotient @xmath0 involving ten - dimensional fixed - planes, for which a chiral four - dimensional spectrum could arise.
we study the correlation between the neutron skin development and the low - energy dipole response associated with the pygmy dipole resonance ( pdr ) in connection with the properties of symmetry energy.   we perform our investigation within a microscopic transport model based on the landau - vlasov kinetic equation by employing three different equations of state in the isovector sector.   together with the giant dipole resonance ( gdr ) for all studied systems, we identify a pdr collective mode whose energy centroid is very well described by the parametrization @xmath0. a linear correlation between the energy weighted sum rule ( ewsr ) associated to pdr and the neutron skin thickness   is evidenced.   an increase of @xmath1 of ewsr, in correspondence to a change of @xmath2 of the neutron skin size, is obtained.   we conjecture that different nuclei having close neutron skin sizes will exhaust the same ewsr in the pygmy region.   this suggests that a precise experimental estimate of the total ewsr exhausted by the pdr allows the determination of the neutron skin size, constraining the slope parameter of the symmetry energy.  ,,,
we study the collective modes of a confined gaseous cloud of bosons and fermions with mutual attractive interactions at zero temperature.   the cloud consists of a bose - einstein condensate and a spin - polarized fermi gas inside a spherical harmonic trap and the coupling between the two species is varied by increasing either the magnitude of the interspecies @xmath0-wave scattering length or the number of bosons.   the mode frequencies are obtained in the collisional regime by solving the equations of generalized hydrodynamics and are compared with the spectra calculated in the collisionless regime within a random - phase approximation.   we find that, as the mixture is driven towards the collapse instability, the frequencies of the modes of fermionic origin show a blue shift which can become very significant for large numbers of bosons.   instead the modes of bosonic origin show a softening, which becomes most pronounced in the very proximity of collapse.   explicit illustrations of these trends are given for the monopolar spectra, but similar trends are found for the dipolar and quadrupolar spectra except for the surface ( @xmath1 ) modes which are essentially unaffected by the interactions.
the kinetic monte carlo method is used to model the dynamic properties of proton diffusion in anhydrous proton conductors.   the results have been discussed with reference to a two - step process called the grotthuss mechanism.   there is a widespread belief that this mechanism is responsible for fast proton mobility.   we showed in detail that the relative frequency of reorientation and diffusion processes is crucial for the conductivity.   moreover, the current dependence on proton concentration has been analyzed. in order to test our microscopic model the proton transport in polymer electrolyte membranes based on benzimidazole c@xmath0h@xmath1n@xmath2 molecules   is studied.
we present a scheme for tuning and controlling nanomechanical resonators by subjecting them to electrostatic gradient fields, provided by nearby tip electrodes.   we show that this approach enables access to a novel regime of optomechanics, where the intrinsic nonlinearity of the nanoresonator can be explored. in this regime,   one or several laser driven cavity modes coupled to the nanoresonator and suitably adjusted gradient fields allow to control the motional state of the nanoresonator at the single phonon level. some applications of this platform have been presented previously @xcite. here, we provide a detailed description of the corresponding setup and its optomechanical coupling mechanisms, together with an in - depth analysis of possible sources of damping or decoherence and a discussion of the readout of the nanoresonator state.
rxj0806.3 + 1527 is suspected to be a double - degenerate white dwarf binary.   we present first results of our nlte analysis of its optical spectrum.   the vlt / fors1 data show a composite spectrum consisting of a blue continuum and superimposed emission lines of the heii pickering series and, possibly, the h balmer series.   our models are based on hot white dwarf atmospheres and include illumination effects onto the secondary star.   the physical parameters and chemical abundances derived from the comparison of the observed spectrum with a grid of model atmospheres provide constraints on the true nature of this enigmatic binary and on the models proposed so far.
the release of plasma in the jovian magnetotail is observed in the form of plasmoids, travelling compression regions, field - aligned particle beams and flux - rope like events.   we demonstrate that electrons propagate along the magnetic field lines in the plasma sheet boundary layer ( psbl ), while close to the current sheet center the electron distribution is isotropic.   the evidences of the counterstreaming electron beams in the psbls are also presented.   most of the field - aligned energetic ion beams are associated with the field - aligned electron beams and about half of them have the bipolar fluctuation of the meridional magnetic field component.   moreover they often show a normal velocity dispersion for the different species which fits well in the scenario of particle propagation from a single source.   all features above are observed during jovian reconfiguration events which are typically bonded with plasma flow reversals. from all these characteristics, which are based on energetic particle measurements  , we believe that the reconfiguration processes in the jovian magnetotail are associated with reconnection.   jupiter, magnetosphere ; magnetic fields ; magnetospheres
we investigate the limitations of length measurements by accelerated observers in minkowski spacetime brought about via the hypothesis of locality, namely, the assumption that an accelerated observer at each instant is equivalent to an otherwise identical momentarily comoving inertial observer.   we find that consistency can be achieved only in a rather limited neighborhood around the observer with linear dimensions that are negligibly small compared to the characteristic acceleration length of the observer.
the article introduces spatial long - range dependent models based on the fractional difference operators associated with the gegenbauer polynomials.   the results on consistency and asymptotic normality of a class of minimum contrast estimators of long - range dependence parameters of the models are obtained. a methodology to verify assumptions for consistency and asymptotic normality of minimum contrast estimators   is developed.   numerical results are presented to confirm the theoretical findings.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
beryllium and oxygen abundances have been derived in a sample of f - type field stars for which lithium abundances had been measured previously, with the aim of obtaining observational constraints to discriminate between the different mixing mechanisms proposed. mixing associated with the transport of angular momentum in the stellar interior and internal gravity waves within the framework of rotating evolutionary models,   appear to be promising ways to explain the observations.
the unique sensitivity of the arecibo telescope at 430 mhz motivated a drift scan search of the visible sky divided up into eight declination strips. based on an analysis of the data collected in the region assigned to us  , eight new long - period pulsars have so far been discovered.    1.25 in.125 in.25 in
the afterglows of gamma - ray bursts ( grbs ) have more soft x - ray absorption than expected from the foreground gas column in the galaxy. while the redshift of the absorption can in general not be constrained from current x - ray observations, it has been assumed that the absorption is due to metals in the host galaxy of the grb.   the large sample of x - ray afterglows and redshifts now available allows the construction of statistically meaningful distributions of the metal column densities.   we construct such a sample and show, as found in previous studies, that the typical absorbing column density ( @xmath0 ) increases substantially with redshift, with few high column density objects found at low to moderate redshifts.   we show, however, that when highly extinguished bursts are included in the sample, using redshifts from their host galaxies, high column density sources are also found at low to moderate redshift.   we infer from individual objects in the sample and from observations of blazars, that the increase in column density with redshift is unlikely to be related to metals in the intergalactic medium or intervening absorbers.   instead we show that the origin of the apparent increase with redshift is primarily due to dust extinction bias : grbs with high x - ray absorption column densities found at @xmath1 typically have very high dust extinction column densities, while those found at the highest redshifts do not.   it is unclear how such a strongly evolving @xmath2 ratio would arise, and based on current data, remains a puzzle.
we seek to develop network algorithms for function computation in sensor networks.   specifically, we want dynamic joint aggregation, routing, and scheduling algorithms that have analytically provable performance benefits due to in - network computation as compared to simple data forwarding. to this end  , we define a class of functions, the fully - multiplexible functions, which includes several functions such as parity, max, and @xmath0-order statistics. for such functions   we characterize the maximum achievable refresh rate of the network in terms of an underlying graph primitive, the min - mincut. in acyclic wireline networks, we show that the maximum refresh rate is achievable by a simple algorithm that is dynamic, distributed, and only dependent on local information. in the case of wireless networks, we provide a maxweight - like algorithm with dynamic flow splitting, which is shown to be throughput - optimal.
we review the results of the 1988 multi - wavelength campaign on the late - type eclipsing binary yy geminorum.   observations include : broad - band optical and near infra - red photometry, simultaneous optical and ultraviolet ( iue ) spectroscopy, x - ray ( ginga ) and radio ( vla ) data. from models fitted to the optical light curves  , fundamental physical parameters have been determined together with evidence for transient maculations ( spots ) located near quadrature longitudes and intermediate latitudes.   eclipses were observed at optical, ultraviolet and radio wavelengths.   significant drops in 6 cm radio emission near the phases of both primary and secondary eclipse indicate relatively compact radio emitting volumes that may lie between the binary components.   iue observations during secondary eclipse are indicative of a uniform chromosphere saturated with mgii plage - type emission and an extended volume of ly@xmath0 emission.   profile fitting of high - dispersion h@xmath0 spectra confirms the chromospheric saturation and indicates significant h@xmath0 opacity to heights of a few percent of the photospheric radius.   there is evidence for an enhanced h@xmath0 emission region visible near phase 0.25 - 0.35 which may be associated with a large spot on the primary and with two small optical flares which were also observed at other wavelengths : one in microwave radiation and the other in x - rays. for both flares,   l@xmath1/l@xmath2 is consistent with energy release in closed magnetic structures.   stars : late - type ; binaries ; eclipsing ; flare ; starspots
the sensitivity of ground - based imaging atmospheric cherenkov @xmath0-ray observatories depends critically on the primary particle identification methods which are used to retain photon - initiated events and suppress the spurious background produced by cosmic rays.   we suggest a new discrimination technique which utilizes differences in the fluctuations of the light intensity in the images of showers initiated by photons and those initiated by protons or heavier nuclei.   the database of simulated events for the proposed veritas observatory has been used to evaluate the efficiency of the new technique.   analysis has been performed for both a single veritas imaging telescope, and a system of these telescopes.   we demonstrate that a discrimination efficiency of @xmath1 can be achieved in addition to traditional background rejection methods based on image shape parameters.   gamma ray astronomy ; cosmic ray background +
the field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy.   there have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. here   we present a simple laboratory experiment to show how planets are detected using the transit technique. following the simple analysis procedure   describe we are able to determine the planetary radius to be @xmath0 which, within errors agrees with the establish value of @xmath1.    accepted for publication in : _ physics education _
we solve for the motion of charged particles in a helical time - periodic abc ( arnold - beltrami - childress ) magnetic field.   the magnetic field lines of a stationary abc field with coefficients @xmath0 are chaotic, and we show that the motion of a charged particle in such a field is also chaotic at late times with positive lyapunov exponent.   we further show that in time - periodic abc fields, the kinetic energy of a charged particle can increase indefinitely with time. at late times   the mean kinetic energy grows as a power law in time with an exponent that approaches unity. for an initial distribution of particles,   whose kinetic energy is uniformly distributed within some interval, the pdf of kinetic energy is, at late times, close to a gaussian but with steeper tails.
assuming that cpt is violated in the neutrino sector seems to be a viable alternative to sterile neutrinos when it comes to reconciling the lsnd anomaly with the remainder of the neutrino data.   there are different ( distinguishable ) ways of incorporating cpt violation into the standard model, including postulating @xmath0. here, i investigate the possibility of introducing cpt violation via lorentz - invariance violating effective operators ( `` ether '' potentials ) which modify neutrino oscillation patterns like ordinary matter effects.   i argue that, within a simplified two - flavor  like oscillation analysis and restricting the analysis to the lowest order lorentz - invariance violating oerators only, one can not solve the solar neutrino puzzle and lsnd anomaly while still respecting constraints imposed by other neutrino experiments, and comment on whether significant improvements should be expected from a three - flavor analysis.   if one turns the picture upside down, some of the most severe constrains on such cpt violating terms can already be obtained from the current neutrino data, while much more severe constraints can arise from future neutrino oscillation experiments.   fermilab - pub-02/060-t +   hep - ph/0204077 +    * can a cpt violating ether solve all electron ( anti)neutrino puzzles? *    andr'e de gouv^ ea    0.5 cm    _ theoretical physics division, fermilab + p.o. box 500, batavia, il 60510, usa _
we review recent progress in understanding black hole structure and dynamics via matrix theory.   talk by the second author, presented at strings 97 ( amsterdam, june 16 - 20, 1997 ).   # 1( )    # 1#1 # 1#2#1#2 # 1#2    # 1#1| # 1| # 1 # 1#1   = 11 /#1 a # 1#2  = 12 # 1
i discuss why photon production from the quark gluon plasma ( qgp ) presents an interesting problem, both experimentally and theoretically.   i show how the photon emission rate can be computed under the simplifying assumption that the qgp fully thermalizes.   the theoretical issues are very similar to those for jet energy loss ; so it should be possible to treat them in a common formalism and relate the predictions of one phenomenon to those of the other.
the energy sources of nine infrared luminous galaxies ( irlgs ) are diagnosed based on their ground - based 34 @xmath0 m spectra.   both the equivalent width of the 3.3 @xmath0 m polycyclic aromatic hydrocarbon ( pah ) emission feature and the 3.3 @xmath0 m pah to far - infrared luminosity ratio ( @xmath1/@xmath2 ) are analyzed.   assuming nuclear compact starburst activity in these sources produces the 3.3 @xmath0 m pah emission as strongly as that in starburst galaxies with lower far - infrared luminosities, the followings results are found : for six irlgs, both the observed equivalent widths and the @xmath1/@xmath2 ratios are too small to explain the bulk of their far - infrared luminosities by compact starburst activity, indicating that active galactic nucleus ( agn ) activity is a dominant energy source.   for the other three irlgs, while the 3.3 @xmath0 m pah equivalent widths are within the range of starburst galaxies, the @xmath1/@xmath2 ratios after correction for screen dust extinction are a factor of @xmath33 smaller. the uncertainty in the dust extinction correction factor and in the scatter of the intrinsic @xmath1/@xmath2 ratios for   starburst galaxies do not allow a determination of the ultimate energy sources for these three irlgs.
if cluster dark matter is in the form of compact objects it will introduce fluctuations into the light curves of distant sources.   current searches for machos in clusters of galaxies focus on monitoring quasars behind nearby systems.   this paper considers the effect of such a compact population on the surface brightness distribution of giant gravitationally lensed arcs. as   the microlensing optical depth is significant in these clusters, the expected fluctuations are substantial and are observable. focusing on the giant arc seen in abell 370,   we demonstrate that several ` extreme'events would be visible in a comparison of hst observations at two epochs. utilizing ngst,   long term monitoring should reveal a ubiquitous twinkling of brightness over the surface of the arcs.
various approaches of defining and determining work performed on a quantum system are compared.   any operational definition of work, however, must allow for two facts, first, that work characterizes a process rather than an instantaneous state of a system, and, second, that quantum systems are sensitive to the interactions with a measurement apparatus.   we compare different measurement scenarios on the basis of the resulting post - measurement states and the according probabilities for finding a particular work value.   in particular, we analyze a recently proposed work - meter for the case of a gaussian pointer state and compare it with the results obtained by two projective and, alternatively, two gaussian measurements. in the limit of a strong effective measurement strength the work distribution of projective two energy measurements can be recovered. in the opposite limit   the average of work becomes independent of any measurement.   yet the fluctuations about this value diverge.   the performance of the work - meter is illustrated by the example of a spin in a suddenly changing magnetic field.
we present a numerical method for studying the normal modes of accretion flows around black holes. in this first paper  , we focus on two - dimensional, viscous, hydrodynamic disks, for which the linear modes have been calculated analytically in previous investigations.   we use pseudo - spectral methods and low storage runge - kutta methods to solve the continuity equation, the navier - stokes equation, and the energy equation.   we devise a number of test problems to verify the implementation.   these tests demonstrate the ability of spectral methods to handle accurately advection problems and to reproduce correctly the stability criteria for differentially rotating hydrodynamic flows.   they also show that our implementation is able to handle sound wave correctly with non - reflective boundary conditions, to recover the standard solution for a viscous spreading ring, and produce correctly the shakura - sunyaev steady disk solution.   finally, we have applied our algorithm to the problem of a non - axisymmetric viscous spreading ring and verify that such configuration is unstable to non - antisymmetric perturbations.
experimental evidence suggests that the fulde - ferrell - larkin - ovchinnikov ( fflo ) state may be realized in the unconventional, heavy - fermion superconductor cecoin@xmath0.   we present a self - consistent calculation of the field versus temperature phase diagram and order parameter structures for the fflo states of quasi - two - dimensional @xmath1-wave superconductors.   we calculate the spatially nonuniform order parameter, free energy density, and local density of states for magnetic fields parallel to the superconducting planes.   we predict that the lower critical magnetic field transition between the spatially uniform and nonuniform fflo state is second order.   we discuss the signatures of the nonuniform fflo state which should be observable in scanning tunneling microscopy measurements of the local density of states.
we reinvestigate the infrared behavior of the pressure in the @xmath0 scalar theory in six dimensions.   this problem was first studied by almeida and frenkel and more recently by carrington et al.  , that certified their results under certain approximations.   we employ an alternative technique, instead of the approximation methods necessary to truncate the schwinger - dyson equations, often considered to calculate the pressure nonperturbatively.   a daisy - type sum, implemented through the modified self - consistent resummation ( mscr ), is enough to take care of the infrared divergences ensuring the finiteness of the pressure.   pacs numbers : @xmath1
a survey probing respondents views on various foundational issues in quantum mechanics was recently created by schlosshauer, kofler, and zeilinger and then given to 33 participants at a quantum foundations conference. here   we report the results of giving this same survey to the attendees at another recent quantum foundations conference.   while it is rather difficult to conclude anything of scientific significance from the poll, the results do strongly suggest several interesting cultural facts  for example, that there exist, within the broad field of `` quantum foundations '', sub - communities with quite different views, and that ( relatedly ) there is probably even significantly more controversy about several fundamental issues than the already - significant amount revealed in the earlier poll.
nous tudions dans ce texte lapproximation diophantienne et la distribution locale en un point rationnel sur une surface torique obtenue comme un clatement de @xmath0. il savre quen dehors dun ferm de zariski les meilleures approximations sobtiennent  laide dune famille de courbes nodales.   ltude se ramne donc  la question de la distribution locale en un point quadratique sur la droite projective.
we revisit the glauber model to study the heavy ion reaction cross sections and elastic scattering angular distributions at low and intermediate energies.   the glauber model takes nucleon - nucleon cross sections and nuclear densities as inputs and has no free parameter and thus can predict the cross sections for unknown systems.   the glauber model works at low energies down to coulomb barrier with very simple modifications.   we present new parametrization of measured total cross sections as well as ratio of real to imaginary parts of the scattering amplitudes for pp and np collisions as a function of nucleon kinetic energy. the nuclear ( charge )   densities obtained by electron scattering form factors measured in large momentum transfer range are used in the calculations.   the heavy ion reaction cross sections are calculated for light and heavy systems and are compared with available data measured over large energy range.   the model gives excellent description of the data.   the elastic scattering angular distributions are calculated for various systems at different energies.   the model gives good description of the data at small momentum transfer but the calculations deviate from the data at large momentum transfer.   glauber model, heavy ion reaction cross section, elastic scattering
we apply the schrdinger functional method to the abelian gauge theory in three dimensions with @xmath0 four - component fermions.   we find that the calculated beta function does not cross zero in the range of coupling we study.   this implies that the theory exhibits confinement and mass generation, rather than a conformal infared regime.
microlensing surveys search for the transient brightening of a background star that is the signature of gravitational lensing by a foreground compact object.   this technique is an elegant way to search for astrophysical candidates that might comprise the dark matter halo of the milky way.   while the current projects have successfully detected the phenomenon of microlensing and have reported many important results, the relatively large event rate reported towards the lmc remains a puzzle.   the first step in resolving this mystery is determining the _ location _ of the excess lensing population.   this will require a microlensing survey with an order of magnitude increase in sensitivity over current projects.   i summarize the present status of microlensing surveys, and present ( and advocate! ) a next - generation program that should be capable of unambiguously determining whether the dark halo of the galaxy is indeed made up of machos, or whether the observed events are due to previously unappreciated ordinary stellar populations.   # 110^#1 versim#1#20.2ex # 1@xmath0 # 1@xmath1 # 1#1 # 1v_#1(halo ) # 1v_#1(disk ) # 1v_#1(tot )
we examine the time - reversal - violating nuclear `` schiff moment '' that induces electric dipole moments in atoms. after presenting a self - contained derivation of the form of the schiff operator,   we show that the distribution of schiff strength, an important ingredient in the ground - state schiff moment, is very different from the electric - dipole - strength distribution, with the schiff moment receiving no strength from the giant dipole resonance in the goldhaber - teller model.   we then present shell - model calculations in light nuclei that confirm the negligible role of the dipole resonance and show the schiff strength to be strongly correlated with low - lying octupole strength.   next, we turn to heavy nuclei, examining recent arguments for the strong enhancement of schiff moments in octupole - deformed nuclei over that of @xmath0hg, for example.   we concur that there is a significant enhancement while pointing to effects neglected in previous work ( both in the octupole - deformed nuclides and @xmath0hg ) that may reduce it somewhat, and emphasizing the need for microscopic calculations to resolve the issue.   finally, we show that static octupole deformation is not essential for the development of collective schiff moments ; nuclei with strong octupole vibrations have them as well, and some could be exploited by experiment.
in this paper, we investigate joint relay and jammer selection in two - way cooperative networks, consisting of two sources, a number of intermediate nodes, and one eavesdropper, with the constraints of physical layer security. specifically, the proposed algorithms select two or three intermediate nodes to enhance security against the malicious eavesdropper.   the first selected node operates in the conventional relay mode and assists the sources to deliver their data to the corresponding destinations using an amplify - and - forward protocol.   the second and third nodes are used in different communication phases as jammers in order to create intentional interference upon the eavesdropper node.   firstly, we find that in a topology where the intermediate nodes are randomly and sparsely distributed, the proposed schemes with cooperative jamming outperform the conventional non - jamming schemes within a certain transmitted power regime.   we also find that, in the scenario in which the intermediate nodes gather as a close cluster, the jamming schemes may be less effective than their non - jamming counterparts.   therefore, we introduce a hybrid scheme to switch between jamming and non - jamming modes.   simulation results validate our theoretical analysis and show that the hybrid switching scheme further improves the secrecy rate.
we report on the analysis of a large sample of 744 type 1 active galactic nuclei, including quasars and seyfert1 galaxies across the redshift range from @xmath0 and spanning nearly 6 orders of magnitude in continuum luminosity.   we discuss correlations of continuum and emission line properties in the rest - frame ultraviolet and optical spectral ranges.   the well established baldwin effect is detected for almost all emission lines from ovi@xmath1 to @xmath2.   their equivalent widths are significantly anti - correlated with the continuum strength, while they are nearly independent of redshift.   this is the well known baldwin effect.   its slope @xmath3, measured as log@xmath4, shows a tendency to become steeper towards higher luminosity.   the slope of the baldwin effect also increases with the ionization energy needed to create the individual lines.   in contrast to this general trend, the nv@xmath5 equivalent width is nearly independent of continuum luminosity and remains nearly constant.   the overall line behaviors are consistent with softer uv continuum shapes and perhaps increasing gas metallicity in more luminous active galactic nuclei.
the recent discovery of super - earths ( masses @xmath0 10 @xmath1 ) has initiated a discussion about conditions for habitable worlds. among these   is the mode of convection, which influences a planet s thermal evolution and surface conditions. on earth, plate tectonics has been proposed as a necessary condition for life. here   we show, that super - earths will also have plate tectonics.   we demonstrate that as planetary mass increases, the shear stress available to overcome resistance to plate motion increases while the plate thickness decreases, thereby enhancing plate weakness.   these effects contribute favorably to the subduction of the lithosphere, an essential component of plate tectonics.   moreover, uncertainties in achieving plate tectonics in the one earth - mass regime disappear as mass increases : super - earths, even if dry, will exhibit plate tectonic behaviour.
prevalence of cooperation within groups of selfish individuals is puzzling in that it contradicts with the basic premise of natural selection. favoring players with higher fitness,   the latter is key for understanding the challenges faced by cooperators when competing with defectors.   evolutionary game theory provides a competent theoretical framework for addressing the subtleties of cooperation in such situations, which are known as social dilemmas.   recent advances point towards the fact that the evolution of strategies alone may be insufficient to fully exploit the benefits offered by cooperative behavior. indeed,   while spatial structure and heterogeneity, for example, have been recognized as potent promoters of cooperation, coevolutionary rules can extend the potentials of such entities further, and even more importantly, lead to the understanding of their emergence.   the introduction of coevolutionary rules to evolutionary games implies, that besides the evolution of strategies, another property may simultaneously be subject to evolution as well.   coevolutionary rules may affect the interaction network, the reproduction capability of players, their reputation, mobility or age. here   we review recent works on evolutionary games incorporating coevolutionary rules, as well as give a didactic description of potential pitfalls and misconceptions associated with the subject.   in addition, we briefly outline directions for future research that we feel are promising, thereby particularly focusing on dynamical effects of coevolutionary rules on the evolution of cooperation, which are still widely open to research and thus hold promise of exciting new discoveries.    evolutionary games, coevolution, social dilemmas, cooperation 02.50.le, 87.23.ge, 87.23.kg, 89.75.fb
if dark matter decays to electromagnetically - interacting particles, it can inject energy into the baryonic gas and thus affect the processes of recombination and reionization.   this leaves an imprint on the cosmic microwave background ( cmb ) : the large - scale polarization is enhanced, and the small - scale temperature fluctuation is damped.   we use the wmap three - year data combined with galaxy surveys to constrain radiatively decaying dark matter.   our new limits to the dark - matter decay width are about ten times stronger than previous limits. for dark - matter lifetimes that exceed the age of the universe,   a limit of @xmath0 ( 95% cl ) is derived, where @xmath1 is the efficiency of converting decay energy into ionization energy.   limits for lifetimes short compared with the age of the universe are also derived.   we forecast improvements expected from the planck satellite.
oxygen vacancies at the sno@xmath0 and @xmath1 surface and subsurface sites have been studied in the framework of density functional theory by using both all - electron gaussian and pseudopotential plane - wave methods.   the all - electron calculations have been performed using the b3lyp exchange - correlation functional with accurate estimations of energy gaps and density of states.   we show that bulk oxygen vacancies are responsible for the appearance of a fully occupied flat energy level lying at about 1 ev above the top valence band, and an empty level resonant with the conduction band.   surface oxygen vacancies strongly modify the surface band structures with the appearance of intragap states covering most of the forbidden energy window, or only a small part of it, depending on the vacancy depth from the surface.   oxygen vacancies can account for electron affinity variations with respect to the stoichiometric surfaces as well. a significant support to the present results is found by comparing them to the available experimental data.
we show that charged vector mesons can not be condensed by a magnetic field. although some hadron models predict the charged vector meson condensation in a strong magnetic field, we prove, by means of the vafa - witten theorem, that this is not the case in qcd.   we also perform the numerical analysis for the meson mass and condensation in lattice qcd.   the lattice qcd data confirm no charged vector meson condensation in a magnetic field.
if a magnetic field normal to the surface of a magnetic fluid is increased beyond a critical value a spontaneous deformation of the surface arises ( normal field instability ).   the instability is subcritical and leads to peaks of a characteristic shape.   we investigate the neighborhood of this instability experimentally under the influence of a temporal modulation of the magnetic field.   we use a small vessel, where only one peak arises.   the modulation can either be stabilizing or destabilizing, depending on the frequency and amplitude.   we observe a cascade of odd - numbered response - periods up to period 11, and also a domain of even - numbered periods.   we propose a minimal model involving a cutoff - condition which captures the essence of the experimental observations.   pacs : 47.20.-k, 47.20.ky, 75.50.mm + keywords : magnetic fluid ; nonlinear oscillator ; subharmonic response ; surface instability ;
the light deflection of one component of a binary system due to the gravitational field of the other component is investigated. while this relativistic effect has not been observed thus far  , the question arises that whether this effect becomes detectable in view of todays high - precision astrometry which soon will reach the microarcsecond level of accuracy.   the effect is studied and its observability is investigated.   it turns out, that in total there are about @xmath0 binaries having orbital parameters such that the light deflection amounts to be at least @xmath1 microarcsecond.   two stringent criteria for the orbital parameters are presented, by means of which one can easily determine the maximal value of light deflection effect for a given binary system.   it is found, that for relevant binaries their orbital parameters must take rather extreme values in order to have a light deflection of the order of a few microarcseconds. only in a very few and rather extreme binary systems the light deflection effect might be detectable by todays astrometry, but their existence is highly improbable.   thus, the detection of this subtle effect of relativity still remains a challenge for future astrometric missions.
recently, research that focuses on the rigorous understanding of the relation between simulation and/or exact models on graphs and approximate counterparts has gained lots of momentum.   this includes revisiting the performance of classic pairwise models with closures at the level of pairs and/or triples as well as effective - degree - type models and those based on the probability generating function formalism. in this paper, for a fully connected graph and the simple @xmath0 ( susceptible - infected - susceptible ) epidemic model, a novel closure is introduced.   this is done via using the equations for the moments of the distribution describing the number of infecteds at all times combined with the empirical observations that this is well described / approximated by a binomial distribution with time dependent parameters.   this assumption allows us to express higher order moments in terms of lower order ones and this leads to a new closure.   the significant feature of the new closure is that the difference of the exact system, given by the kolmogorov equations, from the solution of the newly defined approximate system is of order @xmath1.   this is in contrast with the @xmath2 difference corresponding to the approximate system obtained via the classic triple closure.   +    @xmath3 school of mathematical and physical sciences, department of mathematics, university of sussex, falmer, brighton bn1 9qh, uk + @xmath4 institute of mathematics, etvs lornd university budapest, budapest, hungary +    @xmath5 corresponding author + email : i.z.kiss@sussex.ac.uk +    * keywords : * markov chain ; epidemic ; pairwise model ; pairwise closure
recent theoretical and observational progress has substantially improved the definition of the lower main sequence and established a new basis for a comparison of main sequence stars and the secondaries in cvs.   the evolutionary sequences of kolb & baraffe  imply that the secondaries in many cvs are expanded compared with main sequence stars of the same mass as a consequence of unusually high mass transfer rates and/or pre - cv nuclear evolution.   we show that the location of the secondaries of all well - studied cvs in the spectral type period diagram implies that they are consistent with having near - solar metallicities.   we show, furthermore, that the surface brightness of k / m stars depends on gravity and metallicity and present new barnes - evans relations valid for dwarfs of near - solar metallicity and the secondaries in cvs of the galactic disk population.   distances derived by the surface brightness method agree with recent measurements of the trigonometric parallaxes of a few selected systems.
in this paper we present an empirical study of the worldwide maritime transportation network ( wmn ) in which the nodes are ports and links are container liners connecting the ports. using the different representations of network topology namely the space @xmath0 and @xmath1, we study the statistical properties of wmn including degree distribution, degree correlations, weight distribution, strength distribution, average shortest path length, line length distribution and centrality measures.   we find that wmn is a small - world network with power law behavior.   important nodes are identified based on different centrality measures. through analyzing weighted cluster coefficient and weighted average nearest neighbors degree  , we reveal the hierarchy structure and rich - club phenomenon in the network.
wireless sensor networks are appearing as an emerging need for mankind.   though, such networks are still in research phase however, they have high potential to be applied in almost every field of life.   lots of research is done and a lot more is awaiting to be standardized. in this work, cluster based routing in wireless sensor networks is studied precisely.   further, we modify one of the most prominent wireless sensor network s routing protocol `` leach '' as modified leach ( modleach ) by introducing _   efficient cluster head replacement scheme _ and _ dual transmitting power levels_. our modified leach, in comparison with leach out performs it using metrics of cluster head formation, through put and network life.   afterwards, hard and soft thresholds are implemented on modified leach ( modleach ) that boast the performance even more.   finally a brief performance analysis of leach, modified leach ( modleach ), modleach with hard threshold ( modleachht ) and modleach with soft threshold ( modleachst ) is undertaken considering metrics of throughput, network life and cluster head replacements.   leach, wireless, sensor, networks, routing, protocol, modleach, wsn s, cluster, head, threshold
we propose a new method to analyse the alignment of optical polarisation vectors from quasars.   this method leads to a definition of intrinsic preferred axes and to a determination of the probability @xmath0 that the distribution of polarisation directions is random.   this probability is found to be as low as @xmath1 for one of the regions of redshift.
it is of great interest whether the recent kamland bound on the flux of electron antineutrinos from the sun constrains the electromagnetic properties of the neutrino.   we examine the efficiency of the electron antineutrino production in the solar magnetic fields, assuming the neutrinos are majorana particles with a relatively large transition moment.   we consider fields both in the radiative and convective zones of the sun, with physically plausible strengths, and take into account the recently established values of the oscillation parameters.   our analysis shows that the production rate in question is presently unobservable. in the radiative zone,   it is suppressed by the large measured value of the flavor mixing angle which eliminates the resonant level crossing.   a corresponding general resonance condition, valid for large as well as small values of the mixing angle, is derived.   likewise, in the convective zone, the strength of the small - scale magnetic field is likely to be insufficient.   thus, no useful bound on the neutrino transition moment can be derived from the published kamland bound.   kamland may be, however, on the edge of probing an `` optimistic '' scenario, making further improvements of its sensitivity desirable.
we give an overview of the current theory of collective modes in trapped atomic gases at finite temperatures, when the dynamics of the condensate and non - condensate must both be considered.   a simple introduction is given to the quantum field formulation of the dynamics of an interacting bose - condensed system, based on equations of motion for the condensate wavefunction and single - particle green s functions for the non - condensate atoms.   we discuss the nature of excitations in the mean - field collisionless region, including the beliaev second - order approximation for the self - energies.   we also sketch the derivation of coupled two - fluid hydrodynamic equations using a simple kinetic equation which includes collisions between condensate and non - condensate atoms.
the discovery of new wolf - rayet ( wr ) stars in our galaxy via large - scale narrowband optical surveys has been severely limited by dust extinction.   recent improvements in infrared technology have made narrowband - broadband imaging surveys viable again.   we report a new j, k and narrow - band imaging survey of 300 square degrees of the plane of the galaxy, spanning 150 degrees in galactic longitude and reaching 1 degree above and below the galactic plane.   the survey has a useful limiting magnitude of k = 15 over most of the observed galactic plane, and k = 14 within a few degrees of the galactic center.   thousands of emission line candidates have been detected. in spectrographic follow - ups of 173 wr star candidates   we have discovered 41 new wr stars, 15 of type wn and 26 of type wc.   star subtype assignments have been confirmed with k band spectra, and distances approximated using the method of spectroscopic parallax.   a few of the new wr stars are amongst the most distant known in our galaxy.   the distribution of these new wr stars is seen to follow that of previously known wr stars along the spiral arms of the galaxy.   tentative radial velocities were also measured for most of the new wr stars.
a scheme to reduce translational noninvariant quasi - one - dimensional wave guides into singly or multiply connected one - dimensional ( 1d ) lines is proposed.   it is meant to simplify the analysis of wave guides, with the low - energy properties of the guides preserved.   guides comprising uniform - cross - sectional sections and discontinuities such as bends and branching junctions are considered.   the uniform sections are treated as 1d lines, and the discontinuities are described by equations sets connecting the wave functions on the lines. the procedures to derive the equations and to solve reduced systems are illustrated by examples, and the scheme is found to apply when the discontinuities are distant and   the energy is low.   when the scheme applies, it may substantially simplify the analysis of a wave guide, and hence the scheme may find uses in the study of related problems, such as quantum wire networks.   wave guide, discontinuity, quantum wire, one - dimensional,    43.20.mv,73.23.ad,73.63.nm,84.40.az
_ orfeus _ far uv echelle spectra have been used to investigate hi, h@xmath0 and co absorption lines along the line of sight towards lh 10:3120 in the lmc, extending the study presented by deboer et al.   ( 1998 ). while h@xmath0 absorption is clearly visible,   no co absorption at lmc velocities is detected, but an upper limit of @xmath1co@xmath2 @xmath3 for the co column density is derived for the c - x band near 1088 .   the detected h@xmath0 absorption features were used to determine a limit for the h@xmath0/co ratio of @xmath4(h@xmath0)/@xmath4(@xmath5co ) @xmath6 for the lmc gas along this individual line of sight. generally, the fraction of gas in molecular form in the lmc is low compared to interstellar gas in the milky way with the same total gas quantity.   we compare the absorption spectroscopy with _ sest _   co emission line measurements.   it is found that most of the co emission comes from gas behind lh 10:3120.   we discuss our results in view of the possible scenario, in which the low dust content limits the amount of molecular hydrogen in the diffuse lmc gas.
we study the dynamics of single photonic and atomic excitations in the jaynes - cummings - hubbard ( jch ) model where the cavities are arranged in an apollonian network ( an ). the existence of a gapped field normal frequency spectrum along with strongly localized eigenstates on the an highlights many of the features provided by the model. by numerically diagonalizing the jch hamiltonian in the single excitation subspace  , we evaluate the time evolution of fully localized initial states, for many energy regimes.   we provide a detailed description of the photonic quantum walk on the an and also address how an effective jaynes - cummings interaction can be achieved at the strong hopping regime. when the hopping rate and the atom - field coupling strength is of the same order, the excitation is relatively allowed to roam between atomic and photonic degrees of freedom as it propagates.   however, different cavities will contribute mostly to one of these components, depending on the detuning and initial conditions, in contrast to the strong atom - field coupling regime, where atomic and photonic modes propagate identically.   pacs numbers : :    42.50.pq, 42.50.ex, 03.67.-a, 89.75.da
the realization that the total energy of grbs is correlated with their jet break angles motivates the search for a similar relation between the peak luminosity, @xmath0, and the jet break angles, @xmath1.   such a relation implies that the grb luminosity function determines the angular distribution.   we re - derive the grb luminosity function using the batse peak flux distribution and compare the predicted distribution with the observed redshift distribution.   the luminosity function can be approximated by a broken power law with a break peak luminosity of @xmath2 erg / sec, a typical jet angle of 0.12 rad and a local grb rate of @xmath3  gpc@xmath4yr@xmath5.   the angular distribution implied by @xmath1 agrees well with the observed one, and implies a correction factor to the local rate due to beaming of @xmath6 ( instead of 500 as commonly used ).   the inferred overall local grb rate is @xmath7  gpc@xmath4yr@xmath5.   the luminosity function and angle distribution obtained within the universal structured jet model, where the angular distribution is essentially @xmath8 and hence the luminosity function must be @xmath9, deviate from the observations at low peak fluxes and, correspondingly, at large angles. the corresponding correction factor for the universal structure jet is @xmath10.
the european vlbi network ( evn ) has been used at two epochs in 2003 and 2009 to obtain multi - frequency high - resolution images of the merger galaxy ngc6240 in order to study the radio properties of all compact high - brightness components in the galaxy.   our observations at milli - arcsecond resolution detected the northern and southern nuclei and two radio components, which we interpret as long - lived luminous supernovae associated with the circum - nuclear starburst activity at the southern nucleus.   the new vlbi data support the presence of an active galactic nucleus ( agn ) together with starburst activity at the southern nucleus and provides some evidence for an agn at the northern nucleus.   the two nuclei both display an inverted spectrum at lower ghz frequencies.   the spectrum of the southern nucleus indicates thermal free - free absorption on parsec scales, consistent with the presence of an agn.
one common feature of a vehicle, an ant and a kinesin motor is that they all convert chemical energy, derived from fuel or food, into mechanical energy required for their forward movement ; such objects have been modelled in recent years as _ self - driven _   `` particles ''.   cytoskeletal filaments, e.g., microtubules, form a `` rail '' network for intra - cellular transport of vesicular cargo by molecular motors like, for example, kinesins.   similarly, ants move along trails while vehicles move along lanes.   therefore, the traffic of vehicles and organisms as well as that of molecular motors can be modelled as systems of interacting self - driven particles ; these are of current interest in non - equilibrium statistical mechanics. in this paper   we point out the common features of these model systems and emphasize the crucial differences in their physical properties.
the ground - state phases of a spin - orbit ( so ) coupled atomic spin-2 bose - einstein condensate ( bec ) are studied.   interesting density patterns spontaneously formed are widespread due to the competition between so coupling and spin - dependent interactions like in a so coupled spin-1 condensate. unlike the case of spin-1 condensates, which are characterized by either ferromagnetic or polar phase in the absence of so  , spin-2 condensates can take a cyclic phase, where we find the patterns formed due to so are square or triangular in their spin component densities for axial symmetric so interaction.   both patterns are found to continuously evolve into striped forms with increased asymmetry of the so coupling.
we investigate here gravitational collapse of a perfect fluid with a linear isentropic equation of state @xmath0. a class of collapse models is given which is a family of solutions to einstein equations and the final fate of collapse is analyzed in terms of the formation of black holes and naked singularities.   the collapse evolves from a regular initial data and the positivity of energy conditions and other physical regularity conditions are satisfied. as we provided here an explicit class, this gives useful insights into the endstates of collapse with a physically reasonable and relevant equation of state and for the cosmic censorship hypothesis.
we present a light curve model for the super - eddington luminosity phase of five classical novae observed with _   iue_. optical and uv light curves are calculated based on the optically thick wind theory with a reduced effective opacity for a porous atmosphere.   fitting a model light curve with the uv 1455    light curve, we determine the white dwarf mass and distance to be @xmath0, 4.4 kpc ) for, @xmath1, 1.8 kpc ) for, @xmath2, 4.1 kpc ) for, @xmath3, 2.1 kpc ) for, and @xmath3, 4.3 kpc ) for.
we contrast the impact of higgs mediated flavor changing neutral currents on @xmath0 in the framework of a warped extra dimension that was recently calculated by azatov et al.  with the older results for kaluza - klein   gluon induced corrections to that observable.   we find that the most stringent constraint on the kk scale for a higgs field localized on the infrared brane for reasonable additional assumptions comes from kk gluon exchange. in the case of a bulk higgs field   we show that for certain scenarios the higgs contribution can in fact exceed the kk gluon contribution.   in the course of this analysis we also describe in detail the different renormalization procedures that have to be employed in the kk gluon and higgs cases to relate the new physics at high energies to low energy observables.   tum - hep-745/09    * bjoern duling@xmath1 *     @xmath1_physik department, technische universitt mnchen, d-85748 garching, germany _
we present an investigation of the scale - dependence of bias described by the linear model : @xmath0, @xmath1 being the bias parameter, and @xmath2 and @xmath3 are the galaxy number density and mass density, respectively. using a discrete wavelet decomposition,   we show that the behavior of bias scale - dependence can not be described by one parameter @xmath1. in the linear bias model   the scale - dependence should be measured by the @xmath4-spectra of wavelet - coefficient - represented bias parameters @xmath5 and @xmath6, @xmath7 being positive integers.   because @xmath5 with different @xmath7 are independent from each other, a systematic analysis of the @xmath4-spectra of @xmath5 and @xmath6 is necessary.   we performed a @xmath4-spectrum analysis for samples of elliptical and lenticular ( el ), and spiral ( sp ) galaxies listed in the apm bright galaxy catalog.   we found that, for statistics of two - point correlation functions or dwt power spectrum, the scale - independence holds within 1 @xmath8.   however, the bias scale - dependence becomes substantial when phase - sensitive statistics ( e.g. @xmath5 with @xmath9 or @xmath6 ) are applied.   these results indicate that the bias scale - dependence has the same origin as the non - gaussianity of galaxy distributions.   this is generally consistent with the explanation that the bias scale - dependence originated from non - linear and non - local relationship between galaxy formation and their environment.
we study the statistical mechanics of a general hamiltonian system in the context of symplectic structure of the corresponding phase space.   this covariant formalism reveals some interesting correspondences between properties of the phase space and the associated statistical physics.   while topology, as a global property, turns out to be related to the total number of microstates, the invariant measure which assigns _ a priori _ probability distribution over the microstates, is determined by the local form of the symplectic structure. as an example of a model for which the phase space has a nontrivial topology, we apply our formulation on the snyder noncommutative space - time with de sitter four - momentum space and analyze the results.   finally, in the framework of such a setup, we examine our formalism by studying the thermodynamical properties of a harmonic oscillator system.   pacs numbers : :    05.20.-y ; 02.40.-k ; 02.40.gh key words : :    statistical mechanics, noncommutative geometry, symplectic geometry
we study the phase space available to the local stellar distribution using a galactic potential consistent with several recent observational constraints.   we find that the induced phase space structure has several observable consequences.   the spiral arm contribution to the kinematic structure in the solar neighborhood may be as important as the one produced by the galactic bar.   we suggest that some of the stellar kinematic groups in the solar neighborhood, like the hercules structure and the kinematic branches, can be created by the dynamical resonances of self - gravitating spiral arms and not exclusively by the galactic bar.   a structure coincident with the arcturus kinematic group is developed when a hot stellar disk population is considered, which introduces a new perspective on the interpretation of its extragalactic origin.   a bar - related resonant mechanism can modify this kinematic structure.   we show that particles in the dark matter disk - like structure predicted by recent lcdm galaxy formation experiments, with similar kinematics to the thick disk, are affected by the same resonances, developing phase space structures or dark kinematic groups that are independent of the galaxy assembly history and substructure abundance.   we discuss the possibility of using the stellar phase space groups as constraints to non - axisymmetric models of the milky way structure.
following recent work by lambiase and nesterenko we study in detail the interquark potential for a nambu - goto string with point masses attached to its ends.   we obtain exact solutions to the gap equations for the lagrange multipliers and metric components and determine the potential without simplifying assumptions.   we also discuss lscher term and argue that it remains universal.
entangling and disentangling capacities are the key manifestation of the nonlocal content of a quantum operation.   a lot of effort has been put recently into investigating ( dis)entangling capacities of unitary operations, but very little is known about capacities of non - unitary operations. here   we investigate ( dis)entangling capacities of unital cptp maps acting on two qubits.
relativistic jets carry a significant fraction of the total energy budget of a radio source, rivaling the power that is extracted through accretion.   a minor part of this bulk kinetic power is transformed to radiation, possibly through internal shocks if the plasma is accelerated, at the base of the jet, to a velocity which changes in time. in this way   we can understand why some radiation is produced all along the jet even if most of it originates at a preferred location, and why the efficiency of conversion of bulk to random energy is small.   the recent observations by chandra of intense jet x  ray emission at large scales suggest that at least the  spine " of jets continues to be highly relativistics even up to hundreds of kiloparsecs away from the nucleus and give tight lower limits on the jet bulk kinetic power.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study the properties of soliton solutions in an analog of the skyrme model in 2 + 1 dimensions whose lagrangian contains the skyrme term and the mass term, but no usual kinetic term.   the model admits a symmetry under area preserving diffeomorphisms.   we solve the dynamical equations of motion analytically for the case of spinning isolated baryon type solitons.   we take fully into account the induced deformation of the spinning skyrmions and the consequent modification of its moment of inertia to give an analytical example of related numerical behaviour found by piette _   et al. _   @xcite.   we solve the equations of motion also for the case of an infinite, open string, and a closed annular string. in each case, the solitons are of finite extent, so called  compactons ", being exactly the vacuum outside a compact region.   we end with indications on the scattering of baby - skyrmions, as well as some considerations as the properties of solitons on a curved space.   .5truecm
although it is now understood that chaos in complex classical systems is the foundation of thermodynamic behavior, the detailed relations between the microscopic properties of the chaotic dynamics and the macroscopic thermodynamic observations still remain mostly in the dark. in this work,   we numerically analyze the probability of chaos in strongly nonlinear hamiltonian systems and find different scaling properties depending on the nonlinear structure of the model.   we argue that these different scaling laws of chaos have definite consequences for the macroscopic diffusive behavior, as chaos is the microscopic mechanism of diffusion.   this is compared with previous results on chaotic diffusion [ new j.  phys.   15, 053015 ( 2013 ) ], and a relation between microscopic chaos and macroscopic diffusion is established.    *   the relation of the properties of microscopic chaos with the macroscopic phenomenon of diffusion has been studied since chirikov s early works in the late 70s  @xcite.   recently, subdiffusive spreading in disordered nonlinear systems was found and studied extensively.   analyzing the chaotic behavior as the origin of this subdiffusive process will give further insight in the properties of the spreading and will help to explain some controversially discussed observations.   quantifying the probability of chaos in such systems will lead to some qualitative predictions for the spreading depending on the structure of the nonlinearity.   however, a full quantitative relation of the microscopic dynamics and the macroscopic diffusion will remain out of reach. *
the existence of an unparticle sector, weakly coupled to the standard model, would have a profound impact on supernova ( sn ) physics.   emission of energy into the unparticle sector from the core of sn  1987a would have significantly shortened the observed neutrino burst. the unparticle interaction with nucleons, neutrinos, electrons and muons   is constrained to be so weak that it is unlikely to provide any missing - energy signature at colliders.   one important exception are models where scale invariance in the hidden sector is broken by the higgs vacuum expectation value. in this case   the sn emission is suppressed by threshold effects.
the structure of the @xmath0 reconstructed phase on sapphire ( 0001 ) surface is investigated by means of a simulation based on the energy minimization.   the interaction between al adatoms is described with the semi - empirical many - body sutton - chen potential, corrected for the charge transfer between the metallic overlayer and the substrate.   the interactions between the al adatoms and sapphire substrate are described with a simple three - dimensional potential field which has the hexagonal periodicity of sapphire surface.   our energy analysis gave evidence that the structure which is observed at room temperature is in fact a frozen high - temperature structure.   in accordance with the x - ray scattering, a hexagonal domain pattern separated by domain walls has been found.   the al adatoms, distributed in two monolayers, are ordered and isomorphic to metallic al(111 ) in the domains and disordered in the domain walls.   the main reason for the rotational reconstruction is the lattice misfit between the metallic al and sapphire  .    surface relaxation and reconstruction.   sapphire.   surface thermodynamics. computer simulations.   pacs numbers : 68.35 bs, 68.35 md, 61.50 ah, 68.10 jy
in this paper, we investigate the applicability of the astrometric method to the determination of the lens parameters for gravitational microlensing events toward both the lmc and the galactic bulge. for this analysis  , we investigate the dependency of the astrometrically determined angular einstein ring radius, @xmath0, on the lens parameters by testing various types of events.   in addition, by computing @xmath0 for events with lensing parameters which are the most probable for a given lens mass under the standard models of galactic matter density and velocity distributions, we determine the expected distribution of the uncertainties as a function of lens mass. from this study, we find that the values of the angular einstein ring radius are expected to be measured with uncertainties @xmath1 up to a lens mass of @xmath2 for both galactic disk - bulge and halo - lmc events with a moderate observational strategy.   the uncertainties are relatively large for galactic bulge - bulge self - lensing events, @xmath3 for @xmath2, but they can be substantially reduced by adopting more aggressive observational strategies. we also find that although astrometric observations can be performed for most photometrically detected galactic bulge events, a significant fraction ( @xmath4 ) of lmc events can not be astrometrically observed due to the faintness of their source stars.    6.5 in    ccc 1 & 1 & 1 + 1 & 1 & 1 + 4 & 3 & 8    submitted to _   monthly notices of the royal astronomy society _ : sep 26, 1998    preprint : cnu - a&ss-07/98
we have measured astrometry for members of the orion nebula cluster with images obtained in 2015 with the wide field camera 3 on board the _ hubble space telescope_. by comparing those data to previous measurements with nicmos on _ hubble _ in 1998, we have discovered that a star in the kleinmann - low nebula, source x from @xcite, is moving with an unusually high proper motion of 29  mas  yr@xmath0, which corresponds to 55  km  s@xmath0 at the distance of orion.   previous radio observations have found that three other stars in the kleinmann - low nebula ( bn and sources i and n ) have high proper motions ( 514  mas  yr@xmath0 ) and were near a single location @xmath1540 years ago, and thus may have been members of a multiple system that dynamically decayed.   the proper motion of source x is consistent with ejection from that same location 540 years ago, which provides strong evidence that the dynamical decay did occur and that the runaway star bn originated in the kleinmann - low nebula rather than the nearby trapezium cluster.   however, our constraint on the motion of source  n is significantly smaller than the most recent radio measurement, which indicates that it did not participate in the event that ejected the other three stars.
when a superconducting sample is submitted to a sufficiently strong external magnetic field, the superconductivity of the material is lost. in this paper   we prove that this effect does not, in general, take place at a unique value of the external magnetic field strength.   indeed, for a sample in the shape of a narrow annulus the set of magnetic field strengths for which the sample is superconducting is not an interval.   this is a rigorous justification of the little  parks effect.   we also show that the same oscillation effect can happen for disc - shaped samples if the external magnetic field is non - uniform. in this case   the oscillations can even occur repeatedly along arbitrarily large values of the ginzburg   landau parameter @xmath0.   the analysis is based on an understanding of the underlying spectral theory for a magnetic schrdinger operator.   it is shown that the ground state energy of such an operator is not in general a monotone function of the intensity of the field, even in the limit of strong fields.
based on signaling process on complex networks, a method for identification community structure is proposed. for a network with @xmath0 nodes,   every node is assumed to be a system which can send, receive, and record signals.   each node is taken as the initial signal source once to inspire the whole network by exciting its neighbors and then the source node is endowed a @xmath0d vector which recording the effects of signaling process.   so by this process, the topological relationship of nodes on networks could be transferred into the geometrical structure of vectors in @xmath0d euclidian space.   then the best partition of groups is determined by @xmath1-statistic and the final community structure is given by fuzzy @xmath2-means clustering method ( fcm ).   this method can detect community structure both in unweighted and weighted networks without any extra parameters.   it has been applied to ad hoc networks and some real networks including zachary karate club network and football team network.   the results are compared with that of other approaches and the evidence indicates that the algorithm based on signaling process is effective.   * keyword * : complex network, community structure, signaling algorithm, fcm    * pacs * : 89.75.hc, 89.75.fb, 89.65.-s
the effects of a radiation field ( rf ) on the interaction process of a relativistic electron beam ( reb ) with an electron plasma are investigated. the stopping power of the test electron averaged with a period of the rf   has been calculated assuming an underdense plasma, @xmath0, where @xmath1 is the frequency of the rf and @xmath2 is the plasma frequency. in order to highlight the effect of the radiation field we present a comparison of our analytical and numerical results obtained for nonzero rf with those for vanishing rf.   in particular, it has been shown that the weak rf increases the mean energy loss for small angles between the velocity of the reb and the direction of polarization of the rf while decreasing it at large angles.   furthermore, the relative deviation of the energy loss from the field - free value is strongly reduced with increasing the beam energy.   special case of the parallel orientation of the polarization of the rf with respect to the beam velocity has been also considered. at high - intensities of the rf   two extreme regimes have been distinguished when the excited harmonics cancel effectively each other reducing strongly the energy loss or increasing it due to the constructive interference.   moreover, it has been demonstrated that the energy loss of the ultrarelativistic electron beam increases systematically with the intensity of the rf exceeding essentially the field - free value.   * keywords : * relativistic electron beam ; radiation field ; stopping power
we report the x - ray detection of two @xmath0 infrared - selected galaxy clusters from the irac shallow cluster survey ( iscs ).   we present new data from the _ hubble space telescope _ and the w.  m.  keck observatory that spectroscopically confirm cluster iscs  j1432.4 + 3250 at @xmath1, the most distant of 18 confirmed @xmath2 clusters in the iscs to date.   we also present new spectroscopy for iscs  j1438.1 + 3414, previously reported at @xmath3, and measure its dynamical mass.   clusters iscs  j1432.4 + 3250  and iscs  j1438.1 + 3414  are detected in 36ks and 143ks _ chandra _  exposures at significances of @xmath4 and @xmath5, from which we measure total masses of @xmath6 and @xmath7, respectively.   the consistency of the x - ray and dynamical properties of these high redshift clusters further demonstrates that the iscs is robustly detecting massive clusters to at least @xmath8.
it has been suggested that both x - ray bursters and millisecond radio pulsars may be strange ( quark ) stars, rather than neutron stars.   confirming ( or rejecting ) this suggestion may require knowing what role strong - field effects of general relativity play in the accretion flow of the compact x - ray source in low - mass x - ray binaries ( lmxbs ).   we discuss the range of rotational and orbital frequencies, and of masses expected in various models of strange stars, and compare them with observational constraints, suggested by the observed frequencies of khz qpos.   we explain why future observations of transients ( such as sax j  1808.4 - 3658 ) may be crucial to understanding the precise nature of the accreting source. for flattened ( e.g., rapidly rotating ) distributions of matter, an innermost ( marginally ) stable orbit may be present even if relativistic effects are negligible.   depending on the stellar rotation rate, the same value of orbital frequency in the innermost stable orbit ( say, 0.9 khz ) can correspond to a star of mass equal to @xmath0, @xmath1, @xmath2, @xmath3, or less.   
our simultaneous multicolor ( @xmath0 ) circular polarimetry has revealed nearly sinusoidal variation over the wd spin cycle, and almost symmetric positive and negative polarization excursions.   maximum amplitudes are observed in the @xmath1 and @xmath2 bands ( @xmath33% ).   this is the first time that polarization peaking in the _ blue _ has been discovered in an ip, and suggests that v405 aur is the highest magnetic field ip found so far.   the polarized flux spectrum is similar to those found in _   polars _ with magnetic fields in the range @xmath4 25 - 50 mg.   our low resolution circular spectropolarimetry has given evidence of transient features which can be fitted by cyclotron harmonics @xmath5= 6, 7, and 8, at a field of @xmath6 mg, consistent with the broad - band polarized flux spectrum.   timings of the circular polarization zero crossovers put strict upper limits on wd spin period changes and indicate that the wd in v405 aur is currently accreting closely at the spin equilibrium rate, with very long synchronization timescales, @xmath7 yr. for the observed spin to orbital period ratio, @xmath8=0.0365, and @xmath9 4.15 hr, existing numerical accretion models predict spin equilibrium condition with @xmath4 30 mg if the mass ratio of the binary components is @xmath10 0.4.   the high magnetic field makes v405 aur a likely candidate as a progenitor of a polar.
we present a 2 - 10 kev asca observation of the field around the soft gamma repeater sgr1627 - 41.   a quiescent x - ray source was detected in this observation whose position was consistent both with that of a recently discovered _ bepposax x - ray source and with the interplanetary network localization for this sgr. in 2 - 10 kev x - rays, the spectrum of the x - ray source may be fit equally well by a power law, blackbody, or bremsstrahlung function, with unabsorbed flux @xmath0.   we do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both noted in the earlier _ bepposax observations. _ _
the impact of bound states in landauer - bttiker scattering approach to non - equilibrium quantum transport is investigated.   we show that the noise power at frequency @xmath0 is sensitive to all bound states with energies @xmath1 satisfying @xmath2.   we derive the exact expression of the bound state contribution and compare it to the one produced by the scattering states alone.   the theoretical and experimental consequences of this result are discussed.   s    h uu l o * v *    * quantum transport in presence of bound states - noise power * +    mihail mintchev +    luca santoni +    paul sorba +
the modulated wideband converter ( mwc ) is a recently proposed analog - to - digital converter ( adc ) based on compressive sensing ( cs ) theory. unlike conventional adcs, its quantization reference voltage, which is important to the system performance, does not equal the maximum amplitude of original analog signal. in this paper,   the quantization reference voltage of the mwc is theoretically analyzed and the conclusion demonstrates that the reference voltage is proportional to the square root of @xmath0, which is a trade - off parameter between sampling rate and number of channels.   further discussions and simulation results show that the reference voltage is proportional to the square root of @xmath1 when the signal consists of @xmath2 narrowband signals  .    reference voltage, modulated wideband converter ( mwc ), compressive sensing ( cs ).
in this paper we define the magnitude of metric spaces using measures rather than finite subsets as had been done previously and show that this agrees with earlier results. an explicit formula for the magnitude of an @xmath0-sphere with its intrinsic metric   is given.   for an arbitrary homogeneous riemannian manifold the leading terms of the asymptotic expansion of the magnitude are calculated and expressed in terms of the volume and total scalar curvature of the manifold. in the particular case of a homogeneous surface   the form of the asymptotics can be given exactly up to vanishing terms and this involves just the area and euler characteristic in the way conjectured for subsets of euclidean space in previous work.
the two components of radio emission, above and below 86 ghz respectively, from the galactic center source@xmath0sgr a * can be naturally explained by the hybrid of thermal and nonthermal electrons in hot accretion flows ( e.g., radiatively inefficient accretion flow, riaf, e.g., yuan et al.   2003 ).   we further apply this model to a sample of nearby low - luminosity active galactic nuclei ( llagns ), which are also believed to be powered by the riaf.   we selected the llagns with only compact radio cores according to the high - resolution radio observations, and the sources observed with jets or jet - like features are excluded.   we find that the radio emission of llagns is severely underpredicted by pure riaf model, and can be naturally explained by the riaf model with a hybrid electron population consisting of both thermal and nonthermal particles.   our model can roughly reproduce the observed anti - correlation between the mass - corrected radio loudness and eddington ratio for the llagns in our sample.   we further model the spectral energy distributions of each source in our sample, and find that roughly all sources can be well fitted if a small fraction of the steady state electron energy is ejected into the nonthermal electrons.   the size of radio emission region of our model is around several thousand gravitational radii, which is also roughly consistent with the recent high - resolution vlbi observations for some nearby llagns.
we discuss the performance of low - density - parity - check ( ldpc ) codes decoded by means of linear programming ( lp ) at moderate and large signal - to - noise - ratios ( snr ). utilizing a combination of the previously introduced pseudo - codeword - search method and a new  dendro " trick, which allows us to reduce the complexity of the lp decoding  , we analyze the dependence of the frame - error - rate ( fer ) on the snr. under   maximum - a - posteriori ( map ) decoding the dendro - code, having only checks with connectivity degree three, performs identically to its original code with high - connectivity checks. for a number of popular ldpc codes performing over the additive - white - gaussian - noise ( awgn ) channel we found that either an error - floor sets at a relatively low snr, or otherwise a transient asymptote, characterized by a faster decay of fer with the snr increase, precedes the error - floor asymptote.   we explain these regimes in terms of the pseudo - codeword spectra of the codes.   ldpc codes, linear programming decoding, error - floor, pseudo - codewords
in this talk we show how it is possible to apply the general scheme of effective scattering theory to the description of hadronic processes.   we perform the numerical tests of the tree level bootstrap constraints for renormalization prescriptions in the case of elastic kaon - nucleon scattering process.
we propose a generalization of the discrete klein - gordon models free of the peierls - nabarro barrier derived in nonlinearity * 12 *, 1373 ( 1999 ) and phys. rev.   e * 72 *, 035602(r ) ( 2005 ), such that they support not only kinks but a one - parameter set of exact static solutions.   these solutions can be obtained iteratively from a two - point nonlinear map whose role is played by the discretized first integral of the static klein - gordon field, as suggested in j. phys.   a * 38 *, 7617 ( 2005 ).   we then discuss some discrete @xmath0 models free of the peierls - nabarro barrier and identify for them the full space of available static solutions, including those derived recently in phys.   rev.   e * 72 * 036605 ( 2005 ) but not limited to them.   these findings are also relevant to standing wave solutions of discrete nonlinear schrdinger models  . we also study stability of the obtained solutions. as an interesting aside  , we derive the list of solutions to the continuum @xmath0 equation that fill the entire two - dimensional space of parameters obtained as the continuum limit of the corresponding space of the discrete models.
the perfect absorption of light in subwavelength thickness layers generally relies on exotic materials, metamaterials or thick metallic gratings.   here we demonstrate that total light absorption can be achieved in ultra - thin gratings composed of conventional materials, including relatively weakly - absorbing semiconductors, which are compatible with optoelectronic applications such as photodetectors and optical modulators.   we fabricate a 41 nm thick antimony sulphide grating structure that has a measured absorptance of @xmath0 at a visible wavelength of 591 nm, in excellent agreement with theory.   we infer that the absorption within the grating is @xmath1, with only @xmath2 within the silver mirror.   a planar reference sample absorbs @xmath3 at this wavelength.
contracts for difference ( cfds ) are forwards on the spread between an area price and the system price. together with the system price forwards, these products are used to hedge the area price risk in the nordic electricity market.   the cfds are typically available for the next two months, three quarters and three years.   this is fine, except that cfds are not traded at nasdaq omx commodities for every nord pool spot price area.   we therefore ask the hypothetical question : what would the cfd market price have been, say in the price area no2, if it had been traded?   we build regression models for each observable price area, and use bayesian elicitation techniques to obtain prior information on how similar the different price areas are to forecast the price in an area where cfds are not traded.    corresponding author.   e - mail : egil@hi.is
using the qcd dipole picture of the hard bfkl pomeron, we perform a 3 parameter fit analysis of the recent inclusive structure function experimental mesurements at small-@xmath0 and intermediate @xmath1. as a byproduct, the longitudinal structure function and the gluon distribution   are predicted without further adjustments.   the data description is quite reasonable, being timely a further study using resummed nlo bfkl kernels along the lines of recent theoretical developments.
we investigate the weakly non - linear evolution of cosmic gravitational clustering in phase space by looking at the zeldovich solution in the discrete wavelet transform ( dwt ) representation.   we show that if the initial perturbations are gaussian, the relation between the evolved dwt mode and the initial perturbations in the weakly non - linear regime is quasi - local.   that is, the evolved density perturbations are mainly determined by the initial perturbations localized in the same spatial range.   furthermore, we show that the evolved mode is monotonically related to the initial perturbed mode.   thus large ( small ) perturbed modes statistically correspond to the large ( small ) initial perturbed modes.   we test this prediction by using qso ly@xmath0 absorption samples.   the results show that the weakly non - linear features for both the transmitted flux and identified forest lines are quasi - localized.   the locality and monotonic properties provide a solid basis for a dwt scale - by - scale gaussianization reconstruction algorithm proposed by feng & fang ( feng & fang, 2000 ) for data in the weakly non - linear regime. with the zeldovich solution  , we find also that the major non - gaussianity caused by the weakly non - linear evolution is local scale - scale correlations.   therefore, to have a precise recovery of the initial gaussian mass field, it is essential to remove the scale - scale correlations.
q & a ( quantum electrodynamics test and search for axion ) experiment was first proposed in 1994 and a 3.5 m high - finesse fabry - perot prototype detector extendable to 7 m has been built and tested.   we use x - pendulums and automatic control schemes developed by the gravitational - wave detection community for mirror suspension and cavity control. in this paper  , we first give an overview of ellipticity detection scheme of q & a experiment and compare it with other experiments in which fabry - perot cavities are also used to multiply the effectiveness of the magnetic field.   we then present the displacement spectra of our suspension system and use the data for designing automatic alignment control.   results and experiences gained in the previous test runs have pointed out that the lateral and rotational motion of our suspension system could cause noises and laser off - locks from the fabry - perot cavity, and downgrade the ellipticicy detection sensitivity. to fix this problem, i.e., to maintain the alignment between cavity mirrors and incoming laser beam, and to minimize detection noises  , we implement an automatic alignment control scheme based on the ward differential wavefront sensing technique. to improve ellipsometry resolution  , we use new polarizers of extinction ratio smaller than @xmath0.
we present a detailed analysis of the effective force between two smooth spherical colloids floating at a fluid interface due to deformations of the interface.   the results hold in general and are applicable independently of the source of the deformation provided the capillary deformations are small so that a superposition approximation for the deformations is valid. we conclude that an effective long  ranged attraction is possible if the net force on the system does not vanish.   otherwise, the interaction is short  ranged and can not be computed reliably based on the superposition approximation. as an application  , we consider the case of like  charged, smooth nanoparticles and electrostatically induced capillary deformation.   the resulting long  ranged capillary attraction can be easily tuned by a relatively small external electrostatic field, but it can not explain recent experimental observations of attraction if these experimental systems were indeed isolated.
a coarsened model for a binary system with limited miscibility of components is proposed ; the system is described in terms of structural states in small parts of the material.   the material is assumed to have two alternative types of crystalline local arrangements associated with two components of the alloy.   fluctuating characteristics of a cluster are the type and the space orientation of its crystalline arrangement.   there are two different phase transitions in the model system, an orientation order - disorder transition representing melting, and a phase transition between phases differing in concentration of components.   depending on the parameters characterizing the interaction in the system, this last transition may take place both in the crystalline and in the amorphous ( molten ) phase.   a special approximation is used to study the thermodynamics of the system.   the calculated phase diagram describes, at least qualitatively, the most important features of a binary system.
starting from the coupling of a relativistic quantum particle to the curved schwarzschild space - time, we show that the dirac  schwarzschild problem has bound states and calculate their energies including relativistic corrections.   relativistic effects are shown to be suppressed by the gravitational fine - structure constant @xmath0, where @xmath1 is newton s gravitational constant, @xmath2 is the speed of light and @xmath3 and @xmath4 are the masses of the two particles.   the kinetic corrections due to space - time curvature are shown to lift the familiar @xmath5 degeneracy of the energy levels of the hydrogen atom.   we supplement the discussion by a consideration of an attractive scalar potential, which, in the fully relativistic dirac formalism, modifies the mass of the particle according to the replacement @xmath6, where @xmath7 is the radial coordinate.   we conclude with a few comments regarding the @xmath5 degeneracy of the energy levels, where @xmath8 is the principal quantum number, and @xmath9 is the total angular momentum, and illustrate the calculations by way of a numerical example.
in this paper spatial correlations of parallel edge dislocations are studied. after closing a hierarchy of equations for the many - particle density functions by the kirkwood superposition approximation  , we derive evolution equations for the correlation functions.   it is found that these resulting equations and those governing the evolution of density fields of total as well as geometrically necessary dislocations around a single edge dislocation are formally the same.   the second case corresponds to the already described phenomenon of debye screening of an individual dislocation.   this equivalence of the correlation functions and screened densities is demonstrated also by discrete dislocation dynamics simulation results, which confirm the physical correctness of the applied kirkwood superposition approximation.   relation of this finding and the linear response theory in thermal systems is also discussed.
in order to study chromospheric magnetosonic wave propagation including, for the first time, the effects of ion - neutral interactions in the partially ionized solar chromosphere, we have developed a new multi - fluid computational model, accounting for ionization and recombination reactions in gravitationally stratified magnetized collisional media.   the two - fluid model used in our 2d numerical simulations treats neutrals as a separate fluid and considers charged species ( electrons and ions ) within the resistive mhd approach with coulomb collisions and anisotropic heat flux determined by braginskii s transport coefficients.   the electromagnetic fields are evolved according to the full maxwell equations and the solenoidality of the magnetic field is enforced with a hyperbolic divergence cleaning scheme.   the initial density and temperature profiles are similar to val iii chromospheric model in which dynamical, thermal and chemical equilibrium are considered to ensure comparison to existing mhd models and avoid artificial numerical heating. in this initial setup   we include simple homogeneous flux tube magnetic field configuration and an external photospheric velocity driver to simulate the propagation of mhd waves in the partially ionized reactive chromosphere.   in particular, we investigate the loss of chemical equilibrium and the plasma heating related to the steepening of fast magnetosonic wave fronts in the gravitationally stratified medium.
the impact of curvature divergences on physical observers in a black hole space - time which, nonetheless, is geodesically complete is investigated.   this space - time is an exact solution of certain extensions of general relativity coupled to maxwell s electrodynamics and, roughly speaking, consists on two reissner - nordstrm ( or schwarzschild or minkowski ) geometries connected by a spherical wormhole near the center.   we find that, despite the existence of infinite tidal forces, causal contact is never lost among the elements making up the observer.   this suggests that curvature divergences may not be as pathological as traditionally thought.
in this paper we consider a problem of searching a space of predictive models for a given training data set.   we propose an iterative procedure for deriving a sequence of improving models and a corresponding sequence of sets of non - linear features on the original input space. after a finite number of iterations @xmath0,   the non - linear features become @xmath1-degree polynomials on the original space.   we show that in a limit of an infinite number of iterations derived non - linear features must form an associative algebra : a product of two features is equal to a linear combination of features from the same feature space for any given input point.   because each iteration consists of solving a series of convex problems that contain all previous solutions, the likelihood of the models in the sequence is increasing with each iteration while the dimension of the model parameter space is set to a limited controlled value.
in this paper we report that a bright, x - ray source in the antennae galaxies ( ngc 4038/9 ), previously identified as an ultra - luminous x - ray source, is in fact a background quasar.   we identify an isolated infrared and optical counterpart within @xmath0 the x - ray source x-37. after acquiring   an optical spectrum of its counterpart, we use the narrow  and broad h@xmath1 emission lines to identify x-37 as a quasar at a redshift of z=0.26. through a @xmath2, @xmath3, and @xmath4 photometric analysis,   we demonstrate that most of the observable light along this line of sight is from the quasar.   we discuss the implications of this discovery and the importance of acquiring spectra for optical and ir counterparts to ulxs.
one of the key sources of transverse impedance in the lhc has been the secondary graphite collimators that sit close to the beam at all energies.   this limits the stable bunch intensity due to transverse coupled - bunch instabilities and transverse mode coupling instability. to counteract this,   new secondary collimators have been proposed for the phase ii upgrade of the lhc collimation system.   a number of designs based on different jaw materials and mechanical designs have been proposed.   a comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase i secondary collimator design.
for classical hamiltonian systems, the adiabatic condition may fail at some critical points.   however, the breakdown of the adiabatic condition does not always make the adiabatic evolution be destroyed. in this paper, we suggest a supplemental condition of the adiabatic evolution for the fixed points of classical hamiltonian systems when the adiabatic condition breaks down at the critical points. as an example, we investigate the adiabatic evolution of the fixed points of a classical hamiltonian system which has a number of applications.
we investigate the charge distributions for the @xmath0 and @xmath1 quarks in transverse coordinate space in a light - front quark - diquark model for the nucleons using the overlaps of the wave functions constructed from the soft - wall ads / qcd prediction.   we have also obtained the charge distributions for proton and neutron in transverse coordinate space and compared it with the distributions obtained in impact - parameter space.   further, we study the longitudinal momentum distributions using the wave functions in the transverse coordinate space.   we have also shown the explicit fermionic and bosonic contributions for different struck @xmath0 and @xmath1 quarks.
the spectral shape of ir emission from herbig ae / be stars has been invoked as evidence for accretion disks around high - mass protostars.   instead, we present here models based on spherical envelopes with @xmath0 dust density profile that successfully explain the observed spectral shapes.   the spectral energy distributions ( seds ) of eight primary candidates for protostellar disks are fitted in detail for all wavelengths available, from visual to far ir.   the only envelope property adjusted in individual sources is the overall visual optical depth, and it ranges from 0.3 to 3. in each case, our models properly reproduce the data for both ir excess, visual extinction and reddening.   the success of our models shows that accretion disks can not make a significant contribution to the radiation observed in these pre - main sequence stars.   = =
we calculate the radiative heat transfer between two identical metallic one - dimensional lamellar gratings. to this aim   we present and exploit a modification to the widely - used fourier modal method, known as adaptive spatial resolution, based on a stretch of the coordinate associated to the periodicity of the grating.   we first show that this technique dramatically improves the rate of convergence when calculating the heat flux, allowing to explore smaller separations.   we then present a study of heat flux as a function of the grating height, highlighting a remarkable amplification of the exchanged energy, ascribed to the appearance of spoof - plasmon modes, whose behavior is also spectrally investigated. differently from previous works,   our method allows us to explore a range of grating heights extending over several orders of magnitude. by comparing our results to recent studies we find a consistent quantitative disagreement with some previously obtained results going up to 50%. in some cases,   this disagreement is explained in terms of an incorrect connection between the reflection operators of the two gratings.
gravitational wave astronomy will require the coordinated analysis of data from the global network of gravitational wave observatories.   questions of how to optimally configure the global network arise in this context.   we have elsewhere proposed a formalism which is employed here to compare different configurations of the network, using both the coincident network analysis method and the coherent network analysis method.   we have constructed a network model to compute a figure - of - merit based on the detection rate for a population of standard - candle binary inspirals.   we find that this measure of network quality is very sensitive to the geographic location of component detectors under a coincident network analysis, but comparatively insensitive under a coherent network analysis.
after the precise observations of the cosmic microwave background ( cmb ) anisotropy power spectrum, attention is now being focused on higher order statistics of the cmb anisotropies.   since linear evolution preserves the statistical properties of the initial conditions, observed non - gaussianity of the cmb will mirror primordial non - gaussianity.   single field slow - roll inflation robustly predicts negligible non - gaussianity so an indication of primordial non - gaussianity will suggest alternative scenarios need to be considered. in this paper   we calculate the information on primordial non - gaussianities encoded in the polarization of the cmb. after deriving the optimal weights for a cubic estimator we evaluate the signal - to - noise ratio @xmath0 of the estimator for wmap, planck and an ideal cosmic variance limited experiment.   we find that when the experiment can observe cmb polarization with good sensitivity, the sensitivity to primordial non - gaussianity increases by roughly a factor of two.   we also test the weakly non - gaussian assumption used to derive the optimal weight factor by calculating the degradation factor produced by the gravitational lensing induced connected four - point function.   the physical scales in the radiative transfer functions are largely irrelevant for the constraints on the primordial non - gaussianity.   we show that the total @xmath1 is simply proportional to the number of observed pixels on the sky.
we show that the failure of the delaney - greer ( dg ) variational ansatz for transport demonstrated by us in phys.  rev.   b * 80 *, 165301 ( 2009 ) ( i ) is not related to an unsuitable constraint that prevents a broken time - reversal symmetry or to real orbitals, as dg incorrectly claim.   the complex orbitals suggested by them as a way - out solution merely represent a particular case of the general case considered by us in i, which do not in the least affect our conclusion. in conjunction with the issues raised by the dg s comment,   we show that the dg wigner conditions can erroneously constrain _ outgoing _ and not incoming charge carriers and present an example revealing that the sign of the `` momentum '' @xmath0 of the wigner function @xmath1 is not necessarily associated with the direction of motion in the real world.   we also discuss a general reason why transport approaches which, like the dg s, are solely based on information on an isolated nanocluster are incorrect.
a new perturbative scheme is proposed for the evaluation of the free energy density of field theories at finite temperature.   the screened loop expansion takes into account exactly the phenomenon of screening in thermal propagators.   the approach is tested in the @xmath0-component scalar field theory at 2-loop level and also at 3-loop in the large @xmath0 limit.   the perturbative series generated by the screened loop expansion shows much better numerical convergence than previous expansions generated in powers of the quartic coupling.   bi - tp 97/06 + itp budapest rep.   529 + february 1997 +     +   +    : 11.10.wx, 12.38.mh + _ keywords : _ qcd, scalar field theory, free energy density, debye screening, loop expansion, gap equation, high - t expansion
i briefly summarize the parallel sessions on automated calculation and simulation systems for high energy particle physics phenomenology at acat2002 ( moscow state university, june 2002 ) and present a short overview over the current status of the field and try to identify the important trends.   to : hep-ph@xxx.lanl.gov subject : put     + title : automated calculation and simulation systems author : thorsten ohl ( university of wuerzburg ) comments : 4 pages, latex, to appear in the proceedings of acat 2002.   report - no : wue - itp-2002 - 031 + i briefly summarize the parallel sessions on automated calculation and simulation systems for high energy particle physics phenomenology at acat 2002 ( moscow state university, june 2002 ) and present a short overview over the current status of the field and try to identify the important trends.
motivated by khovanov homology and relations between the jones polynomial and graph polynomials, we construct a homology theory for embedded graphs from which the chromatic polynomial can be recovered as the euler characteristic. for plane graphs, we show that our chromatic homology can be recovered from the khovanov homology of an associated link.   we apply this connection with khovanov homology to show that the torsion - free part of our chromatic homology is independent of the choice of planar embedding of a graph.   we extend our construction and categorify the bollobs - riordan polynomial ( a generalisation of the tutte polynomial to embedded graphs ).   we prove that both our chromatic homology and the khovanov homology of an associated link can be recovered from this categorification.   = 1
presence of dust in galaxies removes half or more of the stellar energy from the uv  optical budget of the universe and has profound impact on our understanding of how galaxies evolve.   measures of opacity in local galaxies are reviewed together with widely used theoretical and empirical methods for quantifying its effects.   existing evidence shows that the dust content of nearby galaxies depends not only on their morphology, but also on their luminosity and activity level.   a digression is devoted to starbursts in view of their potential relevance for measures of opacity in distant galaxies.   scarcity of coherent multiwavelength datasets hampers our ability to derive reliable obscuration estimates in intermediate and high redshift galaxies.   this, in turn, limits the reliability of inferred physical quantities, such as star formation rates, stellar population ages, galaxy luminosity functions, and others.
derived equivalences between finite dimensional algebras do, in general, not pass to centraliser ( or other ) subalgebras, nor do they preserve homological invariants of the algebras, such as global or dominant dimension.   we show that, however, they do so for large classes of algebras described in this article.   algebras @xmath0 of @xmath1-dominant dimension at least one have unique largest non - trivial self - injective centraliser subalgebras @xmath2.   a derived restriction theorem is proved : a derived equivalence between @xmath0 and @xmath3 implies a derived equivalence between @xmath2 and @xmath4.   two methods are developed to show that global and dominant dimension are preserved by derived equivalences between algebras of @xmath1-dominant dimension at least one with anti - automorphisms preserving simples, and also between almost self - injective algebras.   one method is based on identifying particular derived equivalences preserving homological dimensions, while the other method identifies homological dimensions inside certain derived categories.   in particular, derived equivalent cellular algebras have the same global dimension. as an application,   the global and dominant dimensions of blocks of quantised schur algebras with @xmath5 are completely determined.    * keywords *   derived equivalence.   dominant dimension. global dimension.   schur algebras.     corresponding author. ]
we study the effect of the ferromagnetic ( fm ) contacts on the spin accumulation in the lateral spin valve system for the collinear magnetization configurations. when an additional fm electrode is introduced in the all - metallic lateral spin - valve system, we find that the transresistance can be fractionally suppressed or very weakly influenced depending on the position of the additional fm electrode, and relative magnitudes of contact resistance and the bulk resistance defined over the spin diffusion length.   nonlocal spin signals such as nonlocal voltage drop and leakage spin currents are independent of the magnetization orientation of the additional fm electrode.   even when the additional contact is nonmagnetic, nonlocal spin signals can be changed by the spin current leaking into the nonmagnetic electrode.
we use fully self - consistent @xmath0-body simulations of barred galaxies to show that dynamical friction from a dense dark matter halo dramatically slows the rotation rate of bars.   our result supports previous theoretical predictions for a bar rotating within a massive halo. on the other hand, low density halos, such as those required for maximum disks,   allow the bar to continue to rotate at a high rate.   there is somewhat meager observational evidence indicating that bars in real galaxies do rotate rapidly and we use our result to argue that dark matter halos must have a low central density in all high surface brightness disk galaxies, including the milky way.   bars in galaxies that have larger fractions of dark matter should rotate slowly, and we suggest that a promising place to look for such candidate objects is among galaxies of intermediate surface brightness.   = 1 psfig    # 1to 0pt#1
this work studies the optical emission line properties of a sample of 155 low - redshift bright x - ray selected rosat seyfert  1 type agn for which adequate signal - to - noise ratio spectroscopic observations are available.   we measured emission line properties by performing multi - component fits to the emission line profiles, covering the effect of blended iron emission.   we also obtained continuum parameters, including 250ev x - ray luminosities derived from the rosat database. in addition, the measured properties are gathered for a correlation analysis, which confirms the well - known relations between the strengths of fe  ii,  emission and the x - ray slope.   we also detect striking correlations between h@xmath0 redshift ( or blueshift ), flux ratios of fe  ii to h@xmath0 broad component and  to h@xmath0 narrow component.   these trends are most likely driven by the eddington ratio.
in this paper we propose a fast algorithm for trivariate interpolation, which is based on the partition of unity method for constructing a global interpolant by blending local radial basis function interpolants and using locally supported weight functions.   the partition of unity algorithm is efficiently implemented and optimized by connecting the method with an effective cube - partition searching procedure.   more precisely, we construct a cube structure, which partitions the domain and strictly depends on the size of its subdomains, so that the new searching procedure and, accordingly, the resulting algorithm enable us to efficiently deal with a large number of nodes. complexity analysis and numerical experiments   show high efficiency and accuracy of the proposed interpolation algorithm.   meshless approximation, fast algorithms, partition of unity methods, radial basis functions, scattered data.    65d05, 65d15, 65d17.
the paper presents an integrated view of the population structure and its role in establishing the ionisation state of light elements in dynamic, finite density, laboratory and astrophysical plasmas.   there are four main issues, the generalised collisional - radiative picture for metastables in dynamic plasmas with maxwellian free electrons and its particularising to light elements, the methods of bundling and projection for manipulating the population equations, the systematic production / use of state selective fundamental collision data in the metastable resolved picture to all levels for collisonal - radiative modelling and the delivery of appropriate derived coefficients for experiment analysis.   the ions of carbon, oxygen and neon are used in illustration.   the practical implementation of the methods described here is part of the adas project.
we study the absorbing phase transitions in coupled directed percolation ( dp ) processes with @xmath0-species particles in one dimension.   the interspecies coupling is linear, bidirectional, and excitatory.   we find that the presence of a spontaneous annihilation process @xmath1 is essential in stabilizing the absorbing phase ( vacuum ). in the coupled contact processes, the vacuum is stable and the system exhibits dp type transitions, regardless of the coupling strength, for all @xmath0.   however, in the coupled branching annihilation random walks with one offspring ( baw ), where particle annihilations occur only through binary diffusion processes @xmath2, the vacuum becomes unstable with respect to an arbitrarily small branching rate in a sufficiently strong coupling regime for @xmath3.   the @xmath4 baw exhibits the dp type transition for any coupling strength, but the inclusion of interspecies hard core ( hc ) interaction makes the vacuum unstable again and the system is always active in a strong coupling regime.   critical behavior near the zero branching point is characterized by the scaling exponents, @xmath5 and @xmath6, regardless of the presence of hc interaction.   we also discuss the effects of the asymmetric coupling.
we present an asymptotically flat supersymmetric black lens solution with the horizon topology @xmath0 in the five - dimensional minimal ungauged supergravity.   we show that the black lens carries a mass, two independent angular momenta, electric charge and @xmath1 magnetic fluxes, among which only the @xmath2 quantities are independent.
existing multicasting schemes for massive content delivery do not fully utilize multicasting opportunities in delay tolerant content - oriented applications. in this paper, we propose a novel temporal - spatial aggregation - based multicasting scheme in a large - scale cache - enabled wireless network  . the proposed scheme can efficiently exploit multicasting opportunities in asynchronous content requests to improve spectral efficiency. by making use of the delay tolerance of elastic services,   the proposed scheme achieves a better energy - throughput - delay tradeoff. utilizing tools from stochastic geometry,   we derive a tractable expression for the successful transmission probability in the general region. using asymptotic approximations, we derive closed form successful transmission probabilities in the large delay region as well as the large and small user density regions.   the asymptotic results reveal that the successful transmission probability increases and the energy consumption decreases at the cost of delay increase in these asymptotic regions.   the analysis in this paper provides a new understanding of the energy - throughput - delay tradeoff for massive content delivery in large - scale cache - enabled wireless networks.
the bright star 55  cancri is known to host five planets, including a transiting super - earth.   we use the chara array to directly determine the following of 55  cnc s stellar astrophysical parameters : @xmath0, @xmath1 k. planet 55  cnc f ( @xmath2 ) spends the majority of the duration of its elliptical orbit in the circumstellar habitable zone ( 0.671.32 au ) where, with moderate greenhouse heating, it could harbor liquid water.   our determination of 55  cancri s stellar radius allows for a model - independent calculation of the physical diameter of the transiting super - earth 55  cnc e ( @xmath3 ), which, depending on the assumed literature value of planetary mass, implies a bulk density of 0.76 @xmath4 or 1.07 @xmath4.
we present optical spectroscopy of all 49 radio galaxies in the 7c  i and 7c  ii regions of the 7c redshift survey ( 7crs ).   the low  frequency ( 151 mhz ) selected 7crs sample contains all sources with flux - densities @xmath0 jy in three regions of the sky ; 7c  i and 7c  ii were chosen to overlap with the 5c6 and 5c7 surveys respectively, and cover a total sky area of 0.013 sr.   the sample has been completely identified and spectroscopy of the quasars and broad - lined radio galaxies has been presented in willott et al.   ( 1998 ).   only seven of the radio galaxies do not have redshift determinations from the spectroscopy, giving a redshift completeness for the sample of @xmath1%.   the median redshift of the 7crs is 1.1.   we present a composite @xmath2 7crs radio galaxy spectrum and investigate the strengths of the 4000   breaks in these radio galaxies.   we find an anti - correlation between the 4000   break strength and emission line luminosity, indicating that departures from old elliptical galaxy continuum shapes are most likely due to non - stellar emission associated with the active nucleus.   galaxies:@xmath3active  galaxies:@xmath3emission lines  radio continuum:@xmath3galaxies
we study the effects of decoherence on the entanglement generated by unruh effect in noninertial frames by using bit flip, phase damping and depolarizing channels.   it is shown that decoherence strongly influences the initial state entanglement.   the entanglement sudden death can happens irrespective of the acceleration of the noninertial frame under the action of phase flip and phase damping channels.   it is investigated that an early sudden death happens for large acceleration under the depolarizing environment.   moreover, the entanglement increases for a highly decohered phase flip channel.pacs : 03.65.ud ; 03.65.yz ; 03.67.mn;04.70.dy    keywords : entanglement ; decoherence ; noninertial frames.
the style of mathematical models known to probabilists as interacting particle systems and exemplified by the voter, exclusion and contact processes have found use in many academic disciplines. in many such disciplines   the underlying conceptual picture is of a social network, where individuals meet pairwise and update their `` state '' ( opinion, activity etc ) in a way depending on the two previous states.   this picture motivates a precise general setup we call _ finite markov information exchange ( fmie ) processes_. we briefly describe a few less familiar models ( averaging, compulsive gambler, deference, fashionista ) suggested by the social network picture, as well as a few familiar ones.
we present results from an observing campaign of the molecular content of the coma of comet c/1999  s4 ( linear ) carried out jointly with the millimeter - arrays of the berkeley - illinois - maryland association ( bima ) and the owens valley radio observatory ( ovro ).   using the bima array in autocorrelation ( ` single - dish') mode, we detected weak hcn @xmath0=10 emission from comet c/1999  s4 ( linear ) at @xmath1  mk  kms averaged over the @xmath2 beam.   the three days over which emission was detected, 2000 july 21.924.2, immediately precede the reported full breakup of the nucleus of this comet. during this same period,   we find an upper limit for hcn 10 of 144  mjy  beam@xmath3  km  s@xmath3 ( 203  mk  kms ) in the @xmath4 synthesized beam of combined observations of bima and ovro in cross - correlation ( ` imaging') mode. together with reported values of hcn 10 emission in the @xmath5 iram  30-meter beam, our data probe the spatial distribution of the hcn emission from radii of 1300 to 19,000  km. using literature results of hcn excitation in cometary comae  , we find that the relative line fluxes in the @xmath6, @xmath5 and @xmath2 beams are consistent with expectations for a nuclear source of hcn and expansion of the volatile gases and evaporating icy grains following a haser model.
gamma - ray astrophysics depends in many ways on multiwavelength studies.   the gamma - ray large area space telescope ( glast ) large area telescope ( lat ) collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory.   some of the high - priority multiwavelength needs include : ( 1 ) availability of contemporaneous radio and x - ray timing of pulsars ; ( 2 ) expansion of blazar catalogs, including redshift measurements ; ( 3 ) improved observations of molecular clouds, especially at high galactic latitudes ; ( 4 ) simultaneous broad - band blazar monitoring ; ( 5 ) characterization of gamma - ray transients, including gamma ray bursts ; ( 6 ) radio, optical, x - ray and tev counterpart searches for reliable and effective sources identification and characterization.   several of these activities are needed to be in place before launch.
we investigate the interference pattern in the spectrum of non - dipole bremsstrahlung on two amorphous foils.   apart from suppression at lowest @xmath0, the spectrum exhibits an enhancement adjacent to it. in classical electrodynamics, the net effect of suppression and enhancement proves to be zero.   we study the location and the origin of the spectral features, comparing predictions of full molire averaging with those of the gaussian averaging with coulomb corrections to the rms multiple scattering angle.   comparison with experimental data, and with previous theoretical predictions is presented.
cern - th/98 - 401  astro - ph/9902242    the cosmic microwave background ( cmb ) provides a precious window on fundamental physics at very high energy scales, possibly including quantum gravity, guts and supersymmetry.   the cmb has already enabled defect - based rivals to inflation to be discarded, and will be able to falsify many inflationary models. in combination with other cosmological observations, including those of high - redshift supernovae and large - scale structure, the cmb is on the way to providing a detailed budget for the density of the universe, to be compared with particle - physics calculations for neutrinos and cold dark matter.   thus cmb measurements complement experiments with the lhc and long - baseline neutrino beams.
the tumbling of a rigid rod in a shear flow is analyzed in the high viscosity limit.   following burgers, the master equation is derived for the probability distribution of the orientation of the rod.   the equation contains one dimensionless number, the weissenberg number, which is the ratio of the shear rate and the orientational diffusion constant.   the equation is solved for the stationary state distribution for arbitrary weissenberg numbers, in particular for the limit of high weissenberg numbers.   the stationary state gives an interesting flow pattern for the orientation of the rod, showing the interplay between flow due to the driving shear force and diffusion due to the random thermal forces of the fluid.   the average tumbling time and tumbling frequency are calculated as a function of the weissenberg number.   a simple cross - over function is proposed which covers the whole regime from small to large weissenberg numbers.   keywords : shear flow, polymers, fokker - planck equation.
faraday rotation ( fr ) of cmb polarization, as measured through mode - coupling correlations of e and b modes, can be a promising probe of a stochastic primordial magnetic field ( pmf ).   while the existence of a pmf is still hypothetical, there will certainly be a contribution to cmb fr from the magnetic field of the milky way.   we use existing estimates of the milky way rotation measure ( rm ) to forecast its detectability with upcoming and future cmb experiments.   we find that the galactic rm will not be seen in polarization measurements by planck, but that it will need to be accounted for by cmb experiments capable of detecting the weak lensing contribution to the b - mode.   we then discuss prospects for constraining the pmf in the presence of fr due to the galaxy under various assumptions that include partial de - lensing and partial subtraction of the galactic fr.   we find that a realistic future sub - orbital experiment, covering a patch of the sky near the galactic poles, can detect a scale - invariant pmf of 0.1 nano - gauss at better than 95% confidence level, while a dedicated space - based experiment can detect even smaller fields.
a new lattice model of interacting electrons is presented.   it can be viewed as a classical hubbard model in which the energy associated to electron itinerance is proportional to the total number of possible electron jumps.   symmetry properties of the hubbard model are preserved. in the half - filled band with strong interaction   the model becomes the ising model.   the main features of the magnetic behavior of the model in the one - dimensional and mean - field cases are studied.   classical spin model, lattice model, magnetism
the present paper deals with the discrete inverse problem of reconstructing binary matrices from their row and column sums under additional constraints on the number and pattern of entries in specified minors.   while the classical consistency and reconstruction problems for two directions in discrete tomography can be solved in polynomial time, it turns out that these window constraints cause various unexpected complexity jumps back and forth from polynomial - time solvability to @xmath0-hardness.   = 1
we present the distribution map of the far - infrared   88 line emission around the 30 doradus ( 30 dor ) region in the large magellanic cloud obtained with the fourier transform spectrometer of the far - infrared surveyor onboard akari.   the map reveals that the  emission is widely distributed by more than @xmath0 around the super star cluster r136, implying that the 30 dor region is affluent with interstellar radiation field hard enough to ionize o@xmath1.   the observed  line intensities are as high as @xmath2 w m@xmath3 sr@xmath4 on the peripheral regions @xmath5 away from the center of 30 dor, which requires gas densities of @xmath6 @xmath7.   however the observed size of the distribution of the  emission is too large to be explained by massive stars in the 30 dor region enshrouded by clouds with the constant gas density of @xmath8 @xmath7.   therefore the surrounding structure is likely to be highly clumpy.   we also find a global correlation between the  and the far - infrared continuum emission, suggesting that the gas and dust are well mixed in the highly - ionized region where the dust survives in clumpy dense clouds shielded from the energetic photons.
we study theoretically the interaction between soft magnetic and superconducting films.   it is shown that the vortex induces a magnetization distribution in the magnetic film, thus modifying the magnetic field as well as the interactions with e.g. bloch walls.   in particular, the field from the vortex may change sign close to the core as a result of the vortex - induced magnetization, thus resulting in a crossover from attraction to repulsion between vortices and bloch walls.   moreover, we show that by tuning the anisotropy field of the magnetic film, one may enhance the interaction between bloch walls and vortices.   finally, we discuss how the structure of a bloch wall in presence of the thin film superconductor can be revealed by magneto - optic imaging using an additional magneto - optic indicator.
we have presented a theoretical study of electrorotation assay based on the spectral representation theory.   we consider unshelled and shelled spheroidal particles as an extension to spherical ones. from the theoretical analysis, we find that the coating can change the characteristic frequency at which the maximum rotational angular velocity occurs.   the shift in the characteristic frequency is attributed to a change in the dielectric properties of the bead - coating complex with respect to those of the unshelled particles. by adjusting the dielectric properties and the thickness of the coating  , it is possible to obtain good agreement between our theoretical predictions and the assay data.
we show that the fulde - ferrell ( ff ) phase may appear as a sole result of the orbital effect in a cylindrical metallic nanowire.   namely, in the external magnetic field the two - fold degeneracy with respect to the orbital magnetic quantum number @xmath0 is lifted, what leads to a fermi wave vector mismatch between the subbands with opposite orbital momenta in the paired state.   this mismatch can be compensated by the nonzero total momentum of the cooper pairs created by electrons from the split subbands what results in the formation of the ff phase. in this manner, a transformation of the orbital motion into a linear supercurrent parallel to the applied field is taking place. with the increasing magnetic field a series of ff stability regions appear, in between which the standard bcs superconducting phase is stable. for the sake of completness, we show, that the inclusion of the zeeman term in the model does not change the picture qualitatively, particularly if larger @xmath0 states contribute essentially to the fermi - surface splitting. a brief but important note concerning the possibility of steering the supercurrent by an applied magnetic field parallel to it, is also provided.
we review c - field methods for simulating the non - equilibrium dynamics of degenerate bose gases beyond the mean - field gross  pitaevskii approximation.   we describe three separate approaches that utilise similar numerical methods, but have distinct regimes of validity.   systems at finite temperature can be treated with either the closed - system projected gross  pitaevskii equation ( pgpe ), or the open - system stochastic projected gross  pitaevskii equation ( spgpe ).   these are both applicable in quantum degenerate regimes in which thermal fluctuations are significant. at low or zero temperature,   the truncated wigner projected gross  pitaevskii equation ( twpgpe ) allows for the simulation of systems in which spontaneous collision processes seeded by quantum fluctuations are important.   we describe the regimes of validity of each of these methods, and discuss their relationships to one another, and to other simulation techniques for the dynamics of bose gases.   the utility of the spgpe formalism in modelling non - equilibrium bose gases is illustrated by its application to the dynamics of spontaneous vortex formation in the growth of a bose   einstein condensate.
we present the results of an observation of the radio - quiet x  ray pulsar  located at the center of the shell - like supernova remnant .   the x  ray spectrum is characterized by the presence of two phase - dependent absorption lines at energies @xmath00.7 kev and @xmath01.4 kev.   moreover, these broad spectral features have significant substructure, suggesting that they are due to the blending of several narrower lines.   we interpret such features as evidence for an atmosphere containing metals and a magnetic field value of a few 10@xmath1 g, consistent with the observed spin - down rate @xmath2=(1.98@xmath30.83)@xmath410@xmath5 s s@xmath6. since  is the only x  ray emitting pulsar showing evidence of such features, we tentatively link them to the unique combination of age and energetics that characterize this object.   we suggest that a young age and a low level of magnetospheric activity are favorable conditions for the detection of atomic spectral features from @xmath7 elements in neutron star atmospheres, which would be either blanketed by a thin layer of accreted hydrogen in older objects or masked by non - thermal processes in young energetic pulsars.
the crab nebula has proved to be the nearest to a standard candle in vhe @xmath0 ray astronomy.   results on the gamma ray emission from the nebula at various energies have come in the last decade mostly from imaging telescopes.   the aim of the new pachmarhi atmospheric cerenkov telescope ( pact ) array has been to use the temporal and spatial distribution of cerenkov photons in distinguishing between proton and gamma ray showers.   the array, with timing information from 175 mirrors, is ideally suited for precise estimation of the arrival direction.   preliminary results from the recent data taken on crab has shown a 12@xmath1 signal with the flux in good agreement with those of the other experiments.
collaborative beamforming enables nodes in a wireless network to transmit a common message over long distances in an energy efficient fashion.   however, the process of making available the same message to all collaborating nodes introduces delays.   the authors recently proposed a mac - phy cross - layer scheme that enables collaborative beamforming with significantly reduced collaboration overhead.   the method requires knowledge of node locations and internode channel coefficients. in this paper  , the performance of that approach is studied analytically in terms of average beampattern and symbol error probability ( sep ) under realistic conditions, i.e., when imperfect channel estimates are used and when there are phase errors in the contributions of the collaborating nodes at the receiver.   collaborative beamforming, cross - layer approach for wireless networks, imperfect conditions
we discuss recent results obtained by the authors in  @xcite, regarding the analysis of the magneto - geostrophic equation : a model proposed by moffatt and loper  @xcite to study the geodynamo and turbulence in the earth s fluid core.   we conclude this review by indicating some open problems around the mg equation, that remain to be addressed in the future.
we consider the problem of the gravitational waves produced by a particle of negligible mass orbiting a kerr black hole.   we treat the teukolsky perturbation equation in the time domain numerically as a 2 + 1 partial differential equation.   we model the particle by smearing the singularities in the source term by the use of narrow gaussian distributions.   we have been able to reproduce earlier results for equatorial circular orbits that were computed using the frequency domain formalism.   the time domain approach is however geared for a more general evolution, for instance of nearly geodesic orbits under the effects of radiation reaction.
the near threshold expansion of generalized sunset - type ( water melon ) diagrams with arbitrary masses is constructed by using a configuration space technique.   we present analytical expressions for the expansion of the spectral density near threshold and compare it with the exact expression obtained earlier using the method of the hankel transform.   we formulate a generalized threshold expansion with partial resummation of the small mass corrections for the strongly asymmetric case where one particle in the intermediate state is much lighter than the others.   mz - th/00 - 07 + hep - ph/0003115 + march 2000     * threshold expansion of feynman diagrams + within a configuration space technique * + s.  groote@xmath0 and a.a.   pivovarov@xmath1 + @xmath0 institut fr physik, johannes - gutenberg - universitt, + staudinger weg 7, d-55099 mainz, germany + @xmath2 institute for nuclear research of the + russian academy of sciences, moscow 117312
we study the behaviour of five - dimensional fermions localized on branes, which we describe by domain walls, when two parallel branes collide in a five - dimensional minkowski background spacetime.   we find that most fermions are localized on both branes as a whole even after collision.   however, how much fermions are localized on which brane depends sensitively on the incident velocity and the coupling constants unless the fermions exist on both branes.
recent observations with the hubble space telescope ( hst ) have revealed that a large fraction of late - type ( sc and later ) spiral galaxies harbor a bright, compact stellar cluster in their dynamical centers.   statistics of the mass, age, and star formation history of these clusters as a function of their host galaxy s hubble type can be used to constrain models of secular galaxy evolution. since late - type spirals by definition   do not possess a prominent bulge, their nuclear clusters are more easily separated from the underlying disk population.   their spectroscopic properties can thus be studied from ground - based observations. here  , i will discuss plans for, and first results of, a program to study a sample of known nuclear clusters in late - type spirals. for one galaxy ( ic  342 ),   we have used high - resolution near infrared spectroscopy to determine the cluster mass directly via its stellar velocity dispersion.   the analysis conclusively shows a very low mass - to - light ratio for the nuclear cluster in, indicative of a young cluster age ( @xmath0 50  myrs ). from probability arguments  , this result favors the scenario that such bursts are a recurrent phenomenon in late - type spiral nuclei.
we study the decorrelation in azimuthal angle of mueller  navelet jets at hadron colliders within the bfkl formalism.   we introduce nlo terms in the evolution kernel and present a collinearly  improved version of it for all conformal spins.   we show how this further resummation has good convergence properties and is closer to the tevatron data than a simple lo treatment  . however, we are still far from a good fit.   we offer estimates of these decorrelations for larger rapidity differences which should favor the onset of bfkl effects and encourage experimental studies of this observable at the lhc.    cern  ph   th/2007029 + desy07017
motivated by the energy representation of riemannian metric, in this paper we study different approaches toward the geometrical concept of black hole thermodynamics.   we investigate thermodynamical ricci scalar of weinhold, ruppeiner and quevedo metrics and show that their number and location of divergences do not coincide with phase transition points arisen from heat capacity.   next, we introduce a new metric to solve these problems.   we show that the denominator of the ricci scalar of the new metric contains terms which coincide with different types of phase transitions.   we elaborate the effectiveness of the new metric and shortcomings of the previous metrics with some examples.   furthermore, we find a characteristic behavior of the new thermodynamical ricci scalar which enables one to distinguish two types of phase transitions.   in addition, we generalize the new metric for the cases of more than two extensive parameters and show that in these cases the divergencies of thermodynamical ricci scalar coincide with phase transition points of the heat capacity.
we investigate the possibility that freely rotating cylinders with an aspect ratio @xmath0 exhibit a cubatic phase similar to the one found for a system of cut - spheres.   we present theoretical arguments why a cubatic phase might occur in this particular system.   monte carlo simulations do not confirm the existence of a cubatic phase for cylinders.   however, they do reveal an unexpected phase behavior between the isotropic and crystalline phase.
in order to describe properties of an equilibrated quark - gluon plasma, qcd at finite temperature ( and density ) has to be considered. besides lattice calculations, which can be applied only to static quantities at zero density, perturbative   qcd has been used. at finite temperature, however, serious problems such as infrared divergent and gauge dependent results have been encountered.   these difficulties can be ( partially ) avoided if one starts from effective green functions constructed by resumming a certain class of diagrams ( hard thermal loops ). within the last few years this improved perturbation theory ( braaten - pisarski method ) turned out to be a powerful tool for computing interesting quantities of the quark - gluon plasma phase.    in the present talk a basic introduction to the braaten - pisarski method   is provided and its applications and limits are reviewed.   in particular, damping rates, the energy loss of energetic partons, thermalization times, the viscosity of the quark - gluon plasma, and the production of photons and dileptons are discussed.
we analyze the effect of color superconductivity in the transition from hot hadron matter to quark matter in the presence of a gas of trapped electron neutrinos. to describe strongly interacting matter   we adopt a two - phase picture in which the hadronic phase is described by means of a non - linear walecka model and just deconfined matter through the mit bag model including color superconductivity.   we impose flavor conservation during the transition in such a way that just deconfined quark matter is transitorily out of equilibrium with respect to weak interactions.   our results show that color superconductivity facilitates the transition for temperatures below @xmath0  . this effect may be strong if the superconducting gap is large enough.   as in previous work we find that trapped neutrinos increase the critical density for deconfinement ; however, if the just deconfined phase is color superconducting this effect is weaker than if deconfined matter is unpaired.   we also explore the effect of different parametrizations of the hadronic equation of state ( gm1 and nl3 ) and the effect of hyperons in the hadronic phase.   we compare our results with those previously obtained employing the nambu - jona - lasinio model in the description of just deconfined matter and show that they are in excellent agreement if the bag constant @xmath1 is properly chosen.   phase transition, quark matter, color superconductivity, protoneutron stars
information - theoretic work for wiretap channels is mostly based on random coding schemes. designing practical coding schemes to achieve information - theoretic security   is an important problem. by applying the two recently developed techniques for polar codes,   we propose a polar coding scheme to achieve the secrecy capacity of the general wiretap channel.
the singlet - triplet relaxation in nanowire - based quantum dots induced by confined phonons is investigated theoretically. due to the quasi - one - dimensional nature of the confined phonons, the singlet - triplet relaxation rates exhibit multi - peaks as function of magnetic field and the relaxation rate between the singlet and the spin up triplet state   is found to be enhanced at the vicinity of the singlet - triplet anti - crossing.   we compare the effect of the deformation - potential coupling and the piezoelectric coupling and find that the deformation - potential coupling dominates the relaxation rates in most cases.
katz and vafa @xcite showed how charged matter can arise geometrically by the deformation of ade - type orbifold singularities in type iia, m - theory, and f - theory compactifications. in this paper   we use those same basic ingredients, used there to geometrically engineer specific matter representations, here to deform the compactification manifold itself in a way which naturally compliments many features of unified model building.   we realize this idea explicitly by deforming a manifold engineered to give rise to an @xmath0 grand unified model into a one giving rise to the standard model. in this framework,   the relative local positions of the singularities giving rise to standard model fields are specified in terms of the values of a small number of complex structure moduli which deform the original manifold, greatly reducing the arbitrariness of their relative positions.
following novel development and adaptation of the metric space technique ( mst ), a multi - scale morphological analysis of the sloan digital sky survey ( sdss ) data release 5 ( dr5 ) was performed.   the technique was adapted to perform a space - scale morphological analysis by filtering the galaxy point distributions with a smoothing gaussian function, thus giving quantitative structural information on all size scales between 5 and 250 mpc.   the analysis was performed on a dozen slices of a volume of space containing many newly measured galaxies from the sdss dr5 survey. using the mst,   observational data were compared to galaxy samples taken from _   n_-body simulations with current best estimates of cosmological parameters and from random catalogs. by using the maximal ranking method among mst output functions   we also develop a way to quantify the overall similarity of the observed samples with the simulated samples.
quasiparticles in semiconductors  such as microcavity polaritons  can form condensates in which the steady - state density profile is set by the balance of pumping and decay. by taking account of the polarization degree of freedom for a polariton condensate, and considering the effects of an applied magnetic field  , we theoretically discuss the interplay between polarization dynamics, and the spatial structure of the pumped decaying condensate.   if spatial structure is neglected, this dynamics has attractors that are linearly polarized condensates ( fixed points ), and desynchronized solutions ( limit cycles ), with a range of bistability. considering spatial fluctuations about the fixed point, the collective spin modes can either be diffusive, linearly dispersing, or gapped. including spatial structure, interactions between the spin components can influence the dynamics of vortices ; produce stable complexes of vortices and rarefaction pulses with both co- and counter - rotating polarizations ; and increase the range of possible limit cycles for the polarization dynamics, with different attractors displaying different spatial structures.
the silicon detectors used in the h1-plug calorimeter have shown increasing aging effects during the 94 run period of the electron proton storage ring hera.   these effects were particularly manifest as degradation of the signal to noise level and the calibration stability.   the reasons for this behaviour have been found to be correlated with radiation damage to the silicon oxide passivation edges of the detectors in strong and fluctuating increases of the leakage currents and in severe changes of the flat band voltages.   depletion voltages however are found to be stable and therefore bulk damage of the silicon can be excluded.   a comparison with measurements made by thermoluminescence dosimeters as well as related laboratory experiments suggest that the aging is due to very low energetic electrons and photons.   an investigation into the radiation damage + of the silicon detectors of the h1-plug calorimeter + within the hera environment    w. hildesheim, m. seidel
it has been shown that there are not only transverse but also longitudinal couplings between microwave fields and a superconducting qubit with broken inversion symmetry of the potential energy.   using multiphoton processes induced by longitudinal coupling fields and frequency matching conditions, we design a universal algorithm to produce arbitrary superpositions of two - mode photon states of microwave fields in two separated transmission line resonators, which are coupled to a superconducting qubit. based on our algorithm, we analyze the generation of evenly - populated states and noon states. compared to other proposals with only single - photon process  , we provide an efficient way to produce entangled microwave states when the interactions between superconducting qubits and microwave fields are in the ultrastrong regime.
we consider the bremsstrahlung surface photon emissivity of strange quark stars, by sistematically taking into account the effects of the multiple scatterings of the highly relativistic quarks in a dense medium ( the landau - pomeranchuk - migdal effect ). due to interference between amplitudes of nearby interactions the bremsstrahlung emissivity from strange star surface   is suppressed for frequencies smaller than a critical frequency.   the range of the suppressed frequencies is a function of the quark matter density at the star s surface and of the qcd coupling constant. for temperatures much smaller than the fermi energy of the quarks   the bremsstrahlung spectrum has the same temperature dependence as the equilibrium black body radiation.   multiple collisions could reduce by an order of magnitude the intensity of the bremsstrahlung radiation.   the effect of the thin electron layer at the surface of the quark star on the bremsstrahlung spectrum is also analyzed in detail.   it is shown that absorption in the semi - degenerate electron gas can also significantly reduce the intensity of the quark - quark bremsstrahlung radiation and, consequently, the surface emissivity.   hence the combined effects of multiple collisions and absorption in the electron layer could make the soft photon surface radiation of quark stars six orders of magnitude smaller than the equilibrium black body radiation.
fully sampled degree - scale maps of the @xmath0co 21 and co 43 transitions toward three members of the lupus molecular cloud complex  lupus  i, iii, and iv  trace the column density and temperature of the molecular gas.   comparison with ir extinction maps from the c2d project requires most of the gas to have a temperature of 810k.   estimates of the cloud mass from @xmath0co emission are roughly consistent with most previous estimates, while the line widths are higher, around 2  kms@xmath1.   co 43 emission is found throughout lupus  i, indicating widespread dense gas, and toward lupus  iii and iv.   enhanced line widths at the nw end and along the edge of the b228 ridge in lupus  i, and a coherent velocity gradient across the ridge, are consistent with interaction between the molecular cloud and an expanding shell from the upper - scorpius subgroup of the sco - cen ob association.   lupus  iii is dominated by the effects of two hae / be stars, and shows no sign of external influence.   slightly warmer gas around the core of lupus  iv and a low line width suggest heating by the upper - centaurus - lupus subgroup of sco - cen, without the effects of an shell.
we analyze possible nonlinear exciton - exciton correlation effects in the optical response of semiconductors by using a time - dependent density - functional theory ( tddft ) approach. for this purpose  , we derive the nonlinear ( third - order ) tddft equation for the excitonic polarization. in this equation,   the nonlinear time - dependent effects are described by the time - dependent ( non - adiabatic ) part of the effective exciton - exciton interaction, which depends on the exchange - correlation ( xc ) kernel.   we apply the approach to study the nonlinear optical response of a gaas quantum well. in particular, we calculate the 2d fourier spectra of the system and compare it with experimental data.   we find that the memory effects play a crucial role in this response, and in particular that it is necessary to use a non - adiabatic xc kernel to describe excitonic bound states - biexcitons, which are formed due to the retarded tddft exciton - exciton interaction.   ,
computational models of complex systems are usually elaborate and sensitive to implementation details, characteristics which often affect their verification and validation.   model replication is a possible solution to this issue.   it avoids biases associated with the language or toolkit used to develop the original model, not only promoting its verification and validation, but also fostering the credibility of the underlying conceptual model.   however, different model implementations must be compared to assess their equivalence.   the problem is, given two or more implementations of a stochastic model, how to prove that they display similar behavior?   in this paper, we present a model comparison technique, which uses principal component analysis to convert simulation output into a set of linearly uncorrelated statistical measures, analyzable in a consistent, model - independent fashion.   it is appropriate for ascertaining distributional equivalence of a model replication with its original implementation. besides model - independence, this technique has three other desirable properties : a ) it automatically selects output features that best explain implementation differences ; b ) it does not depend on the distributional properties of simulation output ; and, c ) it simplifies the modelers work, as it can be used directly on simulation outputs.   the proposed technique is shown to produce similar results to classic comparison methods when applied to a well - studied reference model.   = 1    * _ keywords _ * model alignment ; docking ; pca ; model replication ; simulation output analysis
we present a generalization of the often - used crank - nicolson ( cn ) method of obtaining numerical solutions of the time - dependent schrdinger equation.   the generalization yields numerical solutions accurate to order @xmath0 in space and @xmath1 in time for any positive integers @xmath2 and @xmath3, while cn employ @xmath4.   we note dramatic improvement in the attainable precision ( circa 10 or greater orders of magnitude ) along with several orders of magnitude reduction of computational time. the improved method is shown to lead to feasible studies of coherent - state oscillations with additional short - range interactions, wavepacket scattering, and long - time studies of decaying systems.
we study the dissipative dynamics of a biased two - level system ( tls ) coupled to a harmonic oscillator ( ho ), the latter interacting with an ohmic environment. using van - vleck perturbation theory and going to second order in the coupling between tls and   ho, we show how the hamiltonian of the tls - ho system can be diagonalized analytically.   our model represents an improvement to the usually used jaynes - cummings hamiltonian as an initial rotating wave approximation is avoided. by assuming a weak coupling to the thermal bath  , analytical expressions for the time evolution of the populations of the tls are found : the population is characterized by a multiplicity of damped oscillations together with a complex relaxation dynamics towards thermal equilibrium.   the long time evolution is characterized by a single relaxation rate, which is largest at resonance and whose expression can be given in closed analytic form.   _ keywords _ : quantum dissipation, quantum computation
in this paper we present the elementary assumptions of our research on the role of the magnetic field in modelling the quiescence - outbursts cycle in cataclysmic variables ( cvs ).   the behaviour of the magnetic field is crucial not only to integrate the disk instability model ( osaki 1974 ), but also to determine the cause and effect nexus among parameters affecting the behavior of complex systems. on the ground of our interpretation of the results emerging from the literature, we suggest that in models describing dne outbursts, such as the disk instability model, the secondary instability model ( bath 1973 ) and the thermonuclear runaway model ( mitrofanov 1978 ), the role of the magnetic field is at least twofold. on the one hand, it activates a specific dynamic pathway for the accreting matter by channelling it. on the other hand, it could be indirectly responsible for switching a particular outburst modality. in order to represent these two roles of the magnetic field, we need to integrate the disk instability model by looking at the global behaviour of the system under analysis.   stochastic resonance in dynamo models, we believe, is a suitable candidate for accomplishing this task.   we shall present the mhd model including this mechanism elsewhere.    2
a model is proposed to explain temporal patterns of activity in a class of periodically exploding strombolian - type volcanos.   these patterns include major events ( explosions ) which follow each other every 10 - 30 minutes and subsequent tremor with a typical period of 1 second.   this two - periodic activity is thought to be caused by two distinct mechanisms of accumulation of the elastic energy in the moving magma column : compressibility of the magma in the lower conduit and viscoelastic response of the almost solid magma plug on the top.   a release of the elastic energy happens when a stick - slip dynamic phase transition in a boundary layer along the walls of the conduit occurs ; this phase transition is driven by the shear stress accumulated in the boundary layer.   the first - order character and intrinsic hysteresis of this phase transition explains the long periods of inactivity in the explosion cycle.   temporal characteristics of the model are found to be qualitatively similar to the acoustic and seismic signals recorded at karymsky volcano in kamchatka.   keywords : stick - slip phase transition, viscoelasticity, hysteresis.   _ _ slip   _
the opacity - modified eddington limit has been computed for hydrogen - deficient model atmospheres. the r coronae borealis ( rcrb ) stars are found to be located strikingly close to the limit, which suggests that the unknown trigger mechanism for their visual declines of the stars are instabilities in connection with the stars encountering the eddington limit in their evolution  . it also points to a similarity between the eruptive behaviour of the rcrb stars and the luminous blue variables ( lbvs ).   super - eddington luminosities in hydrostatic model atmospheres manifest themselves by the presence of gas pressure inversions.   such inversions are not an artifact of the assumption of hydrostatic equilibrium but can also be present in hydrodynamical model atmospheres. only for very large mass loss rates   hardly realized in supergiants will the inversions be removed.   instabilities may, however, still be present in such inversions, which is investigated for both h - rich and h - deficient late - type supergiant model atmospheres.   dynamical instabilities may occur in surface ionization zones, which might lead to ejections of gas.   a local, non - adiabatic, linear stability analysis reveals that sound waves can be amplified due to the strong radiative forces.   however, despite the super - eddington luminosities, the efficiency of the radiative instabilities is fairly low compared to for early - type stars with growth rates of @xmath0s@xmath1.
when a plane shock hits a wedge head on, it experiences a reflection - diffraction process, and then a self - similar reflected shock moves outward as the original shock moves forward in time.   the complexity of reflection - diffraction configurations was first reported by ernst mach in 1878, and experimental, computational, and asymptotic analysis has shown that various patterns of shock reflection - diffraction configurations may occur, including regular reflection and mach reflection. in this paper   we start with various shock reflection - diffraction phenomena, their fundamental scientific issues, and their theoretical roles as building blocks and asymptotic attractors of general solutions in the mathematical theory of multidimensional hyperbolic systems of conservation laws.   then we describe how the global problem of shock reflection - diffraction by a wedge can be formulated as a free boundary problem for nonlinear conservation laws of mixed - composite hyperbolic - elliptic type.   finally we discuss some recent developments in attacking the shock reflection - diffraction problem, including the existence, stability, and regularity of global regular reflection - diffraction solutions.   the approach includes techniques to handle free boundary problems, degenerate elliptic equations, and corner singularities, which is highly motivated by experimental, computational, and asymptotic results. further trends and open problems in this direction are also addressed.
we study the pion leading - twist distribution amplitude ( da ) within the framework of svz sum rules under the background field theory. to improve the accuracy of the sum rules,   we expand both the quark propagator and the vertex @xmath0 of the correlator up to dimension - six operators in the background field theory.   the sum rules for the pion da moments are obtained, in which all condensates up to dimension - six have been taken into consideration. using the sum rules, we obtain @xmath1, @xmath2 and @xmath3. it is shown that the dimension - six condensates shall provide sizable contributions to the pion da moments.   we show that the first gegenbauer moment of the pion leading - twist da is @xmath4, which is consistent with those obtained in the literature within errors but prefers a larger central value as indicated by lattice qcd predictions.
in this paper we present the experimental realization of a nb tunnel junction connected to a high - gap superconducting nbtin embedding circuit. we investigate relaxation of nonequilibrium quasiparticles in a small volume au layer between the nb tunnel junction and the nbtin circuit.   we find a saturation in the effective heat - transfer coefficient consistent with a simple theoretical model.   this saturation is determined by the thickness of the au layer.   our findings are important for the design of the ideal au energy relaxation layer for practical sis heterodyne mixers and we suggest two geometries, one, using a circular au layer and, two, using a half - circular au layer. our work is concluded with an outlook of our future experiments.    4epo2e-07    heat transfer, niobium sis junctions, nonequilibrium, sis mixers, superconductivity.
certain methods of analysis require the knowledge of the spatial distances between entities whose data are stored in a microdata table.   for instance, such knowledge is necessary and sufficient to perform data mining tasks such as nearest neighbour searches or clustering.   however, when inter - record distances are published in addition to the microdata for research purposes, the risk of identity disclosure has to be taken into consideration again. in order to tackle this problem, we introduce a flexible graph model for microdata in a metric space and propose a linkage attack based on realistic assumptions of a data snooper s background knowledge.   this attack is based on the idea of finding a maximum approximate common subgraph of two vertex - labelled and edge - weighted graphs. by adapting a standard argument from algorithmic graph theory to our setup,   this task is transformed to the maximum clique detection problem in a corresponding product graph. using a toy example and experimental results on simulated data   show that publishing even approximate distances could increase the risk of identity disclosure unreasonably.   _ keywords _ : anonymity, identity disclosure, linkage attack, maximum approximate common subgraph problem
in this paper we construct asymptotically locally ads and flat black holes in the presence of a scalar field whose kinetic term is constructed out from a linear combination of the metric and the einstein tensor.   the field equations as well as the energy - momentum tensor are second order in the metric and the field, therefore the theory belongs to the ones defined by horndeski.   we show that in the presence of a cosmological term in the action, it is possible to have a real scalar field in the region outside the event horizon.   the solutions are characterized by a single integration constant, the scalar field vanishes at the horizon and it contributes to the effective cosmological constant at infinity.   we extend these results to the topological case.   the solution is disconnected from the maximally symmetric ads background, however, within this family there exits a gravitational soliton which is everywhere regular.   this soliton is therefore used as a background to define a finite euclidean action and to obtain the thermodynamics of the black holes. for a certain region in the space of parameters, the thermodynamic analysis reveals a critical temperature at which a hawking - page phase transition between the black hole and the soliton occurs.   we extend the solution to arbitrary dimensions grater than four and show that the presence of a cosmological term in the action allows to consider the case in which the standard kinetic term for the scalar it s not present. in such scenario, the solution reduces to an asymptotically flat black hole.
we have examined a probable soft x - ray transient source in the m31 bulge at r.a.=0:42:41.814 @xmath0 0.08@xmath1, dec.   = 41:16:35.86 @xmath0 0.07@xmath1. on the three occasions   we observed the source, its spectrum was soft ( @xmath2 kev ).   the brightest detection of the source was 2004  july  17 with a 0.37 kev luminosity of @xmath35@xmath4 erg s@xmath5.   the only previous detection of the source was in 1979 by the _ einstein _ observatory.   the multiple detections over 25 years suggest the duty cycle of the source is in the range 0.020.06. coordinated _ hst _   acs imaging before, during, and after the outburst revealed no variable optical source within the position errors of the x - ray source.   the optical data place a firm upper limit on the brightness of the counterpart of the x - ray outburst of @xmath6, suggesting the binary has a period @xmath7 days. the x - ray spectrum and lack of bright stars at the source location indicate the source was a soft transient event occurring in a low - mass x - ray binary, making this source a good black hole candidate in m31.
we investigate the influence of photoevaporation of protoplanetary discs on the final distribution of exoplanets semi - major axis distances.   we model giant planet migration in viscous discs affected by photoevaporation driven by either pure euv or soft x - ray radiation ( xeuv ).   we show that the final exoplanet distributions are strongly dependant on the choice of the photoevaporation model.   in particular, we find that xeuv is more efficient than pure euv radiation at parking planets at approximately 1 - 2 au distance from their central star, hence roughly reproducing the observed peak in the exoplanets semi - major axis distributions.   we note however that a more quantitative comparison with the observations is hindered by the oversimplified treatment of planetary accretion, which severely affects migration rates. for this reason  , caution should be used when using these models to constrain details of disc clearing and/or migration from the observations.   nevertheless our results indicate that disc dispersal by photoevaporation may be the main driver of the features in the exoplanets semi - major axis distribution observed by recent surveys.       -.4 in    planet - disc interactions
we perform a global parton analysis of deep inelastic and related hard - scattering data, including @xmath0 corrections to the parton evolution.   although the quality of the fit is essentially unchanged, there are two important physical consequences.   first, the different dglap evolution of @xmath1 and @xmath2 type quarks introduces isospin violation, i.e. @xmath3, which is found to be unambiguously in the direction to reduce the nutev @xmath4 anomaly.   a second consequence is the appearance of photon parton distributions @xmath5 of the proton and the neutron. in principle   these can be measured at hera via the deep inelastic scattering processes @xmath6 ; our predictions are in agreement with the present data.   plus 2 mm minus 2 mm 23.0 cm 17.0 cm -1.0 in -42pt    ippp/04/62 + dcpt/04/124 + cavendish - hep-2004/28 + 2nd november 2004 +    * parton distributions incorporating qed contributions *    a.d.   martin@xmath7, r.g.   roberts@xmath8, w.j. stirling@xmath7 and r.s.   thorne@xmath9 + @xmath7 institute for particle physics phenomenology, university of durham, dh1 3le, uk + @xmath8 rutherford appleton laboratory, chilton, didcot, oxon, ox11 0qx, uk + @xmath10 cavendish laboratory, university of cambridge, + madingley road, cambridge, cb3 0he, uk
recent theoretical and empirical work in statistical machine learning has demonstrated the importance of learning algorithms for deep architectures, i.e., function classes obtained by composing multiple non - linear transformations.   self - taught learning ( exploiting unlabeled examples or examples from other distributions ) has already been applied to deep learners, but mostly to show the advantage of unlabeled examples. here   we explore the advantage brought by _ out - of - distribution examples_. for this purpose we developed a powerful generator of stochastic variations and noise processes for character images, including not only affine transformations but also slant, local elastic deformations, changes in thickness, background images, grey level changes, contrast, occlusion, and various types of noise.   the out - of - distribution examples are obtained from these highly distorted images or by including examples of object classes different from those in the target test set.   we show that _ deep learners benefit more from out - of - distribution examples than a corresponding shallow learner _, at least in the area of handwritten character recognition.   in fact, we show that they beat previously published results and reach human - level performance on both handwritten digit classification and 62-class handwritten character recognition.
we report the detection of off - pulse emission from two long period pulsars psr b0525 + 21 & psr b204516 using the giant metrewave radio telescope ( gmrt ).   we recorded high time resolution interferometric data at 325 mhz and gated the data offline to separate the on- and off - pulse sections of the pulsar. on imaging the two temporal sections separately  , we detected a point source in the off - pulse images of both the pulsars coincident with the pulsar locations in the on - pulse images.   the long periods ( 3.75 and 1.96 s respectively ) and low spin - down energies ( @xmath0 erg  s@xmath1 ) of the two pulsars argue against a pulsar wind nebula ( pwn ) origin for the off - pulse emission.   the derived estimates of the ism particle density required to drive a pwn do not support such an interpretation.   a magnetospheric origin for the off - pulse emission raises questions regarding the location of the emission region, which is an important input into pulsar emission models.
we construct finite volume hyperbolic manifolds with large symmetry groups.   the construction makes use of the presentations of finite coxeter groups provided by barot and marsh and involves mutations of quivers and diagrams defined in the theory of cluster algebras.   we generalize our construction by assigning to every quiver or diagram of finite or affine type a cw - complex with a proper action of a finite ( or affine ) coxeter group.   these cw - complexes undergo mutations agreeing with mutations of quivers and diagrams.   we also generalize the construction to quivers and diagrams originating from unpunctured surfaces and orbifolds.
the empirical valence bond ( evb ) method [ j.  chem.   phys.  * 52 *, 1262 ( 1970 ) ] has always embodied charge transfer processes.   the mechanism of that behavior is examined here and recast for use as a new empirical potential energy surface for large - scale simulations.   a two - state model is explored.   the main features of the model are : ( 1 ) explicit decomposition of the total system electron density is invoked ; ( 2 ) the charge is defined through the density decomposition into constituent contributions ; ( 3 ) the charge transfer behavior is controlled through the resonance energy matrix elements which can not be ignored ; and ( 4 ) a reference - state approach, similar in spirit to the evb method, is used to define the resonance state energy contributions in terms of `` knowable '' quantities. with equal validity, the new potential energy can be expressed as a _   nonthermal _ ensemble average with a nonlinear but analytical charge dependence in the occupation number.   dissociation to neutral species for a gas - phase process is preserved.   a variant of constrained search density functional theory is advocated as the preferred way to define an energy for a given charge.
evolution of perturbed embedded solitons in the general hamiltonian fifth - order korteweg  de vries ( kdv ) equation is studied. when an embedded soliton is perturbed, it sheds a one - directional continuous - wave radiation.   it is shown that the radiation amplitude is not minimal in general.   a dynamical equation for velocity of the perturbed embedded soliton is derived.   this equation shows that a neutrally stable embedded soliton is in fact semi - stable.   when the perturbation increases the momentum of the embedded soliton, the perturbed state approaches asymptotically the embedded soliton, while when the perturbation reduces the momentum of the embedded soliton, the perturbed state decays into radiation.   classes of initial conditions to induce soliton decay or persistence are also determined.   our analytical results are confirmed by direct numerical simulations of the fifth - order kdv equation.   addtoreset equationsection
in these lectures, we present and discuss the most recent results on inclusive diffraction from the hera and tevatron colliders and give the prospects for the future at the lhc. of special interest   is the exclusive production of higgs boson and heavy objects ( @xmath0, top, stop pairs ) which will require a better understanding of diffractive events and the link between @xmath1 and hadronic colliders, as well as precise measurements and analyses of inclusive diffraction at the lhc in particular to constrain further the gluon density in the pomeron.    in these lectures  , we describe the most recent results on inclusive diffraction at hera, as well as diffractive results from the tevatron.   we finish the lecture by discussing the prospects of diffractive physics at the lhc.
we present results of timing observations of the 143-ms pulsar j0538 + 2817 that provide a proper motion measurement which clearly associates the pulsar with the supernova remnant s147.   we measure a proper motion of 67@xmath0 mas yr@xmath1, implying a transverse velocity of @xmath2 km s@xmath1.   we derive an age of the pulsar and s147 of only @xmath3 kyr which is a factor of 20 times less than the pulsar s characteristic age of @xmath4 kyr.   this age implies an initial spin period of @xmath5 ms, close to the present pulse period and a factor of several larger than what is usually inferred for birth periods.   implications for recent x - ray detections of this pulsar are discussed.
the capture and disruption of stars by supermassive black holes ( smbhs ), and the formation and coalescence of binaries, are inevitable consequences of the presence of smbhs at the cores of galaxies.   pairs of active galactic nuclei ( agn ) and binary smbhs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. in the early and advanced stages of   galaxy merging, observations of the triggering of accretion onto one or both bhs inform us about feedback processes and bh growth.   identification of the compact binary smbhs at parsec and sub - parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the `` final parsec ''. coalescing binary smbhs   are among the most powerful sources of gravitational waves ( gws ) in the universe.   stellar tidal disruption events ( tdes ) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the smbh.   about 30 events have been identified by multi - wavelength observations by now, and they will be detected in the thousands in future ground - based or space - based transient surveys.   the study of tdes provides us with a variety of new astrophysical tools and applications, related to fundamental physics or astrophysics. here  , we provide a review of the current status of observations of smbh pairs and binaries, and tdes, and discuss astrophysical implications.
myoglobin single - electron transistors were investigated using nanometer - gap platinum electrodes fabricated by electromigration at cryogenic temperatures.   apomyoglobin ( myoglobin without heme group ) was used as a reference.   the results suggest single electron transport is mediated by resonant tunneling with the electronic and vibrational levels of the heme group in a single protein.   they also represent a proof - of - principle that proteins with redox centers across nanometer - gap electrodes can be utilized to fabricate single - electron transistors.   the protein orientation and conformation may significantly affect the conductance of these devices.   future improvements in device reproducibility and yield will require control of these factors.
the recently released chandra transmission grating catalog and archive, * _ _ tgc__at *, presents a fully dynamic on - line catalog allowing users to browse and categorize chandra gratings observations quickly and easily, generate custom plots of resulting response corrected spectra on - line without the need for special software and to download analysis ready products from multiple observations in one convenient operation. * _ _ tgc__at * has been registered as a vo resource with the nvo providing direct access to the catalogs interface.   the catalog is supported by a back - end designed to automatically fetch newly public data, process, archive and catalog them, at the same time utilizing an advanced queue system integrated into the archive s mysql database allowing large processing projects to take advantage of an unlimited number of cpus across a network for rapid completion.   a unique feature of the catalog is that all of the high level functions used to retrieve inputs from the chandra archive and to generate the final data products are available to the user in an isis written library with detailed documentation. here   we present a structural overview of the systems, design, and accessibility features of the catalog and archive.
the apparent change in the composition of the parent optical objects of radio sources around 1 mjy ( at 1.4 ghz ) is now well established, although there is still some debate about the relative importance of classical radio galaxies and star - forming galaxies at sub - mjy levels ( see e.g. gruppioni et al. 1999,   mnras, 304, 199 ; prandoni et al.   2001b, a&a, 369, 787 ).   it is clear, however, that at @xmath0jy levels star - forming galaxies are dominant ( see fomalont et al. 1997,   apj, 475, l5 ; haarsma et al.   2000, apj, 544, 641 ).   + does this mean that ska will basically tell us more about the history of star formation than about the space density ( and its cosmological evolution ) of active galactic nuclei? + using current best estimates of luminosity functions ( and their evolution ) of various classes of objects, we show that the increasing dominance of star - forming galaxies below 1 mjy is a natural consequence of the different luminosity functions, but that this does not at all mean that star - forming galaxies do necessarily dominate at all sub - mjy flux levels and all redshifts.
we present exact solutions of the ( 0 + 1)-dimensional kinetic equation for a massive gas in the relaxation time approximation. at first, we analyse the case of classical statistics and argue that the traditional second - order hydrodynamics misses the shear - bulk coupling. in the next step,   we include bose - einstein and fermi - dirac statistics in the calculations and show that they are important for description of the effects connected with bulk viscosity.
we present an improved measurement of the rossiter - mclaughlin effect for the exoplanetary system hd  17156, based on radial - velocity data gathered with the subaru 8.2 m telescope throughout the planetary transit of ut  2008  november  7.   the data allow for a precise and independent determination of the projected spin - orbit angle of this system : @xmath0.   this result supersedes the previous claim of @xmath1 by narita et al., which was based on lower - precision data with poor statistics.   thus the stellar spin and planetary orbital axes of the hd  17156 system are likely to be well - aligned, despite the planet s large orbital eccentricity suggesting a history of strong dynamical interactions.
in this paper we report and compare the numerical results for an ocean circulation model obtained by the classical truncated boundary formulation, the free boundary approach and a quasi - uniform grid treatment of the problem.   we apply a shooting method to the truncated boundary formulation and finite difference methods to both the free boundary approach and the quasi - uniform grid treatment. using the shooting method, supplemented by the newton s iterations  , we show that the ocean circulation model can not be considered as a simple test case.   in fact, for this method we are forced to use as initial iterate a value close to the correct missing initial condition in order to be able to get a convergent numerical solution.   the reported numerical results allow us to point out how the finite difference method with a quasi - uniform grid is the less demanding approach and that the free boundary approach provides a more reliable formulation than the classical truncated boundary formulation.   * key words. * nonlinear boundary value problems, infinite intervals, shooting methods, free boundary formulation, quasi - uniform grid, finite difference methods.    * ams subject classifications.   * 65l10, 65l12, 34b40.
the results of @xmath0c nmr spectra and nuclear spin - lattice relaxation rate @xmath1 for the quasi - one - dimensional quarter - filled organic material ( tmttf)@xmath2scn are presented.   a new inhomogeneous line appears below the anion ordering temperature ( @xmath3 ), below which the intensity of the distinct line owing to the inner carbon site from the inversion center is halved.   this indicates that the charge transfer ( disproportionation ) occurs from one inner carbon site to the other inner site exclusively within one unit cell triggered by anion ordering.   the @xmath1 for the charge - donating inner site shows activated temperature dependence below @xmath3, although @xmath1 for the outer carbon decreases much more moderately in lowering temperature as has been discussed in weakly interacting one dimensional conductors.   our observation of the local gap for the spin excitation generated by anion ordering is consistent with the simple model assuming only the electrostatic interaction between the inner carbon sites and ordered anions, which is known to be much closer to the inner sites than to the outer sites.   nevertheless, we reveal that only the electrostatic interaction between the anions and molecules is insufficient to reproduce the observed divergence of the frequency shift and the linewidth of the inhomogeneous line stemming from the charge - accepting inner site at a much lower temperature than @xmath3.
we study homogenization properties of the discrete laplace operator with random conductances on a large domain in @xmath0.   more precisely, we prove almost - sure homogenization of the discrete poisson equation and of the top of the dirichlet spectrum.   we assume that the conductances are stationary, ergodic and nearest - neighbor conductances are positive.   in contrast to earlier results, we do not require uniform ellipticity but certain integrability conditions on the lower and upper tails of the conductances.   we further allow jumps of arbitrary length.    without the long - range connections,   the integrability condition on the lower tail is optimal for spectral homogenization.   it coincides with a necessary condition for the validity of a local central limit theorem for the random walk among random conductances. as an application of spectral homogenization  , we prove a quenched large deviation principle for the normalized and rescaled local times of the random walk in a growing box.    our proofs   are based on a compactness result for the laplacian s dirichlet energy, poincar inequalities, moser iteration and two - scale convergence.           
using high - resolution n - body / sph simulations with @xmath0 particles, we investigate the evolution of stellar and gaseous galactic cores during the hierarchical formation of a spiral galaxy.   we find that the galactic core ( @xmath1 pc ) coevolves with the host galaxy.   the average mass ratio between the baryonic core and the halo is nearly constant, @xmath2 0.04 from @xmath3 to @xmath4.   however, there are several ` rapid - growing phases'during the evolution, in which the rate of mass accretion to the central sub - kpc region is ten times higher ( @xmath5 yr pc@xmath6 ) than the average accretion rate. the rapid growth of the inner core is associated with the major merger events with a time - delay.   we also find that the spin - axis of the gas core frequently changes. as a result,   the angular momentum vector of the central part of the galaxy is independent of the rotation of the outer part.   our results suggest that if a constant fraction of the baryonic mass in the central several 100 pc of a galaxy is converted into a massive black hole, the black hole mass should correlate with the total mass of the galaxies.
following a summary of the basic principles of pulsar timing, we present a review of recent results from timing observations of relativistic binary pulsars. in particular, we summarize the status of timing observations of the much celebrated original binary pulsar psr  b1913 + 16, draw attention to the recent confirmation of strong evidence for geodetic precession in this system, review the recent measurement of multiple post - keplerian binary parameters for psr  b1534 + 12, and describe the parkes multibeam survey, a major survey of the galactic plane which promises to discover new relativistic binary pulsar systems.
the paper deals with a dynamical system analysis of the cosmological evolution of an holographic dark energy ( hde ) model interacting with dark matter ( dm ) which is chosen in the form of dust.   the infrared cut - off of the holographic model is considered as future event horizon or ricci length scale.   +   + the interaction term between dark energy and dark matter is chosen of following three types + i ) proportional to the sum of the energy densities of the two dark components + ii ) proportional to the product of the matter energy densities and + iii ) proportional to dark energy density. +   the dynamical equations are reduced to an autonomous system for the three cases and corresponding phase space is analyzed.   +   + keywords : holographic dark energy, interaction, autonomous system, phase plane.   + pacs numbers : 04.20.-q, 98.80.cq, 95.36.+x
since the discovery of the cuprate high - temperature superconductivity in 1986, a universal phase diagram has been constructed experimentally and numerous theoretical models have been proposed. however, there remains no consensus on the underlying physics thus far.   here, we theoretically investigate the phase diagram of hole - doped cuprates based on an itinerant - localized dual fermion model, with the charge carriers doped on the oxygen sites and localized holes on the copper @xmath0 orbitals.   we analytically demonstrate that the puzzling anomalous normal state or the strange metal could simply stem from a free fermi gas of carriers bathing in copper antiferromagnetic spin fluctuations.   the short - range high - energy spin excitations also act as the ` magnetic glue'of carrier cooper pairs and induce @xmath1-wave superconductivity from the underdoped to overdoped regime, distinctly diffrent from the conventional low - freqency magnetic fluctuation mechanism.   we further sketch out the characteristic dome - shaped critical temperature @xmath2 versus doping level.   the emergence of the pseudogap is ascribed to the localization of partial carriers coupled to the local copper moments or a crossover from the strange metal to a nodal kondo - like insulator.   our work provides a consistent theoretical framework to understand the typical phase diagram of hole - doped cuprates and paves a distinct way to the studies of both non - fermi liquid and unconventional superconductivity in strongly correlated systems.
we critically discuss the concept of `` synchronized flow '' from a historical, empirical, and theoretical perspective.   problems related to the measurement of vehicle data are highlighted, and questionable interpretations are identified.   moreover, we propose a quantitative and consistent theory of the empirical findings based on a phase diagram of congested traffic states, which is universal for all conventional traffic models having the same instability diagram and a fundamental diagram.   new empirical and simulation data supporting this approach are presented as well.   we also give a short overview of the various phenomena observed in panicking pedestrian crowds relevant from the point of evacuation of buildings, ships, and stadia.   some of these can be applied to the optimization of production processes, e.g. the `` slower - is - faster effect ''.   = 1.0 cm
the classical gibbs - donnan equilibrium describes excess osmotic pressure associated with confined colloidal charges embedded in an electrolyte solution. in this work,   we extend this approach to describe the influence of multivalent ion binding on the equilibrium force acting on a charged rod translocating between two compartments, thereby mimicking ionic effects on force balance during _ in vitro _ dna ejection from bacteriophage.   the subtle interplay between gibbs - donnan equilibrium and adsorption equilibrium leads to a non - monotonic variation of the ejection force as multivalent salt concentration is increased, in qualitative agreement with experimental observations.
we explore the link between soft vibrational modes and local relaxation events in polymer glasses during physical aging, active deformation at constant strain rate, and subsequent recovery.   a softness field is constructed out of the superposition of the amplitudes of the lowest energy normal modes, and found to predict up to 70% of the rearrangements.   overlap between softness and rearrangements increases logarithmically during aging and recovery phases as energy barriers rise due to physical aging, while yielding rapidly rejuvenates the overlap to that of a freshly prepared glass. in the strain hardening regime, correlations rise for uniaxial tensile deformation but not for simple shear.   these trends can be explained by considering the differing degrees of localization of the soft modes in the two deformation protocols.
neo s come close to the earth s orbit so that any dust ejected from them, might be seen as a meteor shower.   orbits evolve rapidly, so that a similarity of orbits at one given time is not sufficient to prove a relationship, orbital evolution over a long time interval also has to be similar.   sporadic meteoroids can not be associated with a single parent body, they can only be classified as cometary or asteroidal.   however, by considering one parameter criteria, many sporadics are not classified properly therefore two parameter approach was proposed.
we present three - dimensional solutions of the magnetohydrostatic equations in the co - rotating frame of reference outside a magnetized rigidly rotating cylinder.   we make no symmetry assumption for the magnetic field, but to be able to make analytical progress we neglect outflows and specify a particular form for the current density.   the magnetohydrostatic equations can then be reduced to a single linear partial differential equation for a pseudo - potential @xmath0, from which the magnetic field can be calculated by differentiation.   the equation for @xmath0 can be solved by standard methods.   the solutions can also be used to determine the plasma pressure, density and temperature as functions of all three spatial coordinates. despite the obvious limitations of this approach  , it can for example be used as a simple tool to create three - dimensional models for the closed field line regions of rotating magnetospheres without rotational symmetry.   magnetohydrodynamics ; analytical solutions ; rotating magnetospheres ; three - dimensional equilibria
we study ultrarelativistic encounters of two spinning, equal - mass black holes through simulations in full numerical relativity.   two initial data sequences are studied in detail : one that leads to scattering and one that leads to a grazing collision and merger. in all cases,   the initial black hole spins lie in the orbital plane, a configuration that leads to the so - called _   superkicks_. in astrophysical, quasicircular inspirals, such kicks can be as large as @xmath0 ; here, we find configurations that exceed @xmath1.   we find that the maximum recoil is to a good approximation proportional to the total amount of energy radiated in gravitational waves, but largely _ independent _ of whether a merger occurs or not.   this shows that the mechanism predominantly responsible for the superkick is not related to merger dynamics.   rather, a consistent explanation is that the `` bobbing '' motion of the orbit causes an asymmetric beaming of the radiation produced by the in - plane orbital motion of the binary, and the net asymmetry is balanced by a recoil.   we use our results to formulate some conjectures on the ultimate kick achievable in any black hole encounter.
we have investigated the motion of vortex domain walls passing across non symmetric triangular notches in single permalloy nanowires.   we have measured hysteresis cycles using the focused magneto - optical kerr effect before and beyond the notch, which allowed to probe beyond the notch the occurrence probability of clockwise ( cw ) and counter - clockwise ( ccw ) walls in tail - to - tail ( tt ) and head - to - head ( hh ) configurations.   we present experimental evidence of chirality flipping provided by the vortex  notch interaction. with a low exit angle the probability of chirality flipping increases and   here with the lowest angle of 15@xmath0 the probability of propagation of the energetically favored domain wall configuration ( ccw for tt or cw for hh walls ) is @xmath1.   micromagnetic simulations reveal details of the chirality reversal dynamics.
we present a time - dependent radiative model for the atmosphere of extrasolar planets that takes into account the eccentricity of their orbit.   in addition to the modulation of stellar irradiation by the varying planet - star distance, the pseudo - synchronous rotation of the planets may play a significant role.   we include both of these time - dependent effects when modeling the planetary thermal structure.   we investigate the thermal structure, and spectral characteristics for time - dependent stellar heating for two highly eccentric planets.   finally, we discuss observational aspects for those planets suitable for _ spitzer _ measurements, and investigate the role of the rotation rate.
we report the discovery of pulsations in three mixed - atmosphere, extremely low - mass white dwarf ( elm wd, @xmath0  0.3  @xmath1 ) precursors. following the recent discoveries of pulsations in both elm and pre - elm wds,   we targeted pre - elm wds with mixed h / he atmospheres with high - speed photometry.   we find significant optical variability in all three observed targets with periods in the range 320590  s, consistent in time - scale with theoretical predictions of @xmath2-mode pulsations in mixed - atmosphere @xmath3  0.18  @xmath1  he - core pre - elm wds.   this represents the first empirical evidence that pulsations in pre - elm wds can only occur if a significant amount of he is present in the atmosphere.   future, more extensive, timeseries photometry of the brightest of the three new pulsators offers an excellent opportunity to constrain the thickness of the surface h layer, which regulates the cooling timescales for elm wds.
the very massive star, eta carinae ( @xmath0 car ), is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in c and o, and enriched in he and n. this circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line - of - sight.   the velocity component at @xmath1513  kms@xmath2 exhibits very low ionization with predominantly neutral species of iron - peak elements.   our statistical equilibrium / photoionization modeling indicates that the low temperature ( t = 760 k ) and high density ( n@xmath3@xmath410@xmath5 @xmath6 ) of the @xmath1513  kms@xmath2component is conducive to molecule formation including those with the elements c and o. examination of echelle spectra obtained with the space telescope imaging spectrograph ( stis ) aboard the _ hubble space telescope ( hst ) _ confirms the model s predictions.   the molecules, h@xmath7, ch, and most likely oh, have been identified in the @xmath1513 kms@xmath2 absorption spectrum.   this paper presents the analysis of the _ hst_/stis spectra with the deduced column densities for ch, oh and c i, and upper limit for co. it is quite extraordinary to see molecular species in a cool environment at such a high velocity.   the sharp molecular and ionic absorptions in this extensively cno- processed material offers us a unique environment for studying the chemistry, dust formation processes, and nucleosynthesis in the ejected layers of a highly evolved massive star.
we have identified spectral features in the late - time x - ray afterglow of the unusually long, slow - decaying grb130925a  using _ nustar _, _ swift_-xrt, and _ chandra_. a spectral component in addition to an absorbed power - law is required at @xmath0 significance, and its spectral shape varies between two observation epochs at @xmath1 and @xmath2 seconds after the burst.   several models can fit this additional component, each with very different physical implications. a broad,   resolved gaussian absorption feature of several kev width improves the fit, but it is poorly constrained in the second epoch. an additive black body or second power - law component provide better fits.   both are challenging to interpret : the blackbody radius is near the scale of a compact remnant ( @xmath3 cm ), while the second powerlaw component requires an unobserved high - energy cutoff in order to be consistent with the non - detection by _ fermi_-lat.
we propose a self - consistant approach to the treatment of nuclear matter as a crystal of solitons in the wigner - seitz approximation.   specifically, we use a bloch - like boundary condition on the quarks at the edge of a spherical cell which allows the dispersion relation for a given radius to be calculated self - consistently along with the meson fields ; in previous work some ansatz for the dispersion relation has always been an input.   results in all models are very sensitive to the form of the dispersion relation, so our approach represents a significant advance.   we apply the method to both the friedberg lee model and the chiral quark - meson model of birse and banerjee. only the latter shows short range repulsion ;   in the former the transition to a quark plasma occurs at unrealistically low densities.
this contribution briefly reviews the reverberation mapping technique which leads to determination of black hole masses.   i focus on the emerging relation between the broad - line region size and the active galactic nucleus ( agn ) luminosity, and on an overview of recent results of reverberation mapping studies which are starting to cover the full agn luminosity range.   preliminary results and time lag determination from a reverberation mapping program of high - luminosity quasars are also presented.
abundance observations indicate the presence of rapid - neutron capture ( i.e., _   r_-process ) elements in old galactic halo and globular cluster stars.   these observations demonstrate that the earliest generations of stars in the galaxy, responsible for neutron - capture synthesis and the progenitors of the halo stars, were rapidly evolving.   abundance comparisons among several halo stars show that the heaviest neutron - capture elements ( including ba and heavier ) are consistent with a scaled solar system _   r_-process abundance distribution, while the lighter such elements do not conform to the solar pattern.   these comparisons suggest two _ r_-process sites or at least two different sets of astrophysical conditions. the large star - to - star scatter observed in the neutron - capture / iron ratios at low metallicities  which disappears with increasing   suggests an early, chemically unmixed and inhomogeneous galaxy.   the stellar abundances indicate a change from the _   r_-process to the slow neutron capture ( i.e., s- ) process at higher metallicities in the galaxy.   the detection of thorium in halo and globular cluster stars offers a promising, independent age - dating technique that can put lower limits on the age of the galaxy.
we analyze, through resonant photoluminescence, the spin dynamics of an individual magnetic atom ( mn ) coupled to a hole in a semiconductor quantum dot.   the hybrid mn - hole spin and the positively charged exciton in a cdte / znte quantum dot forms an ensemble of @xmath0 systems which can be addressed optically.   auto - correlation of the resonant photoluminescence and resonant optical pumping experiments are used to study the spin relaxation channels in this multilevel spin system.   we identified for the hybrid mn - hole spin an efficient relaxation channel driven by the interplay of the mn - hole exchange interaction and the coupling to acoustic phonons.   we also show that the optical @xmath0 systems are connected through inefficient spin - flips than can be enhanced under weak transverse magnetic field.   the dynamics of the resonant photoluminescence in a p - doped magnetic quantum dot is well described by a complete rate equation model.   our results suggest that long lived hybrid mn - hole spin could be obtained in quantum dot systems with large heavy - hole / light - hole splitting.
the detailed observations of the diffuse ionized gas through the emission lines h@xmath0, , and  in the perseus arm of our galaxy by the wisconsin h@xmath0 mapper ( wham)survey challenge photoionization models. they have to explain the observed rise in the line ratios /h@xmath0 and /h@xmath0.   the models described here consider for the first time the detailed observational geometry toward the perseus arm.   the models address the vertical variation of the line ratios up to height of 2 kpc above the midplane.   the rising trends of the line ratios are matched.   the increase in the line ratios is reflected in a rise of the temperature of the gas layer.   this is due to the progressive hardening of the radiation going through the gas.   however an extra heating above photoionization is needed to explain the absolute values.   two different extra heating rates are investigated which are proportional to @xmath1 and @xmath2.   the models show that a combination of both are best to explain the data, where the extra heating independent of density is dominant for z @xmath3 0.8 kpc.
cls is an evolution code recently developed to produce stellar models meeting the specific requirements of studies in asteroseismology.   it offers the users a lot of choices in the input physics they want in their models and its versatility allows them to tailor the code to their needs and implement easily new features.   we describe the features implemented in the current version of the code and the techniques used to solve the equations of stellar structure and evolution.   a brief account is given of the use of the program and of a solar calibration realized with it.
a two - dimensional ( 2d ) shock - rest - frame model for particle simulations is developed.   then full kinetic dynamics of a perpendicular collisionless shock is examined by means of a 2d full particle simulation.   we found that in the 2d simulation there are fewer nonthermal electrons due to surfing acceleration which was seen in the previous 1d simulations of a high mach number perpendicular shock in a low - beta and weakly magnetized plasma.   this is because the particle motion along the ambient magnetic field disturbs the formation of coherent electrostatic solitary structures which is necessary for electron surfing acceleration.
we present a comparative study of two computer simulation methods to obtain static and dynamic properties of dilute polymer solutions.   the first approach is a recently established hybrid algorithm based upon dissipative coupling between molecular dynamics and lattice boltzmann ( lb ), while the second is standard brownian dynamics ( bd ) with fluctuating hydrodynamic interactions.   applying these methods to the same physical system ( a single polymer chain in a good solvent in thermal equilibrium ) allows us to draw a detailed and quantitative comparison in terms of both accuracy and efficiency.   it is found that the static conformations of the lb model are distorted when the box length @xmath0 is too small compared to the chain size.   furthermore, some dynamic properties of the lb model are subject to an @xmath1 finite size effect, while the bd model directly reproduces the asymptotic @xmath2 behavior. apart from these finite size effects  , it is also found that in order to obtain the correct dynamic properties for the lb simulations, it is crucial to properly thermalize all the kinetic modes. only in this case  , the results are in excellent agreement with each other, as expected.   moreover, brownian dynamics is found to be much more efficient than lattice boltzmann as long as the degree of polymerization is not excessively large.
models which accelerate the expansion of the universe through the addition of a function of the ricci scalar @xmath0 leave a characteristic signature in the large - scale structure of the universe at the compton wavelength scale of the extra scalar degree of freedom.   we search for such a signature in current cosmological data sets : the wmap cosmic microwave background ( cmb ) power spectrum, snls supernovae distance measures, the sdss luminous red galaxy power spectrum, and galaxy - cmb angular correlations.   due to theoretical uncertainties in the nonlinear evolution of @xmath0 models, the galaxy power spectrum conservatively yields only weak constraints on the models despite the strong predicted signature in the linear matter power spectrum. currently the tightest constraints involve the modification to the integrated sachs - wolfe effect from growth of gravitational potentials during the acceleration epoch.   this effect is manifest for large compton wavelengths in enhanced low multipole power in the cmb and anti - correlation between the cmb and tracers of the potential.   they place a bound on the compton wavelength of the field be less than of order the hubble scale.
the experimental time scale dependence of thermodynamic relations in out - of - equilibrium systems with aging phenomena is investigated theoretically by using only aging properties of the two - time correlation functions and the generalized fluctuation - dissipation theorem ( fdt ).   we show that there are two experimental time regimes characterized by different thermal properties. in the first regime where the waiting time is much longer than the measurement time,   the principle of minimum work holds even though a system is out of equilibrium. in the second regime where both the measurement time and the waiting time are long, the thermal properties are completely different from properties in equilibrium. for the single - correlation - scale systems such as   @xmath0-spin spherical spin - glasses, contrary to a fundamental assumption of thermodynamics, the work done in an infinitely slow operation depends on the path of change of the external field even when the waiting time is infinite. on the other hand, for the multi - correlation - scale systems such as sherrington - kirkpatrick model,   the work done in an infinitely slow operation is independent of the path.   our results imply that in order to describe thermodynamic properties of systems with aging it is essential to consider the experimental time scales and history of a system as a state variable is necessary.   # 1@xmath1#1
the experimental binding energies of single - particle and single - hole neutron states belonging to neutron shells that extend from n = 126 to 184 and 82 to 126 respectively, have been reproduced by solving the schrdinger equation with a potential that has two components : the generalized woods - saxon ( gws ) potential and the spin - orbit ( so ) coupling term.   the gws potential contains the traditional ws potential plus a term ( su ) whose intensity reaches a maximum in the nuclear surface.   our results indicate the existence of a explicit relationship between the strength of the su potential and the orbital angular momentum quantum number @xmath0 of the state. this dependence has been used to make reasonable predictions for the excitation energy centroids of states located inside and outside the neutron shells investigated.   comparisons are made with results reported in previous investigations.
the definition of preferences assigned to individuals is a concept that concerns many disciplines, from economics, with the search of an acceptable outcome for an ensemble of individuals, to decision making an analysis of vote systems.   we are concerned in the phenomena of good selection and economic fairness. in arrow   s theorem this situation is expressed as the impossibility of aggregate preferences among individuals falling down into some unfairness state.   this situation was also analyzed in a previous model in a network of individuals with a random allocation @xcite.   both analysis are based on static preferences.    in a real society   the individuals are confronted to information exchange which can modify the way that they think.   also, the preference formation of each individual is influenced by this exchange.   this consideration reveals why the actual theory is not able to make an accurate analysis of the influence of the individual, or cluster of individuals, in the fairness state.   the aim of this investigation is to consider the coupling of two systems, one for the formation of preferences and a second where an allocation of goods is done in an evolutionary environment.
a description of mesoscopic fluctuations of the pairing gap in finite - sized quantum systems based on periodic orbit theory is presented.   the size of the fluctuations are found to depend on quite general properties.   we distinguish between systems where corresponding classical motion is regular or chaotic, and describe in detail fluctuations of the bcs gap as a function of the size of the system.   the theory is applied to different mesoscopic systems : atomic nuclei, metallic grains, and ultracold fermionic gases.   we also present a detailed description of pairing gap variation with particle number for nuclei based on a deformed cavity potential.
we study the swimming of non - relativistic deformable bodies in ( empty ) static curved spaces.   we focus on the case where the ambient geometry allows for rigid body motions. in this case   the swimming equations turn out to be geometric. for a small swimmer,   the swimming distance in one stroke is determined by the riemann curvature times certain moments of the swimmer.
we use atmospheric neutrino data and minos data to constrain the mavan ( mass varying neutrinos ) mechanism.   the mavan model was largely studied in cosmology scenarios and comes from the coupling of the neutrinos with a neutral scalar depending on the local matter density. for atmospheric neutrinos  , this new interaction affects the neutrino propagation inside the earth, and as consequence, induces modifications in their oscillation pattern. to perform such test for a non - standard oscillation mechanism with a non - diagonal neutrino coupling in the mass basis  , we analyze the angular distribution of atmospheric neutrino events as seen by the super - kamiokande experiment for the events in the sub - gev and multi - gev range and muon neutrinos ( anti - neutrinos ) in minos experiment. from the combined analysis of these two sets of data   we obtain the best fit for @xmath0  ev@xmath1, @xmath2 and mavan parameter @xmath3 with modest improvement, @xmath4, over the standard oscillation scenario.   the combination of minos data and super - kamiokande data prefers small values of mavan parameter @xmath5 at 90% c. l..
we show that the maximal number of singular moves required to pass between any two regularly homotopic planar or spherical curves with at most @xmath0 crossings, grows quadratically with respect to @xmath0.   furthermore, this can be done with all curves along the way having at most @xmath1 crossings.    lemma proposition corollary definition remark example
one of the fundamental and yet untested predictions of inflationary models is the generation of a very weak cosmic background of gravitational radiation.   we investigate the sensitivity required for a space - based gravitational wave laser interferometer with peak sensitivity at @xmath0 hz to observe such signal as a function of the model parameters and compare it with indirect limits that can be set with data from present and future cosmic microwave background missions.   we concentrate on signals predicted by slow - roll single field inflationary models and instrumental configurations such as those proposed for the lisa follow - on mission : big bang observer.
the fully symmetric gaussian tripartite entangled pure states will not exhibit two - mode einstein podolsky - rosen ( epr)-steering. this means that any two participants can not share quantum secrets using the security of one - sided device independent quantum key distribution ( 1sdi - qkd ) without involving the third.   they are restricted at most to standard quantum key distribution ( s - qkd ), which is less secure. here   we demonstrate an asymmetric tripartite system that can exhibit bipartite epr - steering, so that two of the participants can use 1sdi - qkd without involving the other.   this is possible because the promiscuity relations of continuous - variable tripartite entanglement are different from those of discrete - variable systems.   we analyse these properties for two different systems, showing that the asymmetric system exhibits practical properties not found in the symmetric one.
neutrinoless double beta decay is a process that violates lepton number conservation.   it is predicted to occur in extensions of the standard model of particle physics.   this letter reports the results from phase  i of the germanium detector array ( gerda ) experiment at the gran sasso laboratory ( italy ) searching for neutrinoless double beta decay of the isotope @xmath0ge.   data considered in the present analysis have been collected between november 2011 and may 2013 with a total exposure of 21.6  kg@xmath1yr.   a blind analysis is performed.   the background index is about @xmath2  cts/(kev@xmath1kg@xmath1yr )  after pulse shape discrimination.   no signal is observed and a lower limit is derived for the half - life of neutrinoless double beta decay of @xmath0ge, @xmath3@xmath4  yr ( 90  % c.l. ). the combination with the results from the previous experiments with @xmath0ge  yields @xmath3@xmath5  yr ( 90  % c.l. ).
though widely observed to be emanating from a variety of astrophysical sources, the underlying physical mechanism behind the formation of galactic and extragalactic outflows is still enshrouded in a veil of mystery. in addition, it has not been possible to calculate accurately the amount of matter expelled in these events. in this article   we present a _ non - self - similar analytical model _, which, for the first time, we believe is able to explain the outflow formation phenomenon as well as compute the mass outflow rate by simultaneously solving the equations governing the exact transonic accretion and outflow. our model predicts the dependence of this rate on various flow parameters as well as the _ exact _ location from where the outflows are launched.
a method to calculate the bound states of three - atoms without resorting to an explicit partial wave decomposition is presented.   the differential form of the faddeev equations in the total angular momentum representation is used for this purpose.   the method utilizes cartesian coordinates combined with the tensor - trick preconditioning for large linear systems and arnoldi s algorithm for eigenanalysis. as an example, we consider the he@xmath0 system in which the interatomic force has a very strong repulsive core that makes the three - body calculations with standard methods tedious and cumbersome requiring the inclusion of a large number of partial waves.   the results obtained compare favorably with other results in the field.   +   + pacs numbers : 21.45.+v, 36.90.+f,02.70.jn
it has recently been discovered that for certain rates of mode - exchange collisions analytic solutions can be found for a hamiltonian describing the two - mode bose - einstein condensate.   we proceed to study the behaviour of the system using perturbation theory if the coupling constants only approximately match these parameter constraints.   we find that the model is robust to such perturbations.   we study the effects of degeneracy on the perturbations and find that the induced changes differ greatly from the non - degenerate case.   we also model inelastic collisions that result in particle loss or condensate decay as external perturbations and use this formalism to examine the effects of three - body recombination and background collisions.    * a perturbative approach to inelastic collisions in a bose - einstein condensate * + r.b.   mann@xmath0, m. b. young@xmath1, i. fuentes - schuller@xmath2    _ @xmath3 department of physics & astronomy, university of waterloo, + waterloo, ontario, n2l 3g1, canada _    _ @xmath4 perimeter institute for theoretical physics, +  waterloo, ontario, n2l 2y5, canada _   _ @xmath5 department of mathematics, state university of new york at stony brook, + stony brook, new york, 11794 - 3651, u.s.a. _    _ @xmath6 institute for theoretical physics, technical university of berlin, + hardenbergstr.   36, d-10623, berlin, germany _   _ @xmath7 institute of physics, university of potsdam, + am neuen   palais
the influence of hydrodynamic interactions on lane formation of oppositely charged driven colloidal suspensions is investigated using brownian dynamics computer simulations performed on the rotne - prager level of the mobility tensor.   two cases are considered, namely sedimentation and electrophoresis. in the latter case the oseen contribution to the mobility tensor is screened due to the opposite motion of counterions.   the simulation results are compared to that resulting from simple brownian dynamics where hydrodynamic interactions are neglected. for sedimentation, we find that hydrodynamic interactions strongly disfavor laning. in the steady - state of lanes, a macroscopic phase separation of lanes   is observed.   this is in marked contrast to the simple brownian case where a finite size of lanes was obtained in the steady - state. for strong coulomb interactions between the colloidal particles a lateral square lattice of oppositely driven lanes is stable similar to the simple brownian dynamics. in an electric field, on the other hand  , the behavior is found in qualitative and quantitative accordance with the case of neglected hydrodynamics.
a next - to - leading order analysis of inelastic electroproduction of charm is performed using an interpolating scheme which maps smoothly onto massless qcd evolution at large @xmath0 and photon  gluon fusion at small @xmath0.   in contrast with earlier analyses, this scheme allows the inclusion of quark and target mass effects and heavy quark thresholds, as well as possible non - perturbative, or intrinsic, charm contributions.   we find no conclusive evidence in favor of an intrinsic charm component in the nucleon, although several data points which disagree with perturbative qcd expectations will need to be checked by future experiments.
the symbolic manipulation program form is specialized to handle very large algebraic expressions  . some specific features of its internal structure make form very well suited for parallelization.   after an introduction to the sequential version of form and the mechanisms behind, we report on the status of our project of parallelization.   we have now a parallel version of form running on cluster- and smp - architectures.   this version can be used to run arbitrary form programs in parallel.
the application of multi - wavelength selection techniques is crucial for discovering a complete and unbiased set of active galactic nuclei ( agns ). here  , we select a sample of 72 agn candidates in the extended groth strip ( egs ) using deep radio and mid - infrared data from the very large array ( vla ) and the _ spitzer space telescope _, and analyze their properties across other wavelengths.   only 30% of these sources are detected in deep 200 ks _ chandra x - ray observatory _ pointings.   the x - ray detected sources demonstrate moderate obscuration with column densities of @xmath0 2. a stacked image of sources undetected by _   chandra _ shows low levels of x - ray activity, suggesting they may be faint or obscured agns.   less than 40% of our sample are selected as agns with optical broad lines, mid - infrared power laws, or x - ray detections.   thus, if our candidates are indeed agns, the radio / mid - infrared selection criteria we use provide a powerful tool for identifying sources missed by other surveys.
we present an algorithm capable of identifying a wide variety of human - induced change on the surface of the planet by analyzing matches between local features in time - sequenced remote sensing imagery.   we evaluate feature sets, match protocols, and the statistical modeling of feature matches. with application of kaze features, k - nearest - neighbor descriptor matching, and geometric proximity and bi - directional match consistency checks, average match rates increase more than two - fold over the previous standard. in testing our platform, we developed a small, labeled benchmark dataset expressing large - scale residential, industrial, and civic construction, along with null instances, in california between the years 2010 and 2012.   on the benchmark set, our algorithm makes precise, accurate change proposals on two - thirds of scenes.   further, the detection threshold can be tuned so that all or almost all proposed detections are true positives.
the largest stellar halos in the universe are found in massive galaxy clusters, where interactions and mergers of galaxies, along with the cluster tidal field, all act to strip stars from their host galaxies and feed the diffuse intracluster light ( icl ) and extended halos of brightest cluster galaxies ( bcgs ).   studies of the nearby virgo cluster reveal a variety of accretion signatures imprinted in the morphology and stellar populations of its icl.   while simulations suggest the icl should grow with time, attempts to track this evolution across clusters spanning a range of mass and redshift have proved difficult due to a variety of observational and definitional issues.   meanwhile, studies of nearby galaxy groups reveal the earliest stages of icl formation : the extremely diffuse tidal streams formed during interactions in the group environment.
gravitational lensing is now widely and successfully used to study a range of astronomical phenomena, from individual objects, like galaxies and clusters, to the mass distribution on various scales, to the overall geometry of the universe. here   we describe and assess the use of gravitational lensing as `` gold standards '' in addressing one of the fundamental problems in astronomy, the determination of the absolute distance scale to extragalactic objects.   this is commonly parameterized by the hubble constant, @xmath0, the current expansion rate of the universe.   the elegance of the underlying geometrical principle of the gravitational lensing method combined with the recent advances in observations and modelling makes it a very promising technique for measuring @xmath0.
we study the dynamics of the entanglement structure of a multipartite system experiencing a dissipative evolution.   we characterize the processes leading to a particular form of output system entanglement and provide a recipe for their identification via concatenations of particular linear maps with entanglement - breaking operations.   we illustrate the applicability of our approach by considering local and global depolarizing noises acting on general multiqubit states.   a difference in the typical entanglement behavior of systems subjected to these noises is observed : the originally genuine entanglement dissociates by splitting off particles one by one in the case of local noise, whereas intermediate stages of entanglement clustering are present in the case of global noise.   we also analyze the definitive phase of evolution when the annihilation of the entanglement compound finally takes place.
the minimum current corona ( mcc ) model provides a way to estimate stored coronal energy using the number of field lines connecting regions of positive and negative photospheric flux.   this information is quantified by the net flux connecting pairs of opposing regions in a connectivity matrix.   changes in the coronal magnetic field, due to processes such as magnetic reconnection, manifest themselves as changes in the connectivity matrix.   however, the connectivity matrix will also change when flux sources emerge or submerge through the photosphere, as often happens in active regions.   we have developed an algorithm to estimate the changes in flux due to emergence and submergence of magnetic flux sources.   these estimated changes must be accounted for in order to quantify storage and release of magnetic energy in the corona. to perform this calculation over extended periods of time  , we must additionally have a consistently labeled connectivity matrix over the entire observational time span.   we have therefore developed an automated tracking algorithm to generate a consistent connectivity matrix as the photospheric source regions evolve over time.   we have applied this method to noaa active region 11112, which underwent a goes m2.9 class flare around 19:00 on oct.@xmath0, 2010, and calculated a lower bound on the free magnetic energy buildup of @xmath1ergs over 3 days.
we are developing a 3d radiation hydrodynamics code to simulate the interaction of convection and pulsation in classical variable stars.   one key goal is the ability to carry these simulations to full amplitude in order to compare them with observed light and velocity curves.   previous 2d calculations were prevented from doing this because of drift in the radial coordinate system, due to the algorithm defining radial movement of the coordinate system during the pulsation cycle.   we remove this difficulty by defining our coordinate system flow algorithm to require that the mass in a spherical shell remain constant throughout the pulsation cycle.   we perform adiabatic test calculations to show that large amplitude solutions repeat over more than 150 pulsation periods.   we also verify that the computational method conserves the peak kinetic energy per period, as must be true for adiabatic pulsation models.
we report on results of an observation with the rossi x - ray timing explorer ( rxte ) of psr b1706 - 44 with a live time of 132 ks, to search for pulsed x - ray emission.   psr b1706 - 44 is a radio and high - energy gamma - ray pulsar ( detected by egret ), but no pulsed emission has been detected in the x - ray band. since most of the other known gamma - ray pulsars emit pulsed x - rays, it is expected that psr b1706 - 44 would also be an x - ray pulsar. however, while the rosat pspc detected a source at the pulsar position, it did not detect pulsations, giving a pulsed fraction upper limit of 18%.   the rxte observations to search for modulation at the pulsar period were carried out in november 1996 and may 1997 during the low states of the nearby x - ray binary 4u1705 - 44.   no significant modulation was detected at the pulsar period, giving an upper limit of @xmath0 in the interval 9 kev @xmath1 kev.   the implications of this upper limit of the pulsed flux from the rxte observation, taken together with multiband observations of this pulsar are examined in the context of theoretical models of pulsar particle acceleration zones and associated high energy electromagnetic emission.
information hierarchies are organizational structures that often used to organize and present large and complex information as well as provide a mechanism for effective human navigation.   fortunately, many statistical and computational models exist that automatically generate hierarchies ; however, the existing approaches do not consider linkages in information _ networks _ that are increasingly common in real - world scenarios.   current approaches also tend to present topics as an abstract probably distribution over words, etc rather than as tangible nodes from the original network.   furthermore, the statistical techniques present in many previous works are not yet capable of processing data at web - scale. in this paper we present the hierarchical document topic model ( hdtm ), which uses a distributed vertex - programming process to calculate a nonparametric bayesian generative model. experiments on three medium size data sets and the entire wikipedia dataset show that hdtm can infer accurate hierarchies even over large information networks.   
we examine the motion of a photon in the gravitational field of a binary system.   the equations of motion are geodesic equations in a schwarzchild background with a tidal force.   we specialize the equations to that of an edge - on binary and use the method of osculating elements to integrate them.   this work helps to identify a binary system through the gravitational light deflection of one member in the gravitational field of the other member.   it is found that the effects of the companion body on a photon passing the edge of the star can be potentially detected by astrometric satellites with @xmath0as precision, if the ratio of the schwarzchid radius to the star radius, @xmath1.   two different cumulative effects on the photon path are identified.   = 1
we develop a generalized covering space theory for a class of uniform spaces called coverable spaces.   coverable spaces include all geodesic metric spaces, connected and locally pathwise connected compact topological spaces, in particular peano continua, as well as more pathological spaces like the topologist s sine curve.   each coverable space has a generalized universal cover with universal and lifting properties. associated with this generalized universal cover is a functorial uniform space invariant called the _ deck group _, which is related to the classical fundamental group by a natural homomorphism.   we obtain some specific results for one - dimensional spaces.   keywords : universal cover, uniform space, geodesic space, fundamental group    msc : 55q52 ; 54e15,55m10
we study social cost losses in facility location games, where @xmath0 selfish agents install facilities over a network and connect to them, so as to forward their local demand ( expressed by a non - negative weight per agent ).   agents using the same facility share fairly its installation cost, but every agent pays individually a ( weighted ) connection cost to the chosen location.   we study the price of stability ( pos ) of _ pure _ nash equilibria and the price of anarchy of _ strong _ equilibria ( spoa ), that generalize pure equilibria by being resilient to coalitional deviations. a special case of recently studied network design games, facility location merits separate study as a classic model with numerous applications and individual characteristics : our analysis for unweighted agents on metric networks reveals constant upper and lower bounds for the pos, while an @xmath1 upper bound implied by previous work is tight for non - metric networks.   strong equilibria do not always exist, even for the unweighted metric case.   we show that @xmath2-approximate strong equilibria exist ( @xmath3 ).   the spoa is generally upper bounded by @xmath4 ( @xmath5 is the sum of agents weights ), which becomes tight @xmath6 for unweighted agents. for the unweighted metric case we prove a constant upper bound.   we point out several challenging open questions that arise.
the creation of collective many - body quantum states from a two - dimensional lattice gas of atoms is studied.   our approach relies on the van - der - waals interaction that is present between alkali metal atoms when laser excited to high - lying rydberg s - states.   we focus on a regime in which the laser driving is strong compared to the interaction between rydberg atoms. here   energetically low - lying many - particle states can be calculated approximately from a quadratic hamiltonian.   the potential usefulness of these states as a resource for the creation of deterministic single - photon sources is illustrated.   the properties of these photon states are determined from the interplay between the particular geometry of the lattice and the interatomic spacing.
many fundamental questions concerning the emergence and subsequent evolution of eukaryotic exon - intron organization are still unsettled.   genome - scale comparative studies, which can shed light on crucial aspects of eukaryotic evolution, require adequate computational tools.   we describe novel computational methods for studying spliceosomal intron evolution.   our goal is to give a reliable characterization of the dynamics of intron evolution.   our algorithmic innovations address the identification of orthologous introns, and the likelihood - based analysis of intron data.   we discuss a compression method for the evaluation of the likelihood function, which is noteworthy for phylogenetic likelihood problems in general.   we prove that after @xmath0 preprocessing time, subsequent evaluations take @xmath1 time almost surely in the yule - harding random model of @xmath2-taxon phylogenies, where @xmath3 is the input sequence length.   we illustrate the practicality of our methods by compiling and analyzing a data set involving 18 eukaryotes, more than in any other study to date.   the study yields the surprising result that ancestral eukaryotes were fairly intron - rich.   for example, the bilaterian ancestor is estimated to have had more than 90% as many introns as vertebrates do now.    [    ] contact : + + + + + + + +    csuros at iro.umontreal.ca
vortices have been postulated at a range of size scales in the universe including at the stellar size - scale. whilst hydrodynamically simulating the wind from an asymptotic giant branch ( agb ) star moving through and sweeping up its surrounding interstellar medium ( ism )  , we have found vortices on the size scale of @xmath0 pc to @xmath1 pc in the wake of the star.   these vortices appear to be the result of instabilities at the head of the bow shock formed upstream of the agb star.   the instabilities peel off downstream and form vortices in the tail of agb material behind the bow shock, mixing with the surrounding ism.   we suggest such structures are visible in the planetary nebula sh 2 - 188.
in this paper, we have formulated the new exact model of quintessence anisotropic star in @xmath0 theory of gravity.   the dynamical equations in @xmath0 theory with the anisotropic fluid and quintessence field have been solved by using krori - barua solution. in this case, we have used the starobinsky model of @xmath0 gravity. we have determined that all the obtained solutions are free from central singularity and potentially stable.   the observed values of mass and radius of the different strange stars psr j 1614 - 2230, saxj1808.4 - 3658(ss1 ), 4u1820- 30, psr j 1614 - 2230 have been used to calculate the values of unknown constants in krori and barua metric.   the physical parameters like anisotropy, stability and redshift of the stars have been investigated in detail.    * keywords * : @xmath0 theory of gravity ; quintessence field, krori - barua metric.    *   pacs numbers * : 97.60.jd ; 12.60.-i ; 04.50.kd
in recent years ontologies enjoyed a growing popularity outside specialized ai communities.   system engineering is no exception to this trend, with ontologies being proposed as a basis for several tasks in complex industrial implements, including system design, monitoring and diagnosis. in this paper, we consider four different contributions to system engineering wherein ontologies are instrumental to provide enhancements over traditional ad - hoc techniques. for each application  , we briefly report the methodologies, the tools and the results obtained with the goal to provide an assessment of merits and limits of ontologies in such domains.
we compute multi - instanton amplitudes in the sine - gordon quantum mechanics ( periodic cosine potential ) by integrating out quasi - moduli parameters corresponding to separations of instantons and anti - instantons.   we propose an extension of bogomolnyi  zinn - justin prescription for multi - instanton configurations and an appropriate subtraction scheme.   we obtain the multi - instanton contributions to the energy eigenvalue of the lowest band at the zeroth order of the coupling constant. for the configurations with only instantons ( anti - instantons ), we obtain unambiguous results. for those with both instantons and anti - instantons  , we obtain results with imaginary parts, which depend on the path of analytic continuation.   we show that the imaginary parts of the multi - instanton amplitudes precisely cancel the imaginary parts of the borel resummation of the perturbation series, and verify that our results completely agree with those based on the uniform - wkb calculations, thus confirming the resurgence : divergent perturbation series combined with the nonperturbative multi - instanton contributions conspire to give unambiguous results.   we also study the neutral bion contributions in the @xmath0 model on @xmath1 with a small circumference, taking account of the relative phase moduli between the fractional instanton and anti - instanton.   we find that the sign of the interaction potential depends on the relative phase moduli, and that both the real and imaginary parts resulting from quasi - moduli integral of the neutral bion get quantitative corrections compared to the sine - gordon quantum mechanics.
nonlinear optical generation from a crystalline material can reveal the symmetries of both its lattice structure and underlying ordered electronic phases and can therefore be exploited as a complementary technique to diffraction based scattering probes.   although this technique has been successfully used to study the lattice and magnetic structures of systems such as semiconductor surfaces, multiferroic crystals, magnetic thin films and multilayers, challenging technical requirements have prevented its application to the plethora of complex electronic phases found in strongly correlated electron systems.   these requirements include an ability to probe small bulk single crystals at the micron length scale, a need for sensitivity to the entire nonlinear optical susceptibility tensor, oblique light incidence reflection geometry and incident light frequency tunability among others.   these measurements are further complicated by the need for extreme sample environments such as ultra low temperatures, high magnetic fields or high pressures. in this review   we present a novel experimental construction using a rotating light scattering plane that meets all the aforementioned requirements.   we demonstrate the efficacy of our scheme by making symmetry measurements on a micron scale facet of a small bulk single crystal of sr@xmath0iro@xmath1 using optical second and third harmonic generation.
h.e.s.s is an array of atmospheric cherenkov telescopes dedicated to gev - tev @xmath0-ray astronomy.   the original array has been in operation since the beginning of 2004.   it is composed of four 12-meter diameter telescopes.   the installation of a fifth 28-meter diameter telescope is being completed.   this telescope will operate both in stereoscopic mode and in monoscopic mode _   i.e. _ without a coincident detection on the smaller telescopes.   a second - level trigger system is needed to supress spurious triggers of the 28-meter telescope when operated in monoscopic mode.   this paper gives the motivation and principle of the second - level trigger.   the principle of operation is illustrated by an example algorithm.   the hardware implementation of the second level trigger system of h.e.s.s.   phase 2 is described and its expected performances are then evaluated.
we consider a large number of text data sets. these are cooking recipes. term distribution and other distributional properties of the data   are investigated.   our aim is to look at various analytical approaches which allow for mining of information on both high and low detail scales.   metric space embedding is fundamental to our interest in the semantic properties of this data.   we consider the projection of all data into analyses of aggregated versions of the data.   we contrast that with projection of aggregated versions of the data into analyses of all the data.   analogously for the term set, we look at analysis of selected terms.   we also look at inherent term associations such as between singular and plural.   in addition to our use of correspondence analysis in r, for latent semantic space mapping, we also use apache solr. setting up the solr server and carrying out querying   is described.   a further novelty is that querying is supported in solr based on the principal factor plane mapping of all the data.   this uses a bounding box query, based on factor projections.
we use images of high spatial and temporal resolution, obtained with the rapid oscillations in the solar atmosphere instrument at the dunn solar telescope, to reveal how the generation of transverse waves in type   spicules is a direct result of longitudinal oscillations occurring in the photosphere. here   we show how pressure oscillations, with periodicities in the range 130  440  s, manifest in small - scale photospheric magnetic bright points, and generate kink waves in the sun s outer atmosphere with transverse velocities approaching the local sound speed. through comparison of our observations with advanced two - dimensional magneto - hydrodynamic simulations  , we provide evidence for how magneto - acoustic oscillations, generated at the solar surface, funnel upwards along type   spicule structures, before undergoing longitudinal - to - transverse mode conversion into waves at twice the initial driving frequency.   the resulting kink modes are visible in chromospheric plasma, with periodicities of 65  220  s, and amplitudes often exceeding 400  km.   a sausage mode oscillation also arises as a consequence of the photospheric driver, which is visible in both simulated and observational time series.   we conclude that the mode conversion and period modification is a direct consequence of the 90 degree phase shift encompassing opposite sides of the photospheric driver.   the chromospheric energy flux of these waves are estimated to be @xmath03@xmath1  wm@xmath2, which indicates that they are sufficiently energetic to accelerate the solar wind and heat the localized corona to its multi - million degree temperatures.
we study the effect of electron - electron interactions in the electronic properties of a biased graphene bilayer.   this system is a semiconductor with conduction and valence bands characterized by an unusual `` mexican - hat '' dispersion.   we focus on the metallic regime where the chemical potential lies in the `` mexican - hat '' in the conduction band, leading to a topologically non - trivial fermi surface in the shape of a ring.   we show that due to the unusual topology of the fermi surface electron - electron interactions are greatly enhanced.   we show that the ferromagnetic instability can occur provided a low density of carriers.   we compute the electronic polarization function in the random phase approximation and show that, while at low energies the system behaves as a fermi liquid ( albeit with peculiar friedel oscillations ), at high frequencies it shows a highly anomalous response when compare to ordinary metals.
we present results from our giant metrewave radio telescope ( gmrt )  observations of the interacting pair arp 202 ( ).       galaxies : spiral - galaxies : interactions - galaxies : kinematics and dynamics - galaxies : individual : arp 202 - radio lines : galaxies
the surface magnetic phase transition of a double - exchange model for metallic manganites is studied using a schwinger - boson mean - field method.   about three unit - cells wide surface layers are identified.   the magnetic moment in these layers decreases more rapidly than that in the bulk when the temperature is increased.   this behavior is consistent with experimental observations.   we also discuss the implication of this behavior on the tunneling magnetoresistance effect using manganites and possible improvement of the magnetoresistance effect near the bulk curie temperature.
we study fundamental optical gap solitons in the model of a fiber bragg grating ( bg ), which is subjected to a periodic modulation of the local reflectivity, giving rise to a supergrating.   in addition, the local refractive index is also periodically modulated with the same period.   it is known that the supergrating opens an infinite system of new bandgaps in the bg s spectrum.   we use a combination of analytical and computational methods to show that each emerging bandgap is filled with gap solitons ( gss ), including asymmetric ones and bound states of the gss.   in particular, bifurcations of the gss created by the supergrating are studied in terms of a geometric analysis.   gap soliton, supergrating, homoclinic orbit, melnikov method, averaging method
we present an analysis of _ bepposax _ observations of three clusters of galaxies which are amongst the most luminous in the universe : rxj1347 - 1145, zwicky  3146 and abell  2390. using data from both the low energy ( lecs ) and medium energy ( mecs ) concentrator spectrometers, and a joint analysis with the phoswich detection system ( pds ) data above 10 kev, we constrain, with a relative uncertainty of between 7 and 42 per cent ( 90 per cent confidence level ), the mean gas temperature in the three clusters.   these measurements are checked against any possible non - thermal contribution to the plasma emission and are shown to be robust.   we confirm that rxj1347 - 1145 has a gas temperature that lies in the range between 13.2 and 22.3 kev at the 90 per cent confidence level, and is larger than 12.1 kev at @xmath0 level.   the existence of such a hot galaxy cluster at redshift of about 0.45 implies an upper limit on the mean mass density in the universe, @xmath1, of 0.5.    combining the _ bepposax _ estimates for gas temperature and luminosity of the three clusters presented in this work with _ asca _   measurements available in the literature, we obtain a slope of 2.7 in the @xmath2 relation once the physical properties are corrected from the contamination from the central cooling flows.   = 6truein    galaxies : clustering  x - ray : galaxies.
the quantum dynamics of quasi - one - dimensional ring with varying electron filling factor is investigated in presence of external electric field.   the system is modeled within hubbard hamiltonian with attractive coulomb correlation, which results in superconducting ground state when away from half - filling.   the electric field is induced by applying time - dependent aharonov - bohm flux in the perpendicular direction. to explore the non - equilibrium phenomena arising from the field,   we adopt exact diagonalization and crank - nicolson numerical method. with increase in electric field strength, the electron pairs,   a signature of superconducting phase, start breaking and the system enters into a metallic phase.   however, the strength of the electric field for this quantum phase transition depends on the electronic correlation.   this phenomenon has been confirmed by flux - quantization of time - dependent current and pair correlation functions.
tus is the world s first orbital detector of extreme energy cosmic rays ( eecrs ), which operates as a part of the scientific payload of the lomonosov satellite since may 19, 2016.   tus employs the nocturnal atmosphere of the earth to register ultraviolet ( uv ) fluorescence and cherenkov radiation from extensive air showers generated by eecrs as well as uv radiation from lightning strikes and transient luminous events, micro - meteors and space debris.   the first months of its operation in orbit have demonstrated an unexpectedly rich variety of uv radiation in the atmosphere.   we briefly review the design of tus and present a few examples of events recorded in a mode dedicated to registering eecrs.
variations in the solar wind density introduce variable delays into pulsar timing observations.   current pulsar timing analysis programs only implement simple models of the solar wind, which not only limit the timing accuracy, but can also affect measurements of pulsar rotational, astrometric and orbital parameters.   we describe a new model of the solar wind electron density content which uses observations from the wilcox solar observatory of the solar magnetic field.   we have implemented this model into the tempo2 pulsar timing package.   we show that this model is more accurate than previous models and that these corrections are necessary for high precision pulsar timing applications.
we present yang  baxter maps associated to elliptic curves.   they are related to discrete versions of the krichever - novikov and the landau - lifshits equations.   a lifting of scalar integrable quad  graph equations to two  field equations is also shown.
this paper reports on a study in which a novel virtual moving sound - based spatial auditory brain  computer interface ( bci ) paradigm is developed.   classic auditory bcis rely on spatially static stimuli, which are often boring and difficult to perceive when subjects have non  uniform spatial hearing perception characteristics.   the concept of moving sound proposed and tested in the paper allows for the creation of a p300 oddball paradigm of necessary target and non  target auditory stimuli, which are more interesting and easier to distinguish.   we present a report of our study of seven healthy subjects, which proves the concept of moving sound stimuli usability for a novel bci.   we compare online bci classification results in static and moving sound paradigms yielding similar accuracy results.   the subject preference reports suggest that the proposed moving sound protocol is more comfortable and easier to discriminate with the online bci.   * keywords : * auditory bci, p300, eeg, neurotechnology
-0.6 cm in the present contribution, we apply the double exponential sinc - collocation method ( descm ) to the one - dimensional time independent schrdinger equation for a class of rational potentials of the form @xmath0.   this algorithm is based on the discretization of the hamiltonian of the schrdinger equation using sinc expansions.   this discretization results in a generalized eigenvalue problem where the eigenvalues correspond to approximations of the energy values of the corresponding hamiltonian.   a systematic numerical study is conducted, beginning with test potentials with known eigenvalues and moving to rational potentials of increasing degree.   * ams classification : * 0.15 cm 65l10, 65l20    anharmonic oscillators.   rational potential.   sinc collocation methods. exponential transformations.
this chapter is concerned with the question : how do gravitational waves ( gws ) interact with their detectors? it is intended to be a _ theoretical review _ of the fundamental concepts involved in interferometric and acoustic ( weber bar ) gw antennas. in particular,   the type of signal the gw deposits in the detector in each case will be assessed, as well as its intensity and deconvolution.   brief reference will also be made to detector sensitivity characterisation, including very summary data on current state of the art gw detectors.
the close vicinity of neutron stars remains poorly constrained by observations.   although plenty of data are available for the peculiar class of pulsars we are still unable to deduce the underlying plasma distribution in their magnetosphere. in the present paper, we try to unravel the magnetospheric structure starting from basic physics principles and reasonable assumptions about the magnetosphere. beginning with the monopole force - free case, we compute accurate general - relativistic solutions for the electromagnetic field around a slowly rotating magnetized neutron star.   moreover, here we address this problem by including the important effect of plasma screening.   this is achieved by solving the time - dependent maxwell equations in a curved space - time following the 3 + 1  formalism.   we improved our previous numerical code based on pseudo - spectral methods in order to allow for possible discontinuities in the solution.   our algorithm based on a multi - domain decomposition of the simulation box belongs to the discontinuous galerkin finite element methods.   we performed several sets of simulations to look for the general - relativistic force - free monopole and split monopole solutions.   results show that our code is extremely powerful in handling extended domains of hundredth of light - cylinder radii  @xmath0.   the code has been validated against known exact analytical monopole solutions in flat space - time.   we also present semi - analytical calculations for the general - relativistic vacuum monopole.       gravitation - magnetic fields - plasmas - stars : neutron - methods : analytical - methods : numerical
we experimentally realize quantum hall mach - zehnder interferometer which operates far beyond the equilibrium. the operation of the interferometer is based on allowed intra - edge elastic transitions within the same landau sublevel in the regime of high imbalances between the co - propagating edge states.   since the every edge state is definitely connected with the certain landau sublevel, the formation of the interference loop can be understood as a splitting and a further reconnection of a single edge state.   we observe an aharonov - bohm type interference pattern even for low - size interferometers.   this novel interference scheme demonstrates high visibility even at millivolt imbalances and survives in a wide temperature range.
we study implications of spontaneous cp - violation in minimal susy models for cp - asymmetries in rare @xmath0-decays. in particular, we estimate characteristic values of the angles of the unitarity triangle and show that sizeable cp - violating effects result from @xmath1 mixing only.   significant deviations from the sm predictions are pointed out.   = 10000 = 12pt
the dispersion processes of aqueous samples of clay are studied using ultrasound attenuation spectroscopy.   the attenuation spectra that are acquired in the frequency range @xmath0 mhz are used to determine the particle size distributions ( psds ) for different concentrations and ages of the clay suspensions.   our analysis, using equivalent spherical diameter ( esd ) for circular discs under stokes drag in samples of concentrations greater than 1.5% w / v, shows that a substantial fraction of the aggregates in suspension are actually tactoids that are composed of more than one platelet.   this is in contrast to the general belief that clay disperses into individual platelets in the concentration range where their suspensions exhibit glassy behavior.   we conclude that the incomplete fragmentation of the clay tactoids arises from the rapid enhancement of the inter - tactoid coulombic repulsion.
we study the dynamics of an infinite regular lattice of classical charged oscillators.   each individual oscillator is described as a point particle subject to a harmonic restoring potential, to the retarded electromagnetic field generated by all the other particles, and to the radiation reaction expressed according to the lorentz   dirac equation.   exact normal mode solutions, describing the propagation of plane electromagnetic waves through the lattice, are obtained for the complete linearized system of infinitely many oscillators. at variance with all the available results,   our method is valid for any values of the frequency, or of the ratio between wavelength and lattice parameter.   a remarkable feature is that the proper inclusion of radiation reaction in the dynamics of the individual oscillators does not give rise to any extinction coefficient for the global normal modes of the lattice.   the dispersion relations resulting from our solution are numerically studied for the case of a simple cubic lattice.   new predictions are obtained in this way about the behavior of the crystal at frequencies near the proper oscillation frequency of the dipoles.
cosmogenic neutrinos@xcite are expected from ultrahigh energy cosmic rays undergoing the gzk process@xcite and anticipated to be observed by detecting air showers from the decays of tau leptons.   we use corsika simulated shower structure to calculate the coherent geosynchrotron radio emissions of the tau decay showers above @xmath0ev.   we present the pattern and spectrum of radio waves and discuss their detections by radio antennae.
using the responsible form factors calculated via full qcd, we analyze the @xmath0 transition in the standard model containing fourth generation quarks ( sm4 ).   we discuss effects of the presence of @xmath1 fourth family quark on related observables like branching ratio, forward - backward asymmetry, baryon polarization as well as double lepton polarization asymmetries.   we also compare our results with those obtained in the sm as well as with predictions of the sm4 but using form factors calculated within heavy quark effective theory. the obtained results on branching ratio indicate that the @xmath0 transition is more probable in full qcd comparing to the heavy quark effective theory.   it is also shown that the results on all considered observables in sm4 deviate considerably from the sm predictions when @xmath2.
the model dependence of the development of extensive air showers generated by high - energy cosmic - ray particles in the atmosphere is studied.   the increase of proton - proton and proton - air inelastic cross - sections and values for the elasticity are varied in the hadronic interaction model qgsjet. using the corsika simulation program,   the impact of these changes is investigated on air shower observables like the average depth of the shower maximum  and the number of muons and electrons at ground level. calculating the mean logarithmic mass from experimental  values,   it is found that a moderate logarithmic increase of the proton - proton inelastic cross - section from @xmath0  mb at @xmath1  gev to @xmath2  mb at @xmath3  gev and an elasticity, additionally increased by 10% to 15%, describes the data best. using these parameters,   the mean logarithmic mass @xmath4 derived from  measurements is compatible with the extrapolations of the results of direct measurements to high energies using the.
we study, within an effective field theory framework, @xmath0 planck - scale suppressed lorentz invariance violation ( lv ) effects in the neutrino sector, whose size we parameterize by a dimensionless parameter @xmath1.   we find deviations from predictions of lorentz invariant physics in the cosmogenic neutrino spectrum.   for positive @xmath2 coefficients no neutrino will survive above @xmath3.   the existence of this cutoff generates a bump in the neutrino spectrum at energies of @xmath4.   although at present no constraint can be cast, as current experiments do not have enough sensitivity to detect ultra - high - energy neutrinos, we show that experiments in construction or being planned have the potential to cast limits as strong as @xmath5 on the neutrino lv parameter, depending on how lv is distributed among neutrino mass states.   constraints on @xmath6 can in principle be obtained with this strategy, but they require a more detailed modeling of how lv affects the neutrino sector.
we report the discovery of two hot jupiters using photometry from campaigns 4 and 5 of the two - wheeled _ kepler _ ( k2 ) mission.   k2 - 30b has a mass of @xmath0, a radius of @xmath1 and transits its g dwarf ( @xmath2 k ), slightly metal rich ( @xmath3 dex ) host star in a 4.1 days circular orbit.   k2 - 34b has a mass of @xmath4, a radius of @xmath5 and has an orbital period of 3.0 days in which it orbits a late f dwarf ( @xmath6 k ) solar metallicity star.   both planets were confirmed via precision radial velocity ( rv ) measurements obtained with three spectrographs from the southern hemisphere.   they have physical and orbital properties similar to the ones of the already uncovered population of hot jupiters and are well - suited candidates for further orbital and atmospheric characterization via detailed follow - up observations. given that the discovery of both systems was recently reported by other groups we take the opportunity of refining the planetary parameters by including the rvs obtained by these independent studies in our global analysis.
in this paper, we seek to model the deformation of nucleated cells by single diode - laser bar optical stretchers.   we employ a recently developed computational model, the dynamic ray - tracing method, to determine the stress distribution induced by the applied optical forces on a capsule encapsulating a nucleus of different optical properties.   these forces are shape dependent and can deform real non - rigid objects ; thus resulting in a dynamically changing optical stress distribution with cell and nucleus deformation.   chinese hamster ovary cell is a common biological cell that is of interest to the biomedical community because of their use in recombinant protein therapeutics and is an example of a nucleated cell. to this end  , we model chinese hamster ovary cells as two three - dimensional elastic capsules of variable inner capsule size immersed in a fluid where the hydrodynamic forces are calculated using the immersed boundary method.   our results show that the presence of a nucleus has a major effect on the force distribution on the cell surface and the net deformation. scattering and gradient forces are reported for different nucleus sizes and the effect of nucleus size on the cell deformation is discussed.   +     + _fjoshua1@umbc.edu_ +     + _dmarr@mines.edu_ +
the deformation of a nucleon embedded in various finite nuclei is considered by taking into account the distortion of the chiral profile functions under the action of an external field representing the nuclear density.   the baryon charge distribution of the nucleon inside light, medium  heavy and heavy nuclei is discussed.   the mass of the nucleon decreases as it is placed deeper inside the nucleus and reaches its minimum at the center of the nucleus.   we discuss the quantization of non - spherical solitons and its consequences for the mass splitting of the @xmath0 states.   we show that bound nucleons acquire an intrinsic quadrupole moment due to the deformation effects.   these effects are maximal for densities of nuclei about @xmath1.   we also point out that scale changes of the electromagnetic radii can not simply be described by an overall swelling factor.   23.5 cm 2.cm -2 cm 0.46 cm 0.46 cm = 0.1 true cm
flows around a wedge - shaped bow are simulated with the aim of investigating the wave breaking mechanism and small scale features of ship bow waves.   this fluid dynamics video shows the plunging wave breaking process around the wedge including the thin water sheet formation, overturning sheet with surface disturbance, fingering and breaking up into spray, plunging and splashing, and air entrainment.
we consider a stochastic sis infection model for a population partitioned into @xmath0 households assuming random mixing.   we solve the model in the limit @xmath1 by using the self - consistent field method of statistical physics.   we derive a number of explicit results, and give numerical illustrations.   we then do numerical simulations of the model for finite @xmath0 and without random mixing.   we find in many of these cases that the self - consistent field method is a very good approximation.   sis epidemic, households, stochastic models, statistical physics
accretion onto the massive black hole at the centre of a galaxy can feed energy and momentum into its surroundings via radiation, winds and jets.   feedback due to radiation pressure can lock the mass of the black hole onto the @xmath0 relation, and shape the final stellar bulge of the galaxy.   feedback due to the kinetic power of jets can prevent massive galaxies greatly increasing their stellar mass, by heating gas which would otherwise cool radiatively.   the mechanisms involved in cosmic feedback are discussed and illustrated with observations.
we derive the theoretical red edge of the pulsating gw vir stars by using full evolutionary calculations that involve mass loss and diffusion.   we put the emphasis on the fact that the specific mass loss law used in the evolutionary computations determines the red edge s position. by combining this specific property with the observed location of the red edge in the effective temperature - surface gravity domain, we obtain interesting constraints on possible mass loss laws for pg 1159 stars.
the thirty years old programme of griffiths and harris of understanding higher - dimensional analogues of poncelet - type problems and synthetic approach to higher genera addition theorems has been settled and completed in this paper. starting with the observation of the billiard nature of some classical constructions and configurations, we construct _ the billiard algebra _, that is a group structure on the set @xmath0 of lines simultaneously tangent to @xmath1 quadrics from a given confocal family in the @xmath2-dimensional euclidean space. using this tool,   the related results of reid, donagi and knrrer are further developed, realized and simplified.   we derive a fundamental property of @xmath0 : any two lines from this set can be obtained from each other by at most @xmath1 billiard reflections at some quadrics from the confocal family.   we introduce two hierarchies of notions : _   @xmath3-skew lines _ in @xmath0 and _ @xmath3-weak poncelet trajectories _, @xmath4.   the interrelations between billiard dynamics, linear subspaces of intersections of quadrics and hyperelliptic jacobians developed in this paper enabled us to obtain higher - dimensional and higher - genera generalizations of several classical genus @xmath5 results : cayley s theorem, weyr s theorem, griffiths - harris theorem and darboux theorem.   mathematical institute sanu    kneza mihaila 36, 11000 belgrade, serbia    e - mail : vladad@mi.sanu.ac.yu, milena@mi.sanu.ac.yu    the corresponding author :    vladimir dragovi    mathematical institute sanu    kneza m
hadron - nucleus amplitudes at high energies are studied in the `` toy '' regge model in zero transverse dimension for finite nuclei, when the standard series of fan diagrams is converted into a finite sum and looses physical sense at quite low energies.   taking into account all the loop contributions by numerical methods we find a physically meaningful amplitudes at all energies.   they practically coincide with the amplitudes for infinite nuclei.   a surprizing result is that for finite nuclei and small enough triple pomeron coupling the infinite series of fan diagrams describes the amplitude quite well in spite of the fact that in reality the series should be cut and as such deprived of any physical sense at high energies.
charge ordering behavior is observed in the crystal prepared through the immersion of the @xmath0 crystal in distilled water.   discovery of the charge ordering in the crystal with na content less than 0.5 indicates that the immersion in water brings about the reduction of the @xmath0.   the formal valence of co changes from + 3.59 estimated from the na content to + 3.50, the same as that in @xmath1.   the charge compensation is confirmed to arise from the intercalation of the oxonium ions as occurred in the superconducting sodium cobalt oxide bilayer - hydrate.@xcite the charge ordering is the same as that observed in @xmath1.   it suggests that the co valence of + 3.50 is necessary for the charge ordering.
resonant dipole - dipole interaction modifies the energy and decay rate of electronic excitations for finite one dimensional chains of ultracold atoms in an optical lattice.   we show that collective excited states of the atomic chain can be divided into dark and bright modes, where a superradiant mode with an enhanced collective effective dipole dominates the optical scattering. studying the generic case of two chain segments of different length and position exhibits an interaction blockade and spatially structured light emission. ultimately, an extended system of several interfering segments models a long chain with randomly distributed defects of vacant sites.   the corresponding emission pattern provides a sensitive tool to study structural and dynamical properties of the system.
we study theoretically and experimentally the electronic relaxation of no@xmath0 molecules excited by absorption of one @xmath1 400 nm pump photon.   semi - classical simulations based on trajectory surface hopping calculations are performed.   they predict fast oscillations of the electronic character around the intersection of the ground and first excited diabatic states.   an experiment based on high - order harmonic transient grating spectroscopy reveals dynamics occuring on the same timescale. a systematic study of the detected transient is conducted to investigate the possible influence of the pump intensity, pump wavelength, and rotational temperature of the molecules.   the quantitative agreement between measured and predicted dynamics shows that, in no@xmath0, high harmonic transient grating spectroscopy encodes vibrational dynamics underlying the electronic relaxation.
these lecture notes discuss several topics in the physics of cosmic structure formation starting from the evolution of small - amplitude fluctuations in the radiation - dominated era.   the topics include relativistic cosmological perturbation theory with the scalar - vector - tensor decomposition, the evolution of adiabatic and isocurvature initial fluctuations, microwave background anisotropy, spatial and angular power spectra, the cold dark matter linear transfer function, press - schechter theory, and a brief introduction to numerical simulation methods.
we report simulations of a frustrated odd - numbered macrospin ring system, with full point dipolar interactions, driven by a rotating uniform applied magnetic field of constant magnitude.   the system is designed with equally - spaced radially - aligned macrospins, which must carry a frustrated soliton defect in its ground state.   it is shown how correctly tuning the applied field magnitude can allow for non - trivial unidirectional propagation of the soliton, the required directional pressure acquired via the curvature of the ring.   furthermore, the system, which may be employed as a multiple rotation counter, is tested for robustness against quenched disorder as would be present in an experimental realization.
to understand an aperiodic tiling ( or a quasicrystal modeled on an aperiodic tiling ), we construct a space of similar tilings, on which the group of translations acts naturally.   this space is then an ( abstract ) dynamical system.   dynamical properties of the space ( such as mixing, or the spectrum of the translation operator ) are closely related to bulk properties of individual tilings ( such as the diffraction pattern ).   the topology of the space of tilings, particularly the cech cohomology, gives information on how original tiling may be deformed.   tiling spaces can be constructed as inverse limits of branched manifolds.
the conventional wisdom for the formation of the first hard binary in core collapse is that three - body interactions of single stars form many soft binaries, most of which are quickly destroyed, but eventually one of them survives.   we report on direct n - body simulations to test these ideas, for the first time.   we find that both assumptions are often incorrect : 1 ) quite a few three - body interactions produce a hard binary from scratch ; 2 ) and in many cases there are more than three bodies directly and simultaneously involved in the production of the first binary.   the main reason for the discrepancies is that the core of a star cluster, at the first deep collapse, contains typically only five or so stars.   therefore, the homogeneous background assumption, which still would be reasonable for, say, 25 stars, utterly breaks down. there have been some speculations in this direction, but we demonstrate this result here explicitly, for the first time.   ,   , &    stellar dynamics, method : @xmath0-body simulation, globular clusters : general
the recent data for bose - einstein correlations ( bec ) of three - charged particles obtained by na44 collaboration have been analysed using theoretical formula with coulomb wave functions.   it has been recently proposed by alt et al.   it turns out that there are discrepancies between these data and the respective theoretical values. to resolve this problem we seek a possibly modified theoretical formulation of this problem by introducing the degree of coherence for the exchange effect due to the bec between two - identical bosons. as a result   we obtain a modified formulation for the bec of three - charged particles showing good agreement with the data.   moreover, we investigate physical connection between our modified formulation and the core - halo model proposed by csrg et al.   our study indicates that the interaction region estimated by the bec of three - charged particles in the s + pb collisions at 200 gev / c per nucleon is equal to about 1.5 @xmath01.8 fm.   bose - einstein correlation, three - charged particles, coulomb wave functions, high energy heavy - ion collisions
research on the core of medium and high z clusters of galaxies can derive great benefits from integral field spectroscopy, and a key role in this respect will be played by the integral field unit ( ifu ) being developed by the virmos consortium as part of the vimos spectrograph. after a brief technical outline of the instrument, some of the problems to be addressed by data reduction techniques are described, and the scientific issues to which vimos ifu is likely to give its major contribution are pointed out.
in this work we study wave propagation in dissipative relativistic fluids described by a simplified set of the 2nd order viscous conformal hydrodynamic equations corresponding to israel - stewart theory.   small amplitude waves are studied within the linearization approximation while waves with large amplitude are investigated using the reductive perturbation method, which is generalized to the case of 2nd order relativistic hydrodynamics.   our results indicate the presence of a `` soliton - like '' wave solution in israel - stewart hydrodynamics despite the presence of dissipation and relaxation effects.
we present first results of the non - linear evolution of rotating relativistic stars obtained with an axisymmetric relativistic hydrodynamics code in a fixed spacetime. as initial data we use stationary axisymmetric and perturbed configurations.   we find that, in order to prevent ( numerical ) angular momentum loss at the surface layers of the star a high - resolution grid ( or a numerical scheme that retains high order at local extrema ) is needed. for non - rotating stars, we compute frequencies of radial and non - radial small - amplitude oscillations, which are in excellent agreement with linear normal mode frequencies computed in the cowling approximation. as a first application of our code,   quasi - radial modes of rapidly rotating relativistic stars are computed. by generalizing our numerical code to 3-d  , we plan to study the evolution and non - linear dynamics of toroidal oscillations ( @xmath0-modes ) of rapidly rotating neutron stars, which are a promising source of gravitational waves.    22
this paper studies two related questions in high energy onium - onium scattering : the probability of producing an unusually large number of particles in a collision, where it is found that the cross section for producing a central multiplicity proportional to @xmath0 should decrease exponentially in @xmath1.   secondly, the nature of gluon ( dipole ) evolution when dipole densities become so high that saturation effects due to dipole - dipole interactions become important : measures of saturation are developed to help understand when saturation becomes important, and further information is obtained by exploiting changes of frame, which interchange unitarity and saturation corrections.   cu - tp-746 + cavendish - hep-96/04 + hep - ph/9605302 + may 1996    * large multiplicity fluctuations and saturation effects in onium collisions *    * * a.h.   mueller * * + _ department of physics, columbia university, _ + _ new york, ny  10027, usa _ +    * * g.p.  salam * * +    _ cavendish laboratory, cambridge university, _ + _ madingley road, cambridge cb3 0he, uk _   + e - mail : salam@hep.phy.cam.ac.uk
by evaporating a drop of lipid dispersion we generate the myelin morphology often seen in dissolving surfactant powders.   we explain these puzzling nonequilibrium structures using a geometric argument : the bilayer repeat spacing increases and thus the repulsion between bilayers decreases when a multilamellar disk is converted into a myelin without gain or loss of material and with number of bilayers unchanged.   sufficient reduction in bilayer repulsion can compensate for the cost in curvature energy, leading to a net stability of the myelin structure.   a numerical estimate predicts the degree of dehydration required to favor myelin structures over flat lamellae.
a novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. to overcome the mechanical challenges of construction,   an innovative light collection geometry has been pioneered, that minimises the complexity of construction.   first test results are presented, demonstrating a successful signal extraction.   the geometry consists of a sampling calorimeter with passive absorber layers interleaved with layers of an active medium made of inorganic scintillating crystals.   wavelength - shifting ( wls ) fibres run along the four long, chamfered edges of the stack, transporting the light to photodetectors at the rear. to maximise the amount of scintillation light reaching the wls fibres  , the scintillator chamfers are depolished.   it is shown herein that this concept is working for cerium fluoride ( cef@xmath0 ) as a scintillator.   coupled to it, several different types of materials have been tested as wls medium.   in particular, materials that might be sufficiently resistant to the high - luminosity large hadron collider radiation environment, such as cerium - doped lutetium - yttrium orthosilicate ( lyso ) and cerium - doped quartz, are compared to conventional plastic wls fibres.   finally, an outlook is presented on the possible optimisation of the different components, and the construction and commissioning of a full calorimeter cell prototype is presented.   r. becker, g. dissertori, a. gendotti, q. huang, d. luckey, w.  lustermann, s. lutterer, +, f. pandolfi, f. pauss, m. peruzzi, m. quittnat, r.  wallny
we introduce pseudocubical objects with pseudoconnections in an arbitrary category, obtained from the brown - higgins structure of a cubical object with connections by suitably relaxing their identities, and construct a cubical analog of the tierney - vogel theory of simplicial derived functors. the crucial point in the construction   is that projective precubical resolutions which are naturally used to define our cubical derived functors possess pseudodegeneracies and pseudoconnections.   the same fact is essentially used for proving that in the case of an additive functor between abelian categories, our theory coincides with the classical relative theory of derived functors by eilenberg - moore.
we introduce a theoretical framework which is suitable for the description of all spatial and time - multiplexed periodic single - photon sources realized or proposed thus far.   our model takes into account all possibly relevant loss mechanisms.   this statistical analysis of the known schemes shows that multiplexing systems can be optimized in order to produce maximal single - photon probability for various sets of loss parameters by the appropriate choice of the number of multiplexed units of spatial multiplexers or multiplexed time intervals and the input mean photon pair number, and reveals the physical reasons of the existence of the optimum.   we propose a novel time - multiplexed scheme to be realized in bulk optics, which, according to the present analysis, would have promising performance when experimentally realized.   it could provide a single - photon probability of 85% with a choice of experimental parameters which are feasible according to the experiments known from the literature.
we examine two members of the ngc 4065 group of galaxies : a bent - double ( a.k.a.   wide angle tail ) radio source and an deficient spiral galaxy.   models of the x - ray emitting intragroup gas and the bent - double radio source, ngc 4061, are used to probe the density of intergalactic gas in this group.   observations reveal an asymmetric, truncated distribution of in spiral galaxy, ugc 07049, and the accompanying radio continuum emission reveals strong star formation.   we examine the effectiveness of ram pressure stripping as a gas removal mechanism and find that it alone can not account for the deficiency that is observed in ugc 07049 unless this galaxy has passed through the core of the group with a velocity of @xmath0.   a combination of tidal and ram pressure stripping are necessary to produce the deficiency and asymmetry in this galaxy.       galaxies : groups : individual : ngc 4065  intergalactic medium  galaxies ; jets  galaxies : evolution
we present a new mechanism for the ejection of a common envelope in a massive binary, where the energy source is nuclear energy rather than orbital energy.   this can occur during the slow merger of a massive primary with a secondary of @xmath0m@xmath1 when the primary has already completed helium core burning.   we show that, in the final merging phase, hydrogen - rich material from the secondary can be injected into the helium - burning shell of the primary.   this leads to a nuclear runaway and the explosive ejection of both the hydrogen and the helium layer, producing a close binary containing a co star and a low - mass companion.   we argue that this presents a viable scenario to produce short - period black - hole binaries and long - duration gamma - ray bursts ( lgrbs ).   we estimate a lgrb rate of @xmath2yr@xmath3 at solar metallicity, which implies that this may account for a significant fraction of all lgrbs, and that this rate should be higher at lower metallicity.       black holes  binaries : general  gamma - rays : bursts  stars : individual : x - ray nova sco  x - rays : stars.
under the assumption that the density variation of the electrons can be approximated by an exponential function, the solar mikheyev - smirnov - wolfenstein effect is treated for three generations of neutrinos.   the generalized hypergeometric functions that result from the exact solution of this problem are studied in detail, and a method for their numerical evaluation is presented.   this analysis plays a central role in the determination of neutrino masses, not only the differences of their squares, under the assumption of universal quark - lepton mixing.   cern - th/99 - 286 + december 1999
we present an optical imaging study of 20 southern - sky nova remnants which has resulted in the discovery of four previously unknown nova shells  v842 cen, rr cha, dy pup and hs pup.   the study has also revealed previously unobserved features in three other known shells   those of bt mon, cp pup and rr pic.   the images of bt mon, v842 cen, rr cha, dy pup and hs pup have been processed using several deconvolution algorithms ( richardson - lucy, maximum entropy and clean ) in addition to straightforward point - source subtraction in an attempt to resolve the shells from the central stars.   the use of four different methods enables us to make a qualitative judgement of the results.   notably, the shell of rr pic displays tails extending outwards from clumps in the main ejecta similar to those previously detected in dq her.   novae, cataclysmic variables  circumstellar matter  techniques : image processing
gauge higgs unification in warped extra dimensions provides an attractive solution to the hierarchy problem.   the extension of the standard model gauge symmetry to @xmath0 allows the incorporation of the custodial symmetry @xmath1 plus a higgs boson doublet with the right quantum numbers under the gauge group. in the minimal model,   the higgs mass is in the range 110150  gev, while a light kaluza klein ( kk ) excitation of the top quark appears in the spectrum, providing agreement with precision electroweak measurements and a possible test of the model at a high luminosity lhc.   the extension of the model to the lepton sector has several interesting features.   we discuss the conditions necessary to obtain realistic charged lepton and neutrino masses.   after the addition of an exchange symmetry in the bulk, we show that the odd neutrino kk modes provide a realistic dark matter candidate, with a mass of the order of 1  tev, which will be probed by direct dark matter detection experiments in the near future.
quantum gaussian states can be considered as the majority of the practical quantum states used in quantum communications and more generally in quantum information.   here we consider their properties in relation with the geometrically uniform symmetry, a property of quantum states that greatly simplifies the derivation of the optimal decision by means of the square root measurements. in a general framework of the @xmath0-mode gaussian states we show the general properties of this symmetry and the application of the optimal quantum measurements.   an application example is presented, to quantum communication systems employing pulse position modulation.   we prove that the geometrically uniform symmetry can be applied to the general class of multimode gaussian states.
we simulate the formation of cosmic strings at the zeros of a complex gaussian field with a power spectrum @xmath0, specifically addressing the issue of the fraction of length in infinite strings.   we make two improvements over previous simulations : we include a non - zero random background field in our box to simulate the effect of long - wavelength modes, and we examine the effects of smoothing the field on small scales.   the inclusion of the background field significantly reduces the fraction of length in infinite strings for @xmath1.   our results are consistent with the possibility that infinite strings disappear at some @xmath2 in the range @xmath3, although we can not rule out @xmath4, in which case infinite strings would disappear only at the point where the mean string density goes to zero.   we present an analytic argument which suggests the latter case.   smoothing on small scales eliminates closed loops on the order of the lattice cell size and leads to a  lattice - free " estimate of the infinite string fraction.   as expected, this fraction depends on the type of window function used for smoothing.    *   x**x * # 1#2#3#4    = # 4 in
the _ herschel _ multi - tiered extragalactic survey ( hermes ) is the largest guaranteed time key programme on the _ herschel _ space observatory. with a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling @xmath0380 deg@xmath1. in this paper, we present deep point source catalogues extracted from _   herschel_-spire observations of all hermes fields, except for the later addition of the 270 deg@xmath1 helms field.   these catalogues constitute the second data release ( dr2 ) made in october 2013. a subset of these catalogues, which consists of bright sources extracted from _   herschel_-spire observations completed by may 1, 2010 ( covering @xmath0 74 deg@xmath1 ) were released earlier in the first extensive data release ( dr1 ) in march 2012.   two different methods are used to generate the point source catalogues, the sussextractor ( sxt ) point source extractor used in two earlier data releases ( edr and edr2 ) and a new source detection and photometry method.   the latter combines an iterative source detection algorithm, starfinder ( sf ), and a de - blended spire photometry ( desphot ) algorithm.   we use end - to - end _   herschel_-spire simulations with realistic number counts and clustering properties to characterise basic properties of the point source catalogues, such as the completeness, reliability, photometric and positional accuracy. over 500, 000 catalogue entries in hermes fields ( except helms ) are released to the public through the hedam website ( http://hedam.oamp.fr/hermes ).
we apply the frozen density embedding method, using a full relaxation of embedded densities through a freeze - and - thaw procedure, to study the electronic structure of several benchmark ground - state charge - transfer complexes, in order to assess the merits and limitations of the approach for this class of systems.   the calculations are performed using both semilocal and hybrid exchange - correlation ( xc ) functionals.   the results show that embedding calculations using semilocal xc functionals yield rather large deviations with respect to the corresponding supermolecular calculations. due to a large error cancellation effect,   however, they can often provide a relatively good description of the electronic structure of charge - transfer complexes, in contrast to supermolecular calculations performed at the same level of theory. on the contrary, when hybrid xc functionals are employed, both embedding and supermolecular calculations agree very well with each other and with the reference benchmark results.    in conclusion, for the study of ground - state charge - transfer complexes via embedding calculations hybrid   xc functionals are the method of choice due to their higher reliability and superior performance.
i study the formation of comptonization spectra in spherically symmetric, fast moving media in a flat spacetime.   i analyze the mathematical character of the moments of the transfer equation in the system - frame and describe a numerical method that provides fast solutions of the time - independent radiative transfer problem that are accurate in both the diffusion and free - streaming regimes.   i show that even if the flows are mildly relativistic ( @xmath0, where @xmath1 is the electron bulk velocity in units of the speed of light ), terms that are second - order in @xmath1 alter the emerging spectrum both quantitatively and qualitatively. in particular, terms that are second - order in @xmath1   produce power - law spectral tails, which are the dominant feature at high energies, and therefore can not be neglected.   i further show that photons from a static source are upscattered by the bulk motion of the medium even if the velocity field does not converge.   finally, i discuss these results in the context of radial accretion onto and outflows from compact objects.
we present preliminary results of a simultaneous x - ray / optical campaign of the prototypical lmxb sco x-1 at 1 - 10 hz time resolution.   lightcurves of the high excitation bowen / heii emission lines were obtained through narrow interference filters with ultracam, and these were cross - correlated with x - ray lightcurves.   we find evidence for correlated variability, in particular when sco x-1 enters the flaring branch.   the bowen / heii lightcurves lag the x - ray lightcurves with a light travel time which is consistent with reprocessing in the companion star.   address = instituto de astrofsica de canarias, 38200 la laguna, tenerife, spain     address = instituto de astrofsica de canarias, 38200 la laguna, tenerife, spain     address = instituto de astrofsica de canarias, 38200 la laguna, tenerife, spain     address = school of physics & astronomy, univ. of southampton, southampton sob17 1bj, uk     address = school of physics & astronomy, univ. of southampton, southampton sob17 1bj, uk   address = dept. of physics,   univ. of warwick, coventry cv4 7al,   uk     address = dept. of physics & astronomy, univ. of sheffield, sheffield s3 7rh, uk   address = harvard - smithsonian center for astrophysics, cambridge ma 02138, usa
it is well known that pulse - like solutions of the cubic complex ginzburg - landau equation are unstable but can be stabilised by the addition of quintic terms. in this paper   we explore an alternative mechanism where the role of the stabilising agent is played by the parametric driver.   our analysis is based on the numerical continuation of solutions in one of the parameters of the ginzburg - landau equation ( the diffusion coefficient @xmath0 ), starting from the nonlinear schrdinger limit ( for which @xmath1 ).   the continuation generates, recursively, a sequence of coexisting stable solutions with increasing number of humps. the sequence   converges " to a long pulse which can be interpreted as a bound state of two fronts with opposite polarities.
we describe the la silla - quest ( lsq ) variability survey.   lsq is a dedicated wide field synoptic survey in the southern hemisphere, focusing on the discovery and study of transients ranging from low redshift ( z @xmath0 0.1 ) sn ia, tidal disruption events, rr lyrae variables, cvs, quasars, tnos and others.   the survey utilizes the 1.0-m schmidt telescope of the european southern observatory at la silla, chile with the large area quest camera, a mosaic of 112 ccd s with field of view of 9.6 square degrees.   the lsq survey was commissioned in 2009, and is now regularly covering  1000 square deg per night with a repeat cadence of hours to days.   the data are currently processed on a daily basis.   we present here a first look at the photometric capabilities of lsq and we discuss some of the most interesting recent transient detections.
a new type of the graphene - based three - port circulator is suggested and analysed.   the cross - section of the component presents a three - layer structure consisting of a layer of silicon, of silica and of graphene.   in - plane figure resembles a common microwave nanostrip circulator with a circular graphene resonator and three waveguides symmetrically connected to it.   the graphene is magnetized normally to its plane by a dc magnetic field.   the numerical simulation demonstrates the isolation of -15 db and insertion losses of -2 db in 6.98 % frequency band with the central frequency 8.23thz.
two new families of exact solutions to the einstein equations for a conformastatic spacetime with axial symmetry are presented which describe thin disks of dust immersed in a spheroidal halo.   the solutions are obtained by expressing the metric function in terms of an auxiliary function which satisfies the laplace equation, a characteristic property of the conformastatic spacetimes.   the first family of solutions is obtained from the displacement, cut and reflexion method, which introduces a discontinuity in the first @xmath0-derivate of the metric tensor across the plane of the disk.   the second family of solutions is obtained by using the oblate spheroidal coordinates because they adapt to the shape of the source and introduce naturally a cutting radius for the disk.   the energy densities of the disk and the halo are everywhere positive and well behaved and their energy - momentum tensor agrees with all the energy conditions.   some particular solutions for the energy density of the disk and the halo are presented and the rotational curves are obtained by solving the geodesic equation for a particle that moves in circular orbits in the plane of the disk.
we analyze the dynamical scaling behavior in a two - dimensional spin model with competing interactions after a quench to a striped phase.   we measure the growth exponents studying the scaling of the interfaces and the scaling of the shrinking time of a ball of one phase plunged into the sea of another phase.   our results confirm the predictions found in previous papers.   the correlation functions measured in the direction parallel and transversal to the stripes are different as suggested by the existence of different interface energies between the ground states of the model.   our simulations show anisotropic features for the correlations both in the case of single - spin - flip and spin - exchange dynamics.   # 1#2 # 1#2    # # 1##2#2##1
we have used long - baseline near - ir interferometry to resolve the peculiar eruptive variable v838 mon and to provide the first direct measurement of its angular size. assuming a uniform disk model for the emission we derive an apparent angular diameter at the time of observations ( november - december 2004 ) of @xmath0 milli - arcseconds. for a nominal distance of @xmath1 kpc, this implies a linear radius of @xmath2. however, the data are somewhat better fit by elliptical disk or binary component models, and we suggest that the emission may be strongly affected by ejecta from the outburst.
we present measurements of airborne fission products in chapel hill, nc, usa, from 62 d following the march 11, 2011, accident at the fukushima dai - ichi nuclear power plant.   airborne particle samples were collected daily in air filters and radio - assayed with two high - purity germanium ( hpge ) detectors.   the fission products ^131^i and ^137^cs were measured with maximum activity concentrations of 4.2 @xmath0 0.6 mbq / m^3^ and 0.42 @xmath0 0.07 mbq / m^3^ respectively.   additional activity from ^131,132^i, ^134,136,137^cs and ^132^te were measured in the same air filters using a low - background hpge detector at the kimballton underground research facility ( kurf ).    radioactive fallout, fukushima nuclear accident, fission product radionuclides, gamma spectroscopy
the study of collective decision making system has become the central part of the swarm - intelligence related research in recent years.   the most challenging task of modelling a collective decision making system is to develop the macroscopic stochastic equation from its microscopic model. in this report   we have investigated the behaviour of a collective decision making system with specified microscopic rules that resemble the chemical reaction and used different group size.   then we ventured to derive a generalized analytical model of a collective - decision system using hyper - geometric distribution. + index terms-_swarm _ ; _ collective decision making _ ; _ noise _ ; _ group size _ ; _ hyper - geometric distribution _
we introduce a general range of science drivers for using the virtual observatory ( vo ) and identify some common aspects to these as well as the advantages of vo data access.   we then illustrate the use of existing vo tools to tackle multi wavelength science problems.   we demonstrate the ease of multi mission data access using the voexplorer resource browser, as provided by astrogrid ( http://www.astrogrid.org ) and show how to pass the various results into any vo enabled tool such as topcat for catalogue correlation.   voexplorer offers a powerful data - centric visualisation for browsing and filtering the entire vo registry using an itunes type interface.   this allows the user to bookmark their own personalised lists of resources and to run tasks on the selected resources as desired.   we introduce an example of how more advanced querying can be performed to access existing x - ray cluster of galaxies catalogues and then select extended only x - ray sources as candidate clusters of galaxies in the 2xmmi catalogue.   finally we introduce scripted access to vo resources using python with astrogrid and demonstrate how the user can pass on the results of such a search and correlate with e.g. optical datasets such as sloan.   hence we illustrate the power of enabling large scale data mining of multi wavelength resources in an easily reproducible way using the vo.
systematic simulations are carried out based on the model of fluidized beds proposed by the present authors [ k.ichiki and h.hayakawa, phys.   rev.   e * 52 *, 658 ( 1995 ) ]. from our simulation  , we confirm that fluidization is a continuous transition.   we also confirm the existence of two types of fluidized phases, the channeling phase and the bubbling phase.   we find the close relations between the averaged behaviors in fluidized beds and quasi equilibrium states in dense liquids. in fluidized beds,   ( i ) the flow rate plays the role of the effective temperature, and ( ii ) the existence of a kind of the fluctuation - dissipation relation is suggested.
new galex observations have detected significant fuv ( 1530 ) and nuv ( 2310 ) emission from stellar substructures within the tidal tails of four ongoing galaxy mergers.   the uv - bright regions are optically faint and are coincident with hi density enhancements.   fuv emission is detected at any location where the hi surface density exceeds @xmath0 2 m@xmath1 pc@xmath2, and is often detected in the absence of visible wavelength emission.   uv luminosities of the brighter regions of the tidal tails imply masses of 10@xmath3m@xmath1 up to @xmath0 10@xmath4m@xmath1 in young stars in the tails, and hi luminosities imply similar hi masses.   uv - optical colors of the tidal tails indicate stellar populations as young as a few myr, and in all cases ages @xmath5 400myr. most of the young stars in the tails formed in single bursts rather than resulting from continuous star formation, and they formed _ in situ _ as the tails evolved.   star formation appears to be older near the parent galaxies and younger at increasing distances from the parent galaxy  . this could be because the star formation occurs progressively along the tails, or because the star formation has been inhibited near the galaxy / tail interface.   the youngest stellar concentrations, usually near the ends of long tidal tails, have masses comparable to confirmed tidal dwarf galaxies and may be newly forming galaxies undergoing their first burst of star formation.
+ coherent analyses of experimental results from lhc and ilc will allow us to draw a comprehensive and precise picture of the supersymmetric particle sector. based on this platform the fundamental supersymmetric theory   can be reconstructed at the high scale which is potentially close to the planck scale.   this procedure will be reviewed for three characteristic examples : minimal supergravity as the paradigm ; a left - right symmetric extension incorporating intermediate mass scales ; and a specific realization of string effective theories.
we study the time dependent cross correlations of stock returns, i.e. we measure the correlation as the function of the time shift between pairs of stock return time series using tick - by - tick data.   we find a weak but significant effect showing that in many cases the maximum correlation appears at nonzero time shift indicating directions of influence between the companies. due to the weakness of this effect and the shortness of the characteristic time ( of the order of a few minutes ) our findings   are compatible with market efficiency.   the interaction of companies defines a directed network of influence.
we derive first- and second - order piezoelectric coefficients for the zinc - blende iii - v semiconductors, \{al, ga, in}-\{n, p, as, sb}. the results are obtained within the heyd - scuseria - ernzerhof hybrid - functional approach in the framework of density functional theory and the berry - phase theory of electric polarization. to achieve a meaningful interpretation of the results,   we build an intuitive phenomenological model based on the description of internal strain and the dynamics of the electronic charge centers.   we discuss in detail first- and second - order internal strain effects, together with strain - induced changes in ionicity.   this analysis reveals that the relatively large importance in the iii - vs of non - linear piezoelectric effects compared to the linear ones arises because of a delicate balance between the ionic polarization contribution due to internal strain relaxation effects, and the contribution due to the electronic charge redistribution induced by macroscopic and internal strain.
we study the transport process of interacting brownian particles in a tube of varying cross section. to describe this process   we introduce a modified fick - jacobs equation, considering particles that interact through a hard - core potential.   we were able to solve the equation with numerical methods for the case of symmetric and asymmetric cavities.   we focused in the concentration of particles along the direction of the tube.   we also preformed monte carlo simulations to evaluate the accuracy of the results, obtaining good agreement between theory and simulations.
a shadow wave function ( swf ) is employed along with variational monte carlo techniques to describe the ground state properties of solid molecular para - hydrogen.   the study has been extended to densities below the equilibrium value, to obtain a parameterization of the swf useful for the description of inhomogeneous phases.   we also present an estimate of the vacancy formation energy as a function of the density, and discuss the importance of relaxation effects near the vacant site.
the quadratic gravitational lagrangian with torsion provides us with a richer number of solutions than the einstein - hilbert lagrangian does. with proper interpretation,   these solutions, together, seem to give good explanations of the form of the galactic rotation curves, of the amount of intergalactic gravitational lensings, and of the accelerating expansion of the universe.
adiabatic quantum algorithms are characterized by their run time and accuracy.   the relation between the two is essential for quantifying adiabatic algorithmic performance, yet is often poorly understood.   we study the dynamics of a continuous time, adiabatic quantum search algorithm, and find rigorous results relating the accuracy and the run time.   proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes : the error decreases exponentially for short times, then decreases polynomially for longer times.   we show that the well known quadratic speedup over classical search is associated only with the exponential error regime.   we illustrate the results through examples of evolution paths derived by minimization of the adiabatic error.   we also discuss specific strategies for controlling the adiabatic error and run time.
in this chapter we discuss the x - ray radiation from relativistic accretion disks around supermassive black holes, supposed to exist in the centers of active galactic nuclei ( agn ).   our focus is on the x - ray radiation, especially in the fe k@xmath0 line which originates in the innermost parts of an accretion disk.   moreover, here we discuss some effects which can disturb the fe k@xmath0 profile and cause its rapid and irregular variability, observed in the x - ray spectra of some agn.   we will pay attention to three such effects : perturbations in the disk emissivity, absorbtion by warm absorbers and gravitational microlensing. the x - ray emission from accretion disks around   non - rotating ( schwarzschild metric ), as well as rotating ( kerr metric ) supermassive black holes, is discussed.   the x - ray radiation of agn is probably produced in a compact region near their central supermassive black holes, and can provide us some essential information about the plasma conditions and the space - time geometry in these regions.   the goal of this chapter is mainly to present a short overview of some important and recent investigations in this field.
constructionism is a learning theory that states that we learn more when we construct tangible objects. in the process of building and presenting our work,   we make concrete the abstract mental models we ve formed, see where they breakdown through the feedback we receive, and revise the models accordingly.   computer programming has long been taught under a constructionist approach using sensory - rich contexts like robots, media, and logo - style environments. now, with affordable 3-d printers in the hands of consumers, we have a new medium in which learners may realize their computational ideas. in this demonstration, we share a mobile development environment named madeup, which empowers its users to navigate 3-d space using a logo - like imperative and functional language.   every stop in space becomes a vertex in a 3-d model.   the generated models may be exported or uploaded to a 3-d printing service.   constructionism, 3-d modeling, learning ides
we consider the task of extracting work from quantum systems in the resource theory perspective of thermodynamics, where free states are arbitrary thermal states, and allowed operations are energy conserving unitary transformations. taking as our work storage system a ` weight'  we prove the second law and then present simple protocols which extract _ average _ work equal to the free energy change of the system  the same amount as in classical thermodynamics.   crucially, for systems in ` classical'states ( mixtures of energy eigenstates ) our protocol works on a single copy of the system.   this is in sharp contrast to previous results, which showed that in case of _ almost - deterministic _ work extraction, collective actions on multiple copies are necessary to extract the free energy.   this establishes the fact that free energy is a meaningful notion even for individual systems in classical states.   however, for non - classical states, where coherences between energy levels exist, we prove that collective actions are necessary, so long as no external sources of coherence are used.
we are concerned with underlying connections between fluids, elasticity, isometric embedding of riemannian manifolds, and the existence of wrinkled solutions of the interconnected nonlinear partial differential equations. in this paper  , we develop such connections for the case of two spatial dimensions and demonstrate that the continuum mechanical equations can be mapped into a corresponding geometric framework and the inherent direct application of the theory of isometric embeddings and the gauss - codazzi equations through examples for the euler equations for fluids and the euler - lagrange equations for elastic solids.   these results show that the geometric theory provides an avenue for addressing the admissibility criteria for nonlinear conservation laws in continuum mechanics.
the large - scale structure of the magnetic field in the solar corona provides the energy to power large - scale solar eruptive events.   our physical understanding of this structure, and hence our ability to predict these events, is limited by the type of data currently available.   it is shown that the multifractal spectrum is a powerful tool to study this structure, by providing a physical connection between the details of photospheric magnetic gradients and current density at all size scales.   this uses concepts associated with geometric measure theory and the theory of weakly differentiable functions to compare ampre s law to the wavelet - transform modulus maximum method.   the hlder exponent provides a direct measure of the rate of change of current density across spatial size scales.   as this measure is independent of many features of the data ( pixel resolution, data size, data type, presence of quiet - sun data ), it provides a unique approach to studying magnetic - field complexity and hence a potentially powerful tool for a statistical prediction of solar - flare activity.   three specific predictions are provided to test this theory : the multifractal spectra will not be dependent on the data type or quality ; quiet - sun gradients will not persist with time ; structures with large current densities at large size scale will be the source of energy storage for solar eruptive events.
new scaling structure for the shadow corrections in elastic scattering from deuteron at high energies has been presented and discussed.   it is shown that this structure corresponds to the experimental data on proton(antiproton)-deuteron total cross sections.   the effect of weakening for the inelastic screening at super - high energies has been theoretically predicted.
deeply virtual compton scattering ( dvcs ) in @xmath0 collisions has emerged in recent years as a an essential reaction to obtain information on the correlation of partons in the hadron ( proton ) or on the transverse distribution of these partons. in these proceedings, we examine the lattest data from hera ( at low @xmath1 ) and their impact on models.   we analyse in detail what these data imply on the spatial structure of the proton.   in particular, the most recent measurements of the beam charge asymmetry by the h1 experiment is discussed in this context.   perspectives are presented for further measurements of dvcs cross sections at cern, within the compass experiment.
excitation of a model photosynthetic molecular aggregate by incoherent sunlight is systematically examined. for a closed system, the excited state coherence induced by the sunlight oscillates with an average amplitude that is inversely proportional to the excitonic gap, and reaches a stationary amplitude that depends on the temperature and coherence time of the radiation field. for an open system,   the light - induced dynamical coherence relaxes to a static coherence determined by the non - canonical thermal distribution resulting from the entanglement with the phonon bath.   the decay of the excited state population to the common ground state establishes a non - equilibrium steady - state flux driven by the sunlight, and it defines a time window to observe the transition from dynamical to static coherence. for the parameters relevant to photosynthetic systems,   the exciton dynamics initiated by the sunlight exhibits a non - negligible amount of dynamical coherence ( quantum beats ) on the sub - picosecond timescale ; however, this sub - picosecond time - scale is long enough for light - harvesting systems to establish static coherence, which plays a crucial role in efficient energy transfer.   further, a relationship is established between the non - equilibrium steady - state induced by the sunlight and the coherent dynamics initiated from the ground state by a laser @xmath0-pulse, thereby making a direct connection between incoherent sunlight excitation and ultrafast spectroscopy.
we analyze the light curves of the recent solar eclipses measured by the herzberg channel ( 200220 nm ) of the large yield radiometer ( lyra ) onboard proba-2.   the measurements allow us to accurately retrieve the center - to - limb variations ( clv ) of the solar brightness.   the formation height of the radiation depends on the observing angle so the examination of the clv provide information about a broad range of heights in the solar atmosphere.   we employ the 1d nlte radiative transfer code for solar irradiance ( cosi ) to model the measured light curves and corresponding clv dependencies.   the modeling is used to test and constrain the existing 1d models of the solar atmosphere, e.g. the temperature structure of the photosphere and the treatment of the pseudo - continuum opacities in the herzberg continuum range.   we show that cosi can accurately reproduce not only the irradiance from the entire solar disk, but also the measured clv.   it hence can be used as a reliable tool for modeling the variability of the spectral solar irradiance.
images at 12.5  @xmath0 m of nuclei of three nearby seyfert galaxies  ngc  1275, ngc  4151 and ngc  7469  have been obtained with the keck 10-m telescope.   ngc  7469 is resolved and deconvolution delineates a structure ( @xmath10.@xmath204  ) @xmath3  0.@xmath208 or @xmath113  @xmath3  26 pc at a position angle of 135 @xmath4. from a comparison with structure seen at millimeter wavelengths, this structure is interpreted as a disk aligned with the molecular gas in the central few hundred parsecs of the galaxy.   ngc  1275 and ngc  4151 are not resolved ; limits on the sizes of these nuclei are 008 and 016, corresponding to physical spatial scales of 28 and 10  pc.   the lower limits to the brightness temperatures implied by these size limits and the measured flux densities are within @xmath550  k of the 12  -  25  @xmath0 m color temperatures of these systems as inferred from iras observations.   the angular size limits are within a factor of 2.5 of the sizes required to spatially resolve thermal emission from dust heated by a central luminosity source.   these sizes preclude significant contributions to the nuclear infrared emission from star forming regions.
the made - to - measure @xmath0-body method @xcite slowly adapts the particle weights of an @xmath0-body model, whilst integrating the trajectories in an assumed static potential, until some constraints are satisfied, such as optimal fits to observational data.   i propose a novel technique for this adaption procedure, which overcomes several limitations and shortcomings of the original method.   the capability of the new technique is demonstrated by generating realistic @xmath0-body equilibrium models for dark - matter haloes with prescribed density profile, triaxial shape, and slowly outwardly growing radial velocity anisotropy.       stellar dynamics   methods : @xmath0-body simulations  galaxies : kinematics and dynamics  galaxies : structure  galaxies : haloes
here the role and influence of aberrations in optical imaging systems employing partially coherent complex scalar fields is studied.   imaging systems require aberrations to yield contrast in the output image. for linear shift   invariant optical systems, we develop an expression for the output cross  spectral density under the space   frequency formulation of statistically stationary partially coherent fields.   we also develop expressions for the output cross   spectral density and associated spectral density for weak  phase, weak  phase  amplitude, and single   material objects in one transverse spatial dimension.
the effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab - initio calculations.   our results show that up to 5% strain the dirac cone remains essentially at the fermi level, while higher strain induces hole doping because of weakening of the si@xmath0si bonds.   we demonstrate that the silicene lattice is stable up to 17% strain.   it is noted that the buckling first decreases with the strain ( up to 10% ) and then increases again, which is accompanied by a band gap variation.   we also calculate the grneisen parameter and demonstrate a strain dependence similar to that of graphene.
interacting galaxies like the famous antennae ( ngc  4038/4039 ) or stephan s quintet ( hcg  92 ) show considerable star forming activity in their tidal arms.   high resolution images ( e.g. from hst - observations ) indicate that these regions consist of up to hundreds of massive stellar clusters or tidal dwarf galaxies ( tdg ). in this paper   we want to investigate the future fate of these clusters of massive star clusters ( in this work called _ super - clusters _ ).   we simulate compact super - clusters in the tidal field of a host - galaxy and investigate the influence of orbital and internal parameters on the rate and timescale of the merging process.   we show that it is possible that such configurations merge and build a dwarf galaxy, which could be an important mechanism of how long - lived dwarf satellite galaxies form.   a detailed study of the merger object will appear in a follow - up paper.
we present the suzaku results of the mixed - morphology supernova remnant w28.   the x - ray spectra of the central region of w28 exhibit many bright emission lines from highly ionized atoms.   an optically thin thermal plasma in collisional ionization equilibrium, either of single - temperature or multi - temperature failed to reproduce the data with line - like and bump - like residuals at the si lyman@xmath0 energy and at 2.45.0  kev, respectively.   the bumps probably correspond to radiative recombination continua from he - like si and s. a simple recombining plasma model nicely fit the bump structures, but failed to fit low energy bands.   the overall spectra can be fit with a multi - ionization temperature plasma with a common electron temperature.   the multi - ionization temperatures are interpreted as elemental difference of ionization and recombination timescales.   these results prefer the rarefaction scenario for the origin of the recombining plasma.    [   cols="^,^,^,^,^,^ ", ]     ( 140mm,90mm)figure1.eps
this paper studies the massive mimo full - duplex relaying ( mm - fdr ), where multiple source - destination pairs communicate simultaneously with the help of a common full - duplex relay equipped with very large antenna arrays.   different from the traditional mm - fdr protocol, a general model where sources / destinations are allowed to equip with multiple antennas is considered.   in contrast to the conventional mimo system, massive mimo must be built with low - cost components which are prone to hardware impairments. in this paper, the effect of hardware impairments is taken into consideration, and is modeled using transmit / receive distortion noises.   we propose a low complexity hardware impairments aware transceiver scheme ( named as hia scheme ) to mitigate the distortion noises by exploiting the statistical knowledge of channels and antenna arrays at sources and destinations. a joint degree of freedom and power optimization algorithm   is presented to further optimize the spectral efficiency of hia based mm - fdr.   the results show that the hia scheme can mitigate the  ceiling effect " appears in traditional mm - fdr protocol, if the numbers of antennas at sources and destinations can scale with that at the relay.   massive mimo full - duplex relaying, hardware impairments, transceiver design, joint degree of freedom and power optimization, achievable rate.
we summarise applications of dyson - schwinger equations to the theory and phenomenology of hadrons.   some exact results for pseudoscalar mesons are highlighted with details relating to the @xmath0 problem.   we describe inferences from the gap equation relating to the radius of convergence for expansions of observables in the current - quark mass.   we recapitulate upon studies of nucleon electromagnetic form factors, providing a comparison of the @xmath1-weighted ratios of pauli and dirac form factors for the neutron and proton.
the inclusive @xmath0 production cross - section and fraction of @xmath0 mesons produced in @xmath1-hadron decays are measured in proton - proton collisions at @xmath2tev with the atlas detector at the lhc, as a function of the transverse momentum and rapidity of the @xmath0, using 2.3  pb@xmath3 of integrated luminosity.   the cross - section is measured from a minimum @xmath4 of 1  gev to a maximum of 70  gev and for rapidities within @xmath5 giving the widest reach of any measurement of @xmath0 production to date.   the differential production cross - sections of prompt and non - prompt @xmath0 are separately determined and are compared to colour singlet nnlo@xmath6, colour evaporation model, and fonll predictions.    * cern - ph - ep-2011 - 041 *
a sequential fourth generation of quarks and leptons is allowed by precision electroweak constraints if the mass splitting between the heavy quarks is between 50 and 80 gev.   although heavy quarks can be easily detected at the lhc, it is very difficult to detect a sequential heavy charged lepton, @xmath0, due to large backgrounds.   should the @xmath0 mass be above @xmath1 gev, it can not be pair - produced at a 500 gev ilc.   we calculate the cross section for the one - loop process @xmath2.   although the cross section is small, it may be detectable.   we also consider contributions from the two higgs doublet model and the randall - sundrum model, in which case the cross section can be substantially higher.
the gamma - ray burst of 28 february 1997 ( grb 970228 ) ushered in the discovery of the afterglow phenomenon. despite intense study of the host galaxy, however, the nature of the host and the distance to the burst eluded the community. here   we present the measurement of the redshift of grb 970228, and, based on its spectroscopic and photometric properties, identify the host as an underluminous, but otherwise normal galaxy at redshift @xmath0 undergoing a modest level of star formation. at this redshift  , the grb released an isotropic equivalent energy of.   we find no evidence that the host is much bluer or forming stars more rigorously than the general field population.   in fact, by all accounts in our analysis ( color  magnitude, magnitude  radius, star - formation rate, balmer - break amplitude ) the host properties appear typical for faint blue field galaxies at comparable redshifts.   ( h
we use a @xmath0ks _ chandra _ observation to study ram - pressure stripping in ngc  4552 ( m89 ), an elliptical galaxy in the virgo cluster.   _ chandra _ images in the @xmath1kev band show a sharp leading edge in the surface brightness @xmath2kpc north of the galaxy center, a cool ( @xmath3kev ) tail with mean density @xmath4@xmath5 extending @xmath6kpc to the south of the galaxy, and two @xmath7kpc horns of emission extending southward away from the leading edge.   these are all features characteristic of supersonic ram - pressure stripping of galaxy gas, due to ngc  4552 s motion through the surrounding virgo icm.   fitting the surface brightness profile and spectra across the leading edge, we find the galaxy gas inside the edge is cooler ( @xmath8kev ) and denser ( @xmath9@xmath5 ) than the surrounding virgo icm ( @xmath10kev and @xmath11@xmath5 ).   the resulting pressure ratio between the free - streaming icm and cluster gas at the stagnation point is @xmath12 for galaxy gas metallicities of @xmath13, which suggests that ngc  4552 is moving supersonically through the cluster with a velocity @xmath14kms@xmath15(mach @xmath16 ) at an angle @xmath17 towards us with respect to the plane of the sky.
we report on an observing campaign in march 2001 to monitor the brightness of the later arriving q0957 + 561 b image in order to compare with the previously published brightness observations of the ( first arriving ) a image.   the 12 participating observatories provided 3543 image frames which we have analyzed for brightness fluctuations. from our classical methods for time delay determination, we find a @xmath0 day time delay which should be free of effects due to incomplete sampling. during the campaign period,   the quasar brightness was relatively constant and only small fluctuations were found ; we compare the structure function for the new data with structure function estimates for the 19956 epoch, and show that the structure function is statistically non - stationary.   we also examine the data for any evidence of correlated fluctuations at zero lag.   we discuss the limits to our ability to measure the cosmological time delay if the quasar s emitting surface is time resolved, as seems likely.
the solar system beyond neptune is believed to house a population of small primordial bodies left over from the planet formation process.   the region up to heliocentric distance @xmath0 ( the kuiper belt ) may be the source of the observed short period comets. in this region, the phase space structure near orbital resonances with neptune   is of special interest for the long term stability of orbits.   there is reason to believe that a significant fraction ( perhaps most ) of the kuiper belt objects reside preferentially in these resonance locations.   this paper describes the dynamics of small objects near the major orbital resonances with neptune.   estimates of the widths of stable resonance zones as well as the properties of resonant orbits are obtained from the circular, planar restricted three - body model.   although this model does not contain the full complexity of the long term orbital dynamics of kuiper belt objects subject to the full n - body perturbations of all the planets, it does provide a baseline for the phase space structure and properties of resonant orbits in the trans - neptunian solar system.   # 1o(#1 ) # 1 # 1to 0pt#1    to appear in the astronomical journal    submitted : june 1995 ; revised : august 1995
we describe here the first experimental realization of a heat interferometer, thermal counterpart of the well - known superconducting quantum interference device ( squid ).   these findings demonstrate, on the first place, the existence of phase - dependent heat transport in josephson - based superconducting circuits and, on the second place, open the way to novel ways of mastering heat at the nanoscale. combining the use of external magnetic fields for phase biasing and different josephson junction architectures we show here that a number of heat interference patterns can be obtained.   the experimental realization of these architectures, besides being relevant from a fundamental physics point of view, might find important technological application as building blocks of phase - coherent quantum thermal circuits. in particular, the performance of two different heat rectifying devices is analyzed.
we present a novel way of constructing reduced models for systems of ordinary differential equations. in particular  , the approach combines the concepts of renormalization and effective field theory developed in the context of high energy physics and the mori - zwanzig formalism of irreversible statistical mechanics.   the reduced models we construct depend on coefficients which measure the importance of the different terms appearing in the model and need to be estimated.   the proposed approach allows the estimation of these coefficients on the fly by enforcing the equality of integral quantities of the solution as computed from the original system and the reduced model. in this way we are able to construct stable reduced models of higher order than was previously possible   the method is applied to the problem of computing reduced models for ordinary differential equation systems resulting from fourier expansions of singular ( or near - singular ) time - dependent partial differential equations.   results for the 1d burgers and the 3d incompressible euler equations are used to illustrate the construction.   we also present, for the 1d burgers and the 3d euler equations, a simple and efficient recursive algorithm for calculating the higher order terms.
* abstract *    models of structure formation in the universe postulate that matter distributions observed today in galaxy catalogs arise, through a complex non - linear dynamics, by gravitational evolution from a very uniform initial state.   dark matter plays the central role of providing the primordial density seeds which will govern the dynamics of structure formation.   we critically examine the role of cosmological dark matter by considering three different and related issues : basic statistical properties of theoretical initial density fields, several elements of the gravitational many - body dynamics and key correlation features of the observed galaxy distributions are discussed, stressing some useful analogies with known systems in modern statistical physics.
' '' ''    aspects of the formation and equilibration of a quark - gluon plasma are explored using a quantum kinetic equation, which involves a non - markovian, abelian source term for quark and antiquark production and, for the collision term, a relaxation time approximation that defines a time - dependent quasi - equilibrium temperature and collective velocity.   the strong abelian field is determined via the simultaneous solution of maxwell s equation.   a particular feature of this approach is the appearance of plasma oscillations in all thermodynamic observables.   their presence can lead to a sharp increase in the time - integrated dilepton yield.
we have developed a concrete quantum simulation scheme and experimentally simulated a pairing model on an nmr quantum computer.   the design of our experiment includes choosing an appropriate initial state in order to make our scheme scalable in near future, and the accomplishment of our experiment makes use of twice fourier transforms so that our method is applicable to other physical models.   our results show that the experimental simulation can give the spectrum of the simulated hamiltonian.   consequently, the potential power of a quantum computer on the simulation of complex physical systems is verified.
in the present work we study the c8 flare occurred on september 26, 2000 at 19:49  ut and observed by the soho / sumer spectrometer from the beginning of the impulsive phase to well beyond the disappearance in the x - rays.   the emission first decayed progressively through equilibrium states until the plasma reached 2 - 3  mk.   then, a series of cooler lines, i.e.,,, and ( formed in the temperature range @xmath0 under equilibrium conditions ), are emitted at the same time and all evolve in a similar way. here   we show that the simultaneous emission of lines with such a different formation temperature is due to thermal instability occurring in the flaring plasma as soon as it has cooled below @xmath1 mk.   we can qualitatively reproduce the relative start time of the light curves of each line in the correct order with a simple ( and standard ) model of a single flaring loop.   the agreement with the observed light curves is greatly improved, and a slower evolution of the line emission is predicted, if we assume that the model loop consists of an ensemble of subloops or strands heated at slightly different times.   our analysis can be useful for flare observations with sdo / eve.
i briefly summarize the main tenets of unified schemes of bl lacs and low - luminosity radio galaxies, discussing in particular the evolution of this field after the como 1988 meeting.   i also examine some of the open problems and complications of the simplest scheme.   finally, the question of the existence of two classes of bl lacs and our related change of perspective in the past few years are also addressed.
search of life elsewhere in the galaxy is very fascinating area for planetary scientists and astrobiologists.   earth similarity index ( esi ) is defined as geometrical mean of four physical parameters ( such as radius, density, escape velocity and surface temperature ), which is ranging from 1 ( identical to earth ) to 0 ( dissimilar to earth ). in this work,   esi is re - defined as six parameters by introducing the two new physical parameters like revolution and surface gravity and is called as new earth similarity index ( nesi ).   the main focus of this paper is to search tardigrade water - life on exoplanets by varying the temperature parameter in nesi, which is called as tardigrade similarity index ( tsi ), which is ranging from 1 ( tardigrade can survive ) to 0 ( tardigrade can not survive ). here   the nesi and tsi is cataloged and analyzed for almost 3370 confirmed exoplanets.
a method to approximate transmission probabilities for a nonseparable multidimensional barrier is applied to a waveguide model.   the method uses complex barrier - crossing orbits to represent reaction probabilities in phase space and is uniform in the sense that it applies at and above a threshold energy at which classical reaction switches on. above this threshold the geometry of the classically reacting region of phase space is clearly reflected in the quantum representation.   two versions of the approximation are applied. a harmonic version which uses dynamics linearised around an instanton orbit is valid only near threshold but is easy to use  . a more accurate and more widely applicable version using nonlinear dynamics is also described.
we have used a relatively long, contiguous vhf observation of a bright cosmic radio source ( cygnus a ) with the very large array ( vla ) to demonstrate the capability of this instrument to study the ionosphere.   this interferometer, and others like it, can observe ionospheric total electron content ( tec ) fluctuations on a much wider range of scales than is possible with many other instruments.   we have shown that with a bright source, the vla can measure differential tec values between pairs of antennas ( @xmath0 ) with an precision of @xmath1 tecu. here  , we detail the data reduction and processing techniques used to achieve this level of precision. in addition  , we demonstrate techniques for exploiting these high - precision @xmath0 measurements to compute the tec gradient observed by the array as well as small - scale fluctuations within the tec gradient surface.   a companion paper details specialized spectral analysis techniques used to characterize the properties of wave - like fluctuations within this data.
plane - symmetric gravitational waves are considered as gravitational lenses.   numbers of images, frequency shifts, mutual angles, and image distortion parameters are computed exactly in essentially all non - singular plane wave spacetimes. for a fixed observation event in a particular plane wave spacetime  , the number of images is found to be the same for almost every source.   this number can be any positive integer, including infinity.   wavepackets of finite width are discussed in detail as well as waves which maintain a constant amplitude for all time.   short wavepackets are found to generically produce up to two images of each source which appear ( separately ) only some time after the wave has passed.   they are initially infinitely bright, infinitely blueshifted images of the infinitely distant past.   later, these images become dim and acquire a rapidly - increasing redshift. for sufficiently weak wavepackets,   one such `` flash '' almost always exists.   the appearance of a second flash requires that the ricci tensor inside the wave exceed a certain threshold.   this might occur if a gravitational plane wave is sourced by, e.g., a sufficiently strong electromagnetic plane wave.
a parity - time ( pt)-symmetric system with periodically varying - in - time gain and loss modeled by two coupled schrdinger equations ( dimer ) is studied.   it is shown that the problem can be reduced to a perturbed pendulum - like equation.   this is done by finding two constants of motion.   firstly, a generalized problem using melnikov type analysis and topological degree arguments is studied for showing the existence of periodic ( libration ), shift periodic ( rotation ), and chaotic solutions.   then these general results are applied to the pt - symmetric dimer.   it is interestingly shown that if a sufficient condition is satisfied, then rotation modes, which do not exist in the dimer with constant gain - loss, will persist.   an approximate threshold for pt - broken phase corresponding to the disappearance of bounded solutions is also presented.   numerical study is presented accompanying the analytical results.
results are presented for highly accurate _ ab initio _  variational calculation of the rotation - vibration energy levels of h@xmath0o@xmath0  in its electronic ground state.   these results use a recently computed potential energy surface and the variational nuclear - motion programmes warv4, which uses an exact kinetic energy ( eke ) operator, and trove, which uses a numerical expansion for the kinetic energy.   the trove calculations are performed for levels with high values of rotational excitation, @xmath1 up to 35.   the purely _ ab initio   _  calculations of the rovibrational energy levels reproduce the observed levels with a standard deviation of about 1 @xmath2, similar to that of the @xmath3 calculation as the discrepancy between theory and experiment for rotational energies within a given vibrational state is substantially determined by the error in the vibrational band origin.   minor adjustments are made to the _ ab initio _  equilibrium geometry and to the height of the torsional barrier.   using these and correcting the band origins using the error in @xmath3 states lowers the standard deviation of the observed @xmath4 calculated energies to only 0.002 @xmath2  for levels up to @xmath5 and 0.02   @xmath2 for all experimentally know energy levels, which extend up to @xmath6.    _   _    * *
decameter wavelength radio emission is finely structured in solar bursts. for their research   it is very important to use a sufficient sensitivity of antenna systems. in this paper   we study an influence of the radiotelescope - antenna effective area on the results of decameter solar radio observations. for this purpose   we compared the solar bursts received by the array of 720 ground - based dipoles and the single dipole of the radiotelescope utr-2.   it s shown that a larger effective area of the ground - based antenna allows us to measure a weaker solar emission and to distinguish a fine structure of strong solar events.   this feature has been also verified by simultaneous ground- and space - based observations in the overlapping frequency range.       sun : radio radiation  instrumentation : spectrographs  space vehicles : instruments
this paper defines the syntax and semantics of the input language of the asp grounder gringo.   the definition covers several constructs that were not discussed in earlier work on the semantics of that language, including intervals, pools, division of integers, aggregates with non - numeric values, and lparse - style aggregate expressions.   the definition is abstract in the sense that it disregards some details related to representing programs by strings of ascii characters.   it serves as a specification for gringo from version 4.5 on.    to appear in theory and practice of logic programming ( tplp ), proceedings of iclp 2015
we investigate the physical processes in which an electron, upon return to its parent ion, promotes a second electron to an excited state, from which it subsequently tunnels. employing the strong - field approximation and saddle - point methods  , we perform a detailed analysis of the dynamics of the two electrons, in terms of quantum orbits, and delimit constraints for their momentum components parallel to the laser - field polarization.   the kinetic energy of the first electron, upon return, exhibits a cutoff slightly lower than @xmath0, where @xmath1 is the ponderomotive energy, as in rescattered above - threshold ionization ( ati ).   the second electron leaves the excited state in a direct ati - like process, with the maximal energy of @xmath2.   we also compute electron - momentum distributions, whose maxima agree with our estimates and with other methods.
in this paper, we consider the generalized measurement where one particular quantum signal is unambiguously extracted from a set of non - commutative quantum signals and the other signals are filtered out.   simple expressions for the maximum detection probability and its povm are derived.   we applyl such unambiguous quantum state filtering to evaluation of the sensing of decoherence channels.   the bounds of the precision limit for a given quantum state of probes and possible device implementations are discussed.
 we present _ spitzer _ irac @xmath0 and mips @xmath1 point - source catalogs for seven galaxies : ngc@xmath2, m@xmath3, ngc@xmath4, ngc@xmath5, m@xmath6, ngc@xmath7, and ngc@xmath8.   the catalogs contain a total of @xmath9 sources and were created by dual - band selection of sources with @xmath10 detections at both @xmath11 and @xmath12.   the source lists become significantly incomplete near @xmath13.   we complement the @xmath11 and @xmath12 fluxes with @xmath14, @xmath15 and @xmath1 fluxes or @xmath16 upper limits using a combination of psf and aperture photometry.   this catalog is a resource as an archive for studying mid - infrared transients and for planning observations with the james webb space telescope.
we present a study of age - related spectral signatures observed in 25 young low - mass objects that we have previously determined as possible kinematic members of five young moving groups : the local association ( pleiades moving group, age=20 - 150 myr ), the ursa major group ( sirius supercluster, age=300 myr ), the hyades supercluster ( age=600 myr ), ic 2391 supercluster ( age=3555 myr ) and the castor moving group ( age=200 myr ). in this paper   we characterize the spectral properties of observed high or low resolution spectra of our kinematic members by fitting theoretical spectral distributions.   we study signatures of youth, such as lithium  i 6708 , h@xmath0 emission and other age - sensitive spectroscopic signatures in order to confirm the kinematic memberships through age constraints.   we find that 21 ( 84% ) targets show spectroscopic signatures of youth in agreement with the age ranges of the moving group to which membership is implied. for two further objects,   age - related constraints remain difficult to determine from our analysis.   in addition, we confirm two moving group kinematic candidates as brown dwarfs.       stars : low - mass, brown dwarfs  stars : kinematics
set of analytic solutions of the geodesic equation in a spherical conformal spacetime is presented.   solutions of this geodesics can be expressed in terms of the weierstrass @xmath0 function and the kleinian @xmath1 function.   using conserved energy and angular momentum we can characterize the different orbits. also, considering parametric diagrams and effective potentials, we plot some possible orbits.   moreover, with the help of analytical solutions, we investigate the light deflection for such an escape orbit.
we study the quantum mechanical consistency of noncommutative gauge theories by perturbatively analyzing the wilsonian quantum effective action in the matrix formulation. in the process of integrating out uv states  , we find new divergences having dual uv - ir interpretations and no analogues in ordinary quantum field theories.   the appearance of these new uv - ir divergences has profound consequences for the renormalizability of the theory.   in particular, renormalizability fails in any nonsupersymmetric noncommutative gauge theory.   in fact, we argue that renormalizability generally fails in any noncommutative theory that allows quantum corrections beyond one - loop.   thus, it seems that noncommutative quantum theories are extremely sensitive to the uv, and only the softest uv behavior can be tolerated.
iron - base superconductors exhibits features of systems where the fulde - ferrel - larkin - ovchinnikov ( fflo ) phase, a superconducting state with non - zero total momentum of cooper pairs, is actively sought.   experimental and theoretical evidence points strongly to the fflo phase in these materials above the pauli limit. in this article   we discuss the ground state of iron - base superconductors near the critical magnetic field and the full @xmath0 phase diagram for pnictides in case of intra - band pairing, in a three - band model with @xmath1 symmetry.
we report on the first simultaneous observation of an h@xmath0 moreton wave, the corresponding euv fast coronal waves, and a slow and bright euv wave ( typical eit wave ).   associated with an x6.9 flare that occurred on 2011 august 9 at the active region noaa 11263, we observed a moreton wave in the h@xmath0 images taken by the solar magnetic activity research telescope ( smart ) at hida observatory of kyoto university. in the euv images obtained by the atmospheric imaging assembly ( aia ) on board the _ solar dynamic observatory _ ( _ sdo _ ) we found not only the corresponding euv fast `` bright '' coronal wave, but also the euv fast `` faint '' wave that is not associated with the h@xmath0 moreton wave.   we also found a slow euv wave, which corresponds to a typical eit wave.   furthermore, we observed, for the first time, the oscillations of a prominence and a filament, simultaneously, both in the h@xmath0 and euv images. to trigger the oscillations by the flare - associated coronal disturbance  , we expect a coronal wave as fast as the fast - mode mhd wave with the velocity of about 570  800  km  s  @xmath1.   these velocities are consistent with those of the observed moreton wave and the euv fast coronal wave.
in this paper the effect of biaxial and uniaxial strain on the mobility of single - layer mos@xmath0 for temperatures t @xmath1 100 k is investigated. scattering from intrinsic phonon modes, remote phonon and charged impurities   are considered along with static screening.   ab - initio simulations are utilized to investigate the strain induced effects on the electronic bandstructure and the linearized boltzmann transport equation is used to evaluate the low - field mobility under various strain conditions.   the results indicate that the mobility increases with tensile biaxial and tensile uniaxial strain along the armchair direction. under compressive strain  , however, the mobility exhibits a non - monotonic behavior when the strain magnitude is varied.   in particular, with a relatively small compressive strain of 1% the mobility is reduced by about a factor of two compared to the unstrained condition, but with a larger compressive strain the mobility partly recovers such a degradation.
we show how the viscous evolution of keplerian accretion discs can be understood in terms of simple kinetic theory. although standard physics texts give a simple derivation of momentum transfer in a linear shear flow using kinetic theory, many authors, as detailed by hayashi & matsuda 2001, have had difficulties applying the same considerations to a circular shear flow.   we show here how this may be done, and note that the essential ingredients are to take proper account of, first, isotropy locally in the frame of the fluid and, second, the geometry of the mean flow.   9grs  1915 + 105     accretion discs -circumstellar matter - stars : accretion
probability distributions of money, income, and energy consumption per capita are studied for ensembles of economic agents.   the principle of entropy maximization for partitioning of a limited resource gives exponential distributions for the investigated variables.   a non - equilibrium difference of money temperatures between different systems generates net fluxes of money and population. to describe income distribution, a stochastic process with additive and multiplicative components is introduced.   the resultant distribution interpolates between exponential at the low end and power law at the high end, in agreement with the empirical data for usa.   we show that the increase of income inequality in usa originates primarily from the increase of the income fraction going to the upper tail, which now exceeds 20% of the total income. analyzing the data from the world resources institute, we find that the distribution of energy consumption per capita around the world can be approximately described by the exponential function.   comparing the data for 1990, 2000, and 2005, we discuss the effect of globalization on the inequality of energy consumption.
with the suzaku satellite, we observed an unidentified tev gamma - ray source hess j1741@xmath0302 and its surroundings.   no diffuse or point - like x - ray sources are detected from the bright southern emission peak of hess j1741@xmath0302. from its neighborhood, we found a new intermediate polar candidate at the position of @xmath1, which is designated as suzaku j174035.6@xmath0301416.   the spectrum of suzaku j174035.6@xmath0301416 exhibits emission lines at the energy of 6.4, 6.7 and 7.0 kev, which can be assigned as the k@xmath2 lines from neutral, he - like and h - like iron, respectively.   a coherent pulsation is found at a period of 432.1 @xmath3 0.1 s. the pulse profile is quasi - sinusoidal in the hard x - ray band ( 4@xmath08 kev ), but is more complicated in the soft x - ray band ( 1@xmath03 kev ).   the moderate period of pulsation, the energy flux, and the presence of the iron k@xmath2 lines indicate that suzaku j174035.6@xmath0301416 is likely an intermediate polar, a subclass of magnetized white dwarf binaries ( cataclysmic variables ). based on these discoveries,   we give some implications on the origin of gcdx and brief comments on hess j1741@xmath0302 and psr b1737@xmath030.
in this paper, we present a general method for trade off between performance and accuracy of distributed calculations by performing data sampling. sampling was a topic of extensive research that recently received a boost of interest.   we provide a sampling method targeted at separate, non - collaborating, vertically partitioned datasets. the method is exemplified and tested on approximation of intersection set both without and with privacy - preserving mechanism.   an analysis of the bound on error as a function of the sample size is discussed and heuristic algorithm is suggested to further improve the performance.   the algorithms were implemented and experimental results confirm the validity of the approach.
we investigate the evolution of the networks of the cosmic strings in angled brane inflation.   we show how they can be distinguished from the conventional ones.   the cosmic strings in angled inflation are the daughter @xmath0 branes that are extended between the mother @xmath1 branes. in the effective action  , the strings should have a moduli, since the endpoints of the @xmath0 branes can move freely on the @xmath1 branes.   then naturally the position of the @xmath0 branes, which corresponds to the moduli of the @xmath2-dimensional effective action, can vary along the cosmic strings.   the variation of the moduli results in the peculiar @xmath2-dimensional kink configurations.   the kinks are the monopoles on the strings.   therefore, the cosmic strings in angled inflation become necklaces.   the loops of the necklaces can shrink to produce stable winding states, which look like coils.   we show why the cosmological implications of the brane necklaces are important.   we point out that the cosmic strings in generic models of brane inflation should become necklaces, depending on the structure of the compactified space and the effective potential of the model.   sit - hep / tm-24    1.5 truecm   .75 truecm    * tomohiro matsuda *   .4 truecm    _ laboratory of physics, saitama institute of technology, _    _ fusaiji, okabe - machi, saitama 369 - 0293, japan   _    \1.   truecm addtoresetequationsection 1.
recently there has been considerable interest in the properties of carbon nanotori.   such nanotori can be parametrized according to their radii, their chiralities, and the twists that occur upon joining opposite ends of the nanotubes from which they are derived. in this paper, however, we demonstrate that many physically distinct nanotori with wildly different parameters nevertheless share identical band structures, energy spectra, and electrical conductivities.   this occurs as a result of certain geometric symmetries known as modular symmetries which are direct consequences of the properties of the compactified graphene sheet. using these symmetries  , we show that there is a dramatic reduction in the number of spectrally distinct carbon nanotori compared with the number of physically distinct carbon nanotori.   the existence of these modular symmetries also allows us to demonstrate that many statements in the literature concerning the electronic properties of nanotori are incomplete because they fail to respect the spectral equivalences that follow from these symmetries.   we also find that as a result of these modular symmetries, the fraction of spectrally distinct nanotori which are metallic is approximately three times greater than would naively be expected on the basis of standard results in the literature. finally, we demonstrate that these modular symmetries also extend to cases in which our carbon nanotori enclose non - zero magnetic fluxes.   .7ex  .7ex   = cmss10 = cmss10 at 7pt epsf
we report on microwave measurements on dyba@xmath0cu@xmath1o@xmath2 monodomains grown by the top - seeded melt - textured technique.   we measured the field increase of the surface resistance @xmath3 in the a - b plane at 48.3 ghz.   measurements were performed at fixed temperatures in the range 70 k - @xmath4 with a static magnetic field @xmath5 t parallel to the c - axis. low field steep increase of the dissipation, typical signature of the presence of weak links, is absent, thus indicating the single - domain behaviour of the sample under study.   the magnetic field dependence of @xmath3 is ascribed to the dissipation caused by vortex motion.   the analysis of @xmath6 points to a free - flow regime, thus allowing to obtain the vortex viscosity as a function of temperature.   we compare the results with those obtained on re - bco systems.   in particular, we consider strongly pinned films of yba@xmath0cu@xmath1o@xmath2 with nanometric bazro@xmath1 inclusions.   +    pacs : 74.25.nn, 74.72.-h, 74.81.bd, 74.25.op + keywords : surface impedance ; dybco ; monodomain ; vortex viscosity +     corresponding author : + dr.   nicola pompeo + postal address : dipartimento di fisica, universit roma tre, via della vasca navale 84 - 00146 rome, italy + phone : + 39 06 57337260 + fax : + 39 06 57337102 + e - mail address : pompeo@fis.uniroma3.it
the glauber dynamics of various models ( rem  like trap models, brownian motion, bm model, ising chain and sk model ) is analyzed in relation with the existence of ageing. from a finite size glauber matrix, we calculate a time @xmath0 after which the system has relaxed to the equilibrium state. the case of metastability is also discussed.   if the only non zero overlaps between pure states are only self  overlaps ( rem  like trap models, bm model ), the existence or absence of ageing depends only on the behavior of the density of eigenvalues for small eigenvalues.   we have carried out a detailed numerical and analytical analysis of the density of eigenvalues of the rem  like trap models. in this case, we show that the behavior of the density of eigenvalues for typical trap realizations is related to the spectral dimension of the equivalent random walk model  .    16.8cm-.4cm-1 cm    plus 0.2pt minus 0.1pt
the coordinate bethe ansatz solutions of the @xmath0 model for a one - dimensional spin-1/2 chain are analyzed with focus on the statistical properties of the constituent quasiparticles.   emphasis is given to the special cases known as @xmath1, @xmath2, and ising models, where considerable simplifications occur.   the @xmath0 spectrum can be generated from separate pseudovacua as configurations of sets of quasiparticles with different exclusion statistics.   these sets are complementary in the sense that the pseudovacuum of one set contains the maximum number of particles from the other set.   the bethe ansatz string solutions of the @xmath2 model evolve differently in the planar and axial regimes. in the ising limit they become ferromagnetic domains with integer - valued exclusion statistics. in the @xmath1 limit they brake apart into hard - core bosons with ( effectively ) fermionic statistics.   two sets of quasiparticles with spin 1/2 and fractional statistics are distinguished, where one set ( spinons ) generates the @xmath0 spectrum from the unique, critical ground state realized in the planar regime, and the other set ( solitons ) generates the same spectrum from the twofold, antiferromagnetically ordered ground state realized in the axial regime. in the ising limit,   the solitons become antiferromagnetic domain walls.   xxz model, bethe ansatz, string hypothesis, fractional statistics, spinons, solitons.
breaks in the radial luminosity profiles of galaxies have been until now mostly studied averaged over discs.   here we study separately breaks in thin and thick discs in 70 edge - on galaxies using imaging from the spitzer survey of stellar structure in galaxies.   we built luminosity profiles of the thin and the thick discs parallel to midplanes and we found that thin discs often truncate ( 77% ).   thick discs truncate less often ( 31% ), but when they do, their break radius is comparable with that in the thin disc.   this suggests either two different truncation mechanisms  one of dynamical origin affecting both discs simultaneously and another one only affecting the thin disc  or a single mechanism that creates a truncation in one disc or in both depending on some galaxy property.   thin discs apparently antitruncate in around 40% of galaxies. however, in many cases, these antitruncations are an artifact caused by the superposition of a thin disc and a thick disc with the latter having a longer scale length.   we estimate the real thin disc antitruncation fraction to be less than 15%.   we found that the ratio of the thick and thin stellar disc mass is roughly constant ( @xmath0 ) for circular velocities @xmath1, but becomes much larger at smaller velocities.   we hypothesize that this is due to a combination of a high efficiency of supernova feedback and a slower dynamical evolution in lower - mass galaxies causing stellar thin discs to be younger and less massive than in higher - mass galaxies.
we performed simulations of collapsars with different kerr parameters @xmath00, 0.5, 0.9, 0.95.   it is shown that a more rapidly rotating black hole is driving a more energetic jet.   no jet is seen for the case of schwartzschild black hole case, while the total energy of the jet is as large as @xmath1 erg for a rapidly rotating kerr black hole case ( @xmath2 ). in order to explain the high luminosity of a grb  , it is concluded that a rapidly rotating black hole is favored ( faster is better ).   we also find in the case of @xmath2 that ( i ) the stagnation region is clearly found in the jet region, ( ii ) the ordered poloidal field lines are seen in the jet, ( iii ) the jet region is surrounded by a wall - like structure that has a higher pressure than the jet region and contains strong vertical magnetic fields, and ( iv ) the jet is initiated by outgoing poynting flux from the outer horizon of the black hole ( blandford - znajek effect ).   the bulk lorentz factor of the jet is still of the order of unity.   however, energy density of electro - magnetic fields dominates the one of rest - mass in the jet.   it can be expected that a relativistic jet will be seen if we perform a simulation for a longer time scale ( of the order of @xmath3 sec ).
we present the results of a multiwavelength campaign searching for young objects in the intragroup medium of seven compact groups of galaxies : hcg 2, 7, 22, 23, 92, 100 and ngc 92.   we used fabry - perot velocity fields and rotation curves together with galex nuv and fuv images, optical r - band and hi maps to evaluate the stage of interaction of each group.   we conclude that groups ( i ) hcg 7 and hcg 23 are in an early stage of interaction, ( ii ) hcg 2 and hcg 22 are mildly interacting, and ( iii ) hcg 92, hcg 100 and ngc 92 are in a late stage of evolution.   evolved groups have a population of young objects in their intragroup medium while no such population is found within the less evolved groups.   we also report the discovery of a tidal dwarf galaxy candidate in the tail of ngc 92.   these three groups, besides containing galaxies which have peculiar velocity fields, also show extended hi tails.   our results indicate that the advanced stage of evolution of a group together with the presence of intragroup hi clouds may lead to star formation in the intragroup medium.
it is known that the maximum relative entropy ( mre ) method can be used to both update and approximate probability distributions functions in statistical inference problems. in this manuscript  , we apply the mre method to infer magnetic properties of ferromagnetic materials.   in addition to comparing our approach to more traditional methodologies based upon the ising model and mean field theory, we also test the effectiveness of the mre method on conventionally unexplored ferromagnetic materials with _
a relativistic light front treatment of nuclei is developed by performing light front quantization for a chiral lagrangian.   the energy momentum tensor and the appropriate hamiltonian are obtained.   three illustrations of the formalism are made.   ( 1 ) pion - nucleon scattering at tree level is shown to reproduce soft pion theorems.   ( 2 ) the one boson exchange treatment of nucleon - nucleon scattering is developed and shown ( by comparison with previous results of the equal time formulation ) to lead to a reasonable description of nucleon - nucleon phase shifts.   ( 3 ) the mean field approximation is applied to infinite nuclear matter, and the plus momentum distributions of that system are studied.   the mesons are found to carry a significant fraction of the plus momentum, but are inaccessible to experiments.
we present results on dijet and @xmath0+dijet production at hadron colliders obtained by supplementing the leading log bfkl resummation with energy and momentum conservation. for pure dijet production  , the inclusion of the bfkl radiation in the energy conservation leads to a decrease in the parton flux sufficient to counter - act the expected exponential increase in the cross section obtained for the partonic cross section.   other bfkl signatures such as the dijet azimuthal angle decorrelation do still survive.    * * forward jets and bfkl at hadron colliders * * +    jeppe r.  andersen +   +
we study the effectiveness of stationary - phase approximated post - newtonian waveforms currently used by ground - based gravitational - wave detectors to search for the coalescence of binary black holes by comparing them to an accurate waveform obtained from numerical simulation of an equal - mass non - spinning binary black hole inspiral, merger and ringdown.   we perform this study for the initial- and advanced - ligo detectors.   we find that overlaps between the templates and signal can be improved by integrating the match filter to higher frequencies than used currently.   we propose simple analytic frequency cutoffs for both initial and advanced ligo, which achieve nearly optimal matches, and can easily be extended to unequal - mass, spinning systems.   we also find that templates that include terms in the phase evolution up to 3.5 pn order are nearly always better, and rarely significantly worse, than 2.0 pn templates currently in use. for initial ligo   we recommend a strategy using templates that include a recently introduced pseudo-4.0 pn term in the low - mass ( @xmath0 ) region, and 3.5 pn templates allowing unphysical values of the symmetric reduced mass @xmath1 above this.   this strategy always achieves overlaps within 0.3% of the optimum, for the data used here. for advanced ligo   we recommend a strategy using 3.5 pn templates up to @xmath2, 2.0 pn templates up to @xmath3, pseudo-4.0 pn templates up to @xmath4, and 3.5 pn templates with unphysical @xmath1 for higher masses.   this strategy always achieves overlaps within 0.7% of the optimum for advanced ligo.
shear localization occurs in various instances of material instability in solid mechanics and is typically associated with hadamard - instability for an underlying model. while hadamard instability indicates the catastrophic growth of oscillations around a mean state,   it does not by itself explain the formation of coherent structures typically observed in localization.   the latter is a nonlinear effect and its analysis is the main objective of this article.   we consider a model that captures the main mechanisms observed in high strain - rate deformation of metals, and describes shear motions of temperature dependent non - newtonian fluids.   for a special dependence of the viscosity on the temperature, we carry out a linearized stability analysis around a base state of uniform shearing solutions, and quantitatively assess the effects of the various mechanisms affecting the problem : thermal softening, momentum diffusion and thermal diffusion.   then, we turn to the nonlinear model, and construct localized states - in the form of similarity solutions - that emerge as coherent structures in the localization process.   this justifies a scenario for localization that is proposed on the basis of asymptotic analysis in @xcite.
the motivation of this work is to illustrate the efficiency of some often overlooked alternatives to deal with optimization problems in systems and control. in particular  , we will consider a problem for which an iterative linear matrix inequality algorithm ( ilmi ) has been proposed recently.   as it often happens, this algorithm does not have guaranteed global convergence and therefore many methods may perform better.   we will put forward how some general purpose optimization solvers are more suited than the ilmi.   this is illustrated with the considered problem and example, but the general observations remain valid for many similar situations in the literature.   optimization ; linear systems ; positive filtering
we calculate the penetration depth @xmath0 in the @xmath1, @xmath2 and @xmath3 directions for a simple model of yba@xmath4cu@xmath5o@xmath6. in this model   there are two layers  representing a cuo@xmath4 plane and a cuo chain   per unit cell.   there is a bcs  like pairing ( both @xmath7 wave and @xmath8 wave are considered ) interaction localised in the cuo@xmath4 planes.   the cuo chains become superconducting at temperatures lower than @xmath9 because of their proximity to the planes, and there is an induced gap in the chains. since the temperature dependence of the penetration depth in the @xmath2 direction ( along the chains ) is sensitive to the size of the induced gap, the difference between the shapes of the penetration depth curves in the @xmath1 and @xmath2 directions reveals a great deal about the nature of the condensate in the chains.   we find that in our proximity model there are always regions of the chain fermi surface on which the induced gap is much smaller than @xmath9, so that the temperature dependence of @xmath10 is always different than that of @xmath11.   experimental observations of the of the @xmath12 anisotropy show nearly identical temperature dependences.   the main result of our paper, then, is that a simple proximity model in which the pairing interaction is localized to the planes, and the planes are coherently coupled to the chains can not account for the superfluid on the chains.
asymmetry is a common trait in spiral galaxies and is particularly frequent among magellanic spirals. to explore how morphological and kinematic asymmetry are affected by companion galaxies  , we analyze neutral hydrogen observations of the interacting magellanic spirals ngc 4618 and 4625.   the analysis of the h  i distribution revealed that about 10% of the total h  i mass of ngc 4618 resides in a looping tidal structure that appears to wrap all the way around the galaxy. through calculations based on derived h  i profiles,   we show that ngc 4618 and 4625 are no more asymmetric than non - interacting magellanic spirals analyzed by wilcots & prescott ( 2004 ).   we also derive rotation curves for the approaching and receding sides of each galaxy. by fitting the mean curves with an isothermal halo model, we calculate dynamical masses of @xmath0 m@xmath1 and @xmath2 m@xmath1 out to 6.7 kpc, for ngc 4618 and 4625 respectively.   while the rotation curves had systematically higher velocities on the receding side of each galaxy, the effect was no more pronounced than in studies of non - interacting spirals ( swaters et.   al. 1999 ).   the degree of interaction - driven asymmetry in both galaxies is indistinguishable from the intrinsic degree of asymmetry of lopsided galaxies.
we analyze photometric properties of 1384 cluster galaxies as a function of the normalized distance to cluster center.   these galaxies were selected in the central region ( @xmath0 0.8 ) of 14 southern abell clusters chosen from the southern abell cluster redshifts survey ( sars ). for 507 of these galaxies   we also obtained their luminosity profiles.   we have studied the morphology - clustercentric distance relation on the basis of the shape parameter @xmath1 of the srsic s law.   we also have analyzed the presence of a possible segregation in magnitude for both, the galaxy total luminosity and that of their components ( i.e. the bulge and the disk ).   results show a marginal ( @xmath2 level ) decrease of the total luminosity as a function of normalized radius.   however, when bulges are analyzed separately, a significant luminosity segregation is found ( @xmath3 and @xmath2 for galaxies in projection and member galaxies respectively ).   the fraction of bulges brighter than @xmath4 is three times larger in the core of clusters than in the outer region.   our analysis of the disk component suggests that disks are, on average, less luminous in the cluster core than at @xmath5.   in addition, we found that the magnitude - size relation as a function of @xmath6 indicates ( at @xmath2 level ) that disks are smaller and centrally brighter in the core of clusters.   however, the kormendy relation ( the bulge magnitude - size relation ) appears to be independent of environment.
we study structural properties of growing networks where both addition and deletion of nodes are possible.   our model network evolves via two independent processes. with rate @xmath0  , a node is added to the system and this node links to a randomly selected existing node. with rate @xmath1  , a randomly selected node is deleted, and its parent node inherits the links of its immediate descendants.   we show that the in - component size distribution decays algebraically, @xmath2, as @xmath3.   the exponent @xmath4 varies continuously with the addition rate @xmath0.   structural properties of the network including the height distribution, the diameter of the network, the average distance between two nodes, and the fraction of dangling nodes are also obtained analytically.   interestingly, the deletion process leads to a giant hub, a single node with a macroscopic degree whereas all other nodes have a microscopic degree.
we derive on the level of quantum optics expressions for the uncertainty of the photocount in a multi - mode multi - frequency setup.   the result depends on the quantum correlations of the individual modes and the frequency spectrum of the radiation, the latter leading to a frequency beating sometimes referred to as dynamic laser speckle.   when the mode structure of the radiation field is disturbed between source and detector, another contribution to the photocount uncertainty referred to as static speckle appears. to predict the size of this effect, we present a suitable definition of the etendue ( or phase space volume ) that links the number of modes of a radiation field to macroscopic quantities.
we examine the mechanism for generating a mass for a u(1 ) vector field introduced by stueckelberg.   first, it is shown that renormalization of the vector mass is identical to the renormalization of the vector field on account of gauge invariance.   we then consider how the vector mass affects the effective potential in scalar quantum electrodynamics at one - loop order.   the possibility of extending this mechanism to couple, in a gauge invariant way, a charged vector field to the photon is discussed.
we reexamine the glauber model and calculate the total reaction cross section as a function of energy in the low and intermediate energy range, where many of the corrections in the model, are effective.   the most significant effect in this energy range is by the modification of the trajectory due to the coulomb field.   the modification in the trajectory due to nuclear field is also taken into account in a self consistent way.   the energy ranges in which particular corrections are effective, are quantified and it is found that when the center of mass energy of the system becomes 30 times the coulomb barrier, none of the trajectory modification to the glauber model is really required.   the reaction cross sections for light and heavy systems, right from near coulomb barrier to intermediate energies have been calculated.   the exact nuclear densities and free nucleon - nucleon ( nn ) cross sections have been used in the calculations.   the center of mass correction which is important for light systems, has also been taken into account.   there is an excellent agreement between the calculations with the modified glauber model and the experimental data.   this suggests that the heavy ion reactions in this energy range can be explained by the glauber model in terms of free nn cross sections without incorporating any medium modification.    *   the glauber model and the heavy ion reaction cross section *    prashant shukla + _ nuclear physics division + bhabha atomic research center, mumbai 400 085, india _
the properties of scattering phases in quantum dots are analyzed with the help of lattice models.   we first derive the expressions relating the different scattering phases and the dot green functions.   we analyze in detail the friedel sum rule and discuss the deviation of the phase of the transmission amplitude from the friedel phase at the zeroes of the transmission.   the occurrence of such zeroes is related to the parity of the isolated dot levels.   a statistical analysis of the isolated dot wave - functions reveals the absence of significant correlations in the parity for large disorder and the appearance, for weak disorder, of certain dot states which are strongly coupled to the leads.   it is shown that large differences in the coupling to the leads give rise to an anomalous charging of the dot levels. a mechanism for   the phase lapse observed experimentally based on this property is discussed and illustrated with model calculations.   = 10000 epsf
we probe the dust extinction through the foreground disk of the overlapping galaxy pair ugc 5041 by analyzing b, i, and h band images.   the inclined foreground disk of this infrared - selected pair is almost opaque in b at a projected distance of @xmath0  kpc. from the images, we estimate directly the area - weighted distribution of differential near - ir extinction   : it is nearly gaussian with @xmath1 and @xmath2. for a homogenous dust distribution and a milky way extinction curve  , this corresponds to a face - on distribution p@xmath3 with a mean of @xmath4 and @xmath5. for a clumpy dust model the optical depth estimate increases to @xmath6 and @xmath7. even though the galaxy pair is subject to different selection biases and   our analysis is subject to different systematics, the result is consistent with existing case studies, indicating that @xmath8 is generic for late - type spirals near their half - light radii.   we outline how to estimate from p@xmath3 by how much background quasars are underreresented, where projected within @xmath9kpc of nearby spirals, such as damped ly-@xmath10 absorbers or gravitational lenses ; from our data we derive a factor of two deficit for flux - limited, optical surveys.   # 1    = cmsy10 scaled 1
using the mc herwiri1.031, we present the current status of the comparisons with lhc data of the predictions of our approach of exact amplitude - based resummation for precision qcd calculations.   qcd resummation ir - improved dglap - cs theory nlo - ps mc
in this paper we combine the wmap7 with lookback time and chandra gas fraction data to constrain the main cosmological parameters and the equation of state for the dark energy.   we find that the lookback time is a good measurement that can improve the determination of the equation of state for the dark energy with regard to other external data sets.   we conclude that larger lookback time data set will further improve our determination of the cosmological parameters.    _   keywords_:cosmological parameters, wmap measurements, lookback time, dark energy, monte carlo markov chains
hadrons inclusively produced with large @xmath0 in high - energy collisions originate from the jets, whose initial virtuality and energy are of the same order, what leads to an extremely intensive gluon radiation and dissipation of energy at the early stage of hadronization. besides, these jets have a peculiar structure : the main fraction of the jet energy is carried by a single leading hadron, so such jets are very rare.   the constraints imposed by energy conservation enforce an early color neutralization and a cease of gluon radiation.   the produced colorless dipole does not dissipate energy anymore and is evolving to form the hadron wave function.   the small and medium @xmath0 region is dominated by the hydrodynamic mechanisms of hadron production from the created hot medium.   the abrupt transition between the hydrodynamic and perturbative qcd mechanisms causes distinct minima in the @xmath0 dependence of the suppression factor @xmath1 and of the azimuthal asymmetry @xmath2.   combination of these mechanisms allows to describe the data through the full range of @xmath0 at different collision energies and centralities.
we present simulations of initially stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to radiatively driven implosion and star formation.   we use the smoothed particle hydrodynamics code seren ( ( *???   * hubber et al. 2010 ) ) and the healpix - based photoionization algorithm described in ( *???   * bisbas et al. ( 2009 ) ).   we find that the incident ionizing flux is the critical parameter determining the evolution : high fluxes simply disperse the cloud, whereas low fluxes trigger star formation.   we find a clear connection between the intensity of the incident flux and the parameters of star formation.
we present a simple treatment of the phenomenon of spontaneous parametric downconversion consisting of the coherent scattering of a single pump photon into an entangled photon pair inside a nonlinear crystal.   the energy and momentum entanglement of the quantum state of the generated twin photons are seen as a consequence of the fundamental indistinguishability of the time and the position in which the photon pair is created inside the crystal.   we also discuss some consequences of the photon entanglement.
we present a compilation of data on the 22 tentatively identified gamma - ray sources from the third egret catalog which may be detected by the next - generation imaging atmospheric cherenkov telescopes.   address = dept. of physics and astronomy, iowa state university, ames,   ia 50011, usa, email=petry@iastate.edu     address = laboratory for high energy astrophysics, nasa / gsfc, greenbelt, md 20771, usa, email=olr@egret.gsfc.nasa.gov
the mean square atomic displacement in hcp - phase solid @xmath0he has been measured in crystals with a molar volume of 21.3 @xmath1.   it is temperature independent from 1 k to 140 mk, with no evidence for an anomaly in the vicinity of the proposed supersolid transition.   the mean square displacement is different for in - plane motions ( 0.122 @xmath2 0.001 @xmath3 ) and out - of - plane motions ( 0.150 @xmath2 0.001 @xmath3 ).
we study the progenitor dependence of the black hole formation and its associated neutrino signals from the gravitational collapse of non - rotating massive stars, following the preceding study on the single progenitor model in @xcite.   we aim to clarify whether the dynamical evolution toward the black hole formation occurs in the same manner for different progenitors and to examine whether the characteristic of neutrino bursts is general having the short duration and the rapidly increasing average energies.   we perform the numerical simulations by general relativistic @xmath0-radiation hydrodynamics to follow the dynamical evolution from the collapse of pre - supernova models of 40m@xmath1 and 50m@xmath1 toward the black hole formation via contracting proto - neutron stars.   for the three progenitor models studied in this paper, we found that the black hole formation occurs in @xmath20.41.5 s after core bounce through the increase of proto - neutron star mass together with the short and energetic neutrino burst.   we found that density profile of progenitor is important to determine the accretion rate onto the proto - neutron star and, therefore, the duration of neutrino burst.   we compare the neutrino bursts of black hole forming events from different progenitors and discuss whether we can probe clearly the progenitor and/or the dense matter.
collisions of deformed uranium nuclei are studied in a monte - carlo glauber model. for u+u at zero impact parameter ( @xmath0 ) in the most favorable orientation ( tip - to - tip ), the transverse particle density ( charged - particle rapidity density per weighted transverse area of the initial participant zone ) increases by about 35% compared to au+au at @xmath0. to estimate the advantage of u+u over au+au in the context of real experiments at the relativistic heavy ion collider  , we examine the effect of a range of centrality cuts on the event sample. in terms of the transverse particle density,   the predicted advantage of u+u is about 16%.
we consider a minimally - coupled inflationary theory with a general scalar potential @xmath0 containing a stationary point of maximal order @xmath1. we show that asymptotically flat potentials can be associated to stationary points of infinite order and discuss the relation of our approach to the theory of @xmath2-attractors.
the yuan - tseh lee array for microwave background anisotropy ( amiba ) is the first interferometer dedicated to studying the cosmic microwave background ( cmb ) radiation at 3 mm wavelength.   the choice of 3@xmath0 mm was made to minimize the contributions from foreground synchrotron radiation and galactic dust emission.   the initial configuration of seven 0.6@xmath0 m telescopes mounted on a 6-m hexapod platform was dedicated in october 2006 on mauna loa, hawaii.   scientific operations began with the detection of a number of clusters of galaxies via the thermal sunyaev - zeldovich effect.   we compare our data with subaru weak lensing data in order to study the structure of dark matter.   we also compare our data with x - ray data in order to derive the hubble constant.
while network coding can be an efficient means of information dissemination in networks, it is highly susceptible to `` pollution attacks, '' as the injection of even a single erroneous packet has the potential to corrupt each and every packet received by a given destination. even when suitable error - control coding is applied, an adversary can, in many interesting practical situations, overwhelm the error - correcting capability of the code. to limit the power of potential adversaries,   a broadcast transformation is introduced, in which nodes are limited to just a single ( broadcast ) transmission per generation. under this broadcast transformation,   the multicast capacity of a network is changed ( in general reduced ) from the number of edge - disjoint paths between source and sink to the number of internally - disjoint paths.   exploiting this fact, a family of networks is proposed whose capacity is largely unaffected by a broadcast transformation.   this results in a significant achievable transmission rate for such networks, even in the presence of adversaries.   adversarial nodes, broadcast transformation, error correction, jlc networks, multicast capacity, network coding.
silicene is a monolayer of silicon atoms forming a two - dimensional honeycomb lattice.   we investigate the topological properties of a silicene superstructure generated by an external periodic potential.   the superstructure is a quantum spin - hall ( qsh ) insulator if it is topologically connected to silicene.   it is remarkable that two inequivalent k and k points in the silicene brillouin zone are identified in certain superstructures.   in such a case two dirac cones coexist at the same dirac point in the momentum space and they are hexagonally warped by the coulomb interaction.   we carry out a numerical analysis by taking an instance of the ( @xmath0 ) superstructure on the ( @xmath1 ) structure of the ag substrate.   we show that it is a qsh insulator, that there exists no topological phase transition by external electric field, and that the hexagonally warping occurs in the band structure.
in developing theories of nuclear binding energy such as density - functional theory, the effort required to make a fit can be daunting due to the large number of parameters that may be in the theory and the large number of nuclei in the mass table. for theories based on the skyrme interaction,   the effort can be reduced considerably by using the singular value decomposition to reduce the size of the parameter space.   we find that the sensitive parameters define a space of dimension four or so, and within this space a linear refit is adequate for a number of skyrme parameters sets from the literature.   we do not find marked differences in the quality of the fit between the sly4, the bsk4 and skp parameter sets.   the r.m.s.   residual error in even - even nuclei is about 1.5 mev, half the value of the liquid drop model.   we also discuss an alternative norm for evaluating mass fits, the chebyshev norm.   it focuses attention on the cases with the largest discrepancies between theory and experiment.   we show how it works with the liquid drop model and make some applications to models based on skyrme energy functionals.   the chebyshev norm seems to be more sensitive to new experimental data than the root - mean - square norm.   the method also has the advantage that candidate improvements to the theories can be assessed with computations on smaller sets of nuclei.   +    = 10000
the local structure and chemical bonding in two - phase amorphous cr@xmath0c@xmath1 nanocomposite thin films are investigated by cr @xmath2-edge ( @xmath3 ) x - ray absorption near - edge structure ( xanes ) and extended x - ray absorption fine structure ( exafs ) spectroscopies in comparison to theory. by utilizing the computationally efficient _ stochastic quenching _   ( sq ) technique, we reveal the complexity of different cr - sites in the transition metal carbides, highlighting the need for large scale averaging to obtain theoretical xanes and exafs spectra for comparison with measurements. as shown in this work, it is advantageous to use _ ab initio _ theory as an assessment to correctly model and fit experimental spectra and investigate the trends of bond lengths and coordination numbers in complex amorphous materials. with sufficient total carbon content ( @xmath4 30 at% ),   we find that the short - range coordination in the amorphous carbide phase exhibit similarities to that of a cr@xmath5c@xmath6 structure, while excessive carbons assemble in the amorphous carbon phase.
about 500d after explosion the light curve of the type ia sn  1998bu suddenly flattened and at the same time the spectrum changed from the typical nebular emission to a blue continuum with broad absorption and emission features reminiscent of the sn spectrum at early phases. we show that in analogy to sn  1991 t @xcite, this can be explained by the emergence of a light echo from a foreground dust cloud.   based on a simple model we argue that the amount of dust required can consistently explain the extinction which has been estimated by completely independent methods. because of the similar echo luminosity but much higher optical depth of the dust in sn  1998bu compared with sn  1991 t, we expect that the echo ring size of sn  1998bu grows faster than in sn  1991 t.   hst observations have indeed confirmed this prediction.
i report the discovery of two new galactic wolf - rayet stars in circinus via detection of their c, n and he near - infrared emission lines, using eso - ntt - sofi archival data. the h- and k - band spectra of wr67a and wr67b,   indicate that they are wolf - rayet stars of wn6h and wc8 sub - types, respectively.   wr67a presents a weak - lined spectrum probably reminiscent of young hydrogen rich main - sequence stars such as wr25 in car ob1 and hd97950 in ngc3603.   indeed, this conclusion is reinforced by the close morphological match of the wr67a h- and k - band spectra with that for wr21a, a known extremely massive binary system.   wr67b is probably a non - dusty wc8 wolf - rayet star that has a estimated heliocentric distance of 2.7@xmath00.9 kpc, which for its galactic coordinates, puts the star probably in the near portion of the scutum - centaurus arm.       stars : wolf - rayet ; infrared : stars
we introduce a new technique for constructing three - dimensional ( 3d ) models of incompressible riemann s - type ellipsoids and compressible triaxial configurations that share the same velocity field as that of riemann s - type ellipsoids.   our incompressible models are exact steady - state configurations ; our compressible models represent approximate steady - state equilibrium configurations.   models built from this method can be used to study a variety of relevant astrophysical and geophysical problems.
it has been a puzzle whether quarks may exist in the interior of massive neutron stars, since the hadron - quark phase transition softens the equation of state ( eos ) and reduce the neutron star ( ns ) maximum mass very significantly. in this work,   we consider the light u - boson that increases the ns maximum mass appreciably through its weak coupling to fermions.   the inclusion of the u - boson may thus allow the existence of the quark degrees of freedom in the interior of large mass neutron stars. unlike the consequence of the u - boson in hadronic matter, the stiffening role of the u - boson in the hybrid eos is not sensitive to the choice of the hadron phase models.   in addition, we have also investigated the effect of the effective qcd correction on the hybrid eos.   this correction may reduce the coupling strength of the u - boson that is needed to satisfy ns maximum mass constraint. while the inclusion of the u - boson also increases the ns radius significantly  , we find that appropriate in - medium effects of the u - boson may reduce the ns radii significantly, satisfying both the ns radius and mass constraints well.        20.6pt
we study, using both theory and molecular dynamics simulations, the relaxation dynamics of a microcanonical two dimensional self - gravitating system. after a sufficiently large time  , a gravitational cluster of @xmath0 particles relaxes to the maxwell - boltzmann distribution. the time to reach the thermodynamic equilibrium, however, scales with the number of particles. in the thermodynamic limit, @xmath1 at fixed total mass,   equilibrium state is never reached and the system becomes trapped in a non - ergodic stationary state.   an analytical theory is presented which allows us to quantitatively described this final stationary state, without any adjustable parameters.
we consider the ionisation of atomic hydrogen by a strong infrared field.   we extend and study in more depth an existing semi - analytical model. starting from the time - dependent schrdinger equation in momentum space and in the velocity gauge we substitute the kernel of the non - local coulomb potential by a sum of @xmath0 separable potentials, each of them supporting one hydrogen bound state.   this leads to a set of @xmath0 coupled one - dimensional linear volterra integral equations to solve.   we analyze the gauge problem for the model, the different ways of generating the separable potentials and establish a clear link with the strong field approximation which turns out to be a limiting case of the present model.   we calculate electron energy spectra as well as the time evolution of electron wave packets in momentum space.   we compare and discuss the results obtained with the model and with the strong field approximation and examine in this context, the role of excited states.
we reinvestigate the generation and accumulation of magnetic flux in optically thin accretion flows around active gravitating objects.   the source of the magnetic field is the azimuthal electric current associated with the poynting - robertson drag on the electrons of the accreting plasma.   this current generates magnetic field loops which open up because of the differential rotation of the flow.   we show through simple numerical simulations that what regulates the generation and accumulation of magnetic flux near the center is the value of the plasma conductivity. although the conductivity is usually considered to be effectively infinite for the fully ionized plasmas expected near the inner edge of accretion disks, the turbulence of those plasmas may actually render them much less conducting due to the presence of anomalous resistivity. we have discovered that if the resistivity is sufficiently high throughout the turbulent disk while it is suppressed interior to its inner edge, an interesting steady - state process is established : accretion carries and accumulates magnetic flux _ of one polarity _ inside the inner edge of the disk, whereas magnetic diffusion releases magnetic flux _ of the opposite polarity _ to large distances. in this scenario, magnetic flux of one polarity   grows and accumulates at a steady rate in the region inside the inner edge and up to the point of equipartition when it becomes dynamically important.   we argue that this inward growth and outward expulsion of oppositely - directed magnetic fields that we propose may account for the @xmath0  min cyclic variability observed in the galactic microquasar grs1915 + 105.
the rich galaxy cluster abell2204 exhibits edges in its x - ray surface brightness at @xmath0 and @xmath1 west and east of its center, respectively.   the presence of these edges, which were interpreted as sloshing cold fronts, implies that the intracluster medium was recently disturbed.   we analyze the properties of the intracluster medium using multiple _   _ observations of abell2204.   we find a density ratio @xmath2 and a temperature ratio @xmath3 ( projected, or @xmath4 deprojected ) across the western edge, and correspondingly @xmath5 and @xmath6 ( projected, or @xmath7 deprojected ) across the eastern edge.   these values are typical of cold fronts in galaxy clusters.   this, together with the spiral pattern observed in the cluster core, supports the sloshing scenario for abell2204.   no kelvin - helmholtz eddies are observed along the cold front surfaces, indicating that they are effectively suppressed by some physical mechanism.   we argue that the suppression is likely facilitated by the magnetic fields amplified in the sloshing motion, and deduce from the measured gas properties that the magnetic field strength should be greater than @xmath8 @xmath9 g and @xmath10 @xmath9 g along the west and east cold fronts, respectively.
the equation of state for radiation is derived in a canonical formulation of the electromagnetic field.   this allows one to include correction terms expected from canonical quantum gravity and to infer implications to the universe evolution in radiation dominated epochs.   corrections implied by quantum geometry can be interpreted in physically appealing ways, relating to the conformal invariance of the classical equations.
we conducted radio observations searching for oh 18-cm maser emission from a sample of 169 unclassified mipsgal compact galactic bubbles.   these sources are thought to be the circumstellar envelopes of different kinds of evolved stars.   our observations were aimed at shedding light on the nature of mipsgal bubbles, since their characterisation is a fundamental aid for the development of accurate physical models of stellar and galaxy evolution.   the maser emission is observatively linked to the last stages of the life of low- and intermediate - mass stars, which may constitute a significant fraction of the mipsgal bubbles. in particular oh masers are usually observed towards post - agb stars.   our observations were performed with the green bank telescope and, for each source, produced spectra around the four oh 18-cm transitions.   the observations were compared with archive interferometer data in order to exclude possible contamination from nearby sources.   the main result is that the oh maser emission is not a common feature among the mipsgal bubbles, with only one certain detection.   we conclude that among the mipsgal bubbles the post - agb stars could be very rare.       techniques : spectroscopic  masers  ism : lines and bands  stars : agb and post - agb
we have obtained high spatial resolution temperature and abundance profiles for the galaxy cluster abell 2029 with the _ chandra _ acis - s instrument.   our observations reveal that the spectra are well - fit by a single - phase gas in each annulus. while the temperature of the intracluster medium drops from @xmath0  kev at 3 ( 260  @xmath1  kpc ) to @xmath2  kev in the central @xmath3 ( 5  @xmath1  kpc ) of the cluster, there is no evidence for gas emitting at temperatures below 3  kev.   the addition of a cooling flow component does not improve the fits, despite previous claims for a massive cooling flow.   there is also no evidence for excess absorption above the galactic n@xmath4 value.   we also observe a steep fe abundance gradient, such that @xmath5  @xmath6(assuming meteoritic solar fe abundance ) in the core, consistent with significant enrichment from fe - rich type ia supernovae in the cd galaxy.   the fe abundance drops to @xmath7  @xmath6 at 3 ( 260  @xmath1  kpc ), in good agreement with previous _   _ measurements.   the high resolution image reveals neither a strong central point source, nor any filamentary structure related to a cooling flow or a merger.   the absence of a strong merger signature argues against the creation of the wide - angle - tail radio source morphology in a merger event.
we present a nonequilibrium strong - coupling approach to inhomogeneous systems of ultracold atoms in optical lattices.   we demonstrate its application to the mott - insulating phase of a two - dimensional fermi - hubbard model in the presence of a trap potential.   since the theory is formulated self - consistently, the numerical implementation relies on a massively parallel evaluation of the self - energy and the green s function at each lattice site, employing thousands of cpus. while the computation of the self - energy is straightforward to parallelize, the evaluation of the green s function requires the inversion of a large sparse @xmath0 matrix, with @xmath1. as a crucial ingredient,   our solution heavily relies on the smallness of the hopping as compared to the interaction strength and yields a widely scalable realization of a rapidly converging iterative algorithm which evaluates all elements of the green s function.   results are validated by comparing with the homogeneous case via the local - density approximation.   these calculations also show that the local - density approximation is valid in non - equilibrium setups without mass transport.
we present a complete prescription for the numerical calculation of surface green s functions and self - energies of semi - infinite quasi - onedimensional systems.   our work extends the results of sanvito _ et al. _    generating a robust algorithm to be used in conjunction with _ ab initio _ electronic structure methods.   we perform a detailed error analysis of the scheme and find that the highest accuracy is found if no inversion of the usually ill conditioned hopping matrix is involved. even in this case however a transformation of the hopping matrix that decreases its condition number is needed in order to limit the size of the imaginary part of the wave - vectors.   this is done in two different ways, either by applying a singular value decomposition and setting a lowest bound for the smallest singular value, or by adding a random matrix of small amplitude. by using the first scheme the size of the hamiltonian matrix is reduced, making the computation considerably faster for large systems. for most energies   the method gives high accuracy, however in the presence of surface states the error diverges due to the singularity in the self - energy.   a surface state is found at a particular energy if the set of solution eigenvectors of the infinite system is linearly dependent.   this is then used as a criterion to detect surface states, and the error is limited by adding a small imaginary part to the energy.
state - of - the - art techniques for 6d object pose recovery depend on occlusion - free point clouds to accurately register objects in 3d space. to deal with this shortcoming  , we introduce a novel architecture called _ iterative hough forest with histogram of control points _ that is capable of estimating the 6d pose of occluded and cluttered objects given a candidate 2d bounding box.   our _ iterative hough forest ( ihf ) _ is learnt using parts extracted only from the positive samples.   these parts are represented with _   histogram of control points ( hocp ) _, a `` scale - variant '' implicit volumetric description, which we derive from recently introduced implicit b - splines ( ibs ). the rich discriminative information provided by the scale - variant hocp features is leveraged during inference.   an automatic variable size part extraction framework iteratively refines the object s initial pose that is roughly aligned due to the extraction of coarsest parts, the ones occupying the largest area in image pixels.   the iterative refinement is accomplished based on finer ( smaller ) parts that are represented with more discriminative control point descriptors by using our _ iterative hough forest_. experiments conducted on a publicly available dataset report that our approach show better registration performance than the state - of - the - art methods.   +    object registration, 6 dof pose estimation, scale - variant hocp features, one class training, random forest, iterative refinement.
analytical investigations are made on bml two - dimensional traffic flow model with alternative movement and exclude - volume effect.   several exact results are obtained, including the upper critical density above which there are only jamming configurations asymptotically, and the lower critical density below which there are only moving configurations asymptotically.   the jamming transition observed in the ensemble average velocity takes place at another critical density @xmath0, which is dependent on the lattice size @xmath1 and is in the intermediate region between the lower and upper critical densities.   it is suggested that @xmath0 is proportional to a power of @xmath1, in good agreement with the numerical simulation.   the order parameter of this jamming transition is identified.    2
we present a ccd investigation of the poorly known smc young globular cluster ngc 458.   the ntt data, presented here, allowed us to study in detail the more internal regions of the cluster which are less contaminated by the field.   on the basis of theoretical isochrones, a preliminary evaluation of the age is also given.   latexlatex    psfig.sty -0.5pc -0.5pc -2pc
we investigate the effect of dark energy on the limits on the shear anisotropy in spatially homogeneous bianchi cosmological models obtained from measurements of the temperature anisotropies in the cosmic microwave background.   we shall primarily assume that the dark energy is modelled by a cosmological constant.   in general, we find that there are tighter bounds on the shear than in models with no cosmological constant, although the limits are ( bianchi ) model dependent.   in addition, there are special spatially homogeneous cosmological models whose rate of expansion is highly anisotropic, but whose cosmic microwave background temperature is measured to be exactly isotropic at one instant of time.   department of mathematics and statistics, dalhousie university, halifax, nova scotia, canada, b3h  3j5
debris disks are thought to be sculptured by neighboring planets.   the same is true for the edgeworth - kuiper debris disk, yet no direct observational evidence for signatures of giant planets in the kuiper belt dust distribution has been found so far.   here we model the dust distribution in the outer solar system to reproduce the dust impact rates onto the dust detector onboard the new horizons spacecraft measured so far and to predict the rates during the neptune orbit traverse. to this end, we take a realistic distribution of transneptunian objects to launch a sufficient number of dust grains of different sizes and follow their orbits by including radiation pressure, poynting - robertson and stellar wind drag, as well as the perturbations of four giant planets. in a subsequent statistical analysis, we calculate number densities and lifetimes of the dust grains in order to simulate a collisional cascade.   in contrast to the previous work, our model not only considers collisional elimination of particles, but also includes production of finer debris.   we find that particles captured in the @xmath0:@xmath1 resonance with neptune build clumps that are not removed by collisions, because the depleting effect of collisions is counteracted by production of smaller fragments.   our model successfully reproduces the dust impact rates measured by new horizons out to @xmath2 and predicts an increase of the impact rate of about a factor of two or three around the neptune orbit crossing.   this result is robust with respect to the variation of the vaguely known number of dust - producing scattered disk objects, collisional outcomes, and the dust properties.
the inherently high computational cost of iterative self - consistent - field ( scf ) methods proves to be a critical issue delaying visual and haptic feedback in real - time quantum chemistry. in this work,   we introduce two schemes for scf acceleration.   they provide a guess for the initial density matrix of the scf procedure generated by extrapolation techniques.   scf optimizations then converge in fewer iterations, which decreases the execution time of the scf optimization procedure.   to benchmark the proposed propagation schemes, we developed a test bed for performing quantum chemical calculations on sequences of molecular structures mimicking real - time quantum chemical explorations.   explorations of a set of six model reactions employing the semi - empirical methods pm6 and dftb3 in this testing environment showed that the proposed propagation schemes achieved speedups of up to thirty percent as a consequence of a reduced number of scf iterations.
we investigate the ground state phase diagram of the s=1/2 two - leg @xmath0 spin ladder system with an isotropic interchain coupling. in this model  , there is the berezinskii - kosterlitz - thouless transition which occurs at the @xmath1-haldane and the @xmath1-rung singlet phase boundaries.   it was difficult to determine the transition line using traditional methods.   we overcome this difficulty using the level spectroscopy method combined with the twisted boundary condition method, and we check the consistency. we find out that the phase boundary between @xmath1 phase and haldane phase lies on the @xmath2 line. and we show that there exist two different @xmath1 phases, which we can distinguish investigating a @xmath3 correlation function.
we show that it is possible to transfer two - bit information via encoding a single qubit in a conventional nuclear magnetic resonance ( nmr ) experiment with two very weakly polarized nuclear spins.   nevertheless, the experiment can not be regarded as a demonstration of superdense coding by means of nmr because it is based on the large number of molecules being involved in the ensemble state rather than the entanglement of the nmr states. following the discussions, an entanglement witness,   particularly applicable for nmr, is introduced based on separate and simultaneous measurement of the individual nuclear spin magnetizations.
we present and implement a probabilistic ( bayesian ) method for producing catalogs from images of stellar fields.   the method is capable of inferring the number of sources @xmath0 in the image and can also handle the challenges introduced by noise, overlapping sources, and an unknown point spread function ( psf ).   the luminosity function of the stars can also be inferred even when the precise luminosity of each star is uncertain, via the use of a hierarchical bayesian model.   the computational feasibility of the method is demonstrated on two simulated images with different numbers of stars.   we find that our method successfully recovers the input parameter values along with principled uncertainties even when the field is crowded.   we also compare our results with those obtained from the sextractor  software.   while the two approaches largely agree about the fluxes of the bright stars, the bayesian approach provides more accurate inferences about the faint stars and the number of stars, particularly in the crowded case.
the electron states in the field of a charged impurity in graphene in a magnetic field are studied numerically.   it is shown that a charged impurity removes the degeneracy of landau levels converting them into bandlike structures.   as the charge of impurity grows, the repulsion of sublevels of different landau levels with the same value of orbital momentum takes place leading to the redistribution of the wave function profiles of these sublevels near the impurity. by studying the polarization effects,   it is shown in agreement with the recent experiments that the effective charge of impurity can be very effectively tuned by chemical potential.   if the chemical potential is situated inside a landau level, then the charge of impurity is strongly diminished.   in addition, the polarization function in this case has a peak at zero momentum, which leads to the sign - changing oscillations of the screened potential as a function of distance.   if the chemical potential lies between the landau levels, then the screened potential does not change sign, the screening is minimal, and the charged impurity can strongly affect the electron spectrum.
any cutting - edge scientific research project requires a myriad of computational tools for data generation, management, analysis and visualization.   python is a flexible and extensible scientific programming platform that offered the perfect solution in our recent comparative genomics investigation @xcite. in this paper  , we discuss the challenges of this project, and how the combined power of biopython @xcite, matplotlib @xcite and swig @xcite were utilized for the required computational tasks.   we finish by discussing how python goes beyond being a convenient programming language, and promotes good scientific practice by enabling clean code, integration with professional programming techniques such as unit testing, and strong data provenance.
the serpens south embedded cluster, which is located at the constricted part in a long filamentary infrared dark cloud, is believed to be in very early stage of cluster formation.   we present results of near - infrared ( _ jhk_s ) polarization observations toward the filamentary cloud.   our polarization measurements of near - infrared point sources indicate a well - ordered global magnetic field that is perpendicular to the main filament, implying that the magnetic field is likely to have controlled the formation of the main filament. on the other hand, the sub - filaments, which converge on the central part of the cluster, tend to run along the magnetic field.   the global magnetic field appears to be curved in the southern part of the main filament.   such morphology is consistent with the idea that the global magnetic field is distorted by gravitational contraction along the main filament toward the northern part that contains largermass.   applying the chandrasekhar - fermi method, the magnetic field strength is roughly estimated to be a few @xmath0100 @xmath1 g, suggesting that the filamentary cloud is close to magnetically critical as a whole.
ordering of the heisenberg spin glass with the nearest - neighbor gaussian coupling is investigated by equilibrium monte carlo simulations in four and five dimensions.   ordering of the mean - field heisenberg spin glass is also studied for comparison.   particular attention is paid to the nature of the spin - glass and chiral - glass orderings.   our numerical data suggest that, in five dimensions, the model exhibits a single spin - glass transition at a finite temperature, where the spin - glass order accompanying the simultaneous chiral - glass order sets in. in four dimensions  , the model exhibits a marginal behavior.   chiral - glass transition at a finite temperature not accompanying the standard spin - glass order is likely to occur, while the critical region associated with the chiral - glass transition is very narrow suggesting that the dimension four is close to the marginal dimensionality.
we theoretically study in detail the hydrodynamic coupling of two equal - sized colloidal spheres at low reynolds numbers assuming the particles to be harmonically trapped with respect to both their positions and orientations. by taking into account the rotational motion  , we obtain a rich spectrum of collective eigenmodes whose properties we determine on the basis of pure symmetry arguments. extending recent investigations on translational correlations [ j.- c.   meiners and s.  r.  quake, phys.   rev.   lett.  * 82 *, 2211 ( 1999 ) ], we derive the complete set of auto- and cross - correlation functions emphasizing the coupling of rotation to translation which we illustrate in a few examples.   an important feature of our system is the self - coupling of translation and rotation of one particle mediated by the neighboring particle that is clearly visible in the appropriate auto - correlation function.   this coupling is a higher - order effect and therefore not included in the widely used rotne - prager approximation for the hydrodynamic mobilities.
we present a re - analysis of our @xmath0- and @xmath1-band photometry and light - curves for gcirs  16sw, a regular periodic source near the galactic center.   these data include those presented by @xcite ; we correct a sign error in their reduction, finding gcirs  16sw to be an eclipsing binary with no color variations.   we find the system to be an equal mass overcontact binary ( both stars overfilling their roche lobes ) in a circular orbit with a period @xmath2  days, an inclination angle @xmath3.   this confirms and strengthens the findings of @xcite that gcirs  16sw is an eclipsing binary composed of two @xmath4 stars, further supporting evidence of recent star formation very close to the galactic center.   finally, the calculated luminosity of each component is close to the eddington luminosity, implying that the temperature of 24400  k given by @xcite might be overestimated for these evolved stars.
in this work, we propose a new design of an ion trap which can enable us to generate state specific berry phase in a single trapped ion.   such a design will enable us to study the physics at the boundary of abelian and non - abelian symmetries and can also have significant impact in quantum computation.
high frequency  measurements of the magneto - impedance ( mi ) of glass - covered co@xmath0fe@xmath1b@xmath2si@xmath3 microwires are carried out with various metal - to - wire diameter ratios. a twin - peak  , anhysteretic behaviour is observed as a function of magnetic field.   a maximum in @xmath4 appears at different values of the frequency @xmath5, 125, 140 and 85 mhz with the corresponding diameter ratio @xmath6 = 0.80, 0.55 and 0.32.   we describe the measurement technique and interpret our results with a thermodynamic model that leads to a clearer view of the effects of @xmath6 on the maximum value of mi and the anisotropy field.
we investigate the effects of ram pressure on the ordered magnetic field of a galaxy hosting a radio halo and strong nuclear outflows.   new radio images in total and polarized intensity of the edge - on virgo galaxy ngc4388 were obtained within the chang - es evla project.   the unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field.   the nuclear outflow extends far into the halo to about 5kpc from the center and is spatially correlated with the @xmath0 and x - ray emission. for the first time, the southern outflow is detected. above and below both spiral arms   we find extended blobs of polarized emission with an ordered field oriented perpendicular to the disk.   the synchrotron lifetime of the cosmic ray electrons ( cres ) in these regions yields a mean outflow velocity of @xmath1, in agreement with a galactic wind scenario.   the observed symmetry of the polarized halo features in ngc 4388 excludes a compression of the halo gas by the ram pressure of the intra - cluster medium ( icm ).   the assumption of equilibrium between the halo pressure and the icm ram pressure yields an estimate of the icm density that is consistent with both the icm density derived from x - ray observations and the recent _ planck _ sunyaev - zeldovich measurements.   the detection of a faint radio halo around cluster galaxies could thus be used for an estimate of icm ram pressure.
we theoretically study hawking radiation processes from an analog acoustic black hole in a flowing superfluid of exciton - polaritons in a one - dimensional semiconductor microcavity.   polaritons are coherently injected into the microcavity by a laser pump with a suitably tailored spot profile.   an event horizon with a large analog surface gravity is created by inserting a defect in the polariton flow along the cavity plane.   experimentally observable signatures of the analog hawking radiation are identified in the scattering of phonon wavepackets off the horizon, as well as in the spatial correlation pattern of quantum fluctuations of the polariton density.   the potential of these table - top optical systems as analog models of gravitational physics is quantitatively confirmed by numerical calculations using realistic parameters for state - of - the - art devices.
the wisconsin h - alpha mapper ( wham ) is a high throughput fabry - perot facility developed specifically to detect and explore the warm, ionized component of the interstellar medium at high spectral resolution.   it began operating at kitt peak, arizona in 1997 and has recently completed the wham northern sky survey ( wham - nss ), providing the first global view of the distribution and kinematics of the warm, diffuse h  ii in the milky way.   this h@xmath0 survey reveals a complex spatial and kinematic structure in the warm ionized medium and provides a foundation for studies of the temperature and ionization state of the gas, the spectrum and strength of the ionizing radiation, and its relationship to other components of the interstellar medium and sources of ionization and heating within the galactic disk and halo.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we provide a systematic quantitative description of the structure of edge states and magnetosubband evolution in hard wall quantum wires in the integer quantum hall regime.   our calculations are based on the self - consistent green s function technique where the electron- and spin interactions are included within the density functional theory in the local spin density approximation.   we analyze the evolution of the magnetosubband structure as magnetic field varies and show that it exhibits different features as compared to the case of a smooth confinement. in   particularly, in the hard - wall wire a deep and narrow triangular potential well ( of the width of magnetic length @xmath0 ) is formed in the vicinity of the wire boundary.   the wave functions are strongly localized in this well which leads to the increase of the electron density near the edges. because of the presence of this well, the subbands start to depopulate from the central region of the wire and remain pinned in the well region until they are eventually pushed up by increasing magnetic field.   we also demonstrate that the spin polarization of electron density as a function of magnetic field shows a pronounced double - loop pattern that can be related to the successive depopulation of the magnetosubbands.   in contrast to the case of a smooth confinement, in hard - wall wires the compressible strips do not form in the vicinity of wire boundaries and spatial spin separation between spin - up and spin - down states near edges is absent.
spherically symmetric thin - shell wormholes in the presence of a cosmological constant are constructed applying the cut - and - paste technique implemented by visser. using the darmois - israel formalism the surface stresses, which are concentrated at the wormhole throat,   are determined.   this construction allows one to apply a dynamical analysis to the throat, considering linearized radial perturbations around static solutions. for a large positive cosmological constant, i.e., for the schwarzschild - de sitter solution, the region of stability   is significantly increased, relatively to the null cosmological constant case, analyzed by poisson and visser. with a negative cosmological constant, i.e., the schwarzschild - anti de sitter solution,   the region of stability is decreased. in particular, considering static solutions with a generic cosmological constant, the weak and dominant energy conditions are violated, while for @xmath0 the null and strong energy conditions are satisfied. the surface pressure of the static solution is strictly positive for the schwarzschild and schwarzschild - anti de sitter spacetimes, but takes negative values, assuming a surface tension in the schwarzschild - de sitter solution, for high values of the cosmological constant and the wormhole throat radius.
supersymmetric quantum hall liquids are constructed on a noncommutative superplane.   we explore a supersymmetric formalism of the landau problem. in the lowest landau level, there appear spin - less bosonic states and spin-1/2 down fermionic states, which exhibit a super - chiral property.   it is shown the laughlin wavefunction and topological excitations have their superpartners.   similarities between supersymmetric quantum hall systems and bilayer quantum hall systems are discussed.
many studies of the solar corona have shown that the observed x - ray luminosity is well correlated with the total unsigned magnetic flux. in this paper we present results from the extensive numerical modeling of active regions observed with the _ solar and heliospheric observatory _ ( _ soho _ ) extreme ultraviolet telescope ( eit ), the _ yohkoh _ soft x - ray telescope ( sxt ), and the _ soho _ michelson doppler imager ( mdi ).   we use potential field extrapolations to compute magnetic field lines and populate these field lines with solutions to the hydrostatic loop equations assuming steady, uniform heating.   our volumetric heating rates   are of the form @xmath0, where @xmath1 is the magnetic field strength averaged along a field line and @xmath2 is the loop length. comparisons between the observed and simulated emission for 26 active regions suggest that coronal heating models that scale as @xmath3 are in the closest argreement the observed emission at high temperatures.   the field - braiding reconnection model of parker, for example, is consistent with our results.   we find, however, that the integrated intensities alone are insufficent to uniquely determine the parameterization of the volumetric heating rate.   visualizations of the emission are also needed.   we also find that there are significant discrepancies between our simulation results and the lower temperature emission observed in the eit channels.
resonant production of a light, narrow techni - rho, followed by the decay @xmath0 has been proposed as an explanation of the @xmath1 excess observed by cdf.   if the @xmath2 decays to @xmath3 rather than to jets, subsequent leptonic @xmath4 decay leads to @xmath5, a final state that will be picked up by standard model @xmath6 higgs searches.   we point out that, for the same range of technicolor parameters required to fit the cdf @xmath1 excess, the correlated @xmath7 technicolor signal can have strength comparable to that of an intermediate - mass standard model higgs boson, and therefore could be visible at the tevatron or lhc.
massive star clusters observed in galaxy mergers are often suggested to be progenitors of globular clusters. to study this hypothesis  , we performed the highest resolution simulation of a gas - rich galaxy merger so far.   the formation of massive star clusters of @xmath0 to @xmath1  m@xmath2, triggered by the galaxy interaction, is directly resolved in this model.   we show that these clusters are tightly bound structures with little net rotation, due to evolve into compact long - lived stellar systems.   massive clusters formed in galaxy mergers are thus robust candidates for progenitors of long - lived globular clusters.   the simulated cluster mass spectrum is consistent with theory and observations.   tidal dwarf galaxies of @xmath3  m@xmath2 can form at the same time, and appear to be part of a different class of objects, being more extended and rotating.   globular clusters : general  galaxies : star clusters  galaxies : interactions
recent studies of galactic nuclei suggest that most galaxies are seeded by super - massive black holes which power the central nucleus. in this picture  , the proto - galactic object is likely to have undergone a very active phase during which the surrounding medium was shocked and heated up to very high temperatures.   we predict the cosmological effects of this scenario in terms of the thermal and kinetic sunyaev - zeldovich distortions induced on galactic scales by a population of proto - galaxies.   these predictions are compared to the observational limit on the mean compton distortion set by the cobe - firas instrument.   this enables us to derive tight constraints on the fraction of proto - galaxies seeded by super - massive black holes as well as on the black hole - to - spheroid mass ratio.   finally, we estimate the contribution of such a population to the angular power spectrum of the cosmic microwave background temperature anisotropies on very small angular scales ( @xmath0 ).
while past research in answer - set programming ( asp ) mainly focused on theory, asp solver technology, and applications, the present work situates itself in the context of a quite recent research trend : _ development support for asp. _ in particular, we propose to augment answer - set programs with additional meta - information formulated in a dedicated annotation language, called.   this language allows the grouping of rules into coherent blocks and to specify language signatures, types, pre- and postconditions, as well as unit tests for such blocks. while these annotations are invisible to an asp solver, as they take the form of program comments, they can be interpreted by tools for documentation, testing, and verification purposes, as well as to eliminate sources of common programming errors by realising syntax checking or code completion features. to demonstrate its versatility, we introduce two such tools, viz.   ( i ) , for generating an html documentation for a program based on the annotated information, and ( ii ) , for running and monitoring unit tests on program blocks.   is also exploited in the @xmath0system, an integrated development environment for asp based on eclipse.       answer - set programming, program annotations, documentation, unit testing
the codalema experiment uses 6 large frequency bandwidth antennas of the nanay radio observatory decametric array ( france ). in a first configuration,   one antenna narrowed band filtered acting as trigger, with a 4 @xmath0 threshold above sky background - level, was used to tag any radio transient in coincidence on the antenna array.   recently, the addition of 4 particle detectors allowed us to observe cosmic ray events in coincidence with antennas.   * keywords:*ultra high energy cosmic rays ; radiodetection.
we recall the main features of the @xmath0 ( tetrahedral ) symmetry in atomic nuclei and present realistic mean - field calculations supporting the existence such a symmetry all over the nuclear chart.   a few potential candidate - nuclei are investigated and the possible experimental signatures of the tetrahedral symmetry are also briefly discussed.
we introduce discrete systems in the form of straight ( infinite ) and ring - shaped chains, with two symmetrically placed nonlinear sites.   the systems can be implemented in nonlinear optics ( as waveguiding arrays ) and bec ( by means of an optical lattice ). a full set of exact analytical solutions for symmetric, asymmetric, and antisymmetric localized modes is found, and their stability is investigated in a numerical form.   the symmetry - breaking bifurcation ( sbb ), through which the asymmetric modes emerge from the symmetric ones, is found to be of the subcritical type.   it is transformed into a supercritical bifurcation if the nonlinearity is localized in relatively broad domains around two central sites, and also in the ring of a small size, i.e., in effectively nonlocal settings.   the family of antisymmetric modes does not undergo bifurcations, and features both stable and unstable portions.   the evolution of unstable localized modes is investigated by means of direct simulations.   in particular, unstable asymmetric states, which exist in the case of the subcritical bifurcation, give rise to breathers oscillating between the nonlinear sites, thus restoring an effective dynamical symmetry between them.
we present the first mid - infrared interferometric measurements of fu orionis.   we clearly resolve structures that are best explained with an optically thick accretion disk.   a simple accretion disk model fits the observed sed and visibilities reasonably well and does not require the presence of any additional structure such as a dusty envelope.   the inclination and also the position angle of the disk can be constrained from the multibaseline interferometric observations.   our disk model is in general agreement with most published near - infrared interferometric measurements. from the shape and strength of the 8 - 13@xmath0 m spectrum the dust composition of the accretion disk   is derived for the first time.   we conclude that most dust particles are amorphous and already much larger than those typically observed in the ism.   although the high accretion rate of the system provides both, high temperatures out to large radii and an effective transport mechanism to distribute crystalline grains, we do not see any evidence for crystalline silicates neither in the total spectrum nor in the correlated flux spectra from the inner disk regions.   possible reasons for this non - detection are mentioned.   all results are discussed in context with other high - spatial resolution observations of fu ori and other fu ori objects.   we also address the question whether fu ori is in a younger evolutionary stage than a classical ttauri star.
we describe the generation of single - band point source catalogues from submillimetre _ herschel_spire observations taken as part of the science demonstration phase of the _ herschel _ multi - tiered extragalactic survey ( hermes ).   flux densities are found by means of peak - finding and the fitting of a gaussian point - response function. with highly - confused images,   careful checks must be made on the completeness and flux density accuracy of the detected sources.   this is done by injecting artificial sources into the images and analysing the resulting catalogues. measured flux densities at which 50 per cent of injected sources result in good detections at ( 250, 350, 500)@xmath0 m range from ( 11.6, 13.2, 13.1)mjy to ( 25.7, 27.1, 35.8)mjy, depending on the depth of the observation ( where a ` good'detection is taken to be one with positional offset less than one full - width half - maximum of the point - response function, and with the measured flux density within a factor of 2 of the flux density of the injected source ).   this paper acts as a reference for the 2010 july hermes public data release.       catalogues   submillimetre : galaxies  methods : data analysis  galaxies : photometry
one - loop corrections to @xmath0 photoproduction near threshold have been investigated by using the approximation that all relevant transition amplitudes are calculated from the tree diagrams of effective lagrangians. with the parameters constrained by the data of @xmath1, @xmath2, and @xmath3 reactions, it is found that the one - loop effects due to the intermediate @xmath4 and @xmath5 states can significantly change the differential cross sections and spin observables.   the results from this exploratory investigation suggest strongly that the coupled - channel effects should be taken into account in extracting reliable resonance parameters from the data of vector meson photoproduction in the resonance region.
we use a sample of 262 spectroscopically confirmed star - forming galaxies at redshifts @xmath0 to compare h@xmath1, uv, and ir star - formation - rate diagnostics and to investigate the dust properties of the galaxies. at these redshifts, the h@xmath1 line shifts to the @xmath2-band. by comparing @xmath2-band photometry to   underlying stellar population model fits to other uv, optical, and near - infrared data, we infer the h@xmath1 flux for each galaxy.   we obtain the best agreement between h@xmath1- and uv - based sfrs if we assume that the ionized gas and stellar continuum are reddened by the same value and that the calzetti attenuation curve is applied to both. aided with mips 24@xmath3 m data,   we find that an attenuation curve steeper than the calzetti curve is needed to reproduce the observed ir / uv ratios of galaxies younger than 100myr. furthermore, using the bolometric star - formation rate inferred from the uv and mid - ir data ( sfr@xmath4+sfr@xmath5 ), we calculated the conversion between the h@xmath1 luminosity and sfr to be @xmath6 for a salpeter imf, which is consistent with the @xcite conversion.   the derived conversion factor is independent of any assumption of the dust correction and is robust to stellar population model uncertainties.
we present the first time - series study of the ultra - faint dwarf galaxy hercules. using a variety of telescope / instrument facilities we secured about 50 @xmath0 and 80 @xmath1 epochs.   these data allowed us to detect and characterize 10 pulsating variable stars in hercules.   our final sample includes 6 fundamental - mode ( ab - type ) and 3 first overtone ( c - type ) rr lyrae stars, and one anomalous cepheid.   the average period of the ab - type rr lyrae stars, @xmath2p@xmath3=0.68 d ( @xmath4 = 0.03 d ), places hercules in the oosterhoff ii group, as found for almost the totality of the ultra - faint dwarf galaxies investigated so far for variability.   the rr lyrae stars were used to obtain independent estimates of the metallicity, reddening and distance to hercules, for which we find : @xmath5=-2.30\pm0.15 $ ] dex, @xmath6 mag, and @xmath7 mag, in good agreement with the literature values.   we have obtained a @xmath8 color - magnitude diagram ( cmd ) of hercules that reaches @xmath9 25 mag and extends beyond the galaxy s half - light radius over a total area of @xmath10.   the cmd and the rr lyrae stars indicate the presence of a population as old and metal - poor as ( at least ) the galactic globular clusters m68.
we give a rigorous derivation of a theorem showing that charged particles in an arbitrary electromagnetic field with at least one ignorable spatial coordinate remain forever tied to a given magnetic - field line.   such a situation contrasts the significant motions normal to the magnetic field that are expected in most real three - dimensional systems.   it is pointed out that, while the significance of the theorem has not been widely appreciated, it has important consequences for a number of problems and is of particular relevance for the acceleration of cosmic rays by shocks.
epsilon - near - zero ( enz ) materials, including artificial metamaterials, have been advanced to mold laser beams and antenna - mediated radiated waves. here   we propose an efficient method to control ohmic losses inherent to natural enz materials by the assembly of subwavelength structures in a nonperiodic matrix constituting an enz metacoating.   implemented over plano - concave transparent substrates whose radius can be of only a few wavelengths, enz surface - relief elements demonstrate to adequately shape a plane wave into highly localized fields. furthermore, our proposal provides an energy efficiency even higher than an ideally - lossless all - enz plano - concave lens.   our procedure is satisfactory to generate aberration - free nonparaxial focused waves and accelerating beams in miniaturized spaces.   nonparaxial beam shaping, epsilon - near - zero materials, subwavelength structures.
we report the results of @xmath0 and @xmath1 observations of the x  ray source 1e  1743.12843, located in the region of the galactic center, performed between 1993 and 1998.   observations spanning almost twenty years show that 1e  1743.12843 is a persistent x  ray source, most likely powered by accretion onto a compact galactic object.   the absence of periodic pulsations and the relatively soft x  ray spectrum favour a low mass x  ray binary containing a neutron star.   however, no type  i x  ray bursts have been observed in more than 650 ks of observations, leaving other interpretations possible.   # 1to 0pt#1 # 1#2d # 1 d # 2 #1_#1 #1 # 2 a&a, # 1, # 2 # 1 # 2 mnras, # 1, # 2 # 1 # 2 apj, # 1, # 2 # 1 # 2 aj, # 1, # 2 # 1 # 2 nature, # 1, # 2 # 1 # 2 pasj, # 1, # 2    
the 1998 outburst of xte j1550@xmath0564 started with a hard x - ray spike, rising in less than a day and declining after 3 - 4 days ; at the same time, the soft x - ray flux was rising with a longer timescale ( @xmath1 days ).   we suggest that the soft and the initial hard x - ray emission are produced by two different components of the accretion flow : a higher angular momentum flow, which forms the disk, and a lower angular momentum flow feeding the hot inner region.   thus, we argue that the onset of the outburst is determined by an increased mass transfer rate from the companion star, but the outburst morphology is also determined by the distribution of specific angular momentum in the accreting matter. in xte j1550@xmath0564,   we attribute the initial, impulsive low angular momentum accretion to the breaking down of magnetic confinement by the magnetically active secondary star.   we show that a hard x - ray spike is seen at the onset of an outburst in other bhcs.
we qualitatively study the effects of gravitational microlensing on our view of unresolved extragalactic star formation regions. using a general gravitational microlensing configuration, we perform a number of simulations that reveal that specific imprints of the star forming region are imprinted, both photometrically and spectroscopically, upon observations.   such observations have the potential to reveal the nature and size of these star forming regions, through the degree of variability observed in a monitoring campaign, and hence resolve the star formation regions in distant galaxies which are too small to be probed via more standard techniques.
in this work we consider the dynamical casimir effect for a massless scalar field  under dirichlet boundary conditions  between two concentric spherical shells.   we obtain a general expression for the average number of particle creation, for an arbitrary law of radial motion of the spherical shells, using two distinct methods : by computing the density operator of the system and by calculating the bogoliubov coefficients.   we apply our general expression to breathing modes : when only one of the shells oscillates and when both shells oscillate in or out of phase.   since our results were obtained in the framework of the perturbation theory, under resonant breathing modes they are restricted to a short - time approximation. *   * we also analyze the number of particle production and compare it with the results for the case of plane geometry.
i review several of the current issues in the theory of disk galaxy formation.   there is still much to be done, observationally and theoretically, before we can expect to approach an understanding of disk galaxies that is reliable enough to make robust predictions about the high redshift universe.
we discuss an extension to the chandrasekhar - fermi method for the evaluation of the mean magnetic field strength in molecular clouds to cases where the spatial orientation of the field is known.   we apply the results to m17, using previously published data.
an important aspect of astrophysical mhd turbulence research is developing diagnostics to connect simulations with the observable universe.   turbulent systems are by definition structurally complex in all fluid variables ( density, velocity, and magnetic field ), such that they must be described statistically. by developing and applying diagnostic tools to simulation data,   it is possible to interpret empirical laws for the statistical properties of observed systems in terms of fundamental dynamical processes, and to identify and calibrate robust probes of physical parameters that can not be measured directly. using several different examples,   i describe how structural diagnostic analyses have already yielded significant insights into the nature of turbulent molecular clouds.   i review results from several different groups, and discuss directions for future diagnostics to enhance our understanding of cloud structure and constrain models of the evolutionary course that governs star formation.
chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport.   measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice.   however, not only chemistry, in this case diazonium chemistry, has an effect on the electron transport.   latter is also influenced by defects and dopants resulting from different processing steps.   here, we show that solvents used in the chemical reaction process change the transport properties. in more detail,   the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene.   furthermore, the isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport which might be difficult to distinguish from the effect of functionalization.   the results shown in this work demand a closer look on the influence of solvents used for chemical modification in order to understand their influence.
the cosmic - ray proton, helium, and muon spectra at small atmospheric depths of 4.5  28  g/@xmath0 were precisely measured during the slow descending period of the bess-2001 balloon flight.   the variation of atmospheric secondary particle fluxes as a function of atmospheric depth provides fundamental information to study hadronic interactions of the primary cosmic rays with the atmosphere.  ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,    atmospheric muon, cosmic - ray proton, cosmic - ray helium, atmospheric neutrino, superconducting spectrometer    95.85.ry, 96.40.-z, 96.40.tv
the composition - independent virial coefficients of a @xmath0-dimensional binary mixture of ( additive ) hard hyperspheres following from a recent proposal for the equation of state of the mixture [ santos, a., yuste, s. b., and lpez de haro, m., 1999, _ molec.   phys.   _, * 96 *, 1 ] are examined.   good agreement between theoretical estimates and available exact or numerical results is found for @xmath1, 3, 4 and @xmath2, except for mixtures whose components are very disparate in size.   a slight modification that remedies this deficiency is introduced and the resummation of the associated virial series is carried out, leading to a new proposal for the equation of state.   the case of binary hard - sphere mixtures ( @xmath3 ) is analyzed in some detail.
we investigate the marginally stable modes of the scalar ( vector ) perturbations in the ads soliton background coupled to electric field. in the probe limit, we find that the marginally stable modes can reveal the onset of the phase transitions of this model.   the critical chemical potentials obtained from this approach are in good agreement with the previous numerical or analytical results.   pacs numbers : 11.25.tq, 74.20.-z, 04.70.-s
the ads / qcd holographic wave function of basis light - front quantization ( blfq ) for vector meson @xmath0 is applied in this manuscript.   the exclusive production of @xmath0 in diffractive process is computed in dipole model with ads / qcd holographic wave function.   we use ip - sat and iim model in the calculation of the differential cross section of the dipole scattering off the proton.   the prediction of ads / qcd holographic wave function in blfq gives a good agreement to the experimental data.
we study spreading wave packets in a disordered nonlinear ladder with broken time - reversal symmetry induced by synthetic gauge fields.   the model describes the dynamics of interacting bosons in a disordered and driven optical ladder within a mean - field approximation.   the second moment of the wave packet @xmath0 grows subdiffusively with the universal exponent @xmath1 similar to the time - reversal case.   however, the prefactor @xmath2 is strongly modified by the field strength and shows a non - monotonic dependence. for a weak field,   the prefactor increases since time - reversal enhanced backscattering is suppressed. for strong fields   the spectrum of the linear wave equation reduces the localization length through the formation of gaps and narrow bands.   consequently the prefactor for the subdiffusive spreading law is suppressed.
several different methods have recently been proposed for calculating the motion of a point particle coupled to a linearized gravitational field on a curved background.   these proposals are motivated by the hope that the point particle system will accurately model certain astrophysical systems which are promising candidates for observation by the new generation of gravitational wave detectors.   because of its mathematical simplicity, the analogous system consisting of a point particle coupled to a scalar field provides a useful context in which to investigate these proposed methods. in this paper, we generalize the axiomatic approach of quinn and wald in order to produce a general expression for the self force on a point particle coupled to a scalar field following an arbitrary trajectory on a curved background.   our equation includes the leading order effects of the particle s own fields, commonly referred to as `` self force '' or `` radiation reaction '' effects.   we then explore the equations of motion which follow from this expression in the absence of non - scalar forces.
we investigate the influence of medium effects on the structure of hybrid stars, i.e.  neutron stars possessing a quark matter core.   we found that medium effects in quark matter reduce the extent of a pure quark matter phase in the interior of a hybrid star significantly in favor of a mixed phase of quark and hadronic matter. over a wide range of the strong coupling constant  which parameterizes the influence of medium effects   quark matter is able to exist at least in a mixed phase in the interior of neutron stars.   pacs : 12.38.mh, 26.60.+c    keywords : strange quark matter ; effective masses ; hybrid stars    _ institut fr theoretische physik, universitt giessen + 35392 giessen, germany _
we study numerically phonon modes of the classical one - dimensional frenkel - kontorova chain, in the regime of pinned phase characterized by the phonon gap and devil s staircase, as well as by a large number of states ( configurational excitations ), which energy splitting from the ground state is exponentially small.   we demonstrate, these states behave like disorder media : their phonon modes are _ exponentially _ localized, in contrast to the phonon modes in the ground state, where phonons are _ prelocalized _ only.   we demonstrate also, the phonon frequency spectrum of the ground state has an hierarchical structure, a direct manifestation of hierarchical spatial structure, found for the ground state of the fk chain in our recent work.
by observing the near - infrared spectrum of the quasar pg 1116 + 215 at @xmath0 and combining with the hst / fos spectrum, we obtained the relative strengths of three permitted o lines ( @xmath11304, @xmath18446, and @xmath111287 ) in a quasar for the first time.   the photon flux ratios of the o lines of the quasar were compared with those previously measured in a seyfert 1 and six narrow - line seyfert 1s.   no significant differences were found in the o line flux ratios between the quasar and the other seyferts, suggesting that the gas density in the o and fe line - emitting regions in the quasar is of the same order as those in low - luminosity agns.   it was also found that the line width of o @xmath111287 is significantly narrower than that of ly@xmath2, which is consistent with o and fe emission occurring in the partly ionized regions at the outermost portion of the broad - line region where velocities are small.
dynamical calculations are performed for all isomultiplets of the flavour antidecuplet to which the newly discovered pentaquark @xmath0 belongs.   the framework is a constituent quark model where the short - range interaction has a flavour - spin structure. in this model   the lowest pentaquarks have positive parity.   each antidecuplet member is described by a variational solution with the pauli principle properly taken into account. by fitting the mass of @xmath0 of minimal content @xmath1,   the mass of @xmath2, of minimal content @xmath3, is predicted at approximately 1960 mev.   the influence of the octet - antidecuplet mixing on the masses of the @xmath4 and 0 pentaquarks is considered within the same model and the role of the kinetic energy plus the hyperfine interaction in this mixing is pointed out.
i discuss the systematic modifications to the perturbative qcd factorization approach in high energy @xmath0, @xmath1 and @xmath2 reactions.   these include transverse momentum diffusion manifest in the cronin effect and a small increase in the dijet acoplanarity ; nuclear size enhanced power corrections that lead to shadowing in deeply inelastic scattering and suppression of single and double inclusive hadron production at forward rapidity at rhic but disappear as a function of the transverse momentum ; inelastic attenuation of the jet cross sections or jet quenching that persists to much higher @xmath3.
we find that the confinement potential of a few electron quantum dot can be tuned to significantly increase the overlap with certain quantum hall trial wave functions. besides manipulating inter - electron interaction  , this approach may prove useful in quantum point contact experiments, which involve narrow constrictions.
the steady - state structure of self - gravitating, magnetized accretion disks is studied using a set of self - similar solutions which are appropriate in the outer regions.   the disk is assumed to be isothermal and the magnetic field outside of the disk is treated in a phenomenological way. however, the internal field is determined self - consistently.   the behaviour of the solutions are investigated by changing the input parameters of the model, i.e. mass accretion rate, coefficients of viscosity and resistivity, and the magnetic field configuration.
based on the beijing - arizona - taiwan - connecticut ( batc ) and sloan digital sky survey ( sdss ) photometric data, we adopt seds fitting method to * evaluate the metallicity distribution for @xmath040, 000 main - sequence stars in the galaxy*. according to the derived photometric metallicities of these sample stars, we find that the metallicity distribution shift from metal - rich to metal - poor with the increase of distance from the galactic center. * the mean metallicity is about of @xmath1 dex in the outer halo and @xmath2 dex in the inner halo. the mean metallicity smoothly decreases from @xmath3 to @xmath4 in interval @xmath5 kpc  . the fluctuation in the mean metallicity with galactic longitude can be found in interval @xmath6 kpc.   there is a vertical abundance gradients d[fe   / h]/dz   @xmath7 dex kpc@xmath8@xmath9 for the thin disk ( @xmath10 kpc ). at distance @xmath11 kpc, where the thick disk stars are dominated, the gradients are about of @xmath12 dex kpc@xmath8@xmath9, it can be interpreted as a mixture of stellar population with different mean metallicities at all @xmath13 levels.   the vertical metallicity gradient is @xmath14 dex kpc@xmath8@xmath9 for the halo ( @xmath13 @xmath15 5 kpc ).   * so there is little or no metallicity gradient in the halo.       galaxy : structure - galaxy : metallicity - galaxy : formation.
surface critical phenomena and the related onset of goldstone modes probe the fundamental properties of the confining flux in quantum chromodynamics.   new ideas on surface roughening and their implications for lattice studies of quark confinement are presented.   problems with the oversimplified string description of the wilson flux sheet are discussed.
we take advantage of good atmospheric transparency and the availability of high quality instrumentation in the @xmath0 near - infrared atmospheric window to present a grid of f, g, k, and m spectral standards observed at high spectral resolution ( @xmath125,000 ).   in addition to a spectral atlas, we present a catalog of atomic line absorption features in the @xmath2 range.   the catalog includes a wide range of line excitation potentials, from 0 - 13 ev, arising from neutral and singly ionized species, most frequently those of fe i and ti i at low excitation, cri, fe i, and si i at moderate excitation, and c i, s i, and si i having relatively high excitation.   the spectra also include several prominent molecular bands from cn and feh. for the atomic species, we analyze trends in the excitation potential, line depth, and equivalent width across the grid of spectroscopic standards to identify temperature and surface gravity diagnostics near @xmath0.   we identify the line ratios that appear especially useful for spectral typing as those involving tii and c i or s i, which are temperature sensitive in opposite directions, and srii, which is gravity sensitive at all spectral types.   ascii versions of all spectra are available in the online version of the journal.
the phonon thermal conductivity in diamond nanowires ( dnw ) is studied by molecular dynamics simulation.   it is found that the thermal conductivity in narrower dnw is lower and does not show obvious temperature dependence ; a very small value ( about 2.0 w / m / k ) of thermal conductivity is observed in ultra - narrow dnw, which may be of potential applications in thermoelectric devices.   these two phenomena are probably due to the dominant surface effect and phonon confinement effect in narrow dnw.   our simulation reveals a high anisotropy in the heat transport of dnw. specifically, the thermal conductivity in dnw along  growth direction is about five times larger than that of  and  growth directions.   the anisotropy is believed to root in the anisotropic group velocity for acoustic phonon modes in dnw along three different growth directions.
photon modes have an important role in characterizing the quantum sources of light. proper coupling of various photon modes obtained in spontaneous parametric down conversion ( spdc ) process in optical fibers is essential to generate an effective source of entangled photons.   the two main pre - detection factors affecting the biphoton mode coupling in spdc are the pump beam focusing parameter and the crystal thickness.   we present the numerical and experimental results on the effect of pump focusing on conditional down - converted photon modes for a type - i bbo crystal.   we experimentally verify that biphoton coupling efficiency decreases asymptotically with pump beam focusing parameter.   we attribute this behaviour to ( a ) the asymmetry in the spatial distribution of down - converted photons with the pump beam focusing parameter and ( b ) the ellipticity of biphoton modes introduced due to the focusing of the pump beam.   we also show experimentally the ellipticity as well as quantify the asymmetry with the pump focusing parameter  . these results may be useful in selecting optimum conditions in the down - conversion process for generating efficient sources of entangled photons for quantum information applications.   biphoton modes, spdc, fiber coupling
automatic verification deals with the validation by means of computers of correctness certificates.   the related tools, usually called _ proof assistant _ or _ interactive provers _, provide an interactive environment for the creation of formal certificates whose correctness can be assessed in a purely automatic way.   such have applications both in mathematics, where certificates are proofs of theorems, and in computer science, where certificates testify the correctness of a given software with respect to its specification.
we consider the relation between three physical problems : 2d directed lattice random walks, ensembles of @xmath0 torus knots, and instanton ensembles in 5d sqed with one compact dimension in @xmath1 background and with 5d chern - simons term at the level one.   all these ensembles exhibit the critical behavior typical for the `` area+length+corners '' statistics of grand ensembles of 2d directed paths. using the combinatorial description,   we obtain an explicit expression of the generating function for @xmath2-narayana numbers which amounts to the new critical behavior in the ensemble of @xmath0 torus knots and in the ensemble of instantons in 5d sqed.   depending on the number of the nontrivial fugacities, we get either the critical point, or cascade of critical lines and critical surfaces. in the 5d gauge theory   the phase transition is of the 3rd order, while in the ensemble of paths and ensemble of knots it is typically of the 1st order.   we also discuss the relation with the integrable models.
we study the emergency of mutual cooperation in evolutionary prisoner s dilemma games when the players are located on a square lattice.   the players can choose one of the three strategies : cooperation ( @xmath0 ), defection ( @xmath1 ) or `` tit for tat '' ( @xmath2 ), and their total payoffs come from games with the nearest neighbors. during the random sequential updates the players adopt one of their neighboring strategies if the chosen neighbor has higher payoff.   we compare the effect of two types of external constraints added to the darwinian evolutionary processes. in both cases the strategy of a randomly chosen player is replaced with probability @xmath3 by another strategy. in the first case,   the strategy is replaced by a randomly chosen one among the two others, while in the second case the new strategy is always @xmath0. using generalized mean - field approximations and monte carlo simulations   the strategy concentrations are evaluated in the stationary state for different strength of external constraints characterized by the probability @xmath3.
we present a scheme for engineering the joint spectrum of photon pairs created via spontaneous parametric down conversion.   our method relies on customizing the poling configuration of a quasi - phase - matched crystal.   we use simulated annealing to find an optimized poling configuration which allows almost arbitrary shaping of the crystal s phase - matching function.   this has direct application in the creation of pure single photons  currently one of the most important goals of single - photon quantum optics.   we describe the general algorithm and provide code, written in ` c`++, that outputs an optimized poling configuration given specific experimental parameters.
we give a brief overview of our current theoretical understanding of ultra - relativistic heavy ion collision and the properties of super - hot nuclear matter.   we focus on several issues that have been discussed in connection with experimental results from the cern sps and from the relativistic heavy ion collider rhic.   we give an extrapolation of our current knowledge to lhc energies and ask which physics questions can be addressed at the lhc.
we address the use of maximum distance separable ( mds ) codes for distributed storage ( ds ) to enable efficient content delivery in wireless networks.   content is stored in a number of the mobile devices and can be retrieved from them using device - to - device communication or, alternatively, from the base station ( bs ).   we derive an analytical expression for the download delay in the hypothesis that the reliability state of the network is periodically restored.   our analysis shows that mds - coded ds can dramatically reduce the download time with respect to the reference scenario where content is always downloaded from the bs.
there is a recently discovered connection between the spectral theory of schr - dinger operators whose potentials exhibit aperiodic order and that of laplacians associated with actions of groups on regular rooted trees, as grigorchuk s group of intermediate growth.   we give an overview of corresponding results, such as different spectral types in the isotropic and anisotropic cases, including cantor spectrum of lebesgue measure zero and absence of eigenvalues.   moreover, we discuss the relevant background as well as the combinatorial and dynamical tools that allow one to establish the afore - mentioned connection.   the main such tool is the subshift associated to a substitution over a finite alphabet that defines the group algebraically via a recursive presentation by generators and relators.   = 0,4 mm = 16.00 cm = 22.00 cm = 0.12 in = 0.12 in
no mixed research of hybrid and fractional - order systems into a cohesive and multifaceted whole can be found in the literature.   this paper focuses on such a synergistic approach of the theories of both branches, which is believed to give additional flexibility and help the system designer.   it is part ii of two companion papers and focuses on fractional - order hybrid control.   specifically, two types of such techniques are reviewed, including robust control of switching systems and different strategies of reset control.   simulations and experimental results are given to show the effectiveness of the proposed strategies.   part i will introduce the fundamentals of fractional - order hybrid systems, in particular, modelling and stability of two kinds of such systems, i.e., fractional - order switching and reset control systems.
when recent experimental positronium ( ps ) formation cross sections in noble gases have been compared with the most up - to date theoretical studies, the agreement is qualitative, but not quantitative. in this paper   we re - examine this process and show that at low energies ps formation must be treated nonperturbatively.   we also look at ps formation with inner shell electrons.   ,    positron scattering, positronium formation, inner - shell ionization 34.85.+x,36.10.dr,32.80.hd
an index coding problem with @xmath0 messages has symmetric rate @xmath1 if all @xmath0 messages can be conveyed at rate @xmath1. in a recent work  , a class of index coding problems for which symmetric rate @xmath2 is achievable was characterised using special properties of the side - information available at the receivers. in this paper, we show a larger class of index coding problems ( which includes the previous class of problems ) for which symmetric rate @xmath2 is achievable. in the process, we also obtain a stricter necessary condition for rate @xmath2 feasibility than what is known in literature.
the multicast capacity of a directed network is closely related to the @xmath0-@xmath1 maximum flow, which is equal to the @xmath0-@xmath1 minimum cut capacity due to the max - flow min - cut theorem.   if the topology of a network ( or link capacities ) is dynamically changing or have stochastic nature, it is not so trivial to predict statistical properties on the maximum flow. in this paper  , we present a coding theoretic approach for evaluating the accumulate distribution of the minimum cut capacity of weighted random graphs.   the main feature of our approach is to utilize the correspondence between the cut space of a graph and a binary ldgm ( low - density generator - matrix ) code with column weight 2.   the graph ensemble treated in the paper is a weighted version of erds - rnyi random graph ensemble.   the main contribution of our work is a combinatorial lower bound for the accumulate distribution of the minimum cut capacity. from some computer experiments, it is observed that the lower bound derived here reflects the actual statistical behavior of the minimum cut capacity.
recent results comparing interacting galaxies to the mass - metallicity relation show that their nuclear oxygen abundances are unexpectedly low.   we present analysis of n - body / sph numerical simulations of equal - mass mergers that confirm the hypothesis that these underabundances are accounted for by radial inflow of low - metallicity gas from the outskirts of the two merging galaxies.   the underabundances arise between first and second pericenter, and the simulated abundance dilution is in good agreement with observations.   the simulations further predict that the radial metallicity gradients of the disk galaxies flatten shortly after first passage, due to radial mixing of gas.   these predictions will be tested by future observations of the radial metallicity distributions in interacting galaxies.
we study the quench dynamics of a bose - einstein condensate under a raman - assisted synthetic spin - orbit coupling. to model the dynamical process  , we adopt a self - consistent bogoliubov approach, which is equivalent to applying the time - dependent bogoliubov - de - gennes equations.   we investigate the dynamics of the condensate fraction as well as the momentum distribution of the bose gas following a sudden change of system parameters.   typically, the system evolves into a steady state in the long - time limit, which features an oscillating momentum distribution and a stationary condensate fraction. we investigate how different quench parameters such as the inter- and intra - species interactions and the spin - orbit - coupling parameters affect the condensate fraction in the steady state.   furthermore, we find that the time average of the oscillatory momentum distribution in the long - time limit can be described by a generalized gibbs ensemble with two branches of momentum - dependent gibbs temperatures.   our study is relevant to the experimental investigation of dynamical processes in a spin - orbit coupled bose - einstein condensate.
the detection of electromagnetic pulses from high energy showers is used as a means to search for ultra - high energy cosmic ray and neutrino interactions.   an approximate formula has been obtained to numerically evaluate the radio pulse emitted by a charged particle that instantaneously accelerates, moves at constant speed along a straight track and halts again instantaneously.   the approximate solution is applied to the particle track after dividing it in smaller subintervals.   the resulting algorithm ( often referred to as the zhs algorithm ) is also the basis for most of the simulations of the electric field produced in high energy showers in dense media. in this work, the electromagnetic pulses as predicted with the zhs algorithm are compared to those obtained with an exact solution of the electric field produced by a charged particle track.   the precise conditions that must apply for the algorithm to be valid are discussed and its accuracy is addressed.   this comparison is also made for electromagnetic showers in dense media.   the zhs algorithm is shown to describe cherenkov radiation and to be valid for most situations of interest concerning detectors searching for ultra - high energy neutrinos.   the results of this work are also relevant for the simulation of pulses emitted from air showers.
in 1922, kottler put forward the program to remove the gravitational potential, the metric of spacetime, from the _ fundamental _ equations in physics as far as possible.   he successfully applied this idea to newton s gravitostatics and to maxwell s electrodynamics, where kottler recast the field equations in premetric form and specified a metric - dependent constitutive law.   we will discuss the basics of the premetric approach and some of its beautiful consequences, like the division of universal constants into two classes.   we show that classical electrodynamics can be developed without a metric quite straightforwardly : the maxwell equations, together with a local and linear response law for electromagnetic media, admit a consistent premetric formulation.   kottler s program succeeds here without provisos. in kottler s   approach to gravity, making the theory relativistic, two premetric quasi - maxwellian field equations arise, but their field variables, if interpreted in terms of general relativity, do depend on the metric.   however, one can hope to bring the kottler idea to work by using the teleparallelism equivalent of general relativity, where the gravitational potential, the coframe, can be chosen in a premetric way.   _ since the notion of metric is a complicated one, which requires measurements with clocks and scales, generally with _ rigid    _ bodies, which themselves are systems of great complexity, it seems undesirable to take metric as fundamental, particularly for phenomena which are simpler and actually independent of it.   _    edmund whittaker ( 1953 )
one of the methods for studying the highest energy cosmic rays is to measure the fluorescence light emitted by the extensive air showers induced by them. to reconstruct a shower cascade curve from measurements of the number of photons arriving from the subsequent shower track elements it is necessary to take into account the multiple scatterings that photons undergo on their way from the shower to the detector.   in contrast to the earlier monte - carlo work, we present here an analytical method to treat the rayleigh and mie scatterings in the atmosphere.   the method consists in considering separately the consecutive generations of the scattered light. starting with a point light source in a uniform medium,   we then examine a source in a real atmosphere and finally - a moving source ( shower ) in it.   we calculate the angular distributions of the scattered light superimposed on the not scattered light registered from a shower at a given time.   the analytical solutions ( although approximate ) show how the exact numerical results should be parametrised what we do for the first two generations ( the contribution of the higher ones being small ). not allowing for the considered effect may lead to an overestimation of shower primary energy by @xmath0 and to an underestimation of the primary particle mass.   ultra high energy extensive air showers, cosmic rays, fluorescence light, shower reconstruction
we study the accretion on to the neutron star in be / x - ray binaries, using a 3d sph code and the data imported from a simulation by @xcite for a coplanar system with a short period ( @xmath0 ) and a moderate eccentricity @xmath1, which targeted the be / x - ray binary 4u0115 + 63. for simplicity  , we adopt the polytropic equation of state.   we find that a time - dependent accretion disc is formed around the neutron star regardless of the simulation parameters. in the long term  , the disc evolves via a two - stage process, which consists of the initial developing stage and the later developed stage.   the developed disc is nearly keplerian. in the short term  , the disc structure modulates with the orbital phase.   the disc shrinks at the periastron passage of the be star and restores its radius afterwards  . the accretion rate on to the neutron star is also phase dependent, but its peak is broader and much lower than that of the mass - transfer rate from the be disc, unless the polytropic exponent is as large as 5/3.   our simulations show that the truncated be disk model for be / x - ray binaries is consistent with the observed x - ray behaviour of 4u0115 + 63.       accretion, accretion discs  hydrodynamics  methods : numerical  binaries : general  stars : emission - line, be  x - rays : binaries
the far - red portion of the spectrum offers bright prospects for an accurate classification of cool stars, like the giant components of symbiotic stars.   the 84808740   region, free from telluric absorptions and where the gaia cornerstone mission by esa will record spectra for @xmath0 stars, is investigated on the base of available observed and synthetic spectral atlases.   we have identified and calibrated diagnostic line ratios useful to derive the effective temperature ( spectral type ) and gravity ( luminosity class ) for cool stars observed at spectral resolutions 10,000 @xmath1 20,000, bracketing that eventually chosen for gaia.
curtis - ingerman - morrow characterize response matrices for circular planar electrical networks as symmetric square matrices with row sums zero and non - negative circular minors. in this paper  , we study this positivity phenomenon more closely, from both algebraic and combinatorial perspectives. extending work of postnikov  , we introduce electrical positroids, which are the sets of circular minors which can simultaneously be positive in a response matrix.   we give a self - contained axiomatic description of these electrical positroids. in the second part of the paper,   we discuss a naturally arising example of a laurent phenomenon algebra, as studied by lam - pylyavskyy.   we investigate the clusters in this algebra, building off of initial work by kenyon - wilson, using an analogue of weak separation, as was originally introduced by leclerc - zelevinsky.
models for the formation and growth of structure in a cold dark matter dominated universe predict that galaxy halos should contain significant substructure. studies of the milky way, however, have yet to identify the expected few hundred sub - halos with masses greater than about @xmath0. here   we propose a test for the presence of sub - halos in the halos of galaxies.   we show that the structure of the tidal tails of ancient globular clusters is very sensitive to heating by repeated close encounters with the massive dark sub - halos.   we discuss the detection of such an effect in the context of the next generation of astrometric missions, and conclude that it should be easily detectable with the gaia dataset.   the finding of a single extended cold stellar stream from a globular cluster would support alternative theories, such as self - interacting dark matter, that give rise to smoother halos.
we study the finite temperature and density effects on beta decay rates to compute their contributions to nucleosynthesis in the early universe and compact stars.   we express nucleosynthesis parameters as a function of temperature and density in different astronomical systems of interest.   it is explicitly shown that the chemical potential in the core of supermassive and superdense stars affect beta decay and their helium abundance but the background contributions is still dependent on relative temperature.   we calculate this contribution for @xmath0it has been noticed that the acceptable background contribution are obtained for comparatively larger values of t as temperature plays a role of regulating parameter in an extremely dense system.
in the present work, we conduct large - scale orbital - free dft calculations to study the energetics of vacancy clustering in aluminum from electronic structure calculations.   the simulation domains considered in this study are as large as those containing a million atoms to accurately account for both the electronic structure and long - ranged elastic fields.   our results indicate that vacancy clustering is an energetically favorable mechanisms with positive binding energies for a range of vacancy clusters considered in the present study.   in particular, the @xmath0 vacancy hexagonal cluster lying in @xmath1 plane has a very large binding energy with the relaxed atomic structure representative of a prismatic dislocation loop.   this suggests that vacancy prismatic loops as small as those formed from 19 vacancies are stable, thus providing insights into the nucleation sizes of these defects in aluminum.   vacancy clustering, prismatic dislocation, electronic structure, real space, dislocation nucleation
in atomic force microscopy ( afm ) tip - surface interactions are usually considered as functions of the tip position only, so - called force curves.   however, tip - surface interactions often depend on the tip velocity and the past tip trajectory. here  , we introduce a compact and general description of these interactions appropriate to dynamic afm where the measurement of force is restricted to a narrow frequency band.   we represent the tip - surface interaction in terms of a force disk in the phase space of position and velocity.   determination of the amplitude dependence of tip - surface forces at a fixed static probe height allows for a comprehensive treatment of conservative and dissipative interactions.   we illuminate the fundamental limitations of force reconstruction with narrow band dynamic afm and we show how the amplitude dependence of the fourier component of the force at the tip oscillation frequency, gives qualitative insight into the detailed nature of the tip - surface interaction. with minimal assumptions   this amplitude dependence force spectroscopy allows for a quantitative reconstruction of the effective conservative tip - surface force as well as a position - dependent damping factor.   we demonstrate this reconstruction on simulated intermodulation afm data.   _ keywords _ : atomic force microscopy, measurement of force, mechanical resonators, mems / nems, dissipation, intermodulation
we consider the dynamical evolution of a disk of stars orbiting a central black hole. in particular, we focus on the effect of the stellar mass function on the evolution of the disk, using both analytic arguments and numerical simulations.   we apply our model to the ring of massive stars at @xmath0pc from the galactic center, assuming that the stars formed in a cold, circular disk, and find that our model requires the presence of a significant population of massive ( @xmath1m@xmath2 ) stars in order to explain the the observed eccentricities of 0.20.3.   moreover, in order to limit the damping of the heavier stars eccentricities, we also require fewer low - mass stars than expected from a salpeter mass function, giving strong evidence for a significantly `` top - heavy '' mass function in the rings of stars seen near to the galactic center.   we also note that the maximum possible eccentricities attainable from circular initial conditions at ages of @xmath3myr are around 0.40.5, and suggest that any rings of stars found with higher eccentricities were probably not formed from circular disks.
most of the thermodynamic analysis of ovens are focused on efficiency, but they need to behaves under real - life conditions, then the effectiveness of the ovens plays a crucial role in their design. in this paper   we present a thermodynamical model able to describe the temperature evolution in ovens, furnaces or kilns to harden, burn or dry different products and which provides a methodology to design these heating devices.   we use the required temperature evolution for each product and process as main ingredient in the methodology and procedure to design ovens and we place in the right role the efficiency criteria.   we use global energy balance equation for the oven under transient situation as the thermodynamic starting point for developing the model.   our approach is able to consider different configurations for these heating devices, or recirculating or open situations, etc.
a bose - einstein condensate trapped in a double - well potential, where atoms are incoupled to one side and extracted from the other, can in the mean - field limit be described by the nonlinear gross - pitaevskii equation ( gpe ) with a @xmath0 symmetric external potential. if the strength of the in- and outcoupling is increased two @xmath0 broken states bifurcate from the @xmath0 symmetric ground state. at this bifurcation   point a stability change of the ground state is expected.   however, it is observed that this stability change does not occur exactly at the bifurcation but at a slightly different strength of the in-/outcoupling effect.   we investigate a bose - einstein condensate in a @xmath0 symmetric double-@xmath1 potential and calculate the stationary states.   the ground state s stability is analysed by means of the bogoliubov - de gennes equations and it is shown that the difference in the strength of the in-/outcoupling between the bifurcation and the stability change can be completely explained by the norm - dependency of the nonlinear term in the gross - pitaevskii equation.    1    1    1    1    1
important observational results have been recently reported on the angular distributions of cosmic rays ( crs ) at all energies, calling into question the perception of crs a decade ago.   these results together with their in - progress interpretations are summarized in this short overview paper, following the contribution presented at the european cosmic ray symposium.
we show that the running of the higgs - gaugino - higgsino couplings present in partial split supersymmetry can severely affect the neutrino masses generated through bilinear r - parity violation.   we find a working scenario where the predicted neutrino observables satisfy the experimental constraints when the running is neglected. after including the running, we show that already with a split supersymmetric scale of @xmath0 gev the atmospheric mass leaves the allowed experimental window, and that the solar mass leaves it even earlier, with a split supersymmetric scale of @xmath1 gev.   this shows that the correct prediction of neutrino observables in these models necessitates the inclusion of the running of these couplings.
we discuss the statistical properties of the volume of the nodal set of wave function for two paradigmatic model systems which we consider in arbitrary dimension @xmath0 : the cuboid as a paradigm for a regular shape with separable wave functions, planar random waves as an established model for chaotic wave functions in irregular shapes.   we give explicit results for the mean and variance of the nodal volume in arbitrary dimension, and for their limiting distribution.   for the mean nodal volume we calculate the effect of the boundary of the cuboid where dirichlet boundary conditions reduce the nodal volume compared to the bulk.   boundary effects for chaotic wave functions are calculated using random waves which satisfy a dirichlet boundary condition on a hyperplane.   + we put forward several conjectures what properties of cuboids generalise to general regular shapes with separable wave functions and what properties of random waves can be expected for general irregular shapes.   these universal features clearly distinct between the two cases.
we study diffusion on a substrate with permanent traps distributed with critical positional correlation, modeled by their placement on the perimeters of a critical percolation cluster. we perform a numerical analysis of the vibrational density of states and the largest eigenvalue of the equivalent scalar elasticity problem using the method of arnoldi and saad.   we show that the critical trap correlation increases the exponent appearing in the stretched exponential behavior of the low frequency density of states by approximately a factor of two as compared to the case of no correlations.   a finite size scaling hypothesis of the largest eigenvalue is proposed and its relation to the density of states is given.   the numerical analysis of this scaling postulate leads to the estimation of the stretch exponent in good agreement with the density of states result.
we consider the problem of reconstruction of dielectrics from blind backscattered experimental data.   experimental data were collected by a device, which was built at university of north carolina at charlotte.   this device sends electrical pulses into the medium and collects the time resolved backscattered data on a part of a plane.   the spatially distributed dielectric constant @xmath0 is the unknown coefficient of a wave - like pde.   this coefficient is reconstructed from those data in blind cases. to do this,   a globally convergent numerical method is used.    * keywords * : coefficient inverse problem ( cip ), finite element method, globally convergent numerical method for cip, experimental backscattered data.   * ams classification codes : * 65n15, 65n30, 35j25.
a deep underwater cherenkov telescope has been operating since 1993 in stages of growing size at 1.1 km depth in lake baikal.   the key component of the telescope is the optical module ( om ) which houses the highly sensitive phototube _   quasar-370_. we describe design and parameters of the _   quasar-370 _, the layout of the optical module, the front - end electronics and the calibration procedures, and present selected results from the five - year operation underwater. also, future developments with respect to a telescope consisting from several thousand oms are discussed.   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   .
we studied the ground and excited states of @xmath0c based on variational calculations after spin - parity projection in a framework of antisymmetrized molecular dynamics(amd ).   the calculations systematically reproduce various experimental data.   it was found that the sub - shell closure and @xmath1-limit @xmath2 cluster components are contained in the ground state, while various @xmath2 cluster structures develop in the excited states.   we discussed effects of @xmath3 breaking and show the importance of coexistence of the cluster and shell - model - like aspects.
once superpartners are discovered at colliders, the next challenge will be to determine the parameters of the supersymmetric lagrangian.   we illustrate how the relative phases of the gluino, @xmath0, and @xmath1 gauginos and the higgsino mass parameter @xmath2 can be measured at a hadron collider without ad hoc assumptions about the underlying physics, focusing on fermilab.   we also discuss how the gluino and lsp masses can be measured.    #   10= 0=0 1= 1=1 0>1 # 1 /
this talk serves as an introduction to higher twist effects in nuclei.   we want to discuss how perturbative qcd can be applied to processes involving heavy nuclei by taking into account multiple scattering.   * higher twist effects in nuclei * + r.  j.  fries + _ department of physics, duke university + box 90305, durham, nc 27708, usa + _ _ institute for theoretical physics, university of regensburg, + 93040 regensburg, germany + _
catalyzed symmetry breaking arises from a parametric enhancement of critical fluctuations independently of the coupling strength.   symmetry - breaking fermionic long - range fluctuations exhibit such an enhancement on negatively curved spaces, as is known from mean - field studies.   we study gravitational catalysis from the viewpoint of the functional renormalization group using the @xmath0 gross - neveu model as a specific example.   we observe gravitational catalysis towards a phase of broken discrete chiral symmetry both on a maximally symmetric ( ads ) and on a purely spatially curved manifold for constant negative curvature ( lobachevsky plane ). the resulting picture for gravitational catalysis obtained from the renormalization flow is closely related to that of magnetic catalysis.   as an application, we estimate the curvature required for subcritical systems of finite length to acquire a gravitionally catalyzed gap.
we provide evidence for a high precision model - independent low momentum nucleon - nucleon interaction. performing a momentum - space renormalization group decimation, we find that the effective interactions constructed from various high precision nucleon - nucleon interaction models, such as the paris, bonn, nijmegen, argonne, cd bonn and idaho potentials, are identical.   this model - independent low momentum interaction, called @xmath0, reproduces the same phase shifts and deuteron pole as the input potential models, without ambiguous assumptions on the high momentum components, which are not constrained by low energy data and lead to model - dependent results in many - body applications.   @xmath0 is energy - independent and does not necessitate the calculation of the brueckner @xmath1 matrix.    _   pacs : _ 21.30.cb ; 21.60.-n ; 21.30.fe ; 11.10.hi + _ keywords : _ nucleon - nucleon interaction ; effective interactions ; renormalization group   ,   ,   ,
we investigate rectification of a low - frequency ac bias in y - junctions of one - channel luttinger liquid wires with repulsive electron interaction.   rectification emerges due to three scatterers in the wires.   we find that it is possible to achieve a higher rectification current in a y - junction than in a single wire with an asymmetric scatterer at the same interaction strength and voltage bias.   the rectification effect is the strongest in the absence of the time - reversal symmetry. in that case  , the maximal rectification current can be comparable with the total current @xmath0 even for low voltages, weak scatterers and modest interaction strength. in a certain range of low voltages,   the rectification current can grow as the voltage decreases.   this leads to a bump in the @xmath1-@xmath2 curve.
distributions derived from non - extensive tsallis statistics are closely connected with dynamics described by a nonlinear fokker - planck equation.   the combination shows promise in describing stochastic processes with power - law distributions and superdiffusive dynamics.   we investigate intra - day price changes in the s&p500 stock index within this framework by direct analysis and by simulation.   we find that the power - law tails of the distributions, and the index s anomalously diffusing dynamics, are very accurately described by this approach.   our results show good agreement between market data, fokker - planck dynamics, and simulation.   thus the combination of the tsallis non - extensive entropy and the nonlinear fokker - planck equation unites in a very natural way the power - law tails of the distributions and their superdiffusive dynamics.
a high resolution ( @xmath0 ), very high @xmath1 ( @xmath2 ) spectrum of the metal - poor turnoff star has been obtained in connection with the commissioning of uves at vlt / kueyen. using both 1d hydrostatic and 3d hydrodynamical model atmospheres,   the lithium isotope ratio has been estimated from the 670.8 nm line by means of spectral synthesis.   the necessary stellar line broadening ( 1d : macroturbulence + rotation, 3d : rotation ) has been determined from unblended,  and  lines.   the 3d line profiles agree very well with the observed profiles, including the characteristic line asymmetries.   both the 1d and 3d analyses reveal a possible detection of  in, @xmath3{li}/\element{li}}= 0.02\pm0.01 $ ] ( @xmath4 ).   it is discussed if the smaller amount of  in than in the similar halo star could be due to differences in stellar mass and/or metallicity or whether it may reflect an intrinsic scatter of /  in the ism at a given metallicity.
the effects of gluon radiation by charm quarks on the transport coefficients _ e.g. _ drag, longitudinal and transverse diffusion and shear viscosity have been studied within the ambit of perturbative quantum chromodynamics ( pqcd ) and kinetic theory.   we found that while the soft gluon radiation has substantial effects on the transport coefficients of the charm quarks in the quark gluon plasma its effects on the equilibrium distribution function is insignificant.
the canonical answer to the question posed is  yes. "  tacitly assuming that quantum theory and the concept of spacetime are to be unified by ` quantizing'a theory of gravitation.   yet, instead, one may ponder : could quantum mechanics arise as a coarse - grained reflection of the atomistic nature of spacetime?  we speculate that this may indeed be the case.   we recall the similarity between evolution of classical and quantum mechanical ensembles, according to liouville and vonneumann equation, respectively.   the classical and quantum mechanical equations are indistinguishable for objects which are free or subject to spatially constant but possibly time dependent, or harmonic forces, if represented appropriately.   this result suggests a way to incorporate anharmonic interactions, including fluctuations which are tentatively related to the underlying discreteness of spacetime.   being linear and local at the quantum mechanical level, the model offers a decoherence and natural localization mechanism.   however, the relation to primordial deterministic degrees of freedom is nonlocal.
the yields and velocity distributions of heavy residues and fission fragments from the reaction of 20 mev / nucleon @xmath0au + @xmath1zr have been measured using the msu a1200 fragment separator.   a bimodal distribution of residues is observed, with one group, resulting from peripheral collisions, having fragment mass numbers a=160200 while the other group, resulting from   hard"collisions, has a=120160.   this latter group of residues can be distinguished from fission fragments by their lower velocities. a model combining deep - inelastic transfer and incomplete fusion for the primary interaction stage and a statistical evaporation code for the deexcitation stage has been used to describe the properties of the product distributions.   @xmath2,   ,    @xmath3,   , and   .    nuclear reactions, incomplete fusion, deep inelastic scattering 25.70.-z, 25.70.jj, 25.70.lm
we consider the problem of evaluating the entanglement of non - gaussian mixed states generated by photon subtraction from entangled squeezed states.   the entanglement measures we use are the negativity and the logarithmic negativity.   these measures possess the unusual property of being computable with linear algebra packages even for high - dimensional quantum systems.   we numerically evaluate these measures for the non - gaussian mixed states which are generated by photon subtraction with on / off photon detectors.   the results are compared with the behavior of certain operational measures, namely the teleportation fidelity and the mutual information in the dense coding scheme.   it is found that all of these results are mutually consistent, in the sense that whenever the enhancement is seen in terms of the operational measures, the negativity and the logarithmic negativity are also enhanced.
we review the development and practical uses of a generalized maupertuis least action principle in classical mechanics, in which the action is varied under the constraint of fixed energy for the trial trajectory.   the original maupertuis ( euler - lagrange ) principle constrains the energy at every point along the trajectory.   the generalized maupertuis principle is equivalent to hamilton s principle.   reciprocal principles are also derived for both the generalized maupertuis and the hamilton principles.   the reciprocal maupertuis principle is the classical limit of schrdinger s variational principle of wave mechanics, and is also very useful to solve practical problems in both classical and semiclassical mechanics, in complete analogy with the quantum rayleigh - ritz method.   classical, semiclassical and quantum variational calculations are carried out for a number of systems, and the results are compared.   pedagogical as well as research problems are used as examples, which include nonconservative as well as relativistic systems.  ... the most beautiful and important    discovery of mechanics. "
mass accretion is the key factor for evolution of galaxies.   it can occur through secular evolution, when gas in the outer parts is driven inwards by dynamical instabilities, such as spirals or bars.   this secular evolution proceeds very slowly when spontaneous, and can be accelerated when triggered by companions.   accretion can also occur directly through merging of small companions, or more violent interaction and coalescence.   we discuss the relative importance of both processes, their time - scale and frequency along a hubble time.   signatures of both processes can be found in the milky way.   it is however likely that our galaxy had already gathered the bulk of its mass about 8 - 10 gyr ago, as is expected in hierarchical galaxy formation scenarios.
field theories whose full action is lorentz invariant ( or diffeomorphism invariant ) can exhibit superluminal behaviors through the breaking of local lorentz invariance.   quantum induced superluminal velocities are well - known examples of this effect.   the issue of the causal behavior of such propagations is somewhat controversial in the literature and we intend to clarify it. we provide a careful analysis of the meaning of causality in classical relativistic field theories, and we stress the role played by the cauchy problem and the notions of chronology and time arrow.   we show that superluminal behavior threaten causality only if a prior chronology on spacetime is chosen. in the case where superluminal propagations occur, however, there is at least two non conformally related metrics on spacetime and thus two available notions of chronology.   these two chronologies are on equal footing and it would thus be misleading to choose _ ab initio _ one of them to define causality. rather, we provide a formulation of causality in which no prior chronology is assumed.   we argue this is the only way to deal with the issue of causality in the case where some degrees of freedom propagate faster than others.   we actually show that superluminal propagations do not threaten causality. as an illustration of these conceptual issues, we consider two field theories, namely k - essences scalar fields and bimetric theories of gravity, and we derive the conditions imposed by causality.   we discuss various applications such as the dark energy problem, mond - like theories of gravity and varying speed of light theories.
we propose a model to describe the quasistatic shearing of dry granular materials, which notably captures the differences in velocity profiles recently observed in 2 and 3-d couette flow experiments. in our scheme  , the steady - state flow is due to the intermittent motion of particle clusters moving together with the wall.   the motion of a cluster is associated with the transient formation of a fracture inside the sheared pack.   the model is based on the existence of a persistence length for the fractures, which imposes a self - similar structure on the clusters. through a probabilistic approach  , we can evaluate the rate of appearance of a cluster of a given size and obtain a prediction for the average velocity profiles.   we also predict the existence of large stress fluctuations at the moving wall, which characteristics are in good agreement with experimental data.
in order to extend the recently proposed monte carlo hamiltonian to many - body systems, we suggest to concept of a stochastic basis. we apply it to the chain of @xmath0 coupled anharmonic oscillators.   we compute the spectrum of excited states in a finite energy window and thermodynamical observables free energy, average energy, entropy and specific heat in a finite temperature window. comparing the results of the monte carlo hamiltonian with standard lagrangian lattice calculations, we find good agreement  . however, the monte carlo hamiltonian results show less fluctuations under variation of temperature.   ,   ,   ,
the skewing factor, defined as the ratio of the imaginary parts of the amplitudes @xmath0 is extracted for the first time from the data using recent deeply virtual compton scattering ( dvcs ) and the inclusive inelastic cross section measurements at desy - hera.   the results values are compared to theoretical predictions for nlo qcd and the colour dipole approach.    * extraction of the skewing factor from the dis / dvcs ratio. * +    l. favart@xmath1, m.v.t.   machado@xmath2 and l.  schoeffel@xmath3 +   + @xmath2 high energy physics phenomenology group, gfpae, if - ufrgs + caixa postal 15051, cep 91501 - 970, porto alegre, rs, brazil + @xmath3 ce saclay, dapnia - spp, 91191, gif - sur - yvette, france +
recently bender, brody, jones and meister found that in the quantum brachistochrone problem the passage time needed for the evolution of certain initial states into specified final states can be made arbitrarily small, when the time - evolution operator is taken to be non - hermitian but @xmath0-symmetric.   here we demonstrate that such phenomena can also be obtained for non - hermitian hamiltonians for which @xmath1-symmetry is completely broken, i.e. dissipative systems.   we observe that the effect of a tunable passage time can be achieved by projecting between orthogonal eigenstates by means of a time - evolution operator associated to a non - hermitian hamiltonian.   it is not essential that this hamiltonian is @xmath1-symmetric.   pacs numbers : 03.65.xp, 03.65.ca, 03.65.-w, 11.30er
we study isospin effects in semi - peripheral collisions above the fermi energy by considering the symmetric @xmath0+@xmath0 and the asymmetric reactions @xmath0+@xmath1 over the incident energy range 52 - 74  a  mev. a microscopic transport model with two different parameterizations of the symmetry energy term   is used to investigate the isotopic content of pre - equilibrium emission and the n / z diffusion process.   simulations are also compared to experimental data obtained with the indra array and bring information on the degree of isospin equilibration observed in ni + au collisions. a better overall agreement between data and simulations   is obtained when using a symmetry term which linearly increases with nuclear density.
we describe an expansion of the solution of the wave equation in the de sitter  schwarzschild metric in terms of resonances. the main term in the expansion is due to a zero resonance.   the error term decays polynomially if we permit a logarithmic derivative loss in the angular directions and exponentially if we permit an @xmath0 derivative loss in the angular directions.
the construction and use of a dual radiator ring imaging erenkov ( rich ) detector is described.   this instrument was developed for the hermes experiment at desy which emphasises measurements of semi - inclusive deep - inelastic scattering.   it provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 gev, which is essential to these studies.   the instrument uses two radiators, @xmath0, a heavy fluorocarbon gas, and a wall of silica aerogel tiles.   the use of aerogel in a rich detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel.   a lightweight mirror was constructed using a newly perfected technique to make resin - coated carbon - fiber surfaces of optical quality.   the photon detector consists of 1934 photomultiplier tubes ( pmt ) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.   # 1#2#3#4#1 * # 2 *, ( # 3 ) ( # 4 )   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,    @xmath1   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,
the combination of the broad band coverage and moderate spectral resolution of the lecs and mecs instruments on - board bepposax allow the spectra of agn to be studied in unprecedented detail down to 0.1 kev.   we describe the calibration and the performance of the lecs and report on observations of low - energy absorption features in the spectra of both a low ( mcg-6 - 30 - 15 ) and a high luminosity ( 3c 273 ) agn.   these features provide important diagnostics on the location and nature of the material surrounding the agn.   a comparison of lecs and asca / sis low energy performance is also presented in the case of 3c 273.
we present results from a survey of the internal kinematics of 49 star - forming galaxies at @xmath0 in the candels fields with the keck / mosfire spectrograph ( sigma, survey in the near - infrared of galaxies with multiple position angles ).   kinematics ( rotation velocity @xmath1 and integrated gas velocity dispersion @xmath2 ) are measured from nebular emission lines which trace the hot ionized gas surrounding star - forming regions.   we find that by @xmath0, massive star - forming galaxies ( @xmath3 ) have assembled primitive disks : their kinematics are dominated by rotation, they are consistent with a marginally stable disk model, and they form a tully - fisher relation.   these massive galaxies have values of @xmath4 which are factors of 25 lower than local well - ordered galaxies at similar masses.   such results are consistent with findings by other studies.   we find that low mass galaxies ( @xmath5 ) at this epoch are still in the early stages of disk assembly : their kinematics are often supported by gas velocity dispersion and they fall from the tully - fisher relation to significantly low values of @xmath1.   this   kinematic downsizing " implies that the process(es ) responsible for disrupting disks at @xmath0 have a stronger effect and/or are more active in low mass systems. in conclusion,   we find that the period of rapid stellar mass growth at @xmath0 is coincident with the nascent assembly of low mass disks and the assembly and settling of high mass disks.
gene expression levels carry information about signals that have functional significance for the organism. using the gap gene network in the fruit fly embryo as an example,   we show how this information can be decoded, building a dictionary that translates expression levels into a map of implied positions.   the optimal decoder makes use of graded variations in absolute expression level, resulting in positional estimates that are precise to @xmath0 of the embryo s length.   we test this optimal decoder by analyzing gap gene expression in embryos lacking some of the primary maternal inputs to the network.   the resulting maps are distorted, and these distortions predict, with no free parameters, the positions of expression stripes for the pair - rule genes in the mutant embryos.
far - infrared _ spitzer _ observations of elliptical galaxies are inconsistent with simple steady state models of dust creation in red giant stars and destruction by grain sputtering in the hot interstellar gas at @xmath0 k. the flux at 24@xmath1 m correlates with optical fluxes, suggesting that this relatively hot dust is largely circumstellar. but fluxes at 70@xmath1 m and 160@xmath1 m do not correlate with optical fluxes.   elliptical galaxies with similar @xmath2 have luminosities at 70@xmath1 m and 160@xmath1 m ( @xmath3 and @xmath4 ) that vary over a factor @xmath5, implying an additional source of dust unrelated to that produced by ongoing local stellar mass loss.   neither @xmath6 nor @xmath7 correlate with the stellar age or metallicity.   optical line fluxes from warm gas at @xmath8 k correlate weakly with @xmath3 and @xmath4, suggesting that the dust may be responsible for cooling this gas.   many normal elliptical galaxies have emission at 70@xmath1 m that is extended to 510 kpc.   extended far - infrared emission with sputtering lifetimes of @xmath9 yrs is difficult to maintain by mergers with gas - rich galaxies.   instead, we propose that this cold dust is buoyantly transported from reservoirs of dust in the galactic cores which is supplied by mass loss from stars in the core.   intermittent energy outbursts from agns can drive the buoyant outflow.
we report on a scheme to improve the pointing stability of the first order beam diffracted by an acousto - optic modulator ( aom ). due to thermal effects inside the crystal, the angular position of the beam can change by as much as 1  mrad when the radio - frequency power in the aom is reduced to decrease the first order beam intensity.   this is done for example to perform forced evaporative cooling in ultracold atom experiments using far - off - resonant optical traps.   we solve this problem by driving the aom with two radio - frequencies @xmath0 and @xmath1.   the power of @xmath1 is adjusted relative to the power of @xmath0 to keep the total power constant. using this,   the beam displacement is decreased by a factor of twenty.   the method is simple to implement in existing experimental setups, without any modification of the optics.
we present fire/`gizmo ` hydrodynamic zoom - in simulations of isolated dark matter halos, two each at the mass of classical dwarf galaxies ( @xmath0 ) and ultra - faint galaxies ( @xmath1 ), and with two feedback implementations.   the resulting central galaxies lie on an extrapolated abundance matching relation from @xmath2 to @xmath3 without a break.   every host is filled with subhalos, many of which form stars.   our dwarfs with @xmath4 each have @xmath5 well - resolved satellites with @xmath6.   even our isolated ultra - faint galaxies have star - forming subhalos. if this is representative, dwarf galaxies throughout the universe should commonly host tiny satellite galaxies of their own.   we combine our results with the elvis simulations to show that targeting @xmath7 regions around nearby isolated dwarfs could increase the chances of discovering ultra - faint galaxies by @xmath8 compared to random halo pointings, and specifically identify the region around the phoenix dwarf galaxy as a good potential target.    the well - resolved ultra - faint galaxies in our simulations ( @xmath9 ) form within @xmath10 halos.   each has a uniformly ancient stellar population ( @xmath11 ) owing to reionization - related quenching.   more massive systems, in contrast, all have late - time star formation.   our results suggest that @xmath12 is a probable dividing line between halos hosting reionization  fossils " and those hosting dwarfs that can continue to form stars in isolation after reionization.       galaxies : dwarf  galaxies : star formation
a precision measurement of the proton flux in primary cosmic rays with rigidity from 1 gv to 1.8 tv is presented based on 300 million events.   the results show that the proton flux is smooth and exhibits no sharp structures with rigidity.   the detailed variation with rigidity of the flux spectral index is presented.   the spectral index is progressively hardening at high rigidities.   solar effects are also discussed.   protons are the most abundant particles in cosmic rays.   knowledge of the precise behavior of the proton flux as a function of energy is important in understanding the origin, acceleration, and propagation of cosmic rays.   the precise measurement of the proton flux in primary cosmic rays in the rigidity range from 1gv to 1.8tv performed by the alpha magnetic spectrometer ( ams ) during the first 30 months of operation onboard the international space station ( iss ) is described as published in  @xcite. moreover, the first 5 years of data collected from may 2011 to may 2016, reported in this proceeding, show structures, in the low rigidity range, related to the long and short time scale solar activity.
we study energy dissipation and heating by supersonic mhd turbulence in molecular clouds using athena, a new higher - order godunov code.   we analyze the dependence of the saturation amplitude, energy dissipation characteristics, power spectra, sonic scaling, and indicators of intermittency in the turbulence on factors such as the magnetic field strength, driving scale, energy injection rate, and numerical resolution. while convergence in the energies is reached at moderate resolutions, we find that the power spectra require much higher resolutions that are difficult to obtain. in a @xmath0 hydro run,   we find a power law relationship between the velocity dispersion and the spatial scale on which it is measured, while for an mhd run at the same resolution we find no such power law.   the time - variability and temperature intermittency in the turbulence both show a dependence on the driving scale, indicating that numerically driving turbulence by an arbitrary mechanism may not allow a realistic representation of these properties.   we also note similar features in the power spectrum of the compressive component of velocity for supersonic mhd turbulence as in the velocity spectrum of an initially - spherical mhd blast wave, implying that the power law form does not rule out shocks, rather than a turbulent cascade, playing a significant role in the regulation of energy transfer between spatial scales.
in a quantizing magnetic field, the two - dimensional electron ( 2deg ) gas has a rich phase diagram with broken translational symmetry phases such as wigner, bubble, and stripe crystals. in this paper, we derive a method to get the dynamical matrix of these crystals from a calculation of the density response function performed in the generalized random phase approximation ( grpa ).   we discuss the validity of our method by comparing the dynamical matrix calculated from the grpa  with that obtained from standard elasticity theory with the elastic coefficients obtained from a calculation of the deformation energy of the crystal.
we characterize the late - time scaling state of dry, coarsening, two - dimensional froths using a detailed, force - based vertex model.   we find that the slow evolution of bubbles leads to systematic deviations from @xmath0 angles at three - fold vertices in the froth, with an amplitude proportional to the vertex speed, @xmath1, but with a side - number dependence that is independent of time.   we also find that a significant number of @xmath2 side - switching processes occur for macroscopic bubbles in the scaling state, though most bubble annihilations involve four - sided bubbles at microscopic scales.
we investigate the relationship between the structure of a discrete graphical model and the support of the inverse of a generalized covariance matrix.   we show that for certain graph structures, the support of the inverse covariance matrix of indicator variables on the vertices of a graph reflects the conditional independence structure of the graph.   our work extends results that have previously been established only in the context of multivariate gaussian graphical models, thereby addressing an open question about the significance of the inverse covariance matrix of a non - gaussian distribution.   the proof exploits a combination of ideas from the geometry of exponential families, junction tree theory and convex analysis.   these population - level results have various consequences for graph selection methods, both known and novel, including a novel method for structure estimation for missing or corrupted observations.   we provide nonasymptotic guarantees for such methods and illustrate the sharpness of these predictions via simulations.
we determine the quark distributions and structure functions for both unpolarized and polarized dis of leptons on nucleons and nuclei.   the scalar and vector mean fields in the nucleus modify the motion of the quarks inside the nucleons. by taking into account this medium modification,   we are able to reproduce the experimental data on the unpolarized emc effect, and to make predictions for the polarized emc effect.   we discuss examples of nuclei where the polarized emc effect could be measured.   we finally present an extension of our model to describe fragmentation functions.
the out - of - equilibrium mean - field dynamics of a model for wave - particle interaction is investigated.   such a model can be regarded as a general formulation for all those applications where the complex interplay between particles and fields is known to be central, e.g., electrostatic instabilities in plasma physics, particle acceleration and free - electron lasers ( fels ).   the latter case is here assumed as a paradigmatic example. a transition separating different macroscopic regimes   is numerically identified and interpreted by making use of the so - called violent relaxation theory. in the context of free - electron lasers, such a theory is showed to be effective in predicting the saturated regime for energies below the transition.   the transition is explained as a dynamical switch between two metastable regimes, and is related to the properties of a stationary point of an entropic functional.
the galactic bulge region is a rich host of variable high - energy point sources.   these sources include bright and relatively faint x - ray transients, x - ray bursters, persistent neutron star and black - hole candidate binaries, x - ray pulsars, etc.. we have a program to monitor the galactic bulge region regularly and frequently with the @xmath0-ray observatory _ integral_. as a service to the scientific community the high - energy light curves of all the active sources as well as images of the region are made available through the www.   we show the first results of this exciting new program.   address = isoc, esac / esa, apartado 50727,   28080 madrid, spain     address = university of southampton, uk, altaddress = isdc, switzerland     address = dnsc, denmark     address = dnsc, denmark     address = isdc, switzerland     address = isas, japan     address = isoc, esac / esa, apartado 50727, 28080 madrid, spain     address = university of maryland, usa, altaddress = nasa / gsfc, usa     address = isdc, switzerland     address = esa - estec, the netherlands     address = esa - estec, the netherlands     address = inaf - iasf, italy     address = isoc, esac / esa, apartado 50727, 28080 madrid, spain     address = university of amsterdam, the netherlands
the aharonov  bohm effect is considered as a scattering event with nonrelativistic charged particles of the wavelength which is less than the transverse size of an impenetrable magnetic vortex.   the quasiclassical wkb method is shown to be efficient in solving this scattering problem.   we find that the scattering cross section consists of two terms, one describing the classical phenomenon of elastic reflection and another one describing the quantum phenomenon of diffraction ; the aharonov   bohm effect is manifested as a fringe shift in the diffraction pattern.   both the classical and the quantum phenomena are independent of the choice of a boundary condition at the vortex edge, providing that probability is conserved.   we show that a propagation of charged particles can be controlled by altering the flux of a magnetic vortex placed on their way.   @xmath0bogolyubov institute for theoretical physics, national academy of sciences, + 14-b metrologichna str.,   kyiv, 03680, ukraine + @xmath1physics department, taras shevchenko national university of kyiv, + 64 volodymyrska str.,   kyiv, 01601, ukraine    pacs : 03.65.ta, 75.70.kw, 41.85.-p, 03.65.nk    keywords : magnetic vortex, scattering ab effect, wkb method, diffraction, self - adjointness
we perform large - scale shell model monte carlo ( smmc ) calculations for many nuclei in the mass range @xmath0 in the complete @xmath1 model space using an effective quadrupole - quadrupole+pairing residual interaction.   our calculations are performed at finite temperatures between @xmath2 mev.   our main focus is the temperature dependence of the symmetry energy which we determine from the energy differences between various isobaric pairs with the same pairing structure and at different temperatures.   our smmc studies are consistent with an increase of the symmetry energy with temperature.   we also investigate possible consequences for core - collapse supernovae events.
recently the h.e.s.s. collaboration announced the detection of an unidentified gamma - ray source with an off - set from the galactic plane of 3.5 degrees : hess j1507 - 622. if the distance of the object is larger than about one kpc it would be physically located outside the galactic disk. the density profile of the ism perpendicular to the galactic plane, which acts as target material for hadronic gamma - ray production, drops quite fast with increasing distance   this fact places distance dependent constraints on the energetics and properties of off - plane gamma - ray sources like hess j1507 - 622 if a hadronic origin of the gamma - ray emission is assumed. for the case of this source   it is found that there seems to be no simple way to link this object to the remnant of a stellar explosions.   galactic gamma - ray sources, supernova remnants, compact binary merger remnants    = 0.5 cm
this work originates from a heart s images tracking which is to generate an apparent continuous motion, observable through intensity variation from one starting image to an ending one both supposed segmented.   given two images @xmath0 and @xmath1, we calculate an evolution process @xmath2 which transports @xmath0 to @xmath1 by using the optical flow. in this paper   we propose an algorithm based on a fixed point formulation and a space - time least squares formulation of the transport equation for computing a transport problem.   existence results are given for a transport problem with a minimum divergence for a dual norm or a weighted @xmath3-semi norm, for the velocity.   the proposed transport is compare with the transport introduced by dacorogna - moser.   the strategy is implemented in a 2d case and numerical results are presented with a first order lagrange finite element, showing the efficiency of the proposed strategy.    * keywords * ams classification 35f40 ; 35l85 ; 35r05 ;
we present results of general relativistic simulations of collapsing supermassive stars with and without rotation using the two - dimensional general relativistic numerical code nada, which solves the einstein equations written in the bssn formalism and the general relativistic hydrodynamics equations with high resolution shock capturing schemes.   these numerical simulations use an equation of state which includes effects of gas pressure, and in a tabulated form those associated with radiation and the electron - positron pairs.   we also take into account the effect of thermonuclear energy released by hydrogen and helium burning.   we find that objects with a mass of @xmath0 and an initial metallicity greater than @xmath1 do explode if non - rotating, while the threshold metallicity for an explosion is reduced to @xmath2 for objects uniformly rotating.   the critical initial metallicity for a thermonuclear explosion increases for stars with mass @xmath3. for those stars that do not explode we follow the evolution beyond the phase of black hole formation.   we compute the neutrino energy loss rates due to several processes that may be relevant during the gravitational collapse of these objects.   the peak luminosities of neutrinos and antineutrinos of all flavors for models collapsing to a bh are @xmath4  . the total radiated energy in neutrinos varies between @xmath5 ergs for models collapsing to a bh, and @xmath6 ergs for models exploding.
in this paper, we review the quantum mechanics of magnetic resonance imaging ( mri ).   we traverse its hierarchy of scales from the spin and orbital angular momentum of subatomic particles to the ensemble magnetization of tissue.   and we review a number of modalities used in the assessment of acute ischemic stroke and traumatic brain injury.   ( 1,0)300
we present a new study of deep star counts in the local group dwarf spheroidal ( dsph ) in ursa minor.   both the luminosity function ( lf ) and the colour - magnitude diagram ( cmd ) of the unevolved stars are compared with the lf and cmd of the old, metal - poor globular cluster m92.   the main sequence locations and turn - offs are identical within the errors.   since we know from the brighter evolved stars that the metallicities for these two disparate systems are the same this implies that they also have equal ages.   a direct comparison of faint lfs is then equivalent to comparison of the low - mass stellar initial mass functions ( imf ).   we find that their lfs are identical within the mass - range covered ( @xmath0 ).   the ursa minor   dsph has one of the highest apparent m / l ratios known in the local group, and is an extremely low surface brightness external galaxy.   m92 is a typical high surface brightness globular cluster, with no apparent dark matter.   these results lead to the conclusion that the low - mass stellar imf in systems that formed at high redshift is independent of environment.   indeed, it is consistent with the low - mass imf in star - forming regions today.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
a change of solute dispersion regime with the flow velocity has been studied both at the macroscopic and pore scales in a transparent array of capillary channels using an optical technique allowing for simultaneous local and global concentration mappings.   two solutions of different polymer concentrations ( @xmath0 and @xmath1  ppm ) have been used at different pclet numbers. at the macroscopic scale,   the displacement front displays a diffusive spreading : for @xmath2, the dispersivity @xmath3 is constant with @xmath4 and increases with the polymer concentration ; for @xmath5, @xmath3 increases as @xmath6 and is similar for the two concentrations. at the local scale,   a time lag between the saturations of channels parallel and perpendicular to the mean flow has been observed and studied as a function of the flow rate.   these local measurements suggest that the change of dispersion regime is related to variations of the degree of mixing at the junctions. for @xmath7,   complete mixing leads to pure geometrical dispersion enhanced for shear thinning fluids ; for @xmath8 weaker mixing results in higher correlation lengths along flow paths parallel to the mean flow and in a combination of geometrical and taylor dispersion.
we report on a 30  ks observation of the high - mass x  ray binary pulsar performed by  on september 1998.   the wide band spectrum is well fit by both a cutoff power law, or a power law modified by a high energy cutoff, plus a fluorescence iron line at 6.5  kev.   the two models are statistically equivalent.   the inclusion of a cyclotron resonance feature at @xmath036  kev  corresponding to a magnetic field strength @xmath1  g, where @xmath2 is the gravitational redshift  improves significantly the @xmath3 for the cutoff model but only marginally for the power law plus high energy cutoff model.   the statistical significance of our data is not adequate to discriminate between the two models, and even the _ normalized crab ratio _ technique, successfully used to pinpoint cyclotron features in the spectra of other x  ray pulsars, is not conclusive in answering the question whether the feature is real or it is an artifact due to an improper modeling of the continuum used to fit the data.   oao1657415 # 1
we explore the advantages offered by twin light beams produced in parametric down - conversion for precision measurement.   the symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high - precision inference of any symmetry - breaking effect, e.g. fiber birefringence.   we show that the quantity of entanglement is not the key feature for such an instrument. in a lossless   setting, scaling of precision at the ultimate ` heisenberg'limit is possible with photon counting alone.   even as photon losses approach 100% the precision is shot - noise limited, and we identify the crossover point between quantum and classical precision as a function of detected flux.   the predicted hypersensitivity is demonstrated with a bayesian simulation.
we introduce weinberg s idea of asymptotic safety and pave the way towards an asymptotically safe chiral yukawa system with a @xmath0 symmetry in a leading - order derivative expansion using nonperturbative functional rg equations. as a toy model sharing important features with the standard model we explicitely discuss @xmath1 for which we find a non - gauian fixed point and compute its critical exponents.   we observe a reduced hierarchy problem as well as predictions for the toy higgs and the toy top mass.
in this article we present a concrete proposal for spin squeezing the ultracold ground state polar paramagnetic molecule oh, a system currently under fine control in the laboratory. in contrast to existing work, we consider a single, non - interacting molecule with angular momentum greater than @xmath0. starting from an experimentally relevant effective hamiltonian  , we identify a parameter regime where different combinations of static electric and magnetic fields can be used to realize the single - axis twisting hamiltonian of kitagawa and ueda [ m. kitagawa and m. ueda, phys.   rev.   a * 47 *, 5138 ( 1993 ) ], the uniform field hamiltonian proposed by law et al.   [ c. k. law, h. t ng and p. t. leung, phys.   rev.   a * 63 *, 055601 ( 2001 ) ], and a model of field propagation in a kerr medium considered by agarwal and puri [ g. s. agarwal and r. r. puri, phys.   rev.   a * 39 *, 2969 ( 1989 ) ]. to support our conclusions,   we provide analytical expressions as well as numerical calculations, including optimization of field strengths and accounting for the effects of field misalignment.   our results have consequences for applications such as precision spectroscopy, techniques such as magnetometry, and stereochemical effects such as the orientation - to - alignment transition.
we present the design and construction of a squid - based magnetometer for operation down to temperatures @xmath0 mk, while retaining the compatibility with the sample holders typically used in commercial squid magnetometers. the system is based on a _   dc_-squid coupled to a second - order gradiometer.   the sample is placed inside the plastic mixing chamber of a dilution refrigerator and is thermalized directly by the @xmath1he flow.   the movement though the pickup coils is obtained by lifting the whole dilution refrigerator insert.   a home - developed software provides full automation and an easy user interface.
we present ccd photometric distance estimates of 100 scr ( supercosmos recons ) systems with @xmath0 @xmath1 0@xmath218/yr, 28 of which are new discoveries previously unpublished in this series of papers.   these distances are estimated using a combination of new @xmath3 photometry acquired at ctio and @xmath4 magnitudes extracted from 2mass.   the estimates are improvements over those determined using photographic plate @xmath5 magnitudes from supercosmos plus @xmath4, as presented in the original discovery papers. in total, 77 of the 100 systems investigated   are predicted to be within 25 pc.   if all 77 systems are confirmed to have @xmath6@xmath7 @xmath8 40 milliarcseconds, this sample would represent a 23% increase in m dwarf systems nearer than 25 pc in the southern sky.
we have developed a new hartree - fock - bogoliubov ( hfb ) code which has been specifically designed to study ground state properties of nuclei near the neutron and proton drip lines.   the unique feature of our code is that it takes into account the strong coupling to high - energy continuum states, up to an equivalent single - particle energy of 60 mev.   we solve the hfb equations for deformed, axially symmetric even - even nuclei in coordinate space on a 2-d lattice with basis - spline methods. for the p - h channel, the skyrme ( sly4 ) effective   n - n interaction is utilized, and for the p - p and h - h channel we use a delta interaction.   we present results for binding energies, deformations, normal densities and pairing densities, fermi levels, and pairing gaps.   in particular, we will discuss neutron - rich isotopes of oxygen ( @xmath0 ) and tin ( @xmath1 ).   = 10000 = 10000 = 10000
we wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. for long distance transmission,   the signal carrying these messages must be necessarily low frequency, typically 2 ghz, to which the plasma sheath is opaque.   the idea is to use the plasma properties to make the plasma sheath appear transparent.
in this letter we investigate the role of regular ( curvature singularity - free ) black holes in the framework of uv self - complete quantum gravity.   the existence of a minimal length, shielding the trans - planckian regime to any physical probe, is self - consistently included into the black hole probe itself. in this way we obtain to slightly shift the barrier below the planck length, with the uv self - complete scenario   self - consistently confirmed.
we present a new numerical code, pluto, for the solution of hypersonic flows in 1, 2 and 3 spatial dimensions and different systems of coordinates.   the code provides a multi - physics, multi - algorithm modular environment particularly oriented towards the treatment of astrophysical flows in presence of discontinuities.   different hydrodynamic modules and algorithms may be independently selected to properly describe newtonian, relativistic, mhd or relativistic mhd fluids.   the modular structure exploits a general framework for integrating a system of conservation laws, built on modern godunov - type shock - capturing schemes.   although a plethora of numerical methods has been successfully developed over the past two decades, the vast majority shares a common discretization recipe, involving three general steps : a piecewise polynomial reconstruction followed by the solution of riemann problems at zone interfaces and a final evolution stage.   we have checked and validated the code against several benchmarks available in literature.   test problems in 1, 2 and 3 dimensions are discussed.
we present a numerical method to compute the optimal maintenance time for a complex dynamic system applied to an example of maintenance of a metallic structure subject to corrosion.   an arbitrarily early intervention may be uselessly costly, but a late one may lead to a partial / complete failure of the system, which has to be avoided.   one must therefore find a balance between these too simple maintenance policies. to achieve this aim,   we model the system by a stochastic hybrid process.   the maintenance problem thus corresponds to an optimal stopping problem.   we propose a numerical method to solve the optimal stopping problem and optimize the maintenance time for this kind of processes.   dynamic reliability, predictive maintenance, piece - wise - deterministic markov processes, optimal stopping times, optimization of maintenance.
we present _ xmm - newton _ observations of the dusty wolf - rayet star wr  48a.   this is the first detection of this object in x - rays.   the _ xmm - newton _   epic spectra are heavily absorbed and the presence of numerous strong emission lines indicates a thermal origin of the wr  48a  x - ray emission, with dominant temperature components at kt@xmath0  kev and kt@xmath1  kev, the hotter component dominating the observed flux.   no significant x - ray variability was detected on time scales @xmath2  day.   although the distance to wr  48a  is uncertain, if it is physically associated with the open clusters danks 1 and 2 at d @xmath3   kpc, then the resultant x - ray luminosity l@xmath4 10@xmath5 ergs s@xmath6 makes it the most x - ray luminous wolf - rayet star in the galaxy detected so far, after the black - hole candidate cyg x-3.   we assume the following scenarios as the most likely explanation for the x - ray properties of wr 48a : ( 1 ) colliding stellar winds in a wide wr@xmath7o binary system, or in a hierarchical triple system with non - degenerate stellar components ; ( 2 ) accretion shocks from the wr 48a wind onto a close companion ( possibly a neutron star ).   more specific information about wr48a and its wind properties will be needed to distinguish between the above possibilities.
we present the first _ integral _ agn catalog, based on observations performed from launch of the mission in october 2002 until january 2004.   the catalog includes 42 agn, of which 10 are seyfert  1, 17 are seyfert  2, and 9 are intermediate seyfert  1.5.   the fraction of blazars is rather small with 5 detected objects, and only one galaxy cluster and no star - burst galaxies have been detected so far.   a complete subset consists of 32 agn with a significance limit of @xmath0 in the _   integral_/isgri 2040 kev data.   although the sample is not flux limited, the distribution of sources shows a ratio of obscured to unobscured agn of @xmath1, consistent with luminosity dependent unified models for agn.   only four compton - thick agn are found in the sample.   based on the _ integral _ data presented here, the seyfert  2 spectra are slightly harder ( @xmath2 ) than seyfert  1.5 ( @xmath3 ) and seyfert  1 ( @xmath4 ).
the edges high - band experiment aims to detect the sky - average brightness temperature of the @xmath0-cm signal from the epoch of reionization ( eor ) in the redshift range @xmath1. to probe this redshifted signal,   edges high - band conducts single - antenna measurements in the frequency range @xmath2 mhz from the murchison radio - astronomy observatory in western australia. in this paper, we describe the current strategy for calibration of the edges high - band receiver and report calibration results for the instrument used in the @xmath3 observational campaign.   we propagate uncertainties in the receiver calibration measurements to the antenna temperature using a monte carlo approach.   we define a performance objective of @xmath4  mk residual rms after modeling foreground subtraction from a fiducial temperature spectrum using a five - term polynomial.   most of the calibration uncertainties yield residuals of @xmath4  mk or less at @xmath5 confidence.   however, current uncertainties in the antenna and receiver reflection coefficients can lead to residuals of up to @xmath6 mk even in low - foreground sky regions.   these dominant residuals could be reduced by 1 ) improving the accuracy in reflection measurements, especially their phase 2 ) improving the impedance match at the antenna - receiver interface, and 3 ) decreasing the changes with frequency of the antenna reflection phase.
the technical merits of weak value amplification techniques are analyzed.   we consider models of several different types of technical noise in an optical context and show that weak value amplification techniques ( which only use a small fraction of the photons ) compare favorably with standard techniques ( which uses all of them ).   using the fisher information metric, we demonstrate that weak value techniques can put all of the fisher information about the detected parameter into a small portion of the events and show how this fact alone gives technical advantages.   we go on to consider a time correlated noise model, and find that a fisher information analysis indicates that while the standard method can have much larger information about the detected parameter than the postselected technique  . however, the estimator needed to gather the information is technically difficult to implement, showing that the inefficient ( but practical ) signal - to - noise estimation of the parameter is usually superior.   we also describe other technical advantages unique to imaginary weak value amplification techniques, focusing on beam deflection measurements. in this case, we discuss combined noise types ( such as detector transverse jitter, angular beam jitter before the interferometer and turbulence ) for which the interferometric weak value technique gives higher fisher information over conventional methods.   we go on to calculate the fisher information of the recently proposed photon recycling scheme for beam deflection measurements, and show it further boosts the fisher information by the inverse postselection probability relative to the standard measurement case.
we study initial cuts of models of weak two - sorted bounded arithmetics with respect to the strength of their theories and show that these theories are stronger than the original one.   more explicitly we will see that polylogarithmic cuts of models of @xmath0 are models of @xmath1 by formalizing a proof of nepomnjascij s theorem in such cuts.   this is a strengthening of a result by paris and wilkie.   we can then exploit our result in proof complexity to observe that frege proof systems can be sub exponentially simulated by bounded depth frege proof systems.   this result has recently been obtained by filmus, pitassi and santhanam in a direct proof. as an interesting observation   we also obtain an average case separation of resolution from @xmath2-frege by applying a recent result with tzameret.
we present the results from the first quasi - simultaneous multi - frequency ( 2.3, 5.0, 8.4 and 15 ghz ) very long baseline interferometry ( vlbi ) observations of a compact steep spectrum ( css ) superluminal source 3c138. for the first time, the spectral distribution of the components within its central 10 milli - arcsecond ( mas ) region was obtained.   this enables us to identify the component at the western end as the location of the nuclear activity on the assumption that the central engine is associated with one of the detected components.   the possibility that none of these visible components is the true core is also discussed.   the new measurements further clarify the superluminal motions of its inner jet components.   the multi - frequency data reveal a convex spectrum in one jet component, inferring the existence of free - free absorption by the ambient dense plasma.
the expansion dynamics of hot electron - positron - photon plasma droplets is dealt with within relativistic hydrodynamics.   such droplets, envisaged to be created in future experiments by irradiating thin foils with counter - propagating ultra - intense laser beams, are sources of flashes of gamma radiation.   warm electron - positron plasma droplets may be identified and characterized by a broadened 511 kev line.
we report the detection of 21-cm absorption at @xmath0 towards 1622 + 238 ( 3c336 ).   the line is very broad with a full - width half maximum ( fwhm ) of 235, giving a velocity integrated optical depth of @xmath1.   the centroid of the line is offset from that of the known damped lyman-@xmath2 absorption ( dla ) system by @xmath3, and _   if _ the lyman-@xmath2 and 21-cm absorption are due to the same gas, we derive a spin temperature of @xmath4 k, which would be the lowest yet in a dla. the wide profile, which is over four times wider than that of any other dla, supports the hypothesis that the hydrogen absorption is occurring either in the disk of a large underluminous spiral or a group of dim unidentified galaxies, associated with the single object which has been optically identified at this redshift.       quasars : absorption lines   cosmology : observations  cosmology : early universe  galaxies : ism  galaxies : individual ( 3c336 )
as an emerging field, ms - based proteomics still requires software tools for efficiently storing and accessing experimental data. in this work,   we focus on the management of lc - ms data, which are typically made available in standard xml - based portable formats.   the structures that are currently employed to manage these data can be highly inefficient, especially when dealing with high - throughput profile data.   lc - ms datasets are usually accessed through 2d range queries.   optimizing this type of operation could dramatically reduce the complexity of data analysis.   we propose a novel data structure for lc - ms datasets, called mzrtree, which embodies a scalable index based on the r - tree data structure.   mzrtree can be efficiently created from the xml - based data formats and it is suitable for handling very large datasets. we experimentally show that, on all range queries, mzrtree outperforms other known structures used for lc - ms data, even on those queries these structures are optimized for. besides, mzrtree is also more space efficient. as a result  , mzrtree reduces data analysis computational costs for very large profile datasets.   proteomic data formats, r - tree ; profile data, scalability, massive dataset
deep learning has recently led to great successes in tasks such as image recognition ( e.g *???   * )  . however, deep networks are still outmatched by the power and versatility of the brain, perhaps in part due to the richer neuronal computations available to cortical circuits.   the challenge is to identify which neuronal mechanisms are relevant, and to find suitable abstractions to model them. here  , we show how aspects of spike timing, long hypothesized to play a crucial role in cortical information processing, could be incorporated into deep networks to build richer, versatile representations.   we introduce a neural network formulation based on complex - valued neuronal units that is not only biologically meaningful but also amenable to a variety of deep learning frameworks. here  , units are attributed both a firing rate and a phase, the latter indicating properties of spike timing.   we show how this formulation qualitatively captures several aspects thought to be related to neuronal synchrony, including gating of information processing and dynamic binding of distributed object representations.   focusing on the latter, we demonstrate the potential of the approach in several simple experiments.   thus, neuronal synchrony could be a flexible mechanism that fulfills multiple functional roles in deep networks.   = 1
we propose four different mechanisms responsible for paramagnetic or diamagnetic persistent currents in normal metal rings and determine the circumstances for change of the current from paramagnetic to diamagnetic ones and _ vice versa_. it might qualitatively reproduce the experimental results of bluhm et al.   ( phys.   rev.   lett.   102, 136802 ( 2009 ) ).
we consider a multi - armed bandit problem in a setting where each arm produces a noisy reward realization which depends on an observable random _ covariate_. as opposed to the traditional _   static _ multi - armed bandit problem, this setting allows for dynamically changing rewards that better describe applications where side information is available.   we adopt a nonparametric model where the expected rewards are smooth functions of the covariate and where the hardness of the problem is captured by a _ margin _ parameter. to maximize the expected cumulative reward  , we introduce a policy called adaptively binned successive elimination ( abse ) that adaptively decomposes the global problem into suitably `` localized '' static bandit problems.   this policy constructs an adaptive partition using a variant of the successive elimination ( se ) policy.   our results include sharper regret bounds for the se policy in a static bandit problem and minimax optimal regret bounds for the abse policy in the dynamic problem.
phenix measurement of the fractional momentum loss ( ) of high identified hadrons are presented.   the of high which are computed from 39gev au+au over to 2.76tev pb+pb are found to vary by a factor of six.   we plotted the against several global variables,, and, and found global features.   it was found that 200gev au+au points are merging into the central 2.76tev pb+pb points when plotting against.
clusters of galaxies are massive enough to be considered representative samples of the universe, and to retain all of the heavy elements synthesized in their constituent stars.   since most of these metals reside in hot plasma, x - ray spectroscopy of clusters provides a unique and fundamental tool for studying chemical evolution.   i review the current observational status of x - ray measurements of the chemical composition of the intracluster medium, and its interpretation in the context of the nature and history of star and galaxy formation processes in the universe.   i provide brief historical and cosmological contexts, an overview of results from the mature _ asca _ observatory database, and new results from the _ chandra _ and _ xmm - newton _ x - ray observatories.   i conclude with a summary of important points and promising future directions in this rapidly growing field.       a&a
the @xmath0b solar neutrino flux inferred from a global analysis of solar neutrino experiments is within @xmath1% ( @xmath2 ) of the predicted standard solar model value if only active neutrinos exist, but could be as large as @xmath3 times the standard prediction if sterile neutrinos exist. we show that the total @xmath0b neutrino flux ( active plus sterile neutrinos ) can be determined experimentally to about @xmath4% ( @xmath2 ) by combining charged current measurements made with the kamland reactor experiment and with the sno cc solar neutrino experiment, provided the lma neutrino oscillation solution is correct and the simulated performance of kamland is valid. including also sno nc data, the sterile component of the @xmath0b neutrino flux can be measured by this method to an accuracy of about @xmath5% ( @xmath2 ) of the standard solar model flux.   combining super - kamiokande and kamland measurements and assuming the oscillations occur only among active neutrinos, the @xmath0b neutrino flux can be measured to @xmath6% ( @xmath2 ) ; the total flux can be measured to an accuracy of about @xmath7%.   the total @xmath8be solar neutrino flux can be determined to an accuracy of about @xmath9% ( @xmath2 ) by combining measurements made with the kamland, sno, and gallium neutrino experiments.   one can determine the total @xmath8be neutrino flux to a @xmath2 accuracy of about @xmath1% or better by comparing data from the kamland experiment and the borexino solar neutrino experiment provided both detectors work as expected.   the @xmath
plasma with a temperature close to the chromospheric one is ejected in solar eruptions.   such plasma can occult some part of emission of compact sources in active regions as well as quiet solar areas.   absorption phenomena can be observed in the microwave range as the so - called `` negative bursts '' and also in the he  ii 304    line.   the paper considers three eruptive events associated with rather powerful flares.   parameters of absorbing material of an eruption are estimated from multi - frequency records of a `` negative burst '' in one event.   `` destruction '' of an eruptive filament and its dispersion like a cloud over a huge area observed as a giant depression of the 304    line emission has been revealed in a few events.   one such event out of three ones known to us is considered in this paper.   another event is a possibility.   pacs numbers : 96.60.qf    * solar flare - related eruptions followed by long - lasting occultation of the emission in the he  ii 304    line and in microwaves *    v.  v.  grechnev@xmath0, i.  v.  kuzmenko@xmath1, i.  m.  chertok@xmath2, a.  m.  uralov@xmath0    @xmath0institute of solar - terrestrial physics sb ras, irkutsk, email : grechnev@iszf.irk.ru + @xmath1ussuriysk astrophysical observatory, primorsky krai, ussuriysk, email : kuzmenko_irina@mail.ru + @xmath0pushkov institute of terrestrial magnetism, ionosphere and radio wave propagation ( izmiran ), troitsk
we have studied the behavior of the electronic energy spin - splitting of @xmath0 based double quantum wells ( narrow gap structures ) under in - plane magnetic and transverse electric fields.   we have developed an improved @xmath1 version of the transfer matrix approach that consider contributions from abrupt interfaces and external fields when tunneling through central barrier exists.   we have included the land @xmath2-factor dependence on the external applied field. also, we have calculated electron density of states and photoluminescence excitation.   variations of the electron spin - splitting energy lead to marked peculiarities in the density of states. because the density of states is directly related to photoluminescence excitation,   these peculiarities are observable by this technique.
we present an analysis of the star formation history ( sfh ) of a field near the half light radius in the local group dwarf irregular galaxy ic  1613 based on deep _ hubble space telescope _ advanced camera for surveys imaging.   our observations reach the oldest main sequence turn - off, allowing a time resolution at the oldest ages of @xmath0 gyr.   our analysis shows that the sfh of the observed field in ic  1613 is consistent with being constant over the entire lifetime of the galaxy.   these observations rule out an early dominant episode of star formation in ic  1613.   we compare the sfh of ic  1613 with expectations from cosmological models.   since most of the mass is in place at early times for low mass halos, a naive expectation is that most of the star formation should have taken place at early times.   models in which star formation follows mass accretion result in too many stars formed early and gas mass fractions which are too low today ( the `` over - cooling problem '' ).   the depth of the present photometry of ic  1613 shows that, at a resolution of @xmath0 gyr, the star formation rate is consistent with being constant, at even the earliest times, which is difficult to achieve in models where star formation follows mass assembly.
we study the phase diagram of the spin - orbital model in both the weak and strong limits of the quartic spin - orbital exchange interaction.   this allows us to study quantum phase transitions in the model and to approach from both sides the most interesting intermediate - coupling regime and in particular the @xmath0-symmetric point of the hamiltonian.   it was suggested earlier by li _   et al _ [ phys.   rev.   lett. * 81 *, 3527 ( 1999 ) ] that at this point the ground state of the system is a plaquette spin - orbital liquid.   we argue that the state is more complex.   there is plaquette order, but it is anisotropic : bonds in one direction are stronger than those in the perpendicular direction.   this order is somewhat similar to that found recently in the frustrated @xmath1 heisenberg spin model.
this writeup is an introduction to some of the experimental issues involved in performing electroweak and @xmath0 physics measurements at the fermilab tevatron. in the electroweak sector  , we discuss @xmath1 and @xmath2 boson cross section measurements as well as the measurement of the mass of the @xmath1 boson. for @xmath0 physics,   we discuss measurements of @xmath3 mixing and @xmath4 violation.   this paper is geared towards nonexperts who are interested in understanding some of the issues and motivations for these measurements and how the measurements are carried out.   fermilab - conf-00 - 347-e +
we study the steady state of diffusion - limited coalescence, @xmath0, in the presence of a trap and with a background drift. in one dimension   this model can be analyzed exactly through the method of inter - particle distribution functions ( ipdf ). because of the irreversible trap the steady state of the system is a non - equilibrium state.   an interesting phase transition, controlled by the drift away from the trap, takes place : from a non - trivial steady state, when the drift is weak, to a trivial steady state ( the vacuum ), as the drift increases beyond some critical point.   surprisingly, regardless of the drift strength, the computed ipdf resembles that of an homogeneous _ equilibrium _ system, without the trap.   we suggest that this is due to  shielding " : the particle nearest to the trap shields the remaining particles from the effects of the trap.   finally, we compare the exact solution to that of a reaction - diffusion equation, and we determine the optimal values of the appropriate rate coefficients.    2
the finding that massive galaxies grow with cosmic time fired the starting gun for the search of objects which could have survived up to the present day without suffering substantial changes ( neither in their structures, neither in their stellar populations ).    nevertheless, and despite the community efforts, up to now only one firm candidate to be considered one of these relics is known : ngc  1277.   curiously, this galaxy is located at the centre of one of the most rich near galaxy clusters : perseus.   is its location a matter of chance?   should relic hunters focus their search on galaxy clusters?    in order to reply this question, we have performed a simultaneous and analogous analysis using simulations ( millennium i - wmap7 ) and observations ( new york university value - added galaxy catalogue ).   our results in both frameworks agree : it is more probable to find relics in high density environments.
we consider the anisotropic effect in the quantum hall systems by applying a confining potential that is not of parabolic type.   this can be done by extending susskind   polychronakos s approach to involve the matrices of two coupled harmonic oscillators.   starting from its action, we employ a unitary transformation to diagonalize the model.   the operators for building up the anisotropic ground state and creating the collective excitations can be constructed explicitly.   evaluating the area of the quantum hall droplet, we obtain the corresponding filling factor which is found to depend on the anisotropy parameter and to vary with the magnetic field strength.   this can be used to obtain the observed anisotropic filling factors, i.e. @xmath0, @xmath1 and others.   hep - th/0309085    * anisotropic quantum hall matrix model *   , * rudolf a. rmer@xmath2 * and * michael schreiber@xmath3 * + @xmath3_institut fr physik, technische universitt, + d-09107 chemnitz, germany   _   + @xmath2 _ department of physics, university of warwick, + coventry cv4 7al, uk _
this paper concerns stochastic perturbations of piecewise - smooth ode systems relevant for vibro - impacting dynamics, where impact events constitute the primary source of randomness.   such systems are characterised by the existence of switching manifolds that divide the phase space into regions where the system is smooth.   the initiation of impacts is captured by a grazing bifurcation, at which a periodic orbit describing motion without impacts develops a tangential intersection with a switching manifold.   oscillatory dynamics near regular grazing bifurcations are described by piecewise - smooth maps involving a square - root singularity, known as nordmark maps.   we consider three scenarios where coloured noise only affects impacting dynamics, and derive three two - dimensional stochastic nordmark maps with the noise appearing in different nonlinear or multiplicative ways, depending on the source of the noise.   consequently the stochastic dynamics differs between the three noise sources, and is fundamentally different to that of a nordmark map with additive noise.   this critical dependence on the nature of the noise is illustrated with a prototypical one - degree - of - freedom impact oscillator.
we consider the complexity of problems related to the combinatorial game free - flood - it, in which players aim to make a coloured graph monochromatic with the minimum possible number of flooding operations.   our main result is that computing the length of an optimal sequence is fixed parameter tractable ( with the number of colours as a parameter ) when restricted to rectangular @xmath0 boards.   we also show that, when the number of colours is unbounded, the problem remains np - hard on such boards.   these results resolve a question of clifford, jalsenius, montanaro and sach.
in quantum reading, a quantum state of light ( transmitter ) is applied to read classical information. in the presence of noise or for sufficiently weak signals  , quantum reading can outperform classical reading by enhanced state distinguishability. here   we show that the enhanced quantum efficiency depends on the presence in the transmitter of a particular type of quantum correlations, the discord of response.   different encodings and transmitters give rise to different levels of efficiency.   considering noisy quantum probes we show that squeezed thermal transmitters with non - symmetrically distributed noise among the field modes yield a higher quantum efficiency compared to coherent thermal quantum states.   the noise - enhanced quantum advantage is a consequence of the discord of response being a non - decreasing function of increasing thermal noise under constant squeezing, a behavior that leads to an increased state distinguishability.   we finally show that, for non - symmetric squeezed thermal states, the probability of error, as measured by the quantum chernoff bound, vanishes asymptotically with increasing _ local _ thermal noise at finite _ global _ squeezing.   therefore, at _ fixed _ finite squeezing, noisy but strongly discordant quantum states with large noise imbalance between the field modes can outperform noisy classical resources as well as pure entangled transmitters with the same finite level of squeezing.
i discuss the dynamical interaction of galactic disks with the surrounding dark matter halos. in particular it is demonstrated that if the self  gravitating shearing sheet, a model of a patch of a galactic disk, is embedded in a live dark halo, this has a strong effect on the dynamics of density waves in the sheet.   i describe how the density waves and the halo interact via halo particles either on orbits in resonance with the wave or on non - resonant orbits.   contrary to expectation the presence of the halo leads to a very considerable enhancement of the amplitudes of the density waves in the shearing sheet.   this effect appears to be the equivalent of the recently reported enhanced growth of bars in numerically simulated stellar disks embedded in live dark halos.   finally i discuss the counterparts of the perturbations of the disk in the dark halo.
we present a primary transit observation for the ultra hot ( @xmath0k ) gas giant expolanet wasp-121b, made using the _ hubble space telescope _ wide field camera 3 in spectroscopic mode across the 1.121.64@xmath1 wavelength range.   the 1.4@xmath1 water absorption band is detected at high confidence ( @xmath2 ) in the planetary atmosphere.   we also reanalyze ground - based photometric lightcurves taken in the @xmath3, @xmath4, and @xmath5 filters.   significantly deeper transits are measured in these optical bandpasses relative to the near - infrared wavelengths.   we conclude that scattering by high - altitude haze alone is unlikely to account for this difference, and instead interpret it as evidence for titanium oxide and vanadium oxide absorption.   enhanced opacity is also inferred across the @xmath6@xmath7 wavelength range, possibly due to iron hydride absorption.   if confirmed, wasp-121b will be the first exoplanet with titanium oxide, vanadium oxide, and iron hydride detected in transmission.   the latter are important species in m / l dwarfs, and their presence is likely to have a significant effect on the overall physics and chemistry of the atmosphere, including the production of a strong thermal inversion.
a class of states of the electromagnetic field involving superpositions of all the excited states above a specified low energy eigenstate of the electromagnetic field is introduced. these states and the photon - added coherent states   are shown to be the limiting cases of a generalized photon - added coherent states.   this new class of states is nonclassical, non - gaussian and has equal uncertainties in the field quadratures. for suitable choices of parameters,   these uncertainties are very close to those of the coherent states. nevertheless, these states exhibit sub - poissonian photon number distribution, which is a nonclassical feature. under suitable approximations,   these states become the generalized bernoulli states of the field.   nonclassicality of these states is quantified using their entanglement potential.   pacs : 42.50.   -p, 42.50.lc, 03.67.bg + keywords : truncated coherent states, photon - added coherent states, inverse boson operators, entanglement potential
we calculate the differential drell - yan production cross section in proton - nucleus collisions by including both next - to - leading order perturbative effects and effects of the nuclear medium.   we demonstrate that dilepton production in fixed target experiments is an excellent tool to study initial - state parton energy loss in large nuclei and to accurately determine the stopping power of cold nuclear matter.   we provide theoretical predictions for the attenuation of the drell - yan cross section at large values of feynman @xmath0 and show that for low proton beam energies experimental measurements at fermilab s e906 can clearly distinguish between nuclear shadowing and energy loss effects. if confirmed by data, our results may help determine the quark radiation length in cold nuclear matter @xmath1  m.
the key algorithms and features of the gasoline code for parallel hydrodynamics with self - gravity are described.   gasoline is an extension of the efficient pkdgrav parallel @xmath0-body code using smoothed particle hydrodynamics.   accuracy measurements, performance analysis and tests of the code are presented.   recent successful gasoline applications are summarized.   these cover a diverse set of areas in astrophysics including galaxy clusters, galaxy formation and gas - giant planets.   future directions for gasdynamical simulations in astrophysics and code development strategies for tackling cutting edge problems are discussed.   hydrodynamics, methods : numerical, methods : n - body simulations, dark matter 02.60.cb, 95.30.lz, 95.35.+d
hadron - hadron collisions at high energies are investigated in the ultra - relativistic - quantum - molecular - dynamics approach.   this microscopic transport model describes the phenomenology of hadronic interactions at low and intermediate energies ( @xmath0  gev ) in terms of interactions between known hadrons and their resonances. at higher energies, @xmath1  gev  , the excitation of color strings and their subsequent fragmentation into hadrons dominates the multiple production of particles in the urqmd model.   the model shows a fair overall agreement with a large body of experimental h - h data over a wide range of h - h center - of - mass energies.   hadronic reaction data with higher precision would be useful to support the use of the urqmd model for relativistic heavy ion collisions.   pacs : 24.10.lx, 13.75.-n, 13.85.-t    # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )
we measure the spectrum of cosmic rays with energies greater than @xmath0 ev with the fluorescence detectors ( fds ) and the surface detectors ( sds ) of the telescope array experiment using the data taken in our first 2.3-year observation from may 27 2008 to september 7 2010. a hybrid air shower reconstruction technique is employed to improve accuracies in determination of arrival directions and primary energies of cosmic rays using both fd and sd data.   the energy spectrum presented here is in agreement with our previously published spectra and the hires results.   ultra - high energy cosmic rays, telescope array, hybrid spectrum
energy transfer within photosynthetic systems can display quantum effects such as delocalized excitonic transport. recently, direct evidence of long - lived coherence has been experimentally demonstrated for the dynamics of the fenna - matthews - olson ( fmo ) protein complex [ engel _ et al. _,   nature 446, 782 ( 2007 ) ].   however, the relevance of quantum dynamical processes to the exciton transfer efficiency is to a large extent unknown. here  , we develop a theoretical framework for studying the role of quantum interference effects in energy transfer dynamics of molecular arrays interacting with a thermal bath within the lindblad formalism. to this end  , we generalize continuous - time quantum walks to non - unitary and temperature - dependent dynamics in liouville space derived from a microscopic hamiltonian.   different physical effects of coherence and decoherence processes are explored via a universal measure for the energy transfer efficiency and its susceptibility. in particular, we demonstrate that for the fmo complex an effective interplay between free hamiltonian and thermal fluctuations in the environment leads to a substantial increase in energy transfer efficiency from about 70% to 99%.
we develop a systematic framework for exclusive rare @xmath0 decays of the type @xmath1 at large dilepton invariant mass @xmath2.   it is based on an operator product expansion ( ope ) for the required matrix elements of the nonleptonic weak hamiltonian in this kinematic regime.   our treatment differs from previous work by a simplified operator basis, the explicit calculation of matrix elements of subleading operators, and by a quantitative estimate of duality violation.   the latter point is discussed in detail, including the connection with the existence of an ope and an illustration within a simple toy model.   cern - ph - th/2010 - 305 + lmu - asc  107/10 + tum - hep-788/10 + ippp/11/02 + dcpt/11/04 + january 2011    * theory of @xmath1 decays at high @xmath2 : + ope and quark - hadron duality *    m. beylich@xmath3, g. buchalla@xmath4 and th.   feldmann@xmath5    @xmath6cern, theory division, ch1211 geneva 23, switzerland + @xmath3ludwig - maximilians - universitt mnchen, fakultt fr physik, + arnold sommerfeld center for theoretical physics, d80333 mnchen, germany + @xmath5physik department, technische universitt mnchen, + james - franck - strae, d85748 garching, germany    pacs : 12.15.mm ; 12.39.st ; 13.20.he
the cooling of baryons in the centers of dark matter halos leads to a more concentrated dark matter distribution.   this effect has traditionally been calculated using the model of adiabatic contraction, which assumes spherical symmetry, while in hierarchical formation scenarios halos grow via multiple violent mergers.   we test the adiabatic contraction model in high - resolution cosmological simulations and find that the dissipation of gas indeed increases the density of dark matter and steepens its radial profile compared to the case without cooling. although the standard model systematically overpredicts the increase of dark matter density, a simple modification of the assumed invariant from @xmath0 to @xmath1, where @xmath2 is the orbit - averaged particle position, reproduces the simulated profiles within 10%.
we present results of a high - resolution imaging survey of barred s0sa galaxies which demonstrate that the central regions of these galaxies are surprisingly complex.   we see many inner bars  small, secondary bars ( typically less than a kiloparsec in radius ) located inside of, and probably rotating faster than, the large primary bars.   these are present in about one quarter to one third of all our sample.   in contrast to some theoretical expectations, they do _ not _ seem to enhance agn activity significantly.   a third of barred s0 s appear to host kiloparsec - scale _ disks _ within their bars ; but the frequency of such inner disks is much lower in our s0/a and sa galaxies.   in addition, we find one example of a _ triple _ barred galaxy, and two cases of purely _ stellar _ nuclear rings  probably the fossil remnants of past circumnuclear starbursts.   we comment briefly on results from an ongoing analysis of known double - barred systems, extending to hubble types as late as sbc, and discuss their characteristic sizes and orientations.
recent progress in the theoretical description of inclusive heavy flavour decays is reviewed. after an outline of the theoretical methods applications to total decay rates and semileptonic   decay spectra are presented.   @sh#2 fmsl@sh fmsl@sh fmsl@sh fmsl@sh#1#2#3@th    -3 cm    * ttp 9506 * + hep - ph/9503272    * inclusive decays + of heavy flavours *    thomas mannel + _ institut fr theoretische teilchenphysik, university of karlsruhe + kaiserstr.   12, d   76128 karlsruhe, germany.   _    _ contribution to the workshop on `` heavy quark physics '', + december 13  16, 1994, bad honnef, germany.   _    * ttp 9506 * + march 1995
we extend the abrams  strogatz model for competition between two languages  to the case of @xmath0 competing states ( i.e., languages ).   although the abrams  strogatz model for @xmath1 can be interpreted as modeling either majority preference or minority aversion, the two mechanisms are distinct when @xmath2.   we find that the condition for the coexistence of different states is independent of @xmath3 under the pure majority preference, whereas it depends on @xmath3 under the pure minority aversion.   we also show that the stable coexistence equilibrium and stable monopoly equilibria can be multistable under the minority aversion and not under the majority preference.   furthermore, we obtain the phase diagram of the model when the effects of the majority preference and minority aversion are mixed, under the condition that different states have the same attractiveness.   we show that the multistability is a generic property of the model facilitated by large @xmath3.
model - predicted and observed properties of the brightness distribution on m - type mira disks are discussed.   fundamental issues of limb - darkening and diameter definition, of assigning observational data to diameter - type quantities and of interpreting such quantities in terms of model diameters are outlined.   the influence of model properties upon interpretation of measured data is clarified.   the dependence of the centre - to - limb variation ( clv ) of intensity on wavelength, on stellar parameters and on variablity phase and cycle may be used for analyzing the geometrical and physical structure of the mira atmosphere, for determining fundamental stellar parameters, and for investigating the quality of models.   desirable future observations include simultaneous observations in different spectral features at different phases and cycles, observation of the position of the shock front and observation of the time- and wavelength - dependence of deviations from spherical symmetry.   * the article appeared in spie conf.   4838 ( 2003 ), p.163.   this version contains a reference update including additional references no.   31 and 70.
a trace gas sensor, based on quartz - enhanced photoacoustic spectroscopy ( qepas ), consisting of two acoustically coupled micro - resonators ( mr ) with an off - axis 20 khz quartz tuning fork ( qtf ) is demonstrated.   the complete acoustically coupled mr system is optimized based on finite element simulations and experimentally verified.   the qepas sensor is pumped resonantly by a nanosecond pulsed single - mode mid - infrared optical parametric oscillator ( mir opo ).   the sensor is used for spectroscopic measurements on methane in the 3.1 @xmath0 m to 3.5 @xmath0 m wavelength region with a resolution bandwidth of 1 @xmath1 and a detection limit of 0.8 ppm.   an allan deviation analysis shows that the detection limit at optimum integration time for the qepas sensor is 32 ppbv@190s and that the background noise is solely due to the thermal noise of the qtf.
for the first time an extensive search for various double beta decay modes of and has been performed.   a total exposure of 43.29 kg@xmath0days has been accumulated.   new half - life limits of into excited states of @xmath1te have been obtained ; the lower half - life limit for the first excited 2@xmath2 state at 602.7kev is @xmath3yrs ( 90 % cl ) and for the first excited 0@xmath2 state @xmath4yrs ( 90 % cl ). for the very first time, ground state and excited state transitions of have been experimentally explored. the obtained half - life limits for and into the first excited 2@xmath2 state of @xmath5cd are both @xmath6yrs ( 90 % cl ). a resonance enhancement in the decay rate for @xmath7 might be expected for the 0@xmath2-state at 1870.9kev due to degeneracy with the ground state.   no signal was found resulting in a lower half - life limit of @xmath8 yrs ( 90 % cl ) for this decay.   as all the excited state searches are based on gamma - lines, all half - life limits apply for both neutrino and neutrino - less modes.   neutrinoless ground state transitions were searched for in the and mode and a limit of @xmath9 yrs ( 90 % cl ) was obtained for decays of @xmath5sn, whilst the mode results are inconclusive.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    pacs : 13.15,13.20eb,14.60.pq,14.60.st    massive neutrinos, double beta decay
iac - pop is a code designed to solve the star formation history ( sfh ) of a complex stellar population system, like a galaxy, from the analysis of the color - magnitude diagram ( cmd ).   it uses a genetic algorithm to minimize a @xmath0 merit function comparing the star distributions in the observed cmd and the cmd of a synthetic stellar population.   a parametrization of the cmds is used, which is the main input of the code.   in fact, the code can be applied to any problem in which a similar parametrization of an experimental set of data and models can be made.   the method internal consistency and robustness against several error sources, including observational effects, data sampling and stellar evolution library differences, are tested.   it is found that the best stability of the solution and the best way to estimate errors is obtained by several runs of iac - pop with varying the input data parametrization.   the routine _ minniac _ is used to control this process.   iac - pop is offered for free use and can be downloaded from the site http://iac-star.iac.es/iac-pop.   the routine minniac is also offered under request, but support can not be provided for its use. the only requirement for the use of iac - pop and minniac is referencing this paper and crediting as indicated in the site.
we consider scalar - tensor theories of gravity in an accelerating universe.   the equations for the background evolution and the perturbations are given in full generality for any parametrization of the lagrangian, and we stress that apparent singularities are sometimes artifacts of a pathological choice of variables. adopting a phenomenological viewpoint, _ i.e. _, from the observations back to the theory, we show that the knowledge of the luminosity distance as a function of redshift up to @xmath0, which is expected in the near future, severely constrains the viable subclasses of scalar - tensor theories.   this is due to the requirement of positive energy for both the graviton and the scalar partner. assuming a particular form for the hubble diagram, consistent with present experimental data, we reconstruct the microscopic lagrangian for various scalar - tensor models, and find that the most natural ones are obtained if the universe is ( marginally ) closed.    epsf
the jila multidimensional optical nonlinear spectrometer ( jila - monstr ) is a robust, ultra - stable platform consisting nested and folded michelson interferometers that can be actively phase stabilized.   this platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delay between them, while maintaining phase stability.   the jila - monstr provides output pulses for nonlinear excitation of materials and phase - stabilized reference pulses for heterodyne detection of the induced signal.   this arrangement is ideal for performing coherent optical experiments, such as multidimensional fourier - transform spectroscopy, which records the phase of the nonlinear signal as a function of the time delay between several of the excitation pulses.   the resulting multidimensional spectrum is obtained from a fourier transform.   this spectrum can resolve, separate and isolate coherent contributions to the light - matter interactions associated with electronic excitation at optical frequencies. to show the versatility of the jila - monstr,   several demonstrations of two - dimensional fourier - transform spectroscopy are presented, including an example of a phase - cycling scheme that reduces noise.
we describe optical photometric and spectroscopic observations of the bright variable bg geminorum.   optical photometry shows a pronounced ellipsoidal variation of the k0 i secondary, with amplitudes of @xmath0 0.5 mag at vr@xmath1i@xmath1 and a period of 91.645 days.   a deep primary eclipse is visible for @xmath2 4400  ; a shallower secondary eclipse is present at longer wavelengths.   eclipse timings and the radial velocity curve of the k0 secondary star indicate an interacting binary where a lobe - filling secondary, @xmath3, transfers material into a extended disk around a massive primary, @xmath4.   the primary star is either an early b - type star or a black hole.   if it did contain a black hole, bg gem would be the longest period black hole binary known by a factor of 10, as well as the only eclipsing black hole binary system.   # 1    # 1    # 1 + = = = 1=1=0pt = 2=2=0pt
the merger of a binary of neutron stars provides natural explanations for many of the features of short gamma - ray bursts ( sgrbs ), such as the generation of a hot torus orbiting a rapidly rotating black hole, which can then build a magnetic jet and provide the energy reservoir to launch a relativistic outflow. yet  , this scenario has problems explaining the recently discovered long - term and sustained x - ray emission associated with the afterglows of a subclass of sgrbs.   we propose a new model that explains how an x - ray afterglow can be sustained by the product of the merger and how the x - ray emission is produced before the corresponding emission in the gamma - band, although it is observed to follow it.   overall, our paradigm combines in a novel manner a number of well - established features of the emission in sgrbs and results from simulations.   because it involves the propagation of an ultra - relativistic outflow and its interaction with a confining medium, the paradigm also highlights a unifying phenomenology between short and long grbs.
we report the discovery of diffuse hard ( 15 kev ) x - ray emission around jupiter in a deep 160 ks _ suzaku _ xis data.   the emission is distributed over @xmath0 jovian radius and spatially associated with the radiation belts and the io plasma torus.   it shows a flat power - law spectrum with a photon index of 1.4@xmath10.2 with the 15 kev x - ray luminosity of ( 3.3@xmath10.5)@xmath210@xmath3 erg s@xmath4.   we discussed its origin and concluded that it seems to be truly diffuse, although a possibility of multiple background point sources can not be completely rejected with a limited angular resolution.   if it is diffuse, the flat continuum indicates that x - rays arise by the non - thermal electrons in the radiation belts and/or the io plasma torus.   the synchrotron and bremsstrahlung models can be rejected from the necessary electron energy and x - ray spectral shape, respectively. the inverse - compton scattering off solar photons by ultra - relativistic ( several tens mev ) electrons   can explain the energy and the spectrum but the necessary electron density is @xmath510 times larger than the value estimated from the empirical model of jovian charge particles.
we report the suzaku observation of 1e  1740.7@xmath02942, a black hole candidate called the `` great annihilator '' ( ga ).   the high - quality spectrum of suzaku provides the severest constraints on the parameters of the ga.   two clumpy structures are found around the ga in the line images of fe k@xmath1 at 6.4  kev and s k@xmath1 at 2.45  kev.   one clump named m359.23@xmath00.04 exhibits the 6.4-kev line with an equivalent width of @xmath2 1.2  kev, and is associated with a molecular cloud in the radio cs(@xmath3=10 ) map.   thus the 6.4-kev line from m359.23@xmath00.04 is likely due to x - ray fluorescence irradiated by an external x - ray source.   the irradiating x - rays would be either the past flare of sagittariusa@xmath4 or the bright nearby source, the ga.   the other clump named g359.12@xmath00.05 is associated with the radio supernova remnant candidate g359.07@xmath00.02.   we therefore propose that g359.12@xmath00.05 is an x - ray counterpart of g359.07@xmath00.02.   g359.12@xmath00.05 has a thin thermal plasma spectrum with a temperature of @xmath5  kev.   the plasma parameters of g359.12@xmath00.05 are consistent with those of a single supernova remnant in the galactic center region.
the optical afterglow of grb 010222 was observed using the recently installed 2-m telescope at the indian astronomical observatory, hanle, and the telescopes at the vainu bappu observatory, kavalur, beginning @xmath0  day after the detection of the event.   the results based on these photometric observations combined with others reported in the literature are presented in this paper.   the @xmath1 band light curve shows an initial decline of intensities proportional to @xmath2 which steepens, after 10.3 hours, to @xmath3. following the model of collimated outflow,   the early break in the light curve implies a very narrow beam angle ( @xmath4 ).   the two decay rates are consistent with the standard jet model in a uniform density ambient medium, but require a hard spectrum of electron power density with @xmath5.   the @xmath1 band light between 14 and 17 hours since outburst departs from the power law fit by 0.1 mag and shows some evidence for fluctuations over timescales of an hour in the observer s frame.   such deviations are expected due to density inhomogeneities if the ambient medium is similar to the local interstellar medium.   grb 010222 is thus an example of a highly collimated outflow with a hard spectrum of electron energy distribution in normal interstellar environment.   = -2truecm = -2truecm
the probability - generating function of the number of electron - positron pairs produced in a uniform electric field is constructed.   the mean and variance of the numbers of pairs are calculated, and analytical expressions for the probability of low numbers of electron - positron pairs are given.   a recursive formula is derived for evaluating the probability of any number of pairs. in electric fields of supercritical strength @xmath0, where @xmath1 is the electron charge,   @xmath2 is the electric field, and @xmath3 is the electron mass, a branch - point singularity of the probability - generating function penetrates the unit circle @xmath4, which leads to the asymptotic divergence of the cumulative probability.   this divergence indicates a failure of the continuum limit approximation. in the continuum limit and for any field strength,   the positive definiteness of the probability is violated in the tail of the distribution.   analyticity, convergence, and positive definiteness are restored upon the summation over discrete levels of electrons in the normalization volume.   numerical examples illustrating the field strength dependence of the asymptotic behavior of the probability distribution are presented.
differential spectroscopy during exoplanet transits permits to reconstruct spectra of small stellar surface portions that successively become hidden behind the planet.   the center - to - limb behavior of stellar line shapes, asymmetries and wavelength shifts will enable detailed tests of 3-dimensional hydrodynamic models of stellar atmospheres, such that are required for any precise determination of abundances or seismic properties.   such models can now be computed for widely different stars but have been feasible to test in detail only for the sun with its resolved surface structure.   although very high quality spectra are required, already current data permit reconstructions of line profiles in the brightest transit host stars such as hd  209458 ( g0 v ).
giant lobes of plasma extend @xmath055  above and below the galactic center, glowing in emission from gamma rays ( the fermi bubbles ) to microwaves ( the wmap haze ) and polarized radio waves.   we use ultraviolet absorption - line spectra from the _ hubble space telescope _ to constrain the velocity of the outflowing gas within these regions, targeting the quasar pds456 ( @xmath1=10.4, + 11.2 ).   this sightline passes through a clear biconical structure seen in hard x - ray and gamma - ray emission near the base of the northern fermi bubble.   we report two high - velocity metal absorption components, at @xmath2=@xmath3235 and + 250kms@xmath4, which can not be explained by co - rotating gas in the galactic disk or halo.   their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the galactic center.   we develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of @xmath5900kms@xmath4  and a full opening angle of @xmath0110  ( matching the x - ray bicone ).   this indicates galactic center activity over the last @xmath02.54.0myr, in line with age estimates of the fermi bubbles.   the observations illustrate the use of uv spectroscopy to probe the properties of swept - up gas venting into the fermi bubbles.
the response to an electric field ( dc and ac ) of electronic systems in which the fermi `` surface '' consists of a number of 3d weyl points ( such as some pyrochlore iridates ) exhibits a peculiar combination of characteristics usually associated with insulating and conducting behaviour. generically a neutral plasma in clean materials can be described by a tight binding model with a strong spin - orbit interaction.   a system of that type has a vanishing dc conductivity ; however the current response to the dc field is very slow : the current decays with time in a powerwise manner, different from an insulator. the ac conductivity, in addition to a finite real part @xmath0 which is linear in frequency, exhibits an imaginary part @xmath1  that increases logarithmically as function of the uv cutoff ( atomic scale ).   this leads to substantial dielectric response like a large dielectric constant at low frequencies.   this is in contrast to a 2d weyl semimetal like graphene at neutrality point where the ac conductivity is purely pseudo - dissipative.   the coulomb interaction between electrons is long range and sufficiently strong to make a significant impact on transport.   the interaction contribution to the ac conductivity is calculated within the tight binding model.   the result for the real part expressed via the renormalized ( at frequency @xmath2 ) fermi velocity @xmath3 is : @xmath4 $ ].
while most of the microwave background fluctuations on angular scales greater than a few arcminutes were generated at @xmath0, the low redshift universe does distort the microwave background.   since the sloan digital sky survey ( sdss ) traces the structures in the low - redshift universe, we can gain additional insights into the physics of the low - redshift universe by cross - correlating microwave background maps with template maps produced from the sdss.   we present a formalism for cross - correlating data from the microwave anisotropy probe ( map ) with the sloan survey for the thermal sunyaev - zeldovich ( sz ) effect, the integrated sachs - wolfe ( isw ) effect, and weak lensing.   this formalism is used to compute the signal - to - noise for cross - correlating these effects with various classes of tracer objects from the sdss.   it is found that the anticipated samples of sdss quasars and galaxies with photometrically - determined redshifts would be good tracers for cross - correlating with the cmb.   we find that the sz - galaxy cross - correlation would give good constraints on pressure fluctuations in supercluster - scale gas.   cross - correlating weakly - lensed quasars with maps of the convergence of the cmb is found to give strong constraints on @xmath1 as well as the equation of state @xmath2.   we find that the isw cross - correlation gives poor signal - to - noise using these techniques.
the nature of electronic eigenstates and quantum transport in a comb - shaped fibonacci nanostructure model is investigated within a tight - binding framework.   periodic linear chains are side - attached to a fibonacci chain, giving it the shape of an aperiodic comb.   the effect of the side - attachments on the usual cantor set energy spectrum of a fibonacci chain is analyzed using the green s function technique. a special correlation between the coupling of the side - attached chain with the fibonacci chain and the inter - atomic coupling of the fibonacci chain results in a dramatic triggering of the fragmented cantor set energy spectrum into multiple sets of continuous sub - bands of extended eigenstates.   the result is valid even for a disordered comb and turns out to be a rare exception of the conventional anderson localization problem.   the electronic transport thus can be made selectively ballistic within desired energy regimes.   the number and the width of such continuous sub - bands can be easily controlled by tuning the number of atomic sites in the side - coupled periodic linear chains.   this gives us a scope of proposing such aperiodic nanostructures as potential candidates for prospective energy selective nanoscale filtering devices.
recent experiments on the s=1/2 antiferromagnetic chain compound, cu benzoate, discovered an unexpected gap scaling as approximately the 2/3 power of an applied magnetic field. a theory of this gap, based on an effective staggered field, orthogonal to the applied uniform field, resulting from a staggered gyromagnetic tensor and a dzyaloshinskii - moriya interaction, leading to a sine - gordon quantum field theory, has been developed.   here we discuss many aspects of this subject in considerable detail, including a review of the s=1/2 chain in a uniform field, a spin - wave theory analysis of the uniform plus staggered field problem, exact amplitudes for the scaling of gap, staggered susceptibility and staggered magnetization with field or temperature, intensities of soliton and breather peaks in the structure function and field and temperature dependence of the total susceptibility.
we study the efimov effect in a harmonic oscillator in the hyperspherical formulation, and show how a reduced model allows for a description that is a generalization of the efimov effect in free space and leads to results that are easily interpreted.   efimov physics may be observed by varying the value of the scattering length, since in the regime where the trimers have a mixed harmonic oscillator and efimov character, the inelastic properties of these states are still manageable.   the model also allows for the study of non - universal efimov trimers by including the effective range scattering parameter. while we find that in a certain regime the effective range parameter can take over the role of the three - body parameter, interestingly, we obtain a numerical relationship between these two parameters different from what was found in other models.
we present high spatial resolution spectroscopic observations of the proplyd 167 - 317 ( lv2 ) near the trapezium cluster in the orion nebula, obtained during the system verification run of the gemini multi object spectrograph ( gmos ) integral field unit ( ifu ) at the gemini south observatory.   we have detected 38 forbidden and permitted emission lines associated with the proplyd and its redshifted jet.   we have been able to detect three velocity components in the profiles of some of these lines : a peak with a 28 - 33 km s@xmath0 systemic velocity that is associated with the photoevaporated proplyd flow, a highly redshifted component associated with a previously reported jet ( which has receding velocities of about 80 - 120 km s@xmath0 with respect to the systemic velocity and is spatially distributed to the southeast of the proplyd ) and a less obvious, approaching structure, which may possibly be associated with a faint counter - jet with systemic velocity of @xmath1 km s@xmath0.   we find evidences that the redshifted jet has a variable velocity, with slow fluctuations as a function of the distance from the proplyd.   we present several background subtracted, spatially distributed emission line maps and we use this information to obtain the dynamical characteristics over the observed field. using a simple model and with the extinction corrected h@xmath2 fluxes, we estimate the mass loss rate for both the proplyd photoevaporated flow and the redshifted microjet, obtaining @xmath3 m@xmath4 year@xmath0 and @xmath5 m@xmath4 year@xmath0, respectively.
we propose a focus of attention mechanism to speed up the perceptron algorithm.   focus of attention speeds up the perceptron algorithm by lowering the number of features evaluated throughout training and prediction. whereas the traditional perceptron evaluates all the features of each example, the attentive perceptron evaluates less features for easy to classify examples, thereby achieving significant speedups and small losses in prediction accuracy.   focus of attention allows the attentive perceptron to stop the evaluation of features at any interim point and filter the example.   this creates an attentive filter which concentrates computation at examples that are hard to classify, and quickly filters examples that are easy to classify.
we report the detection of a non  thermal hard x  ray component from sco x1 based upon the analysis of 20220kev spectra obtained with the hexte experiment on - board the _ rxte _ satellite.   we find that the addition of a power  law component to a thermal bremsstrahlung model is required to achieve a good fit in 5 of 16 observations analyzed.   using pca data we were able to track the movement of the source along the z diagram, and we found that the presence of the hard x  ray tail is not confined to a specific z position.   however, we do observe an indication that the power law index hardens with increasing @xmath0, as indicated from the position on the z diagram.   we find that the derived non  thermal luminosities are @xmath110% of that derived for the brightest of the atoll sources.
we present a qcd - based model where rescattering between final state partons in deep inelastic scattering leads to events with large rapidity gaps and a leading proton. in the framework of this model the amplitude for multiple gluon exchanges is calculated in the eikonal approximation to all orders in perturbation theory. both large and small invariant mass @xmath0 limits are considered.   the model successfully describes the precise hera data on the diffractive deep inelastic cross section in the whole available kinematical range and gives new insight into the density of gluons at very small momentum fractions in the proton.
we propose to use a nomarski imaging interferometer to measure the out - of - plane displacement field of mems.   it is shown that the measured optical phase arises both from height and slope gradients. using four integrating buckets a more efficient approach to unwrap the measured phase is presented, thus making the method well suited for highly curved objects.   slope and height effects are then decoupled by expanding the displacement field on a functions basis, and the inverse transformation is applied to get a displacement field from a measure of the optical phase map change with a mechanical loading  . a measurement reproducibility of about 10 pm is achieved, and typical results are shown on a microcantilever under thermal actuation, thereby proving the ability of such a set - up to provide a reliable full - field kinematic measurement without surface modification.
we compare classes of finite relational structures via monadic second - order transductions.   more precisely, we study the preorder where we set @xmath0 if, and only if, there exists a transduction @xmath1 such that @xmath2.   if we only consider classes of _ incidence structures _ we can completely describe the resulting hierarchy.   it is linear of order type @xmath3.   each level can be characterised in terms of a suitable variant of tree - width.   canonical representatives of the various levels are0.08em : the class of all trees of height  @xmath4, for each @xmath5, of all paths, of all trees, and of all grids.
we study ising chains with arbitrary multispin finite - range couplings, providing an explicit solution of the associated inverse ising problem, i.e. the problem of inferring the values of the coupling constants from the correlation functions. as an application  , we reconstruct the couplings of chain ising hamiltonians having exponential or power - law two - spin plus three- or four - spin couplings.   the generalization of the method to ladders and to ising systems where a mean - field interaction is added to general finite - range couplings is as well as discussed.
the crossover from thermal hopping to quantum tunneling is studied.   we show that the decay rate @xmath0 with dissipation can accurately be determined near the crossover temperature. besides considering the wentzel - kramers - brillouin ( wkb ) exponent, we also calculate contribution of the fluctuation modes around the saddle point and give an extended account of a previous study of crossover region  . we deal with two dangerous fluctuation modes whose contribution ca nt be calculated by the steepest descent method and show that higher order couplings between the two dangerous modes need to be taken into considerations. at last the crossover from thermal hopping to quantum tunneling in the molecular magnet mn@xmath1ac is studied.   pacs number(s ) : 75.45.+j, 75.50.tt.
we present an analysis of a nested mach - zehnder interferometer in which an ensemble of identical pre- and postselected particles leave a weak trace.   a knowledge of the weak value partially destroys the quantum interference.   the results, contrary to some recent claims, are in accordance with the usual quantum mechanical expectations.
various phenomenological models of particle multiplicity distributions are discussed using a general form of a unified model which is based on the grand canonical partition function and feynman s path integral approach to statistical processes.   these models can be written as special cases of a more general distribution which has three control parameters which are @xmath0, @xmath1, @xmath2.   the relation to these parameters to various physical quantities are discussed.   a connection of the parameter @xmath0 with fisher s critical exponent @xmath3 is developed. using this grand canonical approach,   moments, cumulants and combinants are discussed and a physical interpretation of the combinants are given and their behavior connected to the critical exponent @xmath3.   various physical phenomena such as hierarchical structure, void scaling relations, kno scaling features, clan variables, and branching laws are shown in terms of this general approach.   several of these features which were previously developed in terms of the negative binomial distribution are found to be more general.   both hierarchical structure and void scaling relations depend on the fisher exponent @xmath3.   applications of our approach to the charged particle multiplicity distribution in jets of l3 and h1 data are given.   it is shown that just looking at the mean and fluctuation of data is not enough to distinguish these distributions or the underlying mechanism.   the mean, fluctuation and third cummulant of distribution determine three parameters @xmath1, @xmath2, @xmath0.   we find that a generalized random work model fits the data better than the widely used negative binomial model.
the evolution of the methods used to find solutions of einstein s field equations during the last 100 years is described.   early papers used assumptions on the coordinate forms of the metrics. since the 1950s more invariant methods have been deployed in most new papers.   the uses to which the solutions found have been put are discussed, and it is shown that they have played an important role in the development of many aspects, both mathematical and physical, of general relativity.   address = school of mathematical sciences, queen mary, university of london, mile end road, london e1 4ns, u.k. +   email : m.a.h.maccallum@qmul.ac.uk
we present near - infrared high resolution observations of the young binary system z  canis  majoris using the adaptive optics system at the keck - ii telescope.   both components are unresolved at 1.25@xmath0 m and 1.65@xmath0 m, although high dynamic range images reveal a previously unknown jet - like feature in the circumstellar environment.   we argue that this feature probably arises from light scattered off the walls of a jet - blown cavity, and proper motion studies of this feature can probe the dynamics of the bipolar outflow.   potentially, the morphology of the dust - laden cavity walls offers a new probe of the momentum profile and collimation of bipolar winds from young stellar objects.   we also derive high precision binary parameters, which when combined with historical data have allowed the first detection of orbital motion.   lastly, our observations confirm the high degree of flux variability in the system ; the north - west binary component is dominant at h - band, in contrast to all previous observations.
we analyze a recently proposed method to create fractional quantum hall ( fqh ) states of atoms confined in optical lattices [ a. srensen _   et al. _,   phys.   rev.   lett. * 94 * 086803 ( 2005 ) ]. extending the previous work, we investigate conditions under which the fqh effect can be achieved for bosons on a lattice with an effective magnetic field and finite onsite interaction.   furthermore, we characterize the ground state in such systems by calculating chern numbers which can provide direct signatures of topological order and explore regimes where the characterization in terms of wavefunction overlap fails.   we also discuss various issues which are relevant for the practical realization of such fqh states with ultra cold atoms in an optical lattice, including the presence of the long - range dipole interaction which can improve the energy gap and stabilize the ground state.   we also investigate a new detection technique based on bragg spectroscopy to probe these system in an experimental realization.
the galaxy cluster 1e0657 - 56 ( @xmath0 ) is remarkably well - suited for addressing outstanding issues in both galaxy evolution and fundamental physics.   we present a reconstruction of the mass distribution from both strong and weak gravitational lensing data.   multi - color, high - resolution hst acs images allow detection of many more arc candidates than were previously known, especially around the subcluster. using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. combining this information with shape measurements of `` weakly '' lensed sources  , we derive a high - resolution, absolutely - calibrated mass map, using no assumptions regarding the physical properties of the underlying cluster potential.   this map provides the best available quantification of the total mass of the central part of the cluster.   we also confirm the result from @xcite that the total mass does _ not _ trace the baryonic mass.   # 1#1 # 1 # 1 ( # 1 ) # 1#1 # 1#1 # 1#1
the numerical solution for the @xmath0 static soliton of the @xmath1 skyrme model shows a profile function dependence which is not exactly radial.   we propose to quantify this with the introduction of an axially symmetric oblate ansatz parametrized by a scale factor @xmath2 we then obtain a relatively deformed bound soliton configuration with @xmath3.   this is the first step towards to description of @xmath4 quantized states such as the deuteron with a non - rigid oblate ansatz where deformations due to centrifugal effects are expected to be more important.    ]
the electrical conduction properties of g4-dna are investigated using a hybrid approach, which combines electronic structure calculations, molecular dynamics ( md ) simulations and the formulation of an effective tight - binding model hamiltonian.   charge transport is studied by computing transmission functions along the md trajectories. though g4-dna is structurally more stable than dsdna  , our results strongly suggest that the potential improvement of the electrical transport properties in the former is not necessarily related to an increased stability, but rather to the fact that g4 is able to explore in its conformational space a larger number of charge - transfer active conformations.   this in turn is a result of the non - negligible inter - strand matrix elements, which allow for additional charge transport pathways.   the higher structural stability of g4 can however play an important role once the molecules are contacted by electrodes. in this case, g4 may experience weaker structural distortions than dsdna and thus preserve to a higher degree its conduction properties.
we have surveyed the optical linear polarimetric properties of 65 soft x - ray selected rosat active galactic nuclei ( agn ).   most of these sources show low polarization ( @xmath01% ) and no optical reddening.   this is in agreement with the x - ray results suggesting a direct view on the center.   however, two of our agn show polarization as high as 78% and high reddening.   this optical reddening suggests a high column of dusty gas, but why does this gas not absorb the soft x - rays?   we suggest that the dusty gas is actually ionized.   there is evidence for these warm absorbers from x - ray absorption features seen in rosat and asca spectra.
in this paper, we investigate gpu based parallel triangular solvers systematically.   the parallel triangular solvers are fundamental to incomplete lu factorization family preconditioners and algebraic multigrid solvers.   we develop a new matrix format suitable for gpu devices.   parallel lower triangular solvers and upper triangular solvers are developed for this new data structure. with these solvers, ilu preconditioners and domain decomposition preconditioners   are developed.   numerical results show that we can speed triangular solvers around seven times faster.   solver, gpu, parallel, linear system
when a quantum field theory is constructed on a curved background spacetime, the gravitationally induced vacuum polarization typically induces a non - zero vacuum expectation value for the quantum stress - energy tensor.   it is well - known that this gravitational vacuum polarization often violates the point - wise energy conditions and sometimes violates the averaged energy conditions. in this paper   i begin a systematic attack on the question of where and by how much the various energy conditions are violated. to keep the discussion manageable, i work in the test - field limit, and focus on conformally coupled massless scalar fields in schwarzschild spacetime, using the hartle  hawking vacuum.   the discussion invokes a mixture of analytical and numerical techniques, and critically compares the qualitative behaviour to be expected from the page approximation with that adduced from the numerical calculations of anderson, hiscock, and samuel.   i show that the various point - wise energy conditions are violated in a series of onion - like layers located between the unstable photon orbit and the event horizon, the sequence of violations being dec, wec, and ( nec+sec ).   furthermore the anec is violated for _ some _ of the null geodesics trapped in this region.   having established the basic machinery in this paper, the boulware vacuum will be treated in a companion paper, while studies of the unruh vacuum should be straightforward, as should extensions to non - conformal couplings, massive scalars, and reissner  nordstrm geometries.
we report a large enhancement of 1.7 in deuteron polarization up to values of @xmath0 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization.   this target was used during a deep inelastic polarized muon - deuteron scattering experiment at cern.   measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings.   although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.   # 1
in high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. in this paper   we present a technique to reject heavy charged particle contamination in the 100 gev electron beam of the h4 beam line at cern sps.   the method is based on the detection with bgo scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet.   a 100 gev @xmath0 beam is used to test the method in the na64 experiment resulting in a suppression factor of @xmath1 while the efficiency for electron detection is @xmath295%.   the spectra and the rejection factors are in very good agreement with the monte carlo simulation.   the reported suppression factors are significantly better than previously achieved.    0.25 cm
this is mainly a survey article on the recent development of the theory of graph - like legendrian unfoldings and its applications.   the notion of big legendrian submanifolds was introduced by zakalyukin for describing the wave front propagations.   graph - like legendrian unfoldings belong to a special class of big legendrian submanifolds.   although this is a survey article, some new original results and the corrected proofs of some results are given.   to the memory of my friend vladimir m. zakalyukin.
the time - dependent dirac equation is solved using the three - dimensional finite difference - time domain ( fdtd ) method.   the dynamics of the electron wave packet in a vector potential is studied in the arrangements associated with the aharonov - bohm effect.   the solution of the dirac equation showed a change in the velocity of the electron wave packet even in a region where no forces acted on the electron.   the solution of the dirac equation agreed with the prediction of classical dynamics under the assumption that the dynamics was defined by the conservation of generalized or canonical momentum.   it was also shown that in the case when the magnetic field was not zero, the conservation of generalized or canonical momentum was equivalent to the action of the lorentz force.
the @xmath0  bootis stars, a group of late b to early f - type populationi stars, have surface abundances that resemble the general metal depletion pattern found in the interstellar medium.   inspired by the recent result that the fundamental parameters of these peculiar stars differ in no respect from a comparison sample of normal stars, the hypothesis of an interaction between a star and a diffuse interstellar cloud is considered as a possible explanation of the peculiar abundance pattern.   it is found that such a scenario is able to explain the selective accretion of interstellar gas depleted in condensable elements as well as the spectral range of the @xmath0  bootis phenomenon.       stars : abundances  stars : chemically peculiar  accretion
the lattice instabilities of perovskite structure oxides are responsible for many of their interesting properties, such as temperature - dependent ferroelectric phase transitions.   first - principles calculations using linear response theory provide an accurate means to determine the lattice dynamics throughout the entire brillouin zone ( bz ). using the lapw linear response method@xcite,   we have previously carried out such a study on ferroelectric knbo@xmath0@xcite.   we present here the results of a similar investigation for cubic srtio@xmath0.   while knbo@xmath0 has only ferroelectric - type instabilities, srtio@xmath0 exhibits both ferroelectric ( fe ) and antiferrodistortive ( afd ) instabilities.   we correctly predict the known instability at the r - point in the brillouin zone, which is responsible for the afd phase transition to the tetragonal structure at about 105  k. furthermore, the phase space of the ferroelectric instability is greatly reduced compared to knbo@xmath0.   antiferrodistortive instabilities exist in one - dimensional cylindrical tubes extending along the entire r - m - r line in the brillouin zone.   the essentially 1-d character of these tubes corresponds to real - space planar instabilities characterized by rotations of oxygen octahedra.
we report a deficiency of luminous lyman break galaxies ( lbgs ) with a large rest - frame equivalent width ( ew@xmath0 ) of ly@xmath1 emission at @xmath2. combining our spectroscopic sample of lbgs at @xmath3 and those from the literature  , we found that luminous lbgs at @xmath2 generally show weak ly@xmath1 emissions, while faint lbgs show a wide range of ly@xmath1 ew@xmath0 and tend to have strong ( ew@xmath4 ) ly@xmath1 emissions ; i.e., there is a deficiency of strong ly@xmath1 emission in luminous lbgs.   there seems to be a threshold uv luminosity for the deficiency ; it is @xmath5 mag, which is close to or somewhat brighter than the @xmath6 of the uv luminosity function at @xmath3 and 6.   since the large ew@xmath0 of ly@xmath1 emission can be seen among the faint lbgs, the fraction of ly@xmath1 emitters in lbgs may change rather abruptly with the uv luminosity.   if the weakness of ly@xmath1 emission is due to dust absorption, the deficiency suggests that luminous lbgs at @xmath7 tend to be in dusty and more chemically evolved environments and that they start star formation earlier than faint lbgs, though other causes can not be ruled out.
the systematic study of ( anti-)neutrino accompanied @xmath0 decays and @xmath1, @xmath2 electron captures is performed under the assumption of single intermediate nuclear state dominance.   the corresponding half - lives are evaluated both for transitions to the ground state as well as to the @xmath3 and @xmath4 excited states of final nucleus.   it is stressed that the hypothesis of single state dominance can be confirmed or ruled out by the precision measurements of the differential characteristics of the @xmath5-decays of @xmath6 and @xmath7 as well as @xmath1 electron capture in @xmath8, @xmath9 and @xmath10.
we present experimental evidence that a minute amount of polymer additives can significantly enhance heat transport in the bulk region of turbulent thermal convection.   the effects of polymer additives are found to be the _ suppression _ of turbulent background fluctuations that give rise to incoherent heat fluxes that make no net contribution to heat transport, and at the same time to _ increase _ the coherency of temperature and velocity fields.   the suppression of small - scale turbulent fluctuations leads to more coherent thermal plumes that result in the heat transport enhancement.   the fact that polymer additives can increase the coherency of thermal plumes is supported by the measurements of a number of local quantities, such as the extracted plume amplitude and width, the velocity autocorrelation functions and the velocity - temperature cross - correlation coefficient.   the results from local measurements also suggest the existence of a threshold value for the polymer concentration, only above which can significant modification of the plume coherent properties and enhancement of the local heat flux be observed.   estimation of the plume emission rate suggests that the second effect of polymer additives is to stabilize the thermal boundary layers.
a clear detection of excess of power, providing a substantial evidence for solar - like oscillations in the g5 subgiant, is presented.   this star was observed over seven nights with the sarg echelle spectrograph operating with the 3.6-m italian tng telescope, using an iodine absorption cell as a velocity reference.   a clear excess of power centered at 1.2mhz, with peak amplitudes of about 0.9 in the amplitude spectrum is present.   fitting the asymptotic relation to the power spectrum, a mode identification for the @xmath0 modes in the frequency range @xmath1 is derived.   the most likely value for the large separation turns out to be 56.5, consistent with theoretical expectations.   the mean amplitude per mode ( @xmath2 ) at peak power results to be @xmath3, almost three times larger than the solar one.
with the tracking condition, the stability of quintessence solutions are examined.   it is found that there is only one physically relevant fixed point for the system generically.   two specific examples of quintessence potentials are worked out in the frame work.    *   tracking quintessence : a dynamical systems study * + nandan roy and narayan banerjee    _ department of physical sciences,   + indian institute of science and educational research - kolkata,   + mohanpur campus, west bengal 741252, india. _   +    pacs : 98.80.-k ; 95.36.+x
the caltech faint galaxy redshift survey has collected @xmath02000 spectra taken with multi - slit masks using the low resolution imaging spectrograph at the keck observatory ( oke _ et al. _   1995 ) in two widely separated fields on the sky, each @xmath01 x 1 deg@xmath1.   most of these objects are faint field galaxies ; about 10% are galactic stars and about 1% are broad - lined agns.   i summarize the small scale clustering of this sample as well as the evidence in support of large scale structure.
the nature of the cosmic dark matter is unknown.   the most compelling hypothesis is that dark matter consists of weakly interacting massive particles ( wimps ) in the 100 gev mass range.   such particles would annihilate in the galactic halo, producing high - energy gamma rays which might be detectable in gamma ray telescopes such as the glast satellite.   we investigate the ability of glast to distinguish between wimp annihilation sources and astrophysical sources.   focusing on the galactic satellite halos predicted by the cold dark matter model, we find that the wimp gamma - ray spectrum is nearly unique ; separation of the brightest wimp sources from known source classes can be done in a convincing way by including spectral and spatial information.   candidate wimp sources can be further studied with imaging atmospheric cerenkov telescopes.   finally, large hadron collider data might have a crucial impact on the study of galactic dark matter.   slac - pub-12173
we generalized the recently introduced new impurity solver @xcite based on the diagrammatic expansion around the atomic limit and quantum monte carlo summation of the diagrams.   we present generalization to the cluster of impurities, which is at the heart of the cluster dynamical mean - field methods, and to realistic multiplet structure of a correlated atom, which will allow a high precision study of actinide and lanthanide based compounds with the combination of the dynamical mean - field theory and band structure methods.   the approach is applied to both, the two dimensional hubbard and t - j model within cellular dynamical mean field method.   the efficient implementation of the new algorithm, which we describe in detail, allows us to study coherence of the system at low temperature from the underdoped to overdoped regime.   we show that the point of maximal superconducting transition temperature coincides with the point of maximum scattering rate although this optimal doped point appears at different electron densities in the two models.   the power of the method is further demonstrated on the example of the kondo volume collapse transition in cerium.   the valence histogram of the dmft solution is presented showing the importance of the multiplet splitting of the atomic states.
we present a both ultraviolet and infrared regularization independent analysis in a symmetry preserving framework for the @xmath0 super yang - mills beta function to two loop order.   we show explicitly that off - shell infrared divergences as well as the overall two loop ultraviolet divergence cancel out whilst the beta function receives contributions of infrared modes.
we evaluate the effect of screening by bound electron in @xmath0be(p,@xmath1)@xmath2b reaction, where @xmath3be target contains bound electron, in the framework of the adiabatic representation of the three particle problem.   a comparison with two other approximations ( united atom and folding ) is presented. a good agreement between the `` united atom '' approximation and the exact solution   is found.   we also discuss the screening corrections induced by two k - shell electrons on a @xmath3be target.   the bound electron screening effect consequences for @xmath3be and @xmath2b solar neutrino fluxes are discussed.   = 1.0 mm
in many epidemiological models a nonlinear transmission function is used in the form of power law relationship.   it is constantly argued that such form reflects population heterogeneities including differences in the mixing pattern, susceptibility, and spatial patchiness, although the function itself is considered phenomenological.   comparison with large - scale simulations show that models with this transmission function accurately approximate data from highly heterogeneous sources. in this note   we provide a mechanistic derivation of the power law transmission function, starting with a simple heterogeneous susceptibles  infectives ( si ) model, which is based on a standard mass action assumption.   we also consider the simplest si model with separable mixing and compare our results with known results from the literature.    ] keywords : + + + + + + + + +    si epidemiological model, heterogeneous populations, transmission function, power law, separable mixing     ] ams ( mos ) subject classification : + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +    34c20, 34g20, 92d30
spinodal decomposition process in the system of immiscible pbte / cdte compounds is analyzed as an example of a self - organizing structure.   the immiscibility of the constituents leads to the observed morphological transformations like anisotropy driven formation of quantum dots and nanowires, and to the phase separation at the highest temperatures.   proposed model accomplishes bulk and surface diffusion together with the anisotropic mobility of material components.   we analyze its properties by kinetic monte carlo simulations and show that it is able to reproduce all of the structures observed experimentally in the process of pbte / cdte growth.   we show that studied mechanisms of dynamic processes play different role in the creation of zero, one, two and finally three - dimensional structures.   the shape of grown structures is different for relatively thick multilayers when bulk diffusion cooperates with the anisotropic mobility, in annealed structure when isotropic bulk diffusion only decides about the process and finally for thin multilayers when surface diffusion is the most decisive factor.   we compare our results with experimentally grown systems and show that proposed model explains the diversity of observed structures.
we present evidence, based on play - by - play data from all 6087 games from the 2006/072009/10 seasons of the national basketball association ( nba ), that basketball scoring is well described by a continuous - time anti - persistent random walk.   the time intervals between successive scoring events follows an exponential distribution, with essentially no memory between different scoring intervals. by including the heterogeneity of team strengths, we build a detailed computational random - walk model that accounts for a variety of statistical properties of scoring in basketball games, such as the distribution of the score difference between game opponents, the fraction of game time that one team is in the lead, the number of lead changes in each game, and the season win / loss records of each team
we propose a dual cavity fabry - perot interferometer as a wavelength calibrator and a stability tracking device for astronomical spectrograph.   the fpi consists of two adjoining cavities engraved on a low expansion monoblock spacer.   a low - finesse astro - cavity is intended for generating a uniform grid of reference lines to calibrate the spectrograph and a high - finesse lock - cavity is meant for tracking the stability of the reference lines using optical frequency standards.   the differential length changes in two cavities due to temperature and vibration perturbations are quantitatively analyzed using finite element method.   an optimized mounting geometry with fractional length changes @xmath0 is suggested.   we also identify conditions necessary to suppress relative length variations between two cavities well below 10@xmath1  m, thus facilitating accurate dimension tracking and generation of stable reference spectra for doppler measurement at 10 cms@xmath2 level.    ; ; ;
the next - to - leading order analysis for the cross section for hadroproduction of top quark pairs close to threshold is presented. within the framework of non - relativistic qcd a significant enhancement compared to fixed order perturbation theory   is observed which originates from the characteristic remnant of the @xmath0 peak below production threshold of top quark pairs.   the analysis includes all color singlet and color octet configurations of top quark pairs in @xmath1-wave states and, for the dominant configurations, it employs all - order soft gluon resummation for the hard parton cross section.   numerical results for the large hadron collider at @xmath2tev and @xmath3tev and also for the tevatron are presented.   the possibility of a top quark mass measurement from the invariant mass distribution of top quark pairs is discussed.   pacs numbers : 12.38.bx, 12.38.cy, 14.65.ha
using a relativistic transport model art1.0, we explore effects of nuclear symmetry energy on meson production and its rare decay to the dark u - boson in heavy - ion reactions from 0.2 to 10 gev / nucleon available at several current and future facilities.   the yield of mesons at sub - threshold energies is found to be very sensitive to the density dependence of nuclear symmetry energy. above a beam energy of about 5 gev / nucleon in au+au reactions,   the sensitivity to symmetry energy disappears. using the branching ratio of the rare decay ( @xmath0 ) available in the literature  , we estimate the maximum cross section for the u - boson production in the energy range considered, providing a useful reference for future u - boson search using heavy - ion reactions.
here we treat the transmission of disease through a population as a standard galton - watson branching process, modified to take the presence of vaccination into account.   vaccination reduces the number of secondary infections produced per infected individual.   we show that introducing vaccination in a population therefore reduces the expected time to extinction of the infection.   we also prove results relating the distribution of number of secondery infections with and without vaccinations.   department of mathematics and statistics, university of guelph, canada, n1 g 2w1.   * present address : mathematical institute, 24 - 29 st giles, university of oxford, oxford, ox1 3 lb england.   emails : < arni@maths.ox.ac.uk >,   < cbauch@uoguelph.ca >    msc : 60j85.
using mass - selected galaxy samples from deep multiwavelength data we investigate the incidence of close galaxy pairs between @xmath0.   many such close pairs will eventually merge, and the pair fraction is therefore related to the merger rate. over this redshift range   the mean pair fraction is essentially constant ( evolving as @xmath1 ) with about @xmath2% of massive galaxies having a @xmath3 or greater companion within @xmath4kpc. assuming the timescale over which pairs merge is not a strong function of redshift  , this implies a similarly constant merger rate ( per unit time ) out to @xmath5.   since about three times as much cosmic time passes at @xmath6 as between @xmath7, this implies that correspondingly more mergers occur in the low - redshift universe.   when minor companions ( 1:10 mass ratio or greater ) are included, the pair fraction increases to @xmath8% and still does not evolve strongly with redshift.   we also use a rest - frame color criterion to select pairs containing only quiescent galaxies ( major `` dry merger '' progenitors ), and find them to be similarly rare and constant with @xmath9% of massive quiescent galaxies exhibiting a nearby companion.   thus, even though other studies find major mergers to be relatively uncommon since @xmath10, our results suggest that few additional mergers occur in the @xmath11 range and other mechanisms may be required to explain the mass and size growth of galaxies over this epoch.
is an exotic binary system consisting of a @xmath0 b star and a compact object which is probably a neutron star.   the system is associated with the interesting radio source  that exhibits bright radio outbursts with a period of 26.5 days.   we report the results of continuous daily radio interferometric observations of  at 2.25 and 8.3 ghz from 1994 january to 1996 february.   the observations cover 25 complete ( and 3 partial ) cycles with multiple observations each day.   we detect substantial cycle - to - cycle variability of the radio emission characterized by a rapid onset of the radio flares followed by a more gradual decrease of the emission.   we detect a systematic change of the radio spectral index @xmath1 ( defined as @xmath2 ) which typically becomes larger than zero at the onset of the radio outbursts.   this behavior is suggestive of expansion of material initially optically thick to radio frequencies, indicating either that synchrotron or inverse compton cooling are important or that the free - free optical depth to the source is rapidly changing.   after two years of observations, we see only weak evidence for the proposed 4-year periodic modulation in the peak flux of the outbursts.   we observe a secular trend in the outburst phases according the the best published ephemeris.   this trend indicates either orbital period evolution, or a drift in outburst orbital phase in response to some other change in the system.
we study the behavior of quark and diquark condensates in dense quark matter under the influence of a gravitational field adopting as a simple model the static @xmath0dimensional einstein universe.   calculations are performed in the framework of the extended nambu  jona - lasinio model at finite temperature and quark density on the basis of the thermodynamic potential and the gap equations.   quark and diquark condensates as functions of the chemical potential and temperature at different values of the curvature have been studied.   phase portraits of the system have been constructed.
the x-3.4 class flare of 13 december 2006 was observed with a high cadence of 2 minutes at 0.2 arc - sec resolution by hinode / sot fg instrument.   the flare ribbons could be seen in g - band images also.   a careful analysis of these observations after proper registration of images show flare related changes in penumbral filaments of the associated sunspot, for the first time.   the observations of sunspot deformation, decay of penumbral area and changes in magnetic flux during large flares have been reported earlier in the literature. in this _   letter _, we report lateral motion of the penumbral filaments in a sheared region of the @xmath0-sunspot during the x - class flare.   such shifts have not been seen earlier.   the lateral motion occurs in two phases, ( i ) motion before the flare ribbons move across the penumbral filaments and ( ii ) motion afterwards.   the former motion is directed away from expanding flare ribbons and lasts for about four minutes.   the latter motion is directed in the opposite direction and lasts for more than forty minutes.   further, we locate a patch in adjacent opposite polarity spot moving in opposite direction to the penumbral filaments.   together these patches represent conjugate foot - points on either side of the polarity inversion line ( pil ), moving towards each other.   this converging motion could be interpreted as shrinkage of field lines.
multi - wavelength vla observations of two extended radio galaxies, @xmath0 and @xmath1 are presented.   there is some evidence from earlier studies that these two sources exhibit low frequency ( @xmath2ghz ) variability.   this work shows that both sources have linear polarizations, if any, below the detection limits at 320 mhz, so we can not explain the variability as being due to instrumental polarization effects as has been suggested for 3c159.   refractive scintillation may be the cause of the variability in 0235@xmath3197.   this would require the existence of a bright, compact component in one of the hot spots seen in these observations.   this is not implausible but the resolution of this observational program is insufficent to address that question.   the radio source 1203@xmath4043 lacks any bright compact component thereby ruling out a refractive scintillation mechanism for its variability.   consequently, it is possible that claims of variability in this source are spurious.   however, the 320mhz vla observations show that 1203@xmath4043 has an ` x'-shaped radio structure.   this is a rare morphology for the brightness distribution of a radio galaxy ; the implications of this are examined.
we propose a new hypothesis for the origin of the major part of non - solar hadronic cosmic rays ( crs ) at all energies : highly relativistic, narrowly collimated jets from the birth or collapse of neutron stars ( nss ) in our galaxy accelerate ambient disk and halo matter to cr energies and disperse it in hot spots which they form when they stop in the galactic halo.   such events are seen as cosmological gamma - ray bursts ( grbs ) in other galaxies when their beamed radiation happens to point towards earth.   this source of crs is located in the galactic halo.   it therefore explains the absence of the greisen - zatsepin - kuzmin cutoff in the spectrum of the ultra - high energy crs.   the position in energy of the `` ankle '' in the cr energy spectrum is shown to arise in a natural way. moreover  , an origin of lower energy crs in the galactic halo naturally accounts for the high degree of isotropy of crs around 100 tev from airshower observations, and the small galactocentric gradient of low - energy crs derived from gamma - ray observations.
a novel theory of @xmath0 gravity with the lagrangian density @xmath1/(2\kappa^2)$ ] is analyzed.   constant curvature solutions of the model are found, and the potential of the scalar field and the mass of a scalar degree of freedom in einstein s frame are derived.   the cosmological parameters of the model are calculated, which are in agreement with the planck data.   critical points for the de sitter phase and the matter dominated epoch of autonomous equations are obtained and studied.
we have investigated the bimodal distribution of the duration of batse gamma - ray bursts ( grbs ) by analyzing light curves of 64 ms time resolution.   we define the average pulse width of grbs from the auto - correlation function of grb profiles.   the distribution of the average pulse width of grbs is bimodal, suggesting that grbs are composed of long - pulse grbs and short - pulse grbs.   the average pulse width of long - pulse grbs appears correlated with the peak flux, consistent with the time dilation effect anticipated from the cosmological origin of grbs.   however, the correlation between the average pulse width and the peak flux for the short - pulse grbs does nt show such a tendency, which needs further study with higher time resolution data.   email : yuwf@astrosv1.ihep.ac.cn
we introduce a generalized non - uniform mean - field formalism to describe the dissociation of weak rod - like polyelectrolytes ( pes ).   our approach allows for two - sublattice symmetry breaking which in titration curves is associated with a plateau for intermediate dissociation degrees.   we first test our method in the case of a single weak pe by comparison with exact enumeration studies and show that it gives quantitatively accurate results for the dissociation degree in the full range of ph values, and in specific performs much better than the nearest - neighbor approximation ( where exact solutions are possible ).   we then study charge regulation of the coupled system of a weak polyacid and a weak polybase as a function of their mutual distance, which has some relevance for pe - multilayer formation and for pe complexation.   an intricate interplay of the degree of dissociation and the effective interaction between the pes as a function of their mutual distance is found.   +    = 1.5 truecm
the mass structure of hadron multiplets is understood to imply the inexactness of su(3 ) symmetry. here   we show that these symmetry broken mass splittings amongst baryon and meson multiplet members are close integral multiples of the mass difference between a neutral pion and a muon, the first excitation within the elementary particle mass spectrum.   this is found to be equally true for the mass intervals amongst the particles belonging to the multiplets having different spin and parity characteristics.   the results reinforce our earlier contention that the mass difference between a neutral pion and a muon is of fundamental importance to the elementary particle mass distribution.
we consider full perturbations to a covariantly defined schwarzschild spacetime. by constructing complex quantities, we derive two decoupled, covariant and gauge - invariant, wave - like equations for spin - weighted scalars.   these arise naturally from the bianchi identities and comprise a covariant representation of the bardeen - press equations for scalars with spin - weight @xmath0.   furthermore, the covariant and gauge - invariant 1 + 1 + 2 formalism is employed, and consequently, the physical interpretation of the energy - momentum perturbations is transparent.   they are written explicitly in terms of the energy - momentum specified on spacelike three - slices.   ultimately, a cauchy problem is constructed whereby, an initial three - slice may be perturbed by an energy - momentum source, which induces resultant gravitational fields.
open source bioinformatics tools running under ms windows are rare to find, and those running under windows hpc cluster are almost non - existing.   this is despite the fact that the windows is the most popular operating system used among life scientists.   therefore, we introduce in this initiative winbioinftools, a toolkit containing a number of bioinformatics tools running under windows high performance computing server 2008. it is an open source code package, where users and developers can share and add to.   we currently start with three programs from the area of sequence analysis : 1 ) coconut for pairwise genome comparison, 2 ) parallel blast for biological database search, and 3 ) parallel global pairwise sequence alignment. in this report, we focus on technical aspects concerning how some components of these tools were ported from linux / unix environment to run under windows.   we also show the advantages of using the windows hpc cluster 2008.   we demonstrate by experiments the performance gain achieved when using a computer cluster against a single machine.   furthermore, we show the results of comparing the performance of winbioinftools on the windows and linux cluster.     ] * availability : * + + + + + + + + + + + + + + +    winbioinftools is open source package available at the nile university bioinformatics server ( http://www.nubios.nileu.edu.eg/tools/winbioinftools ) and at codeplex ( http://winbioinftools.codeplex.com ).
the beam - beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration.   a current carrying wire has been proposed to compensate long - range beam - beam effects in the lhc and strong localized long - range beam - beam effects are experimentally investigated in the rhic collider.   tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. in this paper  , we report on simulations to study the effect of beam - wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak - strong beam simulation code ( ` bbsimc ` ).   the simulation results are compared with measurements performed in rhic during 2007 and 2008.
we study mobility and interaction of gap solitons in a bose - einstein condensate ( bec ) confined by an optical lattice potential.   such localized wavepackets can exist only in the gaps of the matter - wave band - gap spectrum and their interaction properties are shown to serve as a measure of discreteness imposed onto a bec by the lattice potential.   we show that inelastic collisions of two weakly localized near - the - band - edge gap solitons provide simple and effective means for generating strongly localized in - gap solitons through soliton fusion.
we obtained soar telescope b and v photometry of 14 star clusters and 2 associations in the bridge tidal structure connecting the lmc and smc.   these objects are used to study the formation and evolution of star clusters and associations under tidal stresses from the clouds.   typical star clusters in the bridge are not richly populated and have in general relatively large diameters ( @xmath0pc ), being larger than galactic counterparts of similar age. ages and other fundamental parameters are determined with field - star decontaminated photometry. a self - consistent approach is used to derive parameters for the most - populated sample cluster ngc796 and two young cmd templates built with the remaining bridge clusters.   we find that the clusters are not coeval in the bridge.   they range from approximately a few myr ( still related to optical hii regions and wise and spitzer dust emission measurements ) to about 100 - 200 myr.   the derived distance moduli for the bridge objects ( @xmath1 ) suggests that the bridge is a structure connecting the lmc far - side in the east to the foreground of the smc to the west.   most of the present clusters are part of the tidal dwarf candidate d1, which is associated with an hi overdensity.   we find further evidence that the studied part of the bridge is evolving into a tidal dwarf galaxy, decoupling from the bridge.       ( _ galaxies : ) _ magellanic clouds ; _ galaxies : _ structure ; _ galaxies : _ star clusters : general.
frictional interfaces are abundant in natural and man - made systems and their dynamics still pose challenges of fundamental and technological importance.   a recent extensive compilation of multiple - source experimental data has revealed that velocity - strengthening friction, where the steady - state frictional resistance increases with sliding velocity over some range, is a generic feature of such interfaces.   moreover, velocity - strengthening friction has very recently been linked to slow laboratory earthquakes and stick - slip motion. here   we elucidate the importance of velocity - strengthening friction by theoretically studying three variants of a realistic rate - and - state friction model.   all variants feature identical logarithmic velocity - weakening friction at small sliding velocities, but differ in their higher velocity behaviors. by quantifying energy partition ( e.g. radiation and dissipation ), the selection of interfacial rupture fronts and rupture arrest,   we show that the presence or absence of velocity - strengthening friction can significantly affect the global interfacial resistance and the total energy released during frictional instabilities ( `` event magnitude '' ).   furthermore, we show that different forms of velocity - strengthening friction ( e.g. logarithmic vs. linear ) may result in events of similar magnitude, yet with dramatically different dissipation and radiation rates.   this happens because the events are mediated by interfacial rupture fronts with vastly different propagation velocities, where stronger velocity - strengthening friction promotes slower rupture.   these theoretical results may have significant implications on our understanding of frictional dynamics.
this paper outlines research and development of a new hadoop - based architecture for distributed processing and analysis of electron microscopy of brains.   we show development of a new c++ library for implementation of 3d image analysis techniques, and deployment in a distributed map / reduce framework.   we demonstrate our new framework on a subset of the kasthuri11 dataset from the open connectome project.   brain ; electron microscopy ; connectome ; hadoop ; map / reduce ; service ;
in this paper we introduce a numerical method for solving nonlinear volterra integro - differential equations. in the first step,   we apply implicit trapezium rule to discretize the integral in given equation.   further, the daftardar - gejji and jafari technique ( djm ) is used to find the unknown term on the right side.   we derive existence - uniqueness theorem for such equations by using lipschitz condition.   we further present the error, convergence, stability and bifurcation analysis of the proposed method.   we solve various types of equations using this method and compare the error with other numerical methods.   it is observed that our method is more efficient than other numerical methods  .    0.5 cm sachin bhalekar, jayvant patade + _ department of mathematics, shivaji university, kolhapur - 416004, india. +   email : sachin.math@yahoo.co.in, sbb_maths@unishivaji.ac.in ( sachin bhalekar ), jayvantpatade1195@gmai.com ( jayvant patade ) _   +    keywords : volterra integro - differential equations, trapezium rule, daftardar - gejji and jafari method, numerical solution, error, convergence, stability, bifurcation.
we study a bilayer kane - mele - hubbard model with lattice distortion and inter - layer spin exchange interaction under cylinder geometry.   our analysis based on real - space dynamical mean field theory with continuous - time quantum monte carlo demonstrates the emergence of a topological edge mott insulating ( temi ) state which hosts gapless edge modes only in collective spin excitations.   this is confirmed by the numerical calculations at finite temperatures for the spin - hall conductivity and the single - particle excitation spectrum ; the spin hall conductivity is almost quantized, @xmath0, predicting gapless edge modes carrying the spin current, while the helical edge modes in the single - particle spectrum are gapped out with respecting symmetry.   it is clarified how the temi state evolves from the ordinary spin hall insulating state with increasing the hubbard interaction at a given temperature and then undergoes a phase transition to a trivial mott insulating state. with a bosonization approach at zero temperature, we further address which collective modes host gapless edge modes in the temi state.
stationary thick brane solutions supported by two spinor fields are considered.   two spinor fields are used here to exclude the off - diagonal components of the energy - momentum tensor of the spinor fields.   the trapping of a test scalar field on the brane is also considered.
the fully hadronic final states of two signal processes from an msugra inspired scenario ( susy - p5 ) are studied within a full simulation of the ldc@xmath0 detector model. these are chargino pair and neutralino pair production, i.e. @xmath1 and @xmath2.   both processes have to be separated sufficiently from all background to measure the respective production cross sections and extract the masses of the involved bosinos, @xmath3, @xmath4 and @xmath5.   this is achieved by fitting the energy spectra of the reconstructed gauge bosons while taking into account the finite width of the boson mass. from simulation data corresponding to 500  fb@xmath6 of luminosity,   a mass resolution of about 0.5 gev seems to be achievable.
we study the form factors appearing in the inclusive decay @xmath0, in the framework of the noncommutative standard model. here   @xmath1 denotes the virtual gluon.   we get additional structures and the corresponding form factors in the noncommutative geometry.   we analyse the dependencies of the form factors to the parameter @xmath2 where @xmath3 ( @xmath4 ) are the four momenta of incoming ( outgoing ) @xmath5 quark ( virtual gluon @xmath1 ), @xmath6 is a parameter which measures the noncommutativity of the geometry.   we see that the form factors are weakly sensitive to this parameter.
we report on the results of femtoscopic analysis of pb - pb collisions at @xmath0  tev and pp  collisions at @xmath1, @xmath2 and @xmath3  tev with identical pions and kaons.   detailed femtoscopy studies in heavy - ion collisions at sps and rhic have shown that emission region sizes ( `` hbt radii '' ) decrease with increasing pair transverse momentum @xmath4, which is understood as a manifestation of the collective behavior of matter.   the trend was predicted to persist at the lhc.   the data from pb - pb collisions confirm the existence of a flowing medium and provide strict constraints on the dynamical models.   similar analysis is carried out for pp  collisions for pions and kaons and qualitative similarities to heavy - ion data are seen, especially in collisions producing large number of particles.   the observed trends give insight into the soft particle production mechanism in pp  collisions.   3d radii were also found to universally scale with event multiplicity in heavy - ion collisions.   we extend the range of multiplicities both upwards with the pb - pb data and downwards with the pp  data to test the scaling in new areas. in particular the high multiplicity pp  collisions   reach particle densities comparable to the ones measured in peripheral cu - cu and au - au collisions at rhic.   this allows for the first time to directly compare freeze - out sizes for systems with very different initial states.
renormalization group analysis of boundary conformal field theory on bosonic d25-brane is used to study tachyon condensation. placing the lump on a finite circle and triggering only the first three tachyon modes  , the theory flows to nearby ir fixed point representing lumps that are extended object with definite profile.   the boundary entropy corresponding to the d24-brane tension is calculated in the leading order in perturbative analysis which decreases under rg flow and agrees with the expected result to an accuracy of @xmath0.   multicritical behaviour of the ir theory suggests that the end point of the flow represents a configuration of two d24-branes.   analogy with kondo physics is discussed.   we comment on @xmath1 symmetry restoration.   damtp-2000 - 121 + runhetc-2000 - 41 + hep - th/0010247 +    0.5 cm     + * of tachyon condensation *    1.0 cm    satabhisa dasgupta    0.5 cm    _ department of physics and astronomy, rutgers university, + piscataway, nj 08855, u.s.a.   _    0.5 cm    tathagata dasgupta    0.5 cm    _ department of applied mathematics and theoretical physics + wilberforce road, cambridge, cb3 0wa, u.k. _    1.0 cm
measurement is integral to quantum information processing and communication ; it is how information encoded in the state of a system is transformed into classical signals for further use. in quantum optics, measurements are typically destructive, so that the state is not available afterwards for further steps.   here we show how to measure the presence or absence of the vacuum in a quantum optical field without destroying the state, implementing the ideal projections onto the respective subspaces.   this not only enables sequential measurements, useful for quantum communication, but it can also be adapted to create novel states of light via bare raising and lowering operators.
we calculate the coefficients in the chiral lagrangian approximately from qcd based on a previous study of deriving the chiral lagrangian from the first principles of qcd in which the chiral lagrangian coefficients are defined in terms of certain green s functions in qcd.   we first show that, in the large-@xmath0 limit, the anomaly part contributions to the coefficients are exactly cancelled by certain terms in the normal part contributions, and the final results of the coefficients only concern the remaining normal part contributions depending on qcd interactions.   we then do the calculation in a simple approach with the approximations of taking the large-@xmath0 limit, the leading order in dynamical perturbation theory, and the improved ladder approximation, thereby the relevant green s functions are expressed in terms of the quark self energy @xmath1. by solving the schwinger - dyson equation for @xmath1, we obtain the approximate qcd predicted coefficients and quark condensate which are consistent with the experimental values.   pacs number(s ) : 12.39.fe, 11.30.rd, 12.38.aw, 12.38.lg
a two - slit interference of a massive particle in the presence of environment induced decoherence is theoretically analyzed.   the markovian master equation, derived from coupling the particle to a harmonic - oscillator heat bath, is used to obtain exact solutions which show the existence of an interference pattern.   interestingly, decoherence does not affect the pattern, but only leads to a reduction in the fringe visibility.
we investigate a prototypical agent - based model, the naming game, on random geometric networks.   the naming game is a minimal model, employing local communications that captures the emergence of shared communication schemes ( languages ) in a population of autonomous semiotic agents. implementing the naming games on random geometric graphs, local communications being local broadcasts,   serves as a model for agreement dynamics in large - scale, autonomously operating wireless sensor networks.   further, it captures essential features of the scaling properties of the agreement process for spatially - embedded autonomous agents.   we also present results for the case when a small density of long - range communication links are added on top of the random geometric graph, resulting in a  small - world "- like network and yielding a significantly reduced time to reach global agreement.
until the mystery of confinement is understood from the first principles, so called _ soft physics _ remains an important area of research, providing valuable information on underlying dynamics of strong interactions at long distances. in this review an attempt is made to summarize recent experimental results on multiparticle production in   and on diffraction at hera.   # 1#2#3#4#1*#2 * ( # 4 ) # 3 0_phys.   rev. _ 2df_2^d(3 )    x   lpnhe/9610 + november 1996 +    * soft interactions + and diffraction phenomena * +   +     +   + plenary talk + -2pt given at the 28@xmath0 international conference on high energy physics, + warsaw, 25 - 31 july, 1996
we analyze the two - loop level @xmath0-parity violating supersymmetric contribution to the electric and chromoelectric dipole moments of the fermion with neutrino and gaugino in the intermediate state.   it is found that this contribution can be sufficiently enhanced with large @xmath1 and that it can have comparable size with the currently known @xmath0-parity violating barr - zee type process in the tev scale supersymmetry breaking.   we also give new limits on the @xmath0-parity violating couplings from the experimental data of the electric dipole moments of the neutron and the electron.
the type ia supernovae ( sne ia ) observational data are used to estimate the parameters of a cosmological model with cold dark matter and the generalized chaplygin gas model ( gcgm ).   the gcgm depends essentially on five parameters : the hubble constant, the parameter @xmath0 related to the velocity of the sound, the equation of state parameter @xmath1, the curvature of the universe and the fraction density of the generalized chaplygin gas ( or the cold dark matter ).   the parameter @xmath1 is allowed to take negative values and to be greater than @xmath2.   the bayesian parameter estimation yields @xmath3, @xmath4, @xmath5, @xmath6, @xmath7, @xmath8, @xmath9 and @xmath10, where @xmath11 is the age of the universe and @xmath12 is the value of the deceleration parameter today.   our results indicate that a universe completely dominated by the generalized chaplygin gas is favoured, what reinforces the idea that the this gas may unify the description for dark matter and dark energy, at least as the sne ia data is concerned.   a closed and accelerating universe is also favoured. the traditional chaplygin gas model ( cgm ),   @xmath13 is not ruled out, even if it does not give the best - fitting.   particular cases with four or three independent free parameters are also analysed.   pacs number(s ) : 98.80.bp, 98.80.es, 04.60.gw
donors in silicon are now demonstrated as one of the leading candidates for implementing qubits and quantum information processing.   single qubit operations, measurements and long coherence times are firmly established, but progress on controlling two qubit interactions has been slower.   one reason for this is that the inter donor exchange coupling has been predicted to oscillate with separation, making it hard to estimate in device designs.   we present a multivalley effective mass theory of a donor pair in silicon, including both a central cell potential and the effective mass anisotropy intrinsic in the si conduction band.   we are able to accurately describe the single donor properties of valley - orbit coupling and the spatial extent of donor wave functions, highlighting the importance of fitting measured values of hyperfine coupling and the orbital energy of the @xmath0 levels.   ours is a simple framework that can be applied flexibly to a range of experimental scenarios, but it is nonetheless able to provide fast and reliable predictions.   we use it to estimate the exchange coupling between two donor electrons and we find a smoothing of its expected oscillations, and predict a monotonic dependence on separation if two donors are spaced precisely along the  direction.
biological soft tissues exhibit elastic properties which can be dramatically different from rubber - type materials ( elastomers ). to gain a better understanding of the role of constitutive relationships in determining material responses under loads we compare three different types of instabilities ( two in compression, one in extension ) in hyperelasticity for various forms of strain energy functions typically used for elastomers and for soft tissues.   surprisingly, we find that the strain - hardening property of soft tissues does not always stabilize the material.   in particular we show that the stability analyses for a compressed half - space and for a compressed spherical thick shell can lead to opposite conclusions : a soft tissue material is more stable than an elastomer in the former case and less stable in the latter case.
production of @xmath0 mesons is considered in the course of heavy - ion collisions at sps energies.   we investigate the possible difference in momentum distributions of @xmath0 mesons measured via their leptonic ( @xmath1 ) and hadronic ( @xmath2 ) decays.   rescattering of secondary kaons in the dense hadron gas together with the influence of in - medium kaon potential can lead to a relative decrease of a @xmath0 yield observed in the hadronic channel.   we analyze how the in - medium modifications of meson properties affect apparent - reconstructed momentum distributions of @xmath0 mesons.   quantitative results are presented for central pb+pb collisions at @xmath3.
many creative ideas are being proposed for image sensor designs, and these may be useful in applications ranging from consumer photography to computer vision. to understand and evaluate each new design, we must create a corresponding image processing pipeline that transforms the sensor data into a form that is appropriate for the application.   the need to design and optimize these pipelines is time - consuming and costly.   we explain a method that combines machine learning and image systems simulation that automates the pipeline design.   the approach is based on a new way of thinking of the image processing pipeline as a large collection of local linear filters.   we illustrate how the method has been used to design pipelines for novel sensor architectures in consumer photography applications.   local linear learned, camera image processing pipeline, machine learning
we present a generalization of hilfer derivatives in which riemann  liouville integrals are replaced by more general prabhakar integrals.   we analyze and discuss its properties.   furthermore, we show some applications of these generalized hilfer   prabhakar derivatives in classical equations of mathematical physics such as the heat and the free electron laser equations, and in difference - differential equations governing the dynamics of generalized renewal stochastic processes.   _ keywords _ : hilfer  prabhakar derivatives, prabhakar integrals, mittag  leffler functions, generalized poisson processes
altruistic behaviour is disadvantageous for the individual while is advantageous for its group. if the target of the selection is the individual, one would expect the selection process to lead to populations formed by wholly homogeneous groups, made up of either altruistic or egoistic individuals, where the winning choice depends on the balance beetwen group advantage and individual disadvantage.   we show in a simple model that populations formed by _   inhomogeneous _ groups can be stabilized in some circumstances.   we argue that this condition is realized when there is a relative advantage conferred by the presence of a few altruists to all the members of the group.
we propose a similarity - based method, using the similarity between nodes, to address the problem of classification in partially labeled networks.   the basic assumption is that two nodes are more likely to be categorized into the same class if they are more similar. in this paper, we introduce ten similarity indices, including five local ones and five global ones  . empirical results on the co - purchase network of political books show that the similarity - based method can give high accurate classification even when the labeled nodes are sparse which is one of the difficulties in classification.   furthermore, we find that when the target network has many labeled nodes, the local indices can perform as good as those global indices do, while when the data is spares the global indices perform better.   besides, the similarity - based method can to some extent overcome the unconsistency problem which is another difficulty in classification.   complex networks, similarity, classification, labeled network    89.20.ff, 89.75.hc, 89.65.-s
we present a simple framework to compute hyperbolic voronoi diagrams of finite point sets as affine diagrams.   we prove that bisectors in klein s non - conformal disk model are hyperplanes that can be interpreted as power bisectors of euclidean balls.   therefore our method simply consists in computing an equivalent clipped power diagram followed by a mapping transformation depending on the selected representation of the hyperbolic space ( e.g., poincar conformal disk or upper - plane representations ).   we discuss on extensions of this approach to weighted and @xmath0-order diagrams, and describe their dual triangulations. finally, we consider two useful primitives on the hyperbolic voronoi diagrams for designing tailored user interfaces of an image catalog browsing application in the hyperbolic disk : ( 1 ) finding nearest neighbors, and ( 2 ) computing smallest enclosing balls.   v#1 # 1#2, # 2 # 1 # 1 # 1#2, # 2
two critical points have been revealed in the normal - state phase diagram of the electron - doped cuprate superconductor nd@xmath0ce@xmath1cuo@xmath2 by exploring the fermi surface properties of high quality single crystals by high - field magnetotransport.   first, the quantitative analysis of the shubnikov - de haas effect shows that the weak superlattice potential responsible for the fermi surface reconstruction in the overdoped regime extrapolates to zero at the doping level @xmath3 corresponding to the onset of superconductivity.   second, the high - field hall coefficient exhibits a sharp drop right below optimal doping @xmath4 where the superconducting transition temperature is maximum.   this drop is most likely caused by the onset of long - range antiferromagnetic ordering.   thus, the superconducting dome appears to be pinned by two critical points to the normal state phase diagram.
solving the one - dimensional time - dependent schrdinger equation for simple model potentials, we investigate resonance - enhanced high - order harmonic generation, with emphasis on the physical mechanism of the enhancement. by truncating a long - range potential  , we investigate the significance of the long - range tail, the rydberg series, and the existence of highly excited states for the enhancements in question.   we conclude that the channel closings typical of a short - range or zero - range potential are capable of generating essentially the same effects.
we present a detailed numerical study of the elementary condensation events ( avalanches ) associated to the adsorption of @xmath0he in silica aerogels.   we use a coarse - grained lattice - gas description and determine the nonequilibrium behavior of the adsorbed gas within a local mean - field analysis, neglecting thermal fluctuations and activated processes.   we investigate the statistical properties of the avalanches, such as their number, size and shape along the adsorption isotherms as a function of gel porosity, temperature, and chemical potential.   our calculations predict the existence of a line of critical points in the temperature - porosity diagram where the avalanche size distribution displays a power - law behavior and the adsorption isotherms have a universal scaling form.   the estimated critical exponents seem compatible with those of the field - driven random field ising model at zero temperature.
we investigate the effects of quenched disorder, in the form of site and bond dilution, on the physics of the @xmath0 antiferromagnetic heisenberg model on even - leg ladders.   site dilution is found to prune rung singlets and thus create localized moments which interact via a random, unfrustrated network of effective couplings, realizing a random - exchange heisenberg model ( rehm ) in one spatial dimension.   this system exhibits a power - law diverging correlation length as the temperature decreases.   contrary to previous claims, we observe that the scaling exponent is non - universal, i.e., doping dependent.   this finding can be explained by the discrete nature of the values taken by the effective exchange couplings in the doped ladder.   bond dilution on even - leg ladders leads to a more complex evolution with doping of correlations, which are weakly enhanced in 2-leg ladders, and are even suppressed for low dilution in the case of 4-leg and 6-leg ladders.   we clarify the different aspects of correlation enhancement and suppression due to bond dilution by isolating the contributions of rung - bond dilution and leg - bond dilution.
we present a detailed description of the generalized geometric cluster algorithm for the efficient simulation of continuum fluids  . the connection with well - known cluster algorithms for lattice spin models is discussed, and an explicit full cluster decomposition is derived for a particle configuration in a fluid. we investigate a number of basic properties of the geometric cluster algorithm, including the dependence of the cluster - size distribution on density and temperature.   practical aspects of its implementation and possible extensions are discussed.   the capabilities and efficiency of our approach are illustrated by means of two example studies.
we introduce a two - dimensional, distribution - valued field which we call the _ quadratic field _ associated to the one - dimensional ornstein - uhlenbeck process.   we show that the stationary quadratic fluctuations of the simple exclusion process, when rescaled in the diffusive scaling, converge to this quadratic field.   we show that this quadratic field evaluated at the diagonal corresponds to the wick - renormalized square of the ornstein - uhlenbeck process, and we use this new representation in order to prove some small and large - time properties of it.
previously a theory has been presented which extends the geometrical structure of a real four - dimensional space - time via a field of orthonormal tetrads with an enlarged transformation group.   this new transformation group, called the conservation group, contains the group of diffeomorphisms as a proper subgroup.   field equations were obtained from a variational principle which is invariant under the conservation group. in this paper, this theory is further extended by development of a suitable lagrangian for a field with sources.   spherically symmetric solutions for both the free field and the field with sources are given.   a stellar model and an external, free - field model are developed.   the theory implies that the external stress - energy tensor has non - compact support and hence may give the geometrical foundation for dark matter.   the resulting models are compared to the internal and external schwarzschild models.   the theory may explain the pioneer anomaly and the corona heating problem.
dust production among post - main - sequence stars is investigated in the galactic globular cluster 47 tucanae ( ngc 104 ) based on infrared photometry and spectroscopy.   we identify metallic iron grains as the probable dominant opacity source in these winds.   typical evolutionary timescales of agb stars suggest the mass - loss rates we report are too high.   we suggest that this is because the iron grains are small or elongated and/or that iron condenses more efficiently than at solar metallicity.   comparison to other works suggests metallic iron is observed to be more prevalent towards lower metallicities.   the reasons for this are explored, but remain unclear. meanwhile,   the luminosity at which dusty mass loss begins is largely invariant with metallicity, but its presence correlates strongly with long - period variability.   this suggests that the winds of low - mass stars have a significant driver that is not radiation pressure, but may be acoustic driving by pulsations.
depletion interactions between colloidal particles dispersed in a fluid medium are effective interactions induced by the presence of other types of colloid  . they are not instantaneous but build up in time.   we show by means brownian dynamics simulations that the fluctuations in the depletion force between two guest particles in a host dispersion of differently sized colloids do not decay exponentially with time, but show a power - law dependence.   a simple scaling theory accurately describes the dependence of the magnitude of these fluctuations on time, on the inter - particle distance and on the size ratio of guest and host particles.   the consequences in particular for the dynamics of colloidal mixtures are discussed.
given a causal model of some domain and a particular story that has taken place in this domain, the problem of actual causation is deciding which of the possible causes for some effect actually caused it.   one of the most influential approaches to this problem has been developed by halpern and pearl in the context of structural models. in this paper,   i argue that this is actually not the best setting for studying this problem. as an alternative,   i offer the probabilistic logic programming language of cp - logic.   unlike structural models, cp - logic incorporates the deviant / default distinction that is generally considered an important aspect of actual causation, and it has an explicitly dynamic semantics, which helps to formalize the stories that serve as input to an actual causation problem.
canonical coupling between classical and quantum systems can not result in reversible equations, rather it leads to irreversible master equations.   coupling of quantized non - relativistic matter to gravity is illustrated by a simplistic example.   the heuristic derivation yields the theory of gravity - related decoherence proposed longtime ago by penrose and the author.
we present ccd @xmath0 photometry of the field of the open cluster ngc  6866.   structural parameters of the cluster are determined utilizing the stellar density profile of the stars in the field.   we calculate the probabilities of the stars being a physical member of the cluster using their astrometric data and perform further analyses using only the most probable members.   the reddening and metallicity of the cluster were determined by independent methods.   the lamost spectra and the ultraviolet excess of the f and g type main - sequence stars in the cluster indicate that the metallicity of the cluster is about the solar value.   we estimated the reddening @xmath1 mag using the @xmath2 vs @xmath3 two - colour diagram.   the distance modula, the distance and the age of ngc  6866 were derived as @xmath4 mag, @xmath5 pc and @xmath6 myr, respectively, by fitting colour - magnitude diagrams of the cluster with the parsec isochrones.   the galactic orbit of ngc 6866 indicates that the cluster is orbiting in a slightly eccentric orbit with @xmath7.   the mass function slope @xmath8 was derived by using the most probable members of the cluster.       galaxy : open cluster and associations : individual : ngc 6866  stars : hertzsprung russell ( hr ) diagram
the differential encoding / decoding setup introduced by kiran _ et al _, oggier - hassibi and jing - jafarkhani for wireless relay networks that use codebooks consisting of unitary matrices is extended to allow codebooks consisting of scaled unitary matrices. for such codebooks to be usable in the jing - hassibi protocol for cooperative diversity, the conditions involving the relay matrices and the codebook that need to be satisfied are identified. using the algebraic framework of extended clifford   algebras, a new class of distributed differential space - time codes satisfying these conditions for power of two number of relays and also achieving full cooperative diversity with a low complexity sub - optimal receiver is proposed.   simulation results indicate that the proposed codes outperform both the cyclic codes as well as the circulant codes.   furthermore, these codes can also be applied as differential space - time codes for non - coherent communication in classical point to point multiple antenna systems.   algebra, cooperative diversity, low decoding complexity, space - time coding.
we study x - ray absorption spectra of azobenzene - functionalized self - assembled monolayers ( sams ), investigating excitations from the nitrogen @xmath0 edge.   azobenzene with h - termination and functionalized with groups is considered.   the bethe - salpeter equation is employed to compute the spectra, including excitonic effects, and to determine the character of the near - edge resonances.   our results indicate that core - edge excitations are intense and strongly bound : their binding energies range from about 6 to 4 ev, going from isolated molecules to densely - packed sams.   electron - hole correlation rules these excitations, while the exchange interaction plays a negligible role.
we present a general method to detect nonclassical radiation fields with systems of on - off detectors.   we especially study higher order correlations for the identification of nonclassical radiation.   this allows us to directly characterize quantum correlations by the statistics measured with systems of on - off detectors.   additionally, we generalize our method to multiple detector systems for measurements of correlations between light fields.   we also consider multi - mode radiation fields and isolate nonclassicality in terms of the space time correlations.   finally, we present results for the quantum statistics using on - off detectors operating in nonlinear detection modes.
in this paper, we examine the complex sine - gordon model in the presence of a boundary, and derive boundary conditions that preserve integrability.   we present soliton and breather solutions, investigate the scattering of particles and solitons off the boundary and examine the existence of classical solutions corresponding to boundary bound states.   centre for particle theory    department of mathematical sciences    university of durham    durham dh1 3le, england
we present analytical solutions to three qubits and a single - mode cavity coupling system beyond the rotating - wave approximation ( rwa ).   the zeroth - order approximation, equivalent to the adiabatic approximation, works well for arbitrary coupling strength for small qubit frequency.   the first - order approximation, called the generalized rotating - wave approximation ( grwa ), produces an effective solvable hamiltonian with the same form as the ordinary rwa one and exhibits substantial improvements of energy levels over the rwa even on resonance. based on these analytical eigen - solutions, we study both the bipartite entanglement and genuine multipartite entanglement ( gme ).   the dynamics of these two kinds of entanglements using the grwa are consistent with the numerical exact ones.   interestingly, the well - known sudden death of entanglement occurs in the bipartite entanglement dynamics but not in the gme dynamics.
first principles density functional calculations are used to study the early oxidation stages of the mg(0001 ) surface for oxygen coverages @xmath0 monolayers. it is found that at very low coverages o is incorporated below the topmost mg layer in tetrahedral sites. at higher oxygen - load the binding in on - surface sites is increased but at one monolayer coverage   the on - surface binding is still about 60 mev weaker than for subsurface sites.   the subsurface octahedral sites are found to be unfavorable compared to subsurface tetrahedral sites and to on - surface sites. at higher coverages oxygen   adsorbs both under the surface and up.   our calculations predict island formation and clustering of incorporated and adsorbed oxygen in agreement with previous calculations.   the calculated configurations are compared with the angle - scanned x - ray photoelectron diffraction experiment to determine the geometrical structure of the oxidized mg(0001 ) surface.
we address the maximum attainable rate of fingerprinting codes under the marking assumption, studying lower and upper bounds on the value of the rate for various sizes of the attacker coalition.   lower bounds are obtained by considering typical coalitions, which represents a new idea in the area of fingerprinting and enables us to improve the previously known lower bounds for coalitions of size two and three. for upper bounds,   the fingerprinting problem is modelled as a communications problem.   it is shown that the maximum code rate is bounded above by the capacity of a certain class of channels, which are similar to the multiple - access channel.   converse coding theorems proved in the paper provide new upper bounds on fingerprinting capacity.   it is proved that capacity for fingerprinting against coalitions of size two and three over the binary alphabet satisfies @xmath0 and @xmath1 respectively. for coalitions of an arbitrary fixed size @xmath2   we derive an upper bound @xmath3 on fingerprinting capacity in the binary case@xmath4 finally, for general alphabets, we establish upper bounds on the fingerprinting capacity involving only single - letter mutual information quantities.    digital fingerprinting, channel capacity, multiple - access channel, strong converse theorem.
in this article we present a refined summation theory based on karr s difference field approach.   the resulting algorithms find sum representations with optimal nested depth.   for instance, the algorithms have been applied successively to evaluate feynman integrals from perturbative quantum field theory.   symbolic summation, difference fields, nested depth
based on the model of f / s / f trilayer with atomic thickness  @xcite we discuss the relative roles of pair - breaking and proximity effects, as a function of the exchange field, of disorder and of a finite thickness in the superconducting layer.   the exchange field can be small ( weak ferromagnets ) or large ( strong ferromagnets ) compared to the superconducting gap. with weak ferromagnets we show the existence of a reentrant superconducting gap for the f / s / f trilayer with atomic thickness in the parallel alignment ( equivalent to the f / s bilayer ).   qualitatively small disorder is equivalent to reducing the value of the hopping parameters. in the presence of a finite thickness in the superconducting layer   the superconducting gap in the antiparallel alignment is larger than in the parallel alignment, meaning that pair breaking dominates over the proximity effect.
how do individuals accumulate wealth as they interact economically?   we outline the consequences of a simple microscopic model in which repeated pairwise exchanges of assets between individuals build the wealth distribution of a population.   this distribution is determined for generic exchange rules  transactions that involve a fixed amount or a fixed fraction of individual wealth, as well as random or greedy exchanges. in greedy multiplicative exchange,   a continuously evolving power law wealth distribution arises, a feature that qualitatively mimics empirical observations.
in this article, we investigate the next - to - leading order contribution of the higher - twist feynman diagrams to the large-@xmath0 inclusive pion production cross section in proton - proton collisions and present the general formulae for the higher - twist differential cross sections in the case of the running coupling and frozen coupling approaches.   we compared the resummed next - to - leading order higher - twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading - twist cross section.   the structure of infrared renormalon singularities of the higher twist subprocess cross section and it s resummed expression ( the borel sum ) are found.   it is shown that the resummed result depends on the choice of the meson wave functions used in the calculations.   we discuss the phenomenological consequences of possible higher - twist contributions to the meson production in proton - proton collisions in next - to - leading order at rhic.
globular cluster stars evolving off the main sequence are known to lose mass, and it is expected that some of the lost material should remain within the cluster as an intracluster medium ( icm ).   most attempts to detect such an icm have been unsuccessful.   the multiband imaging photometer for spitzer on the _ spitzer space telescope _ was used to observe eight galactic globular clusters in an attempt to detect the thermal emission from icm dust.   most clusters do not have significant detections at 70  @xmath0 m ; one cluster, ngc  6341, has tentative evidence for the presence of dust, but 90  @xmath0 m  observations do not confirm the detection.   individual 70  @xmath0 m  point sources which appear in several of the cluster images are likely to be background galaxies.   the inferred dust mass and upper limits are @xmath1, well below expectations for cluster dust production from mass loss in red and asymptotic giant branch stars.   this implies that either globular cluster dust production is less efficient, or that icm removal or dust destruction is more efficient, than previously believed.   we explore several possibilities for icm removal and conclude that present data do not yet permit us to distinguish between them.
we study cascaded harmonic generation of hybrid surface plasmons in integrated planar waveguides composed of a graphene layer and a doped - semiconductor slab.   we derive a comprehensive model of cascaded third harmonic generation through phase - matched nonlinear interaction of fundamental, second harmonic and third harmonic plasmonic modes supported by the structure.   we show that hybrid graphene - semiconductor waveguides can simultaneously phase - match these three interacting harmonics, increasing the total third - harmonic output by a factor of 5 compared to the non - cascaded regime.
we suggest a tunable optical device to synthesize fock states and their superpositions starting from a coherent source.   the scheme involves an avalanche triggering photodetector and a ring cavity coupled to a traveling wave through a cross - kerr medium.   low quantum efficiency at the photodetector improves the synthesizing quality at the expense of reducing the synthesizing rate.
we investigate a matter dominated navigation cosmological model.   the influence of a possible drift ( wind ) in the navigation cosmological model makes the spacetime geometry change from riemannian to finslerian.   the evolution of the finslerian universe is governed by the same gravitational field equation with the familiar friedmann - robertson - walker one.   however, the change of space geometry from riemannian to finslerian supplies us a new relation between the luminosity distant and redshift. it is shown that the hubble diagram based on this new relation could account for the observations on distant type ia supernovae.
this paper presents a partial solution to a component of the problem of lexical choice : choosing the synonym most typical, or expected, in context.   we apply a new statistical approach to representing the context of a word through lexical co - occurrence networks.   the implementation was trained and evaluated on a large corpus, and results show that the inclusion of second - order co - occurrence relations improves the performance of our implemented lexical choice program.
we present high resolution ( r = 90,000 ) mid - infrared spectra of m dwarfs.   the mid infrared region of the spectra of cool low mass stars contain pure rotational water vapour transitions that may provide us with a new methodology in the determination of the effective temperatures for low mass stars.   we identify and assign water transitions in these spectra and determine how sensitive each pure rotational water transition is to small ( 25  k ) changes in effective temperature.   we find that, of the 36 confirmed and assigned pure rotational water transitions, at least 10 should be sensitive enough to be used as temperature indicators.   stars : low mass - stars : atmospheres - stars : fundamental parameters - infrared : stars
we report on radio timing and multiwavelength observations of the 4.66  ms redback pulsar j1048 + 2339, which was discovered in an arecibo search targeting the _ fermi_-lat source 3fgl  j1048.6 + 2338.   two years of timing allowed us to derive precise astrometric and orbital parameters for the pulsar.   psr j1048 + 2339 is in a 6-hour binary, and exhibits radio eclipses over half the orbital period and rapid orbital period variations.   the companion has a minimum mass of 0.3 _ @xmath0, and we have identified a @xmath1 variable optical counterpart in data from several surveys.   the phasing of its @xmath2  mag modulation at the orbital period suggests highly efficient and asymmetric heating by the pulsar wind, which may be due to an intrabinary shock that is distorted near the companion, or to the companion s magnetic field channeling the pulsar wind to specific locations on its surface.   we also present gamma - ray spectral analysis of the source and preliminary results from searches for gamma - ray pulsations using the radio ephemeris.
* abstract. *   the paper has 2 main goals :    we propose a variant of the capm based on coherent risk.   in addition to the real - world measure and the risk - neutral measure, we propose the third one : _ the extreme measure_. the introduction of this measure provides a powerful tool for investigating the relation between the first two measures.   in particular, this gives us    a new way of measuring reward ;    a new approach to the empirical asset pricing.   * key words and phrases.   * capm, coherent risk measure, contact measure, efficient frontier, empirical asset pricing, extreme measure, no better choice pricing, real - world measure, reward, risk - neutral measure, security market line, sensitivities.   * capm, rewards, and empirical asset pricing *    with coherent risk    _ * alexander s.  cherny@xmath0,dilip b.  madan@xmath1 * _    _ @xmath0moscow state university _ + _ faculty of mechanics and mathematics _ + _ department of probability theory _ + _ 119992 moscow, russia _   + ` e - mail : cherny@mech.math.msu.su ` + ` webpage : http://mech.math.msu.su/~cherny `    _   @xmath1robert h.  smith school of business _   + _ van munching hall _   + _ university of maryland _ + _ college park,   20742 _ + ` e - mail : dmadan@rhsmith.umd.edu ` + ` webpage : http://www.rhsmith.umd.edu/faculty/dmadan `
applications of discretized light - cone quantization ( dlcq ) to ( 3 + 1)-dimensional yukawa theory with pauli  villars regulators and of supersymmetric dlcq ( sdlcq ) to ( 2 + 1)-dimensional super yang   mills theory are discussed. the ability of these methods to provide wave functions as well as spectra is emphasized.
mira variables, rr lyrae variables, and type ii cepheids all represent evolved states of low - mass stars, and long term observations have revealed that changes in pulsation period occur for each of these classes of variable.   most mira variables show small or no period changes, but a few show large period changes that can plausibly be associated with thermal pulses on the asymptotic red giant branch.   individual rr lyrae stars show period changes that do not accord with the predictions of stellar evolution theory  . this may be especially true for rr lyrae stars that exhibit the blazhko effect.   however, the average period changes of all of the rr lyrae variables within a globular cluster prove a better but still imperfect match for the predictions of evolutionary theory. the observed period changes of short period type ii cepheids ( bl her stars ) as well as those of long period type ii cepheids ( w vir stars ) are in broad agreement with the rates of period changes expected from their evolutionary motions through the instability strip.       2@xmath0 2c  ii 4c  iv 2fe  ii 3fe  iii 1 mg  i 2 mg  ii 2si  ii 4si  iv 2al  ii 3al  iii 1o   i 1n  i 1h  i =
we investigate `` shell structure '' from babylonian times : periodicities and beats in computer - simulated lunar data corresponding to those observed by babylonian scribes some 2500 years ago.   we discuss the mathematical similarity between the babylonians recently reconstructed method of determining one of the periods of the moon with modern fourier analysis and the interpretation of shell structure in finite fermion systems ( nuclei, metal clusters, quantum dots ) in terms of classical closed or periodic orbits.
simbad is the reference database for identification and bibliography of astronomical objects.   it contains identifications, ` basic data ', bibliography, and selected observational measurements for several million astronomical objects.   simbad is developed and maintained by cds, strasbourg.   building the database contents is achieved with the help of several contributing institutes. scanning the bibliography is the result of the collaboration of cds with bibliographers in observatoire de paris ( dasgal ), institut dastrophysique de paris, and observatoire de bordeaux.    when selecting catalogues and tables for inclusion, priority is given to optimal multi - wavelength coverage of the database, and to support of research developments linked to large projects. in parallel,   the systematic scanning of the bibliography reflects the diversity and general trends of astronomical research.   a www interface to simbad is available at :    http://simbad.u-strasbg.fr/simbad.
we study the ground state properties of the kitaev - heisenberg model in a magnetic field and explore the evolution of spin correlations in the presence of non - magnetic vacancies. by means of exact diagonalizations,   the phase diagram without vacancies is determined as a function of the magnetic field and the ratio between kitaev and heisenberg interactions.   we show that in the ( antiferromagnetic ) stripe ordered phase the static susceptibility and its anisotropy can be described by a spin canting mechanism.   this accounts as well for the transition to the polarized phase when including quantum fluctuations perturbatively.   effects of spin vacancies depend sensitively on the type of the ground state. in the liquid phase,   the magnetization pattern around a single vacancy in a small field is determined, and its spatial anisotropy is related to that of _ non - zero _ further neighbor correlations induced by the field and/or heisenberg interactions. in the stripe phase, the joint effect of a vacancy and a small   field breaks the six - fold symmetry of the model and stabilizes a particular stripe pattern.   similar symmetry - breaking effects occur even at zero field due to effective interactions between vacancies.   this selection mechanism and intrinsic randomness of vacancy positions may lead to spin - glass behavior.
a recently proposed _ ab initio _ hartree - fock approach aimed at directly obtaining the wannier functions of a crystalline insulator is applied to polymers.   the systems considered are the lih chain and _ trans_-polyacetylene.   in addition to being the first application of our approach to one - dimensional systems, this work also demonstrates its applicability to covalent systems.   both minimal as well as extended basis sets were employed in the present study and excellent agreement was obtained with the bloch orbital based approaches.   cohesive energies, optimized lattice parameters and the band structure are presented.   localization characteristics of the wannier functions are also discussed.
the production of the standard model ( sm ) higgs boson ( @xmath0 ) plus one jet is compared with that of the lightest scalar higgs boson ( @xmath1 ) plus one jet and that of the pseudoscalar higgs boson ( @xmath2 ) plus one jet.   the latter particles belong to the minimal supersymmetric model ( mssm ).   we include both top and bottom quark loops to lowest order in qcd and investigate the limits of small quark mass and infinite quark mass.   we give results for both the cern large hadron collider ( lhc ) and the fermilab tevatron.
we report on the magnetic properties of with structure, which we have characterized through a series of magnetization and neutron diffraction measurements.   we find that undergoes a phase transition to an antiferromagnetically ordered state with a nel temperature of @xmath0 66 k. the nearest neighbour interactions are ferromagnetic as observed by the positive curie - weiss temperature of @xmath1 51.0 k. we find that the magnetic structure of consists of ferromagnetic sheets, which are stacked antiferromagnetically along the tetragonal _ c_-axis, generally referred to as a - type antiferromagnetic order  . the observed magnitude of the ordered magnetic moment at t = 1.5 k is found to be only 0.20(1)@xmath2/co. already in comparably small magnetic fields of @xmath3(5k ) @xmath4 0.3 t, we observe a metamagnetic transition that can be attributed to spin - rearrangements of, with the moments fully ferromagnetically saturated in a magnetic field of @xmath5(5k ) @xmath4   6.4 t. we discuss the entire experimentally deduced magnetic phase diagram for with respect to its unconventionally weak magnetic coupling.   our study characterizes, which is chemically and electronically posed closely to the superconductors, as a host of versatile magnetic interactions.
due to the mechanism of confinement, as known from quantum chromodynamics, it is difficult to observe individual particles carrying fractional quantum number ( _ e.g. _ quark with fractional electric charge ).   a condensed matter example of fractionalized particles is spinons in quasi - one - dimensional spin systems, which are domain walls in the background of neel configurations carrying spin-@xmath0. using the time - evolving block decimation algorithm  , we visualize the nontrivial spinon dynamics induced by the confine mechanism in a two - leg spin-@xmath0 ladder.   it can be illustrated by a simple single - particle picture of bloch oscillation, not only qualitatively but also quantitatively.   we propose the experimental realization and the real time detection of the spinon dynamics in the ultra - cold boson systems of @xmath1rb.
heterogeneous networks have a key role in the design of future mobile communication networks, since the employment of small cells around a macrocell enhances the network s efficiency and decreases complexity and power demand.   moreover, research on blind interference alignment ( bia ) has shown that optimal degrees of freedom ( dof ) can be achieved in certain network architectures, with no requirement of channel state information ( csi ) at the transmitters.   our contribution is a generalised model of bia in a heterogeneous network with one macrocell with @xmath0 users and @xmath0 femtocells each with one user, by using kronecker ( tensor ) product representation.   we introduce a solution on how to vary beamforming vectors under power constraints to maximize the sum rate of the network and how optimal dof can be achieved over @xmath1 time slots.
we have converted the former solar electrical plant themis ( french pyrenees ) into an atmospheric erenkov detector called celeste, which records gamma rays above @xmath0 ( @xmath1 ). here   we present the first sub-@xmath2 detection by a ground based telescope of a gamma ray source, the crab nebula, in the energy region between satellite measurements and imaging atmospheric erenkov telescopes. at our analysis threshold energy of @xmath3   we measure a gamma ray rate of @xmath4 per minute.   allowing for 30% systematic uncertainties and a 30% error on the energy scale yields an integral gamma ray flux of @xmath5 the analysis methods used to obtain the gamma ray signal from the raw data are detailed.   in addition, we determine the upper limit for pulsed emission to be < 12% of the crab flux at the 99% confidence level, in the same energy range.   our result indicates that if the power law observed by egret is attenuated by a cutoff of form @xmath6 then @xmath7.   this is the lowest energy probed by a erenkov detector and leaves only a narrow range unexplored beyond the energy range studied by egret.
in bilinear r - parity violation ( brpv ), in which the superpotential includes a bilinear term between the lepton doublet and the up - type higgs superfields, a sneutrino lsp can decay into pairs of heavy standard model states ( @xmath0s, @xmath1s, tops or higgs bosons ), neutrinos or different - flavor charged lepton modes ( @xmath2 ).   these finals states can dominate over the traditionally considered bottom pair final state and would lead to unique and novel supersymmetric signals : multileptons events or pairs of heavy standard model fields.   we investigate this possibility and find that the branching ratio into these states dominates when the bilinear term is much smaller than the sneutrino vacuum expectation value for a given sneutrino flavor. when brpv is the only source of neutrino masses these decays can only dominate for one of the sneutrino generations. relaxing   this constraint opens these channels for all three generations.   * lsp sneutrino novel decays * + d. aristizabal sierra@xmath3, d. restrepo@xmath4, s. spinner@xmath5 + @xmath6_ifpa, dep.   ago, universite de liege, bat b5, + _ sart tilman b-4000 liege 1, belgium__. + @xmath7_instituto de fisica, universidad de antioquia, + a.a. 1226, medellin, colombia_. + @xmath8_sissa and infn, sezione di trieste, + via bonomea 265, 34136 trieste, italy_.
we define and study in detail _ utraslow scaled brownian motion ( usbm ) _ characterised by a time dependent diffusion coefficient of the form @xmath0. for unconfined motion the mean squared displacement ( msd ) of usbm exhibits an ultraslow, logarithmic growth as function of time, in contrast to the conventional scaled brownian motion. in an harmonic potential   the msd of usbm does not saturate but asymptotically decays inverse - proportionally to time, reflecting the highly non - stationary character of the process.   we show that the process is weakly non - ergodic in the sense that the time averaged msd does not converge to the regular msd even at long times, and for unconfined motion combines a linear lag time dependence with a logarithmic term.   the weakly non - ergodic behaviour is quantified in terms of the ergodicity breaking parameter. the usbm process is also shown to be ageing : observables of the system depend on the time gap between initiation of the test particle and start of the measurement of its motion.   our analytical results are shown to agree excellently with extensive computer simulations.
abstract    we study the baryon vertex ( bv ) in the presence of medium using dbi action and the force balance condition between bv and the probe branes.   we note that a stable bv configuration exists only in some of the confining backgrounds. for the system of finite density,   the issue is whether there is a canonical definition for the baryon mass in the medium. in this work,   we define it as the energy of the deformed bv satisfying the force balance condition ( fbc ) with the probe brane.   with fbc, lengths of the strings attached to the bv tend to be zero while the compact branes are enlongated to mimic the string.   we attribute the deformation energy of the probe brane to the baryon - baryon interaction.   we show that for a system with heavy quarks the baryon mass drops monotonically as a function of density while it has minimum in case of light quark system.        0.5 cm
the detection of a massive jet - ejection event from ss  433 with rxte is reported.   ss  433 in its high state has been monitored with rxte from 2001/11/09 ( mjd = 52222 ) to 2001/11/25 ( mjd = 52238 ), following a radio flare on 2001/11/02 ( mjd = 52215 ).   an irregular temporal variation with time scales of @xmath0 s appears in the light curve, and the amplitude increases day by day.   this is the first detection of such a fast variation from the source.   in addition to the fast variations, the daily light curve scatters with a time scale of @xmath1day from 2001/11/17 ( mjd = 52230 ).   following the scatter, another radio flare has been detected on 2001/11/22 ( mjd = 52235 ), which has been obviously formed during the x - ray scatter.   this is a preliminary report on a massive jet - ejection event witnessed in x - ray band for the first time.   2@xmath2 1s@xmath3
the possible role of radio agn `` feedback '' in conventional hierarchical cosmological models has become widely discussed.   this paper examines some of the details of how such feedback might work.   a basic requirement is the conversion of radio agn outflow energy into heating of the circumgalactic medium in a time comparable to the relevant cooling times.   first, the class of radio agn relevant to this process is identified as fr - i radio sources.   second, it is argued via comparisons with experimental data that these agn outflows are strongly decelerated and become fully turbulent sonic or subsonic flows due to their interaction with the surrounding medium. using this  , a three - dimensional time dependent calculation of the evolution of such turbulent mhd flows is made to determine the time scale required for conversion of the turbulent energy into heat.   this calculation, when coupled with observational data, suggests that the onset of heating can occur @xmath0 yr after the fully turbulent flow is established, and this time is less than or comparable to the local cooling times in the interstellar or circumgalactic medium for many of these objects.   the location of where heat deposition occurs remains uncertain, but estimates of outflow speeds suggest that heating may occur many tens of kpc from the center of the parent galaxy.   recent observations suggest that such radio agn outflows may become dispersed on much larger scales than previously thought, thus possibly satisfying the requirement that heating occur over a large fraction of the volume occupied by the circumgalactic gas.
relic gravitational waves ( rgws ) leave well - understood imprints on the anisotropies in the temperature and polarization of cosmic microwave background ( cmb ) radiation. in the tt and te information channels, which have been well observed by wmap and planck missions, rgws compete with density perturbations mainly at low multipoles.   it is dangerous to include high - multipole cmb data in the search for gravitational waves, as the spectral indices may not be constants. in this paper  , we repeat our previous work  by utilizing the planck tt and wmap te data in the low - multipole range @xmath0.   we find that our previous result is confirmed with higher confidence.   the constraint on the tensor - to - scalar ratio from planck tt and wmap te data is @xmath1 $ ] ( 68% c.l. ) with the maximum likelihood at around @xmath2. correspondingly, the spectral index at the pivot wavenumber @xmath3mpc@xmath4 is @xmath5, which is larger than 1 at more than @xmath6 level.   so, we conclude that the new released cmb data indicate a stronger hint for the rgws with the amplitude @xmath2, which is hopeful to be confirmed by the imminent bicep and planck polarization data.
the monte carlo simulation of the dynamics of complex molecules produces trajectories with a large number of different configurations to sample configuration space.   it is expected that these configurations can be classified into a small number of conformations representing essential changes in the shape of the molecule.   we present a method to visualize these conformations by point sets in the plane based on a geometrical distance measure between individual configurations.   it turns out that different conformations appear as well - separated point sets.   the method is further improved by performing a cluster analysis of the data set.   the point - cluster representation is used to control a three - dimensional molecule viewer application to show individual configurations and conformational changes.   the extraction of essential coordinates and visualization of molecular shape is discussed.
in this work we have derived the expressions of the mean free path ( mfp ) and emissivity of the neutrinos by incorporating non - fermi liquid ( nfl ) corrections upto next to leading order ( nlo ).   we have shown how such corrections affect the cooling of the neutron star composed of quark matter core.
we show that the laplace - beltrami equation @xmath0 in @xmath1, @xmath2, leads under very moderate assumptions to both the maxwell equations and the conformal eastwood - singer gauge condition on conformally flat spaces including the spaces with a robertson - walker metric.   this result is obtained through a geometric formalism which gives, as byproduct, simplified calculations. in particular, we build an atlas for all the conformally flat spaces considered which allows us to fully exploit the weyl rescalling to minkowski space.   = 1
we study the reconstruction of bandlimited fields from samples taken at unknown but statistically distributed sampling locations.   the setup is motivated by distributed sampling where precise knowledge of sensor locations can be difficult.   periodic one - dimensional bandlimited fields are considered for sampling.   perfect samples of the field at independent and identically distributed locations are obtained.   the statistical realization of sampling locations is _ not known_. first, it is shown that a bandlimited field can not be uniquely determined with samples taken at statistically distributed but unknown locations, even if the number of samples is infinite.   next, it is assumed that the order of sample locations is known. in this case, using insights from order - statistics, an estimate for the field with useful asymptotic properties is designed.   distortion ( mean - squared error ) and central - limit are established for this estimate.
the state of a particle in space and time is characterized by its mass and spin, which therefore determine the inertial properties of the particle.   the coupling of intrinsic spin with rotation is examined and the corresponding inertial effects of intrinsic spin are studied. an experiment to measure directly the spin - rotation coupling via neutron interferometry   is analyzed in detail.
we present a novel method to evaluate the alfvn speed and the magnetic field strength along the streamer plasma sheet in the outer corona.   the method is based on recent observations of streamer waves, which are regarded as the fast kink body mode carried by the plasma sheet structure and generated upon the impact of a fast cme ( coronal mass ejection ) on a nearby streamer.   the mode propagates outwards with a phase speed consisting of two components.   one is the phase speed of the mode in the plasma rest frame, the other is the speed of the solar wind streaming along the plasma sheet.   the former can be well represented by the alfvn speed outside the plasma sheet, according to a linear wave dispersion analysis with a simplified slab model of magnetized plasmas.   the radial profiles of the alfvn speed can be deduced with constraints put on the speed of the solar wind, which is done by making use of the measurements of streamer blobs flowing passively in the wind.   the radial profiles of the strength of the coronal magnetic field can be depicted once the electron density distribution is specified, this is done by inverting the observed polarized brightness data. comparing the diagnostic results corresponding to the first wave trough and the following crest, we find that both the alfvn speed and magnetic field strength at a fixed distance decline with time. this is suggestive of the recovering process of the cme - disturbed corona.
one of the main activities in high - energy and nuclear physics is the search for the so - called quark - gluon plasma, a new state of matter which should have existed a few microseconds after the big bang.   a quark - gluon plasma consists of free color charges, i.e. quarks and gluons, interacting by the strong ( instead of electromagnetic ) force.   theoretical considerations predict that the critical temperature for the phase transition from nuclear matter to a quark - gluon plasma is about 150 - 200 mev. in the laboratory   such a temperature can be reached in a so - called relativistic heavy - ion collision in accelerator experiments. using the color charge instead of the electric charge, the coulomb coupling parameter of such a system is of the order 10 - 30.   hence the quark - gluon plasma is a strongly coupled, relativistic plasma, in which also quantum effects are important. in the present work the experimental and theoretical status of the quark - gluon plasma physics   will be reviewed, emphasizing the similarities and differences with usual plasma physics.   furthermore, the mixed phase consisting of free quarks and gluons together with hadrons ( e.g. pions ) will be discussed, which can be regarded as a complex plasma due to the finite extent of the hadrons.
we present the analysis of two _ suzaku _ observations of at two orbital phases after the periastron passage.   variations in the column density of the line - of - sight absorber are observed, consistent with accretion from a clumpy wind.   in addition to a crsf, multiple fluorescence emission lines were detected in both observations.   the variations in the pulse profiles and the crsf throughout the pulse phase have a signature of a magnetic dipole field. using a simple dipole model we calculated the expected magnetic field values for different pulse phases and were able to extract a set of geometrical angles, loosely constraining the dipole geometry in the neutron star. from the variation of the crsf width and energy  , we found a geometrical solution for the dipole, making the inclination consistent with previously published values.
well - ordered ultrathin films of nio have been prepared on an ag(001 ) substrate using molecular beam epitaxy. with the help of angle - resolved two - photon photoemission ( 2ppe ) a series of image potential states ( ips ) for film thicknesses of 24 monolayers ( ml ) has been identified. by time - resolved 2ppe, the lifetimes of the first three ips and their dependence on the oxide film thickness have been determined. while the lifetimes of the ( n=1 ) ips are all in the range of 2742 fs, the values for the ( n=2 ) ips decrease from 85 fs for 2 ml to 33 fs for 4 ml.   these differences are discussed in terms of a coupling to the layer - dependent electronic structure of the nio ultrathin films.
we discuss the transition paths in a coupled bistable system consisting of interacting multiple identical bistable motifs. we propose a simple model of coupled bistable gene circuits as an example, and   show that its transition paths are bifurcating.   we then derive a criterion to predict the bifurcation of transition paths in a generalized coupled bistable system.   we confirm the validity of the theory for the example system by numerical simulation.   we also demonstrate in the example system that, if the steady states of individual gene circuits are not changed by the coupling, the bifurcation pattern is not dependent on the number of gene circuits.   we further show that the transition rate exponentially decreases with the number of gene circuits when the transition path does not bifurcate, while a bifurcation facilitates the transition by lowering the quasi - potential energy barrier.
i review some of the basic observational details of jets from x - ray binaries, or ` microquasars '.   it is shown that in both ( z and atoll ) ns and bhc systems radio emission, and therefore jet formation, is correlated with the presence of hard ( 30500 kev ) x - ray emission. at @xmath0-ray ( @xmath1 500 kev )   energies, the relation is not so clear.   possible physical connections between the presence of a jet, with a population of relativistic electrons, and the emission of hard x - rays, are briefly discussed.
we report a @xmath0 detection of a 21.82  absorption feature in the direction of the bl lac mrk  421 which is interpreted as o  vii k@xmath1 at @xmath2.   this corresponds to the redshift of a h absorber in a cosmic void detected by hst along the line of sight of the same object.   the 21.82  line proves the existence of warm / hot intergalactic medium ( whim ) outside the local group, in agreement with current models of structure formation in the universe.   the whim at @xmath3 has temperature of @xmath4  k for gas densities in the range @xmath5 atom @xmath6.   we also detect o  vii, o  viii and ne  ix absorption lines with zero velocity, possibly connected with whim in the local group.
we present the detection of molecular gas using co(10 ) line emission and followup h@xmath0 imaging observations of galaxies located in nearby voids.   the co(10 ) observations were done using the 45 m telescope of the nobeyama radio observatory ( nro ) and the optical observations were done using the himalayan chandra telescope ( hct ). although void galaxies lie in the most underdense parts of our universe, a significant fraction of them are gas rich, spiral galaxies that show signatures of ongoing star formation.   not much is known about their cold gas content or star formation properties. in this study we searched for molecular gas in five void galaxies using the nro.   the galaxies were selected based on their relatively higher iras fluxes or h@xmath0 line luminosities.   co(10 ) emission was detected in four galaxies and the derived molecular gas masses lie between @xmath1.   the h@xmath0 imaging observations of three galaxies detected in co emission indicates ongoing star formation and the derived star formation rates vary between from 0.2 - 1.0  m@xmath2, which is similar to that observed in local galaxies.   our study shows that although void galaxies reside in underdense regions, their disks may contain molecular gas and have star formation rates similar to galaxies in denser environments.
we study a general majorana junction, where @xmath0 helical nanowires are connected to a common @xmath1-wave superconductor proximity - inducing majorana bound states in the wires. the normal part of each wire ( @xmath2 ) acts as connected lead, where electrons can tunnel into the respective majorana state @xmath3.   the majorana states at the other end, @xmath4, are coupled to each other by an arbitrary tunnel matrix.   we examine the conditions for even - odd parity effects in the tunnel conductance for various junction topologies.
we present multi - band photometry and multi - epoch spectroscopy of the peculiar type ia supernova ( sn  ia ) 2007qd, discovered by the sdss - ii supernova survey.   it possesses physical properties intermediate to those of the peculiar sn  2002cx and the extremely low - luminosity sn  2008 ha.   optical photometry indicates that it had an extraordinarily fast rise time of @xmath0  days and a peak absolute @xmath1 magnitude of @xmath2 at most, making it one of the most subluminous sn  ia ever observed.   follow - up spectroscopy of sn  2007qd near maximum brightness unambiguously shows the presence of intermediate - mass elements which are likely caused by carbon / oxygen nuclear burning. near maximum brightness, sn  2007qd had a photospheric velocity of only 2800  km  s@xmath3, similar to that of sn  2008 ha but about 4000 and 7000  km  s@xmath3 less than that of sn  2002cx and normal sn  ia, respectively.   we show that the peak luminosities of sn  2002cx - like objects are highly correlated with both their light - curve stretch and photospheric velocities.   its strong apparent connection to other sn  2002cx - like events suggests that sn  2007qd is also a pure deflagration of a white dwarf, although other mechanisms can not be ruled out.   it may be a critical link between sn  2008 ha and the other members of the sn  2002cx - like class of objects.
ontological models are attempts to quantitatively describe the results of a probabilistic theory, such as quantum mechanics, in a framework exhibiting an explicit realism - based underpinning. unlike either the well known quasi - probability representations, or the `` r - p '' vector formalism, these models are contextual and by definition only involve positive probability distributions ( and indicator functions ). in this article   we study how the ontological model formalism can be used to describe arbitrary statistics of a system subjected to a _   finite _ set of preparations and measurements.   we present three models which can describe any such empirical data and then discuss how to turn an indeterministic model into a deterministic one.   this raises the issue of how such models manifest contextuality, and we provide an explicit example to demonstrate this.    in the second half of the paper   we consider the issue of finding ontological models with as few ontic states as possible.
we report the discovery of an ultra - faint star cluster in the constellation of centaurus.   this new stellar system, kim 3, features a half light radius of @xmath0pc and a total luminosity of @xmath1.   approximately 26 stars are identified as candidate member stars down to four magnitudes below the main - sequence turn - off, which makes kim3 the least luminous star cluster known to date. the compact physical size and extreme low luminosity place it close to faint star clusters in the size - luminosity plane.   the stellar population of kim 3 appears to be relatively young ( @xmath2gyr ) and metal - poor ( @xmath3 ) at a heliocentric distance of @xmath4kpc.   the cluster lacks a well - defined center and a small but prominent group of stars consistent with the kim 3 isochrone is present approximately 9.7 pc in projection south of the cluster center.   both are signs of the cluster being in the final stage of tidal disruption.
we solve the homogeneous bethe - salpeter ( hbs ) equation for the scalar, pseudoscalar, vector, and axial - vector bound states of quark and anti - quark in large @xmath0 qcd with the improved ladder approximation in the landau gauge.   the quark mass function in the hbs equation is obtained from the schwinger - dyson ( sd ) equation in the same approximation for consistency with the chiral symmetry.   amazingly, due to the fact that the two - loop running coupling of large @xmath0 qcd is explicitly written in terms of an analytic function, large @xmath0 qcd turns out to be the first example in which the sd equation can be solved in the complex plane and hence the hbs equation directly in the time - like region.   we find that approaching the chiral phase transition point from the broken phase, the scalar, vector, and axial - vector meson masses vanish to zero with the same scaling behavior, all degenerate with the massless pseudoscalar meson.   this may suggest a new type of manifestation of the chiral symmetry restoration in large @xmath0 qcd.
we set new constraints on a seven - dimensional space of cosmological parameters within the class of inflationary adiabatic models.   we use the angular power spectrum of the cosmic microwave background measured over a wide range of @xmath0 in the first flight of the maxima  balloon - borne experiment ( maxima-1 ) and the low @xmath0 results from cobe / dmr.   we find constraints on the total energy density of the universe, @xmath1, the physical density of baryons, @xmath2, the physical density of cold dark matter, @xmath3, and the spectral index of primordial scalar fluctuations, @xmath4, all at the @xmath5 confidence level. by combining our results with measurements of high - redshift supernovae   we constrain the value of the cosmological constant and the fractional amount of pressureless matter in the universe to @xmath6 and @xmath7, at the @xmath5 confidence level.   our results are consistent with a flat universe and the shape parameter deduced from large scale structure, and in marginal agreement with the baryon density from big bang nucleosynthesis.
during development, epithelial tissues undergo extensive morphogenesis based on coordinated changes of cell shape and position over time.   continuum mechanics describes tissue mechanical state and shape changes in terms of strain and stress.   it accounts for individual cell properties using only a few spatially averaged material parameters. to determine the mechanical state and parameters in the _ drosophila _ pupa dorsal thorax epithelium, we sever _ in vivo   _ the adherens junctions around a disk - shaped domain comprising typically hundred cells.   this enables a direct measurement of the strain along different orientations at once. the amplitude and anisotropy of the strain increase during development.   we also measure the stress to viscosity ratio and similarly find an increase in amplitude and anisotropy.   the relaxation time is of order of ten seconds.   we propose a space - time, continuous model of the relaxation.   good agreement with experimental data validates the description of the epithelial domain as a continuous, linear, visco - elastic material.   we discuss the relevant time and length scales.   another material parameter, the ratio of external friction to internal viscosity, is estimated by fitting the initial velocity profile. together, our results contribute to quantify forces and displacements, and their time evolution during morphogenesis.
many core - collapse supernova progenitors are presumed to be in binary systems.   if a star explodes in a binary system, the early supernova light curve can be brightened by the collision of the supernova ejecta with the companion star.   the early brightening can be observed when the observer is in the direction of the hole created by the collision.   based on a population synthesis model, we estimate the fractions of core - collapse supernovae in which the light - curve brightening by the collision can be observed.   we find that @xmath0% of core - collapse supernova light curves can be observed with the collisional brightening.   type  ibc supernova light curves are more likely to be brightened by the collision ( 0.53% ) because of the high fraction of the progenitors being in binary systems and their proximity to the companion stars.   type  ii and iib supernova light curves are less affected ( @xmath1% and @xmath2%, respectively ). although the early, slow light - curve declines of some type  iib and ibc supernovae are argued to be caused by the collision with the companion star ( e.g. sn  2008d ), the small expected fraction, as well as the unrealistically small separation required, disfavour the argument. the future transient survey by the large synoptic survey telescope is expected to detect @xmath3 type ibc supernovae with the early collisional brightening per year, and they will be able to provide information on supernova progenitors in binary systems.       binaries : general  supernovae : general  supernovae : individual ( sn  2008d )
cepheid - based distances to seven type ia supernovae ( sne)-host galaxies have been derived using the standard _   hst key project on the extragalactic distance scale pipeline. for the first time, this allows for a transparent comparison of data accumulated as part of three different _ hst projects, the _ key project, the sandage  type ia sne program, and the tanvir  leo  i group study.   re - analyzing the tanvir  galaxy and six sandage  galaxies we find a mean ( weighted ) offset in true distance moduli of @xmath0mag , 6% in linear distance  in the sense of reducing the distance scale, or increasing h@xmath1. adopting the reddening - corrected hubble relations of suntzeff  ( 1999 ), tied to a zero point based upon sne  1990n, 1981b, 1998bu, 1989b, 1972e and 1960f and the photometric calibration of hill  ( 1998 ), leads to a hubble constant of h@xmath2. adopting the kennicutt  ( 1998 ) cepheid period - luminosity - metallicity dependency decreases the inferred h@xmath1 by 4%.   the h@xmath1 result from type ia sne is now in good agreement, to within their respective uncertainties, with that from the tully - fisher and surface brightness fluctuation relations. _ _ _    # 1to 0pt#1 0h@xmath1
the expected level of @xmath0 absorption in the broad line region ( blr ) radiation field of @xmath1-ray loud flat spectrum radio quasars ( fsrqs ) is evaluated as a function of the location of the @xmath1-ray emission region.   this is done self - consistently with parameters inferred from the shape of the spectral energy distribution ( sed ) in a single - zone leptonic ec - blr model scenario.   we take into account all geometrical effects both in the calculation of the @xmath0 opacity and the normalization of the blr radiation energy density. as specific examples  , we study the fsrqs 3c279 and pks 1510 - 089, keeping the blr radiation energy density at the location of the emission region fixed at the values inferred from the sed.   we confirm previous findings that the optical depth due to @xmath0 absorption in the blr radiation field exceeds unity for both 3c279 and pks 1510 - 089 for locations of the @xmath1-ray emission region inside the inner boundary of the blr.   it decreases monotonically, with distance from the central engine and drops below unity for locations within the blr. for locations outside the blr,   the blr radiation energy density required for the production of gev @xmath1-rays rapidly increases beyond observational constraints, thus making the ec - blr mechanism implausible.   therefore, in order to avoid significant @xmath0 absorption by the blr radiation field, the @xmath1-ray emission region must therefore be located near the outer bounary of the blr.
the morphological types of 5836 galaxies were classified by a visual inspection of color images using the sloan digital sky survey ( sdss ) data release 7 ( dr7 ) to produce a morphology catalog of a representative sample of local galaxies with @xmath0.   the sample galaxies are almost complete for galaxies brighter than @xmath1.   our classification system is basically the same as that of the third reference catalog of bright galaxies with some simplifications for giant galaxies. on the other hand, we distinguish the fine features of dwarf elliptical ( de)-like galaxies to classify five subtypes : de, blue - cored dwarf ellipticals, dwarf spheroidals ( dsph ), blue dwarf ellipticals ( de@xmath2 ), and dwarf lenticulars ( ds0 ).   in addition, we denote the presence of nucleation in de, dsph, and ds0.   elliptical galaxies and lenticular galaxies contribute only @xmath3 and @xmath4 of the local galaxies, respectively, whereas spirals and irregulars contribute @xmath5 and @xmath6, respectively.   the de@xmath2 galaxies, which are a recently discovered population of galaxies, contribute a significant fraction of the dwarf galaxies.   there seem to be structural differences between dsph and de galaxies.   the dsph galaxies are fainter and bluer with a shallower surface brightness gradient than de galaxies.   they also have a lower fraction of galaxies with small axis ratios ( @xmath7 ) than de galaxies. the mean projected distance to the nearest neighbor galaxy   is @xmath8kpc. about @xmath9 of local galaxies   have no neighbors with comparable luminosity within a projected distance of 2mpc.
a large number of optimization algorithms have been developed by researchers to solve a variety of complex problems in operations management area.   we present a novel optimization algorithm belonging to the class of swarm intelligence optimization methods.   the algorithm mimics the decision making process of human groups and exploits the dynamics of this process as an optimization tool for combinatorial problems. in order to achieve this aim,   a continuous - time markov process is proposed to describe the behavior of a population of socially interacting agents, modelling how humans in a group modify their opinions driven by self - interest and consensus seeking. as in the case of a collection of spins,   the dynamics of such a system is characterized by a phase transition from low to high values of the overall consenus ( magnetization ).   we recognize this phase transition as being associated with the emergence of a collective superior intelligence of the population. while this state being active, a cooling schedule is applied to make agents closer and closer to the optimal solution, while performing their random walk on the fitness landscape.   a comparison with simulated annealing as well as with a multi - agent version of the simulated annealing is presented in terms of efficacy in finding good solution on a nk - kauffman landscape. in all cases   our method outperforms the others, particularly in presence of limited knowledge of the agent.
the possible effect of solar variability, accordingly cosmic rays variation on atmospheric physics and chemistry is highly debated over the last years. according to several recent models the induced by cosmic rays atmospheric ionization plays a key role in several different processes. at recent, an apparent effect on minor constituents and aerosols over polar regions during major solar proton events   was observed.   the ion production rate during ground level enhancements is a superposition of the contribution of cosmic rays with galactic and solar origin.   the solar cycle 23 provided several strong ground level enhancements.   the period of end october - beginning of november 2003 was characterized by a strong cosmic ray variability, namely a sequence of three gles was observed.   in addition, there were several forbush decreases, which led to a suppression of galactic cosmic ray flux.   as a consequence the cosmic ray induced ion production in the atmosphere and the corresponding ionization effect were subject of dynamical changes. here   we compute the complex ion production due to cosmic rays during the halloween sequence of ground level enhancements on october - november 2003 and we estimate the ionization effect.   the spectral and angular characteristics of the solar protons are explicitly considered throughout the events as well their time evolution.   the ionization effect during the period is computed at several altitudes above the sea level in a region with @xmath0 @xmath1 1 gv and @xmath0 @xmath1 2 gv.
we investigate the nonclassical properties of output fields propagated through a contradirectional asymmetric nonlinear optical coupler consisting of a linear waveguide and a nonlinear ( quadratic ) waveguide operated by second harmonic generation.   in contrast to the earlier results, all the initial fields are considered weak and a completely quantum mechanical model is used here to describe the system.   perturbative solutions of heisenberg s equations of motion for various field modes are obtained using sen - mandal technique.   obtained solutions are subsequently used to show the existence ofsingle - mode and intermodal squeezing, single - mode and intermodal antibunching, two - mode and multi - mode entanglement in the output of contradirectional asymmetric nonlinear optical coupler.   further, existence of higher order nonclassicality is also established by showing the existence of higher order antibunching, higher order squeezing and higher order entanglement.   variation of observed nonclassical characters with different coupling constants and phase mismatch is discussed.   kishore thapliyal@xmath0, anirban pathak@xmath1, biswajit sen@xmath2, and jan @xmath3@xmath4    @xmath0jaypee institute of information technology, a-10, sector-62, noida, up-201307, india    @xmath5rcptm, joint laboratory of optics of palacky university and institute of physics of academy of science of the czech republic, faculty of science, palacky university, 17.   listopadu 12, 771 46 olomouc, czech republic    @xmath2department of physics, vidyasagar teachers training college, midnapore-721101, india    @xmath6
chains of first - order susy transformations for the spin equation are studied in detail.   it is shown that the transformation chains are related with a polynomial pseudo - supersymmetry of the system.   simple determinant formulas for the final hamiltonian of a chain and for solutions of the spin equation are derived.   applications are intended for a two - level atom in an electromagnetic field with a possible time - dependence of the field frequency. for   a specific form of this dependence, the time oscillations of the probability to populate the excited level disappear. under certain conditions   this probability becomes a function tending monotonously to a constant value which can exceed @xmath0.   pacs : 03.65.fd, 11.30.pb
we use the self - consistent model technique developed by martn - manjn et al.   ( 2008 ) that combines the chemical evolution with stellar population synthesis and photo - ionization codes, to study the star formation scenarios capable of reproducing the observed properties of star - forming galaxies.   the comparison of our model results with a database of hii galaxies shows that the observed spectra and colors of the present burst and the older underlying population are reproduced by models in a bursting scenario with star formation efficiency involving close to 20 per cent of the total mass of gas, and inter - burst times longer than 100myr, and more probably around 1gyr.   other modes like gasping and continuous star formation are not favored.       galaxies : evolution  galaxies : star formation galaxies : starburst galaxies : ism  ism : hii regions
if light hidden sector photons ( @xmath0s ) exist, they could be produced through kinetic mixing with solar photons in the ev energy range.   we propose to search for this hypothetical @xmath0-flux with the super - kamiokande and/or upgraded cast detectors.   the proposed experiments are sensitive to the @xmath1 mixing strength as small as @xmath2 for the @xmath0 mass region @xmath3 ev and, in the case of non - observation, would improve limits recently obtained from photon regeneration laser experiments for this mass region.    * on search for ev hidden sector photons + in super - kamiokande and cast experiments. *   sergei n.  gninenko@xmath4 and javier redondo@xmath5 + _   @xmath4institute for nuclear research of the russian academy of sciences, + 117312 moscow, russia + @xmath5 deutsches elektronen - synchrotron desy + notkestrasse 85, d-22607 hamburg, germany _
quantum entanglement is a concept commonly used with reference to the existence of certain correlations in quantum systems that have no classical interpretation.   it is a useful resource to enhance the mutual information of memory channels or to accelerate some quantum processes as, for example, the factorization in shor s algorithm.   moreover, entanglement is a physical observable directly measured by the von neumann entropy of the system. we have used this concept in order to give a physical meaning to the electron correlation energy in systems of interacting electrons.   the electronic correlation is not directly observable, since it is defined as the difference between the exact ground state energy of the many  electrons schrdinger equation and the hartree  fock energy.   we have calculated the correlation energy and compared with the entanglement, as functions of the nucleus  nucleus separation using, for the hydrogen molecule, the configuration interaction method.   then, in the same spirit, we have analyzed a dimer of ethylene, which represents the simplest organic conjugate system, changing the relative orientation and distance of the molecules, in order to obtain the configuration corresponding to maximum entanglement.    *   key words*. entanglement ; electron correlation energy ; interacting molecules.
we investigate the dynamics of a plasmonic oscillation over a metal nanoparticle when it is strongly coupled to a quantum emitter ( e.g. quantum dot, molecule ).   we simulate the density matrix evolution for a simple model ; coupled classical  quantum oscillators system.   we show that lifetime of the plasmonic oscillations can be increased several orders of magnitude, upto the decay time of the quantum emitter.   this effect shows itself as the narrowing of the plasmon emission band in the spaser ( surface plasmon amplification by stimulated emission of radiation ) experiment , where a gold nanoparticle interacts with the surrounding molecules.   enhancement of the plasmonic excitation lifetime enables stimulated emission to overcome the spontaneous one.   the enhancement occurs due to the emergence of a phenomenon analogous to electromagnetically induced transparency ( eit ).   the effect can find applications in many areas of nanoscale physics, such as in quantum information with plasmons and in increasing solar cell efficiency.
gate instability / hysteresis in modulation - doped p - type algaas / gaas heterostructures impedes the development of nanoscale hole devices, which are of interest for topics from quantum computing to novel spin physics.   we present an extended study conducted using custom - grown, matched modulation - doped n - type and p - type heterostructures, with / without insulated gates, aimed at understanding the origin of the hysteresis.   we show the hysteresis is not due to the inherent ` leakiness'of gates on p - type heterostructures, as commonly believed.   instead, hysteresis arises from a combination of gaas surface - state trapping and charge migration in the doping layer.   our results provide insights into the physics of si acceptors in algaas / gaas heterostructures, including widely - debated acceptor complexes such as si - x.   we propose methods for mitigating the gate hysteresis, including poisoning the modulation - doping layer with deep - trapping centers ( e.g., by co - doping with transition metal species ), and replacing the schottky gates with degenerately - doped semiconductor gates to screen the conducting channel from gaas surface - states.
we revise the lvy s construction of brownian motion as a simple though still rigorous approach to operate with various gaussian processes. a brownian path is explicitly constructed as a linear combination of wavelet - based `` geometrical features '' at multiple length scales with random weights.   such a wavelet representation gives a closed formula mapping of the unit interval onto the functional space of brownian paths.   this formula elucidates many classical results about brownian motion ( e.g., non - differentiability of its path ), providing intuitive feeling for non - mathematicians.   the illustrative character of the wavelet representation, along with the simple structure of the underlying probability space, is different from the usual presentation of most classical textbooks.   similar concepts are discussed for fractional brownian motion, ornstein - uhlenbeck process, gaussian free field, and fractional gaussian fields.   wavelet representations and dyadic decompositions form the basis of many highly efficient numerical methods to simulate gaussian processes and fields, including brownian motion and other diffusive processes in confining domains.
there now exists in the literature two different expressions for the phase shift of a matter - wave interferometer caused by the passage of a gravitation wave.   the first, a commonly accepted expression that was first derived in the 1970s, is based on the traditional geodesic equation of motion ( eom ) for a test particle.   the second, a more recently derived expression, is based on the geodesic deviation eom.   the power - law dependence on the frequency of the gravitational wave for both expressions for the phase shift is different, which indicates fundamental differences in the physics on which these calculations are based.   here we compare the two approaches by presenting a series of side - by - side calculations of the phase shift for one specific matter - wave - interferometer configuration that uses atoms as the interfering particle. by looking at the low - frequency limit of the different expressions for the phase shift obtained,   we find that the phase shift calculated via the geodesic deviation eom is correct, and the ones calculated via the geodesic eom are not.
i review recent activity in the field of intermediate polars, concentrating on : the mode of accretion ( disc - fed, disc - overflow or discless ) ; accretion curtains ( the transition region and the accretion footprint ) ; x - ray pulse profiles ( occultation and absorption effects ) ; accretion columns ( mass determinations, line - broadening, the soft x - ray component ), and outbursts in intermediate polars.   # 1 # 1@xmath0 # 1@xmath1 # 1@xmath2
the damped quantum search proposed in [ a. mizel _ phys.   rev.   lett. _ * 102 * 150501 ( 2009 ) ] was analyzed by calculating the highest possible probability of finding the target state in each iteration.   a new damping parameter that depends on the number of iterations was obtained, this was compared to the critical damping parameter for different values of target to database size ratio.   the result shows that the range of the new damping parameter as a function of the target to database size ratio increases as the number of iterations is increased.   furthermore, application of the new damping parameter per iteration on the damped quantum search scheme shows a significant improvement on some target to database size ratio ( i.e. @xmath0 maximum percentage difference ) over the critically damped quantum search.
the nonlinear theory of collective plasmon - polariton propagation along the infinite chain of metallic nanoparticles is developed within rpa quasiclassical approach to surface plasmons in large nano - spheres ( @xmath0 nm for radius ) of au or ag.   the wave type self - modes in the chain are determined and analyzed with respect to nano - sphere size and chain - separation parameters. at some regions for parameters   the undamped modes occur.   they were found on the rim of stability within the linear theory.   the nonlinear corrections stabilize, however, diverging modes of the linear approach and considerably enlarge the region of undamped propagation.   nonlinearity is associated with relativistic corrections to the lorentz friction. according to the nonlinear behavior  , the region of parameters when undamped stable modes occur, covers the instability region of the linear theory.   the remarkable property of fixed amplitude of the undamped collective propagating wave independently of initial conditions ( even if they are extremely small ) has been identified and described.   the group velocity of this wave propagation is calculated.
we investigate a double quantum dot coupled to a transmission line resonator. by driving a current through the double dot  , a population inversion between the dot levels can be created, and a lasing state of the radiation field is generated within a sharp resonance window.   the transport current correlates with the lasing state.   the sharp resonance condition allows for resolving small differences in the dot properties.   dissipative processes in the quantum dots and their effect on the lasing and transport behavior are investigated.
we investigate the stability of asymptotically anti - de sitter gravity coupled to tachyonic scalar fields with mass at or slightly above the breitenlohner - freedman bound.   the boundary conditions in these `` designer gravity '' theories are defined in terms of an arbitrary function @xmath0.   previous work had suggested that the energy in designer gravity is bounded below if i ) @xmath0 has a global minimum and ii ) the scalar potential admits a superpotential @xmath1.   more recently, however, certain solutions were found ( numerically ) to violate the proposed energy bound.   we resolve the discrepancy by observing that a given scalar potential can admit two possible branches of the corresponding superpotential, @xmath2.   when there is a @xmath3 branch, we rigorously prove a lower bound on the energy ; the @xmath4 branch alone is not sufficient. our numerical investigations i )   confirm this picture, ii ) confirm other critical aspects of the ( complicated ) proofs, and iii ) suggest that the existence of @xmath3 may in fact be necessary ( as well as sufficient ) for the energy of a designer gravity theory to be bounded below.
we review the present knowledge of the diffuse galactic synchrotron emission in polarisation. at microwave frequencies, we assess the expected contamination to the cmb polarisation angular power spectrum, for @xmath0 and @xmath1 modes, as expected after the wmap first year measurements.   cosmology, cosmic microwave background
new method for finding exact solutions of nonlinear differential equations is presented.   it is based on constructing the polygon corresponding to the equation studied.   the algorithms of power geometry are used.   the method is applied for finding one  parameter exact solutions of the generalized korteveg   de vries  burgers equation, the generalized kuramoto - sivashinsky equation, and the fifth  order nonlinear evolution equation.   all these nonlinear equations contain the term @xmath0.   new exact solitary waves are found.    _   keywords : _ the simplest equation method, travelling wave, exact solution, power geometry, the korteveg  de vries  burgers equation, the kuramoto   sivashinsky equation, nonlinear differential equation. +   pacs : 02.30.hq - ordinary differential equations
the system psr j0737 - 3039 is the only binary pulsar known to consist of two radio pulsars ( psr j0737 - 3039 a and psr j0737 - 3039 b ).   this unique configuration allows measurements of spin orientation for both pulsars : pulsar a s spin is tilted from the orbital angular momentum by _ no more than _ 14 degrees at 95% confidence ; pulsar b s by @xmath0 degrees at @xmath1% confidence.   this spin - spin misalignment requires that the origin of most of b s present - day spin is connected to the supernova that formed pulsar b. under the simplified assumption of a single, instantaneous kick during the supernova, the spin could be thought of as originating from the off - center nature of the kick, causing pulsar b to tumble to its misaligned state. with this assumption, and using current constraints on the kick magnitude  , we find that pulsar b s instantaneous kick must have been displaced from the center of mass of the exploding star by at least 1 km and probably 510 km.   regardless of the details of the kick mechanism and the process that produced pulsar b s current spin, the measured spin - spin misalignment in the double pulsar system provides an empirical, direct constraint on the angular momentum production in this supernova.   this constraint can be used to guide core - collapse simulations and the quest for understanding the spins and kicks of compact objects.
pulsars provide unique probes of the large - scale interstellar magnetic field in the galactic disk. up to now  , the limited galactic distribution of the known pulsar population has restricted these investigations to within a few kiloparsec of the sun.   the parkes multibeam pulsar survey has discovered many more - distant pulsars which enables us for the first time to explore the magnetic field in most of the nearby half of the galactic disk.   here we report the detection of counterclockwise magnetic fields in the norma spiral arm using pulsar rotation measures.   the fields are coherent in direction over a linear scale of @xmath0 kpc along the arm and have a strength of @xmath1 @xmath2 g. the magnetic field between the carina - sagittarius and crux - scutum arms   is confirmed to be coherent from @xmath3 to @xmath4 over a length of @xmath5 kpc.   these results strengthen arguments for a bisymmetric spiral model for the field configuration in the galactic disk.
the interaction radius of a resonance is an important physical quantity to describe the structure of a resonance.   but, for a long time, physicists do not find a reliable way to measure the magnitude of the interaction radius of a resonance. in this paper, a method   is proposed to measure the interaction radius in physics analysis.   it is found that the centrifugal barrier effects have great influence to physical results obtained in the pwa fit, and the interaction radius of some resonances can be well measured in the fit.
we analytically discuss the resonance conditions among several neutrinos in matter.   the discriminant for the characteristic equation of the hamiltonian is expressed by the coefficients of the equation.   the result of the computation for the discriminants tells us that the neutrino energy and the matter density are in inverse proportion to each other at the resonance states in not only 2- but also 3- and 4-neutrino models.
in minimal anomaly - mediated supersymmetry breaking models, tachyonic sleptons are avoided by introducing a common scalar mass similar to the one introduced in minimal supergravity.   this may lead to non - minimal flavour - violating interactions,, in the squark sector. in this paper  , we analyze the viable anomaly - mediated supersymmetry breaking parameter space in the light of the latest limits on low - energy observables and lhc searches, complete our analytical calculations of flavour - violating supersymmetric particle production at hadron colliders with those related to gluino production, and study the phenomenological consequences of non - minimal flavour violation in anomaly - mediated supersymmetry breaking scenarios at the lhc.   related cosmological aspects are also briefly discussed.   = 1
we present a detailed study of grb090111, focusing on its extra soft power - law photon index @xmath0 at the very steep decay phase emission ( power - law index @xmath1, steeper than 96% of grbs detected by _ swift _ ) and the following peculiar x - ray re - brightening.   our spectral analysis supports the hypothesis of a comoving band spectrum with the the peak of the @xmath2 spectrum evolving with time to lower values : a period of higher temporal variability in the 1 - 2 kev light - curve ends when the @xmath3 evolves outside the energy band.   the x - ray re - brightening shows extreme temporal properties when compared to a homogeneous sample of 82 early flares detected by swift.   while an internal origin can not be excluded, we show these properties to be consistent with the energy injection in refreshed shocks produced by slow shells colliding with the fastest ones from behind, well after the internal shocks that are believed to give rise to the prompt emission have ceased.       gamma - ray : bursts  radiation mechanism : non - thermal x - rays : individual ( grb090111 ).
cluster variables have recently revolutionized numerical work in certain models involving fermionic variables.   this novel representation of fermionic partition functions is continuing to find new applications. after describing results from a study of a two dimensional hubbard type model that confirm a superconducting transition in the kosterlitz - thouless universality class,   we show how a cluster type algorithm can be devised to study the chiral limit of strongly coupled lattice gauge theories with staggered fermions.
the infrared spectrograph ( irs ) onboard the spitzer space telescope ( sst ) has been used to obtain low and moderate resolution spectra of the dust and gas - rich quasar apm  08279 + 5255 ( z=3.91 ).   broad paschen  @xmath0 and @xmath1 recombination lines of hydrogen were detected at wavelengths of 9.235 and 6.315@xmath2 m, as well as a strong, red continuum that is a smooth power law over the observed ( rest frame ) wavelength range 5.3 - 35@xmath2 m ( 1.08 - 7.1@xmath2 m ).   the observed p@xmath0/p@xmath1 line flux ratio of 1.05@xmath30.2 is far from the case b value of @xmath42 and simple models of high density, high optical depth ionized gas regions ( @xmath41.8 ).   this deviation is opposite in sense to the expected effect of reddening.   no evidence is found in the spectrum for either the 3.3@xmath2 m or 6.2@xmath2 m emission features usually attributed to aromatic hydrocarbons in gas rich galaxies in the local universe.   this is consistent with the high luminosity agn nature of apm  08279 + 5255.
we develop a potentially practical proposal for robust quantum state transfer ( qst ) between two superconducting qubits coupled by a coplanar waveguide ( cpw ) resonator.   we show that the partial measurement could drastically enhance the fidelity even when the dissipation of qubits and cpw is considered. unlike many other schemes for qst, our proposal does not require the couplings between the qubits and the cpw resonator to be strong.   in fact, our method works much more efficiently in the weak coupling regime.   the underlying mechanism is attributed to the probabilistic nature of partial measurement.
in a recent paper [ vaikuntanathan and jarzynski, phys. rev.   e * 83 *, 061120 ( 2011 ) ] a model was introduced whereby work could be extracted from a thermal bath by measuring the energy of a particle that was thermalized by the bath and manipulating the potential of the particle in the appropriate way, depending on the measurement outcome.   if the extracted work is @xmath0 and the work @xmath1 needed to be dissipated in order to erase the measured information in accordance with landauer s principle, it was shown that @xmath2 in accordance with the second law of thermodynamics. here   we extend this work in two directions : first, we discuss how accurately the energy should be measured. by increasing the accuracy   one can extract more work, but at the same time one obtains more information that has to be deleted.   we discuss what are the appropriate ways of optimizing the balance between the two and find optimal solutions.   second, whenever @xmath0 is strictly less than @xmath1 it means that an irreversible step has been performed.   we identify the irreversible step and propose a protocol that will achieve the same transition in a reversible way, increasing @xmath0 so that @xmath3.
the competition between @xmath0-wave superconductivity ( sc ) and antiferromagnetism ( af ) in the high-@xmath1 cuprates is investigated by studying the hole- and electron - doped two - dimensional hubbard model with a recently proposed variational quantum - cluster theory.   the approach is shown to provide a thermodynamically consistent determination of the particle number, provided that an overall shift of the on - site energies is treated as a variational parameter.   the consequences for the single - particle excitation spectra and for the phase diagram are explored. by comparing the single - particle spectra with quantum monte - carlo ( qmc ) and experimental data  , we verify that the low - energy excitations in a strongly - correlated electronic system are described appropriately.   the cluster calculations also reproduce the overall ground - state phase diagram of the high - temperature superconductors. in particular,   they include salient features such as the enhanced robustness of the antiferromagnetic state as a function of electron doping and the tendency towards phase separation into a mixed antiferromagnetic - superconducting phase at low - doping and a pure superconducting phase at high ( both hole and electron ) doping.
it has recently been shown that the marginalization paradox  ( mp ) can be resolved by interpreting improper inferences as probability limits.   the key to the resolution is that probability limits need not satisfy the formal bayes law, which is used in the mp to deduce an inconsistency. in this paper,   i explore the differences between probability limits and the more familiar pointwise limits, which do imply the formal bayes law, and show how these differences underlie some key differences in the interpretation of the mp.   address = theoretical division, ms b213 + los alamos national laboratory + los alamos, nm 87545 + ` tcw@lanl.gov `
we develop a general theory of a boson decomposition for both local and non - local interactions in lattice fermion models which allows us to describe fermionic degrees of freedom and collective charge and spin excitations on equal footing.   an efficient perturbation theory in the interaction of the fermionic and the bosonic degrees of freedom is constructed in so - called dual variables in the path - integral formalism.   this theory takes into account all local correlations of fermions and collective bosonic modes and interpolates between itinerant and localized regimes of electrons in solids.   the zero - order approximation of this theory corresponds to extended dynamical mean - field theory ( edmft ), a regular way to calculate nonlocal corrections to edmft is provided.   it is shown that dual ladder summation gives a conserving approximation beyond edmft.   the method is especially suitable for consideration of collective magnetic and charge excitations and allows to calculate their renormalization with respect to `` bare '' rpa - like characteristics.   general expression for the plasmonic dispersion in correlated media is obtained. as an illustration   it is shown that effective superexchange interactions in the half - filled hubbard model can be derived within the dual - ladder approximation.   correlation effects, collective excitations, path integral 71.27.+a, 71.45.gm, 74.20.mn
dirac structures unify both presymplectic and poisson structures, which serve an implicit generalization of lagrangian and hamiltonian systems including the case of non - holonomic mechanics as well as the case of degenerate lagrangians.   it is known that a dirac structure represents a power conserving interconnection structure between physical systems. in this paper  , we investigate the interconnection of distinct dirac structures and associated physical systems.   first, we make a brief review on induced dirac structures and lagrange - dirac dynamical systems.   second, we consider how distinct dirac structures @xmath0 can be interconnected through a dirac structure @xmath1. to do this, we introduce a tensor product called the _ bowtie product _, @xmath2, of dirac structures and   then show that the interconnection of dirac structures can be given by @xmath3.   we also explore variational structures associated to the interconnection of lagrange - dirac systems.   lastly, we demonstrate the theory of interconnection of dirac structures and associated lagrange - dirac dynamical systems by some examples including electric circuits, nonholonomic mechanical systems, and simple mass - spring mechanical systems.   _ dedicated to the memory of jerrold e. marsden + _
the ground state of hemispherical permalloy magnetic shell is studied.   there exist two magnetic phases : the onion state and the vortex one.   the phase diagram is systematically analyzed in a wide range of geometrical parameters.   possible transitions between different phases are analyzed using the combination of analytical calculations and micromagnetic simulations.    2
pulsar wind nebulae ( pwne ) are suggested to be acceleration sites of cosmic rays in the galaxy.   while the magnetic field plays an important role in the acceleration process, previous observations of magnetic field configurations of pwne are rare, particularly for evolved systems.   we present a radio polarization study of the `` snail '' pwn inside the supernova remnant g327.1@xmath01.1 using the australia telescope compact array.   this pwn is believed to have been recently crushed by the supernova ( sn ) reverse shock.   the radio morphology is composed of a main circular body with a finger - like protrusion.   we detected a strong linear polarization signal from the emission, which reflects a highly ordered magnetic field in the pwn and is in contrast to the turbulent environment with a tangled magnetic field generally expected from hydrodynamical simulations.   this could suggest that the characteristic turbulence scale is larger than the radio beam size.   we built a toy model to explore this possibility, and found that a simulated pwn with a turbulence scale of about one - eighth to one - sixth of the nebula radius and a pulsar wind filling factor of 5075% provides the best match to observations.   this implies substantial mixing between the sn ejecta and pulsar wind material in this system.
a pioneering experiment  reported the measurement of the transmission phase of an electron traversing a quantum dot and found the intriguing feature of a sudden phase drop in the conductance valleys. based on the friedel sum rule for a spinless effective one - dimensional system,   it has been previously argued [ h.- w.   lee, phys.   rev.   lett. * 82 *, 2358 ( 1999 ) ] that the sudden phase drop should be accompanied by the vanishing of the transmission amplitude, or transmission zero. here   we address roles of strong electron - electron interactions on the electron transport through a two - level quantum dot where one level couples with the leads much more strongly than the other level does [ p. g. silvestrov and y. imry, phys.   rev.   let.   * 85 *, 2565 ( 2000 ) ].   we perform a perturbative conductance calculation with an explicit account of large charging energy and verify that the resulting conductance exhibits the transmission zero, in agreement with the analysis based on the friedel sum rule.
nitrogen vacancy ( nv ) centers can couple to confined phonons in diamond mechanical resonators via the effect of lattice strain on their energy levels.   access to the strong spin - phonon coupling regime with this system requires resonators with nanoscale dimensions in order to overcome the weak strain response of the nv ground state spin sublevels. in this work, we study nvs in diamond cantilevers with lateral dimensions of a few hundred nm.   coupling of the nv ground state spin to the mechanical mode is detected in electron spin resonance ( esr ), and its temporal dynamics are measured via spin echo.   our small mechanical mode volume leads to a 10 - 100@xmath0 enhancement in spin - phonon coupling strength over previous nv - strain coupling demonstrations.   this is an important step towards strong spin - phonon coupling, which can enable phonon - mediated quantum information processing and quantum metrology.
because the magnetorotational instability is capable of exponentially amplifying weak preexisting magnetic fields, it might be hoped that the character of the magnetic field in accretion disks would be independent of the nature of the seed field.   however, the divergence - free nature of magnetic fields in highly conducting fluids ensures that their large - scale topology is preserved, no matter how greatly the field intensity is changed. by performing global two - dimensional and three - dimensional general relativistic magnetohydrodynamic disk simulations with several different topologies for the initial magnetic field  , we explore the degree to which the character of the flows around black holes depends on the initial topology.   we find that while the qualitative properties of the accretion flow are nearly independent of field topology, jet - launching is very sensitive to it : a sense of vertical field consistent for at least an inner disk inflow time is essential to the support of strong jets.
we have studied the dynamics of chloride and potassium ions in the interior of the ompf porin under the influence of an external electric field. from the results of extensive all - atom molecular dynamics simulations of the system we computed several first passage time ( fpt ) quantities to characterize the dynamics of the ions in the interior of the channel.   such fpt quantities obtained from md simulations demonstrate that it is not possible to describe the dynamics of chloride and potassium ions inside the whole channel with a single constant diffusion coefficient.   however, we showed that a valid, statistically rigorous, description in terms of a constant diffusion coefficient @xmath0 and an effective deterministic force @xmath1 can be obtained after appropriate subdivison of the channel in different regions suggested by the x - ray structure.   these results have important implications for popular simplified descriptions of channels based on the 1d poisson - nernst - planck ( pnp ) equations.   also, the effect of entropic barriers on the diffusion of the ions is identified and briefly discussed.
transition charge density ( tcd ) for @xmath0 excitation have been calculated for @xmath1 nuclei within microscopic variational framework employing @xmath2 and @xmath3 valence space.   the calculated tcds for different monopole variants of kuo interaction are compared with available experimental results.   other systematics like reduced transition probabilities b(e2 ) and static quadrupole moments q(2 ) are also presented.   it is observed that the transition density study acts as a sensitive probe for discriminating the response of different parts of effective interactions. + keywords : hartree fock bogoliubov, effective interactions, transition charge density + pacs nos : 21.60.-n, 21.10.-k, 23.20.-g, 27.50.+e +
the phylogenetic tree space, introduced by billera, holmes, and vogtmann, is a cone over a simplicial complex. in this short article  , we construct this complex from local gluings of classical polytopes, the associahedron and the permutohedron.   its homotopy is also reinterpreted and calculated based on polytope data.   = 1
a systematic approach to the description of gauge invariant charges is presented and applied to the construction of both the static colour charge configuration in qcd and the monopole solution in pure su(2 ).   the gauge invariant non - abelian monopole offers a new style of order parameter for monopole condensation.
white dwarf luminosities are powerful age indicators, whose calibration should be based on reliable models.   we discuss the uncertainty of some chemical and physical parameters and their influence on the age estimated by means of white dwarf cooling sequences.   models at the beginning of the white dwarf sequence have been obtained on the base of progenitor evolutionary tracks computed starting from the zero age horizontal branch and for a typical halo chemical composition ( z=0.0001, y=0.23 ).   the uncertainties due to nuclear reaction rates, convection, mass loss and initial chemical composition are discussed.   then, various cooling sequences for a typical white dwarf mass ( m=0.6 m@xmath0 ) have been calculated under different assumptions on some input physics, namely : conductive opacity, contribution of the ion - electron interaction to the free energy and microscopic diffusion.   finally we present the evolution of white dwarfs having mass ranging between 0.5 and 0.9 m@xmath0.   much effort has been spent to extend the equation of state down to the low temperature and high density regime.   an analysis of the latest improvement in the physics of white dwarf interiors is presented.   we conclude that at the faint end of the cooling sequence ( @xmath1 ) the present overall uncertainty on the age is of the order of 20%, which correspond to about 3 gyr.   we suggest that this uncertainty could be substantially reduced by improving our knowledge of the conductive opacity ( especially in the partially degenerate regime ) and by fixing the internal stratification of c and o.
this presentation briefly summarizes the recent measurements of @xmath0-values in low energy @xmath1 annihilation.   the new experiments aimed at reducing the uncertainties in @xmath0-values and performed with the upgraded beijing spectrometer ( besii ) at beijing electron positron collider ( bepc ) in beijing and with cmd-2 and snd at veep-2 m in novosibirsk are reviewed and discussed.   = 150truemm = 240truemm -1.0 cm    # 1#1    psfig.sty    plus 1pt minus 1pt
we present the results of optical photometry of the recurrent nova ci aql in later phase of the outburst which occurred in 2000.   our observation revealed that the object reached the quiescent level between 2001 december and 2002 april and therefore that ci aql is a unique recurrent nova characterized by an extremely long ( 1.41.7  yr ) plateau phase.   the light curve obtained in the outburst suggests that the object is the first example of an intermediate between classical novae and recurrent novae. in comparison with estimation given in published theoretical calculations,   the long duration of the plateau phase supports a higher hydrogen content of the white - dwarf envelope, while such an abundance of hydrogen requires a later cessation of the wind which is in disagreement with the sudden fading observed in late november of 2000.   the light curve obtained in later phase of the outburst indicates that the object was fainter and the gradual decline was steeper than predicted.   these discrepancies between the observation and theoretical prediction require drastic modification of the present model of ci aql.       accretion, accretion discs  novae, cataclysmic variables  stars : individual ( ci aql )
the self - consistent tilted axis cranking covariant density functional theory based on the point - coupling interaction pc - pk1 is applied to investigate the possible existence of antimagnetic rotation in the nucleus @xmath0fe.   the observed data for band 3 and band 4 are reproduced well with two assigned configurations.   it is found that both bands correspond to a rotation of antimagnetic character, but, due to the presence of considerable deformation, the interplay between antimagnetic rotation and collective motion plays an essential role.   in particular for band 4, collective rotation is dominant in the competition with antimagnetic rotation.   moreover, it is shown that the behavior of the ratios between the dynamic moments of inertia and the @xmath1 values reflects the interplay between antimagnetic and collective rotation.
the paper address the realization and identification problem for a subclass of piecewise - affine hybrid systems.   the paper provides necessary and sufficient conditions for existence of a realization, a characterization of minimality, and an identification algorithm for this subclass of hybrid systems.   the considered system class and the identification problem are motivated by applications in systems biology.   ,    realization theory, minimization, identification, hybrid systems, network topology, gene - protein networks.
the unique ultra - relativistic, massless, nature of electron states in two - dimensional extended graphene sheets, brought about by the honeycomb lattice arrangement of carbon atoms in two - dimensions, provides ingress to explorations of fundamental physical phenomena in graphene nanostructures. here   we explore the emergence of new behavior of electrons in atomically precise segmented graphene nanoribbons ( gnrs ) and graphene rings with the use of tight - binding calculations, non - equilibrium green s function transport theory, and a newly developed dirac continuum model that absorbs the valence - to - conductance energy gaps as position - dependent masses, including topological - in - origin mass - barriers at the contacts between segments. through transport investigations in variable - width segmented gnrs with armchair,   zigzag, and mixed edge terminations we uncover development of new fabry - prot - like interference patterns in segmented gnrs, a crossover from the ultra - relativistic massless regime, characteristic of extended graphene systems, to a massive relativistic behavior in narrow armchair gnrs, and the emergence of nonrelativistic behavior in zigzag - terminated gnrs.   evaluation of the electronic states in a polygonal graphene nanoring under the influence of an applied magnetic field in the aharonov - bohm regime, and their analysis with the use of a relativistic quantum - field theoretical model, unveils development of a topological - in - origin zero - energy soliton state and charge fractionization.   these results provide a unifying framework for analysis of electronic states, coherent transport phenomena, and the interpretation of forthcoming experiments in segmented graphene nanoribbons and polygonal rings.
we calculate the angular correlation function for a sample of @xmath0170,000 agn extracted from the _ wide - field infrared survey explorer _ ( _ wise _ ) catalog, selected to have red mid - ir colors ( @xmath1 ) and 4.6  @xmath2 m flux densities brighter than 0.14  mjy ). the sample is expected to be @xmath3 reliable at identifying agn, and to have a mean redshift of @xmath4. in total, the angular clustering of _ wise _  agn is roughly similar to that of optical agn.   we cross - match these objects with the photometric sdss catalog and distinguish obscured sources with @xmath5 from bluer, unobscured agn. obscured sources present a higher clustering signal than unobscured sources.   since the host galaxy morphologies of obscured agn are not typical red sequence elliptical galaxies and show disks in many cases, it is unlikely that the increased clustering strength of the obscured population is driven by a host galaxy segregation bias. by using relatively complete redshift distributions from the cosmos survey, we find obscured sources at @xmath6 have a bias of @xmath7 and are hosted in dark matter halos with a typical mass of @xmath8.   in contrast, unobscured agn at @xmath9 have a bias of @xmath10 and inhabit halos of @xmath11.   these findings suggest that obscured agn inhabit denser environments than unobscured agn, and are difficult to reconcile with the simplest agn unification models, where obscuration is driven solely by orientation.
we study the particle number production and its time variation using non - equilibrium quantum field theory.   we study the model proposed by hotta et.al.   @xcite for particle number production with a heavy neutral scalar and a light complex scalar.   the interaction lagrangian contains cp violating phase and particle number violating interaction among the scalars.   the particle number violating mass term is also introduced, which splits a complex scalar into two real scalars with small non - degenerate mass.   therefore, the term generates particle and anti - particle mixing.   we study the long time behavior of the particle number production rate.    2
near critical catalyst - reactant branching processes with controlled immigration are studied.   the reactant population evolves according to a branching process whose branching rate is proportional to the total mass of the catalyst.   the bulk catalyst evolution is that of a classical continuous time branching process ; in addition there is a specific form of immigration.   immigration takes place exactly when the catalyst population falls below a certain threshold, in which case the population is instantaneously replenished to the threshold.   such models are motivated by problems in chemical kinetics where one wants to keep the level of a catalyst above a certain threshold in order to maintain a desired level of reaction activity. a diffusion limit theorem for the scaled processes   is presented, in which the catalyst limit is described through a reflected diffusion, while the reactant limit is a diffusion with coefficients that are functions of both the reactant and the catalyst.   stochastic averaging principles under fast catalyst dynamics are established. in the case where the catalyst evolves `` much faster '' than the reactant, a scaling limit, in which the reactant is described through a one dimensional sde with coefficients depending on the invariant distribution of the reflected diffusion, is obtained.   proofs rely on constrained martingale problem characterizations, lyapunov function constructions, moment estimates that are uniform in time and the scaling parameter and occupation measure techniques.
nuclear stellar clusters are a common phenomenon in spirals and in starbursts galaxies, and they may be a natural consequence of the star formation processes in the central regions of galaxies.   hst uv imaging of a few seyfert 2 galaxies have resolved nuclear starbursts in seyfert 2 revealing stellar clusters as the main building blocks of the extended emission.   however, we do not know whether stellar clusters are always associated with all types of nuclear activity.   we present nuv and optical images provided by hst to find out the role that stellar clusters play in different types of agns ( seyferts and llagns ). also with these images  , we study the circumnuclear dust morphology as a probe of the circumnuclear environment of agns.
landauer s erasure, thermodynamics, classical and quantum error correction, entanglement classical and quantum error correction are presented in the form of maxwell s demon and their efficiency analyzed from the thermodynamic point of view.   we explain how landauer s principle of information erasure applies to both cases. by then extending this principle to entanglement manipulations we rederive upper bounds on purification procedures thereby linking the  no local increase of entanglement  principle to the second law of thermodynamics.
thermophysical properties of hydrogen, helium, and hydrogen - helium mixtures have been investigated in the warm dense matter regime at electron number densities ranging from @xmath0/m@xmath1 and temperatures from 4000 to 20000 k via quantum molecular dynamics simulations.   we focus on the dynamical properties such as the equation of states, diffusion coefficients, and viscosity. mixing rules ( density matching, pressure matching, and binary ionic mixing rules )   have been validated by checking composite properties of pure species against that of the fully interacting mixture derived from qmd simulations.   these mixing rules reproduce pressures within 10% accuracy, while it is 75 % and 50 % for the diffusion and viscosity, respectively.   binary ionic mixing rule moves the results into better agreement.   predictions from one component plasma model are also provided and discussed.
lhc searches for new physics focus on combinations of hard physics objects. in this work   we propose a qualitatively different _ soft _ signal for new physics at the lhc  the `` anomalous underlying event ''.   every hard lhc event will be accompanied by a soft underlying event due to qcd and pile - up effects.   though it is often used for qcd and monte carlo studies, here we propose the incorporation of an underlying event analysis in some searches for new physics.   an excess of anomalous underlying events may be a smoking - gun signal for particular new physics scenarios such as `` quirks '' or `` hidden valleys '' in which large amounts of energy may be emitted by a large multiplicity of soft particles.   we discuss possible search strategies for such soft diffuse signals in the tracking system and calorimetry of the lhc experiments.   we present a detailed study of the calorimetric signal in a concrete example, a simple quirk model motivated by folded supersymmetry. in these models   the production and radiative decay of highly excited quirk bound states leads to an `` antenna pattern '' of soft unclustered energy. using a dedicated simulation of a toy detector and a `` cmb - like '' multipole analysis we compare the signal to the expected backgrounds.   +   +   +     +      +     +   +    ` roni@slac.stanford.edu `,   ` twizansk@slac.stanford.edu `
we present a new sample of compact steep spectrum ( css ) sources with radio luminosity below @xmath0 at 1.4ghz called the low luminosity compact ( llc ) objects.   the sources have been selected from first survey and observed with merlin at l - band and c - band.   the main criterion used for selection was luminosity of the objects and approximately one third of the css sources from the new sample have a value of radio luminosity comparable to fris.   about 80@xmath1 of the sources have been resolved and about 30@xmath1 of them have weak extended emission and disturbed structures when compared with the observations of higher luminosity css sources.   we studied correlation between radio power and linear size, and redshift with a larger sample that included also published samples of compact objects and large scale friis and fris.   the low luminosity compact objects occupy the space in radio power versus linear size diagram below the main evolutionary path of radio objects.   we suggest that many of them might be short - lived objects, and their radio emission may be disrupted several times before becoming friis.   we conclude that there exists a large population of short - lived low luminosity compact objects unexplored so far and part of them can be precursors of large scale fris.       galaxies : active  galaxies : evolution
we discuss examples of d - branes probing toric singularities, and the computation of their world - volume gauge theories from the geometric data of the singularities.   we consider several such examples of d - branes on partial resolutions of the orbifolds @xmath0,@xmath1 and @xmath2.   psfig.sty    hep - th/0005166 + tifr / th/00 - 22   + may, 2000    * d - brane gauge theories from toric singularities of the form @xmath3 and @xmath4 * + tapobrata sarkar + _ department of theoretical physics, + tata institute of fundamental research, + homi bhabha road, mumbai 400 005, india _ +
we investigate the short - time dynamics of a delta - function potential barrier on an initially confined wave - packet.   there are mainly two conclusions : a ) at short times the probability density of the first particles that passed through the barrier is unaffected by it.   b ) when the barrier is absorptive ( i.e., its potential is imaginary ) it affects the transmitted wave function at shorter times than a real potential barrier.   therefore, it is possible to distinguish between an imaginary and a real potential barrier by measuring its effect at short times only on the transmitting wavefunction.
one of the main aims of present and upcoming high energy heavy ion collision experiments is to study new phases of matter at extreme temperature and density.   it is expected that a nontrivial classical pion field configuration can occasionally form during the out - of - equilibrium chiral phase transition.   we have recently shown that, contrarily to what has been assumed so far, this configuration is not identical to the so - called disoriented chiral condensate ( dcc ), proposed in the early 1990 s.   a detailed analysis reveals that a more realistic picture is that of an `` unpolarized '' dcc, where the fourier modes of the field have completely independent orientations in isospin space instead of being aligned with each other as in the original dcc.   this has important implications concerning the possible detection of the phenomenon.   in particular, the main expected signature of the original dcc, which is used in most experimental searches, is absent in the unpolarized case.   we point out that the fact that no evidence of dcc formation has been reported so far in nuclear collisions actually agrees with our present theoretical understanding.   new experimental strategies should be designed to look for the unpolarized dcc in existing data from sps as well as in future searches at rhic and lhc.
we investigate the possibility that the galactic dark matter exists in an scenario where the phantom field is responsible for the dark energy.   we obtain the statically and spherically approximate solution for this kind of the galaxy system with a supermassive black hole at its center.   the solution of the metric functions is satisfied with @xmath0.   constrained by the observation of the rotational stars moving in circular orbits with nearly constant tangential speed in a spiral galaxy, the background of the phantom field which is spatially inhomogeneous has an exponential potential. to avoid the well - known quantum instability of the vacuum at high frequencies,   the phantom field defined in an effective theory is valid only at low energies. under this assumption  , we further investigate the following properties.   the absorption cross section of the low - energy @xmath1-wave excitations of the phantom field into the central black hole is shown to be the horizontal area of the central black hole. because the infalling phantom particles have a total negative energy, the accretion of the phantom energy is related to the decrease of the black hole mass which is estimated to be much less than a solar mass in the lifetime of the universe. using a simple model with the cold dark matter   very weakly coupled to the `` _ low - frequency _ '' phantom particles which are generated from the background, we show that these two densities can be quasi - stable in the galaxy.   cycu - hep-12 - 04
our study presents experimental measurements of the contact and longitudinal voltage drops in hall bars, as a function of the current amplitude.   we are interested in the heating phenomenon which takes place before the breakdown of the quantum hall effect, i.e. the pre - breakdown regime.   two types of samples has been investigated, at low temperature ( 4.2 and 1.5k ) and high magnetic field ( up to 13 t ).   the hall bars have several different widths, and our observations clearly demonstrate that the size of the sample influences the heating phenomenon. by measuring the critical currents of both contact and longitudinal voltages, as a function of the filling factor ( around @xmath0 )  , we highlight the presence of a high electric field domain near the source contact, which is observable only in samples whose width is smaller than 400 microns.    quantum hall effect, pre - breakdown, contact resistance 73.40.hm, 73.40.cg, 73.61.ey, 72.80.ey
we study chiral vorton production for witten - type superconducting string models in the context of a recently developed analytic formalism.   we delineate three distinct scenarios : first, a low energy regime ( including the electroweak scale ) where vortons can be a source of dark matter. secondly, an intermediate energy regime where the vorton density is too high to be compatible with the standard cosmology ( thereby excluding these models ). finally, a high energy regime ( including the gut scale ) in which no vortons are expected to form.   the vorton density is most sensitive to the order of the string - forming phase transition and relatively insensitive to the current - forming transition. for a second - order string transition,   vorton production is cosmologically disastrous for the range @xmath0 ( @xmath1 ), while for the first - order case we can only exclude @xmath2 ( @xmath3 ).   we provide a fitting formula which summarises our results.
the rs cvn - type binary @xmath0 geminorum was observed during a large, long - duration flare simultaneously with _   xmm - newton _ and the vla.   the light curves show a characteristic time dependence that is compatible with the neupert effect observed in solar flares : the time derivative of the x - ray light curve resembles the radio light curve.   this observation can be interpreted in terms of a standard flare scenario in which accelerated coronal electrons reach the chromosphere where they heat the cool plasma and induce chromospheric evaporation.   such a scenario can only hold if the amount of energy in the fast electrons is sufficient to explain the x - ray radiative losses.   we present a plausibility analysis that supports the chromospheric evaporation model.
we derive the fundamental plane ( fp ) relation for a sample of 1430 early - type galaxies in the optical ( r band ) and the near - infrared ( k band ), by combining sdss and ukidss data. with such a large, homogeneous dataset, we are able to assess the dependence of the fp on the waveband.   our analysis indicates that the fp of luminous early - type galaxies is essentially waveband independent, with its coefficients increasing at most by @xmath0 from the optical to the nir.   this finding fits well into a consistent picture where the tilt of the fp is not driven by stellar populations, but results from other effects, such as non - homology. in this framework,   the optical and nir fps require more massive galaxies to be slightly more metal rich than less massive ones, and to have highly synchronized ages, with an age variation per decade in mass smaller than a few percent.
a portion of the hep community has perceived the need for a minimization package written in c++ and taking advantage of the object - oriented nature of that langauge. to be acceptable for hep, such a package must at least   encompass all the capabilities of minuit. aside from the slight plus of not relying on outside fortran compilation,   the advantages that a c++ package based on o - o design would confer over the multitude of available c++ minuit - wrappers include : easier extensibility to different algorithms and forms opf constraints ; and usage modes which would not be available in the global - common - based minuit design.   an example of the latter is a job persuing two ongoing minimization problems simultaneously.   we discuss the design and implementation of such a package, which extends minuit only in minor ways but which greatly diminishes the programming effort ( if not the algorithm thought ) needed to make more significant extensions.
the structure and evolution of grain boundaries underlies the nature of polycrystalline materials.   here we describe an experimental apparatus and light reflection technique for measuring disorder at grain boundaries in optically clear material, in thermodynamic equilibrium.   the approach is demonstrated on ice bicrystals.   crystallographic orientation is measured for each ice sample.   the type and concentration of impurity in the liquid can be controlled and the temperature can be continuously recorded and controlled over a range near the melting point. the general methodology is appropriate for a wide variety of materials.    _   copyright 2009 american institute of physics.   this article may be downloaded for personal use only.   any other use requires prior permission of the author and the american institute of physics.   the following article appeared in review of scientific instruments ( vol.80, issue 10 ) and may be found at _ http://link.aip.org/link/?rsi/80/103903.
we construct non - stationary exact solutions to five dimensional einstein - maxwell - chern - simons theory with positive cosmological constant.   the solutions are based on four - dimensional atiyah - hitchin space. in asymptotic regions, the solutions approach to gibbons - perry - sorkin monopole solutions. on the other hand, near the four - dimensional bolt of atiyah - hitchin space,   our solutions show a bolt structure in five dimensions.   the c - function for the solutions shows monotonic increase in time, in agreement with the general expected behaviour of c - function in asymptotically ds spacetimes.    * cosmological solutions on atiyah - hitchin space in five dimensional einstein - maxwell - chern - simons theory * +    a. m. ghezelbash + department of physics and engineering physics, + university of saskatchewan, + saskatoon, saskatchewan s7n 5e2, canada +
linear chains of quantum scatterers are studied in the process of lengthening, which is treated and analysed as a discrete dynamical system defined over the manifold of scattering matrices.   elementary properties of such dynamics relate the transport through the chain to the spectral properties of individual scatterers. for a single - scattering channel case   some new light is shed on known transport properties of disordered and noisy chains, whereas translationally invariant case can be studied analytically in terms of a simple deterministic dynamical map.   the many - channel case was studied numerically by examining the statistical properties of scatterers that correspond to a certain type of transport of the chain i.e. ballistic or ( partially ) localised.   # 1#2 # 1#1| # 1|#1 # 1#2#1|#2 # 1#1 # 1#2 # 1#2#1|#2 # 1    # 1#2#3#4 # 1#2
the aim of this work is to study the imprints that different models for black hole ( bh ) and neutron star ( ns ) formation have on the galactic distribution of x - ray binaries ( xrbs ) which contain these objects.   we find that the root mean square of the height above the galactic plane of bh- and ns - xrbs is a powerful proxy to discriminate among different formation scenarios, and that binary evolution following the bh / ns formation does not significantly affect the galactic distributions of the binaries.   we find that a population model in which at least some bhs receive a ( relatively ) high natal kick fits the observed bh - xrbs best.   for the ns case, we find that a high nk distribution, consistent with the one derived from the measurement of pulsar proper motion, is the most preferable.   we also analyse the simple method we previously used to estimate the minimal peculiar velocity of an individual bh - xrb at birth.   we find that this method may be less reliable in the bulge of the galaxy for certain models of the galactic potential, but that our estimate is excellent for most of the bh - xrbs.       x - rays : binaries  supernovae : general  galaxy : dynamics  binaries : general  black hole physics   stars : neutron
i present a technique to remove the residual oh airglow emission from near infrared spectra.   historically, the need to subtract out the strong and variable oh airglow emission lines from 12.5micron  spectra has imposed severe restrictions on observational strategy. for integral field spectroscopy, where the field of view is limited, the standard technique is to observe blank sky frames at regular intervals.   however, even this does not usually provide sufficient compensation if individual exposure times are longer than 23minutes due to ( 1 ) changes in the absolute flux of the oh lines, ( 2 ) variations in flux among the individual oh lines, and ( 3 ) effects of instrumental flexure which can lead to ` p - cygni'type residuals.   the data processing method presented here takes all of these effects into account and serendipitously also improves background subtraction between the oh lines.   it allows one, in principle, to use sky frames taken hours or days previously so that observations can be performed in a quasi - stare mode. as a result, the observing efficiency ( i.e. fraction of time spent on a source ) at the telescope can be dramatically increased.       atmospheric effects  methods : data analysis  methods : observational  techniques : spectroscopic  infrared : general
we consider signal reconstruction from the norms of subspace components generalizing standard phase retrieval problems. in the deterministic setting,   a closed reconstruction formula is derived when the subspaces satisfy certain cubature conditions, that require at least a quadratic number of subspaces.   moreover, we address reconstruction under the erasure of a subset of the norms ; using the concepts of @xmath0-fusion frames and list decoding, we propose an algorithm that outputs a finite list of candidate signals, one of which is the correct one. in the random setting, we show that a set of subspaces chosen at random and of cardinality scaling linearly in the ambient dimension allows for exact reconstruction with high probability by solving the feasibility problem of a semidefinite program.
we investigated experimentally the ray - wave correspondence in organic microlasers of various triangular shapes.   triangular billiards are of interest since they are the simplest cases of polygonal billiards and the existence and properties of periodic orbits in triangles are not yet fully understood. the microlasers with symmetric shapes that were investigated exhibited states localized on simple periodic orbits, and their lasing characteristics like spectra and far - field distributions   could be well explained by the properties of the periodic orbits.   furthermore, asymmetric triangles that do not feature simple periodic orbits were studied.   their lasing properties were found to be more complicated and could not be explained by periodic orbits.
an important consequence of the discovery of giant magnetoresistance in metallic magnetic multilayers is a broad interest in spin dependent effects in electronic transport through magnetic nanostructures.   an example of such systems are tunnel junctions  single - barrier planar junctions or more complex ones. in this review   we present and discuss recent theoretical results on electron and spin transport through ferromagnetic mesoscopic junctions including two or more barriers.   such systems are also called ferromagnetic single - electron transistors.   we start from the situation when the central part of a device has the form of a magnetic ( or nonmagnetic ) metallic nanoparticle.   transport characteristics reveal then single - electron charging effects, including the coulomb staircase, coulomb blockade, and coulomb oscillations.   single - electron ferromagnetic transistors based on semiconductor quantum dots and large molecules ( especially carbon nanotubes ) are also considered.   the main emphasis is placed on the spin effects due to spin - dependent tunnelling through the barriers, which gives rise to spin accumulation and tunnel magnetoresistance.   spin effects also occur in the current - voltage characteristics, ( differential ) conductance, shot noise, and others.   transport characteristics in the two limiting situations of weak and strong coupling are of particular interest. in the former case   we distinguish between the sequential tunnelling and cotunnelling regimes. in the strong coupling regime   we concentrate on the kondo phenomenon, which in the case of transport through quantum dots or molecules leads to an enhanced conductance and to a pronounced zero - bias kondo peak in the differential conductance.
we investigate a set of discrete - time quantum search algorithms on the n - dimensional hypercube following a proposal by shenvi, kempe and whaley @xcite.   we show that there exists a whole class of quantum search algorithms in the symmetry reduced space which perform a search of a marked vertex in time of order @xmath0 where @xmath1, the number of vertices. in analogy to grover   s algorithm, the spatial search is effectively facilitated through a rotation in a two - level sub - space of the full hilbert space. in the hypercube  , these two - level systems are introduced through avoided crossings.   we give estimates on the quantum states forming the 2-level sub - spaces at the avoided crossings and derive improved estimates on the search times.
these short notes collect some thoughts about the way butcher  oemler - like and evolutionary studies are performed.   we emphasize the shortcomings of several overlooked technical ingredients in the above type of studies, with the hope of making a useful cookbook for future works.   we also briefly report new results of an ongoing butcher  oemler study at intermediate redshift.
an electronic phase separation model provides a natural explanation for a large variety of experimental results in the cuprates, including evidence for both stripes and larger domains, and a termination of the phase separation in the slightly overdoped regime, when the average hole density equals that on the charged stripes.   several models are presented for charged stripes, showing how density waves, superconductivity, and strong correlations compete with quantum size effects ( qses ) in narrow stripes.   the energy bands associated with the charged stripes develop in the middle of the mott gap, and the splitting of these bands can be understood by considering the qse on a single ladder.
we study a four - level atomic scheme interacting with four lasers in a closed - loop configuration with a @xmath0 ( diamond ) geometry.   we investigate the influence of the laser phases on the steady state.   we show that, depending on the phases and the decay characteristic, the system can exhibit a variety of behaviors, including population inversion and complete depletion of an atomic state.   we explain the phenomena in terms of multi - photon interference.   we compare our results with the phase - dependent phenomena in the double-@xmath1 scheme, as studied in [ korsunsky and kosachiov, phys.   rev a * 60 *, 4996 ( 1999 ) ].   this investigation may be useful for developing non - linear optical devices, and for the spectroscopy and laser - cooling of alkali - earth atoms.
photo - heating associated with reionisation and kinetic feedback from core - collapse supernovae have previously been shown to suppress the high - redshift cosmic star formation rate. here   we investigate the interplay between photo - heating and supernova feedback using a set of cosmological, smoothed particle hydrodynamics simulations.   we show that photo - heating and supernova feedback mutually amplify each other s ability to suppress the star formation rate.   our results demonstrate the importance of the simultaneous, non - independent inclusion of these two processes in models of galaxy formation to estimate the strength of the total negative feedback they exert.   they may therefore be of particular relevance to semi - analytic models in which the effects of photo - heating and supernova feedback are implicitly assumed to act independently of each other.       galaxies : high - redshift  galaxies : formation  galaxies : evolution
einstein s research manuscripts provide important insights into his exceptional creativity. at the same time, they can present difficulties for a publication in the documentary edition of the _ collected papers of albert einstein _ ( cpae ).   the problems are illustrated by discussing how some important examples of einstein s research manuscripts have been included in previous volumes of the cpae series : his scratch notebook from the years 19101914, his so - called zurich notebook from 1912, documenting his early search for a generally covariant theory of gravitation, and the einstein - besso manuscript from 1913, containing calculations of mercury s perihelion advance on the basis of the einstein - grossmann equations.   another category of research notes are small and disconnected `` back - of - an - envelope '' calculations.   a major challenge for future volumes of the cpae series are einstein s berlin and princeton research manuscripts on a unified field theory.   this batch of some 1700 undated manuscript pages presents a formidable challenge also for historians of science.   although the web provides new possibilities for the editorial task, such as the publication of facsimiles on the _ einstein archives online _ website, it is argued that a satisfactory solution of the editorial problems posed by these manuscripts depends on scholarly efforts to reconstruct and understand the content of einstein s manuscripts.
neural circuits often face the problem of classifying stimuli into discrete groups and making decisions based on such classifications. neurons of these circuits can be distinguished according to their correlations with different features of stimulus or response, which allows defining sensory or motor neuronal types. in this study   we define the third class of neurons, which is responsible for making decision.   we suggest two descriptions for contribution of units to decision making : first, as a spatial derivative of correlations between neural activity and the decision ; second, as an impact of variability in a given neuron on the response.   these two definitions are shown to be equivalent, when they can be compared.   we also suggest an experimental strategy for determining contributions to decision making, which uses electric stimulation with time- varying random current.
how does the tidal debris of minor galaxy mergers contribute to structures in spiral galaxies or in the intergalactic medium?   while major mergers are known to create structures such as tidal dwarf galaxies and star clusters within their tidal debris, less is known about minor mergers ( mass ratios between a dwarf galaxy and disk galaxy of less than one - third ) and their tidal debris.   this work surveys 6 nearby minor mergers using optical broad - band and @xmath0 narrow - band imaging to characterize star formation in their tidal debris.   young star clusters with ages less than the dynamical age of the tidal tails are found in all 6 mergers, indicating that the star clusters formed in situ. even if minor mergers contribute less tidal debris per interaction than major mergers, they are more common and possibly contribute structure to all types of galaxies and to the intergalactic medium throughout the history of the universe.
atomic diffusion may lead to heavy element accumulation inside stars in certain specific layers.   iron accumulation in the z - bump opacity region has been invoked by several authors to quantitatively account for abundance anomalies observed in some stars, or to account for stellar oscillations through the induced @xmath0-mechanism.   these authors however never took into account the fact that such an accumulation creates an inverse @xmath1-gradient, unstable for thermohaline convection. here, we present results for a - f stars, where abundance variations are computed with and without this process.   we show that iron accumulation is still present when thermohaline convection is taken into account, but much reduced compared to when this physical process is neglected.   the consequences of thermohaline convection for a - type stars as well as for other types of stars are presented.
we employ the method of the theory of open quantum systems to analyze spin relaxation and decoherence in semiconductors in the presence of a magnetic field.   we derive a set of bloch equations for electron spin with a fully microscopic determination of longitudinal and transverse relaxation times. electron scattering from optical and acoustic phonons and random impurities is taken into account.   we obtain explicit expressions for the spin relaxation times in terms of material constants and coupling strengths, exhibiting formal agreement with earlier treatments in the zero magnetic field limit with microscopic specification of their phenomenological parameters.
it has been estimated that the entire earth generates heat corresponding to about 40 tw ( equivalent to 10,000 nuclear power plants ) which is considered to originate mainly from the radioactive decay of elements like u, th and k, deposited in the crust and mantle of the earth.   radioactivity of these elements produce not only heat but also antineutrinos ( called geo - antineutrinos ) which can be observed by terrestrial detectors.   we investigate the possibility of discriminating among earth composition models predicting different total radiogenic heat generation, by observing such geo - antineutrinos at kamioka and gran sasso, assuming kamland and borexino ( type ) detectors, respectively, at these places. by simulating the future geo - antineutrino data as well as reactor antineutrino background contributions  , we try to establish to which extent we can discriminate among earth composition models for given exposures ( in units of kt@xmath0 yr ) at these two sites on our planet.   we use also information on neutrino mixing parameters coming from solar neutrino data as well as kamland reactor antineutrino data, in order to estimate the number of geo - antineutrino induced events.
i briefly review recent observations of regions forming low mass stars.   the discussion is cast in the form of seven questions that have been partially answered, or at least illuminated, by new data.   these are the following : where do stars form in molecular clouds ; what determines the imf ; how long do the steps of the process take ; how efficient is star formation ; do any theories explain the data ; how are the star and disk built over time ; and what chemical changes accompany star and planet formation.   i close with a summary and list of open questions.
we use the kerr - schild type teukolsky equation ( horizon penetrating ) to evolve binary black hole initial data as proposed by bishop _   et al. _ in the close limit.   our results are in agreement with those recently obtained by sarbach _   et al. _ from the zerilli equation evolution of the same initial data.
we present high - resolution mid - infrared observations of the nearby late - type young binary system hen 3 - 600.   the binary, at a distance of @xmath0 50 pc, could be a member of the tw hydrae association, the nearest known group of young stars, with an age of a few million years.   our images make it possible for the first time to determine which star in the pair, separated by 1.4 , harbors the mid - infrared excess detected by iras. in the near - infrared, where the radiation is primarily photospheric, hen 3 - 600a ( m3 ) and hen 3 - 600b ( m3.5 ) have a flux ratio of 1.6. at 4.8@xmath1 m, 10.8@xmath1 m, and 18.2@xmath1 m,   the primary becomes increasingly dominant over the secondary, suggesting that most of the circumstellar dust in the system resides around hen 3 - 600a.   comparison of the spectral energy distribution ( sed ) of hen 3 - 600a to the median sed of classical t tauri stars suggests that its disk may be truncated by the secondary and provides tentative evidence for a central disk hole.   the distribution of dust in the hen 3 - 600 system may provide important clues to the formation and evolution of protoplanetary disks in close binaries.    0 _
using a sample of galaxy groups selected from the sloan digital sky survey data release 7 ( sdss dr7 ), we examine the alignment between the orientation of galaxies and their surrounding large scale structure in the context of the cosmic web.   the latter is quantified using the large - scale tidal field, reconstructed from the data using galaxy groups above a certain mass threshold.   we find that the major axes of galaxies in filaments tend to be preferentially aligned with the directions of the filaments, while galaxies in sheets have their major axes preferentially aligned parallel to the plane of the sheets.   the strength of this alignment signal is strongest for red, central galaxies, and in good agreement with that of dark matter halos in n - body simulations.   this suggests that red, central galaxies are well aligned with their host halos, in quantitative agreement with previous studies based on the spatial distribution of satellite galaxies.   there is a luminosity and mass dependence that brighter and more massive galaxies in filaments and sheets have stronger alignment signals.   we also find that the orientation of galaxies is aligned with the eigenvector associated with the smallest eigenvalue of the tidal tensor.   these observational results indicate that galaxy formation is affected by large - scale environments, and strongly suggests that galaxies are aligned with each other over scales comparable to those of sheets and filaments in the cosmic web.
we present a study of the optical ( bri ) and near - infrared ( jhk ) luminosity fuctions ( lfs ) of the gems sample of 60 nearby groups of galaxies between @xmath0, with our optical ccd photometry and near - ir photometry from the 2mass survey.   the lfs in all filters show a depletion of galaxies of intermediate luminosity, two magnitudes fainter than @xmath1, within @xmath2 from the centres of x - ray faint groups.   this feature is not as pronounced in x - ray bright gropus, and vanishes when lfs are found out to @xmath3, even in the x - ray dim groups.   we argue that this feature arises due to the enhanced merging of intermediate - mass galaxies in the dynamically sluggish environment of low velocity - dispersion groups, indicating that merging is important in galaxy evolution even at @xmath4.
in this paper we present new high resolution vla 1.4 ghz radio continuum observations of five fir bright co - rich early - type galaxies and two dwarf early - type galaxies. the position on the radio - fir correlation combined with striking agreements in morphology between high resolution co and radio maps   show that the radio continuum is associated with star formation in at least four of the eight galaxies.   the average star formation rate for the sample galaxies detected in radio is @xmath02   m@xmath1 year@xmath2.   there is no evidence of a luminous agn in any of our sample galaxies.   we estimate toomre @xmath3 values and find that the gas disks may well be gravitationally unstable, consistent with the above evidence for star formation activity.   the radio continuum emission thus corroborates other recent suggestions that star formation in early type galaxies may not be uncommon.
in this paper we perform a detailed study of the masses and mixing of the single charmed scalar tetraquarks : @xmath0. we also give a systematic analysis of these tetraquark states by weight diagrams, quantum numbers and flavor wave functions.   tetraquark masses are calculated using four different fits.   the following su(3)@xmath1 representations are discussed : @xmath2, @xmath3, @xmath4 and @xmath5.   we use the flavor - spin glozman - riska interaction hamiltonian with su(3 ) flavor symmetry breaking.   there are 27 different tetraquarks composed of a charm quark @xmath6 and of the three light flavors @xmath7 : 11 cryptoexotic ( 3 d@xmath8, 4 d@xmath9, 4 d@xmath10 ) and 16 explicit exotic states.   we discuss d@xmath11 and its isospin partners in the same multiplet, as well as all the other four - quark states.   some explicit exotic states appear in the spectrum with the same masses as d@xmath8(2632 ) in @xmath2 and with the same masses as d@xmath8(2317 ) in @xmath4 representation, which confirm the tetraquark nature of these states.
a series of experiments measuring high - energy cosmic rays have recently reported strong indications for the existence of an excess of high - energy electrons and positrons.   if interpreted in terms of the decay of dark matter particles, the pamela measurements of the positron fraction and the fermi lat measurements of the total electron - plus - positron flux restrict the possible decaying dark matter scenarios to a few cases. analyzing different decay channels in a model - independent manner, and adopting a conventional diffusive reacceleration model for the background fluxes of electrons and positrons, we identify some promising scenarios of dark matter decay and calculate the predictions for the diffuse extragalactic gamma - ray flux, including the contributions from inverse compton scattering with the interstellar radiation field.
it has long been thought that the pulsed x - ray properties of rotation - powered pulsars are stable on long time scales. however, long - term, systematic studies of individual sources have been lacking.   furthermore, dramatic x - ray variability has now been observed from two pulsars having inferred sub - critical dipole magnetic fields.   here we present an analysis of the long - term pulsed x - ray properties of the young, energetic pulsar psr  b1509@xmath058  using data from the _ rossi x - ray timing explorer_. we measured the 250kev pulsed flux for 14.7yr of x - ray observations and found that it is consistent with being constant on all relevant time scales, and place a 3@xmath1 upper limit on day - to - week variability of @xmath228%.   in addition, we searched for magnetar - like x - ray bursts in all observations and found none, which we use to constrain the measurable burst rate to less than one per 750ks of observations.   we also searched for variability in the pulse profile and found that it is consistent with being stable on time scales of days to decades.   this supports the hypothesis that x - ray properties of rotation - powered x - ray pulsars can be stable on decade - long time scales.   in addition, we extend the existing timing solution by 7.1yr to a total of 28.4yr and report updated values of the braking index, @xmath3 and the second braking index, @xmath4.
this paper describes sufficient conditions to ensure the correct ergodicity of the adaptive metropolis ( am ) algorithm of haario, saksman and tamminen  for target distributions with a noncompact support. the conditions ensuring a strong law of large numbers require that the tails of the target density decay super - exponentially and have regular contours.   the result is based on the ergodicity of an auxiliary process that is sequentially constrained to feasible adaptation sets, independent estimates of the growth rate of the am chain and the corresponding geometric drift constants.   the ergodicity result of the constrained process is obtained through a modification of the approach due to andrieu and moulines [ _ ann.   appl.   probab. _   * 16 * ( 2006 ) 14621505 ].    and   .
the dynamical model on 3 + 1 dimensional space - time admitting soliton solutions is discussed.   the proposal soliton is localized in the vicinity of a closed contour, which could be linked and/or knotted.   the topological charge is hopf invariant.   some applications in realistic physical systems are indicated.   4.5 mm    * 2000 mathematics subject classification : * 35q51, 35s35, 65c20, 81v25.    * keywords and phrases : * soliton, knot, hopf invariant.
franson s paradigm for nonlocal dispersion cancellation [ j. d. franson, phys.   rev.   a * 45, * 3126 ( 1992 ) ] is studied using two kinds of jointly gaussian - state signal and reference beams with phase - sensitive cross correlations.   the first joint signal - reference state is nonclassical, with a phase - sensitive cross correlation that is at the ultimate quantum - mechanical limit.   it models the outputs obtained from continuous - wave spontaneous parametric downconversion.   the second joint signal - reference state is classical  it has a proper @xmath0 representation  with a phase - sensitive cross correlation that is at the limit set by classical physics. using these states   we show that a version of franson s nonlocal dispersion cancellation configuration has essentially identical quantum and classical explanations _ except  for the contrast obtained, which is much higher in the quantum case than it is in the classical case.   this work bears on franson s recent paper  ], which asserts that there is no classical explanation for all the features seen in quantum nonlocal dispersion cancellation. _
we perform a computational study of a variant of the `` train '' model for earthquakes , where we assume a static friction that is a stochastic function of position rather than being velocity dependent.   the model consists of an array of blocks coupled by springs, with the forces between neighbouring blocks balanced by static friction.   we calculate the probability, @xmath0, of the occurrence of avalanches with a size @xmath1 or greater, finding that our results are consistent with the phenomenology and also with previous models which exhibit a power law over a wide range.   we show that the train model may be mapped onto a stochastic sandpile model and study a variant of the latter for non - spherical grains.   we show that, in this case, the model has critical behaviour only for grains with large aspect ratio, as was already shown in experiments with real ricepiles.   we also demonstrate a way to introduce randomness in a physically motivated manner into the model.
the report of an iupac task group, formed in 2011 on `` intensities and line shapes in high - resolution spectra of water isotopologues from experiment and theory '' ( project no.   2011 - 022 - 2 - 100 ), on line profiles of isolated high - resolution rotational - vibrational transitions perturbed by neutral gas - phase molecules is presented.   the well - documented inadequacies of the voigt profile ( vp ), used almost universally by databases and radiative - transfer codes, to represent pressure effects and doppler broadening in isolated vibrational - rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line - profile models.   these models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity.   the task group recommends that the partially correlated quadratic - speed - dependent hard - collision profile should be adopted as the appropriate model for high - resolution spectroscopy. for simplicity   this should be called the hartmann  tran profile ( htp ).   the htp is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the voigt profile, under certain simplifying assumptions.
we study the faraday rotation measure ( rm ) due to the galactic magnetic field ( gmf ) toward high galactic latitudes.   the rm arises from the global, regular component as well as from the turbulent, random component of the gmf.   we model the former based on observations and the latter using the data of magnetohydrodynamic turbulence simulations. for a large number of different gmf models, we produce mock rm maps around the galactic poles and calculate various statistical quantities with the rm maps.   we find that the observed medians of rms toward the north and south galactic poles, @xmath0 and @xmath1, are difficult to explain with any of our many alternate gmf models.   the standard deviation of observed rms, @xmath2, is clearly larger than that of simulated rms.   the second - order structure function of observed rms is substantially larger than that of simulated rms, especially at small angular scales.   we discuss other possible contributions to rm toward high galactic latitudes. besides observational errors and the intrinsic rm of background radio sources against which   rm is observed, we suggest that the rm due to the intergalactic magnetic field may account for a substantial fraction of the observed rm. finally we note that reproducing the observed medians may require additional components or / and structures of the gmf that are not present in our models.
starting with a model hamiltonian, we study using the uniform expansion method conformational behavior of polyelectrolytes in the presence and absence of salt  . the uniform expansion method yields all the important local length scales in the polyelectrolyte : the electrostatic blob size at large fraction of charges, the thermal blob size at low fraction of charges and the sizes of pearls ( beads ) and necklaces ( strings ) at intermediate fraction of charges. in the presence of salt,   the electrostatic blob size depends on the ionic strength and increases with the increase in the salt concentration.   we determine the salt concentration at which the pearl necklace intermediates dissolve and the nature of the transition changes from discontinuous to continuous.   this critical salt concentration corresponds to the length scale where the debye screening length is of the order of the necklace length.
in this paper, a transmission strategy of fountain codes over cooperative relay networks is proposed. when more than one relay nodes are available, we apply network coding to fountain - coded packets. by doing this,   partial information is made available to the destination node about the upcoming message block.   it is therefore able to reduce the required number of transmissions over erasure channels, hence increasing the effective throughput.   its application to wireless channels with rayleigh fading and awgn noise is also analysed, whereby the role of analogue network coding and optimal weight selection is demonstrated.
we have used the parkes multibeam system and the sloan digital sky survey ( sdss ) to assemble a sample of 195 galaxies selected originally from their signature to avoid biases against unevolved or low surface brightness objects. for each source 9   intrinsic properties are measured homogeneously, as well as inclination and an optical spectrum.   the sample, which should be almost entirely free of either misidentification or confusion, includes a wide diversity of galaxies ranging from inchoate, low surface brightness dwarfs to giant spirals. despite this diversity   there are 5 clear correlations among their properties.   they include a common dynamical mass - to - light ratio within their optical radii, a correlation between surface - brightness and luminosity and a common surface - density.   such correlation should provide strong constrains on models of galaxy formation and evolution.       galaxies : fundamental parameters  galaxies : evolution  galaxies : general  galaxies : structure  galaxies : peculiar.
detector devis is tpc in the magnetic field.   it is dedicated to the investigation of the double - beta decay of xe.   setup sensitivity was estimated in the series of measurements with xe with natural isotopes composition.   detector allows measuring two - neutrino double - beta decay of @xmath0xe with half - life less than @xmath1 years.   institute for theoretical and experimental physics
over the last 15 years, around a hundred very young stars have been observed in the central parsec of our galaxy.   while the presence of young stars forming one or two stellar disks at @xmath0pc from the supermassive black hole ( smbh ) can be understood through star formation in accretion disks, the origin of the s stars observed a factor of 10 closer to the smbh has remained a major puzzle.   here we show the s stars to be a natural consequence of dynamical interaction of two stellar disks at larger radii. due to precession and kozai interaction, individual stars   achieve extremely high eccentricities at random orientation.   stellar binaries on such eccentric orbits are disrupted due to close passages near the smbh, leaving behind a single s star on a much tighter orbit.   the remaining star may be ejected from the vicinity of the smbh, thus simultaneously providing an explanation for the observed hypervelocity stars in the milky way halo.
by assuming the existence of the sequential fourth generation to the minimal supersymmetric standard model ( mssm ), we study the possibility of a strongly first - order electroweak phase transition. we find that there is a parameter region of the mssm where the electroweak phase transition is strongly first order. in that parameter region  , the mass of the lighter scalar higgs boson is calculated to be above the experimental lower bound, and the scalar quarks of the third and the fourth generations are heavier than the corresponding quarks.
we investigate an open @xmath0 spin @xmath1 chain driven out of equilibrium by coupling with boundary reservoirs targeting different spin orientations in @xmath2 plane.   symmetries of the model are revealed which appear to be different for spin chains of odd and even sizes. as a result  , spin current is found to alternate with chain length, ruling out the possibility of ballistic transport.   heat transport is switched off completely by virtue of another global symmetry.   further, we investigate the model numerically and analytically. at strong coupling,   we find exact nonequilibrium steady state using a perturbation theory.   the state is determined by solving secular conditions which guarantee self - consistency of the perturbative expansion.   we find nontrivial dependence of the magnetization current on the spin chain anisotropy @xmath3 in the critical region @xmath4, and a phenomenon of tripling of the twisting angle along the chain for narrow lacunes of @xmath3.
the rapid tev @xmath0ray variability detected in the well - known nearby radio galaxy m87 implies an extremely compact emission region ( @xmath1 schwarzschild radii ) near the horizon of the supermassive black hole in the galactic center.   tev photons are affected by dilution due to interaction with the radiation field of the advection - dominated accretion flow ( adaf ) around the black hole, and can thus be used to probe the innermost regions around the black hole.   we calculate the optical depth of the adaf radiation field to the tev photons and find it strongly depends on the spin of the black hole.   we find that transparent radii of 10 tev photons are of @xmath2 and @xmath3 for the maximally rotating and non - rotating black holes, respectively. with the observations,   the calculated transparent radii strongly suggest the black hole is spinning fast in the galaxy.   tev photons could be used as a powerful diagnostic for estimating black hole spins in galaxies in the future.
intermediate energy scale physics plays a very important role in non - equilibrium dynamics of quasi - low dimensional cold atom systems. in this article   we obtain the universal scaling relations for the generalized reflection coefficient, i.e., the fraction of atoms scattered out of the initial state, at intermediate energy scales, scales larger than the trap frequency but much smaller than the effective range of the potential, for one and two dimensional harmonically confined geometries.   whenever the energy of the cold atoms is commensurate with a transverse energy level, it is shown that the system becomes non - interacting. when the difference between the energy of the cold atoms and the given transverse energy level, @xmath0, is small compared to the trap frequency, @xmath1, i.e. when @xmath2, the reflection coefficient has the universal scaling form @xmath3, where @xmath4 is a constant.   the power law behaviour and prefactor @xmath4 appear regardless of the three dimensional scattering length and initial conditions.
we develop a simple, time - dependent comptonization model to probe the origins of spectral variability in accreting neutron star systems. in the model,   soft `` seed photons '' are injected into a corona of hot electrons, where they are compton upscattered before escaping as hard x - rays.   the model describes how the hard x - ray spectrum varies when the properties of either the soft photon source or the comptonizing medium undergo small oscillations.   observations of the resulting spectral modulations can determine whether the variability is due to ( i )  oscillations in the injection of seed photons, ( ii )  oscillations in the coronal electron density, or ( iii )  oscillations in the coronal energy dissipation rate.   identifying the origin of spectral variability should help clarify how the corona operates and its relation to the accretion disk.   it will also help in finding the mechanisms underlying the various quasi - periodic oscillations ( qpo ) observed in the x - ray outputs of many accreting neutron star and black hole systems. as a sample application of our model  , we analyze a kilohertz qpo observed in the atoll source 4u  1608 - 52.   we find that the qpo is driven predominantly by an oscillation in the electron density of the comptonizing gas.     * = " 002a
the synchronized magnetization dynamics in ferromagnets on a nonmagnetic heavy metal caused by the spin hall effect is investigated theoretically.   the direct and inverse spin hall effects near the ferromagnetic / nonmagnetic interface generate longitudinal and transverse electric currents.   the phenomenon is known as the spin hall magnetoresistance effect, whose magnitude depends on the magnetization direction in the ferromagnet due to the spin transfer effect. when another ferromagnet is placed onto the same nonmagnet, these currents are again converted to the spin current by the spin hall effect and excite the spin torque to this additional ferromagnet, resulting in the excitation of the coupled motions of the magnetizations.   the in - phase or antiphase synchronization of the magnetization oscillations, depending on the value of the gilbert damping constant and the field - like torque strength, is found in the transverse geometry by solving the landau - lifshitz - gilbert equation numerically. on the other hand, in addition to these synchronizations,   the synchronization having a phase difference of a quarter of a period is also found in the longitudinal geometry. the analytical theory clarifying the relation among the current, frequency, and phase difference   is also developed, where it is shown that the phase differences observed in the numerical simulations correspond to that giving the fixed points of the energy supplied by the coupling torque.
we present results from an 87-ks _ suzaku _ observation of the canonical low - excitation radio galaxy ( lerg ) ngc6251.   we have previously suggested that lergs violate conventional agn unification schemes : they may lack an obscuring torus and are likely to accrete in a radiatively inefficient manner, with almost all of the energy released by the accretion process being channeled into powerful jets.   we model the 0.520 kev _ suzaku _ spectrum with a single power law of photon index @xmath0, together with two collisionally ionized plasma models whose parameters are consistent with the known galaxy- and group - scale thermal emission.   our observations confirm that there are no signatures of obscured, accretion - related x - ray emission in ngc 6251, and we show that the luminosity of any such component must be substantially sub - eddington in nature.
we present a detailed study of the magnetic structure and spin waves in the fe jarosite compound @xmath0 for the most general hamiltonian involving one- and two - spin interactions which are allowed by symmetry.   we compare the calculated spin - wave spectrum with the recent neutron scattering data of matan _   et al. _ for various model hamiltonians which include,   in addition to isotropic heisenberg exchange interactions between nearest ( @xmath1 ) and next - nearest ( @xmath2 ) neighbors, single ion anisotropy and dzyaloshinskii - moriya ( dm ) interactions. we concluded that dm interactions are the dominant anisotropic interaction, which not only fits all the splittings in the spin - wave spectrum but also reproduces the small canting of the spins out of the kagom plane. a brief discussion of how representation theory restricts the allowed magnetic structure is also given.
we present the timing analysis of the four archived xmm-_newton _ observations of pg 1211 + 143.   the source is well - known for its spectral complexity, comprising a strong soft - excess and different absorption systems.   soft energy band ( 0.3 - 0.7 kev ) lags are detected over all the four observations, in the frequency range @xmath0 hz, where hard lags, similar to those observed in black hole x - ray binaries, are usually detected in smaller mass agn. the lag magnitude is energy - dependent, showing two distinct trends apparently connectable to the two flux levels at which the source is observed.   the results are discussed in the context of disk- and/or corona - reprocessing scenarios, and of disk wind models.   similarities with the high - frequency negative lag of 1h 0707 - 495 are highlighted, and, if confirmed, they would support the hypothesis that the lag in pg 1211 + 143 represents the signature of the same underlying mechanism, whose temporal characteristics scale with the mass of the central object.   galaxies : active, galaxies : quasars : individual : pg 1211 + 143, x - rays : galaxies
rate of period change @xmath0 for a cepheid is shown to be a parameter that is capable of indicating the instability strip crossing mode for individual objects, and, in conjunction with light amplitude, likely location within the instability strip.   observed rates of period change in over 200 milky way cepheids are demonstrated to be in general agreement with predictions from stellar evolutionary models, although the sample also displays features that are inconsistent with some published models and indicative of the importance of additional factors not fully incorporated in models to date.
a light reflection technique is used to measure quantitatively the surface elevation of faraday waves.   the performed measurements cover a wide parameter range of driving frequencies and sample viscosities. in the capillary wave regime   the bifurcation diagrams exhibit a frequency independent scaling proportional to the wavelength.   we also provide numerical simulations of the full navier - stokes equations, which are in quantitative agreement up to supercritical drive amplitudes of @xmath0.   the validity of an existing perturbation analysis is found to be limited to @xmath1.
the cross sections of the reaction @xmath0 for @xmath1 or @xmath2 mesons and @xmath3 or @xmath4 hyperons are calculated within the boson exchange model including pion and kaon exchange diagrams.   we analyze the dependence of the results on the accuracy of the input @xmath5 amplitude. by fixing the @xmath6 coupling constant and the cut - off parameter @xmath7 at the @xmath8 vertex we calculate the contribution from the kaon exchange diagram and obtain the ratio of the @xmath9 and @xmath10 coupling constants by a fit to the experimental data.   this ratio is in a good agreement with the @xmath11 prediction.   our calculated total cross sections for the different reaction channels are fitted by simple expressions and compared with other parameterizations used in the literature.   furthermore, the gross features of the production cross section close to threshold are discussed.   = -10 mm = -40pt    ifuj, ifj-1787/ph, ugi-98 - 6
we examine the dynamics of an age - structured population model in which the life expectancy of an offspring may be mutated with respect to that of the parent.   while the total population of the system always reaches a steady state, the fitness and age characteristics exhibit counter - intuitive behavior as a function of the mutational bias. by analytical and numerical study of the underlying rate equations,   we show that if deleterious mutations are favored, the average fitness of the population reaches a steady state, while the average population age is a _ decreasing _ function of the overall fitness.   when advantageous mutations are favored, the average population fitness grows linearly with time @xmath0, while the average age is independent of fitness. for no mutational bias  , the average fitness grows as @xmath1.    2
in this article we discuss some aspects of solar physics from the standpoint of the so - called chameleon fields ( i.e. quantum fields, typically scalar, where the mass is an increasing function of the matter density of the environment ).   firstly, we analyze the effects of a chameleon - induced deviation from standard gravity just below the surface of the sun.   in particular, we develop solar models which take into account the presence of the chameleon and we show that they are inconsistent with the helioseismic data.   this inconsistency presents itself not only with the typical chameleon set - up discussed in the literature ( where the mass scale of the potential is fine - tuned to the mev ), but also if we remove the fine - tuning on the scale of the potential.   however, if we modify standard gravity only in a shell of thickness @xmath0 just below the solar surface, the model is basically indistinguishable from a standard solar model.   secondly, we point out that, in a model recently considered in the literature ( we call this model  modified fujii s model  ), a conceivable interpretation of the solar oscillations is given by quantum vacuum fluctuations of a chameleon.
an approach to the model - independent searching for the @xmath0 gauge boson as a virtual state in scattering processes is developed.   it accounts for as a basic requirement the renormalizability of underlying unspecified in other respects model.   this results in a set of relations between low energy couplings of @xmath0 to fermions that reduces in an essential way the number of parameters to be fitted in experiments. on this ground   the observables which uniquely pick out the @xmath0 boson in leptonic processes are introduced and the data of lep experiments analyzed. the @xmath0 couplings to leptons and quarks are estimated at 95% confidence level.   these estimates may serve as a guide for experiments at the tevatron and/or lhc.   a comparison with other approaches and results is given.
many unsolved fundamental problems in quantum mechanics originated on the boundary between the classical and quantum worlds. quantum correlation, however, gives a signature of such boundary.   an essential feature of genuine quantum correlation is the simultaneous existence of correlation in complementary bases.   we reveal this feature of quantum correlation by defining measures based on invariance under a basis change. for a bipartite quantum state,   the classical correlation is the maximal correlation present in a certain optimum basis, while the quantum correlation is characterized as a series of residual correlations in the mutually unbiased bases.   compared with other approaches to quantify quantum correlation, our approach gives information - theoretical measures that directly reflect the essential feature of quantum correlation.   classical correlation that exists in a certain basis vanishes in any complementary bases, while genuine quantum correlation exists simultaneously in the complementary bases.   this property of quantum correlation enables a peculiar feature called the  spooky action at a distance " by einstein. here,   we present a natural way to quantify the  spooky action at a distance ", and quantitatively reveal the essential mystery of genuine quantum correlation : the simultaneous existence in complementary bases.
surface reconstructions on the polar zno(0001 ) surface are investigated using empirical potential models.   several possible reconstructions based around triangular motifs are investigated.   the quenching of the dipole moment in the material dominates the energetics of the surface patterns so that no one particular size of surface triangular island or pit is strongly favoured.   we employ monte carlo simulations to explore which patterns emerge from a high temperature quench and during deposition of additional zno monolayers.   the simulations show that a range of triangular islands and pits evolve in competition with one another.   the surface patterns we discover are qualitatively similar to those observed experimentally.
we study hadron properties near the deconfining transition in the finite temperature lattice qcd.   this paper focus on the heavy quarkonium states, such as @xmath0 meson.   we compare the meson correlators above and below @xmath1 and discuss the possibility of the @xmath2 bound state by observing the wave function.
we study the temperature dependent dynamical processes of a si@xmath0h@xmath1 cluster and obtain a blue shift of the si - si vibrational modes with transverse acoustic character and a red shift of the other vibrational modes with increasing temperature.   we link this behavior to the bond length expansion and the varying sign of the grneisen parameter.   we further present a computational approach able to extract the vibron - vibron coupling strength in clusters or molecules.   our approach is based on _ ab initio _ born - oppenheimer molecular dynamics and a projection formalism able to deliver the individual vibron occupation numbers. from the fourier   transform of the vibron energy autocorrelation function we obtain the coupling strength of each vibron to the most strongly coupled vibronic states.   we find vibron - vibron coupling strength up to 2.5 thz with a moderate increase of about 5% when increasing the temperature from 50 to 150 k.
we analyse rxte / pca x - ray spectra of the binary x - ray pulsar her x-1/hz her during short high state and one binary orbit in the preceding low state, just before short high turn - on.   the spectrum is well described by two continuum components ( absorbed and unabsorbed ).   the resulting spectral parameters are modulated with orbital phase. during low state   a significant component of the flux, and its spectrum, is consistent with x - ray reflection off the face of the companion star hz her.   this component has a significantly harder x - ray spectrum than the rest of the flux from the her x-1 system.   a second component in low state is consistent with emission from the accretion disk corona. during short high   a third strong component is present with a softer spectrum, which is associated with the neutron star and accretion disk. due to this direct emission from the neutron star and accretion disk,   the reflected emission is less clear, however parameters and fluxes modulations during short high state indicate its presence. in low state,   the hard x - ray flux ( @xmath0 @xmath1 @xmath2 ) peaks at orbital phase @xmath3 0.55, which is expected from a simple model of atmospheric reflection from the companion star.   the offset indicates an asymmetry in the x - ray illumination of the companion, which could be due to shadowing of the the inner face of hz her by the accretion disk and/or stream.
homoepitaxy of w(110 ) and mo(110 ) is performed in a kinetically - limited regime to yield a nanotemplate in the form of a uniaxial array of hills and grooves aligned along the  direction.   the topography and organization of the grooves were studied with rheed and stm.   the nanofacets, of type \{210 }, are tilted @xmath0 away from ( 110 ).   the lateral period could be varied from 4 to by tuning the deposition temperature.   magnetic nanowires were formed in the grooves by deposition of fe at @xmath1c on such templates.   fe / w wires display an easy axis along  and a mean blocking temperature @xmath2{k}$ ].   epitaxial growth, iron, tungsten, molybdenum, nanowires, self - organization, nanotemplate, rheed patterns, magnetic anisotropy
there is strong evidence that the period - luminosity ( pl ) relation for the large magellanic cloud ( lmc ) cepheids shows a break at a period around 10 days. since the lmc pl relation   is extensively used in distance scale studies, the non - linearity of the lmc pl relation may affect the results based on this lmc calibrated relation. in this paper   we show that this problem can be remedied by using the wesenheit function in obtaining cepheid distances.   this is because the wesenheit function is linear although recent data suggests that the pl and the period - colour ( pc ) relations that make up the wesenheit function are not.   we test the linearity of the wesenheit function and find strong evidence that the lmc wesenheit function is indeed linear.   this is because the non - linearity of the pl and pc relations cancel out when the wesenheit function is constructed.   we discuss this result in the context of distance scale applications.   we also compare the distance moduli obtained from @xmath0 ( equivalent to wesenheit functions ) constructed with the linear and the broken lmc pl relations, and find that the typical difference in distance moduli is @xmath1mag.   hence, the broken lmc pl relation does not seriously affect current distance scale applications.   we also discuss the random error calculated with equation @xmath0, and show that there is a correlation term that exists from the calculation of the random error  . the calculated random error will be larger if this correlation term is ignored.   cepheids  distance scale
measurements of the vertical velocity of ice crystals using a @xmath0 doppler lidar are described.   the statistics from a continuous sample of stratiform ice clouds over 17 months are analysed : the distribution of velocity varies strongly with temperature, with average doppler velocities of @xmath1 at @xmath2 increasing to @xmath3 at @xmath4 presumably due to particle growth and broadening of the size spectrum.   we examine the likely influence of small crystals less than @xmath5 by forward modelling their effect on the area - weighted fall speed, and comparing the results to the lidar observations.   the comparison strongly suggests that the concentration of these small crystals in most ice clouds is much lower than measured in - situ by cloud droplet probes.   the discrepancy is attributed to shattering of large crystals on the probe inlet, and we argue that these numerous small particles should not be included in numerical weather and climate model parametrizations.
we study the interaction of strong femtosecond laser pulses with the c@xmath0 molecule employing time - dependent density functional theory with the ionic background treated in a jellium approximation.   the laser intensities considered are below the threshold of strong fragmentation but too high for perturbative treatments such as linear response.   the nonlinear response of the model to excitations by short pulses of frequencies up to 45ev is presented and analyzed with the help of kohn - sham orbital resolved dipole spectra. in femtosecond laser pulses of 800 nm wavelength ionization   is found to occur multiphoton - like rather than via excitation of a `` giant '' resonance.   pacs numbers : 36.40.-c, 33.80.rv, 31.15.ew    # 1#2    # 1( )    # 1 # 1    # 1    # 1#2#3#4    (    cc # 1 & # 2 + # 3 & # 4    )    # 1#2    (    c # 1 + # 2    )    # 1#2 # 1#1 # 1| # 1 # 1#2#1 # 2    # 1#1 ^2
self - assembly hierarchical solid surfaces are very interesting for wetting phenomena, as observed in a variety of natural and artificial surfaces. here  , we report single - walled ( swcnt ) and multi - walled carbon nanotube ( mwcnt ) thin films realized by a simple, rapid, reproducible, and inexpensive filtration process from an aqueous dispersion, then deposited by dry - transfer printing method on glass, at room temperature.   furthermore, the investigation of carbon nanotube films by scanning electron microscopy ( sem ) reveals the multi - scale hierarchical morphology of self - assembly carbon nanotube random networks.   moreover, contact angle measurements show that hierarchical swcnt / mwcnt composite surfaces exhibit a higher hydrophobic behavior ( up to 137@xmath0 ) than bare swcnt ( 110@xmath0 ) and mwcnt ( 97@xmath0 ) coatings, thereby confirming the enhancement produced by the surface hierarchical morphology.
we develop a classification algorithm for estimating posterior distributions from positive - unlabeled data, that is robust to noise in the positive labels and effective for high - dimensional data. in recent years  , several algorithms have been proposed to learn from positive - unlabeled data ; however, many of these contributions remain theoretical, performing poorly on real high - dimensional data that is typically contaminated with noise.   we build on this previous work to develop two practical classification algorithms that explicitly model the noise in the positive labels and utilize univariate transforms built on discriminative classifiers.   we prove that these univariate transforms preserve the class prior, enabling estimation in the univariate space and avoiding kernel density estimation for high - dimensional data.   the theoretical development and parametric and nonparametric algorithms proposed here constitute an important step towards wide - spread use of robust classification algorithms for positive - unlabeled data.   = 1
the x - ray binary cygnus x-2 ( cyg x-2 ) has recently been shown to contain a secondary that is much more luminous and hotter than is appropriate for a low - mass subgiant.   we present detailed binary - evolution calculations which demonstrate that the present evolutionary state of cyg x-2 can be understood if the secondary had an initial mass of around @xmath0 and started to transfer mass near the end of its main - sequence phase ( or, somewhat less likely, just after leaving the main sequence ).   most of the mass of the secondary must have been ejected from the system during an earlier rapid mass - transfer phase. in the present phase,   the secondary has a mass of around @xmath1 with a non - degenerate helium core.   it is burning hydrogen in a shell, and mass transfer is driven by the advancement of the burning shell.   cyg x-2 therefore is related to a previously little studied class of intermediate - mass x - ray binaries ( imxbs ).   we suggest that perhaps a significant fraction of x - ray binaries presently classified as low - mass x - ray binaries may be descendants of imxbs and discuss some of the implications.
we explore the physics of a gas of particles interacting with a condensate that spontaneously breaks lorentz invariance.   the equation of state of this gas varies from @xmath0 to less than @xmath1 and can lead to the observed cosmic acceleration without requiring a vacuum energy.   the particles are always stable. in our particular class of models   these particles are fermions with a chiral coupling to the condensate.   they may behave as relativistic matter at early times, produce a brief period where they dominate the expansion with @xmath2 today, and behave as matter at late time.   there are no small parameters in our models, which generically lead to dark energy clustering and, depending on the choice of parameters, smoothing of small scale power.
this review covers four current questions in the behavior of the atomic and molecular interstellar medium.   these include whether the atomic gas originates primarily in cold streams or hot flows onto galaxies ; what the filling factor of cold gas actually is in galactic regions observationally determined to be completely molecular ; whether molecular hydrogen determines or merely traces star formation ; and whether gravity or turbulence drives the dynamical motions observed in interstellar clouds, with implications on their star formation properties.
we study a random magnetic resonance force microscopy ( mrfm ) signal caused by the thermal vibrations of high frequency cantilever modes in the oscillating cantilever - driven adiabatic reversals ( oscar ) technique.   we show that the regular mrfm signal with a characteristic decay time, @xmath0, is followed by a non - dissipative random signal with a characteristic time @xmath1.   we present the estimates for the values of @xmath0 and @xmath1.   we argue that this random mrfm signal can be used for spin detection.   it has a `` signature '' of a sharp peak in its fourier spectrum.
the search for new interactions of neutrinos beyond those of the standard model may help to elucidate the mechanism responsible for neutrino masses. here   we combine existing accelerator neutrino data with restrictions coming from a recent atmospheric neutrino data analysis in order to lift parameter degeneracies and improve limits on new interactions of muon neutrinos with quarks.   in particular we re - consider the results of the nutev experiment in view of a new evaluation of its systematic uncertainties.   we find that, although constraints for muon neutrinos are better than those applicable to tau or electron neutrinos, they lie at the few @xmath0 level, not as strong as previously believed.   we briefly discuss prospects for further improvement.
using rxte / pca data, we have studied the time lag ( tl ) properties of a sample of four accreting neutron stars ( nss ), namely 2,, 705  and.   the aim of the study is to identify the spectral and timing state(s ) in which tls are detected. along this work  , we have discovered tls between the 7 - 40 kev hard and 2 - 7 kev soft photons from  with amplitudes similar to those seen in  ( i.e. @xmath0 ms at 5 hz ).   we show that the tls are only seen in the low states of those sources, but that within the so - called `` island '' spectral state, some sources display tls whereas some do not. on the other hand, we have found that tls are detected when the associated power density spectrum ( pds ) shows excess power at high frequencies ( above @xmath1 hz )  .    7054u1705 - 44 21e1724 - 3045
we present keck / esi long - slit spectroscopy of sbs 1421 + 511, a system consisting of a quasar at z = 0.276 and an extended source 3@xmath0 northern to the quasar.   the quasar shows a blue - skewed profile of balmer broad emission lines, which can be well modeled as emissions from a circular disk with a blueshift velocity of @xmath11400 @xmath2.   the blueshift is better interpreted as resulting from a recoiling active black hole than from a super - massive black hole binary, since the line profile almost kept steady over one decade in the quasar rest - frame.   alternative interpretations are possible as well, such as emissions from a bipolar outflow or a circular disk with spiral emissivity perturbations.   the extended source shows seyfert - like narrow line ratios and a  luminosity of @xmath3, with almost the same redshift as the quasar and a projected distance of 12.5 kpc at the redshift.   sbs 1421 + 511 is thus likely to be an interacting galaxy pair with dual agn.   alternatively, the quasar companion only appears to be active but not necessarily so : the gas before / in / behind the companion galaxy is illuminated by the quasar as an extended emission line region is detected at a similar distance in the opposite direction southern to the quasar, which may be generated either by tidal interactions between the galaxy pair or large - scale outflows from the quasar.
we present a general procedure for calculating one - loop `` casimir '' energy densities for a scalar field coupled to a fixed potential in renormalized quantum field theory.   we implement direct subtraction of counterterms computed precisely in dimensional regularization with a definite renormalization scheme.   our procedure allows us to test quantum field theory energy conditions in the presence of background potentials spherically symmetric in some dimensions and independent of others.   we explicitly calculate the energy density for several examples. for a square barrier  , we find that the energy is negative and divergent outside the barrier, but there is a compensating divergent positive contribution near the barrier on the inside.   we also carry out calculations with exactly solvable @xmath0 potentials, which arise in the study of solitons and domain walls.   + pacs 03.65.nk 11.10.gh 11.27.+d 11.55.hx
it is known that schrdinger equation fails in describing the dynamics of highly energetic particles.   we propose to quantify this lack of lorentz covariance by evaluating the probability for a particle to be measured outside the set of light cones which are compatible to its initial wave function.   we consider a simple case of a particle released from a box, which, in turn, is inside a larger container.   it is shown that besides the increasing error at relativistic energies, there may be a complete breakdown, with schrdinger dynamics implying in deterministic, superluminal signaling for lorentz factors above 129.   in addition, we give an exact asymptotic expression for the violation in local causality by employing the stationary exponent method, from which the compton wave length of the particle naturally arises as the relevant scale for the stationary points.   february 2016
we study polar coding over channels and sources with memory. we show that @xmath0-mixing processes polarize under the standard transform, and that the rate of polarization to deterministic distributions is roughly @xmath1 as in the memoryless case, where @xmath2 is the blocklength.   this implies that the error probability guarantees of polar channel and source codes extend to a large class of models with memory, including finite - order markov sources and finite - state channels.   channels with memory, polar codes, mixing, periodic processes, fast polarization, rate of polarization.
we present a systematic analysis of the x - ray spectra of ngc 1313 x-1 and ngc 1313 x-2, using three years of _ xmm - newton _ observations.   we fitted the continuum with a comptonization model plus a multicolor blackbody disc, that describes the effects of an accretion disc plus a corona.   we checked the consistency of this spectral model on the basis of the variability patterns of its spectral parameters.   we found that the two sources show different spectral states.   we tentatively interpret the observed behaviour of ngc 1313 x-1 and x-2 within the framework of near eddington and/or super - eddington accretion.   we also attempted to determine the chemical abundances in the local environment of ngc 1313 x-1 and x-2 from the epic and rgs spectra.   the results appear to indicate subsolar metallicity for both sources.       accretion, accretion discs  x - rays : binaries  x - rays : galaxies  x - rays : individuals ( ngc 1313 x-1, ngc 1313 x-2 )
we propose a method to estimate the pseudo jet opening half - angle of grbs using the spectral peak energy ( @xmath0)peak luminosity relation ( so called yonetoku relation ) as well as the @xmath0collimation - corrected @xmath1-ray energy relation ( so called ghirlanda relation ). for bursts with known jet break times and redshifts, we compared the pseudo jet opening half - angle with the standard one and found that the differences are within a factor 2.   we apply the method to 689 long grbs.   we found that the distribution function of the pseudo jet opening half - angle obeys @xmath2 with possible cutoffs for @xmath3 and @xmath4 although the log - normal fit is also possible.   @xmath5 distribution is compatible with the structured jet model. from the distribution function we found that the beaming correction for the rate of grbs is @xmath6, which means @xmath7  yr@xmath8  galaxy@xmath8 or only one in @xmath9  type ib / c supernovae.   we also found the evolution of the distribution function as a function of the redshift.       gamma rays : bursts  gamma rays : observations  gamma rays : theory.
we have studied the high - frequency properties of the non - equilibrium electron gas in gan samples subjected to electric and magnetic fields.   spectra of the complex tensor of the dynamical mobility have been calculated for thz frequency range. for the   compensated gan and low temperatures, in the intervals of electric fields of the few @xmath0 and magnetic fields of the few @xmath1 the existence of the cyclotron and optical phonon transit - time resonances has been identified.   we have shown that interplay of two resonances gives rise to specific spectra of thz transmission and absorption ( or gain ).   we suggest that experimental investigation of these effects will facilitate elaboration of field controlled devices for thz optoelectronics.   accepted for publication in
dilepton and photon production in heavy - ion collisions at sps energies are studied in the relativistic transport model that incorporates self - consistently the change of hadron masses in dense matter.   it is found that the dilepton spectra in proton - nucleus reactions can be well described by the conventional mechanism of dalitz decay and direct vector meson decay.   however, to provide a quantitative explanation of the observed dilepton spectra in central heavy - ion collisions requires contributions other than these direct decays and also various medium effects. introducing a decrease of vector meson masses in hot dense medium, we find that these heavy - ion data can be satisfactorily explained.   furthermore, the single photon spectra in our calculations with either free or in - medium meson masses do not exceed the upper bound deduced from the experiments by the wa80 collaboration.
the parallel computational complexity or depth of growing network models is investigated.   the networks considered are generated by preferential attachment rules where the probability of attaching a new node to an existing node is given by a power, @xmath0 of the connectivity of the existing node.   algorithms for generating growing networks very quickly in parallel are described and studied.   the sublinear and superlinear cases require distinct algorithms. as a result  , there is a discontinuous transition in the parallel complexity of sampling these networks corresponding to the discontinuous structural transition at @xmath1, where the networks become scale free. for @xmath2 networks can be generated in constant time while for @xmath3 logarithmic parallel time is required.   the results show that these networks have little depth and embody very little history dependence despite being defined by sequential growth rules.
we have investigated the faraday rotation of in - plane magnetized bismuth - substituted ferrite garnet films grown by liquid phase epitaxy on ( 100 ) oriented gadolinium gallium garnet substrates.   the faraday spectra were measured for photon energies between 1.7 - 2.6 ev. to interprete the spectra  , we use a model based on two electric dipole transitions, one tetrahedral and one octahedral.   furthermore, the faraday rotation sensitivity was measured at 2.3 ev, and found to be in good agreement with the theoretical predicitions.   in particular, we find that the sensitivity increases linearly with the bismuth content and nonlinearly with the gallium content.
we present images and a color  magnitude diagram for and v, a new dwarf spheroidal companion to m31 that was found using a digital filtering technique applied to 1550 deg@xmath0 of the second palomar sky survey. and   v resolves into stars easily in follow - up 4-m @xmath1- and @xmath2-band images, from which we deduce a distance of 810 @xmath3 45 kpc using the tip of the red giant branch method. within the uncertainties,   this distance is identical to the population ii distances for m31 and, combined with a projected separation of 112 kpc, provides strong support for a physical association between the two galaxies.   there is no emission from and v detected in h@xmath4, 1.4 ghz radio continuum, or iras bandpasses, and there is no young population seen in the color  magnitude diagram that might suggest that and v is an irregular.   thus, the classification as a new dwarf spheroidal member of the local group seems secure. with an extinction - corrected central surface brightness of 25.2 @xmath1 mag / arcsec@xmath0, a mean metal abundance of  @xmath5 1.5, and no evidence for upper agb stars, and v resembles and i & iii.
plasma diagnostics, radiation hydrodynamics, free electron laser    collective x - ray thomson scattering has become a versatile tool for the diagnostics of dense plasmas. assuming homogeneous density and temperature throughout the target sample, these parameters can be determined directly from the plasmon dispersion and the ratio of plasmon amplitudes via detailed balance. in inhomogeneous media, the scattering signal is an average of the density and temperature dependent scattering cross - section weighted with the density and temperature profiles.   we analyse thomson scattering spectra in the xuv range from near solid density hydrogen targets generated by free electron laser radiation.   the influence of plasma inhomogeneities on the scattering spectrum is investigated by comparing density and temperature averaged scattering signals to calculations assuming homogeneous targets.   we found discrepancies larger than 10% between the mean electron density and the effective density as well as between the mean temperature and the effective temperature.
the heating mechanism of a corona above an accretion disk in active galactic nuclei ( agns ) is still unknown.   one possible mechanism is magnetic reconnection heating requiring energy equipartition between magnetic energy and gas energy in the disk. here, we investigate the expected observed properties in radio band from such a magnetized corona.   a magnetized corona can generate synchrotron radiation since a huge amount of electrons exists.   although most of radiation would be absorbed by synchrotron self - absorption, high - frequency end of synchrotron emission can escape from a corona and appears at the sub - mm range. if only thermal electrons exist in a corona, the expected flux from nearby seyferts is below the atacama large millimeter/ submillimeter array ( alma ) sensitivity.   however, if non - thermal electrons coexist in a corona, alma can measure the non - thermal tail of the synchrotron radiation from a corona.   such non - thermal population is naturally expected to exist if the corona is heated by magnetic reconnections.   future alma observations will directly probe the coronal magnetic field strength and the existence of non - thermal electrons in coronae of agns.
the super - inflationary phase is predicted by the loop quantum cosmology. in this paper   we study the creation of gravitational waves during this phase.   we consider the inverse volume corrections to the equation for the tensor modes and calculate the spectrum of the produced gravitons.   the amplitude of the obtained spectrum as well as maximal energy of gravitons strongly depend on the evolution of the universe after the super - inflation.   we show that a further standard inflationary phase is necessary to lower the amount of gravitons below the present bound. in case of the lack of the standard inflationary phase  , the present intensity of gravitons would be extremely large.   these considerations give us another motivation to introduce the standard phase of inflation.
the euler - lagrange equation of the phase - field crystal ( pfc ) model has been solved under appropriate boundary conditions to obtain the equilibrium free energy of the body centered cubic crystal - liquid interface for 18 orientations at various reduced temperatures in the range @xmath0 $ ].   while the maximum free energy corresponds to the @xmath1 orientation for all @xmath2 values, the minimum is realized by the @xmath3 direction for small @xmath4, and by the @xmath5 orientation for higher @xmath2.   the predicted dependence on the reduced temperature is consistent with the respective mean field critical exponent.   the results are fitted with an eight - term kubic harmonic series, and are used to create stereographic plots displaying the anisotropy of the interface free energy.   we have also derived the corresponding wulff shapes that vary with increasing @xmath2 from sphere to a polyhedral form that differs from the rhombo - dodecahedron obtained previously by growing a bcc seed until reaching equilibrium with the remaining liquid.   solidification, surface energy anisotropy, wulff shape, phase - field crystal model
we performed imaging on 49 type 2 seyfert galaxies in 6 near- and mid - infrared bands ( 1 - 10@xmath0 m ). we are separating the contribution of the torus from the host galaxy by radial profile fitting techniques and we will compare the observed spectral energy distributions with theoretical models of torus emission to constrain geometrical and physical parameters.
we provide a first - principles, perturbative derivation of the @xmath0/@xmath1 y - system that has been proposed to solve the spectrum problem of @xmath2 sym.   the proof relies on the computation of quantum effects in the fusion of some loop operators, namely the transfer matrices.   more precisely we show that the leading quantum corrections in the fusion of transfer matrices induce the correct shifts of the spectral parameter in the t - system. as intermediate steps   we study uv divergences in line operators up to first order and compute the fusion of line operators up to second order for the pure spinor string in @xmath3.   we also argue that the derivation can be easily extended to other integrable models, some of which describe string theory on @xmath4, @xmath5 and @xmath6 spacetimes.   theoretische natuurkunde, vrije universiteit brussel and + the international solvay institutes, + pleinlaan 2, b-1050 brussels, belgium + _raphael.benichou@vub.ac.be_
a novel approach to solve the faddeev equation for three - body scattering at arbitrary energies is proposed.   this approach disentangles the complicated singularity structure of the free three - nucleon propagator leading to the moving and logarithmic singularities in standard treatments.   the faddeev equation is formulated in momentum space and directly solved in terms of momentum vectors without employing a partial wave decomposition. in its simplest form   the faddeev equation for identical bosons, which we are using, is an integral equation in five variables, magnitudes of relative momenta and angles.   the singularities of the free propagator and the deuteron propagator are now both simple poles in two different momentum variables, and thus can both be integrated with standard techniques.
we show that the various crossovers between dynamical regimes observed in experiments and simulations of supercooled liquids can be explained in simple terms from the existence and statistical properties of dynamical heterogeneities.   we confirm that dynamic heterogeneity is responsible for the slowing down of glass formers at temperatures well above the dynamic singularity @xmath0 predicted by mode coupling theory.   our results imply that activated processes govern the long - time dynamics even in the temperature regime where they are neglected by mode - coupling theory.   we show that alternative interpretations based on topographic properties of the potential energy landscape are complicated and inefficient ways of describing simple physical features which are naturally accounted for within our approach.   we show in particular that the reported links between mode coupling and landscape singularities do not exist.
the cross - kerr nonlinearity ( xknl ) effect can induce efficient photon interactions in principle with which photonic multiqubit gates can be performed using far fewer physical resources than linear optical schemes.   unfortunately, it is extremely challenging to generate giant cross - kerr nonlinearities. in recent years  , much effort has been made to perform multiqubit gates via weak xknls.   however, the required nonlinearity strengths are still difficult to achieve in the experiment.   we here propose an xknl - based scheme for realizing a two - photon polarization - parity gate, a universal two - qubit gate, in which the required strength of the nonlinearity could be orders of magnitude weaker than those required for previous schemes.   the scheme utilizes a ring cavity fed by a coherent state as a quantum information bus which interacts with a path mode of the two polarized photons ( qubits ).   the xknl effect makes the bus pick up a phase shift dependent on the photon number of the path mode. even when the potential phase shifts are very small they can be effectively measured using photon - number resolving detectors, which accounts for the fact that our scheme can work in the regime of tiny xknl.   the measurement outcome reveals the parity ( even parity or odd parity ) of the two polarization qubits.
we predict various detectable mechanical responses to the presence of local dna defects which are defined as short dna segments exhibiting mechanical properties obviously different from the 50 nm persistence length based semiflexible polymer model.   the defects discussed are kinks and flexible hinges either permanently fixed on dna or thermally excited.   their effects on extension shift, the effective persistence length, the end - to - end distance distribution, and the cyclization probability are computed using a transfer - matrix method.   our predictions will be useful in future experimental designs to study dna nicks or mismatch base pairs, mechanics of specific dna sequences, and specific dna - protein interaction using magnetic tweezer, fluorescence resonance energy transfer or plasmon resonance technique, and the traditional biochemistry cyclization probability measurements.
the influence of the spin - orbit interactions on the energy spectrum of two - electron laterally coupled quantum dots is investigated.   the effective hamiltonian for a spin qubit pair proposed in f.baruffa et al.  , phys.   rev.   lett.   104, 126401 ( 2010 ) is confronted with exact numerical results in single and double quantum dots in zero and finite magnetic field.   the anisotropic exchange hamiltonian is found quantitatively reliable in double dots in general.   there are two findings of particular practical importance : i ) the model stays valid even for maximal possible interdot coupling ( a single dot ), due to the absence of a coupling to the nearest excited level, a fact following from the dot symmetry.   ii ) in a weak coupling regime, the heitler - london approximation gives quantitatively correct anisotropic exchange parameters even in a finite magnetic field, although this method is known to fail for the isotropic exchange.   the small discrepancy between the analytical model ( which employs the linear dresselhaus and bychkov - rashba spin - orbit terms ) and the numerical data for gaas quantum dots is found to be mostly due to the cubic dresselhaus term.   @twocolumnfalse    1.5truecm
we extend the notion of intersection graphs for chord diagrams in the theory of finite type knot invariants to chord diagrams for string links.   we use our definition to develop weight systems for string links via the adjacency matrix of the intersection graphs, and show that these weight systems are related to the weight systems induced by the conway and homfly polynomials.
the discovery of very - high - energy ( vhe, @xmath0  gev ) @xmath1-ray emission from intermediate- and low - frequency peaked blazars suggests that @xmath2 absorption and pair cascading might occur in those objects. in previous papers, we investigated the compton emission from vhe @xmath1-ray induced pair cascades, deflected by moderate magnetic fields, in a largely model - independent way, and demonstrated that this emission can explain the fermi fluxes and spectra of the radio galaxies cen  a and ngc  1275. in this paper, we describe a generalization of our monte - carlo cascade code to include the angle - dependent synchrotron output from the cascades, allowing for the application to situations with non - negligible magnetic fields, leading to potentially observable synchrotron signatures, but still not dominating the radiative energy loss of cascade particles.   we confirm that the synchrotron radiation from the cascades in ngc  1275 and cen  a are negligible for the parameters used in our previous works.   we demonstrate that the magnetic field can not be determined from a fit of the cascade emission to the @xmath1-ray spectrum alone, and the degeneracy can only be lifted if the synchrotron emission from the cascades is observed as well.   we illustrate this fact with the example of ngc  1275.   we point out that the cascade synchrotron emission may produce spectral features in the same energy range in which the big blue bump is observed in the spectral energy distributions of several blazars, and may make a non - negligible contribution to this feature.   we illustrate this idea with the example of 3c  279.
two different types of self - organizing and sustaining ordered motion in fluids or plasmas one is a bnard convection ( or streamer ) and the other is a zonal flow  have been compared by introducing a thermodynamic phenomenological model and evaluating the corresponding entropy production rates ( ep ).   these two systems have different topologies in their equivalent circuits : the bnard convection is modeled by parallel connection of linear and nonlinear conductances, while the zonal flow is modeled by series connection.   the `` power supply '' that drives the systems is also a determinant of operating modes.   when the energy flux is a control parameter ( as in usual plasma experiments ), the driver is modeled by a constant - current power supply, and when the temperature difference between two separate boundaries is controlled ( as in usual computational studies ), the driver is modeled by a constant - voltage power supply. the parallel ( series)-connection system tends to minimize ( maximize ) the total ep when a constant - current power supply drives the system.   this minimum / maximum relation flips when a constant - voltage power supply is connected.
the interplay of membrane proteins is vital for many biological processes, such as cellular transport, cell division, and signal transduction between nerve cells.   theoretical considerations have led to the idea that the membrane itself mediates protein self - organization in these processes through minimization of membrane curvature energy. here, we present a combined experimental and numerical study in which we quantify these interactions directly for the first time. in our experimental model system   we control the deformation of a lipid membrane by adhering colloidal particles. using confocal microscopy  , we establish that these membrane deformations cause an attractive interaction force leading to reversible binding.   the attraction extends over 2.5 times the particle diameter and has a strength of three times the thermal energy ( ).   coarse - grained monte - carlo simulations of the system are in excellent agreement with the experimental results and prove that the measured interaction is independent of length scale.   our combined experimental and numerical results reveal membrane curvature as a common physical origin for interactions between any membrane - deforming objects, from nanometre - sized proteins to micrometre - sized particles.
dynamic reconfiguration is the action of modifying a software system at runtime.   several works have been using architectural specification as the basis for dynamic reconfiguration. indeed adls ( architecture description languages )   let architects describe the elements that could be reconfigured as well as the set of constraints to which the system must conform during reconfiguration. in this work  , we investigate the adl literature in order to illustrate how reconfiguration is supported in four well - known adls : @xmath0-adl, acme, c2sadl and dynamic wright. from this review, we conclude that none of these adls : ( i ) addresses the issue of consistently reconfiguring both instances and types ; ( ii ) takes into account the behaviour of architectural elements during reconfiguration ; and ( iii ) provides support for assessing reconfiguration, e.g., verifying the transition against properties.
a comodule algebra @xmath0 over a hopf algebra @xmath1 with bijective antipode is called principal if the coaction of @xmath1 is galois and @xmath0 is @xmath1-equivariantly projective ( faithfully flat ) over the coaction - invariant subalgebra  @xmath2.   we prove that principality is a piecewise property : given @xmath3 comodule - algebra surjections @xmath4 whose kernels intersect to zero, @xmath0 is principal if and only if all @xmath5 s are principal. furthermore,   assuming the principality of @xmath0, we show that the lattice these kernels generate is distributive if and only if so is the lattice obtained by intersection with @xmath2.   finally, assuming the above distributivity property, we obtain a flabby sheaf of principal comodule algebras over a certain space that is universal for all such @xmath3-families of surjections @xmath4 and such that the comodule algebra of global sections is @xmath0.
molecular communication emerges as a promising communication paradigm for nanotechnology.   however, solid mathematical foundations for information - theoretic analysis of molecular communication have not yet been built.   in particular, no one has ever proven that the channel coding theorem applies to molecular communication, and no relationship between information rate capacity ( maximum mutual information ) and code rate capacity ( supremum achievable code rate ) has been established. in this paper, we focus on a major sub - class of molecular communication  the diffusion - based molecular communication.   we provide solid mathematical foundations for information theory in diffusion - based molecular communication by creating a general diffusion - based molecular channel model in measure - theoretic form and prove its channel coding theorems. various equivalence relationships between statistical and operational definitions of channel capacity   are also established, including the most classic information rate capacity and code rate capacity. as byproducts  , we have shown that the diffusion - based molecular channel is with `` asymptotically decreasing input memory and anticipation '' and `` @xmath0-continuous ''.   other properties of diffusion - based molecular channel such as stationarity or ergodicity are also proven.    molecular communication, diffusion process  , diffusion - based molecular system, channel capacity, nanotechnology, @xmath0-continuous channel, asymptotically decreasing input memory and anticipation channel, permutation channel, cascade of channels.
lyman - alpha ( ly@xmath0 ) is the strongest emission line in the universe and is frequently used to detect and study the most distant galaxies. because lya is a resonant line, photons typically scatter prior to escaping ; this scattering process complicates the interpretation of ly@xmath0 spectra, but also encodes a wealth of information about the structure and kinematics of neutral gas in the galaxy. modeling the ly@xmath0 line therefore allows us to study tiny - scale features of the gas, even in the most distant galaxies. curiously, observed ly@xmath0 spectra can be modeled successfully with very simple, homogeneous geometries ( such as an expanding, spherical shell ), whereas more realistic, multiphase geometries often fail to reproduce the observed spectra.   this seems paradoxical since the gas in galaxies is known to be multiphase. in this letter  , we show that spectra emerging from _ extremely _ clumpy geometries with many clouds along the line of sight converge to the predictions from simplified, homogeneous models.   we suggest that this resolves the apparent discrepancy, and may provide a way to study the gas structure in galaxies on scales far smaller than can be probed in either cosmological simulations or direct ( i.e., spatially - resolved ) observations.
pseudocapacitors are energy - storage devices characterized by fast and reversible redox reactions that enable them to store large amounts of electrical energy at high rates.   we simulate the response of pseudocapacitive electrodes under realistic conditions to identify the microscopic factors that determine their performance, focusing on ruthenia ( ruo@xmath0 ) as a prototypical electrode material.   electronic - structure methods are used together with a self - consistent continuum solvation model to build a complete database of free energies as the surface of the charged electrode is gradually covered with protons under applied voltage.   the resulting database is exploited to compute hydrogen - adsorption isotherms and charge   voltage responses by means of grand - canonical sampling, finding close agreement with experimental voltammetry.   these simulations reveal that small changes on the order of 5 @xmath1f/@xmath2 in the intrinsic double - layer capacitance of the electrode   electrolyte interface can induce variations of up to 40 @xmath1f/@xmath2 in the overall pseudocapacitance.
we compute the decoupling constant @xmath0 relating light quark masses of effective @xmath1-flavour qcd to @xmath2-flavour qcd to four - loop order.   immediate applications are the evaluation of the @xmath3 charm quark mass with five active flavours and the bottom quark mass at the scale of the top quark or even at gut scales. with the help of a low - energy theorem @xmath0   can be used to obtain the effective coupling of a higgs boson to light quarks with five - loop accuracy.   we briefly discuss the influence on @xmath4.   pacs numbers : 12.38.-t, 12.38.bx, 14.65.dw, 14.65.fy
replicating or caching popular content in memories distributed across the network is a technique to reduce peak network loads.   conventionally, the main performance gain of this caching was thought to result from making part of the requested data available closer to end users.   instead, we recently showed that a much more significant gain can be achieved by using caches to create coded - multicasting opportunities, even for users with different demands, through coding across data streams.   these coded - multicasting opportunities are enabled by careful content overlap at the various caches in the network, created by a central coordinating server.    in many scenarios,   such a central coordinating server may not be available, raising the question if this multicasting gain can still be achieved in a more decentralized setting. in this paper  , we propose an efficient caching scheme, in which the content placement is performed in a decentralized manner.   in other words, no coordination is required for the content placement. despite this lack of coordination,   the proposed scheme is nevertheless able to create coded - multicasting opportunities and achieves a rate close to the optimal centralized scheme.
diffuse @xmath0-ray emission arising from interactions of cosmic rays with the interstellar gas traces the densities of both of them throughout the milky way.   we discuss the results obtained from the analysis of _ fermi _ lat observations in the region of cassiopeia and cepheus, towards the perseus spiral arm.   we find that the @xmath0-ray emissivity of local gas is consistent with expectations based on the cosmic - ray spectra measured at the earth.   the emissivity decreases from the gould belt to the perseus arm, but the measured gradient is flatter than predictions by a propagation model based on a cosmic - ray source distribution peaking in the inner galaxy as suggested by pulsars.   the @xmath1 conversion factor moderately increases by a factor @xmath2 from the gould belt to the perseus arm.   the presence of additional gas not properly traced by @xmath3 and co surveys in the gould belt is suggested by the correlation between @xmath0-rays and thermal emission from cold interstellar dust.
the hadronic particle production data from relativistic nuclear pb   pb 158 a gev collisions are successfully described within the chemical non - equilibrium model, provided that the analysis treats @xmath0 and @xmath1 abundances with care.   we further show that there is a subtle influence of the coulomb potential on strange quarks in quark matter which is also seen in our data analysis, and this coulomb effect confirms the finding made by chemical analysis in the s   au / w / pb 200 a gev collisions that the hadron particle source is deconfined with respect to strange quark propagation. physical freeze - out conditions ( pressure, specific energy, entropy, and strangeness ) are evaluated and considerable universality of hadron freeze - out between the two different collision systems is established.   + pacs numbers 25.75.-q, 12.38.mh, 24.85.+p    = -0.3cm= -0.3 cm = -1.7cm=245.0 mm 0.5 cm    = 10000
gdel s completeness theorem is concerned with provability, while girard s theorem in ludics ( as well as full completeness theorems in game semantics ) are concerned with proofs.   our purpose is to look for a connection between these two disciplines. following a previous work @xcite  , we consider an extension of the original ludics with contraction and universal nondeterminism, which play dual roles, in order to capture a polarized fragment of linear logic and thus a constructive variant of classical propositional logic.   we then prove a completeness theorem for proofs in this extended setting : for any behaviour ( formula ) @xmath0 and any design ( proof attempt ) @xmath1, either @xmath1 is a proof of @xmath0 or there is a model @xmath2 of @xmath3 which defeats @xmath1. compared with proofs of full completeness in game semantics, ours exhibits a striking similarity with proofs of gdel s completeness, in that it explicitly constructs a countermodel essentially using knig s lemma, proceeds by induction on formulas, and implies an analogue of lwenheim - skolem theorem.
drilling holes in a bulk high - tc superconductor enhances the oxygen annealing and the heat exchange with the cooling liquid.   however, drilling holes also reduces the amount of magnetic flux that can be trapped in the sample. in this paper  , we use the bean model to study the magnetization and the current line distribution in drilled samples, as a function of the hole positions.   a single hole perturbs the critical current flow over an extended region that is bounded by a discontinuity line, where the direction of the current density changes abruptly.   we demonstrate that the trapped magnetic flux is maximized if the center of each hole is positioned on one of the discontinuity lines produced by the neighbouring holes. for a cylindrical sample,   we construct a polar triangular hole pattern that exploits this principle ; in such a lattice, the trapped field is @xmath0 higher than in a squared lattice, for which the holes do not lie on discontinuity lines.   this result indicates that one can simultaneously enhance the oxygen annealing, the heat transfer, and maximize the trapped field.   _ keywords _ : bulk hts, artificial holes, trapped field
the error propagation and statistical - noise reduction method of reid and trainor for two - point correlation applications in high - energy collisions is extended to include particle - pair references constructed by mixing two particles from all event - pair combinations within event subsets of arbitrary size.   the reid - trainor method is also applied to other particle - pair mixing algorithms commonly used in correlation analysis of particle production from high - energy nuclear collisions. the statistical - noise reduction, inherent in the reid - trainor event - mixing procedure,   is shown to occur for these other event - mixing algorithms as well.   monte carlo simulation results are presented which verify the predicted degree of noise reduction. in each case   the final errors are determined by the bin - wise particle - pair number, rather than by the bin - wise single - particle count.   correlation, event - mixing, noise reduction, error propagation
we combine a recently developed _   ab initio _ many - body approach capable of describing simultaneously both bound and scattering states, the _ ab initio _   ncsm / rgm, with an importance truncation scheme for the cluster eigenstate basis and demostrate its applicability to nuclei with mass numbers as high as 17. using   soft similarity renormalization group evolved chiral nucleon - nucleon interactions, we first calculate nucleon-@xmath0he phase shifts, cross sections and analyzing power.   next, we investigate nucleon scattering on @xmath1li, @xmath1be, @xmath2c and @xmath3o in coupled - channel ncsm / rgm calculations that include low - lying excited states of these nuclei.   we check the convergence of phase shifts with the basis size and study @xmath4, @xmath5, and @xmath6 bound and unbound states.   our calculations predict low - lying resonances in @xmath7li and @xmath7b that have not been experimentally clearly identified yet.   we are able to reproduce reasonably well the structure of the @xmath8 low lying states.   however, we find that @xmath9 states can not be described without an improved treatment of @xmath3o one - particle - one - hole excitations and @xmath10 clustering.
this paper presents a full derivation of the variance - to - mean or feynman - alpha formula in a two energy group- and two spatial region - treatment.   the derivation is based on the chapman - kolmogorov equation with the inclusion of all possible neutron reactions and passage intensities between the two regions.   in addition, the two - group one - region and the two - region one - group feynman - alpha formulas, treated earlier in the literature for special cases, are extended for further types and positions of detectors.   we focus on the possibility of using these theories for accelerator - driven systems and applications in the safeguards domain, such as the differential self - interrogation method and the differential die - away method.   this is due to the fact that the predictions from the models which are currently used do not fully describe all the effects in the heavily reflected fast or thermal systems.   therefore, in conclusion a comparative study of the two - group two - region, the two - group one - region, the one - group two - region and the one - group one - region feynman - alpha models is discussed.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
the hoop conjecture is well confirmed in momentarily static spaces, but it has not been investigated systematically for the system with relativistic motion. to confirm the hoop conjecture for non - time - symmetric initial data, we consider the initial data of two colliding black holes with momentum and search an apparent horizon that encloses two black holes. in testing the hoop conjecture, we use two definitions of gravitational mass : one is the adm mass and the other is the quasi - local mass defined by hawking.   although both definitions of gravitational mass give fairly consistent picture of the hoop conjecture, the hoop conjecture with the hawking mass can judge the existence of an apparent horizon for wider range of parameters of the initial data compared to the adm mass.
we use stereo imagery to study the morphology of a shock driven by a fast coronal mass ejection ( cme ) launched from the sun on 2011  march  7.   the source region of the cme is located just to the east of a coronal hole.   the cme ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole.   the result is a cme with ejecta not well centered within the shock surrounding it.   the shock shape inferred from the imaging is compared with in  situ data at 1  au, where the shock is observed near earth by the _ wind _ spacecraft, and at stereo - a.   shock normals computed from the in  situ data are consistent with the shock morphology inferred from imaging.
in order to explore any change caused by the g2 cloud approaching, we have monitored the flux density of sgr a@xmath0 at 22 ghz from feb.   2013 to aug.   2014 with a sub - array of japanese vlbi network.   the observation period included the expected periastron dates.   the number of observation epochs was 283 days.   we have observed no significant microwave enhancement of sgr a@xmath0 in the whole observation period.   the average flux density in the period is @xmath1 jy. the average is consistent with the usually observed flux density range of sgr a@xmath0 at 22 ghz.
the redshift evolution of the black hole - bulge relations is an essential observational constraint for models of black hole - galaxy coevolution.   in addition to the observational challenges for these studies, conclusions are complicated by the influence of selection effects.   we demonstrate that there is presently no statistical significant evidence for cosmological evolution in the @xmath0-bulge relations, once these selection effects are taken into account and corrected for.   we present a fitting method, based on the bivariate distribution of black hole mass and galaxy property, that accounts for the selection function in the fitting and is therefore able to recover the intrinsic black hole - bulge relation unbiased. while prior knowledge is restricted to a minimum, we at least require knowledge of either the sample selection function and the mass dependence of the active fraction, or the spheroid distribution function and the intrinsic scatter in the black hole - bulge relation.   we employed our fitting routine to existing studies of the @xmath1bulge relation at @xmath2 and @xmath3, using our current best knowledge of the distribution functions.   there is no statistical significant evidence for positive evolution in the @xmath4 ratio out to @xmath5. at @xmath3   the current constraints are less strong, but we demonstrate that the large observed _ apparent _ offset from the local @xmath1bulge relation at @xmath3 is fully consistent with no _ intrinsic _ offset.   the method outlined here provides a tool to obtain more reliable constraints on black hole - galaxy co - evolution in the future.       galaxies : active - galaxies : nuclei - quasars : general
the opera neutrino detector in the underground gran sasso laboratory ( lngs ) was designed to perform the first detection of neutrino oscillations in appearance mode through the study of @xmath0 oscillations.   the apparatus consists of an emulsion / lead target complemented by electronic detectors and it is placed in the high energy long - baseline cern to lngs beam ( cngs ) 730 km away from the neutrino source.   runs with cngs neutrinos were successfully carried out in 2007 and 2008 with the detector fully operational with its related facilities for the emulsion handling and analysis. after a brief description of the beam and of the experimental setup we report on the collection, reconstruction and analysis procedures of first samples of neutrino interaction events.   submitted to jinst
we study the ground state properties of a one - dimensional bose gas with @xmath0-body attractive contact interactions. by using the explicit form of the bright soliton solution of a generalized nonlinear schrdinger equation, we compute the chemical potential and the ground state energy.   for @xmath1, a localized soliton wave - function exists only for a critical value of the interaction strength : in this case the ground state has an infinite degeneracy that can be parameterized by the chemical potential.   the stabilization of the bright soliton solution by an external harmonic trap is also discussed, and a comparison with the effect of @xmath0-body attractive contact interactions in higher dimensions is presented.
we derive a hamiltonian version of the @xmath0-symmetric discrete nonlinear schrdinger equation that describes synchronized dynamics of coupled pendula driven by a periodic movement of their common strings. in the limit of weak coupling between the pendula  , we classify the existence and spectral stability of breathers ( time - periodic solutions localized in the lattice ) supported near one pair of coupled pendula.   orbital stability or instability of breathers is proved in a subset of the existence region.
in the forthcoming isda standard credit support annex ( scsa ), the trades denominated in non - g5 currencies as well as those include multiple currencies are expected to be allocated to the usd silo, where the contracts are collateralized by usd cash, or a different currency with an appropriate interest rate overlay to achieve the same economic effects. in this paper, we have presented a simple generic valuation framework for the _ clean price _ under the usd silo with the the detailed procedures for the initial term structure construction.   we have also shown that cross currency swap ( ccs ) basis spread can be expressed as a difference between two swap rates.    *p *        * keywords :* csa, scsa, ois, swap, collateralization, basis spreads, cross currency basis, cross currency swaption, hjm
variability amplitudes larger than 1 magnitude over time - scales of a few tens of minutes have recently been reported in the optical light - curves of several blazars. in order to independently verify the real occurrence of such extremely violent events  , we undertook an observational study of a selected sample of three blazars : pks0048@xmath0097, pks0754@xmath1100, and pks1510@xmath0089.   possible systematic error sources during data acquisition and reduction were carefully evaluated.   we indeed found flux variability at intra - night time - scales in all three sources, although no extremely violent behaviour, as reported by other authors, was detected.   we show that an incorrect choice of the stars used for differential photometry will, under fairly normal conditions, lead to spurious variability with large amplitudes on short time - scales.   wrong results of this kind can be avoided with the use of simple error - control techniques.   galaxies : active  galaxies : photometry  bl lacertae objects : general
in present report we review some preliminary results of investigation of higher orders of mean - field expansion for nambu  jona - lasinio model.   we discuss first results of investigation of next - to - next - to - leading order of mean - field expansion equations for four - quark and three - quark green functions.   we have considered equations for green functions of nambu  jona - lasinio model in mean - field expansion up to third order.
this study investigates that a characteristic time scale on an exchange rate market ( usd / jpy ) is examined for the period of 1998 to 2000. calculating power spectrum densities for the number of tick quotes per minute and averaging them over the year yield that the mean power spectrum density has a peak at high frequencies.   consequently it means that there exist the characteristic scales which dealers act in the market.   a simple agent model to explain this phenomenon is proposed.   this phenomena may be a result of stochastic resonance with exogenous periodic information and physiological fluctuations of the agents.   this may be attributed to the traders behavior on the market.   the potential application is both quantitative characterization and classification of foreign currency markets. +   + * key words.   power spectrum density, agent - based model, stochastic resonance *
non - equilibrium radiation diffusion is an important mechanism of energy transport in inertial confinement fusion, astrophysical plasmas, furnaces and heat exchangers. in this paper,   an analytical solution to the non - equilibrium marshak diffusion problem in a planar slab and spherical shell of finite thickness is presented. using laplace transform method,   the radiation and material energy densities are obtained as a function of space and time.   the variation in integrated energy densities and leakage currents are also studied. in order to linearize the radiation transport and material energy equation  , the heat capacity is assumed to be proportional to the cube of the material temperature.   the steady state energy densities show linear variation along the depth of the planar slab, whereas non - linear dependence is observed for the spherical shell.   the analytical energy densities show good agreement with those obtained from finite difference method using small mesh width and time step.   the benchmark results obtained in this work can be used to validate and verify non equilibrium radiation diffusion computer codes in both planar and spherical geometry.   key - words : non - equilibrium radiation diffusion, analytic solution, finite planar slab, spherical shell, laplace transform method, finite difference pacs : 44.05.+e, 44.40.+a
we investigate the possibility to explain theoretically the observed deviations of s2 star orbit around the galactic centre using gravitational potentials derived from modified gravity models in absence of dark matter. to this aim, an analytic fourth - order theory of gravity, non - minimally coupled with a massive scalar field   is considered.   specifically, the interaction term is given by analytic functions @xmath0 and @xmath1 where @xmath2 is the ricci scalar and @xmath3 is a scalar field whose meaning can be related to further gravitational degrees of freedom.   we simulate the orbit of s2 star around the galactic centre in @xmath0 ( yukawa - like ) and @xmath1 ( sanders - like ) gravity potentials and compare it with ntt / vlt observations.   our simulations result in strong constraints on the range of gravity interaction. in the case of analytic functions   @xmath0, we are not able to obtain reliable constraints on the derivative constants @xmath4 and @xmath5, because the current observations of s2 star indicated that they may be highly mutually correlated. in the case of analytic functions   @xmath1, we are able to obtain reliable constraints on the derivative constants @xmath6, @xmath7, @xmath8, @xmath9, @xmath10 and @xmath11. the approach we are proposing seems to be sufficiently reliable to constrain the modified gravity models from stellar orbits around galactic centre.
these notes summarise a talk surveying the combinatorial or hamiltonian quantisation of three dimensional gravity in the chern - simons formulation, with an emphasis on the role of quantum groups and on the way the various physical constants ( @xmath0 enter as deformation parameters.   the classical situation is summarised, where solutions can be characterised in terms of model spacetimes ( which depend on @xmath1 and @xmath2 ) together with global identifications via elements of the corresponding isometry groups.   the quantum theory may be viewed as a deformation of this picture, with quantum groups replacing the local isometry groups, and non - commutative spacetimes replacing the classical model spacetimes.   this point of view is explained, and open issues are sketched.   empg-11 - 11 +    28 pt    * quantum gravity and non - commutative spacetimes in three dimensions : a unified approach *    18 pt     bernd  j.  schroers + department of mathematics and maxwell institute for mathematical sciences + heriot - watt university + edinburgh eh14 4as, united kingdom    talk given at ` geometry and physics in cracow ', september 2010
spin effects in a normal two - dimensional ( 2d ) electron gas in lateral contact with a 2d region with spin - orbit interaction are studied.   the peculiarity of this system is the presence of spin - dependent scattering of electrons from the interface.   this results in an equilibrium edge spin current and nontrivial spin responses to a particle current.   we investigate the spatial distribution of the spin currents and spin density under non - equilibrium conditions caused by a ballistic electron current flowing normal or parallel to the interface.   the parallel electron current is found to generate the spin density near the interface and to change the edge spin current.   the perpendicular electron current changes the edge spin current proportionally to the electron current and produces a bulk spin current penetrating deep into the normal region.   this spin current has two components, one of which is directed normal to the interface and polarized parallel to it, and the second is parallel to the interface and is polarized in the plane perpendicular to the contact line.   both spin currents have a high degree of polarization ( @xmath0 ).
we present hubble space telescope ( hst ) and ground - based observations of a pair of galaxies at redshift 2.38, which are collectively known as 2142@xmath04420 b1 @xcite.   the two galaxies are both luminous extremely red objects ( eros ), separated by 0.8.   they are embedded within a 100 kpc scale diffuse ly@xmath1 nebula ( or blob ) of luminosity @xmath2.   the radial profiles and colors of both red objects are most naturally explained if they are young elliptical galaxies : the most distant yet found.   it is not, however, possible to rule out a model in which they are abnormally compact, extremely dusty starbursting disk galaxies.   if they are elliptical galaxies, their stellar populations have inferred masses of @xmath3 and ages of @xmath4 years.   both galaxies have color gradients : their centers are significantly bluer than their outer regions.   the surface brightness of both galaxies is roughly an order of magnitude greater than would be predicted by the kormendy relation.   a chain of diffuse star formation extending 1  from the galaxies may be evidence that they are interacting or merging.   the ly@xmath1 nebula surrounding the galaxies shows apparent velocity substructure of amplitude @xmath5.   we propose that the ly@xmath1 emission from this nebula may be produced by fast shocks, powered either by a galactic superwind or by the release of gravitational potential energy.
the production of @xmath0al by explosions of classical novae has been computed by means of a hydrodynamic code that follows both the accretion and the explosion stages.   a special emphasis has been put on the analysis of the influence of the initial abundances of the accreted envelope, as well as on the nuclear reaction rates involved. with the most recent values of chemical composition and reaction rates   available, @xmath0al production is lowered with respect to previous computations. according to our results, the final contribution of novae to the galactic @xmath0al is at most 0.4  m@xmath1, which is a small part of the estimated @xmath0al in the galaxy derived from comptel observations of the 1809 kev emission.   # 1
starting in 1999, the rossi x - ray timing explorer ( rxte ) has monitored the central bulge region of the galaxy with the proportional counter array ( pca ), resolving about 50 binary x - ray sources, including 18 sources discovered by rxte and bepposax.   the accretion rates that rxte observed from these sources ranged from highs approaching eddington limits to lows that may correspond to mass exchange for a binary period near the minimum of 80 minutes. several neutron star binaries with low peak luminosity   have outburst or cycle time - scales which are shorter than those of brighter and better known counterparts.   we compare the characteristics of the binaries with low rates of mass exchange to predictions of their evolution.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
a search for aligned events has been done throughout the muon groups events measured by baksan underground scintillation telescope ( bust ) during a period of 7.7 years.   only groups of multiplicity @xmath0 for muon threshold energy equal to 0.85 tev were selected for the analysis. a distribution of the events on alignment parameter @xmath1 has been obtained and compared with the results of monte - carlo simulation made for this experiment.   the upper limit for aligned muon event flux as low as @xmath2 @xmath3 is given.
a graphene nano - ribbon with armchair edges is known to have no edge state. however,   if the nano - ribbon is in the quantum spin hall state, then there must be helical edge states. by folding a graphene ribbon to a ring and threading it by a magnetic flux, we study the persistent charge and spin currents in the tight - binding limit.   it is found that, for a broad ribbon, the edge spin current approaches a finite value independent of the radius of the ring. for a narrow ribbon, inter - edge coupling between the edge states could open the dirac gap and reduce the overall persistent currents.   furthermore, by enhancing the rashba coupling, we find that the persistent spin current gradually reduces to zero at a critical value, beyond which the graphene is no longer a quantum spin hall insulator.
the objective of the present study is to mitigate, or even completely eliminate, the limit cycle oscillations in mechanical systems using a passive nonlinear absorber, termed the nonlinear tuned vibration absorber ( nltva ).   an unconventional aspect of the nltva is that the mathematical form of its restoring force is not imposed a priori, as it is the case for most existing nonlinear absorbers.   the nltva parameters are determined analytically using stability and bifurcation analyses, and the resulting design is validated using numerical continuation.   the proposed developments are illustrated using a van der pol - duffing primary system.   _ keywords _ : limit cycle oscillations, vibration absorber, nonlinearity synthesis, stability analysis, bifurcation analysis.   this is an author post - print, original manuscript at + http://rspa.royalsocietypublishing.org/content/471/2176/20140976 + g. habib, g. kerschen +    space structures and systems laboratory + department of aerospace and mechanical engineering + university of lige, lige, belgium + e - mail : giuseppe.habib,g.kerschen@ulg.ac.be +    corresponding author : + giuseppe habib + space structures and systems laboratory + department of aerospace and mechanical engineering + university of lige + 1 chemin des chevreuils ( b52/3 ), b-4000 lige, belgium. +   email : giuseppe.habib@ulg.ac.be.
adsorption of charged polymers ( polyelectrolytes ) from a semi  dilute solution to a charged surface is investigated theoretically.   we obtain simple scaling laws for ( i ) the amount of polymer @xmath0 adsorbed to the surface and ( ii ) the width @xmath1 of the adsorbed layer, as function of the fractional charge per monomer @xmath2 and the salt concentration @xmath3. for strongly charged polyelectrolytes ( @xmath4 ) in a low  salt solution,   both @xmath0 and @xmath1 scale as @xmath5. in salt   rich solutions @xmath6 whereas the scaling behavior of @xmath0 depends on the strength of the polymer charge. for weak polyelectrolytes ( @xmath7 )   we find that @xmath8 while for strong polyelectrolytes @xmath9.   our results are in good agreement with adsorption experiments and with numerical solutions of mean  field equations.
the deep lens survey ( dls ) is a deep @xmath0 imaging survey of seven @xmath1 degree fields, with all data to be made public.   the primary scientific driver is weak gravitational lensing, but the survey is also designed to enable a wide array of other astrophysical investigations.   a unique feature of this survey is the search for transient phenomena.   we subtract multiple exposures of a field, detect differences, classify, and release transients on the web within about an hour of observation. here   we summarize the scientific goals of the dls, field and filter selection, observing techniques and current status, data reduction, data products and release, and transient detections.   finally, we discuss some lessons which might apply to future large surveys such as lsst.
we study the concurrence of entanglement between two quantum dots in contact to majorana bound states on a floating superconducting island.   the distance between the majorana states, the charging energy of the island, and the average island charge are shown to be decisive parameters for the efficiency of entanglement generation.   we find that long - range entanglement with basically distance - independent concurrence is possible over wide parameter regions, where the proposed setup realizes a `` majorana entanglement bridge ''.   we also study the time - dependent concurrence obtained after one of the tunnel couplings is suddenly switched on, which reveals the timescales for generating entanglement.   accurate analytical expressions for the concurrence are derived both for the static and the time - dependent case.   our results indicate that entanglement formation in interacting majorana devices can be fully understood in terms of an interplay of elastic cotunneling ( also referred to as `` teleportation '' ) and crossed andreev reflection processes.
saturation is expected to occur when a high density of partons ( mainly gluons)- or equivalently strong fields in quantum chromodynamics ( qcd ) - is realized in the weak coupling regime.   a way to reach saturation is through the high - energy evolution of an extended target probed at a fixed hard scale. in this case  , the transition to saturation is expected to occur from nonlinear perturbative qcd dynamics.   we discuss this approach to saturation, which is mathematically characterized by the appearance of traveling wave patterns in a suitable kinematical representation.   a short review on traveling waves in high energy qcd and a first evidence of this phenomenon in deep - inelastic proton scattering are presented.   address = service de physique thorique, cea / saclay, 91191 gif - sur - yvette cedex, france + ura 2306, unit de recherche associe au cnrs
we use statistical inference theory to explore the constraints from future galaxy weak lensing ( cosmic shear ) surveys combined with the current cmb constraints on cosmological parameters, focusing particularly on the running of the spectral index of the primordial scalar power spectrum, @xmath0.   recent papers have drawn attention to the possibility of measuring @xmath0 by combining the cmb with galaxy clustering and/or the lyman-@xmath1 forest.   weak lensing combined with the cmb provides an alternative probe of the primordial power spectrum.   we run a series of simulations with variable runnings and compare them to semi - analytic non - linear mappings to test their validity for our calculations.   we find that a `` reference '' cosmic shear survey with @xmath2 and @xmath3 galaxies per steradian can reduce the uncertainty on @xmath4 and @xmath0 by roughly a factor of 2 relative to the cmb alone.   we investigate the effect of shear calibration biases on lensing by including the calibration factor as a parameter, and show that for our reference survey, the precision of cosmological parameter determination is only slightly degraded even if the amplitude calibration is uncertain by as much as 5%.   we conclude that in the near future weak lensing surveys can supplement the cmb observations to constrain the primordial power spectrum.
we study systems of globally coupled interval maps, where the identical individual maps have two expanding, fractional linear, onto branches, and where the coupling is introduced via a parameter - common to all individual maps - that depends in an analytic way on the mean field of the system.   we show : 1 ) for the range of coupling parameters we consider, finite - size coupled systems always have a unique invariant probability density which is strictly positive and analytic, and all finite - size systems exhibit exponential decay of correlations.   2 ) for the same range of parameters, the self - consistent perron - frobenius operator which captures essential aspects of the corresponding infinite - size system ( arising as the limit of the above when the system size tends to infinity ), undergoes a supercritical pitchfork bifurcation from a unique stable equilibrium to the coexistence of two stable and one unstable equilibrium.   .
an analysis of structure in rotation measure ( rm ) across the sky based on the rm catalog of @xcite is presented.   several resolved rm structures are identified with structure in the local ism, including radio loops i, ii, and iii, the gum nebula, and the orion - eridanus super bubble.   structure functions ( sfs ) of rm are presented for selected areas, and maps of sf amplitude and slope across the sky are compared with h@xmath0 intensity and diffuse polarized intensity.   rm variance on an angular scale of @xmath1 is correlated with length of the line of sight through the galaxy, with a contribution from local structures.   the slope of the sfs is less concentrated to the galactic plane and less correlated with length of the line of sight through the galaxy, suggesting a more local origin for rm structure on angular scales @xmath2.   the rm variance is a factor @xmath3 higher towards the sgp than towards the ngp, reflecting a more wide - spread asymmetry between the northern and southern galactic hemispheres.   depolarization of diffuse galactic synchrotron emission at latitudes @xmath4 can be explained largely by faraday dispersion related to small - scale variance in rm, but the errors allow a significant contribution from differential faraday rotation along the line of sight.
* star formation ; cluster formation * stellar clusters are born in cold and dusty molecular clouds and the youngest clusters are embedded to various degrees in dusty dark molecular material.   such embedded clusters can be considered protocluster systems.   the most deeply buried examples are so heavily obscured by dust that they are only visible at infrared wavelengths.   these embedded protoclusters constitute the nearest laboratories for direct astronomical investigation of the physical processes of cluster formation and early evolution.   i review the present state of empirical knowledge concerning embedded cluster systems and discuss the implications for understanding their formation and subsequent evolution to produce bound stellar clusters.   3co@xmath0co    
we investigate the ism environment of grb 060505. using optical emission - line diagnostic ratios, we compare the ism properties of the grb 060505 host region with the hosts of unambiguous long- and short- duration grbs.   we show that the metallicity, ionization state, and star formation rate of the grb 060505 environment are more consistent with short - duration grbs than with long - duration grbs.   we compare the metallicity and star formation rates of the grb 060505 region with four other star - forming regions within the grb 060505 host galaxy.   we find no significant change in metallicity or star formation rate between the grb 060505 region and the other four host regions.   our results are consistent with a compact - object - merger progenitor for grb 060505.
we present a catalog of precise eclipse times and analysis of third body signals among 1279 close binaries in the latest _ kepler _ eclipsing binary catalog. for these short period binaries,   _ kepler _   s 30 minute exposure time causes significant smearing of light curves.   in addition, common astrophysical phenomena such as chromospheric activity, as well as imperfections in the light curve detrending process, can create systematic artifacts that may produce fictitious signals in the eclipse timings.   we present a method to measure precise eclipse times in the presence of distorted light curves, such as in contact and near - contact binaries which exhibit continuously changing light levels in and out of eclipse.   236 systems for which we find a timing variation signal compatible with the presence of a third body are identified.   these are modeled for the light time travel effect and the basic properties of the third body are derived.   this study complements @xcite, which focuses on eclipse timing variations of longer period binaries with flat out - of - eclipse regions.   together, these two papers provide comprehensive eclipse timings for all binaries in the _ kepler _ eclipsing binary catalog, as an ongoing resource freely accessible online to the community.
many past attempts to kill mond have only strengthened the theory.   better data on galaxy velocity curves clearly favor mond ( without fine - tuning ) over cold dark matter.   the usual critism on the incompleteness of classical mond has spurred a modified relativity ( mr ) by bekenstein.   after outlining cosmology and lensing in mond, we review mond on small scales.   we point out some potential problems of mond in two - body relaxation and tidal truncation.   we argue that the tidal field in any mond - like gravity theory predicts that the roche lobe sizes of a binary system are simply proportional to the binary baryonic mass ratio to the power 1/3.   an immediate application of this result is that the tidal field and tidal truncation radii of million - star globular clusters and million - star dwarf galaxies ( e.g., the milky way satellites ngc2419 and carina ) would be very similar because of the one - to - one relation between gravity and baryon distribution.   this prediction appears, however, inconsistent with the fact that _ all _ globulars are truncated to much smaller sizes than _ all _ dwarf galaxies. whether tide is uniquely determined by baryons   can also be used to falsify any mond - like gravity theory, whether classical or relativistic.
we study the gravitational corrections to the maxwell, dirac and klein - gorden theories in the large extra dimension model in which the gravitons propagate in the ( 4+n)-dimensional bulk, while the gauge and matter fields are confined to the four - dimensional world.   the corrections to the two - point green s functions of the gauge and matter fields from the exchanges of virtual kaluza - klein gravitons are calculated in the gauge independent background field method. in the framework of effective field theory,   we show that the modified one - loop renormalizable lagrangian due to quantum gravitational effects contains a tev scale lee - wick partner of every gauge and matter field as extra degrees of freedom in the theory.   thus the large extra dimension model of gravity provides a natural mechanism to the emergence of these exotic particles which were recently used to construct an extension of the standard model.
a common strategy to measure the abelian geometric phase for a qubit is to let it evolve along an ` orange slice'shaped path connecting two antipodal points on the bloch sphere by two different semi - great circles. since the dynamical phases vanish for such paths, this allows for direct measurement of the geometric phase. here  , we generalize the orange slice setting to the non - abelian case.   the proposed method to measure the non - abelian geometric phase can be implemented in a cyclic chain of four qubits with controllable interactions.
we fit the ( quasi-)simultaneous multi - waveband spectral energy distributions ( seds ) for a sample of low - synchrotron - peaked ( lsp ) blazars with a one - zone leptonic model.   the seed photons that predominantly come from broad line region ( blr ) and infrared ( ir ) molecular torus are considered respectively in external compton process.   we find that the modeling with ir seed photons is systematically better than that with blr photons based on a @xmath0 test, which suggest that @xmath1-ray emitting region most possibly stay outside the blr.   the minimum electron lorentz factor, @xmath2, is constrained from the modeling for these lsp blazars with good soft x - ray data ( ranges from 5 to 160 with a median value of 55 ), which plays a key role in jet power estimation.   assuming one - to - one ratio of proton and electron, we find that the jet power for lsp blazars is systematically higher than that of fr ii radio galaxies at given 151 mhz radio luminosity, @xmath3, even though fr iis are regarded as same as lsp blazars in unification scheme except the jet viewing angle.   the possible reason is that there are some @xmath4 pairs in the jet of these blazars.   if this is the case, we find the number density of @xmath4 pairs should be several times higher than that of @xmath5 pairs by assuming the jet power is the same for lsp blazars and fr iis at given @xmath3.
stochastic games are a natural model for the synthesis of controllers confronted to adversarial and/or random actions.   in particular, @xmath0-regular games of infinite length can represent reactive systems which are not expected to reach a correct state, but rather to handle a continuous stream of events.   one critical resource in such applications is the memory used by the controller. in this paper  , we study the amount of memory that can be saved through the use of randomisation in strategies, and present matching upper and lower bounds for stochastic muller games.   florian horn
this paper presents a statistical analysis of the structure of peer - to - peer ( p2p ) social networks that captures social associations of distributed peers in resource sharing.   peer social networks appear to be mainly composed of pure resource providers that guarantee high resource availability and reliability of p2p systems.   the major peers that both provide and request resources are only a small fraction.   the connectivity between peers, including undirected, directed ( out and in ) and weighted connections, is scale - free and the social networks of all peers and major peers are small world networks.   the analysis also confirms that peer social networks show in general disassortative correlations, except that active providers are connected between each other and by active requesters.   the study presented in this paper gives a better understanding of peer relationships in resource sharing, which may help a better design of future p2p networks and open the path to the study of transport processes on top of real p2p topologies.   [ phys.   rev.   e * 73 *, 036123 ( 2006 ) ]
b - meson decays are very useful probes for testing the standard model and its various extensions.   leptonic decays of b have very clean signatures in this respect and hence can be very useful testing grounds. in this work we study the effects of mssm ( minimal supersymmetric extension of standard model ) on various kinematical distributions in the radiative dileptonic decay ( ).   we study the forward backward asymmetry ( of the lepton pair ), and the various polarization asymmetries of both final state leptons ( @xmath0 and @xmath1 ).   in radiative dileptonic decay of b - meson ( ) the final state photon can also be polarized.   so in this channel one can also study the polarization effects of the final state photon.
we investigate theoretically the low - temperature physics of a two - component ultracold mixture of bosons and fermions in disordered optical lattices.   we focus on the strongly correlated regime.   we show that, under specific conditions, composite fermions, made of one fermion plus one bosonic hole, form. the composite picture is used to derive an effective hamiltonian whose   parameters can be controlled via the boson - boson and the boson - fermion interactions, the tunneling terms and the inhomogeneities.   we finally investigate the quantum phase diagram of the composite fermions and we show that it corresponds to the formation of fermi glasses, spin glasses, and quantum percolation regimes.
here we focus on the description of the mechanisms behind the process of information aggregation and decision making, a basic step to understand emergent phenomena in society, such as trends, information spreading or the wisdom of crowds. in many situations,   agents choose between discrete options.   we analyze experimental data on binary opinion choices in humans. the data consists of two separate experiments in which humans answer questions with a binary response, where one is correct and the other is incorrect.   the questions are answered without and with information on the answers of some previous participants.   we find that a bayesian approach captures the probability of choosing one of the answers.   the influence of peers is uncorrelated with the difficulty of the question.   the data is inconsistent with weber s law, which states that the probability of choosing an option depends on the proportion of previous answers choosing that option and not on the total number of those answers.   last, the present bayesian model fits reasonably well to the data as compared to some other previously proposed functions although the latter sometime perform slightly better than the bayesian model.   the asset of the present model is the simplicity and mechanistic explanation of the behavior.
geometric integration theory can be employed when numerically solving odes or pdes with constraints. in this paper, we present several one - step algorithms of various orders for odes on a collection of spheres. to demonstrate the versatility of these algorithms, we present representative calculations for reduced free rigid body motion ( a conservative ode ) and a discretization of micromagnetics ( a dissipative pde ).   we emphasize the role of isotropy in geometric integration and link numerical integration schemes to modern differential geometry through the use of partial connection forms ; this theoretical framework generalizes moving frames and connections on principal bundles to manifolds with nonfree actions.
the phase diagram of two - color qcd with a chiral chemical potential is studied on the lattice.   the focus is on the confinement / deconfinement phase transition and the breaking / restoration of chiral symmetry.   the simulations are carried out with dynamical staggered fermions without rooting.   the dependence of the polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented.   address = institute of theoretical and experimental physics, 117218 moscow, russia     address = far eastern federal university, school of biomedicine, 690950 vladivostok, russia     address = joint institute for nuclear research, vblhep and bltp, 141980 dubna, russia,     address = institute of theoretical and experimental physics, 117218 moscow, russia     address = far eastern federal university, school of biomedicine, 690950 vladivostok, russia     address = humboldt - universitt zu berlin, institut fr physik, 12489 berlin, germany     address = humboldt - universitt zu berlin, institut fr physik, 12489 berlin, germany     address = humboldt - universitt zu berlin, institut fr physik, 12489 berlin, germany
we investigate the time evolution of an initial step profile separating a bare substrate region from the rest of the compressively strained adsorbate layer near a commensurate to incommensurate transition.   the rate of profile evolution as a function of the mismatch, coverage and the strength of the substrate potential are determined by brownian molecular dynamics simulations.   we find that the results are qualitatively similar to those observed for the pb / si(111 ) system.   the anomalously fast time evolution and sharpness of the non - equilibrium profile can be understood through the domain wall creation at the boundary and its subsequent diffusion into the interior of the adsorbate layer.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
we investigate the higgs inflation and the higgs portal dark matter with the right - handed neutrino. the dark matter and the right - handed neutrino in the higgs inflation play important roles in explaining the recent experimental results of the higgs and top masses, and the cosmic microwave background by bicep2 at the same time.   this inflation model predicts @xmath0 for the dm mass, @xmath1 for the right - handed neutrino mass, and @xmath2 for the non - minimal coupling within @xmath3 for the higgs and @xmath4 for the top masses  .    0.6 cm    su - het-06 - 2014    * higgs inflation and higgs portal dark matter + with right - handed neutrinos *    1.2 cm     naoyuki haba, hiroyuki ishida, and ryo takahashi    0.4 cm     _ graduate school of science and engineering, shimane university, + matsue 690 - 8504 japan _    0.2 cm   .5 in
we report the detection of polarized emission in the vicinity of the galactic center for 158 positions within eight different pointings of the hertz polarimeter operating on the caltech submillimeter observatory.   these pointings include positions 2 offset to the e, ne, and nw of m-0.02 - 0.07 ; positions to the se and nw of the 20 km s@xmath0 cloud ( m-0.13 - 0.08 ), co+0.02 - 0.02, m+0.07 - 0.08, and m+0.11 - 0.08.   we use these data in conjunction with previous far - infrared and submillimeter polarization results to find that the direction of the inferred magnetic field is related to the density of the molecular material in the following way : in denser regions, the field is generally parallel to the galactic plane, whereas in regions with lower densities, the field is generally perpendicular to the plane.   this finding is consistent with a model in which an initially poloidal field has been sheared into a toroidal configuration in regions that are dense enough such that the gravitational energy density is greater than the energy density of the magnetic field. using this model  , we estimate the characteristic strength of the magnetic field in the central 30 pc of our galaxy to be a few mg.
the critical behaviour of several spin models can be simply described as percolation of some suitably defined clusters, or droplets : the onset of the geometrical transition coincides with the critical point and the percolation exponents are equal to the thermal exponents.   it is still unknown whether, given a model, one can define at all the droplets. in the cases where this is possible  , the droplet definition depends in general on the specific model at study and can be quite involved.   we propose here a simple general definition for the droplets : they are clusters obtained by joining nearest - neighbour spins of the same sign with some bond probability @xmath0, which is the minimal probability that still allows the existence of a percolating cluster at the critical temperature @xmath1. by means of lattice monte carlo simulations   we find that this definition indeed satisfies the conditions required for the droplets, for many classical spin models, discrete and continuous, both in two and in three dimensions.   in particular, our prescription allows to describe exactly the confinement - deconfinement transition of @xmath2 gauge theories as polyakov loop percolation.    0.7 cm    0.5 cm    0.7 cm
we report detection of the low - mass secondary in the spectroscopic binary haro 1 - 14c in the ophiuchus star forming region.   the secondary / primary mass ratio is @xmath0. with an estimated photometric primary mass of 1.2  @xmath1,   the secondary mass is @xmath2 and the projected semi - major axis is @xmath3 au.   the system is well - suited for astrometric mapping of its orbit with the current generation of ground - based ir interferometers.   this could yield precision values of the system s component masses and distance.
if predictions for species extinctions hold, then the ` tree of life'today may be quite different to that in ( say ) 100 years.   we describe a technique to quantify how much each species is likely to contribute to future biodiversity, as measured by its expected contribution to phylogenetic diversity.   our approach considers all possible scenarios for the set of species that will be extant at some future time, and weights them according to their likelihood under an independent ( but not identical ) distribution on species extinctions.   although the number of extinction scenarios can typically be very large, we show that there is a simple algorithm that will quickly compute this index.   the method is implemented and applied to the prosimian primates as a test case, and the associated species ranking is compared to a related measure ( the ` shapley index').   we describe indices for rooted and unrooted trees, and a modification that also includes the focal taxon s probability of extinction, making it directly comparable to some new conservation metrics.    _   keywords : _ phylogenetic diversity, extinction, biodiversity conservation, shapley index    _ short title : _ taxon - specific indices of expected future biodiversity
a family of models of liquid on a 2d lattice ( 2d lattice liquid models ) have been proposed as primitive models of soft - material membrane. as a first step,   we have formulated them as single - component, single - layered, classical particle systems on a two - dimensional surface with no explicit viscosity. among the family of the models,   we have shown and constructed two stochastic models, a vicious walk model and a flow model, on an isotropic regular lattice and on the rectangular honeycomb lattice of various sizes. in both cases, the dynamics   is governed by the nature of the frustration of the particle movements. by simulations,   we have found the approximate functional form of the frustration probability, and peculiar anomalous diffusions in their time - averaged mean square displacements in the flow model.   the relations to other existing statistical models and possible extensions of the models are also discussed.
we discuss images of the central @xmath010 kpc ( in projection ) of the galaxy merger ngc 6240 at h and k bands, taken with the nirc2 narrow camera on keck ii using natural guide star adaptive optics.   we detect 28 star clusters in the nirc2 images, of which only 7 can be seen in the similar - spatial - resolution, archival wfpc2 planetary camera data at either b or i bands. combining the nirc2 narrow camera pointings with wider nicmos nic2 images taken with the f110w, f160w, and f222 m filters,   we identify a total of 32 clusters that are detected in at least one of these 5 infrared ( @xmath1 ) bandpasses. by comparing to instantaneous burst, stellar population synthesis models @xcite  , we estimate that most of the clusters are consistent with being @xmath015 myr old and have photometric masses ranging from @xmath2 to @xmath3.   the total contribution to the star formation rate ( sfr ) from these clusters is approximately @xmath4, or @xmath010% of the total sfr in the nuclear region.   we use these newly discovered clusters to estimate the extinction toward ngc 6240 s double nuclei, and find values of @xmath5 as high as 14 magnitudes along some sightlines, with an average extinction of @xmath6 mag toward sightlines within @xmath7of the double nuclei.
solar neutrino physics enters a stage of precision measurements. in this connection we present a precise analytic description of the neutrino conversion in the context of lma msw solution of the solar neutrino problem. using the adiabatic perturbation theory we derive an analytic formula for the @xmath0 survival probability which takes into account the non - adiabatic corrections and the regeneration effect inside the earth.   the probability is averaged over the neutrino production region.   we find that the non - adiabatic corrections are of the order @xmath1.   using the formula for the earth regeneration effect we discuss features of the zenith angle dependence of the @xmath0 flux. in particular, we show that effects of small structures at the surface of the earth can be important.   + * toward precision measurements in solar neutrinos *    p. c. de holanda@xmath2, wei liao@xmath3 and a. yu.   smirnov@xmath4 +   + _ @xmath3 ictp, strada costiera 11, 34014 trieste, italy _ + _   @xmath5 institute for nuclear research of russian academy of sciences, moscow 117312, russia _
we study the structure of shocks in clumpy media, using a multifluid formalism.   as expected, shocks broaden as they weaken : for sufficiently weak shocks, no viscous subshock appears in the structure.   this has significant implications for the survival of dense clouds in regions overrun by shocks in a wide range of astrophysical circumstances, from planetary nebulae to the nuclei of starburst galaxies.   cite#1#2(@tempswa # 2 # 1 )    # 1( )  = " 8000  = |#1_#1    # 1@xmath0 # 1#2 # 1#1    # 1#2#1@xmath1        hydrodynamics  shock waves   ism : clouds  ism : globules  ism : kinematics and dynamics
we investigate the large - time scaling regimes arising from a variety of metastable structures in a chain of ising spins with both first- and second - neighbor couplings while subject to a kawasaki dynamics.   depending on the ratio and sign of these former, different dynamic exponents are suggested by finite - size scaling analyses of relaxation times. at low but   nonzero - temperatures these are calculated via exact diagonalizations of the evolution operator in finite chains under several activation barriers. in the absence of metastability the dynamics   is always diffusive.
in this article, we investigate the status of the homomorphism preservation property amongst restricted classes of finite relational structures and algebraic structures.   we show that there are many homomorphism - closed classes of finite lattices that are definable by a first - order sentence but not by existential positive sentences, demonstrating the failure of the homomorphism preservation property for lattices at the finite level.   in contrast to the negative results for algebras, we establish a finite - level relativised homomorphism preservation theorem in the relational case. more specifically,   we give a complete finite - level characterisation of first - order definable finitely generated anti - varieties relative to classes of relational structures definable by sentences of some general forms.   when relativisation is dropped, this gives a fresh proof of atserias s characterisation of first - order definable constraint satisfaction problems over a fixed template, a well known special case of rossman s finite homomorphism preservation theorem.
we present the first measurement of the stellar kinematics in the polar ring of ngc  4650a.   there is well defined rotation, with the stars and gas rotating in the same direction, and with similar amplitude.   the gaseous and stellar kinematics suggest an approximately flat rotation curve, providing further support for the hypothesis that the polar material resides in a disk rather than in a ring.   the kinematics of the emission line gas at and near the center of the s0 suggests that the polar disk lacks a central hole.   we have not detected evidence for two, equal mass, counterrotating stellar polar streams, as is predicted in the resonance levitation model proposed by tremaine & yu. a merger seems the most likely explanation for the structure and kinematics of ngc  4650a.
neural responses are highly variable, and some portion of this variability arises from fluctuations in modulatory factors that alter their gain, such as adaptation, attention, arousal, expected or actual reward, emotion, and local metabolic resource availability. regardless of their origin, fluctuations in these signals can confound or bias the inferences that one derives from spiking responses.   recent work demonstrates that for sensory neurons, these effects can be captured by a modulated poisson model, whose rate is the product of a stimulus - driven response function and an unknown modulatory signal . here, we extend this model, by incorporating explicit modulatory elements that are known ( specifically, spike - history dependence, as in previous models  ), and by constraining the remaining latent modulatory signals to be smooth in time.   we develop inference procedures for fitting the entire model, including hyperparameters, via evidence optimization , and apply these to simulated data, and to responses of ferret auditory midbrain and cortical neurons to complex sounds.   we show that integrating out the latent modulators yields better ( or more readily - interpretable ) receptive field estimates than a standard poisson model.   conversely, integrating out the stimulus dependence yields estimates of the slowly - varying latent modulators.
we report state - of - the - art quantum monte carlo calculations of the singlet @xmath0 ( co ) vertical excitation energy in the acrolein molecule, extending the recent study of bouaba _ et al. _ [ j. chem.   phys. * 130 *, 114107 ( 2009 ) ].   we investigate the effect of using a slater basis set instead of a gaussian basis set, and of using state - average versus state - specific complete - active - space ( cas ) wave functions, with or without reoptimization of the coefficients of the configuration state functions ( csfs ) and of the orbitals in variational monte carlo ( vmc ).   it is found that, with the slater basis set used here, both state - average and state - specific cas(6,5 ) wave functions give an accurate excitation energy in diffusion monte carlo ( dmc ), with or without reoptimization of the csf and orbital coefficients in the presence of the jastrow factor.   in contrast, the cas(2,2 ) wave functions require reoptimization of the csf and orbital coefficients to give a good dmc excitation energy.   our best estimates of the vertical excitation energy are between 3.86 and 3.89 ev.
we introduce from an experimental point of view the main concepts of fluctuation theorems for work, heat and entropy production in out of equilibrium systems  . we will discuss the important difference between the applications of these concepts to stochastic systems and to a second class of systems ( chaotic systems ) where the fluctuations are induced either by chaotic flows or by fluctuating driving forces.   we will mainly analyze the stochastic systems using the measurements performed in two experiments : a ) a harmonic oscillator driven out of equilibrium by an external force b ) a colloidal particle trapped in a time dependent double well potential.   we will rapidly describe some consequences of fluctuation theorems and some useful applications to the analysis of experimental data. as an example   the case of a molecular motor will be analyzed in some details.   finally we will discuss the problems related to the applications of fluctuation theorems to chaotic systems.
the mortality related to cervical cancer can be substantially reduced through early detection and treatment. however  , current detection techniques, such as pap smear and colposcopy, fail to achieve a concurrently high sensitivity and specificity.   _ in vivo _ fluorescence spectroscopy is a technique which quickly, _   non - invasively _ and quantitatively probes the biochemical and morphological changes that occur in pre - cancerous tissue.   a multivariate statistical algorithm was used to extract clinically useful information from tissue spectra acquired from 361 cervical sites from 95 patients at 337, 380 and 460 nm excitation wavelengths.   the multivariate statistical analysis was also employed to reduce the number of fluorescence excitation - emission wavelength pairs required to discriminate healthy tissue samples from pre - cancerous tissue samples.   the use of connectionist methods such as multi layered perceptrons, radial basis function networks, and ensembles of such networks was investigated.   rbf ensemble algorithms based on fluorescence spectra potentially provide automated, and near real - time implementation of pre - cancer detection in the hands of non - experts.   the results are more reliable, direct and accurate than those achieved by either human experts or multivariate statistical algorithms.    0.3 in 6.0 in -0.3 in 8.7 in 0.2 in
this article is intended to provide a pedagogical account of issues related to, and recent work on, gravitational waves from coalescing compact binaries ( composed of neutron stars and/or black holes ).   these waves are the most promising for kilometer - size interferometric detectors such as ligo and virgo.   topics discussed include : interferometric detectors and their noise ; coalescing compact binaries and their gravitational waveforms ; the technique of matched filtering for signal detection and measurement ; waveform calculations in post - newtonian theory and in the black - hole perturbation approach ; and the accuracy of the post - newtonian expansion.   _ contents : _ 1.  introduction.   2.  interferometric detectors.   3.  detector noise.   4.  more about detector noise.   5.  coalescing compact binaries.   6.   waveform according to the quadrupole formula  . 7.   matched filtering.   8.   the signal - to - noise ratio.   9.  signal detection. 10.  signal measurement.   11.   waveform calculations : post - newtonian theory.   12.   waveform to second post - newtonian order. 13.   waveform calculations : perturbation theory.   14.   luminosity from the perturbation approach. 15.   accuracy of the post - newtonian expansion.   16.  conclusion.   8.5truein 6.5truein
this paper addresses the problem of binaural localization of a single speech source in noisy and reverberant environments. in practice, this response is contaminated by noise and reverberations. the direct - path relative transfer function   ( dp - rtf ) is defined as the ratio between the direct - path acoustic transfer function of the two channels.   we propose a method to estimate the dp - rtf from the noisy and reverberant microphone signals in the short - time fourier transform domain.   first, the convolutive transfer function approximation is adopted to accurately represent the impulse response of the sensors in the stft domain.   second, the dp - rtf is estimated by using the auto- and cross - power spectral densities at each frequency and over multiple frames. in the presence of stationary noise, an inter - frame spectral subtraction algorithm is proposed, which enables to achieve the estimation of noise - free auto- and cross - power spectral densities. finally, the estimated dp - rtfs are concatenated across frequencies and used as a feature vector for the localization of speech source.   experiments with both simulated and real data show that the proposed localization method performs well, even under severe adverse acoustic conditions, and outperforms state - of - the - art localization methods under most of the acoustic conditions.   binaural source localization, direct - path relative transfer function, inter - frame spectral subtraction.
after the discovery of the 125 gev scalar boson with gauge properties similar to the standard model higgs, the search for beyond the sm interactions will focus on studying the discovered particles coupling properties more precisely and shedding light on the relation of fermion masses with the electroweak vacuum.   the large mass of the top quark and the sm - predicted order one top yukawa coupling is a natural candidate for bsm physics, though experimentally challenging to constrain. in this paper  , we argue that investigating angular correlations in @xmath0 production provides an excellent handle to constrain the top yukawa coupling @xmath1 via direct measurements, even when we focus on rare exclusive final states.   we perform a hadron - level analysis and show that we may expect to constrain @xmath2 at 95%-99% confidence level at the high luminosity lhc using semi - leptonic top decays and @xmath3 alone, by employing a two - channel measurement approach.
we have used optical echelle spectra along with rosat and asca x - ray spectra to test the hypothesis that the southern portion of the n44 x - ray bright region is the result of a blowout structure.   three pieces of evidence now support this conclusion.   first, the filamentary optical morphology corresponding with the location of the x - ray bright south bar suggests the blowout description ( chu et  al.1993 ).   second, optical echelle spectra show evidence of high velocity ( 90  km  sec@xmath0 ) gas in the region of the blowout.   third, x - ray spectral fits show a lower temperature for the south bar than the main superbubble region of shell  1.   such a blowout can affect the evolution of the superbubble and explain some of the discrepancy discussed by oey & massey ( 1995 ) between the observed shell diameter and the diameter predicted on the basis of the stellar content and weaver et al.s ( 1977 ) pressure - driven bubble model.    #   1#2#1@xmath1    -0.5 in 6.5 in
the critical behavior for the light nuclei with a@xmath0 has been investigated experimentally by the nimrod multi - detectors.   the wide variety of observables indicate the critical point has been reached in the disassembly of hot nuclei at an excitation energy of 5.6@xmath10.5 mev / u.
we consider localized qubits evolving around a black hole following a quantum adiabatic dynamics. we develop a geometric structure ( based on fibre bundles ) permitting to describe the quantum states of a qubit and the spacetime geometry in a single framework.   the quantum decoherence induced by the black hole on the qubit is analysed in this framework ( the role of the dynamical and geometric phases in this decoherence is treated ), especially for the quantum teleportation protocol when one qubit falls to the event horizon.   a simple formula to compute the fidelity of the teleportation is derived.   the case of a schwarzschild black hole is analysed.
credit estimation and bankruptcy prediction methods have utilized altman s z - score method for the last several years.   it is reported in many studies that z - score is sensitive to changes in accounting figures.   researchers have proposed different variations to conventional z - score that can improve the prediction accuracy. in this paper  , we develop a new multivariate nonlinear model for computing the z - score.   in addition, we develop a new credit risk index by fitting a pearson type 3 distribution to the transformed financial ratios.   the results of our study have shown that the new z - score can predict the bankruptcy with an accuracy of @xmath0 as compared to @xmath1 by altman s z - score.   also, the discriminate analysis revealed that the new transformed financial ratios could predict the bankruptcy probability with an accuracy of @xmath2 as compared to @xmath3 using the weights of altman s z - score.
the interstellar thick disks of galaxies contain not only gas, but significant quantities of dust.   most of our knowledge of extraplanar dust in disk galaxies comes from direct broadband optical imaging of these systems, wherein the dust is identified due to the irregular extinction it produces against the thick disk and bulge stars.   this observational technique is sensitive to only the most dense material, and we argue much of the material identified in this way traces a cold phase of the interstellar thick disks in galaxies. the presence of a cold, dense phase likely implies the interstellar pressures in the thick disks of spiral galaxies can be quite high.   this dense phase of the interstellar medium may also fueling thick disk star formation, and h@xmath0  observations are now revealing h@xmath1ii  regions around newly - formed ob stars associations in several galaxies.   we argue that the large quantities of dust and the morphologies of the structures traced by the dust imply that much of the extraplanar material in disk galaxies must have been expelled from the underlying thin disk.
we study the spin - spin coupling between two single - electron quantum dots due to the coulomb and spin - orbit interactions, in the absence of tunneling between the dots.   we find an anisotropic @xmath0 spin - spin interaction that is proportional to the zeeman splitting produced by the external magnetic field.   this interaction is studied both in the limit of weak and strong coulomb repulsion with respect to the level spacing of the dot.   the interaction is found to be a non - monotonic function of inter - dot distance @xmath1 and external magnetic field, and, moreover, vanishes for some special values of @xmath1 and/or magnetic field orientation.   this mechanism thus provides a new way to generate and tune spin interaction between quantum dots.   we propose a scheme to measure this spin - spin interaction based on the spin - relaxation - measurement technique.
we present optical photometry of the eclipsing supersoft source, cal  87.   these observations comprise long term data accumulated as a by - product of the macho project, and high speed white light photometry of a single eclipse.   we ( _ i _ ) derive an improved ephemeris of @xmath0 hjd @xmath1 for the time of minimum light, ( _ ii _ ) find the eclipse structure to be stable over a period of @xmath2years, and ( _ iii _ ) investigate the colour variation as a function of orbital phase.   the resolution afforded by the high speed nature of the white light observations enables us to see new structure in the light curve morphology.    #   1to 0pt#1    accretion, accretion discs  binaries : close  binaries : spectroscopic  stars : individual : cal  87  magellanic clouds  x - rays : stars
what is the higgs boson telling us? what else is there, maybe supersymmetry and/or dark matter?   how do we find it? these are now the big questions in collider physics that i discuss in this talk, from a personal point of view.   lhc, higgs boson, supersymmetry, dark matter
we propose a variational wave function for the ground state of the magnetic heavy fermion ( hf ) systems, in which both the kondo and the rkky interactions are variationally incorporated and the local f - orbital state exists as a linear combination of a full local moment state and a fully compensated state ( mixed moment state ).   we describe the mechanism for the mixed moment ground state based on the large - n treatment of the kondo lattice hamiltonian added with rkky interaction. with the mixed moment ground state   we can explain several puzzling experiments in magnetic hf compounds such as a small value of local moment, coexistence of the antiferromagnetic ( afm ) and the paramagnetic ( pm ) phases, local quantum criticality, etc.    2
the quark - antiquark potential is constructed by making use of a new analytic running coupling in qcd.   this running coupling arises under `` analytization '' of the renormalization group equation.   the rising behavior of the quark - antiquark potential at large distances, which provides the quark confinement, is shown explicitly. at small distances, the standard behavior of this potential originating in the qcd asymptotic freedom   is revealed.   the higher loop corrections and the scheme dependence of the approach are briefly discussed.
we analyze in detail a previous proposal by dvali and gmez that black holes could be treated as consisting of a bose - einstein condensate of gravitons. in order to do   so we extend the einstein - hilbert action with a chemical potential - like term, thus placing ourselves in a grand - canonical ensemble. the form and characteristics of this chemical potential - like piece   are discussed in some detail.   after this, we proceed to expand the ensuing equations of motion up to second order around the classical schwarzschild metric so that some non - linear terms in the metric fluctuation are kept.   we argue that the resulting equations could be interpreted as the gross - pitaevskii equation describing a graviton bose - einstein condensate trapped by the black hole gravitational field.   next we search for solutions and, modulo some very plausible assumptions, we find out that the condensate vanishes outside the horizon but is non - zero in its interior.   based on hints from a numerical integration of the equations we formulate an ansatz and eventually find an exact non - trivial solution for a mean - field wave - function describing the graviton bose - einstein condensate in the black hole interior.   based on this we can rederive some of the relations involving the number of gravitons @xmath0 and the black hole characteristics, summarized in its schwarzschild radius, along the lines suggested by dvali and gmez.   these relations are parametrized by a single parameter a dimensionless chemical potential.   august 2016    iccub-16 - 032
typical quantum communication schemes are such that to achieve perfect decoding the receiver must share a reference frame with the sender. indeed, if the receiver only possesses a bounded - size quantum token of the sender s reference frame, then the decoding is imperfect, and we can describe this effect as a noisy quantum channel.   we seek here to characterize the performance of such schemes, or equivalently, to determine the effective decoherence induced by having a bounded - size reference frame.   we assume that the token is prepared in a special state that has particularly nice group - theoretic properties and that is near - optimal for transmitting information about the sender s frame.   we present a decoding operation, which can be proven to be near - optimal in this case, and we demonstrate that there are two distinct ways of implementing it ( corresponding to two distinct kraus decompositions ). in one,   the receiver measures the orientation of the reference frame token and reorients the system appropriately. in the other  , the receiver extracts the encoded information from the virtual subsystems that describe the relational degrees of freedom of the system and token.   finally, we provide explicit characterizations of these decoding schemes when the system is a single qubit and for three standard kinds of reference frame : a phase reference, a cartesian frame ( representing an orthogonal triad of spatial directions ), and a reference direction ( representing a single spatial direction ).
time - dependent speckle pattern of paraelectric barium titanate observed in a soft x - ray laser pump - probe measurement is theoretically investigated as a correlated optical response to the pump and probe pulses.   the scattering probability is calculated based on a model with coupled soft x - ray photon and ferroelectric phonon mode.   it is found that the speckle variation is related with the relaxation dynamics of ferroelectric clusters created by the pump pulse.   additionally, critical slowing down of cluster relaxation arises on decreasing temperature towards the paraelectric - ferroelectric transition temperature.   relation between critical slowing down, local dipole fluctuation and crystal structure are revealed by quantum monte carlo simulation.
charged stars have the potential of becoming charged black holes or even naked singularities.   it is presented a set of numerical solutions of the tolman - oppenheimer - volkov equations that represents spherical charged compact stars in hydrostatic equilibrium.   the stellar models obtained are evolved forward in time integrating the einstein - maxwell field equations.   it is assumed an equation of state of a neutron gas at zero temperature.   the charge distribution is taken as been proportional to the rest mass density distribution.   the set of solutions present an unstable branch, even with charge to mass ratios arbitrarily close to the extremum case.   it is performed a direct check of the stability of the solutions under strong perturbations, and for different values of the charge to mass ratio.   the stars that are in the stable branch oscillates and do not collapse, while models in the unstable branch collapse directly to form black holes. stars with a charge greater or equal than the extreme value explode.   when a charged star is suddenly discharged, it do nt necessarily collapse to form a black hole. a non - linear effect that gives rise to the formation of an external shell of matter ( see ghezzi and letelier 2005 ), is negligible in the present simulations.   the results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.
it is a challenge to synthesize graphene nanoribbons ( gnrs ) with narrow widths and smooth edges in large scale.   our first principles study on the hydrogenation of gnrs shows that the hydrogenation starts from the edges of gnrs and proceeds gradually toward the middle of the gnrs so as to maximize the number of carbon - carbon @xmath0-@xmath0 bonds.   furthermore, the partially hydrogenated wide gnrs have similar electronic and magnetic properties as those of narrow gnrs.   therefore, it is not necessary to directly produce narrow gnrs for realistic applications because partial hydrogenation could make wide gnrs `` narrower ''.
we show that hard - scattering factorization is violated in the production of high-@xmath0 hadrons in hadron - hadron collisions, in the case that the hadrons are back - to - back, so that @xmath1 factorization is to be used.   the explicit counterexample that we construct is for the single - spin asymmetry with one beam transversely polarized.   the sivers function needed here has particular sensitivity to the wilson lines in the parton densities.   we use a greatly simplified model theory to make the breakdown of factorization easy to check explicitly.   but the counterexample implies that standard arguments for factorization fail not just for the single - spin asymmetry but for the unpolarized cross section for back - to - back hadron production in qcd in hadron - hadron collisions.   this is unlike corresponding cases in @xmath2 annihilation, drell - yan, and deeply inelastic scattering.   moreover, the result endangers factorization for more general hadroproduction processes.
we have obtained adaptive optics, high spatial resolution ( 0.15 arcsecond ) k - band spectra and images of the region around the two active nuclei in ngc 6240 which show the presence of circumnuclear shocks.   the data are consistent with the thermal excitation mechanism being the dominant one in the nuclear region.   uv fluorescence and associative detachment may also contribute to the fraction of the energy emitted through molecular hydrogen transitions.   the near - ir continuum emission appears closely associated with the two active nuclei.   the morphological similarities between the near - ir images and the chandra x - ray images indicate the same mechanisms may be responsible for the emission in near - ir and x - ray band.
we solve the isoperimetric problem in the lens spaces with large fundamental group.   namely, we prove that the isoperimetric surfaces are geodesic spheres or tori of revolution about geodesics.   we also show that the isoperimetric problem in @xmath0 and @xmath1 follows from the proof of the willmore conjecture by marques and neves.
in this paper we study the detectability of @xmath0-rays from dark matter annihilation in the subhalos of the milky way by the satellite - based experiments, egret and glast.   we work in the frame of supersymmetric extension of the standard model and assume the lightest neutralino being the dark matter particles. based on the n - body simulation of the evolution of dark matter subhalos   we first calculate the average intensity distribution of this new class of @xmath0-ray sources by neutralino annihilation.   it is possible to detect these @xmath0-ray sources by egret and glast.   conversely, if these sources are not detected the nature of the dark matter particls will be constrained by these experiments, depending, however, on the uncertainties of the subhalo profile.
in their study of the evolution of galaxies within clusters, butcher and oemler discovered evidence for a strong evolution in star - formation rate with redshift.   later studies confirmed this conclusion and uncovered several aspects of the effect : photometric, spectroscopic, and morphological.   this article reviews a broad sample of these works and discusses selection effects, biases, and driving mechanisms that might be responsible for the changes in star - formation rate.   = 2em = 15.5 cm = 22.6 cm = -1.0 cm = 0.5 cm = 0.5 cm    department of physics, university of queensland, brisbane, queensland 4072, australia +   + pimbblet@physics.uq.edu.au +    * keywords : * galaxies : evolution  galaxies : clusters : general  cosmology : observations
an isolated massive star can blow a bubble, while a group of massive stars can blow superbubbles. in this paper, we examine three intriguing questions regarding bubbles and superbubbles : ( 1 ) why do nt we see interstellar bubbles around every o star? ( 2 ) how hot are the bubble interiors? and   ( 3 ) what is going on at the hot / cold gas interface in a bubble?
we investigate the space of functions in which the bfkl kernel acts. for the amplitudes which describe the scattering of colorless projectiles it is convenient to define, in transverse coordinates, the mbius space in which the solutions to the bfkl equation vanish as the coordinates of the two reggeized gluons coincide.   however, in order to fulfill the bootstrap relation for the bfkl kernel it is necessary to modify the space of functions.   we define and investigate a new space of functions and show explicitly that the bootstrap relation is valid for the corresponding spectral form of the kernel.   we calculate the generators of the resulting deformed representation of the @xmath0 algebra.   desy 05 - 103 issn 0418 - 9833 +     * deformed spectral representation of the bfkl kernel and the bootstrap for gluon reggeization * +      + _ @xmath1ii.   institut fr theoretische physik, universitt hamburg, + luruper chaussee 149, d-22761 hamburg, germany _ + _   @xmath2 petersburg nuclear physics institute + gatchina, 188 300 st.petersburg, russia _ + _ @xmath3 dipartimento di fisica - universit di bologna and infn - sezione di bologna, + via irnerio 46, 40126 bologna, italy _
we study one- and two - dimensional models which undergo a transition between active and absorbing phases.   the transition point in these models is of novel type : jump of the order parameter coincides with its power - law singularity.   some arguments supported by monte carlo simulations prompted us to predict the exact location of the transition point.   both models possess gauge - like symmetry.
there are some discrepancies in the results on energy spectrum from yakutsk, agasa, and hires experiments. in this work differential energy spectrum of primary cosmic rays based on the yakutsk eas array data   is presented. for the largest events values of @xmath0 and axes   coordinates have been obtained using revised lateral distribution function.   simulation of converter s response at large distances showed no considerable underestimation of particle density.   complex shape of spectrum in region of @xmath1  ev is confirmed.   after adjustment of parameters and additional exposition at the yakutsk array there are three events with energy @xmath2  ev.
it is shown how to implement quantum feedback and probabilistic error correction in an open quantum system consisting of a single atom, with ground- and excited - state zeeman structure, in a driven two - mode optical cavity.   the ground state superposition is manipulated and controlled through conditional measurements and external fields, which shield the coherence and correct quantum errors.   modeling of an experimentally realistic situation demonstrates the robustness of the proposal for realization in the laboratory.
we investigate the influence of blending on the cepheid distance scale using two local group galaxies, m31 and m33. blending leads to systematically low distances to galaxies observed with the hst, and therefore to systematically high estimates of @xmath0.   high - resolution hst images are compared to our ground - based data, obtained as part of the direct project, for a sample of 22 cepheids in m31 and 102 cepheids in m33. for a sample of 22 cepheids in m31,   the average ( median ) flux contribution from luminous companions not resolved on the ground - based images in the @xmath1-band, @xmath2, is about 19% ( 12% ) of the flux of the cepheid. for 102 cepheids in m33 the average ( median ) values of @xmath2,   @xmath3, @xmath4 are 23% ( 13% ), 28% ( 20% ), 28% ( 15% ). for 64 cepheids in m33 with periods in excess of 10 days the average ( median )   @xmath2, @xmath3, @xmath4 are 16% ( 7% ), 23% ( 12% ), 20% ( 10% ).   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we have measured the rotational velocities ( ) of the mass donors in a number of dtype symbiotic stars, using the cross - correlation function method.   four from five d symbiotic stars with known, appeared to be very fast rotators compared with the catalogues of  for the corresponding spectral types.   at least three of these stars rotate at a substantial fraction ( @xmath0 ) of the critical velocity.   this means that at least in dtype ss the cool components rotate faster than isolated giants.   if these binary stars are synchronized, their orbital periods should be relatively short ( 4 - 60 days ).   we also briefly discuss the possible origin of the rapid rotation and its connection with mass loss and dust formation.       stars : binaries : symbiotic  stars : rotation  stars : late type
in this paper we theoretically study electromagnetic reflection, transmission, and scattering properties of periodic and random arrays of particles which exhibit both electric - mode and magnetic - mode resonances.   we compare the properties of regular and random grids and explain recently observed dramatic differences in resonance broadening in the electric and magnetic modes of random arrays.   we show that randomness in the particle positioning influences equally on the scattering loss from both electric and magnetic dipoles, however, the observed resonance broadening can be very different depending on the absorption level in different modes as well as on the average electrical distance between the particles.   the theory is illustrated by an example of a planar metasurface composed of cut - wire pairs.   we show that in this particular case at the magnetic resonance the array response is almost not affected by positioning randomness due to lower frequency and higher absorption losses in that mode.   the developed model allows predictions of behavior of random grids based on the knowledge of polarizabilities of single inclusions.
we report @xmath0 pair yield from charm decay measured between midrapidity electrons ( @xmath1 and @xmath2  gev/@xmath3 ) and forward rapidity muons ( @xmath4 and @xmath5  gev/@xmath3 ) as a function of @xmath6 in both @xmath7@xmath8@xmath7 and in @xmath9+au collisions at @xmath10  gev. comparing the @xmath7@xmath8@xmath7 results with several different models, we find the results are consistent with a total charm cross section @xmath11 538 @xmath12 46 ( stat ) @xmath12 197  ( data  syst ) @xmath12 174  ( model  syst ) @xmath13b. these generators also indicate that the back - to - back peak at @xmath14 is dominantly from the leading order contributions ( gluon fusion ), while higher order processes ( flavor excitation and gluon splitting ) contribute to the yield at all @xmath6.   we observe a suppression in the pair yield per collision in @xmath9+au.   we find the pair yield suppression factor for @xmath15 rad is @xmath16 = 0.433 @xmath12 0.087 ( stat ) @xmath12 0.135 ( syst ), indicating cold nuclear matter modification of @xmath17 pairs.
we discuss the quasiclassical approximation for the equations of motions of a nonlinear chain of phonons and electrons having phonon mediated hopping. describing the phonons and electrons as even and odd grassmannian functions and using the continuum limit   we show that the equations of motions lead to a zakharov - like system for bosonic and fermionic fields.   localised and nonlocalised solutions are discussed using the hirota bilinear formalism.   nonlocalised solutions turn out to appear naturally for any choice of wave parameters.   the bosonic localised solution has a fermionic dressing while the fermionic one is an oscillatory localised field.   they appear only if some constraints on the dispersion are imposed. in this case   the density of fermions is a strongly localised travelling wave.   also it is shown that in the multiple scales approach the emergent equation is _   linear_. only for the resonant case we get a nonlinear fermionic yajima - oikawa system.   physical implications are discussed.
phase transformations such as freezing typically start with heterogeneous nucleation.   heterogeneous nucleation near a wetting transition, of a crystalline phase is studied.   the wetting transition occurs at or near a vapour - liquid transition which occurs in a metastable fluid.   the fluid is metastable with respect to crystallisation, and it is the crystallisation of this fluid phase that we are interested in. at a wetting transition a thick layer of a liquid phase forms at a surface in contact with the vapour phase.   the crystalline nucleus is then immersed in this liquid layer, which reduces the free energy barrier to nucleation and so dramatically increases the nucleation rate.   the variation in the rate of heterogeneous nucleation close to wetting transitions is calculated for systems in which the longest - range forces are dispersion forces.
early - type galaxies are characterized by many scaling relations.   one of them, the so - called fundamental plane is a relatively tight correlation between three variables, and has resisted a clear physical understanding despite many years of intensive research. here, we show that the correlation between the three variables of the fundamental plane can be the artifact of the effect of another parameter influencing all, so that the fundamental plane may be understood as a confounding correlation.   indeed, the complexity of the physics of galaxies and of their evolution suggests that the main confounding parameter must be related to the level of diversification reached by the galaxies.   consequently, many scaling relations for galaxies are probably evolutionary correlations.       galaxies : fundamental parameters - methods : statistical - galaxies : evolution - galaxies : formation -
uncertainties of the mssm predictions are due to an unknown susy breaking mechanism. to reduce these uncertainties,   one usually imposes constraints on the mssm parameter space.   recently, two new constraints became available, both from astrophysics : wmap precise measurement of the amount of the dark matter in the universe and egret data on an excess in diffuse gamma ray flux.   being interpreted as a manifestation of supersymmetry these data lead to severe constraints on parameter space and single out a very restricted area.   the key feature of this area is the splitting of light gauginos from heavy squarks and sleptons.   we study the phenomenological properties of this scenario, in particular, the cross - sections of superparticle production, their decay patterns and signatures for observation at hadron colliders, tevatron and lhc.   we found that weakly interacting particles in this area are very light so that the cross - sections may reach fractions of a pb with jets and/or leptons as final states accompanied by missing energy taken away by light neutralino with a mass around 100 gev.
the influence of hole - hole propagation in addition to the conventional particle - particle propagation, on the energy per nucleon and the momentum distribution is investigated.   the results are compared to the brueckner - hartree - fock ( bhf ) calculations with a continuous choice and conventional choice for the single - particle spectrum.   the bethe - goldstone equation has been solved using realistic @xmath0 interactions. also, the structure of nucleon self - energy in nuclear matter is evaluated.   all the self - energies are calculated self - consistently.   starting from the bhf approximation without the usual angle - average approximation, the effects of hole - hole contributions and a self - consistent treatment within the framework of the green function approach are investigated. using the self - consistent self - energy, the hole and particle self - consistent spectral functions including the particle - particle and hole - hole ladder contributions in nuclear matter   are calculated using realistic @xmath0 interactions.   we found that, the difference in binding energy between both results, i.e. bhf and self - consistent green function, is not large.   this explains why is the bhf ignored the 2h1p contribution.    * and e.m.   darwish *    nuclear matter, green function, spectral function, binding energy.
a scheme is proposed, that allows one for performing homodyne detection of the matter - wave field of ultracold bosonic atoms.   it is based on a pump - probe lasers setup, that both illuminates a bose - einstein condensate, acting as reference system, and a second ultracold gas, composed by the same atoms but in a quantum phase to determine.   photon scattering outcouples atoms from both systems, which then propagate freely. under appropriate conditions,   when the same photon can either be scattered by the bose - einstein condensate or by the other quantum gas, both flux of outcoupled atoms and scattered photons exhibit oscillations, whose amplitude is proportional to the condensate fraction of the quantum gas.   this setup allows one, for instance, to perform thermometry of a condensate or to monitor the mott - insulator / superfluid phase transition in optical lattices, and can be extended in order to measure the first - order correlation function of a quantum gas.   the dynamics here discussed make use of the entanglement between atoms and photons, which is established by the scattering process, in order to access detailed information on the quantum state of matter.
the quasi - satellite ( qs ) phenomenon makes two celestial bodies to fly near each other @xcite and that effect can be used also to make artificial satellites move in tandem.   we consider formation flight of two or three satellites in low eccentricity near earth orbits. with the help of weak ion thrusters it is possible to accomplish tandem flight. with ion thrusters   it is also possible to mimic many kinds of mutual force laws between the satellites.   we found that both a constant repulsive force or an attractive force that decreases with the distance are able to preserve the formation in which the eccentricities cause the actual relative motion and the weak thrusters keep the mean longitude difference small.   initial values are important for the formation flight but very exact adjustment of orbital elements is not important.   simplicity is one of our goals in this study and this result is achieved at least in the way that, when constant force thrusters are used, the satellites only need to detect the directions of the other ones to fly in tandem.   a repulsive acceleration of the order of @xmath0 times the earth attraction, is enough to effectively eliminate the disruptive effects of all the perturbations at least for a timescale of years.       celestial mechanics  planets and satellites
the authors study the short - time dynamics of helix - forming polypeptide chains using an all - atom representation of the molecules and an implicit solvation model to approximate the interaction with the surrounding solvent.   the results confirm earlier observations that the helix - coil transition in proteins can be described by a set of critical exponents.   the high statistics of the simulations allows the authors to determine the exponents values with increased precision and support universality of the helix - coil transition in homopolymers and ( helical ) proteins.
we review the recent multifrequency studies of galactic black hole binaries, aiming at revealing the underlying emission processes and physical properties in these systems.   the optical and infrared observations are important for determining their system parameters, such as the companion star type, orbital period and separation, inclination angle and the black hole mass.   the radio observations are useful for studying high energy electron acceleration process, jet formation and transport.   x - ray observations can be used to probe the inner accretion disk region in order to understand the fundamental physics of the accretion disk in the strongest gravitational field and the properties of the black hole.   future higher sensitivity and better resolution instrumentation will be needed to answer the many fundamental questions that have arisen.
the approximate atomic self - interaction corrections ( asic ) method to density functional theory is put to the test by calculating the exchange interaction for a number of prototypical materials, critical to local exchange and correlation functionals.   asic total energy calculations are mapped onto an heisenberg pair - wise interaction and the exchange constants @xmath0 are compared to those obtained with other methods. in general the asic scheme drastically improves the bandstructure, which for almost all the cases investigated resemble closely available photo - emission data.   in contrast the results for the exchange parameters are less satisfactory.   although asic performs reasonably well for systems where the magnetism originates from half - filled bands, it suffers from similar problems than those of lda for other situations.   in particular the exchange constants are still overestimated.   this reflects a subtle interplay between exchange and correlation energy, not captured by the asic.
the structural transformation of multiferroic eutio@xmath0 has been intensively investigated by synchrotron x - ray diffraction at pressures up to 50.3 gpa and temperatures from 50 to 500 k. an antiferrodistortive phase transition from cubic _   pm-3 m _ to tetragonal _   i4/mcm _ space group has been observed, identical to the one that has been previously explored at ambient pressure and low temperatures.   several compression / decompression cycles at different temperatures have been carried out to accurately map the transition, and as a result a p - t phase diagram for eutio@xmath0 has been constructed. the observed phase transition exhibits many similarities with isostructural srtio@xmath0, although the absence of magnetoelectric interactions in the latter accounts for the different phase boundaries between the two materials.    0.7 cm
we discuss the local density approximation approach to calculating the ground state energy of a one - dimensional fermi gas containing a single impurity, and compare the results with exact numerical values that we have for up to 11 particles for general interaction strengths and up to 30 particles in the strongly interacting case.   we also calculate the contact coefficient in the strongly interacting regime.   the different theoretical predictions are compared to recent experimental results with few - atom systems.   firstly, we find that the local density approximation suffers from great ambiguity in the few - atom regime, yet it works surprisingly well for some models.   secondly, we find that the strong interaction theories quickly break down when the number of particles increase or the interaction strength decreases.
building on work of barker, humpherys, lafitte, rudd, and zumbrun in the shock wave case, we study stability of compressive, or `` shock - like '', boundary layers of the isentropic compressible navier  stokes equations with @xmath0-law pressure by a combination of asymptotic ode estimates and numerical evans function computations.   our results indicate stability for @xmath1 $ ] for all compressive boundary - layers, independent of amplitude, save for inflow layers in the characteristic limit ( not treated ).   expansive inflow boundary - layers have been shown to be stable for all amplitudes by matsumura and nishihara using energy estimates.   besides the parameter of amplitude appearing in the shock case, the boundary - layer case features an additional parameter measuring displacement of the background profile, which greatly complicates the resulting case structure.   moreover, inflow boundary layers turn out to have quite delicate stability in both large - displacement and large - amplitude limits, necessitating the additional use of a mod - two stability index studied earlier by serre and zumbrun in order to decide stability.
we present measurements of the magnetoresistance of long and narrow quasi one - dimensional gold wires containing magnetic iron impurities.   the electron phase coherence time extracted from the weak antilocalisation shows a pronounced plateau in a temperature region of @xmath0mk-@xmath1mk, associated with the phase breaking due to the kondo effect. below the kondo temperature, the phase coherence time increases, as expected in the framework of kondo physics. at much lower temperatures,   the phase coherence time saturates again, in contradiction with standard fermi liquid theory. in the same temperature regime  , the resistivity curve displays a characteristic maximum at zero magnetic field, associated with the formation of a spin glass state.   we argue that the interactions between the magnetic moments are responsible for the low temperature saturation of the phase coherence time.
it has been revealed by mean - field theories and computer simulations that the nature of the collapse transition of a polymer is influenced by its bending stiffness @xmath0. in two dimensions  , a recent analytical work demonstrated that the collapse transition of a partially directed lattice polymer is always first - order as long as @xmath0 is positive [ h.  zhou _ et al.   _, phys.   rev.   lett.  * 97 *, 158302 ( 2006 ) ]. here   we employ monte carlo simulation to investigate systematically the effect of bending stiffness on the static properties of a 2d lattice polymer.   the system s phase - diagram at zero force is obtained.   depending on @xmath0 and the temperature @xmath1, the polymer can be in one of three phases : crystal, disordered globule, or swollen coil.   the crystal - globule transition is discontinuous, the globule - coil transition is continuous. at moderate or high values of @xmath0   the intermediate globular phase disappears and the polymer has only a discontinuous crystal - coil transition.   when an external force is applied, the force - induced collapse transition will either be continuous or discontinuous, depending on whether the polymer is originally in the globular or the crystal phase at zero force.   the simulation results also demonstrate an interesting scaling behavior of the polymer at the force - induced globule - coil transition.
we propose a simple renormalizable grand unified theory based on the @xmath0 gauge symmetry where the neutrino masses are generated at the quantum level through the zee mechanism. in this model   the same higgs needed to correct the mass relation between charged leptons and down - type quarks plays a crucial role to generate neutrino masses.   we show that in this model one can satisfy the constrains coming from the unification of gauge couplings and the mechanism for neutrino masses is discussed in detail.   the predictions for proton decay are discussed in order to understand the testability at current and future experiments such as hyper - kamiokande.   this simple theory predicts a light colored octet which could give rise to exotic signatures at the lhc.
the primary challenge of golf - ng ( global oscillations at low frequency new generation ) is the detection of the low - frequency solar gravity and acoustic modes, as well as the possibility to measure the high - frequency chromospheric modes.   on june 8th 2008, the first sunlight observations with the multichannel resonant golf - ng prototype spectrometer were obtained at the observatorio del teide ( tenerife ).   the instrument performs integrated ( sun - as - a - star ), doppler velocity measurements, simultaneously at eight different heights in the d1 sodium line profile, corresponding to photospheric and chromospheric layers of the solar atmosphere. in order to study its performances, to validate the conceived strategy, and to estimate the necessary improvements, this prototype has been running on a daily basis over the whole summer of 2008 at the observatorio del teide.   we present here the results of the first golf - ng observations, clearly showing the characteristics of the 5-minute oscillatory signal at different heights in the solar atmosphere.   we compare these signals with simultaneous observations from golf / soho and from the mark - i instrument  a node of the bison network, operating at the same site.
we report an _ ab initio _ calculation of the shielding of the nuclear magnetic moment by the bound electron in hydrogen - like ions.   this investigation takes into account several effects that have not been calculated before ( electron self - energy, vacuum polarization, nuclear magnetization distribution ), thus bringing the theory to the point where further progress is impeded by the uncertainty due to nuclear - structure effects.   the qed corrections are calculated to all orders in the nuclear binding strength parameter and, independently, to the leading order in the expansion in this parameter.   the results obtained lay the ground for the high - precision determination of nuclear magnetic dipole moments from measurements of the @xmath0-factor of hydrogen - like ions.
we report the discovery of a gravitationally lensed quasar resulting from our survey for lenses in the southern sky.   radio images of j16320033  with the vla and atca exhibit two compact, flat - spectrum components with separation @xmath0 and flux density ratio 13.2.   images with the hst reveal the optical counterparts to the radio components and also the lens galaxy.   an optical spectrum of the bright component, obtained with the first magellan telescope, reveals quasar emission lines at redshift 3.42.   deeper radio images with merlin and the vlba reveal a faint third radio component located near the center of the lens galaxy, which is either a third image of the background quasar or faint emission from the lens galaxy.
recently, it has been demonstrated that the chemical composition of jets in heavy ion collisions is significantly altered compared to jets in the vacuum.   this signal can be used to probe the medium formed in nuclear collisions. in this study   we investigate the possibility that fast light quarks and gluons can convert to heavy quarks when passing through a quark gluon plasma.   we study the rate of light to heavy jet conversions in a consistent fokker - planck framework and investigate their impact on the production of high-@xmath0 charm and bottom quarks at rhic and lhc.
we investigate a mechanism of the appearance of kinetic friction in granular materials.   we consider a small number of intervening inelastic particles between two rough surfaces as one of the simplest dynamical models to study granular friction.   the resistance force applied to the upper surface is numerically calculated.   we find that the resistance force @xmath0 is scaled as @xmath1 for a small pulling velocity @xmath2.   the time average @xmath3 in the limit @xmath4 is not zero owing to the mutual collisions between the intervening particles.   the nonzero @xmath5 implies the appearance of kinetic friction in this simple dynamical system.
cosmic - ray background fluxes were modeled based on existing measurements and theories and are presented here.   the model, originally developed for the gamma - ray large area space telescope ( glast ) balloon experiment, covers the entire solid angle ( @xmath0 ), the sensitive energy range of the instrument ( @xmath1 ) and abundant components ( proton, alpha, @xmath2, @xmath3, @xmath4, @xmath5 and gamma ).   it is expressed in analytic functions in which modulations due to the solar activity and the earth geomagnetism are parameterized. although the model is intended to be used primarily for the glast balloon experiment, model functions in low - earth orbit are also presented and can be used for other high energy astrophysical missions.   the model has been validated via comparison with the data of the glast balloon experiment.
we discuss characterization of experimental quantum gates by the error matrix, which is similar to the standard process matrix @xmath0 in the pauli basis, except the desired unitary operation is factored out, by formally placing it either before or after the error process.   the error matrix has only one large element, which is equal to the process fidelity, while other elements are small and indicate imperfections.   the imaginary parts of the elements along the left column and/or top row directly indicate the unitary imperfection and can be used to find the needed correction. we discuss a relatively simple way to calculate the error matrix for a composition of quantum gates.   similarly, it is rather straightforward to find the first - order contribution to the error matrix due to the lindblad - form decoherence.   we also discuss a way to identify and subtract the tomography procedure errors due to imperfect state preparation and measurement. in appendices we consider several simple examples of the process tomography and also discuss an intuitive physical interpretation of the lindblad - form decoherence.
we report the detection of upper main sequence stars and red giant branch stars in the halo of an amorphous galaxy, ngc  3077.   the observations were made using wide field planetary camera  2 on board the hubble space telescope.   the red giant branch luminosity function in i - band shows a sudden discontinuity at @xmath0 mag.   identifying this with the tip of the red giant branch ( trgb ), and adopting the calibration provided by lee, freedman, & madore ( 1993 ) and the foreground extinction of @xmath1 mag, we obtain a distance modulus of @xmath2.   this value agrees well with the distance estimates of four other galaxies in the m81 group.   in addition to the rgb stars, we observe a concentration of upper main sequence stars in the halo of ngc  3077, which coincides partially with a feature known as the `` garland ''.   using padua isochrones, these stars are estimated to be @xmath3150 myrs old. assuming that the nearest encounter between ngc  3077 and m81 occurred 280 myrs ago as predicted by the numerical simulations ( yun 1997 ), the observed upper main sequence stars are likely the results of the star formation triggered by the m81-ngc  3077 tidal interaction.   shoko sakai@xmath4 and barry f. madore@xmath5    running headline : _ ngc 3077 _
we outline a scenario which traces a direct path from freely - floating nebula particles to the first 10 - 100km - sized bodies in the terrestrial planet region, producing planetesimals which have properties matching those of primitive meteorite parent bodies.   we call this _ primary accretion_. the scenario draws on elements of previous work, and introduces a new critical threshold for planetesimal formation.   we presume the nebula to be weakly turbulent, which leads to dense concentrations of aerodynamically size - sorted particles having properties like those observed in chondrites.   the fractional volume of the nebula occupied by these dense zones or clumps obeys a probability distribution as a function of their density, and the densest concentrations have particle mass density 100 times that of the gas.   however, even these densest clumps are prevented by gas pressure from undergoing gravitational instability in the traditional sense ( on a dynamical timescale ). while in this state of arrested development  , they are susceptible to disruption by the ram pressure of the differentially orbiting nebula gas  . however, self - gravity can preserve sufficiently large and dense clumps from ram pressure disruption, allowing their entrained particles to sediment gently but inexorably towards their centers, producing 10 - 100 km  sandpile " planetesimals.   localized radial pressure fluctuations in the nebula, and interactions between differentially moving dense clumps, will also play a role that must be allowed for in future studies.   the scenario is readily extended from meteorite parent bodies to primary accretion throughout the solar system.
infrastructure as a service ( iaas ) systems offer on demand virtual infrastructures so reliably and flexibly that users expect a high service level. therefore,   even with regards to internal iaas behaviour, production clouds only adopt novel ideas that are proven not to hinder established service levels. to analyse their expected behaviour,   new ideas are often evaluated with simulators in production iaas system - like scenarios.   for instance, new research could enable collaboration amongst several layers of schedulers or could consider new optimisation objectives such as energy consumption.   unfortunately, current cloud simulators are hard to employ and they often have performance issues when several layers of schedulers interact in them. to target these issues, a new iaas simulation framework ( called dissect - cf ) was designed.   the new simulator s foundation has the following goals : easy extensibility, support energy evaluation of iaass and to enable fast evaluation of many scheduling and iaas internal behaviour related scenarios. in response to the requirements of such scenarios,   the new simulator introduces concepts such as : a unified model for resource sharing and a new energy metering framework with hierarchical and indirect metering options.   then, the comparison of several simulated situations to real - life iaas behaviour is used to validate the simulator s functionality.   finally, a performance comparison is presented between dissect - cf and some currently available simulators.   cloud computing, infrastructure as a service, energy - awareness, resource management, simulation
we describe the effective heavy meson lagrangian for s- and p - wave heavy - light mesons in terms of a model based on meson - quark interactions, where mesonic transition amplitudes are represented by diagrams with heavy mesons attached to loops containing heavy and light constituent quarks.   the model is relativistic and incorporates the heavy quark symmetries.   the universal form factors of the heavy meson transition amplitudes are calculated together with their slopes and compared to existing data and limits. as further applications of the model, strong and radiative decays of @xmath0 and @xmath1 are considered.   the agreement with data is surprisingly good and shows that the model offers a viable alternative to effective meson lagrangians which require a larger number of input parameters.   /#10=#1 - 00=5pt0 by-00 by00.50to0_/ _
.1 in open heavy flavour production at @xmath0 colliders in deeply inelastic @xmath1 scattering has an interesting feature : the structure function @xmath2 for this process is calculable for @xmath3, and is essentially proportional to the gluon density in the photon for smaller @xmath4 values.   we give estimates for event rates at lep2 and a next linear collider in @xmath5 bins, and present differential distributions in the transverse momentum and rapidity of the heavy quark for the case of charm.   we include all next - to - leading - order qcd corrections, and find theoretical uncertainties are well under control.    0.0 in 0.0 in 6.in 9.in -2.9 cm.70 in 1.12ex  = 11
this paper describes the techniques and physical parameters used to produce stable centimetric water drops in microgravity, and to study single cavitation bubbles inside such drops ( parabolic flight campaigns, european space agency esa ).   while the main scientific results have been presented in a previous paper, we shall herein provide the necessary technical background, with potential applications to other experiments.   first, we present an original method to produce and capture large stable drops in microgravity.   this technique succeeded in generating quasi - spherical water drops with volumes up to 8 ml, despite the residual g - jitter.   we find that the equilibrium of the drops is essentially dictated by the ratio between the drop volume and the contact surface used to capture the drop, and formulate a simple stability criterion. in a second part  , we present a setup for creating and studying single cavitation bubbles inside those drops.   in addition, we analyze the influence of the bubble size and position on the drop behaviour after collapse, i.e. jets and surface perturbations.
modified - electroconvulsive therapy ( m - ect ) is administered for the treatment of various psychiatric disorders.   the seizure generalization hypothesis holds that propagation of the induced seizure throughout the whole brain is essential for the effective ect intervention.   however, we encounter many clinical cases where, due to high thresholds, seizure is not induced by the maximum dose of electrical charge.   some studies have indicated that the ultrabrief pulse method, in which pulse width is less than 0.5millisecond ( ms ), is more effective at inducing seizure than conventional brief pulse ( 0.5ms-2.0ms ).   contrary to the studies, we experienced a case of schizophrenia in which m - ect with 1.0 and 1.5 ms width pulse ( referred to as ` long'brief pulse as 0.5ms width pulse is the default in japan ) succeeded in inducing seizure, whereas ultrabrief pulse failed to induce seizure. this case is described in detail.   moreover, we discuss the underlying mechanism of this phenomenon.
we present new traversable wormhole and non - singular black hole solutions in pure, scale - free @xmath0 gravity.   these exotic solutions require no null energy condition violating or   exotic " matter and are supported only by the vacuum of the theory.   it is well known that @xmath1 theories of gravity may be recast as dual theories in the einstein frame.   the solutions we present are found when the conformal transformation required to move to the dual frame is singular. for quadratic @xmath0 gravity, the required conformal factor is identically zero for spacetimes with @xmath2.   solutions in this case are argued to arise in the strong coupling limit of general relativity.
observations of the hi 21 cm transition line promises to be an important probe into the cosmic dark ages and epoch of reionization.   one of the challenges for the detection of this signal is the accuracy of the foreground source removal.   this paper investigates the extragalactic point source contamination and how accurately the bright sources ( @xmath0  jy ) should be removed in order to reach the desired rms noise and be able to detect the 21 cm transition line. here,   we consider position and flux errors in the global sky - model for these bright sources as well as the frequency independent residual calibration errors.   the synthesized beam is the only frequency dependent term included here.   this work determines the level of accuracy for the calibration and source removal schemes and puts forward constraints for the design of the cosmic reionization data reduction scheme for the upcoming low frequency arrays like mwa, paper, etc.   we show that in order to detect the reionization signal the bright sources need to be removed from the data - sets with a positional accuracy of @xmath1  arc - second.   our results also demonstrate that the efficient foreground source removal strategies can only tolerate a frequency independent antenna based mean residual calibration error of @xmath2 in amplitude or @xmath3  degree in phase, if they are constant over each days of observations ( 6 hours ). in future papers   we will extend this analysis to the power spectral domain and also include the frequency dependent calibration errors and direction dependent errors ( ionosphere, primary beam, etc ).
we discuss the mechanism of anomalous hall effect related to the contribution of electron states below the fermi surface ( induced by the berry phase in momentum space ).   our main calculations are made within a model of two - dimensional electron gas with spin - orbit interaction of the rashba type, taking into account the scattering from impurities.   we demonstrate that such an `` intrinsic '' mechanism can dominate but there is a competition with the impurity - scattering mechanism, related to the contribution of states in the vicinity of fermi surface.   we also show that the contribution to the hall conductivity from electron states close to the fermi surface has the intrinsic properties as well. 0.5 cm
we discuss chiral and deconfinement aspects of the finite temperature transition in qcd using improved staggered actions.   we study different quantities related to chiral and deconfinement transition and discuss their cutoff dependence.   contrary to some earlier lattice results we find that the chiral and deconfinement transition are not closely interconnected.
signal processing in biological systems is delicately executed by specialised networks, which are modular assemblies of network motifs.   the motifs are independently functional circuits found in enormous numbers in any living cell.   a very common network motif is the feed - forward loop ( ffl ), which regulates a downstream node by an upstream one in a direct and an indirect way within the network.   if the direct and indirect regulations go antagonistic, the motif is known as an incoherent ffl ( icffl ).   the current study is aimed at exploring the reason for the variation in the evolutionary selection of the four types of icffls. as comparative measures,   i compute sensitivity amplification, adaptation precision and efficiency from the temporal dynamics and mutual information between the input - output nodes of the motifs at steady state.   the icffl ii performs very efficiently in adaptation but poor in information processing. on the other hand, icffl i and iii are better in information transmission compared to adaptation efficiency. which is the fittest among them under the pressure of natural selection?   to sort out this puzzle, i take help from the multi - objective pareto efficiency.   the results, found in the pareto task space, are in good agreement with the reported abundance level of all the types in eukaryotes as well as prokaryotes.
recent high - resolution observations of metal absorption lines in high - redshift damped ly@xmath0  systems have shown that, a tracer of moderately - ionized gas, very often has a velocity structure indistinguishable from that of low - ionization gas.   regions of ionized and neutral hydrogen in these systems are likely cospatial.   the higher - ionization and absorption shows a much weaker or non - existent correlation with the low ionization material, implying that the regions traced by are photoionized by a soft ( stellar ) spectrum, by a hard ( power law ) spectrum with a very low ionization parameter, or a combination of both.   we discuss the ionization of the damped ly@xmath0  systems and use photoionization equilibrium models to make quantitative estimates of its effects on abundance studies in these systems.   we show that ionization effects may be large enough to account for the observed dispersion in absolute metal abundances in damped ly@xmath0  systems, causing systematically higher abundances in lower column density systems.   the observed si@xmath1/fe@xmath1 and zn@xmath1/cr@xmath1 ratios may systematically overestimate the intrinsic si / fe and zn / cr ratios, respectively, if ionized gas is present in these systems, thereby mimicking the effects of @xmath0-element enrichment or dust depletion.    to appear in _ the astrophysical journal letters. _
current explanation of the overabundance of dark matter subhalos in the local group ( lg ) indicates that there maybe a limit on mass of a halo, which can host a galaxy.   this idea can be tested using voids in the distribution of galaxies : at some level small voids should not contain any ( even dwarf ) galaxies.   we use observational samples complete to @xmath0 with distances less than 8mpc to construct the void function ( vf ) : the distribution of sizes of voids empty of any galaxies.   there are @xmath1 voids with sizes ranging from 1 to 5mpc.   we also study the distribution of dark matter halos in very high resolution simulations of the lcdm model.   the theoretical vf matches the observations remarkably well only if we use halos with circular velocities larger than @xmath2km / s.   this agrees with the local group predictions.   small voids look quite similar to their giant cousins : the density has a minimum at the center of a void and it increases as we get closer to the border.   thus, both the local group data and the nearby voids indicate that isolated halos below @xmath2km / s must not host galaxies and that small ( few mpc ) voids are truly dark.
xassist is a nasa aisr - funded project for the automation of x - ray astrophysics, with emphasis on galaxies.   it is nearing completion of its initially funded effort, and is working well for _ chandra _ and _ rosat _ data.   initial support for _ xmm - newton _ data is present as well.   it is capable of data reprocessing, source detection, and preliminary spatial, temporal and spectral analysis for each source with sufficient counts.   the bulk of the system is written in python, which in turn drives underlying software ( ciao for _ chandra _ data, etc. ).   future work will include a gui ( mainly for beginners and status monitoring ) and the exposure of at least some functionality as web services.   the latter will help xassist to eventually become part of the vo, making advanced queries possible, such as determining the x - ray fluxes of counterparts to hst or sdss sources ( including the use of unpublished x - ray data ), and add the ability of `` on - the - fly '' x - ray processing.   pipelines are running on _ rosat _, _ chandra _ and now _ xmm - newton _ observations of galaxies to demonstrate xassist s capabilities, and the results are available online ( in real time ) at.   xassist itself as well as various associated projects are available for download.
we present results of an analytic and numerical calculation that studies the relationship between the time of initial foot contact and the ground reaction force of human gait and explores the dynamic principle of center of mass. assuming the ground reaction force of both feet to be the same in the same phase of a stride cycle  , we establish the relationships between the time of initial foot contact and the ground reaction force, acceleration, velocity, displacement and average kinetic energy of center of mass.   we employ the dispersion to analyze the effect of the time of the initial foot contact that imposes upon these physical quantities.   our study reveals that when the time of one foot s initial contact falls right in the middle of the other foot s stride cycle, these physical quantities reach extrema. an action function has been identified as the dispersion of the physical quantities and optimized analysis used to prove the least - action principle in gait.   in addition to being very significant to the research domains such as clinical diagnosis, biped robot s gait control, the exploration of this principle can simplify our understanding of the basic properties of gait.
asphaltene and smaller aromatic molecules tend to form linear nanoaggregates in bitumen. over   the years bitumen undergoes chemical aging and during this process, the size of the nanoaggregate increases.   this increase is associated with an increase in viscosity and brittleness of the bitumen, eventually leading to road deterioration.   this paper focuses on understanding the mechanisms behind nanoaggregate size and stability.   we used molecular dynamics simulations to quantify the probability of having a nanoaggregate of a given size in the stationary regime. to model this complicated behavior, we chose first to consider the simple case where only asphaltene molecules are counted in a nanoaggregate.   we used a master equation approach and a related statistical mechanics model.   the linear asphaltene nanoaggregates behave as a rigid linear chain.   the most complicated case where all aromatic molecules are counted in a nanoaggregate is then discussed.   the linear aggregates where all aromatic molecules are counted seem to behave as a flexible linear chain.    corresponding author : c. a. lemarchand, e - mail : clairel@ruc.dk
high - energy gamma - ray emission is theoretically expected to arise in tight binary star systems ( with high mass loss and high velocity winds ), although the evidence of this relationship has proven to be elusive so far. here   we present the first bounds on this putative emission from isolated wolf - rayet ( wr ) star binaries, wr147 and wr146, obtained from observations with the magic telescope.   very high energy gamma rays ; wolf - rayet binary systems ; magic
we study the relaxation dynamics of a _ nonequilibrium _ luttinger liquid after a sudden interaction switch - on ( `` quench '' ), focussing on a double - step initial momentum distribution function. in the framework of the non - equilibrium bosonization,   the results are obtained in terms of singular fredholm determinants that are evaluated numerically and whose asymptotics are found analytically. while the quasi - particle weights decay exponentially with time after the quench,   this is not a relaxation into a thermal state, in view of the integrability of the model.   the steady - state distribution emerging at infinite times retains two edges which support luttinger - liquid - like power - law singularities smeared by dephasing.   the obtained critical exponents and the dephasing length are found to depend on the initial nonequilibrium state.
hartree - fock theory predicted stripe or bubble phase in the third and higher landau levels for two - dimensional electrons, and experimental evidences has been accumulated. in this paper theoretical confirmation of the stripe phase and bubble phase in higher landau level   is given by means of the density matrix renormalization group ( dmrg ) method, which can give essentially exact ground state for electron systems with up to 18 electrons. from the study of the pair correlation function,   the stripe phase, bubble phase, and the wigner crystal phase are identified, and phase diagram is obtained.   the reentrant integer quantum hall state is identified as the bubble state.   the phase diagram of the fourth landau level shows more diversity than the third level.   # 1@xmath0#1 # 1#2#3#4#1 * # 2 * ( # 4 ) # 3    2
the nebular spectra of the broad - lined, sn1998bw - like type ic sn2002ap are studied by means of synthetic spectra.   two different modelling techniques are employed. in one technique,   the sn ejecta are treated as a single zone, while in the other a density and abundance distribution in velocity is used from an explosion model. in both cases, heating caused by @xmath0-ray and positron deposition   is computed ( in the latter case using a monte carlo technique to describe the propagation of @xmath0-rays and positrons ), as is cooling via forbidden - line emission.   the results are compared, and although general agreement is found, the stratified models are shown to reproduce the observed line profiles much more accurately than the single - zone model.   the explosion produced @xmath1 of @xmath2ni.   the distribution in velocity of the various elements is in agreement with that obtained from the early - time models, which indicated an ejected mass of @xmath3 with a kinetic energy of @xmath4erg.   nebular spectroscopy confirms that most of the ejected mass ( @xmath5 ) was oxygen.   the presence of an oxygen - rich inner core, combined with that of @xmath2ni  at high velocities as deduced from early - time models, suggests that the explosion was asymmetric, especially in the inner part.
we analyze in detail an open cavity array using mean - field description, where each cavity field is coupled to a number of three - level atoms.   such system is highly tunable and can be described by a jaynes - cummings like hamiltonian with additional non - linear terms. in the single cavity case   we provide simple analytic solutions and show, that the system features a bistable region.   the extra non - linear term gives rise to a rich dynamical behaviour including occurrence of limit cycles through hopf bifurcations. in the limit of large non - linearity,   the system exhibits an ising like phase transition as the coupling between light and matter is varied.   we then discuss how these results extend to the two - dimensional case.
in this paper, we discuss a supervisory control problem of modular discrete - event systems that allows for a distributed computation of supervisors. we provide a characterization and an algorithm to compute the supervisors. if the specification does not satisfy the properties, we make use of a relaxation of coordination control to compute a sublanguage of the specification for which the supervisors can be computed in a distributed way.
we report on the detection of main sequence stars belonging to the recently identified canis major galaxy in a field located at @xmath0 from the center of the stellar system. with main sequence fitting   we obtain a distance modulus @xmath1 to the dwarf, corresponding to a distance of @xmath2 kpc, in full agreement with previous estimates based on the photometric parallax of m - giants. from the comparison with theoretical isochrones   we constrain the age of the main population of the canis major system in the range @xmath3 gyr. a blue plume of likely younger stars ( age @xmath4 gyr ) is also identified.   the available colour magnitude diagrams of open clusters that may be projected onto the main body of canis major are also briefly analyzed.   the position, distance and stellar population of the old open clusters am-2 and tombaugh  2 strongly suggest that they are physically associated with the canis major galaxy. using our own photometry and data from 2mass and the gsc2.2 surveys we demonstrate that the claim by momany et al. that the cma overdensity is entirely due to the galactic warp is not supported by the existing observations,   once all the available pieces of information are taken into account.   it is shown that the cma overdensity clearly emerges at a heliocentric distance of @xmath5 kpc above any overdensity possibly produced by the galactic warp.       galaxy : structure - galaxies : dwarf - open clusters : general - open clusters : individual : ngc  2477, tombaugh  1, tombaugh  2, am-2, berkeley  33
this paper studies an optimal control problem for continuous - time stochastic systems subject to reachability objectives specified in a subclass of metric interval temporal logic specifications, a temporal logic with real - time constraints.   we propose a probabilistic method for synthesizing an optimal control policy that maximizes the probability of satisfying a specification based on a discrete approximation of the underlying stochastic system.   first, we show that the original problem can be formulated as a stochastic optimal control problem in a state space augmented with finite memory and states of some clock variables.   second, we present a numerical method for computing an optimal policy with which the given specification is satisfied with the maximal probability in point - based semantics in the discrete approximation of the underlying system.   we show that the policy obtained in the discrete approximation converges to the optimal one for satisfying the specification in the continuous or dense - time semantics as the discretization becomes finer in both state and time.   finally, we illustrate our approach with a robotic motion planning example.
we develop a systematic analytic approach to aging effects in quantum disordered systems in contact with an environment. within the closed - time path - integral formalism we include dissipation by coupling the system to a set of independent harmonic oscillators that mimic a quantum thermal bath. after integrating over the bath variables and averaging over disorder we obtain an effective action that determines the real - time dynamics of the system.   the classical limit yields the martin - siggia - rose generating functional associated to a colored noise.   we apply this general formalism to a prototype model related to the @xmath0 spin - glass.   we show that the model has a dynamic phase transition separating the paramagnetic from the spin - glass phase and that quantum fluctuations depress the transition temperature until a quantum critical point is reached.   we show that the dynamics in the paramagnetic phase is stationary but presents an interesting crossover from a region controlled by the classical critical point to another one controlled by the quantum critical point.   the most characteristic property of the dynamics in a glassy phase, namely aging, survives the quantum fluctuations. in the sub - critical region   the quantum fluctuation - dissipation theorem is modified in a way that is consistent with the notion of effective temperatures introduced for the classical case.   we discuss these results in connection with recent experiments in dipolar quantum spin - glasses and the relevance of the effective temperatures with respect to the understanding of the low temperature dynamics.   = 10000
we show that the intermediate scattering function @xmath0 for neutron scattering ( ns ) can be expanded naturely with respect to a set of molecular correlation functions that give a complete description of the translational and orientational two  point correlations in the liquid.   the general properties of this expansion are discussed with special focus on the @xmath1dependence and hints for a ( partial ) determination of the molecular correlation functions from neutron scattering results are given.   the resulting representation of the static structure factor @xmath2 is studied in detail for a model system using data from a molecular dynamics simulation of a supercooled liquid of rigid diatomic molecules.   the comparison between the exact result for @xmath2 and different approximations that result from a truncation of the series representation demonstrates its good convergence for the given model system. on the other hand   it shows explicitly that the coupling between translational ( tdof ) and orientational degrees of freedom ( odof ) of each molecule and rotational motion of different molecules can not be neglected in the supercooled regime.   further we report the existence of a prepeak in the ns   static structure factor of the examined fragile glassformer, demonstrating that prepeaks can occur even in the most simple molecular liquids. besides examining the dependence of the prepeak on the scattering length and the temperature we use the expansion of @xmath2 into molecular correlation functions to point out intermediate range orientational order as its principle origin.    2
the euclidean quantum amplitude to go between data specified on an initial and a final hypersurface may be approximated by the tree amplitude @xmath0 where @xmath1 is the euclidean action of the classical solution joining the initial and final data. in certain cases   the tree amplitude is exact.   we study @xmath1, and hence the quantum amplitude, in the case of a spherically symmetric riemannian gravitational field coupled to a spherically symmetric scalar field.   the classical scalar field obeys an elliptic equation, which we solve using relaxation techniques, in conjunction with the field equations giving the gravitational field.   an example of the transition from linearity to non - linearity is presented and power law behavior of the action is demonstrated.   pacs numbers 04.20.-q, 04.20.jb, 04.60.+n    -18pt
the effects of electron - electron interaction of a two - electron nanoring on the energy levels and far - infrared spectroscopy have been investigated based on a model calculation which is performed within the exactly numerical diagonalization.   it is found that the interaction changes the energy spectra dramatically, and also shows significant influence on the far - infrared spectroscopy.   the crossings between the lowest spin - singlet and triplet states induced by the coulomb interaction are clearly revealed.   our results are related to the experiment recently carried out by a. lorke _   et al. _   [ phys.   rev.   lett.   84, 2223 ( 2000 ) ].   * pacs number(s ) * : 71.15.-m, 73.61.-r, 78.30.-j, 73.20.dx
can large distance high energy qcd be described by reggeon field theory as an effective emergent theory? we start to investigate the issue employing functional renormalisation group techniques.   address = ii.   institut fr theoretische physik, universitt hamburg, luruper chaussee 149, d-22761 hamburg, germany     address = dep  . de fisica, uni.   tecnica federico santa maria, aveda.espana 1680, casilla 110-v, valparaiso, chile     address = infn sezione di bologna, via irnerio 46, i-40126 bologna, italy
we express modular and weak values of three- and high - level quantum systems in their polar form. within the majorana representation and a purely geometric approach, we point out that this complex values of @xmath0-level quantum systems possess a modulus determined by the product of @xmath1 square roots of probability ratios and an argument deduced from a sum of @xmath1 spherical polygons on the bloch sphere.   this theoretical results demonstrate that the discontinuous effects around singularities of weak values have a purely geometric origin with no classical counterpart.   furthermore, the geometric approach is used to extend the three - box paradox @xcite to a larger class of quantum phenomena : quantum entanglement.   therefore, we present a two spin-@xmath2 measurement experiment, for which alice and bob come to counter - intuitive conclusions about the particles state between pre- and postselection.
the time evolution of initially balanced, rapidly rotating models for an isolated disk of highly flattened galaxies of stars is calculated.   the method of direct integration of the newtonian equations of motion of stars over a time span of many galactic rotations is applied.   use of modern concurrent supercomputers has enabled us to make long simulation runs using a sufficiently large number of particles @xmath0.   one of the goals of the present simulation is to test the validities of a modified local criterion for stability of jeans - type gravity perturbations ( e.g. those produced by a barlike structure, a spontaneous perturbation and/or a companion galaxy ) in a self - gravitating, infinitesimally thin and collisionless disk.   in addition to the local criterion we are interested in how model particles diffuse in velocity.   this is of considerable interest in the kinetic theory of stellar disks.   certain astronomical implications of the simulations to actual disk - shaped ( i.e. rapidly rotating ) galaxies are explored.   the weakly nonlinear, or quasi - linear kinetic theory of the jeans instability in disk galaxies of stars is described as well.   kluwer  academic  publishers prepress department, + p.o.   box  17, 3300  aa  dordrecht, the  netherlands + e - mail : texhelp@wkap.nl + fax : + 31 78 6392500
molecular dynamics simulations of spc / e water confined in a silica pore are presented.   the simulations have been performed at different hydration levels and temperatures to study the single - particle dynamics. due to the confinement and to the presence of a hydrophilic surface  , the dynamic behaviour of the liquid appears to be strongly dependent on the hydration level.   on lowering temperature and/or hydration level the intermediate scattering function displays a double - step relaxation behaviour whose long time tail is strongly non - exponential. at higher hydrations two quite distinct subsets of water molecules are detectable.   those belonging to the first two layers close to the substrate suffer a severe slowing down already at ambient temperature. while the behaviour of the remaining ones is more resemblant to that of supercooled bulk spc / e water. at lower hydrations and/or temperatures the onset of a slow dynamics due to the cage effect and a scenario typical of supercooled liquids approaching the kinetic glass transition   is observed.   moreover, for low hydrations and/or temperatures, the intermediate scattering function clearly displays an overshoot, which can be assigned to the so called `` boson peak ''.    2
it has been known for some time that the milky way is a barred disk galaxy.   more recently several studies inferred from starcount observations that the galaxy must contain a separate, new, flat _ long bar _ component, twisted relative to the barred bulge. here   we use a simulation with a _ boxy bulge and bar _ to suggest that these observations can be reproduced with a single structure. in this simulation   a stellar bar evolved from the disk, and the boxy bulge originated from it through secular evolution and the buckling instability.   we calculate starcount distributions for this model at different longitudes and latitudes, in a similar way as observers have done for resolved starcounts.   good agreement between the simulation and the observations can be achieved for a suitable snapshot, even though the simulation has a single _ boxy bulge and bar _ structure. in this model,   part of the _ long bar _   signature is due to a volume effect in the starcounts, and another part is due to chosing a snapshot in which the planar part of the _ boxy bulge and bar _ has developed leading ends through interaction with the adjacent spiral arm heads.   we also provide predictions from this model for the line - of - sight velocity distributions at the longitudes with the _ long bar _   signature, for comparison with upcoming surveys.
deep j and ks band images covering a @xmath0 arcmin area centered on the ntt deep field have been obtained during the science verification of sofi at the ntt.   these images were made available via the web in early june.   the preliminary results we have obtained by the analysis of these data are the following : _   i ) _ the counts continue to rise with no evidence of a turnover or of a flattening down to the limits of the survey ( ks=22.5 and j=24 ) ; _ ii ) _ we find a slope @xmath10.37 in agreement with most of the faintest surveys but much steeper than the hawaii survey ; _ iii ) _   fainter than ks@xmath2 and j@xmath3, the median j - k color of galaxies shows a break in its reddening trend turning toward bluer colors ; _ iv ) _ faint bluer galaxies also display a larger compactness index, and a smaller apparent size.   paolo saracco + osservatorio astronomico di brera + via e. bianchi 46, 22055 merate, italy + e - mail : saracco@merate.mi.astro.it
let @xmath0 be a 3-uniform hypergraph with @xmath1 vertices. a tight hamilton cycle @xmath2 is a collection of @xmath1 edges for which there is an ordering of the vertices @xmath3 such that every triple of consecutive vertices @xmath4 is an edge of @xmath5 ( indices are considered modulo @xmath1 ).   we develop new techniques which enable us to prove that under certain natural pseudo - random conditions, almost all edges of @xmath0 can be covered by edge - disjoint tight hamilton cycles, for @xmath1 divisible by 4.   consequently, we derive the corollary that random 3-uniform hypergraphs can be almost completely packed with tight hamilton cycles * whp *, for @xmath1 divisible by 4 and @xmath6 not too small. along the way, we develop a similar result for packing hamilton cycles in pseudo - random digraphs with even numbers of vertices.
we explore the device potential of tunable - gap bilayer graphene fet exploiting the possibility of opening a bandgap in bilayer graphene by applying a vertical electric field via independent gate operation.   we evaluate device behavior using atomistic simulations based on the self - consistent solution of the poisson and schrdinger equations within the negf formalism.   we show that the concept works, but bandgap opening is not strong enough to suppress band - to - band tunneling in order to obtain a sufficiently large @xmath0 ratio for cmos device operation.   * keyworks : * negf, graphene, bilayer, tight - binding hamiltonian, poisson / schrdinger.
we present results from stacking analyses, using the 1  ms  deep field north data, that constrain the x - ray emission of lyman break galaxies at @xmath0  24. stacking the counts from 24 individually undetected lyman break galaxies located within the hubble deep field north, we have obtained average detections of these objects in the resulting 0.58.0  kev and 0.52.0  kev images   ; these images have effective exposure times of 22.4  ms ( 260 days ).   monte carlo testing empirically shows the detections to be highly significant.   the average rest - frame 28  kev luminosity of a lyman break galaxy is derived to be @xmath1  erg  s@xmath2, comparable to that of the most x - ray luminous starbursts in the local universe  . the observed ratio of x - ray to @xmath3-band luminosity is somewhat, but not greatly, higher than that seen from local starbursts.   the x - ray emission probably arises from a combination of high - mass x - ray binaries, `` super - eddington '' x - ray sources, and low - luminosity active galactic nuclei.
we report the discovery of wts-1b, the first extrasolar planet found by the wfcam transit survey, which began observations at the 3.8-m united kingdom infrared telescope ( ukirt ) in august 2007.   light curves comprising almost 1200 epochs with a photometric precision of better than 1 per cent to @xmath0 were constructed for @xmath1 stars and searched for periodic transit signals. for one of the most promising transiting candidates, high - resolution spectra taken at the hobby - eberly telescope ( het ) allowed us to estimate the spectroscopic parameters of the host star, a late - f main sequence dwarf ( v=16.13 ) with possibly slightly subsolar metallicity, and to measure its radial velocity variations.   the combined analysis of the light curves and spectroscopic data resulted in an orbital period of the substellar companion of 3.35 days, a planetary mass of 4.01@xmath20.35@xmath3, and a planetary radius of @xmath4  @xmath5.   wts-1b has one of the largest radius anomalies among the known hot jupiters in the mass range 3 - 5@xmath3. the high irradiation from the host star ranks the planet in the pm class  .        extrasolar planet, hot - jupiter, radius anomaly, errata corrige
we use a new method to trace backwards the star formation history of the milky way disk, using a sample of m dwarfs in the solar neighbourhood which is representative for the entire solar circle.   m stars are used because they show h@xmath0 emission until a particular age which is a well calibrated function of their absolute magnitudes.   this allows us to reconstruct the rate at which disk stars have been born over about half the disk s lifetime.   our star formation rate agrees well with those obtained by using other, independent, methods and seems to rule out a constant star formation rate.   the principal result of this study is to show that a relation of the schmidt - kennicut type ( which relates the star formation rate to the interstellar gas content of galaxy disks ) has pertained in the milky way disk during the last 5 gyr.   the star formation rate we derive from the m dwarfs and the interstellar gas content of the disk can be inferred as a function of time from a model of the chemical enrichment of the disk, which is well constrained by the observations indicating that the metallicity of the galactic disk has remained nearly constant over the timescales involved.   we demonstrate that the star formation rate and gas surface densities over the last 5 gyrs can be accurately described by a schmidt - kennicutt law with an index of @xmath1 = 1.45@xmath2.   this is, within statistical uncertainties, the same value found for other galaxies.
the ground state properties of a paramagnetic mott insulator are investigated in the presence of an external electrical field using the inhomogeneous gutzwiller approximation for a single band hubbard model in a slab geometry.   the metal insulator transition is shifted towards higher hubbard repulsions by applying an electric field perpendicular to the slab.   the spatial distribution of site dependent quasiparticle weight shows that the quasiparticle weight is maximum in few layers beneath the surface.   moreover only at higher hubbard repulsion, larger than the bulk critical u, the electric field will be totally screened only for centeral cites.   our results show that by presence of an electric field perpendicular to a thin film made of a strongly correlated material, states near the surface will remain metallic while the bulk becomes insulating after some critical u. in contrast, in the absence of the electric field the surface becomes insulating before the bulk.
we have constructed models for the sun at three stages of its evolution : a zero - age main sequence model, the present sun, and a subgiant model. for each model,   the turbulent pressure and turbulent kinetic energy were calculated from 3-d radiative hydrodynamical simulations ( described in the poster by robinson et al. ), and inserted into the 1-d stellar models.   we note that in these simulations, the turbulent pressure is not a free parameter, but can be computed from the resulting velocity field.   we show the calculated p - mode frequencies for the model of the present sun, with and without turbulent pressure, and compare them to the observed solar frequencies.   when the turbulent pressure is included in the models, the calculated frequencies are brought closer to the observed frequencies in the sun by up to two @xmath0, strictly from structural effects.   the effect of including turbulent pressure on p - mode frequencies is also shown for the zero - age main sequence model.   our models also suggest that the importance of turbulent pressure increases as the star evolves into the subgiant region.   we discuss the importance of also including realistic turbulence as well as radiation in the non - adiabatic calculation of oscillation frequencies.
we have performed first - principles calculations of si / sio@xmath0 superlattices in order to examine their electronic states, confinement and optical transitions, using linearized - augmented - plane - wave techniques and density - functional theory.   two atomic models having fairly simple interface structure are considered ; they differ in the way dangling bonds at interfaces are satisfied.   we compare our first - principles band structures with those from tight - binding calculations.   the real and imaginary parts of the dielectric function are calculated at the fermi - golden - rule level and used to estimate the absorption coefficients.   confinement is confirmed by the dispersionless character of the electronic band structures in the growth direction.   optical enhancement is shown to exist by comparing the direct and indirect transitions in the band structures with the related transitions in bulk - si.   the role played by the interface on the optical properties is assessed by comparing the absorption coefficients from the two models.
we give new proofs of soundness ( all representable functions on base types lies in certain complexity classes ) for elementary affine logic, lfpl  ( a language for polytime computation close to realistic functional programming introduced by one of us ), light affine logic and soft affine logic.   the proofs are based on a common semantical framework which is merely instantiated in four different ways.   the framework consists of an innovative modification of realizability which allows us to use resource - bounded computations as realisers as opposed to including all turing computable functions as is usually the case in realizability constructions.   for example, all realisers in the model for lfpl  are polynomially bounded computations whence soundness holds by construction of the model.   the work then lies in being able to interpret all the required constructs in the model. while being the first entirely semantical proof of polytime soundness for light logics, our proof also provides a notable simplification of the original already semantical proof of polytime soundness for lfpl.   a new result made possible by the semantic framework is the addition of polymorphism and a modality to lfpl  thus allowing for an internal definition of inductive datatypes.
in the na63 collaboration we have addressed the question of the potential inadequacy of the commonly used migdal formulation of the landau - pomeranchuk - migdal ( lpm ) effect by measuring the photon emission by and electrons in the range 100 mev - 4 gev, in targets of lowdensitypolyethylene ( ldpe ), c, al, ti, fe, cu, mo and, as a reference target, ta. for each target and energy, a comparison between simulated values based on the lpm suppression of incoherent bremsstrahlung is shown, taking multi - photon effects into account.   for these targets and energies, we find that migdal s theoretical formulation is adequate to a precision of better than about 5%, irrespective of the target substance.
the @xmath0 ( 2000  ) luminosity function ( hereafter @xmath0 lf ) of coma cluster galaxies, based on more than 120 members, is computed as the statistical difference between counts in the coma direction and in the field.   our @xmath0 lf is an up - date of a preliminary constrain on the @xmath0 lf previously computed without the essential background counts.   the @xmath0 lf is well described by a power law with slope @xmath1, or equivalently, by a schechter function with @xmath2 much brighter than the brightest cluster galaxy and with a slope @xmath3 or larger. in spite of what happens in the optical band,   low luminosity galaxies give a large contribution to the integral luminosity, and by inference, to the total metal production rate.   galaxies blue in @xmath4 and/or @xmath5 dominate the coma cluster @xmath0 lf, both in number and luminosity.   the major source of error in the estimate of the @xmath0 lf cames from the background determination in the coma direction, which is still uncertain, even though constrained at high and low amplitudes by redshift surveys covering the studied field.
we present results of direct imaging observations for hat - p-7 taken with the subaru hiciao and the calar alto astralux. since the close - in transiting planet hat - p-7b   was reported to have a highly tilted orbit, massive bodies such as giant planets, brown dwarfs, or a binary star are expected to exist in the outer region of this system.   we show that there are indeed two candidates for distant faint stellar companions around hat - p-7.   we discuss possible roles played by such companions on the orbital evolution of hat - p-7b.   we conclude that as there is a third body in the system as reported by winn et al.   ( 2009, apjl, 763, l99 ), the kozai migration is less likely while planet - planet scattering is possible.
elastic models of the glass transition relate the relaxation dynamics and the elastic properties of structural glasses.   they are based on the assumption that the relaxation dynamics occurs through activated events in the energy landscape whose energy scale is set by the elasticity of the material.   here we investigate whether such elastic models describe the relaxation dynamics of systems of particles interacting via a purely repulsive harmonic potential, focusing on a volume fraction and temperature range that is characterized by entropy   driven water  like density anomalies.   we do find clear correlations between relaxation time and diffusivity on the one hand, and plateau shear modulus and debye  waller factor on the other, thus supporting the validity of elastic models of the glass transition.   however, we also show that the plateau shear modulus is not related to the features of the underlying energy landscape of the system, at variance with recent results for power  law potentials.   this challenges the common potential energy landscape interpretation of elastic models.    structural glass, elastic models, deby  waller factor
we discuss the quark condensate of the vacuum inside the baryon.   we analyze the 1 + 1 dimensional chiral bag in analogy with the realistic 1 + 3 dimensional one.   the nambu  jona - lasinio ( njl ) type interaction is used to investigate the quark condensate in the chiral bag. considering the strong meson - quark coupling, we solve the mean field solution to the scalar and pseudoscalar channels. extracting the finite values of the chiral casimir energy and the quark condensate by proper regularization,   the resulting self - consistent equation allows a generation of a finite dynamical quark mass inside the bag.
we study the virial mass discrepancy in the context of a dpg brane - world scenario and show that such a framework can offer viable explanations to account for the mass discrepancy problem.   this is done by defining a geometrical mass @xmath0 that we prove to be proportional to the virial mass. estimating @xmath0 using observational data, we show that it behaves linearly with @xmath1 and has a value of the order of @xmath2, pointing to a possible resolution of the virial mass discrepancy.   we also obtain the radial velocity dispersion of galaxy clusters and show that it is compatible with the radial velocity dispersion profile of such clusters.   this velocity dispersion profile can be used to differentiate various models predicting the virial mass.
we consider a bandit problem over a graph where the rewards are not directly observed. instead  , the decision maker can compare two nodes and receive ( stochastic ) information pertaining to the difference in their value.   the graph structure describes the set of possible comparisons. consequently, comparing between two nodes that are relatively far requires estimating the difference between every pair of nodes on the path between them.   we analyze this problem from the perspective of sample complexity : how many queries are needed to find an approximately optimal node with probability more than @xmath0 in the pac setup?   we show that the topology of the graph plays a crucial in defining the sample complexity : graphs with a low diameter have a much better sample complexity.
we present a population analysis of the nuclear stellar cluster of the milky way based on adaptive optics narrow band spectral energy distributions.   we find strong evidence for the lack of a stellar cusp and a similarity of the late type luminosity function to the bulge klf.
the idea that grbs originate from uniform jets has been used to explain numerous observations of breaks in the grb afterglow lightcurves.   we explore the possibility that grbs instead originate from a structured jet that may be quasi - universal, where the variation in the observed properties of grbs is due to the variation in the observer viewing angle.   we test how various models reproduce the jet data of bloom, frail, & kulkarni ( 2003 ), which show a negative correlation between the isotropic energy output and the inferred jet opening angle ( in a uniform jet configuration ).   we find, consistent with previous studies, that a power - law structure for the jet energy as a function of angle gives a good description.   however, a gaussian jet structure can also reproduce the data well, particularly if the parameters of the gaussian are allowed some scatter.   we place limits on the scatter of the parameters in both the gaussian and power - law models needed to reproduce the data, and discuss how future observations will better distinguish between these models for the grb jet structure.   in particular, the gaussian model predicts a turnover at small opening angles and in some cases a sharp cutoff at large angles, the former of which may already have been observed.   we also discuss the predictions each model makes for the observed luminosity function of grbs and compare these predictions with the existing data.
modern gas detectors for detection of particles require f - based gases for optimal performance.   recent regulations demand the use of environmentally unfriendly f - based gases to be limited or banned.   this review studies properties of potential eco - friendly gas candidate replacements.   0.5 cm keywords : gas detectors, muon detectors, gem, rpc, gwp, odp, eco - friendly gas, quantum chemistry, nwchem, rt - tddft, absorption spectrum, ionization energy    _ submitted to journal of instrumentation _    0.5 cm    0.5 cm    l l + @xmath0 & + @xmath1 & + @xmath2 & + @xmath3 & +    2
we present an x - ray absorption model for the interstellar medium, to be referred to as ismabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available. using high - resolution spectra from eight x - ray binaries obtained with the _ chandra _ high energy transmission grating spectrometer  , we proceed to benchmark the atomic data in the model particularly in the neon k - edge region. compared with previous photoabsorption models, which solely rely on neutral species  , the inclusion of ions leads to improved spectral fits.   fit parameters comprise the column densities of abundant contributors that allow direct estimates of the ionization states.   ismabs is provided in the appropriate format to be implemented in widely used x - ray spectral fitting packages such as xspec, isis and sherpa.
a calculational study of the trihalomethanes chloroform ( chcl@xmath0 ) and bromoform ( chbr@xmath0 ) adsorbed on graphene is presented.   the study uses the van der waals density functional method vdw - df to obtain adsorption energies and adsorption structures for these molecules of environmental concern. in this study chloroform   is found to adsorb with the h atom pointing away from graphene, with adsorption energy 357 mev ( 34.4 kj / mol ). for bromoform   the calculated adsorption energy is 404 mev ( 39.0 kj / mol ).   the corrugation of graphene as seen by chloroform is small, the difference in adsorption energy along the graphene plane is less than 6 mev.
we consider non - stationary spherically symmetric @xmath0-dimensional charged black holes with varying mass @xmath1 and/or electric charge @xmath2, described by generic charged vaidya metrics with cosmological constant @xmath3 in double null coordinates, and perform a comprehensive numerical analysis of the fundamental quasinormal modes ( qnm ) for minimally coupled scalar fields.   we show that the `` instantaneous '' quasinormal frequencies exhibit the same sort of non - stationary behavior reported previously for the four - dimensional uncharged case with @xmath4.   such property seems to be very robust, independent of the spacetime dimension and of the metric parameters, provided they be consistent with the existence of an event horizon.   the study of time dependent reissner - nordstrm black holes allows us to go a step further and quantify the deviation of the stationary regime for qnm with respect to charge variations as well.   we also look for signatures in the quasinormal frequencies from the creation of a reissner - nordstrm naked spacetime singularity.   even though one should expect the breakdown of our approach in the presence of naked singularities, we show that it is possible, in principle, to obtain some information about the naked singularity from the qnm frequencies, in agreement with the previous results of ishibashi and hosoya showing that it would be indeed possible to have regular scattering from naked singularities.
we adopt the ramsey s method of separated oscillatory fields to study coherences of the mechanical system in an optomechanical resonator.   the high resolution ramsey fringes are observed in the emission optical field, when two pulses separated in time are applied.   we develop a theory to describe the transient optomechanical behavior underlying the ramsey fringes.   we also perform the experimental demonstration using a silica microresonator.   the method is versatile and can be adopted to different types of mechanical resonators, electromechanical resonators.
systems with a bulk first - order transition can display diverging correlation lengths close to a surface.   this surface induced disordering yields a special type of surface criticality. using extensive numerical simulations we study surface quantities in the two - dimensional potts model with a large number of states @xmath0 which undergoes a discontinuous bulk transition.   the surface critical exponents are thereby found to depend on the value of @xmath0, which is in contrast to prior claims that these exponents should be universal and independent of @xmath0.   it follows that surface induced disordering at first - order transitions is characterized by exponents that depend on the details of the model.   # 1#1 # 1f
we study propagation of short laser pulses in a bose - einstein condensate taking into account dispersive effects under the conditions for electromagnetically induced transparency.   we calculate dispersion coefficients using typical experimental parameters of slow - light schemes in condensates. by numerically propagating the laser pulse, and referring to theoretical estimations,   we determine the conditions for which dispersion starts to introduce distortions on the pulse shape.
we report on a new xmm - newton observation of ngc 247 from december 2009.   the galaxy contains a supersoft, ultraluminous x - ray source ( ulx ) whose spectrum consists of a thermal component with a temperature about 0.1  kev and a power - law tail with a photon index around 2.5.   the thermal emission is absolutely the dominant component, contributing 96% of the total luminosity in the 0.3 - 10 kev band.   variability is detected at timescales of @xmath0  s and longer with a @xmath1 power spectrum.   these properties are consistent with black hole binaries in the thermal state and suggest the presence of an intermediate mass black hole of at least 600 solar masses.   however, the integrated rms power is much higher than typically found in the thermal state.   an alternative explanation of the emission could be a photosphere with a radius about @xmath2  cm.   a possible absorption feature around 1  kev is detected, which may be due to absorption of highly ionized winds.   x - ray sources within the disk of ngc 247 have a luminosity function consistent with that found in low mass x - ray binaries.   we confirm previous results that x - rays from the quasar phl  6625 may be absorbed by gas in ngc 247, mainly at energies below 0.3  kev.
we consider a quantum memory scheme based on the conversion of a signal pulse into a long - lived spin coherence via stimulated off - resonant raman process. for a storing medium consisting of alkali atoms  , we have calculated the autler - townes resonance structure created by a strong control field. by taking into account the upper hyperfine states of the @xmath0 optical transition  , we show important deviations from the predictions of the usual three - level @xmath1-scheme approximation and we demonstrate an enhancement of the process for particular detunings of the control.   we estimate the memory efficiency one can obtain using this configuration.
the strongly damping - dependent nonlinear dynamical response of classical superparamagnets is investigated by means of an analytical approach. using rigorous balance equations for the spin occupation numbers a simple approximate expression   is derived for the nonlinear susceptibility.   the results are in good agreement with those obtained from the exact ( continued - fraction ) solution of the fokker   planck equation.   the formula obtained could be of assistance in the modelling of the experimental data and the determination of the damping coefficient in superparamagnets.
radiative transfer equation in plane parallel geometry and kompaneets equation is solved simultaneously to obtain theoretical spectrum of 1 - 125 kev photon energy range.   diffuse radiation field is calculated using time - independent radiative transfer equation in plane parallel geometry, which is developed using discrete space theory ( dst ) of radiative transfer in a homogeneous medium for different optical depths.   we assumed free - free emission and absorption and emission due to electron gas to be operating in the medium.   the three terms @xmath0 and @xmath1 where @xmath2 is photon phase density and @xmath3, in kompaneets equation and those due to free - free emission are utilized to calculate the change in the photon phase density in a hot electron gas.   two types of incident radiation are considered : ( 1 ) isotropic radiation with the modified black body radiation @xmath4  and ( 2 ) anisotropic radiation which is angle dependent.   the emergent radiation at @xmath5 and reflected radiation @xmath6 are calculated by using the diffuse radiation from the medium.   the emergent and reflected radiation contain the free - free emission and emission from the hot electron gas.   kompaneets equation gives the changes in photon phase densities in different types of media.   although the initial spectrum is angle dependent, the kompaneets equation gives a spectrum which is angle independent after several compton scattering times.   diffuse radiation   kompaneets equation  radiative transfer  x - rays
we investigate a circular cavity billiard within which a pair of identical hard disks of smaller but finite size is confined.   each disk shows a free motion except when bouncing elastically with its partner and with the boundary wall. despite its circular symmetry, this system is nonintegrable and almost chaotic because of the ( short - range ) interaction between the disks.   we quantize the system by incorporating the excluded volume effect for the wavefunction.   eigenvalues and eigenfunctions are obtained by tuning the relative size between the disks and the billiard.   we define the volume @xmath0 of the cavity and the pressure @xmath1, i.e., the derivative of each eigenvalue with respect to @xmath0.   reflecting the fact that the energy spectra of eigenvalues versus the disk size show a multitude of level repulsions, @xmath2 characteristics shows the anomalous fluctuations accompanied by many van der waals - like peaks in each of individual excited eigenstates taken as a quasi - equilibrium.   for each eigenstate, we calculate the expectation values of the square distance between two disks, and point out their relationship with the pressure fluctuations.
mandelbrot introduced the concept of fractals to describe the non - euclidean shape of many aspects of the natural world. in the time series context   he proposed the use of fractional brownian motion ( fbm ) to model non - negligible temporal persistence, the   joseph effect " ; and lvy flights to quantify large discontinuities, the  noah effect ". in space physics, both effects are manifested in the intermittency and long - range correlation which are by now well - established features of geomagnetic indices and their solar wind drivers. in order to capture and quantify the noah and joseph effects in one compact model we propose the application of the  bridging " fractional lvy motion ( flm ) to space physics.   we perform an initial evaluation of some previous scaling results in this paradigm, and show how flm can model the previously observed exponents.   we suggest some new directions for the future.
we propose a version of chaotic inflation, in which a fundamental scale @xmath0, well below the planck scale @xmath1, fixes the initial value of the effective potential.   if this scale happens to be the scale of grand unified theories, there are just enough e - foldings of inflation.   an initial epoch of fast - roll breaks scale - invariance at the largest observable scales.
the predictive properties of a retina are studied by measuring the mutual information ( mi ) between its stimulation and the corresponding firing rates while it is being probed by a train of short pulses with stochastic intervals.   features of the measured mi at various time shifts between the stimulation and the response are used to characterize the predictive properties of the retina. by varying the statistical properties of the pulse train,   our experiments show that a retina has the ability to predict future events of the stimulation if the information rate of the stimulation is low enough.   also, this predictive property of the retina occurs at a time scale similar to the well established anticipative phenomenon of omitted stimulus response in a retina.   furthermore, a retina can make use of its predictive ability to distinguish between time series created by an ornsteinuhlenbeck and a hidden markovian process.
we present follow - up observations at 5, 8 and 30 ghz of the k - band northern wide survey ( knows ) 20 ghz bright sample, performed with the 32-m medicina radio telescope and the 32-m toru radio telescope.   the knows sources were selected in the northern polar cap ( @xmath0 ) and have a flux density limit s@xmath1 115 mjy.   we include nvss 1.4 ghz measurements to derive the source radio spectra between 1.4 and 30 ghz. based on optical identifications, 68 per cent of   the sources are qsos and 27 per cent are radio galaxies.   a redshift measurement is available for 58 per cent of the sources.   the radio spectral properties of the different source populations are found to be in agreement with those of other high - frequency selected samples.       galaxies : active  radio continuum : galaxies  radio continuum : general.
we study the spectrum and average mass composition of cosmic rays with primary energies between @xmath0ev and @xmath1ev using a hybrid detector consisting of the high resolution fly s eye ( hires ) prototype and the mia muon array.   measurements have been made of the change in the depth of shower maximum as a function of energy.   a complete monte carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing from a heavier to a lighter composition in this energy range.   the spectrum is consistent with earlier fly s eye measurements and supports the previously found steepening near @xmath2ev.   = 0.2 in
the full adhm - nahm formalism is employed to find exact higher charge caloron solutions with non - trivial holonomy, extended beyond the axially symmetric solutions found earlier.   particularly interesting is the case where the constituent monopoles, that make up these solutions, are not necessarily well - separated.   this is worked out in detail for charge 2.   we resolve the structure of the extended core, which was previously localized only through the singularity structure of the zero - mode density in the far field limit.   we also show that this singularity structure agrees exactly with the abelian charge distribution as seen through the abelian component of the gauge field. as a by - product zero - mode densities for charge 2 magnetic monopoles are found.
a simulation of neutrons traversing a shield beneath the comet scintillator strip cosmic - veto counter is accomplished using the geant4 toolkit.   a geant4 application is written with an appropriate detector construction and a possible spectrum of neutron s energy.   the response of scintillator strips to neutrons is studied in detail.   a design of the shield is optimized to ensure the time loss concerned with fake veto signals caused by neutrons from muon captures is tolerable.   materials of shield layers are chosen, and optimum thicknesses of the layers are computed.
in the paradigm of hierarchical galaxy formation, luminous radio galaxies mark mass assembly peaks that should contain clusters of galaxies.   observations of the @xmath0 quasar 3c270.1 with the _ spitzer space telescope _ at 3.624@xmath1 m and with the 6.5-m mmt in the @xmath2- and @xmath3-bands allow detection of potential cluster members via photometric redshifts. compared with nearby control fields  , there is an excess of @xmath411 extremely red objects ( eros ) at @xmath5, consistent with a proto - cluster around the quasar.   the spectral energy distributions ( seds ) of 3/4 of the eros are better fitted with passive elliptical galaxies than with dust - reddened starbursts, and of four sources well - detected on an archival hst snapshot image, all have undisturbed morphologies. however, one ero, not covered by the hst image, is a double source with 08 separation on the @xmath2 image and a marginal ( 2@xmath6 ) 24@xmath1 m detection indicating a dust - enshrouded starburst.   the eros are more luminous than @xmath7 ( @xmath8  ab mag at @xmath9 ).
a relativistically invariant quantum theory first advanced by bakamjian and thomas has proven very useful in modeling few - body systems. for three particles or more, this approach is known formally to fail the constraint of cluster separability, whereby symmetries and conservation laws that hold for a system of particles also hold for isolated subsystems.   cluster separability can be restored by means of a recursive construction using unitary transformations, but implementation is difficult in practice, and the quantitative extent to which the bakamjian - thomas approach violates cluster separability has never been tested.   this paper provides such a test by means of a model of a scalar probe in a three - particle system for which ( 1 ) it is simple enough that there is a straightforward solution that satisfies poincar invariance and cluster separability, and ( 2 ) one can also apply the bakamjian - thomas approach.   the difference between these calculations provides a measure of the size of the corrections from the sokolov construction that are needed to restore cluster properties.   our estimates suggest that, in models based on nucleon degrees of freedom, the corrections that restore cluster properties are too small to effect calculations of observables.
we calculate the joint distribution @xmath0 of the scattering matrix @xmath1 and time - delay matrix @xmath2 of a chaotic quantum dot coupled by point contacts to metal electrodes. while @xmath1 and @xmath3 are statistically independent for ballistic coupling, they become correlated for tunnel coupling.   we relate the ensemble averages of @xmath3 and @xmath1 and thereby obtain the average density of states at the fermi level.   we apply this to a calculation of the effect of a tunnel barrier on the majorana resonance in a topological superconductor.   we find that the presence of a majorana bound state is hidden in the density of states and in the thermal conductance if even a single scattering channel has unit tunnel probability.   the electrical conductance remains sensitive to the appearance of a majorana bound state, and we calculate the variation of the average conductance through a topological phase transition. + contribution for the special issue of physica e in memory of markus bttiker.
the latest progress in calculating electroweak gauge boson production in association with qcd jets at hadron colliders is summarized.   particular emphasis is given to the recently completed qcd one - loop calculations of w+3jets and wb final states. furthermore recent developments in improving monte carlo event generators by means of combining tree - level matrix elements with parton showers is reviewed.   
we propose a practical approach to manipulate the counter - rotating ( cr ) interactions in the quantum rabi model by introducing a sinusoidal modulation to the transition frequency of the quantum two - level system in this model. by choosing appropriate modulation frequency and amplitude, enhancement and suppression of the cr interactions   can be achieved in the jaynes - cummings regime ( including both weak- and strong - coupling cases ) as well as the ultrastrong - coupling regime. in particular, we calculate the output photon emission of the cavity vacuum state under enhanced cr terms.   our results show that continuous and steady photon emission from the cavity vacuum can be observed in the jaynes - cummings regime as a consequence of this enhancement.   our approach can be realized in superconducting quantum circuits.
we show how to reconstruct a field theory from the spectrum of bound states on a topological defect.   we apply our recipe to the case of kinks in 1 + 1 dimensions with one or two bound states.   our recipe successfully yields the sine - gordon and @xmath0 field theories when suitable bound state spectra are assumed.   the recipe can also be used to globally reconstruct the inflaton potential of inflationary cosmology if the inflaton produces a topological defect.   we discuss how defects can provide `` smoking gun '' evidence for a class of inflationary models.
we observed @xmath0 43-ghz sio maser emission toward the mira variable iktauri ( iktau ) using the very long baseline array ( vlba ).   the images resulting from these observations show that sio masers form a highly elliptical ring of emission approximately @xmath1mas with an axial ratio of 1.8:1.   the major axis of this elliptical distribution is oriented at position angle of @xmath259@xmath3.   the line - of - sight velocity structure of the sio masers has an apparent axis of symmetry consistent with the elongation axis of the maser distribution.   relative to the assumed stellar velocity of 35kms@xmath4, the blue- and red - shifted masers were found to lie to the northwest and southeast of this symmetry axis respectively.   this velocity structure suggests a nw  se rotation of the sio maser shell with an equatorial velocity, which we determine to be @xmath23.6kms@xmath4.   such a nw   se rotation is in agreement with a circumstellar envelope geometry invoked to explain previous h@xmath5o and oh maser observations. in this geometry,   h@xmath5o and oh masers are preferentially created in a region of enhanced density along the ne   sw equator orthogonal to the rotation / polar axis suggested by the sio maser velocities.
several results regarding the stability and the stabilization of linear impulsive positive systems under arbitrary, constant, minimum, maximum and range dwell - time are obtained.   the proposed stability conditions characterize the pointwise decrease of a linear copositive lyapunov function and are formulated in terms of finite - dimensional or semi - infinite linear programs. to be applicable to uncertain systems and to control design, a lifting approach   is then considered in order to make the conditions affine in the matrices of the system.   the resulting stability and stabilization conditions are stated as infinite - dimensional linear programs for which three asymptotically exact approximate computational methods are proposed and compared with each other on numerical examples.   similar results are then obtained for linear positive switched systems by exploiting the possibility of reformulating a switched system as an impulsive system.   some existing stability conditions are retrieved and extended to stabilization using the proposed lifting approach.   several examples are finally given for illustration.   positive systems ; impulsive systems ; switched systems ; clock - dependent conditions
fundamental limits of the _ cognitive interference channel _ ( cic ) with two pairs of transmitter - receiver have been under exploration for several years. in this paper, we study the discrete memoryless cognitive interference channel ( dm - cic ) in which the cognitive transmitter non - causally knows the full message of the primary transmitter. the capacity of this channel is not known in general ; it is only known in some special cases.   inspired by the concept of less noisy broadcast channel ( bc ), in this work we introduce the notion of _ less noisy _ cognitive interference channel.   unlike bc, due to the inherent asymmetry of the cognitive channel, two different less noisy channels are distinguishable ; these are named the _ primary - less - noisy _ and _ cognitive - less - noisy _ channels.   we derive capacity region for the latter case by introducing inner and outer bounds on the capacity of the dm - cic and showing that these bounds coincide for the cognitive - less - noisy channel.   having established the capacity region, we prove that superposition coding is the optimal encoding technique.
hopf algebroids are generalization of hopf algebras over non - commutative base rings.   it consists of a left- and a right - bialgebroid structure related by a map called the antipode.   however, if the base ring of a hopf algebroid is commutative one does not necessarily have a hopf algebra.   meanwhile, a hopf category is the categorification of a hopf algebra.   it consists of a category enriched over a braided monoidal category such that every hom - set carries a coalgebra structure together with an antipode functor. in this article  , we will introduce the notion of a topological hopf category@xmath0 a small category whose set of objects carries a topology and whose categorical structure maps are sufficiently continuous.   the main result of this paper is to describe the relation between finitely - generated projective hopf algebroids over commutative unital @xmath1-algebras and topological coupled hopf categories of finite - type whose space of objects is compact and hausdorff.   we will accomplish this by using methods in algebraic geometry and spectral theory.   lastly, we will show that not only the two objects are tightly related, but so are their respective galois theories.    _ mathematics subject classification _ ( 2010 ) : 16t05, 14a20, 18f99, 18b40, 58b34    _ keywords _ : hopf algebroid, hopf category, galois theory.
divergence in antigen response of the immune network is discussed, based on shape - space modelling.   the present model extends the shape - space model by introducing the evolution of specificity of idiotypes.   when the amount of external antigen increases, stability of the immune network changes and the network responds to the antigen.   it is shown that specific and non - specific responses emerge as a function of antigen levels.   a specific response is observed with a fixed point attractor, and a non - specific response is observed with a long - lived chaotic transient state of the lymphocyte population dynamics.   the network topology also changes between these two states.   the relevance of such a long - lived transient state is discussed with respect to immune function.    
this paper discusses the potential of graphics processing units ( gpus ) in high - dimensional optimization problems.   a single gpu card with hundreds of arithmetic cores can be inserted in a personal computer and dramatically accelerates many statistical algorithms. to exploit these devices   fully, optimization algorithms should reduce to multiple parallel tasks, each accessing a limited amount of data.   these criteria favor em and mm algorithms that separate parameters and data. to a lesser extent block relaxation and coordinate descent and ascent also qualify.   we demonstrate the utility of gpus in nonnegative matrix factorization, pet image reconstruction, and multidimensional scaling.   speedups of 100 fold can easily be attained. over the next decade, gpus will fundamentally alter the landscape of computational statistics.   it is time for more statisticians to get on - board.   ,
this article reviews recent developments in quantum fluid dynamics and quantum turbulence ( qt ) for superfluid helium and atomic bose - einstein condensates.   quantum turbulence was discovered in superfluid @xmath0he in the 1950s, but the field moved in a new direction starting around the mid 1990s.   quantum turbulence is comprised of quantized vortices that are definite topological defects arising from the order parameter appearing in bose - einstein condensation. hence qt is expected to yield a simpler model of turbulence than does conventional turbulence. a general introduction to this issue and a brief review of the basic concepts   are followed by a description of vortex lattice formation in a rotating atomic bose - einstein condensate, typical of quantum fluid dynamics.   then we discuss recent developments in qt of superfluid helium such as the energy spectra and dissipative mechanisms at low temperatures, qt created by vibrating structures, and the visualization of qt. as an application of these ideas  , we end with a discussion of qt in atomic bose - einstein condensates.    quantum turbulence ; quantum fluid dynamics ; quantized vortex ; superfluid helium ; bose - einstein condensation
we present time - resolved hst ultraviolet spectroscopy and ground - based optical photometry of the dwarf nova ip pegasi in a quiescent state.   the observations were obtained prior to an eclipse, when the bright spot caused by the impact of the accretion stream with the edge of the disk dominates the light output.   the optical light curve is fairly strongly correlated with the uv spectrophotometric flux curve.   an unusual emission - like feature near 1820    in the uv spectrum of ip peg is likely to be a manifestation of the `` curtain. ''   composite spectra constructed from the peaks and troughs of flickers in the light curve show substantial differences.   the spectrum of the flickers ( i.e., peaks minus troughs ) is not adequately modelled by a simple blackbody, suggesting that a more sophisticated model is appropriate.   we perform a cross - correlation analysis of the variability in spectrophotometric flux curves of the uv continuum and prominent uv emission lines ( @xmath0, @xmath1, @xmath2 ). the continuum and lines   are not correlated, suggesting that they are produced separately.   the and lines are moderately correlated with each other, but neither line is correlated with, suggesting that the latter forms in a different region than the former.   we briefly discuss a qualitative model for the geometry of the emission regions in ip peg that is consistent with the observed behavior of the uv lines and continuum.
signature of phase coherence on the electric and magnetic response of @xmath0 non - connected aharonov - bohm rings is measured by a resonant method at 350 mhz between 20 mk and 500 mk.   the rings are etched in a gaas - algaas heterojunction.   both quantities exhibit an oscillating behaviour with a periodicity consistent with half a flux quantum @xmath1 in a ring.   we find that electric screening is enhanced when time reversal symmetry is broken by magnetic field, leading to a _ positive _ magnetopolarisability, in agreement with theoretical predictions for isolated rings at finite frequency.   temperature and electronic density dependence are investigated.   the dissipative part of the electric response, the electric absorption, is also measured and leads to a _ negative _ magnetoconductance.   the magnetic orbital response of the very same rings is also investigated.   it is consistent with _   diamagnetic _ persistent currents of 0.25 na.   this magnetic response is an order of magnitude smaller than the electric one, in qualitative agreement with theoretical expectations.
using the morlet continuous wavelet transform on data over the period 1871 - 1990, it is found that the global wavelet cross spectra between two solar activity indices and seven major indian monsoon rainfall time series show significant power around the period of the 11 year solar cycle, passing the @xmath0 test of significance proposed by torrence and compo ( 1998 ) at levels exceeding @xmath1 in 10 out of the 14 cases studied.   furthermore two distinct epochs are found in the computed cross - spectrum, the transition between them occurring around the decade 1915 - 1925, beyond which solar activity parameters show a significant increase. by comparison between selected periods of three cycles in solar activity in each of the two epochs  , it is shown that the average rainfall is higher in all seven rainfall indices during periods of greater solar activity, at _ z_-test confidence levels of @xmath1 or greater in three of them.
    charm production from the direct reconstruction of @xmath0 ( @xmath1 up to 2 gev/@xmath2 ) and indirect lepton measurements via charm semileptonic decays ( @xmath3 at 0.9<@xmath4<5.0 gev/@xmath2 and @xmath5 at 0.17<@xmath6<0.25 gev/@xmath2 ) at @xmath7 gev au+au collisions are analyzed.   the transverse momentum ( @xmath4 ) spectra and the nuclear modification factors for @xmath0 and for leptons from heavy flavor decays is presented.   scaling of charm cross - section with number of binary collisions at @xmath7 gev from d+au to au+au collisions is reported.
we present a computation of elastic energy loss of hard partons traversing the bulk hydrodynamical medium created in ultrarelativistic heavy - ion collisions.   the model is based on perturbative quantum chromodynamics ( pqcd ) cross sections for @xmath0 processes in which a hard incoming parton is assumed to interact with a thermal parton from the medium.   we model the interactions of this type in a monte - carlo framework to account properly for exact energy - momentum conservation, non - eikonal parton propagation, parton conversion reactions and the possibility to create additional hard recoiling partons from the medium. for the thermodynamical properties of the medium we use a hydrodynamical evolution model.   we do not aim at a full description of high transverse momentum ( @xmath1 ) observables at this point.   rather, we view the model as a starting point in obtaining a baseline of what to expect under the assumptions that the medium is describable by thermal quasifree partons and that their pqcd interactions with the high - energy partons are independent.   deviations from this baseline then call for more sophisticated medium description, as well as inclusion of higher - order processes and coherence effects in the pqcd scatterings.
we investigate the connections between microscopic chaos, defined on a dynamical level and arising from collisions between molecules, and diffusion, characterized by a mean square displacement proportional to the time.   we use a number of models involving a single particle moving in two dimensions and colliding with fixed scatterers. we find that a number of microscopically nonchaotic models exhibit diffusion, and that the standard methods of chaotic time series analysis are ill suited to the problem of distinguishing between chaotic and nonchaotic microscopic dynamics.   however, we show that periodic orbits play an important role in our models, in that their different properties in our chaotic and nonchaotic models can be used to distinguish them at the level of time series analysis, and in systems with absorbing boundaries.   our findings are relevant to experiments aimed at verifying the existence of chaoticity and related dynamical properties on a microscopic level in diffusive systems.
this is a short review of monte carlo methods for approximating filter distributions in state space models.   the basic algorithm and different strategies to reduce imbalance of the weights are discussed.   finally, methods for more difficult problems like smoothing and parameter estimation and applications outside the state space model context are presented.
we study the applicability of a set of texture descriptors introduced in recent work by the author to texture - based segmentation of images.   the texture descriptors under investigation result from applying graph indices from quantitative graph theory to graphs encoding the local structure of images.   the underlying graphs arise from the computation of morphological amoebas as structuring elements for adaptive morphology, either as weighted or unweighted dijkstra search trees or as edge - weighted pixel graphs within structuring elements. in the present paper we focus on texture descriptors in which the graph indices are entropy - based, and use them in a geodesic active contour framework for image segmentation.   experiments on several synthetic and one real - world image are shown to demonstrate texture segmentation by this approach.   forthermore, we undertake an attempt to analyse selected entropy - based texture descriptors with regard to what information about texture they actually encode.   whereas this analysis uses some heuristic assumptions, it indicates that the graph - based texture descriptors are related to fractal dimension measures that have been proven useful in texture analysis.    * keywords : * texture segmentation @xmath0 texture descriptors @xmath0   graph entropy @xmath0 geodesic active contours @xmath0 fractal dimension
spherical truncations of coulomb interactions in standard models for water permit efficient molecular simulations and can give remarkably accurate results for the structure of the uniform liquid.   however truncations are known to produce significant errors in nonuniform systems, particularly for electrostatic properties.   local molecular field ( lmf ) theory corrects such truncations by use of an effective or restructured electrostatic potential that accounts for effects of the remaining long - ranged interactions through a density - weighted mean field average and satisfies a modified poisson s equation defined with a gaussian - smoothed charge density.   we apply lmf theory to three simple molecular systems that exhibit different aspects of the failure of a naive application of spherical truncations  water confined between hydrophobic walls, water confined between atomically - corrugated hydrophilic walls, and water confined between hydrophobic walls with an applied electric field.   spherical truncations of @xmath0 fail spectacularly for the final system in particular, and lmf theory corrects the failings for all three.   further, lmf theory provides a more intuitive way to understand the balance between local hydrogen bonding and longer - ranged electrostatics in molecular simulations involving water.
the comptel instrument performed the first mapping of the 1.809 mev photons in the galaxy, triggering considerable interest in determing the sources of interstellar @xmath0al.   the predicted @xmath0al is too low compared to the observation, for a better understanding more accurate rates for the @xmath1 reaction are required.   + the @xmath1 reaction has been investigated at the resonances at e@xmath2 is the resonance energy in the center of mass system.]@xmath3 kev at ruhr - universitt - bochum using a tandem accelerator and a @xmath4 nai detector.   in addition the resonance at e@xmath5 kev has been measured deep underground laboratory at laboratori nazionali del gran sasso, exploiting the strong suppression of cosmic background.   this low resonance has been studied with the 400 kv luna accelerator and a hpge detector.   the preliminary results of the resonance strengths will be reported.
we treat three - dimensional bosonic clusters with up to @xmath0 atoms, interacting additively through two - body van der waals potentials, in the near - threshold regime.   our study includes super - borromean systems with @xmath1 atoms for which all subsystems are unbound. we determine the energetics and structural properties such as the expectation value of the interparticle distance as a function of the coupling strength.   it has been shown that the coupling strength @xmath2, for which the @xmath1-body system becomes unbound, is bounded by the coupling constant @xmath3, for which the next smaller system with @xmath4 atoms becomes unbound, i.e., @xmath5. by fitting our numerically determined ground state energies to a simple functional form with three fitting parameters, we determine the relationship between @xmath6 and @xmath3.   our trimer and tetramer energies fall on the so - called tjon line, which has been studied in nuclear physics.   we confirm the existence of generalized tjon lines for larger clusters.   signatures of the universal behavior of weakly - bound three - dimensional clusters can possibly be observed in ultracold bose gases.
a fully abstract and universal domain model for modal transition systems and refinement, developed in @xcite, is shown to be a maximal - points space model for the bisimulation quotient of labelled transition systems over a finite set of events. in this domain model   we prove that this quotient is a stone space whose compact, zero - dimensional, and ultra - metrizable hausdorff topology measures the degree of bisimilarity and that image - finite labelled transition systems are dense. using this compactness we show that the set of labelled transition systems that refine a modal transition system, its `` set of implementations, '' is compact and derive a compactness theorem for hennessy - milner logic on such implementation sets.   these results extend to systems that also have partially specified state propositions, unify existing denotational, operational, and metric semantics on partial processes, render robust consistency measures for modal transition systems, and yield an abstract interpretation of compact sets of labelled transition systems as scott - closed sets of modal transition systems.
when using fe as a surrogate for `` metallicity '', the metallicity is best represented by the dominant species of fe.   accordingly, we have derived a new globular cluster metallicity scale based on the equivalent widths of fe  ii lines measured from high resolution spectra of giant stars.   the scale is primarily based on the results of analyses by the lick - texas group of 149 stars in 11 clusters, supplemented by other high resolution studies in five additional clusters.   we also derive _ ab initio _ the true distance moduli for m3, m5, m13, m15, and m92 as a means of setting stellar surface gravities.   we find that @xmath0 is correlated linearly with @xmath1, the reduced strength of the near - infrared ca  ii triplet defined by rutledge et al ( 1997 ), although the correlation coefficients depend on the stellar atmosphere model employed.   in addition to the 66 globular cluster metallicity estimates presented in a recent pasp review, we present here an additional 39 globular cluster metallicity estimates based on transformations from q39, the photometric index defined by zinn ( 1980 ).       a&a
in @xcite, necessary and sufficient conditions in terms of variational inequalities are introduced to characterize minimizers of convex set  valued functions with values in a conlinear space.   similar results are proved in @xcite for a weaker concept of minimizers and weaker variational inequalities.   the implications are proved using scalarization techniques that eventually provide original problems, not fully equivalent to the set - valued counterparts.   therefore, we try, in the course of this note, to close the network among the various notions proposed. more specifically, we prove that a minimizer is always a weak minimizer, and a solution to the stronger variational inequality always also a solution to the weak variational inequality of the same type. as a special case   we obtain a complete characterization of efficiency and weak efficiency in vector optimization by set - valued variational inequalities and their scalarizations.   indeed this might eventually prove the usefulness of the set optimization approach to renew the study of vector optimization.   set optimization, variational inequalities, dini derivative    49j40, 49j53, 58c06, 58e30
in this paper, we construct two component dark matter model and revisit fine - tuning, unitarity and vacuum stability problem in this framework. through higgs - portal interactions,   the additional scalar and vector singlet field can interact with the sm particles.   the parameter space of the model are severely constraint by observed relic density and direct detection experiments.   we found that, unlike the sm, the fine - tuning problem is relaxed due to the modified veltman condition.   the vacuum stability problem is addressed, the additional contributions from two dm singlets to the @xmath0 function make the higgs quartic coupling @xmath1 be positive up to planck scale in some parameter space.
the collective behavior of molecular motor proteins have been investigated in the literature using models to describe the long - time dynamics of a unidimensional continuum motor distribution. here, we consider the phenomena related to the transport of particles ( vesicles, organelles, virus, etc ) in the realm of these continuum motor systems.   we argue that cargo movement may result from its ability to perturb the existing motor distribution and to _ surf _ at the resulting shock waves separating regions of different motor densities within the transient regime.  in this case, the observed bidirectionality of cargo movement is naturally associated with reversals of shocks directions.   comparison of the quantitative results predicted by this model with available data for cargo velocity allows us to suggest that geometrical characteristics of the transported particle shall determine the extension and intensity of the perturbation it produces and thus, its dynamics.   possible implications of these ideas to virus movement at the cell body are discussed in connection with their distinguished morphological characteristics.    _   key words _ : collective effects of molecular motors ; cargo transport ; non - linear partial differential equations ; shock waves.
we study the prospects of discovering cp - violation in the production of @xmath0 leptons in the reaction @xmath1 at tesla, an @xmath2 linear collider with center - of - mass energies of 500 or even 800 gev.   non - vanishing expectation values of certain correlations between the momenta of the decay products of the two @xmath0 leptons would signal the presence of cp - violation beyond the standard model.   we study how longitudinal beam polarization of the electron and positron beams will enhance these correlations.   we find that t - odd and t - even vector correlations are well suited for the measurements of the real and imaginary parts of the electric dipole form factors.   we expect measurements of the real part with a precision of roughly @xmath3  e - cm and of the imaginary part of @xmath4  e - cm.   this compares well with the size of the expected effects in many extensions of the standard model.   + iisc - cts-02/02    * b.  ananthanarayan * + centre for theoretical studies, indian institute of science, + bangalore 560 012, india +    * saurabh d.  rindani * + theory group, physical research laboratory, + navrangpura, ahmedabad 380 009, india +    * achim stahl * + desy, platanenallee 6, + 15738 zeuthen, germany
we investigate the long - time evolution of weakly perturbed single - site breathers ( localized stationary states ) in the discrete nonlinear schrdinger ( dnls ) equation.   the perturbations we consider correspond to time - periodic solutions of the linearized equations around the breather, and can be either ( i ) spatially localized, or ( ii ) spatially extended. for case ( i ), which corresponds to the excitation of an internal mode of the breather, we find that the nonlinear interaction between the breather and its internal mode always leads to a slow growth of the breather amplitude and frequency. in case ( ii ), corresponding to interaction between the breather and a standing - wave phonon, the breather will grow provided that the wave vector of the phonon is such that the generation of radiating higher - harmonics at the breather is possible. in other cases, breather decay is observed.   this condition yields a limit value for the breather frequency above which no further growth is possible.   we also discuss another mechanism for breather growth and destruction which becomes important when the amplitude of the perturbation is non - negligible, and which originates from the oscillatory instabilities of the nonlinear standing - wave phonons.
we present a combined x - ray and optical analysis of the abcg 85/87/89 complex of clusters of galaxies, based on the rosat pspc image, optical photometric catalogues ( slezak et al. 1998 ), and an optical redshift catalogue ( durret et al. 1998 ). from this combined data   set, we find striking alignments at all scales at pa@xmath0160. at small scales, the cd galaxy in abcg 85 and the brightest galaxies in the cluster are aligned along this pa. at a larger scale,   x - ray emission defines a comparable pa south - southeast of abcg 85 towards abcg 87, with a patchy x - ray structure very different from the regular shape of the optical galaxy distribution in abcg 87.   the galaxy velocities in the abcg 87 region show the existence of subgroups, which all have an x - ray counterpart, and seem to be falling onto abcg 85 along a filament almost perpendicular to the plane of the sky.    to the west of abcg 85, abcg 89 appears as a significant galaxy density enhancement, but is barely detected at x - ray wavelengths.   the galaxy velocities reveal that in fact this is not a cluster but two groups with very different velocities superimposed along the line of sight.   these two groups appear to be located in intersecting sheets on opposite sides of a large bubble.    these data and their interpretation   reinforce the cosmological scenario in which matter, including galaxies, groups and gas, falls onto the cluster along a filament.
current - induced dynamics in spin valves including composite free layer with antiferromagnetic interlayer exchange coupling is studied theoretically within the diffusive transport regime.   we show that current - induced dynamics of a synthetic antiferromagnet is significantly different from dynamics of a synthetic ferrimagnet. from macrospin simulations we obtain conditions for switching the composite free layer, as well as for appearance of various self - sustained dynamical modes.   numerical simulations are compared with simple analytical models of critical current based on linearized landau - lifshitz - gilbert equation.
a relativistic version of cold emission of electrons in presence of strong magnetic field, relevant for strongly magnetized neutron stars is obtained.   it is found that in this scenario, a scalar type potential barrier does not allow quantum tunneling through the surface. whereas, in presence of a vector type surface barrier, the probability of electron emission is much larger compared to the original fowler - nordheim cold emission of electrons.   it is found that the relativistic version in presence of strong magnetic field does not follow exponential decay.
we discuss the spectral character of lyman  limit  selected, star  forming galaxies at @xmath0. the rest   frame uv spectra of these faint galaxies may show ly@xmath1 in either absorption or emission, probably depending upon their local ism content and geometry.   other uv interstellar resonance absorption lines show considerable variation in strength, likely related to differences in the galactic metal abundances.   we present initial results on @xmath2drop galaxies, generally at @xmath3.   our low   resolution spectrograms show no measurable flux below the redshifted lyman limit ( 912 ).   thus, it is likely that normal, star  forming galaxies at early cosmic epochs did not significantly contribute to the metagalactic ionizing radiation field.
since their discovery in 1973, gamma - ray bursts ( grbs ) have remained for many years one of the most elusive mysteries in high energy - astrophysics.   the main problem regarding the nature of grbs has usually been the lack of knowledge of their distance scale.   about 300 grbs are detected annually by batse in the full sky, but only a few of them can be localized accurately to less than half a degree. for many years, follow - up observations by other satellites and ground - based telescopes were conducted, but no counterparts at other wavelengths were found.   the breakthrough took place in 1997, thanks to the observation by _   bepposax _ and _ rossixte _ of the fading x - ray emission that follows the more energetic gamma - ray photons once the grb event has ended.   this emission ( the afterglow ) extends at longer wavelengths, and the good accuracy in the position determination by _   bepposax _ has led to the discovery of the first optical counterparts -for grb 970228, grb 970508, and grb 971214-, greatly improving our understanding of these puzzling sources.   now it is widely accepted that most bursts originate at cosmological distances but the final solution of the grb problem is still far away. + key  words : multiwavelength observations ; gamma - ray bursts.
with the advent of high - resolution high - sensitivity observations, spiral patterns have been revealed around several asymptotic giant branch ( agb ) stars.   such patterns can provide possible evidence for the existence of central binary stars embedded in outflowing circumstellar envelopes. here, we suggest the viability of explaining the previously observed incomplete ring - like patterns with the spiral - shell structure due to the motion of ( unknown ) binary components viewed at an inclination with respect to the orbital plane.   we describe a method of extracting such spiral - shells from an incomplete ring - like pattern to place constraints on the characteristics of the central binary stars.   the use of gas kinematics is essential in facilitating a detailed modeling for the three - dimensional structure of the circumstellar pattern.   we show that a hydrodynamic radiative transfer model can reproduce the structure of the hc@xmath0n molecular line emission of the extreme carbon star, cit 6.   this method can be applied to other sources in the agb phase and to the outer ring - like patterns of pre - planetary nebulae for probing the existence of embedded binary stars, which are highly anticipated with future observations using the atacama large millimeter / submillimeter array.
the time it takes a quantum system to complete a tunneling event ( which in the case of cross - barrier tunneling can be viewed as the time spent in a classically forbidden area ) is related to the time required for a state to evolve to an orthogonal state, and an observation, i.e., a quantum mechanical projection on a particular basis, is required to distinguish one state from another.   we have performed time - resolved measurements of landau - zener tunneling of bose - einstein condensates in accelerated optical lattices, clearly resolving the steplike time dependence of the band populations.   the use of different protocols enabled us to access the tunneling probability, in two different bases, namely, the adiabatic basis and the diabatic basis.   the adiabatic basis corresponds to the eigenstates of the lattice, and the diabatic one to the free - particle momentum eigenstates.   our findings pave the way towards more quantitative studies of the tunneling time for lz transitions, which are of current interest in the context of optimal quantum control and the quantum speed limit.
we use high resolution cosmological hydrodynamical simulations to demonstrate that cold flow gas accretion, particularly along filaments, modifies the standard picture of gas accretion and cooling onto galaxy disks. in the standard picture, all gas is initially heated to the virial temperature of the galaxy as it enters the virial radius.   low mass galaxies are instead dominated by accretion of gas that stays well below the virial temperature, and even when a hot halo is able to develop in more massive galaxies there exist dense filaments that penetrate inside of the virial radius and deliver cold gas to the central galaxy. for galaxies up to @xmath0l@xmath1, this cold accretion gas is responsible for the star formation in the disk at all times to the present. even for galaxies at higher masses, cold flows dominate the growth of the disk at early times. within this modified picture, galaxies are able to accrete a large mass of cold gas, with lower initial gas temperatures leading to shorter cooling times to reach the disk. although star formation in the disk is mitigated by supernovae feedback, the short cooling times allow for the growth of stellar disks at higher redshifts than predicted by the standard model.
we present a study of the globular cluster systems of two edge  on spiral galaxies, ngc  4565 and ngc  5907, from wfpc2 images in the f450w and f814w filters.   the globular cluster systems of both galaxies appear to be similar to the galactic globular cluster system.   in particular, we derive total numbers of globular clusters of @xmath0 and @xmath1 ( where the first are statistical, the second potential systematic errors ) for ngc  4565 and ngc  5907, respectively.   this determination is based on a comparison to the milky way system, for which we adopt a total number of globular clusters of @xmath2.   the specific frequency of both galaxies is @xmath3 : indistinguishable from the value for the milky way.   the similarity in the globular cluster systems of the two galaxies is noteworthy since they have significantly different thick disks and bulge - to - disk ratios.   this would suggest that these two components do not play a major role in the building up of a globular cluster system around late  type galaxies.
the dependence of the unfolding pathway of proteins on the pulling speed is investigated.   this is done by introducing a simple one - dimensional chain comprising @xmath0 units, with different characteristic bistable free energies.   these units represent either each of the modules in a modular protein or each of the intermediate `` unfoldons '' in a protein domain, which can be either folded or unfolded.   the system is pulled by applying a force to the last unit of the chain, and the units unravel following a preferred sequence.   we show that the unfolding sequence strongly depends on the pulling velocity @xmath1. in the simplest situation  , there appears a critical pulling speed @xmath2 : for pulling speeds @xmath3, the weakest unit unfolds first, whereas for @xmath4 it is the pulled unit that unfolds first. by means of a perturbative expansion, we find quite an accurate expression for this critical velocity.   = 4
perturbative qcd predicts the behavior of scattering at high energies and fixed ( sufficiently large ) transferred momenta in terms of the bfkl pomeron ( or short distance pomeron ).   we study the prospects for testing these predictions in two - photon processes at lep200 and a possible future @xmath0 collider.   we argue that the total cross section for scattering two photons sufficiently far off shell provides a clean probe of bfkl dynamics.   the photons act as color dipoles with small transverse size, so that the qcd interactions can be treated perturbatively.   we analyze the properties of the qcd result and the possibility of testing them experimentally.   we give an estimate of the rates expected and discuss the uncertainties of these results associated with the accuracy of the present theoretical calculations.   epsf.tex ( # 1 width # 2)=#2
an efficient optimal control theory based on the krotov method is introduced for a non - markovian open quantum system with a time - nonlocal master equation in which the control parameter and the bath correlation function are correlated.   this optimal control method is developed via a quantum dissipation formulation that transforms the time - nonlocal master equation to a set of coupled linear time - local equations of motion in an extended auxiliary liouville space. as an illustration,   the optimal control method is applied to find the control sequences for high - fidelity @xmath0-gates and identity - gates of a qubit embedded in a non - markovian bath.   @xmath0-gates and identity - gates with errors less than @xmath1 for a wide range of bath decoherence parameters can be achieved for the non - markovian open qubit system with control over only the @xmath2 term.   the control - dissipation correlation, and the memory effect of the bath are crucial in achieving the high - fidelity gates.
ultrafast laser measurements probe the non - equilibrium dynamics of excited electrons in metals with increasing temporal resolution.   electronic structure calculations can provide a detailed microscopic understanding of hot electron dynamics, but a parameter - free description of pump - probe measurements has not yet been possible, despite intensive research, because of the phenomenological treatment of electron - phonon interactions.   we present _ ab initio _ predictions of the electron - temperature dependent heat capacities and electron - phonon coupling coefficients of plasmonic metals.   we find substantial differences from free - electron and semi - empirical estimates, especially in noble metals above transient electron temperatures of 2000  k, because of the previously - neglected strong dependence of electron - phonon matrix elements on electron energy.   we also present first - principles calculations of the electron - temperature dependent dielectric response of hot electrons in plasmonic metals, including direct interband and phonon - assisted intraband transitions, facilitating complete theoretical predictions of the time - resolved optical probe signatures in ultrafast laser experiments.
the evaluation of a query over a probabilistic database boils down to computing the probability of a suitable boolean function, the lineage of the query over the database.   the method of query compilation approaches the task in two stages : first, the query lineage is implemented ( compiled ) in a circuit form where probability computation is tractable ; and second, the desired probability is computed over the compiled circuit.   a basic theoretical quest in query compilation is that of identifying pertinent classes of queries whose lineages admit compact representations over increasingly succinct, tractable circuit classes.    fostering previous work by jha and suciu @xcite and petke and razgon @xcite, we focus on queries whose   lineages admit circuit implementations with small treewidth, and investigate their compilability within tame classes of decision diagrams. in perfect analogy with the characterization of bounded circuit pathwidth by bounded obdd width @xcite, we show that a class of boolean functions has bounded circuit treewidth if and only if it has bounded sdd width.   sentential decision diagrams ( sdds ) are central in knowledge compilation, being essentially as tractable as obdds @xcite but exponentially more succinct @xcite. by incorporating constant width sdds and polynomial size sdds,   we refine the panorama of query compilation for unions of conjunctive queries with and without inequalities @xcite.
we probe the higher - order clustering of the galaxies in the final data release ( dr12 ) of the sloan digital sky survey baryon oscillation spectroscopic survey ( boss ) using the method of germ - grain minkowski functionals ( mfs ).   our sample consists of @xmath0 boss galaxies from the northern galactic cap in the redshift range @xmath1@xmath2.   we show the mfs to be sensitive to contributions up to the six - point correlation function for this data set.   we ensure with a custom angular mask that the results are more independent of boundary effects than in previous analyses of this type.   we extract the higher - order part of the mfs and quantify the difference to the case without higher - order correlations  . the resulting @xmath3 value of over @xmath4 for a modest number of degrees of freedom, @xmath5, indicates a @xmath6-sigma deviation and demonstrates that we have a highly significant signal of the non - gaussian contributions to the galaxy distribution.   this statistical power can be useful in testing models with differing higher - order correlations. comparing the galaxy data to the qpm and multidark - patchy mocks, we find that the latter better describes the observed structure. from an order - by - order decomposition   we expect that, for example, already a reduction of the amplitude of the md - patchy mock power spectrum by 5% would remove the remaining tension.       methods : data analysis  methods : statistical  cosmology : large - scale structure of universe  cosmology : observations
superluminal motion is a common feature of radio jets in powerful @xmath0-ray emitting active galactic nuclei.   conventionally, the variable emission is assumed to originate near the central supermassive black - hole where the jet is launched on parsec scales or smaller. here  , we report the discovery of superluminal radio features within a distinct flaring x - ray emitting region in the jet of the nearby radio galaxy m87 with the _ very long baseline array_. this shows that these two phenomenological hallmarks   superluminal motion and high - energy variability  are associated, and we place this activity much further ( @xmath1120 pc ) from the `` central engine '' in m87 than previously thought in relativistic jet sources.   we argue that the recent excess very high - energy tev emission from m87 reported by the h.e.s.s.   experiment originates from this variable superluminal structure, thus providing crucial insight into the production region of @xmath0-ray emission in more distant blazars.
the first results from the hi parkes all - sky survey ( hipass ) provide a spectacular view of the global hi distribution in the vicinity of the magellanic clouds and the southern milky way.   a 2400 square degree mosaic around the south celestial pole ( scp ) reveals the existence of a narrow, continuous counter - stream which leads the direction of motion of the clouds, i.e. opposite in direction to the stream.   this strongly supports the gravitational model for the stream in which the leading and trailing streams are tidally torn from the body of the magellanic clouds  . the data also reveal additional tidal features in the bridge region which appear to emanate from the lmc, and a distinct spiral structure within the lmc itself.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present a broad band x - ray observation of the cas  a supernova remnant, obtained with the 4 narrow field instruments on board the bepposax satellite.   the x - ray spectrum thus obtained spans more than two decades in energy, from @xmath0 to @xmath1kev.   the complete spectrum is fit with a two - component non - equilibrium ionization ( nei ) model plus a power - law component which dominates at the higher energies.   the influence of the hard x - ray tail on the parameters derived for the thermal emission is discussed.
we report the detection of oh satellite line masers at 1720 mhz and 1612 mhz from the nuclear region of the starburst galaxy m82.   the observations were aimed at detecting 1720 mhz maser emission from the known radio emitting snr in the nuclear region. at 1720 mhz   we detect six features above the 5@xmath0 limit set by noise, four in emission and two in absorption.   three of the emission features appear closely associated with known discrete continuum radio sources, and one of the absorption features is precisely coincident with the discrete continuum source 44.01 + 59.6.   the latter source also exhibits strong 1612 mhz emission at the same velocity.   no other 1612 mhz features were detected.   all of the 1720 mhz emission features are consistent with masers pumped by collisions with molecular hydrogen at densities between @xmath1  @xmath2 and 10@xmath3  @xmath2, and t@xmath4 between 50  k and 250  k. the absorption and emission associated with the two satellite lines in 44.01 + 59.6, together with other evidence, points to the possibility that this source is the agn in m82.
we investigate the liquid - gas phase transition of hot protoneutron stars shortly after their birth following supernova explosion and the composition and structure of hyperon - rich ( proto)neutron stars within a relativistic mean - field model where the nuclear symmetry energy has been constrained from the measured neutron skin thickness of finite nuclei.   light clusters are abundantly formed with increasing temperature well inside the neutrino - sphere for an uniform supernova matter.   liquid - gas phase transition is found to suppress the cluster yield within the coexistence phase as well as decrease considerably the neutron - proton asymmetry over a wide density range.   we find symmetry energy has a modest effect on the boundaries and the critical temperature for the liquid - gas phase transition, and the composition depends more sensitively on the number of trapped neutrinos and temperature of the protoneutron star.   the influence of hyperons in the dense interior of stars makes the overall equation of state soft.   however, neutrino trapping distinctly delays the appearance of hyperons due to abundance of electrons.   we also find that a softer symmetry energy further makes the onset of hyperon less favorable.   the resulting structures of the ( proto)neutron stars with hyperons and with liquid - gas phase transition are discussed.
we study the _ nonlinear _ gravitational collapse of a _ charged _ massless scalar - field.   we confirm the existence of oscillatory inverse power - law tails along future timelike infinity, future null infinity and along the future outer - horizon.   the _ nonlinear _ dumping exponents are in excellent agreement with the _ analytically _ predicted ones.   our results prove the analytic conjecture according to which a _ charged _ hair decays _ slower _ than a neutral one and also suggest the occurrence of mass - inflation along the cauchy horizon of a _ dynamically _ formed charged black - hole.
the line and continuum spectra of the merger galaxy arp 220 are analysed with the aim of investigating the ionizing and heating sources.   we refer to radio, optical, infrared and x - ray spectra.   the results show that in agreement with other merger galaxies, the optical lines are emitted from gas photoionised by the agn and heated by the shocks in the extended nlr.   the infrared lines are better explained by the emission from gas close to the starburst.   the starburst dominates the infrared emission.    and  lines in the far - infrared are formed in the internal region of extended clouds and are therefore absorbed, while  lines are emitted from the external edges of outflowing clouds. the o / h relative abundances are about solar and n / h are higher than solar by a factor @xmath01.5, throughout the starburst region, while in the agn extended nlr the o / h ratio is half solar.   a relatively high dust - to - gas ratio is indicated by modelling the dust reprocessed radiation peak consistently with bremsstrahlung emitted from the clouds.   the observed radio emission is thermal bremsstrahlung, while synchrotron radiation created by the fermi mechanism at the shock front is absorbed.       radiation mechanisms : general  shock waves  ism : abundances  galaxies : seyfert  galaxies : individual : arp 220
this paper continues a study on choptuik scaling in gravitational collapse of a massless complex scalar field at the threshold for black hole formation.   we perform a linear perturbation analysis of the previously derived complex critical solution, and calculate the critical exponent for black hole mass, @xmath0.   we also show that this critical solution is unstable via a growing oscillatory mode.
we review recent progress in numerical relativity simulations of black - hole ( bh ) spacetimes. following a brief summary of the methods employed in the modeling,   we summarize the key results in three major areas of bh physics : ( i ) bhs as sources of gravitational waves ( gws ), ( ii ) astrophysical systems involving bhs, and ( iii ) bhs in high - energy physics.   we conclude with a list of the most urgent tasks for numerical relativity in these three areas.    numerical relativity, black holes, gravitational wave physics, astrophysics, high - energy physics    65m06, 65m50, 65m70, 65z05
the stellar observations network group ( song ) has obtained full funding for the design, construction and implementation of a prototype telescope and instrumentation package for the first network node.   we describe the layout of such a node and its instrumentation and expected performance for radial - velocity measurements.   the instrumentation consists of a 1 m telescope, equipped with two cameras for photometry of microlensing events with the lucky - imaging technique and a high - resolution spectrograph equipped with an iodine cell for obtaining high - precision radial velocities of solar - like stars, in order to do asteroseismology.   the telescope will be located in a dome of @xmath0 m diameter, with two lucky - imaging cameras at one of the nasmyth foci and the spectrograph and instrument control computers at a coud focus, located in an adjacent container.   currently the prototype telescope and instrumentation are undergoing detailed design.   installation at the first site ( tenerife ) is expected during mid  late 2010, followed by extensive testing during 2011.
the time evolution of anharmonic molecular wave packets is investigated under the influence of the environment consisting of harmonic oscillators.   these oscillators represent photon or phonon modes and assumed to be in thermal equilibrium.   our model explicitly incorporates the fact that in the case of a nonequidistant spectrum the rates of the environment induced transitions are different for each transition.   the nonunitary time evolution is visualized by the aid of the wigner function related to the vibrational state of the molecule.   the time scale of decoherence is much shorter than that of dissipation, and gives rise to states which are mixtures of localized states along the phase space orbit of the corresponding classical particle.   this behavior is to a large extent independent of the coupling strength, the temperature of the environment and also of the initial state.
the hopfield network is reconstructed as an inverse ising problem by passing messages.   the applied susceptibility propagation algorithm is shown to improve significantly on other mean - field - type methods and extends well into the low temperature region. however, this iterative algorithm is limited by the nature of the supplied data.   its performance deteriorates as the data becomes highly magnetized, and this method finally fails in the presence of the frozen type data where at least two of its magnetizations are equal to one in absolute value. on the other hand,   a threshold behavior is observed for the susceptibility propagation algorithm and the transition from good reconstruction to poor one becomes sharper as the network size increases.
the larmor precession of a neutral spinning particle in a magnetic field confined to the region of a one dimensional - rectangular barrier is investigated for both a nonrelativistic and a relativistic incoming particle.   the spin precession serves as a clock to measure the time spent by a quantum particle traversing a potential barrier. with the help of general spin coherent   state it is explicitly shown that the precession time is equal to the dwell time in both the nonrelativistic and relativistic cases.   we also present a numerical estimation of the precession time showing an apparent superluminal tunneling.   pacs number(s ) : 03.65.xp, 03.65.ta
the propagation of a weak probe field in a laser - driven four - level atomic system is investigated.   we choose mercury as our model system, where the probe transition is in the ultraviolet region.   a high - resolution peak appears in the optical spectra due to the presence of interacting dark resonances.   we show that this narrow peak leads to superluminal light propagation with strong absorption, and thus by itself is only of limited interest.   but if in addition a weak incoherent pump field is applied to the probe transition, then the peak structure can be changed such that both sub- and superluminal light propagation or a negative group velocity can be achieved without absorption, controlled by the incoherent pumping strength.
in this article, we present a denoising algorithm to improve the interpretation and quality of scanning tunneling microscopy ( stm ) images. given the high level of self - similarity of stm images, we propose a denoising algorithm by reformulating the true estimation problem as a sparse regression, often termed sparse coding.   we introduce modifications to the algorithm to cope with the existence of artifacts, mainly dropouts, which appear in a structured way as consecutive line segments on the scanning direction.   the resulting algorithm treats the artifacts as missing data, and the estimated values outperform those algorithms that substitute the outliers by a local filtering.   we provide code implementations for both matlab and gwyddion  @xcite.
stochastic resonance ( sr ) is a well known phenomenon in dynamical systems.   it consists of the amplification and optimization of the response of a system assisted by stochastic noise.   here we carry out the first experimental study of sr in single dna hairpins which exhibit cooperatively folding / unfolding transitions under the action of an applied oscillating mechanical force with optical tweezers. by varying the frequency of the force oscillation, we investigated the folding / unfolding kinetics of dna hairpins in a periodically driven bistable free - energy potential.   we measured several sr quantifiers under varied conditions of the experimental setup such as trap stiffness and length of the molecular handles used for single - molecule manipulation.   we find that the signal - to - noise ratio ( snr ) of the spectral density of measured fluctuations in molecular extension of the dna hairpins is a good quantifier of the sr.   the frequency dependence of the snr exhibits a peak at a frequency value given by the resonance matching condition.   finally, we carried out experiments in short hairpins that show how sr might be useful to enhance the detection of conformational molecular transitions of low snr.
in theories with chiral couplings, one of the important consistency requirements is that of the cancellation of a gauge anomaly. in particular, this is one of the conditions imposed on the hypercharges in the standard model.   however, anomaly cancellation condition of the standard model looks unnatural from the perspective of a theory with extra dimensions. indeed,   if our world were embedded into an odd - dimensional space, then the full theory would be automatically anomaly free. in this paper   we discuss the physical consequences of anomaly non - cancellation for effective 4-dimensional field theory.   we demonstrate that in such a theory parallel electric and magnetic fields get modified. in particular, this happens for any particle possessing both electric charge and magnetic moment.   this effect, if observed, can serve as a _ low energy _ signature of extra dimensions. on the other hand,   if such an effect is absent or is very small, then from the point of view of any theory with extra dimensions it is just another fine - tuning and should acquire theoretical explanation.
the scaling of friction with the contact size @xmath0 and ( in)commensurabilty of nanoscopic and mesoscopic crystals on a regular substrate are investigated analytically for triangular nanocrystals on hexagonal substrates.   the crystals are assumed to be stiff, but not completely rigid.   commensurate and incommensurate configurations are identified systematically.   it is shown that three distinct friction branches coexist, an incommensurate one that does not scale with the contact size ( @xmath1 ) and two commensurate ones which scale differently ( with @xmath2 and @xmath0 ) and are associated with various combinations of commensurate and incommensurate lattice parameters and orientations.   this coexistence is a direct consequence of the two - dimensional nature of the contact layer, and such multiplicity exists in all geometries consisting of regular lattices. to demonstrate this  , the procedure is repeated for rectangular geometry.   the scaling of irregularly shaped crystals is also considered, and again three branches are found ( @xmath3 ). based on the scaling properties, a quantity is defined which can be used to classify commensurability in infinite as well as finite contacts. finally, the consequences for friction experiments on gold nanocrystals on graphite are discussed.
we consider the breaking of the global conservation of gauge field charges which are commonly thought to survive the spontaneous breakdown of gauge symmetry brought about by kalb - ramond fields.   depending on the dilaton field and also the size of the compactifying space, the global charge breaking may take place due to world sheet instantons. in going to @xmath0 dimensions   one could have a serious problem in order to produce the hierarchies between the quark and the charged lepton masses using the mass protecting charges with the green - schwartz anomaly cancellation.   various unnatural features of this type of models are discussed.  ,    green - schwarz anomaly cancellation mechanism, kalb - ramond field, world sheet instantons, wormholes 11.15.ex, 11.25.mj, 11.30.fs, 12.38.lg
we propose that future experiments aiming at the detection of deviations from the @xmath0 gravitational law on submillimetric scales can be used to test the modified newtonian dynamics theory ( mond ).   current experiments are able to test the gravitational field of masses @xmath1 1 g at distances @xmath2 200 @xmath3 m, implying that they are probing accelerations well above the mond limit ( @xmath4 1.2 @xmath5 10@xmath6 cms@xmath7 ). we show that mondian effects begin to be important at the submillimetric level for masses @xmath8 1 mg. mond makes predictions that are clearly distinguishable from those expected in a scenario with compact extra dimensions.   this will enable direct confrontation between the two theories if future experiments can improve their mass scales to the milligram level.  ,    gravitation : phenomenology, gravitation : experimental tests    04.80.cc, 04.50.+h, 95.30.sf
as a generalization of postnikov s construction , we define a map from the space of edge weights of a directed network in an annulus into a space of loops in the grassmannian.   we then show that universal poisson brackets introduced for the space of edge weights in  induce a family of poisson structures on rational - valued matrix functions and on the space of loops in the grassmannian. in the former case,   this family includes, for a particular kind of networks, the poisson bracket associated with the trigonometric r - matrix.
we present a realization of two - qubit controlled - phase gate, based on the linear and nonlinear properties of the probe and signal optical pulses in an asymmetric gaas / algaas double quantum wells.   it is shown that, in the presence of cross - phase modulation, a giant cross - kerr nonlinearity and mutually matched group velocities of the probe and signal optical pulses can be achieved while realizing the suppression of linear and self - kerr optical absorption synchronously.   these characteristics serve to exhibit an all - optical two - qubit controlled - phase gate within efficiently controllable photon - photon entanglement by semiconductor mediation.   in addition, by using just polarizing beam splitters and half - wave plates, we propose a practical experimental scheme to discriminate the maximally entangled polarization state of two - qubit through distinguishing two out of the four bell states.   this proposal potentially enables the realization of solid states mediated all - optical quantum computation and information processing.
the opera neutrino detector at the underground gran sasso laboratory ( lngs ) was designed to perform the first detection of neutrino oscillations in appearance mode, through the study of @xmath0 oscillations.   the apparatus consists of a lead / emulsion - film target complemented by electronic detectors.   it is placed in the high - energy, long - baseline cern to lngs beam ( cngs ) 730 km away from the neutrino source. in august 2006   a first run with cngs neutrinos was successfully conducted.   a first sample of neutrino events was collected, statistically consistent with the integrated beam intensity. after a brief description of the beam and of the various sub - detectors,   we report on the achievement of this milestone, presenting the first data and some analysis results.
the presence of two globular cluster subpopulations in early  type galaxies is now the norm rather than the exception. here   we present two more examples for which the host galaxy appears to have undergone a recent merger. using multi   colour keck imaging of ngc 1052 and ngc 7332 we find evidence for a bimodal globular cluster colour distribution in both galaxies, with roughly equal numbers of blue and red globular clusters.   the blue ones have similar colours to those in the milky way halo and are thus probably very old and metal  poor.   if the red gc subpopulations are at least solar metallicity, then stellar population models indicate young ages.   we discuss the origin of globular clusters within the framework of formation models.   we conclude that recent merger events in these two galaxies have had little effect on their overall gc systems.   we also derive globular cluster density profiles, global specific frequencies and in the case of ngc 1052, radial colour gradients and azimuthal distribution. in general   these globular cluster properties are normal for early  type galaxies.   globular clusters : general  galaxies : individual : ngc 1052, ngc 7332  galaxies : star clusters.
a hole spin is a potential solid - state q - bit, that may be more robust against nuclear spin induced dephasing than an electron spin. here   we propose and demonstrate the sequential preparation, control and detection of a single hole spin trapped on a self - assembled ingaas / gaas quantum dot.   the dot is embedded in a photodiode structure under an applied electric - field.   fast, triggered, initialization of a hole spin is achieved by creating a spin - polarized electron - hole pair with a picosecond laser pulse, and in an applied electric - field, waiting for the electron to tunnel leaving a spin - polarized hole.   detection of the hole spin with picosecond time resolution is achieved a second picosecond laser pulse to probe the positive trion transition, where a trion is created conditional on the hole spin to be detected as a change in photocurrent.   finally, using this setup we observe a rabi rotation of the hole - trion transition that is conditional on the hole spin, which for a pulse - area of @xmath0 can be used to impart a phase - shift of @xmath1 between the hole spin states, a non - general manipulation of the hole spin.   a. quantum dots ; d. spin dynamics ; e. coherent control code 78.67.hc, 42.50.hz, 71.35.pq
in this paper, we propose an effective search procedure that interleaves two steps : subproblem generation and subproblem solution.   we mainly focus on the first part.   it consists of a variable domain value ranking based on reduced costs. exploiting the ranking, we generate, in a limited discrepancy search tree, the most promising subproblems first.   an interesting result is that reduced costs provide a very precise ranking that allows to almost always find the optimal solution in the first generated subproblem, even if its dimension is significantly smaller than that of the original problem. concerning the proof of optimality  , we exploit a way to increase the lower bound for subproblems at higher discrepancies.   we show experimental results on the tsp and its time constrained variant to show the effectiveness of the proposed approach, but the technique could be generalized for other problems.
agent - based modeling and simulation ( abms ) is a simple and yet powerful method for simulation of interactions among individual agents. using abms,   different phenomena can be modeled and simulated without spending additional time on unnecessary complexities.   although abms is well - matured in many different fields such as economic, social, and natural phenomena, it has not received much attention in the context of mobile ad - hoc networks ( manets ). in this paper  , we present abmq, a powerful agent - based platform suitable for modeling and simulation of self - organization in wireless networks, and particularly manets. by utilizing the unique potentials of qt application framework,   abmq provides the ability to easily model and simulate self - organizing algorithms, and then reuse the codes and models developed during simulation process for building real third - party applications for several desktop and mobile platforms, which substantially decreases the development time and cost, and prevents probable bugs that can happen as a result of rewriting codes.    agent - based modeling and simulation, qt, manet, self - organization
superconductors are a striking example of a quantum phenomenon in which electrons move coherently over macroscopic distances without scattering.   the high - temperature superconducting oxides ( cuprates ) are the most studied class of superconductors, composed of two - dimensional cuo@xmath0 planes separated by other layers which control the electron concentration in the planes.   a key unresolved issue in cuprates is the relationship between superconductivity and magnetism. in this paper, we report a sharp phase boundary of static three - dimensional magnetic order in the electron - doped superconductor la@xmath1ce@xmath2cuo@xmath3   where small changes in doping or depth from the surface switch the material from superconducting to magnetic. using low - energy spin polarized muons, we find static magnetism disappears close to where superconductivity begins and well below the doping where dramatic changes in the transport properties are reported.   these results indicate a higher degree of symmetry between the electron and hole - doped cupratets than previously thought.
a new pulsar,, was discovered during a bepposax galactic plane survey on 1999 july 20 at r.a.=@xmath0, dec=@xmath1 ( j2000 ) with a 90% confidence uncertainty radius of @xmath2.   coherent pulsations were detected with a barycentric period of a @xmath3  s. the x - ray spectrum can be modeled by a power - law with a photon index of @xmath4 and absorption consistent with the galactic value in the direction of the source ( @xmath5  atom  @xmath6 ). an fe k line with a equivalent width of @xmath71.3 kev may be present in the spectrum.   the unabsorbed 210  kev flux is @xmath8  erg  @xmath6  s@xmath9.   the x - ray properties and lack of an obvious optical counterpart are consistent with a be star companion at a distance of between approximately 6 and 12  kpc which implies a luminosity of ( 415)@xmath10  erg  s@xmath9.
quantum effects are expected to disappear in the short - wavelength, semiclassical limit. as a matter of fact  , recent investigations of transport through quantum chaotic systems have demonstrated the exponential suppression of the weak localization corrections to the conductance and of the fano factor for shot - noise when the ehrenfest time @xmath0 exceeds the electronic dwell time @xmath1. on the other hand, conductance fluctuations, an effect of quantum coherence,   retain their universal value in the limit @xmath2, when the system is ideally coupled to external leads.   motivated by this intriguing result we investigate conductance fluctuations through quantum chaotic cavities coupled to external leads via ( tunnel ) barriers of arbitrary transparency @xmath3.   using the trajectory - based semiclassical theory of transport, we find a linear @xmath0-dependence of the conductance variance showing a nonmonotonous, sinusoidal behavior as a function of @xmath3.   most notably, we find an increase of the conductance fluctuations with @xmath0, above their universal value, for @xmath4.   these results, confirmed by numerical simulations, show that, contrarily to the common wisdom, effects of quantum coherence may increase in the semiclassical limit, under special circumstances.
we present a detailed study of the finite one - dimensional quantum ising chain in a transverse field in the presence of boundary magnetic fields coupled with the order - parameter spin operator.   we consider two magnetic fields located at the boundaries of the chain that have the same strength and that are aligned in the same or in the opposite direction.   we derive analytic expressions for the gap in all phases for large values of the chain length @xmath0, as a function of the boundary field strength.   we also investigate the behavior of the chain in the quantum ferromagnetic phase for oppositely aligned fields, focusing on the magnet - to - kink transition that occurs at a finite value of the magnetic field strength. at this transition   we compute analytically the finite - size crossover functions for the gap, the magnetization profile, the two - point correlation function, and the density of fermionic modes. as the magnet - to - kink   transition is equivalent to the wetting transition in two - dimensional classical ising models, our results provide new analytic predictions for the finite - size behavior of ising systems in a strip geometry at this transition.
a quantum kinetic theory for correlated charged  particle systems in strong time   dependent electromagnetic fields is developed.   our approach is based on a systematic gauge  invariant nonequilibrium green s functions formulation.   extending our previous analysis @xcite we concentrate on the selfconsistent treatment of dynamical screening and electromagnetic fields which is applicable to arbitrary nonequilibrium situations.   the resulting kinetic equation generalizes previous results to quantum plasmas with full dynamical screening and includes many   body effects.   it is, in particular, applicable to the interaction of dense plasmas with strong electromagnetic fields, including laser fields and x - rays.   furthermore, results for the modification of the plasma screening and the longitudinal field fluctuations due to the electromagnetic field are presented.
we present new deep near - infrared images of dark clouds in the perseus molecular complex.   these images show beautiful extended emission which we model as scattered ambient starlight and name `` cloudshine ''.   the brightness and color variation of cloudshine complicates the production of extinction maps, the best tracer of column density in clouds.   however, since the profile of reflected light is essentially a function of mass distribution, cloudshine provides a new way to study the structure of dark clouds.   previous work has used optical scattered light to study the density profile of tenuous clouds ; extending this technique into the infrared provides a high - resolution view into the interiors of very dense clouds, bypassing the complexities of using thermal dust emission, which is biased by grain temperature, or molecular tracers, which have complicated depletion patterns. as new wide - field infrared cameras   are used to study star - forming regions at greater depth, cloudshine will be widely observed and should be seen as a new high - resolution tool, rather than an inconvenience.
we investigate methods to vaccinate contact networks   i.e.  removing nodes in such a way that disease spreading   is hindered as much as possible  with respect to their cost - efficiency.   any real implementation of such protocols would come with costs related both to the vaccination itself, and gathering of information about the network.   disregarding this, we argue, would lead to erroneous evaluation of vaccination protocols.   we use the susceptible - infected - recovered model  the generic model for diseases making patients immune upon recovery  as our disease - spreading scenario, and analyze outbreaks on both empirical and model networks. for different relative costs,   different protocols dominate. for high vaccination costs and low costs of gathering information  , the so - called acquaintance vaccination is the most cost efficient. for other parameter values,   protocols designed for query - efficient identification of the network s largest degrees are most efficient.
in the present work, the non - spherical dust grain characteristics of comet hale - bopp are studied using the t - matrix method and the modified power law distribution function.   it is found that the observed data fits very well with the power index ( @xmath0. the best fit values of complex refractive index @xmath1 and the aspect ratio ( e ) at @xmath2 are calculated to be @xmath3 and @xmath4 at @xmath5 and @xmath6 respectively.   kerola & larson ( k - l ) analysed the same comet using the t - matrix method and the power law distribution function ( @xmath7 ), and found that the prolate grains can explain the observed polarization in a more satisfactory manner as compared to the other shapes.   but their analysis could not reproduce the negative polarization branch beyond scattering angle @xmath8.   however, the results obtained from the present work successfully generate the expected negative polarization curve beyond @xmath8 and the fitting in this case is much better than k - l s work.   so it is concluded from the present study that the use of modified power law distribution function ( with @xmath2 ) can fit the observed data in a better way, as compared to the power law distribution function used by previous authors.       comets : general  dust, extinction  scattering  polarization
we present a two - dimensional version of the classical one - dimensional kolmogorov  smirnov ( k - s ) test, extending an earlier idea due to @xcite and an implementation proposed by @xcite.   the two - dimensional k - s test is used to optimise the goodness of fit in an iterative source - detection scheme for astronomical images.   the method is applied to a _ rosat_/hri x - ray image of the post core - collapse globular cluster ngc  6397 to determine the most probable source distribution in the cluster core.   comparisons to other widely - used source detection methods, and to a _   chandra _   image of the same field, show that our iteration scheme is superior in measuring statistics - limited sources in severely crowded fields.    methods : data analysis  methods : statistical  globular clusters : individual ( ngc  6397 )  x - ray : stars
we develop a fully relativistic dwia model for photonuclear reactions using the relativistic mean field theory for the bound state and the pauli reduction of the scattering state which is calculated from a relativistic optical potential.   results for the @xmath0c@xmath1 and @xmath2o@xmath1 differential cross sections and photon asymmetries are displayed in a photon energy range between 60 and 257 mev, and compared with nonrelativistic dwia calculations.   the effects of the spinor distortion and of the effective momentum approximation for the scattering state are discussed.   the sensitivity of the model to different prescriptions for the one - body current operator is investigated.   the off - shell ambiguities are large in @xmath1 calculations, and even larger in @xmath3 knockout.   pacs numbers : 25.20.dc, 24.10.jv
it is shown that due to radiative corrections a photon having a non vanishing component of its momentum perpendicular to it, bears a non - zero magnetic moment.   all modes of propagation of the polarization operator in one loop approximation are discussed and in this field regime the dispersion equation and the corresponding magnetic moment are derived.   near the first thresholds of cyclotron resonance the photon magnetic moment has a peak larger than the electron anomalous magnetic moment.   related to this magnetic moment, the arising of some sort of photon `` dynamical mass '' and a gyromagnetic ratio are discussed.   these latter results might be interesting in an astrophysical context.
the cms collaboration at the lhc has reported a remarkable and unexpected phenomenon in very high - multiplicity high energy proton - proton collisions : a positive correlation between two particles produced at similar azimuthal angles, spanning a large range in rapidity.   we suggest that this  ridge "- like correlation may be a reflection of the rare events generated by the collision of aligned flux tubes connecting the valence quarks in the wave functions of the colliding protons.   the  spray " of particles resulting from the approximate line source produced in such inelastic collisions then gives rise to events with a strong correlation between particles produced over a large range of both positive and negative rapidity.   we suggest an additional variable that is sensitive to such a line source which is related to a commonly used measure, ellipticity.    `   slac - pub-15352 `
the retrieval behavior and thermodynamic properties of symmetrically diluted q - ising neural networks are derived and studied in replica - symmetric mean - field theory generalizing earlier works on either the fully connected or the symmetrical extremely diluted network.   capacity - gain parameter phase diagrams are obtained for the @xmath0, @xmath1 and @xmath2 state networks with uniformly distributed patterns of low activity in order to search for the effects of a gradual dilution of the synapses.   it is shown that enlarged regions of continuous changeover into a region of optimal performance are obtained for finite stochastic noise and small but finite connectivity.   the de almeida - thouless lines of stability are obtained for arbitrary connectivity, and the resulting phase diagrams are used to draw conclusions on the behavior of symmetrically diluted networks with other pattern distributions of either high or low activity.   epsf    
we report adjustable magnetic ` bouncing'and focusing of a dilute @xmath0rb bose gas.   both the condensate production and manipulation are realised using a particularly straight - forward apparatus.   the bouncing region is comprised of approximately concentric ellipsoidal magnetic equipotentials with a centre that can be adjusted vertically.   we extend, and discuss the limitations of, simple thomas - fermi and monte - carlo theoretical models for the bouncing, which at present find close agreement with the condensate s evolution.   very strong focusing has been inferred and the observation of atomic matter - wave diffraction should be possible.   prospects look bright for applications in matter - wave atom - optics, due to the very smooth nature of the mirror.
magnetic layers are narrow regions where the field direction changes sharply.   they often occur in the association with neutral points of the magnetic field.   we show that an organised field can produce these structures near a rotating black hole, and we identify them as potential sites of magnetic reconnection. to that end   we study the field lines affected by the frame - dragging effect, twisting the magnetic structure and changing the position of neutral points.   we consider oblique fields in vacuum.   we also include the possibility of translational motion of the black hole which may be relevant when the black hole is ejected from the system.   the model settings apply to the innermost regions around black holes with the ergosphere dominated by a super - equipartition magnetic field and loaded with a negligible gas content.
we compare weak and strong coupling theory of counterion - mediated electrostatic interactions between two asymmetrically charged plates with extensive monte - carlo simulations. analytical results in both weak and strong coupling limits compare excellently with simulations in their respective regimes of validity.   the system shows a surprisingly rich structure in terms of interactions between the surfaces as well as fundamental qualitative differences in behavior in the weak and the strong coupling limits.
we study target - searching processes on a percolation, on which a hunter tracks a target by smelling odors it emits.   the odor intensity is supposed to be inversely proportional to the distance it propagates.   the monte carlo simulation is performed on a 2-dimensional bond - percolation above the threshold.   having no idea of the location of the target, the hunter determines its moves only by random attempts in each direction. for lager percolation connectivity @xmath0  , it reveals a scaling law for the searching time versus the distance to the position of the target.   the scaling exponent is dependent on the sensitivity of the hunter. for smaller @xmath1,   the scaling law is broken and the probability of finding out the target significantly reduces.   the hunter seems trapped in the cluster of the percolation and can hardly reach the goal.
in the search for cp violation at the t2k and future hyper - kamiokande experiments, it is crucial to reduce the present systematic uncertainties.   the current t2k near detector, nd280, reduces the uncertainties coming from the neutrino beam and cross - section models from @xmath0 to @xmath1 in the @xmath2 appearance channel.   these residual uncertainties mostly come from intrinsic limitations of nd280 due to its difference in target material and angular acceptance with the far detector.   + in order to show evidence ( subsequently observation ) of the cp violation in the t2k phase - ii and hyper - kamiokande experiments, this paper proposes an upgrade of the nd280 detector.   it uses a 3d grid scintillator structure surrounded by time projecting chambers in order to reconstruct particles with @xmath3 acceptance.
the laplace operator in infinite quantum waveguides ( e.g., a bent strip or a twisted tube ) often has a point - like eigenvalue below the essential spectrum that corresponds to a trapped eigenmode of finite l2 norm.   we revisit this statement for resonators with long but finite branches that we call `` finite waveguides ''.   although now there is no essential spectrum and all eigenfunctions have finite l2 norm, the trapping can be understood as an exponential decay of the eigenfunction inside the branches.   we describe a general variational formalism for detecting trapped modes in such resonators. for finite waveguides with general cylindrical branches,   we obtain a sufficient condition which determines the minimal length of branches for getting a trapped eigenmode.   varying the branch lengths may switch certain eigenmodes from non - trapped to trapped states.   these concepts are illustrated for several typical waveguides ( l - shape, bent strip, crossing of two stripes, etc. ).   we conclude that the well - established theory of trapping in infinite waveguides may be incomplete and require further development for being applied to microscopic quantum devices.   _ keywords _ : eigenfunction, laplace operator, trapping, localization, decay, resonator
description of nonclassicality of states has hitherto been through violation of bell inequality and non - separability, with the latter being a stronger constraint. in this paper, we show that this can be further sharpened, by introducing the concept of classical simulation.   a state admits classical simulation if it can be mimicked fully by a separable state of higher dimension. a nonclassical state, which we call exceptional, does not admit classical simulation.   focusing on two qubit states, we show that exceptionality is more stringent than violation of bell inequality, and involves an intricate interplay of coherence and entanglement.   the new criterion is shown to provide a natural description of entangled states which respect bell inequality, and also a way of enumerating the classical resources that are required to simulate a quantum state.   possible implications to quantum dynamics and quantum information are briefly touched upon.
the ever  expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age  composition parameter space that are largely unexplored at present.   stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations.   the dartmouth stellar evolution database is a collection of stellar evolution tracks and isochrones that spans a range of @xmath0}}$ ] from 2.5 to + 0.5, @xmath1}}$ ] from 0.2 to + 0.8 ( for @xmath0}}\leq$]0 ) or + 0.2 ( for @xmath0}}>$]0 ), and initial he mass fractions from y=0.245 to 0.40.   stellar evolution tracks were computed for masses between 0.1 and 4 @xmath2 allowing isochrones to be generated for ages as young as 250 myr. for the range in masses   where the core he flash occurs, separate he - burning tracks were computed starting from the zero age horizontal branch. the tracks and isochrones   have been transformed to the observational plane in a variety of photometric systems including standard ubv(ri)@xmath3, strmgren uvby, the sloan digital sky survey ugriz, the two micron all sky survey jh@xmath4, and hubble space telescope acs - wfc and wfpc2.   the dartmouth stellar evolution database is accessible through a websitemodels/ ] where all tracks, isochrones, and additional files can be downloaded.
electrical transport properties as a function of magnetic field and time have been investigated in polycrystalline, nd@xmath0sr@xmath1coo@xmath2. a strong exchange bias ( eb ) effect   is observed associated with the fairly large intragranular magnetoresistance ( mr ).   the eb effect observed in the mr curve is compared with the eb effect manifested in magnetic hysteresis loop.   training effect, described as the decrease of eb effect when the sample is successively field - cycled at a particular temperature, has been observed in the shift of the mr curve.   training effect could be analysed by the successful models.   the eb effect, mr and a considerable time dependence in mr are attributed to the intrinsic nanostructure giving rise to the varieties of magnetic interfaces in the grain interior.
partonic cross sections for the production of massive objects in hadronic collisions receive large corrections when the invariant mass of the initial - state partons is just above the production threshold.   since typically the center - of - mass energy of the hadronic collision is much higher than the mass of the heavy objects, it is not obvious that these contributions translate into large corrections to the hadronic cross section. using a recent approach to threshold resummation based on effective field theory  , we quantify to which extent the fall - off of the parton densities at high @xmath0 leads to a dynamical enhancement of the partonic threshold region.   with the example of drell - yan production, we study the emergence of an effective physical scale characterizing the soft emissions in the process.   we derive compact analytical expressions for the resummed drell - yan cross section and rapidity distribution directly in momentum space.   they are free of landau - pole singularities and are trivially matched onto fixed - order perturbative calculations. evaluating the resummed cross sections at nnnll order and matching onto nnlo fixed - order calculations, we perform a detailed numerical analysis of the cross section and rapidity distribution in @xmath1 collisions.   clns  07/2009 + fermilab - pub-07 - 507-t + mz - th/07 - 16 + october 2, 2007    * dynamical threshold enhancement and resummation in drell - yan production *    thomas becher@xmath2, matthias neubert@xmath3 and gang xu@xmath4 +
= 0.6 cm    * abstract *    we study the absorption probability and hawking radiation of the scalar field in the rotating gdel black hole in minimal five - dimensional gauged supergravity.   we find that gdel parameter @xmath0 imprints in the greybody factor and hawking radiation.   it plays a different role from the angular momentum of the black hole in the hawking radiation and super - radiance.   these information can help us know more about rotating gdel black holes in minimal five - dimensional gauged supergravity.   = 0.8 cm
magnetic impurities affect the spectrum of excitations of a superconductor and thus influence its impedance.   we concentrate on the dissipative part of the surface impedance.   we investigate its dependence on frequency, the density and strength of magnetic impurities, and the density and temperature of quasiparticles.   even a small concentration of weak magnetic impurities significantly modifies the excitation spectrum in the vicinity of the bcs gap.   therefore, we give special attention to the absorption threshold behavior at zero temperature and to the low - frequency absorption by quasiparticles.   the discrete energy states introduced at low density of magnetic impurities may serve as traps for nonequilibrium quasiparticles, reducing the absorption in some range of low radiation frequencies.
we perform a model independent reconstruction of the cosmic expansion rate based on type ia supernova data. using the union 2.1 data set,   we show that the _ hubble _ parameter behaviour allowed by the data without making any hypothesis about cosmological model or underlying gravity theory is consistent with a flat @xmath0cdm universe having @xmath1 and * @xmath2, * weakly dependent on the choice of initial scatter matrix.   this is in closer agreement with the recently released planck results ( @xmath3 ) than other standard analyses based on type ia supernova data.   we argue this might be an indication that, in order to tackle subtle deviations from the standard cosmological model present in type ia supernova data, it is mandatory to go beyond parametrized approaches.       supernovae : general  cosmology : cosmological parameters  cosmology : observations  cosmology : theory
relativistic jets associated with long / soft gamma - ray bursts are formed and initially propagate in the interior of the progenitor star.   because of the subsequent loss of their external pressure support after they cross the stellar surface, these flows can be modeled as moving around a corner. a strong steady - state rarefaction wave is formed, and the sideways expansion is accompanied by a _ rarefaction acceleration_. we investigate the efficiency and the general characteristics of this mechanism by integrating the steady - state, special relativistic, magnetohydrodynamic equations, using a special set of partial exact solutions in planar geometry ( @xmath0 self - similar with respect to the `` corner '' ).   we also derive analytical approximate scalings in the ultrarelativistic cold / magnetized, and hydrodynamic limits.   the mechanism is more effective in magnetized than in purely hydrodynamic flows.   it substantially increases the lorentz factor without much affecting the opening of the jet ; the resulting values of their product can be much grater than unity, allowing for possible breaks in the afterglow light curves.   these findings are similar to the ones from numerical simulations of axisymmetric jets by komissarov et al and tchekhovskoy et al, although in our approach we describe the rarefaction as a steady - state simple wave and self - consistently calculate the opening of the jet that corresponds to zero external pressure.       gamma - ray burst : general  mhd  methods : analytical  relativistic processes
tunneling of electrons through rotor - stator anthracene aldehyde molecular interfaces is studied with a combined _ ab initio _ and model approach.   molecular electronic structure calculated from first principles is utilized to model different shapes of tunneling barriers.   together with a rectangular barrier, we also consider a sinusoidal shape that captures the effects of the molecular internal structure more realistically.   quasiclassical approach with the simmons formula for current density is implemented.   special attention is paid on conformational dependence of the tunneling current.   our results confirm that the presence of the side aldehyde group enhances the interesting electronic properties of the pure anthracene molecule, making it a bistable system with geometry dependent transport properties.   we also investigate the transition voltage and we show that confirmation dependent field emission could be observed in these molecular interfaces at realistically low voltages.   the present study accompanies our previous work where we investigated the coherent transport via strongly coupled delocalized orbital by application of non - equilibrium green s function formalism.
we analyze a complex scalar field with @xmath0 interaction and a chemical potential @xmath1 on the lattice.   an exact flux representation of the partition sum is used which avoids the complex action problem and based on a generalized worm algorithm we can run monte carlo simulations at arbitrary densities.   we study thermodynamical quantities as a function of the chemical potential @xmath1 for zero- and finite temperature.   it is shown that at zero temperature thermodynamical observables are independent of @xmath1 up to a critical value @xmath2 ( silver blaze phenomenon ). in a spectroscopy calculation we cross - check that @xmath3 agrees with the mass @xmath4 of the scalar field.   the silver blaze region ends in a second order phase transition and we show that for low temperatures the second order phase boundary persists and separates a pseudo silver blaze region from a condensed phase with strong @xmath1-dependence  .    @xmath5 int - pub-12 - 030     lattice study of the silver blaze phenomenon for a charged scalar @xmath0 field christof gattringer@xmath6, thomas kloiber@xmath7 @xmath8karl - franzens university graz + institute for physics + universittsplatz 5, a-8010 graz, austria @xmath9university of washington, seattle + institute for nuclear theory + box 351560, seattle, wa 98195, usa    _ nuclear physics b ( in print )   _    christof.gattringer@uni-graz.at + thomas.kloiber@gmx.at    0
the physics of exotic hadrons is revisited and reviewed, with emphasis on flavour configurations which have not yet been investigated.   the constituent quark model of multiquark states is discussed in some detail, as it can serve as a guide for more elaborate approaches.
this paper presents the analysis of axisymmetric helical magnetorotational instability ( hmri ) in the inviscid limit, which is relevant for astrophysical conditions.   the inductionless approximation defined by zero magnetic prandtl number is adopted to distinguish the hmri from the standard mri in the cylindrical taylor - couette flow subject to a helical magnetic field. using a chebyshev collocation method convective and absolute instability thresholds   are computed in terms of the elsasser number for a fixed ratio of inner and outer radii @xmath0 and various ratios of rotation rates and helicities of the magnetic field.   it is found that the extension of self - sustained hmri modes beyond the rayleigh limit does not reach the astrophysically relevant keplerian rotation profile not only in the narrow- but also in the finite - gap approximation.   the keppler limit can be attained only by the convective hmri mode provided that the boundaries are perfectly conducting.   however, this mode requires not only a permanent external excitation to be observable but also has a long axial wave length, which is not compatible with limited thickness of astrophysical accretion disks.
the 2009 run provided the first proton - proton collisions from the large hadron collider ( lhc ) at center of mass energies of 900 gev and 2.36 tev.   the compact muon solenoid ( cms ) experiment has recorded a large sample of minimum bias events from these collisions.   we present results from the all silicon tracking detectors from this run.   the performance of the tracker and track reconstruction algorithms are considered including signal - to - noise, efficiencies and comparisons to simulation for track parameter and resonance reconstruction performance.
in this study, we have investigated factors of determination which can affect the connected structure of a stock network.   the representative index for topological properties of a stock network is the number of links with other stocks.   we used the multi - factor model, extensively acknowledged in financial literature. in the multi - factor model, common factors act as independent variables while returns of individual stocks act as dependent variables.   we calculated the coefficient of determination, which represents the measurement value of the degree in which dependent variables are explained by independent variables.   therefore, we investigated the relationship between the number of links in the stock network and the coefficient of determination in the multi - factor model.   we used individual stocks traded on the market indices of korea, japan, canada, italy and the uk.   the results are as follows.   we found that the mean coefficient of determination of stocks with a large number of links have higher values than those with a small number of links with other stocks.   these results suggest that common factors are significantly deterministic factors to be taken into account when making a stock network.   furthermore, stocks with a large number of links to other stocks can be more affected by common factors.
we use the two - degree field galaxy redshift survey ( 2dfgrs ) to test the hierarchical scaling hypothesis : namely, that the @xmath0-point galaxy correlation functions can be written in terms of the two point correlation function or variance.   this scaling is expected if an initially gaussian distribution of density fluctuations evolves under the action of gravitational instability.   we measure the volume averaged @xmath0-point correlation functions using a counts in cells technique applied to a volume limited sample of 44,931 @xmath1 galaxies.   we demonstrate that @xmath2 galaxies display hierarchical clustering up to order @xmath3 in redshift space.   the variance measured for @xmath2 galaxies is in excellent agreement with the predictions from a @xmath4-cold dark matter n - body simulation.   this applies to all cell radii considered, @xmath5.   however, the higher order correlation functions of @xmath1 galaxies have a significantly smaller amplitude than is predicted for the dark matter for @xmath6mpc.   this disagreement implies that a non - linear bias exists between the dark matter and @xmath1 galaxies on these scales.   we also show that the presence of two rare, massive superclusters in the 2dfgrs has an impact on the higher - order clustering moments measured on large scales.   cosmology : observations, large - scale structure of universe
in 1985, beeman, tsu and thorpe established an almost linear relation between the raman transverse - optic ( to ) peak width @xmath0 and the spread in mean bond angle @xmath1 in _ a_-si.   this relation is often used to estimate the latter quantity in experiments. in the last decade  , there has been significant progress in the computer generation of sample networks of amorphous silicon. exploiting this progress  , this manuscript presents a more accurate determination of the relation between @xmath0 and @xmath1 using 1000-atom configurations. also investigated and quantified   are the relations between the to peak frequency and the ratio of the intensities of the transverse - acoustic ( ta ) and to peak, both as functions of @xmath1.   as @xmath1 decreases, the ta / to intensity ratio decreases and the to peak frequency increases.   these relations offer additional ways to obtain structural information on _   a_-si from raman measurements.
we develop a numerical method for pricing multidimensional vanilla options in the black - scholes framework. in low dimensions, we improve an adaptive integration algorithm proposed by two of the authors by introducing a new splitting strategy based on a geometrical criterion. in higher dimensions, this new algorithm is used as a control variate after a dimension reduction based on principal component analysis.   numerical tests are performed on the pricing of basket, put on minimum and digital options in dimensions up to ten.   option pricing, adaptive numerical integration, control variate    65c05, 65d30,91g60
x - ray ionized reflection occurs when a surface is irradiated with x - rays so intense that its ionization state is determined by the ionization parameter @xmath0, where @xmath1 is the incident flux and @xmath2 the gas density.   it occurs in accretion, onto compact objects including black holes in both active galaxies and stellar - mass binaries, and possibly in gamma - ray bursts.   computation of model reflection spectra is often time - consuming. here   we present the results from a comprehensive grid of models computed with our code, which has now been extended to include what we consider to be all energetically - important ionization states and transitions.   this grid is being made available as an ionized - reflection model, reflion, for xspec.       x - rays : general  accretion, accretion discs  galaxies : active  radiative transfer  line : formation
we study first structure formation in @xmath0-dominated universes using large cosmological @xmath1-body / sph simulations.   we consider a standard @xmath0cdm model and a @xmath0wdm model in which the mass of the dark matter particles is taken to be @xmath2 kev.   the linear power spectrum for the @xmath0wdm model has a characteristic cut - off at a wavenumber @xmath3 mpc@xmath4, suppressing the formation of low mass ( @xmath5 ) nonlinear objects early on.   the absence of low mass halos in the wdm model makes the formation of primordial gas clouds with molecular hydrogen very inefficient at high redshifts.   the first star - forming gas clouds form at @xmath6 in the wdm model, considerably later than in the cdm counterpart, and the abundance of these gas clouds differs by an order of magnitude between the two models.   we carry out radiative transfer calculations by embedding massive population iii stars in the gas clouds.   we show that the volume fraction of ionized gas rises up close to 100% by @xmath7 in the cdm case, whereas that of the wdm model remains extremely small at a level of a few percent.   thus the wdm model with @xmath2 kev is strongly inconsistent with the observed high optical depth by the _ wmap _ satellite.
the community structure of complex networks reveals both their organization and hidden relationships among their constituents.   most community detection methods currently available are not deterministic, and their results typically depend on the specific random seeds, initial conditions and tie - break rules adopted for their execution.   consensus clustering is used in data analysis to generate stable results out of a set of partitions delivered by stochastic methods. here   we show that consensus clustering can be combined with any existing method in a self - consistent way, enhancing considerably both the stability and the accuracy of the resulting partitions.   this framework is also particularly suitable to monitor the evolution of community structure in temporal networks.   an application of consensus clustering to a large citation network of physics papers demonstrates its capability to keep track of the birth, death and diversification of topics.
at zero temperature, in the chiral limit the amplitude for @xmath0 to decay into two photons is directly related to the coefficient of the axial anomaly. at any nonzero temperature, this direct relationship is lost : while the coefficient of the axial anomaly is independent of temperature, in a thermal bath the anomalous ward identities do not uniquely constrain the amplitude for @xmath1.   explicit calculation shows that to lowest order about zero temperature, this amplitude decreases.
in this paper, we propose a novel word - alignment - based method to solve the faq - based question answering task.   first, we employ a neural network model to calculate question similarity, where the word alignment between two questions is used for extracting features.   second, we design a bootstrap - based feature extraction method to extract a small set of effective lexical features.   third, we propose a learning - to - rank algorithm to train parameters more suitable for the ranking tasks.   experimental results, conducted on three languages ( english, spanish and japanese ), demonstrate that the question similarity model is more effective than baseline systems, the sparse features bring 5% improvements on top-1 accuracy, and the learning - to - rank algorithm works significantly better than the traditional method.   we further evaluate our method on the answer sentence selection task.   our method outperforms all the previous systems on the standard trec data set.
we present a time - dependent spectral model of the nebula 3c  58 and compare it with available data.   the model is for a leptonic nebula, in which particles are subject to synchrotron, inverse compton, self - synchrotron compton, adiabatic, and bremsstrahlung processes.   we find that 3c  58 is compatible with being a particle dominated nebula, with a magnetic field of 35@xmath0 g.   a broken power law injection fits well the multi - frequency data, with a break energy at about 40  gev.   we find that 3c  58 is not expected to appear in veritas or magic  ii, unless the local ir background is a factor of @xmath1 off galactic models averages. for cases in which the cmb dominates the inverse compton contribution, we find that 3c  58 will not be visible either for the cherenkov telescope array.
with monte carlo simulations, we investigate short - time critical dynamics of the three - dimensional anti - ferromagnetic ising model with a globally conserved magnetization @xmath0 ( not the order parameter ). from the power law behavior of the staggered magnetization ( the order parameter ), its second moment and the auto - correlation, we determine all static and dynamic critical exponents as well as the critical temperature.   the universality class of @xmath1 is the same as that without a conserved quantity, but the universality class of non - zero @xmath0 is different.    epsf.sty
we report the first detection of an ly@xmath0 absorption line associated with an overdense region in the intergalactic medium ( igm ) along the sightline towards pks  2155 - 304 with the _ chandra _ low energy transmission grating spectrometer ( letgs ).   the absorption line is detected at @xmath1 level with @xmath2. at the same velocity   @xcite detected a small group of spiral galaxies ( with an overdensity of @xmath3 ) and low metallicity ly@xmath0 clouds.   we constrain the intragroup gas that gives rise to the ly@xmath0 line to a baryon density in the range @xmath4 ( @xmath5 ) and a temperature of @xmath6 k, assuming 0.1 solar abundance.   these estimates are in accordance with those of the warm / hot intergalactic medium ( whim ) that are predicted from hydrodynamic simulations.   extrapolating from this single detection implies a large fraction of the `` missing baryons '' ( @xmath7 10%, or @xmath7 30 - 40% of the whim ) are probed by the absorber.
there is a broad need in the neuroscience community to understand and visualize large - scale recordings of neural activity, big data acquired by tens or hundreds of electrodes simultaneously recording dynamic brain activity over minutes to hours.   such dynamic datasets are characterized by coherent patterns across both space and time, yet existing computational methods are typically restricted to analysis either in space or in time separately. here   we report the adaptation of dynamic mode decomposition ( dmd ), an algorithm originally developed for the study of fluid physics, to large - scale neuronal recordings.   dmd is a modal decomposition algorithm that describes high - dimensional dynamic data using coupled spatial - temporal modes ; the resulting analysis combines key features of performing principal components analysis ( pca ) in space and power spectral analysis in time.   the algorithm scales easily to very large numbers of simultaneously acquired measurements.   we validated the dmd approach on sub - dural electrode array recordings from human subjects performing a known motor activation task.   next, we leveraged dmd in combination with machine learning to develop a novel method to extract sleep spindle networks from the same subjects.   we suggest that dmd is generally applicable as a powerful method in the analysis and understanding of large - scale recordings of neural activity.
object localization is an important computer vision problem with a variety of applications.   the lack of large scale object - level annotations and the relative abundance of image - level labels makes a compelling case for weak supervision in the object localization task.   deep convolutional neural networks are a class of state - of - the - art methods for the related problem of object recognition. in this paper, we describe a novel object localization algorithm which uses classification networks trained on only image labels.   this weakly supervised method leverages local spatial and semantic patterns captured in the convolutional layers of classification networks.   we propose an efficient beam search based approach to detect and localize multiple objects in images.   the proposed method significantly outperforms the state - of - the - art in standard object localization data - sets with a 8 point increase in map scores.
very soon the lhc will provide beams for heavy ion collisions at 5.52 tev / nucleon.   this center - of - mass energy results in a large cross - section for producing high-@xmath0 ( @xmath1 50 gev ) jets that are distinct from the soft, underlying event.   this brings with it the possibility of performing full jet reconstruction to directly study jet energy loss in the medium produced in heavy ion collisions. in this note, we present the current state of jet reconstruction performance studies in heavy ion events using the atlas detector.   we also discuss the possibilities of energy loss measurements available with full jet reconstruction : single jet @xmath2 and di - jet and @xmath3-jet correlations.
the problem of estimating the delays and amplitudes of a positive stream of pulses appears in many applications, such as single - molecule microscopy.   this paper suggests estimating the delays and amplitudes using a convex program, which is robust in the presence of noise ( or model mismatch ). particularly, the recovery error is proportional to the noise level.   we further show that the error grows exponentially with the density of the delays and also depends on the localization properties of the pulse.   stream of pulses ; sparse deconvolution ; convex optimization ; rayleigh regularity ; dual certificate ; super - resolution
we consider the coherent exciton transport, modeled by continuous - time quantum walks, on erds - rny graphs in the presence of a random distribution of traps. the role of trap concentration and of the substrate dilution is deepened showing that, at long times and for intermediate degree of dilution, the survival probability typically decays exponentially with a ( average ) decay rate which depends non monotonically on the graph connectivity ; when the degree of dilution is either very low or very high, stationary states, not affected by traps, get more likely giving rise to a survival probability decaying to a finite value.   both these features constitute a qualitative difference with respect to the behavior found for classical walks.   quantum walks, trapping, random graphs
we analyze a composite broad - band optical / uv / x@xmath0-ray spectrum of the seyfert 1 galaxy ngc 5548.   the spectrum consists of an average of simultaneous optical/_iue_/_ginga _ observations accompanied by _   rosat _ and _ gro_/osse data from non - simultaneous observations.   we show that the broad - band continuum is inconsistent with simple disk models extending to the soft x - rays. instead  , the soft - excess is well described by optically thick, low temperature, thermal comptonization which may dominate the entire big blue bump.   this might explain the observed tight uv / soft x - ray variability correlation and absence of a lyman edge in this object.   however, the plasma parameters inferred by the spectrum need stratification in optical depth and/or temperature to prevent physical inconsistency.   the optical / uv / soft x - ray component contributes about half of the total source flux.   the spectral variations of the soft - excess are consistent with that of the uv and argue that the components are closely related.   the overall pattern of spectral variability suggests variations of the source geometry, and shows the optical / uv / soft x - ray component to be harder when brighter, while the hard x - ray component is softer when brighter.
the intermediate state dependence of photoelectron circular dichroism ( pecd ) in resonance - enhanced multi - photon ionization of fenchone in the gas phase is experimentally studied. by scanning the excitation wavelength from 359 to 431 nm   we simultaneously excite up to three electronically distinct resonances. in the pecd experiment performed with a broadband femtosecond laser their respective contributions to the photoelectron spectrum can be resolved.   high - resolution spectroscopy allows us to identify two of the resonances as belonging to the b- and c - bands, which involve excitation to states with 3s and 3p rydberg character, respectively.   we observe a sign change in the pecd signal depending on which electronic state is used as an intermediate.   additionally, scanning the laser wavelength reveals a decrease of pecd magnitude with increasing photoelectron energy for the 3s state.
the cosmic stellar birth rate can be measured by standard astronomical techniques.   it can also be probed via the cosmic stellar death rate, though until recently, this was much less precise.   however, recent results based on measured supernova rates, and importantly, also on the attendant diffuse fluxes of neutrinos and gamma rays, have become competitive, and a concordant history of stellar birth and death is emerging. the neutrino flux from all past core - collapse supernovae,   while faint, is realistically within reach of detection in super - kamiokande, and a useful limit has already been set.   i will discuss predictions for this flux, the prospects for neutrino detection, the implications for understanding core - collapse supernovae, and a new limit on the contribution of type - ia supernovae to the diffuse gamma - ray background.   cosmic star formation rate, supernovae, neutrino background, gamma - ray background 97.60.bw, 98.70.vc
we present observations of 86 post - asymptotic giant branch ( post - agb ) stars of oh maser transitions, taken with the parkes telescope between september 2002 and august 2003.   post - agb stars are the precursors of planetary nebulae, which have a wide range of morphologies that are not well explained. by studying the circumstellar envelopes of post - agb stars through the masers produced in them  , we hope to shed light on the origin of planetary nebula morphologies.
the quantum numbers and mass hierarchy of the glueballs observed in @xmath0-dimensional lattice qcd with gauge group su(@xmath1 ) are shown to be in agreement with a constituent picture.   the agreement is maintained when going from glueballs to gluelumps, and when the gauge group so(@xmath2 ) is taken instead of su(@xmath1 ).
the equilibrium properties of block copolymer micelles confined in polymer thin films are investigated using self - consistent field theory.   the theory is based on a model system consisting of ab diblock copolymers and a homopolymers.   two different methods, based on the radius of gyration tensor and the spherical harmonics expansion, are used to characterize the micellar shape.   the results reveal that the morphology of micelles in thin films depends on the thickness of the thin films and the selectivity of the confining surfaces. for spherical ( cylindrical ) micelles, the spherical ( cylindrical ) symmetry is broken by the presence of the one - dimensional confinement, whereas the top - down symmetry is broken by the selectivity of the confining surfaces.   morphological transitions from spherical or cylindrical micelles to cylinders or lamella are predicted when the film thickness approaches the micellar size.
detection of radiation signals is at the heart of precision metrology and sensing. in this article   we show how the fluctuations in photon counting signals can be exploited to optimally extract information about the physical parameters that govern the dynamics of the emitter. for a simple two - level emitter subject to photon counting,   we show that the fisher information and the cramr - rao sensitivity bound based on the full detection record can be evaluated from the waiting time distribution in the fluorescence signal which can, in turn, be calculated for both perfect and imperfect detectors by a quantum trajectory analysis.   we provide an optimal estimator achieving that bound.
we report the successful fabrication of lateral organic spin valves with a channel length in the sub @xmath0 regime. the fabication process is based on in - situ shadow evaporation under uhv conditions and therefore yields clean and oxygen - free interfaces between the ferromagnetic metallic electrodes and the organic semiconductor.   the spin valve devices consist of nickel and cobalt - iron electrodes and the high mobility _   n_-type organic semiconductor @xmath1-bis(heptafluorobutyl)-@xmath2-perylene diimide.   our studies comprise fundamental investigations of the process and materials suitability for the fabrication of lateral spin valve devices as well as magnetotransport measurements at room temperature.   the best devices exhibit a magnetoresistance of up to @xmath3, the largest value for room temperature reported so far.
for pure symmetric 3-qubit states there are only three algebraically independent entanglement measures ; one choice is the pairwise concurrence @xmath0, the 3-tangle @xmath1, and the kempe invariant @xmath2. using a canonical form for symmetric @xmath3-qubit states derived from their majorana representation, we derive the explicit achievable region of triples @xmath4.
we present mid - ir observations of the prototypical seyfert 2 galaxy ngc1068 obtained with isocam between 5 and 16@xmath0 m.   the proximity of this galaxy coupled with the spectro - imaging capabilities of the instrument allow us to separate the mid - ir emission of the active galactic nucleus ( agn ) from the distinctly different emission of the circumnuclear star forming regions.   the unidentified infrared bands ( uibs ), which trace the starburst contribution very well, are not detected in the spectrum of the agn region where their carriers could be destroyed.   moreover, the featureless continuum of the agn exhibits a strong hot dust component below 10@xmath0 m not observed in the starburst regions.   those two distinct mid - ir spectral properties, as well as the presence of high excitation ionic lines such as (7.7@xmath0 m ) and (14.3@xmath0 m ) in the agn spectrum, provide us with very powerful complementary tools to disentangle agns from starbursts.   the effects of high extinction on the mid - ir identification of agns are also discussed.
we explore a long josephson contact transporting cooper pairs between 1d charge - neutral chiral majorana modes in the leads via charged dirac chiral modes in the normal region.   we investigate the regimes of ( i ) transparent contacts and ( ii ) tunnel junctions implemented in 3d topological insulator / superconductor / magnet hybrid structures.   the setup acts as a squid controlled by the magnetic flux enclosed by the chiral loop of the normal region.   this chirality leads to the fractional @xmath0-periodic pattern of critical current.   the current - phase relation can have sawtooth - like shape with spikes at unusual even phases of @xmath1.
the effect of dephasing on electron transport through a benzene molecule is carefully examined using a phenomenological model introduced by bttiker. within a tight - binding framework   all the calculations are performed based on the green s function formalism.   we investigate the influence of dephasing on transmission probability and current - voltage characteristics for three different configurations ( _ ortho _, _ meta _ and _ para _ ) of the molecular system depending on the locations of two contacting leads.   the presence of dephasing provides a significant change in the spectral properties of the molecule and exhibits several interesting patterns that have so far remain unexplored.
we consider the phenomenology of @xmath0 violation in a color - octet extended scalar sector for @xmath1 production and decay at the lhc.   in particular we study the effect of the two neutral color - octet scalars @xmath2 and @xmath3 that occur in the model.   there are two new sources of @xmath0 violation : a phase in the couplings of @xmath4 to top - quarks ; and two phases in the quartic couplings of the scalar potential. in resonant production of a single @xmath4 followed by its decay into @xmath5 pairs through the parton level process   @xmath6, we find large raw @xmath0 asymmetries which can reach 12%.   these raw asymmetries are, of course, diluted by standard model ( sm ) @xmath1 pairs making observation of @xmath0 violation contingent on whether the resonance itself can be extracted from the sm background.
i report on recent measurements of two scaling relations of spheroids in the distant universe : the fundamental plane, and the relation between lensing velocity dispersion and stellar velocity dispersion.   the joint analysis of the two scaling relations indicates that the most massive ( above @xmath0 ) spheroids are consistent with no evolution since @xmath1 both in terms of star formation and internal structure.   furthermore their total mass density profile is on average well described by an isothermal sphere with no evidence for redshift evolution. at smaller masses   the picture appears to be substantially different, as indicated by evidence for substantial recent star formation ( as much as 20 - 40% of stellar mass formed since @xmath1 ), and by hints of a reduced dark matter content at smaller masses. a larger sample of lenses extending to velocity dispersions below 200kms@xmath2, and to redshifts above @xmath3   is needed to verify these trends.
a stochastic theory for the toppling activity in sandpile models is developed, based on a simple mean - field assumption about the toppling process.   the theory describes the process as an anti - persistent gaussian walk, where the diffusion coefficient is proportional to the activity.   it is formulated as a generalization of the it stochastic differential equation with an anti - persistent fractional gaussian noise source.   an essential element of the theory is re - scaling to obtain a proper thermodynamic limit, and it captures all temporal features of the toppling process obtained by numerical simulation of the bak - tang - wiesenfeld sandpile in this limit.
we evaluate pionic decay widths of @xmath0 hypernuclei using a shell model for, both the nuclear bound and the continuum nucleon wave functions in the final state, and distorted waves for the outgoing pion. an excellent agreement with the recent kek measurement of @xmath1-decay widths of @xmath2 and @xmath3 is found. besides, results for @xmath4 are consistent with the existing upper bound.    _   pacs : 21.80+a, 23.90.+w, 25.80.pw,13.30.-a, 23.20.js, 21.60.cs_ + _ keywords : @xmath0 hypernuclei, weak decay, mesonic decay, continuum shell model _.   -30pt    plus 2 mm minus 2 mm 23.0 cm -7.4 mm 2.6 mm    * pionic decay of @xmath0 hypernuclei in a continuum shell model *     + departamento de fsica moderna, universidad de granada, e-18071 granada, spain.
optical and ultraviolet observations of the type iin supernova 1995n at epochs between 321 and 1799 days after the explosion show three distinct velocity components.   the narrow lines come from circumstellar gas and show both low and high ionization.   this component has a low filling factor, and is photoionized by x - rays from the shock.   the intermediate component, which is dominated by newly processed oxygen, originates in a shell with velocity of 25005000 @xmath0, and most likely comes from the ejecta.   the hydrogen- and helium - dominated gas has a low ionization, a high density, and velocities that extend out to @xmath1.   strong signatures of ly@xmath2-pumped fluorescence lines of fe  ii are seen in the near - infrared and ultraviolet.   the he / h ratio, @xmath3 by number, and the nitrogen overabundance provide strong evidence for cno burning products.   the fluxes of the broad hydrogen and helium lines decrease considerably faster than the oxygen lines.   the h@xmath2 line profile shows strong evolution, with the red wing decreasing faster than the blue.   possible scenarios, involving either a clumpy circumstellar medium, or an aspherical distribution of the surrounding gas, are discussed based on the line profiles and physical conditions.   finally, we propose that type iin supernovae have their origin in red supergiants in a superwind phase.
lattice networks with dissipative interactions are often employed to analyze materials with discrete micro- or meso - structures, or for a description of heterogeneous materials which can be modelled discretely.   they are, however, computationally prohibitive for engineering - scale applications.   the ( variational ) quasicontinuum  ( qc ) method is a concurrent multiscale approach that reduces their computational cost by fully resolving the ( dissipative ) lattice network in small regions of interest while coarsening elsewhere.   when applied to damageable lattices, moving crack tips can be captured by adaptive mesh refinement schemes, whereas fully - resolved trails in crack wakes can be removed by mesh coarsening. in order to address   crack propagation efficiently and accurately, we provide in this contribution an adaptive meshing scheme for the variational qc method. to deal with coarsening  , we adopt enrichment functions and the partition of unity concept. for the description of crack geometries,   the signed distance function is used.   furthermore, necessary changes in the summation rule are presented. finally, as our standpoint is variational, we discuss implications of the mesh refinement and coarsening from an energy - consistency point of view.   all theoretical considerations are demonstrated using two numerical examples for which the resulting reaction forces, energy evolutions, and crack paths are compared to those of the direct numerical simulations.   lattice networks, quasicontinuum method, damage, extended finite element method, adaptivity, multiscale modelling, variational formulation
this paper develops a scattering theory to examine how point impurities affect transport through quantum wires.   while some of our new results apply specifically to hard - walled wires, others  for example, an effective optical theorem for two - dimensional waveguides  are more general.   we apply the method of images to the hard - walled guide, explicitly showing how scattering from an impurity affects the wire s conductance.   we express the effective cross section of a confined scatterer entirely in terms of the empty waveguide s green s function, suggesting a way in which to use semiclassical methods to understand transport properties of smooth wires.   in addition to predicting some new phenomena, our approach provides a simple physical picture for previously observed effects such as conductance dips and confinement - induced resonances.
zipf s law seems to be ubiquitous in human languages and appears to be a universal property of complex communicating systems. following the early proposal made by zipf concerning the presence of a tension between the efforts of speaker and hearer in a communication system, we introduce evolution by means of a variational approach to the problem based on kullback s minimum discrimination of information principle.   therefore, using a formalism fully embedded in the framework of information theory, we demonstrate that zipf s law is the only expected outcome of an evolving, communicative system under a rigorous definition of the communicative tension described by zipf.
the hundreds of exoplanets that have been discovered in the past two decades offer a new perspective on planetary structure. instead of being the archetypal examples of planets, those of our solar system are merely possible outcomes of planetary system formation and evolution, and conceivably not even terribly common outcomes (   although this remains an open question ).   here, we review the diverse range of interior structures that are known to, and speculated to, exist in exoplanetary systems  from mostly degenerate objects that are more than 10 times as massive as jupiter, to intermediate - mass neptune - like objects with large cores and moderate hydrogen / helium envelopes, to rocky objects with roughly the mass of the earth.
wolf - rayet hii galaxies are local metal - poor star - forming galaxies, observed when the most massive stars are evolving from o stars to wr stars, making them template systems to study distant starbursts.   we have been performing a program to investigate the interplay between massive stars and gas in wr hii galaxies using ifs. here, we highlight some results from the first 3d spectroscopic study of mrk  178, _ the closest metal - poor wr hii galaxy _, focusing on the origin of the nebular heii emission and the aperture effects on the detection of wr features.
we investigate the quantum entanglement dynamics of undriven anharmonic ( nonlinear ) oscillators with quartic potentials.   we first consider the indirect interaction between two such nonlinear oscillators mediated by a third, linear oscillator and show that it leads to a time - varying entanglement of the oscillators, the entanglement being strongly influenced by the nonlinear oscillator dynamics. in the presence of dissipation, the role of nonlinearity is strongly manifested in the steady state dynamics of the indirectly coupled anharmonic oscillators.   we further illustrate the effect of nonlinearities by studying the coupling between an electromagnetic field in a cavity with one movable mirror which is modeled as a nonlinear oscillator. for this case   we present a full analytical treatment, which is valid in a regime where both the nonlinearity and the coupling due to radiation pressure is weak.   we show that, without the need of any conditional measurements on the cavity field, the state of the movable mirror is non - classical as a result of the combined effect of the intrinsic nonlinearity and the radiation pressure coupling.   this interaction is also shown to be responsible for squeezing the movable mirror s position quadrature beyond the minimum uncertainty state even when the mirror is initially prepared in its ground state.
we present measurements of the effective temperatures and surface gravities for a sample of hot da white dwarfs, using the lyman line data available from the _ hut _, _ orfeus _  and _ fuse _  far - uv space missions. comparing the results with those from the standard balmer line technique, we find that there is a general good overall agreement between the two methods  . however, significant differences are found for a number of stars, but not always of a consistent nature in that sometimes the balmer temperature exceeds that derived from the lyman lines and in other instances is lower.   we conclude that, with the latest model atmosphere calculations, these discrepancies probably do not arise from an inadequate theoretical treatment of the lyman lines but rather from systematic effects in the observation and data reduction processes, which dominate the statistical errors in these spectra  . if these systematic data reduction effects can be adequately controlled, the lyman line temperature and gravity measurements are consistent with those obtained from the balmer lines when allowance is made for reasonable observational uncertainties.       stars : atmospheres  stars : white dwarfs  ultraviolet : stars.
synchronization transitions are investigated in coupled chaotic maps. depending on the relative weight of linear versus nonlinear instability mechanisms associated to the single map two different scenarios for the transition may occur.   when only two maps are considered we always find that the critical coupling @xmath0 for chaotic synchronization can be predicted within a linear analysis by the vanishing of the transverse lyapunov exponent @xmath1.   however, major differences between transitions driven by linear or nonlinear mechanisms are revealed by the dynamics of the transient toward the synchronized state. as a representative example of extended systems a one dimensional lattice of chaotic maps with power - law coupling   is considered. in this high dimensional model finite amplitude instabilities   may have a dramatic effect on the transition.   for strong nonlinearities an exponential divergence of the synchronization times with the chain length can be observed above @xmath0, notwithstanding the transverse dynamics is stable against infinitesimal perturbations at any instant.   therefore, the transition takes place at a coupling @xmath2 definitely larger than @xmath0 and its origin is intrinsically nonlinear.   the linearly driven transitions are continuous and can be described in terms of mean field results for non - equilibrium phase transitions with long range interactions. while the transitions dominated by nonlinear mechanisms appear to be discontinuous.   +    1.5 cm    synchronization ; coupled chaotic systems ; linear and nonlinear instabilities ; coupled map lattices 05.45.-a, 05.45.xt, 05.45.ra
we present a new and accurate fortran code, the bi - spectra and non - gaussianity operator ( bingo ), for the efficient numerical computation of the scalar bi - spectrum and the non - gaussianity parameter @xmath0 in single field inflationary models involving the canonical scalar field.   the code can calculate all the different contributions to the bi - spectrum and the parameter @xmath0 for an arbitrary triangular configuration of the wavevectors. focusing firstly on the equilateral limit  , we illustrate the accuracy of bingo by comparing the results from the code with the spectral dependence of the bi - spectrum expected in power law inflation.   then, considering an arbitrary triangular configuration, we contrast the numerical results with the analytical expression available in the slow roll limit, for, say, the case of the conventional quadratic potential. considering a non - trivial scenario involving deviations from slow roll  , we compare the results from the code with the analytical results that have recently been obtained in the case of the starobinsky model in the equilateral limit. as an immediate application  , we utilize bingo to examine of the power of the non - gaussianity parameter @xmath0 to discriminate between various inflationary models that admit departures from slow roll and lead to similar features in the scalar power spectrum.   we close with a summary and discussion on the implications of the results we obtain.
we give a method to construct cospectral graphs for the normalized laplacian by a local modification in some graphs with special structure.   namely, under some simple assumptions, we can replace a small bipartite graph with a cospectral mate without changing the spectrum of the entire graph.   we also consider a related result for swapping out biregular bipartite graphs for the matrix @xmath0.   we produce ( exponentially ) large families of non - bipartite, non - regular graphs which are mutually cospectral, and also give an example of a graph which is cospectral with its complement but is not self - complementary.   * keywords : *  normalized laplacian ; cospectral ; bipartite subgraph swapping
the stability and chaotic behaviors of bose - einstein condensates with two- and three - atom interactions in optical lattices are discussed with analytical and numerical methods.   it is found that the steady - state relative population appears tuning - fork bifurcation when the system parameters are changed to certain critical values. in particular, the existence of three - body interaction not only transforms the bifurcation point of the system but also affects greatly on the macroscopic quantum self - trapping behaviors of the system associated with the critically stable steady - state solution.   in addition, we also investigated the influence of the initial conditions, three - body interaction and the energy bias on the macroscopic quantum self - trapping.   finally, by applying the periodic modulation on the energy bias, we find that the relative population oscillation exhibits a process from order to chaos, via a series of period - doubling bifurcations.
this paper studies the cardinal interpolation operators associated with the general multiquadrics, @xmath0, @xmath1.   these operators take the form @xmath2 where @xmath3 is a fundamental function formed by integer translates of @xmath4 which satisfies the interpolatory condition @xmath5.   we consider recovery results for interpolation of bandlimited functions in higher dimensions by limiting the parameter @xmath6. in the univariate case  , we consider the norm of the operator @xmath7 acting on @xmath8 spaces as well as prove decay rates for @xmath3 using a detailed analysis of the derivatives of its fourier transform, @xmath9.
the systematic study of the correlation between the experimental giant dipole resonance ( gdr ) width and the average deformation @xmath0 of the nucleus at finite excitation is presented for the mass region a @xmath1 59 to 208.   we show that the width of the gdr ( @xmath2 ) and the quadrupole deformation of the nucleus do not follow a linear relation, as predicted earlier, due to the gdr induced quadrupole moment and the correlation also depends on the mass of the nuclei.   the different empirical values of @xmath0 extracted from the experimental gdr width match exceptionally well with the thermal shape fluctuation model. as a result  , this universal correlation between @xmath0 and @xmath2 provides a direct experimental probe to determine the nuclear deformation at finite temperature and angular momentum in the entire mass region.
we analyze the quantum entanglement between two interacting atoms trapped in a spherical harmonic potential. at ultra - cold temperature,   ground state entanglement is generated by the dominated s - wave interaction.   based on a regularized pseudo - potential hamiltonian, we examine the quantum entanglement by performing the schmidt decomposition of low - energy eigenfunctions.   we indicate how the atoms are paired and quantify the entanglement as a function of a modified s - wave scattering length inside the trap.
the feedback from galactic outflows is thought to play an important role in shaping the gas content, star formation history, and ultimately the stellar mass function of galaxies.   here we present evidence for massive molecular outflows associated with ultra - luminous infrared galaxies ( ulirgs ) in the coadded redshift search receiver @xmath0co ( 10 ) spectrum.   our stacked spectrum of 27 ulirgs at @xmath1 ( @xmath2ghz ) shows broad wings around the co line with @xmath3 2000  km  s@xmath4. its integrated line flux accounts for up to 25@xmath5% of the total co line luminosity.   when interpreted as a massive molecular outflow wind, the associated mechanical energy can be explained by a concentrated starburst with @xmath6 yr@xmath4, which agrees well with their @xmath7 derived from the @xmath8 luminosity. using the high signal - to - noise stacked composite spectrum  , we also probe @xmath9co and @xmath0cn emission in the sample and discuss how the chemical abundance of molecular gas may vary depending on the physical conditions of the nuclear region.
it is well known that amorphous solids display a phonon spectrum where the debye @xmath0 law at low frequency melds into an anomalous excess - mode peak ( the boson peak ) before entering a quasi - localized regime at higher frequencies dominated by scattering.   the microscopic origin of the boson peak has remained elusive despite various attempts to put it in a clear connection with structural disorder at the atomic / molecular level.   using numerical calculations on model systems, we show that the microscopic origin of the boson peak is directly controlled by the local breaking of center - inversion symmetry.   in particular, we find that both the boson peak and the nonaffine softening of the material display a strong positive correlation with a new order parameter describing the local inversion symmetry of the lattice.   the standard bond - orientational order parameter, instead, is shown to be a poor correlator and can not explain the boson peak in randomly - cut crystals with perfect bond - orientational order.   our results bring a unifying understanding of the boson peak anomaly for model glasses and defective crystals in terms of a universal local symmetry - breaking principle of the lattice.
we report the redshift of a distant, highly obscured submm galaxy ( smg ), based entirely on the detection of its co line emission. we have used the newly commissioned eight - mixer receiver ( emir ) at the iram 30 m telescope, with its 8ghz of instantaneous dual - polarization bandwidth, to search the 3-mm atmospheric window for co emission from smmj14009 + 0252, a bright smg detected in the scuba lens survey.   a detection of the co(32 ) line in the 3-mm window was confirmed via observations of co(54 ) in the 2-mm window.   both lines constrain the redshift of smmj14009 + 0252 to @xmath0, with high precision ( @xmath1 ).   such observations will become routine in determining redshifts in the era of the atacama large millimeter / submillimeter array ( alma ).
vortex penetration affects the stability of a superconducting system and limits the possible application of the system.   however, the mathematical description to this phenomenon is currently unavailable. here   i presented a mathematical model in which i considered the effects of bulk pinning and internal field repulsive force on vortex hopping.   thereafter, i proposed a series expansion to the activation energy and derived a general formula to describe the time dependence of the vortex penetration process. with these formulas,   i can analyze the experimental data and calculate the activation energy of the vortex penetration phenomenon.   the results are accurate for the time dependence of the internal field measurements in a @xmath0 superconductor.
we consider linear and nonlinear modes pinned to a grating - free ( gapless ) layer placed between two symmetric or asymmetric semi - infinite bragg gratings ( bgs ), with a possible phase shift between them, in a medium with the uniform kerr nonlinearity.   the asymmetry is defined by a difference between bandgap widths in the two bgs. in the linear system,   exact defect modes ( dms ) are found.   composite gap solitons pinned to the central layer are found too, in analytical and numerical forms, in the nonlinear model. in the asymmetric system,   existence boundaries for the dms and gap solitons, due to the competition between attraction to the gapless layer and repulsion from the reflectivity step, are obtained analytically.   stability boundaries for solitons in the asymmetric system are identified by means of direct simulations.   collisions of moving bg solitons with the gapless layer are studied too.
this paper studies interference alignment ( ia ) based multi - cell cooperative resource allocation for the downlink ofdma with universal frequency reuse. unlike the traditional scheme that treats subcarriers as separate dimensions for resource allocation, the ia technique is utilized to enable frequency - domain precoding over parallel subcarriers. in this paper, the joint optimization of frequency - domain precoding via ia, subcarrier user selection and power allocation   is investigated for a cooperative three - cell ofdma system to maximize the downlink throughput.   numerical results for a simplified symmetric channel setup reveal that the ia - based scheme achieves notable throughput gains over the traditional scheme only when the inter - cell interference link has a comparable strength as the direct link, and the receiver snr is sufficiently large. motivated by this observation, a practical hybrid scheme is proposed for cellular systems with heterogenous channel conditions, where the total spectrum is divided into two subbands, over which the ia - based scheme and the traditional scheme are applied for resource allocation to users located in the cell - intersection region and cell - non - intersection region, respectively.   it is shown that this hybrid resource allocation scheme flexibly exploits the downlink ia gains for ofdma - based cellular systems.
a technique using vector slepian harmonics and vector slepian multipole fields is presented for a general treatment of the inverse problem of high numerical aperture focusing.   a prescribed intensity distribution or electric field distribution in the focal volume is approximated using numerical optimization and the corresponding illuminating field at the entrance pupil is constructed.   three examples from the recent literature are chosen to illustrate the method.    high numerical aperture focusing, vector diffraction theory, inverse problem, slepian s concentration problem
we have developed an efficient simulation tool gollum for the computation of electrical, spin and thermal transport characteristics of complex nanostructures. the new multi - scale, multi - terminal tool addresses a number of new challenges and functionalities that have emerged in nanoscale - scale transport over the past few years. to illustrate the flexibility and functionality of gollum, we present a range of demonstrator calculations encompassing charge, spin and thermal transport, corrections to density functional theory such as lda+u and spectral adjustments, transport in the presence of non - collinear magnetism, the quantum - hall effect, kondo and coulomb blockade effects, finite - voltage transport, multi - terminal transport, quantum pumps, superconducting nanostructures, environmental effects and pulling curves and conductance histograms for mechanically - controlled - break - junction experiments.   = 1
in our previous paper, we evaluated the transit duration variation ( tdv ) effect for a co - aligned planet - moon system at an orbital inclination of @xmath0. here  , we will consider the effect for the more general case of @xmath1 and an exomoon inclined from the planet - star plane by euler rotation angles @xmath2 and @xmath3.   we find that the tdv signal has two major components, one due to the velocity variation effect described in our first paper and one new component due to transit impact parameter variation. by evaluating the dominant terms, we find the two effects are additive for prograde exomoon orbits, and deductive for retrograde orbits  . this asymmetry could allow for future determination of the orbital sense of motion.   we re - evaluate the ratio of tdv and ttv effects, @xmath4, in the more general case of an inclined planetary orbit with a circular orbiting moon and find that it is still possible to directly determine the moon s orbital separation from just the ratio of the two amplitudes, as first proposed in our previous paper.       techniques : photometric  planets and satellites : general  planetary systems  occultations  methods : analytical
the bright x - ray selected bl lac object 1es1101232 shows a flat x - ray spectrum, making it detectable with high statistics over the wide bepposax energy range.   we have observed it in two different epochs with bepposax, and found a variation of the flux of about 30% that can be explained by a change in the spectral index above the synchrotron peak.   we present here the data and infer limits on the strength of the magnetic field based on models of emission for high - frequency peaked bl lacs.
extreme ultraviolet images of the corona contain information over a large range of spatial scales, and different structures such as active regions, quiet sun and filament channels contain information at very different brightness regimes.   processing of these images is important to reveal information, often hidden within the data, without introducing artifacts or bias.   it is also important that any process be computationally efficient, particularly given the fine spatial and temporal resolution of _ atmospheric imaging assembly _ on the _ solar dynamics observatory _   ( aia / sdo ), and consideration of future higher - resolution observations.   a very efficient process is described here which is based on localized normalizing of the data at many different spatial scales.   the method reveals information at the finest scales, whilst maintaining enough of the larger - scale information to provide context.   it also intrinsically flattens noisy regions and can reveal structure in off - limb regions out to the edge of the field of view.   the method is also successfully applied to a white light coronagraph observation.
the hyperfine structure of @xmath0 states in @xmath1sr was studied for principal quantum numbers @xmath2 by doppler - free two - photon excitation combined with thermionic detection. based on the more accurate data, compared to previous results,   the hyperfine structure was analysed by second order perturbation theory using mqdt wavefunctions. as a result   we find that the surprisingly large @xmath3-factors obtained by fitting the data with the casimir formula do not reflect a quadrupolar interaction but rather consist predominantly of second order magnetic dipole contributions.   further, inconsistencies in the king plot of odd - even isotope shifts were removed by this type of analysis.   the result demonstrates the importance of higher order effects in hyperfine splittings of excited states in atoms with two valence electrons, even when the fine structure splitting is large compared to the hyperfine splitting.   pacs numbers : 35.10.fk, 32.80.rm, 31.30.gs
we consider a discrete - time random walk on the nodes of a graphene - like graph, i.e.  an unbounded hexagonal lattice.   we determine the probability generating functions, the transition probabilities and the relevant moments. the convergence of the stochastic process to a 2-dimensional brownian motion is also discussed.   finally, we obtain some results on its asymptotic behavior making use of large deviation theory.   _ keywords : _ random walk ; hexagonal lattice ; probability generating function ; large deviations ; moderate deviations.   _ maths subject classification : _ 60j15 ; 60f10 ; 82c41
we consider different properties of small open quantum systems coupled to an environment and described by a non - hermitian hamilton operator.   of special interest is the non - analytical behavior of the eigenvalues in the vicinity of singular points, the so - called exceptional points ( eps ), at which the eigenvalues of two states coalesce and the corresponding eigenfunctions are linearly dependent from one another.   the phases of the eigenfunctions are not rigid in approaching an ep and providing therewith the possibility to put information from the environment into the system.   all characteristic properties of non - hermitian quantum systems hold true not only for natural open quantum systems that suffer _ loss _ due to their embedding into the continuum of scattering wavefunctions.   they appear also in systems coupled to different layers some of which provide _ gain _ to the system.   thereby gain and loss, respectively, may be fixed inside every layer, i.e. characteristic of it.
we develop a theory of static bps domain walls in stringy landscape and present a large family of bps walls interpolating between different supersymmetric vacua.   examples include kklt models, stu models, type iib multiple flux vacua, and models with several minkowski and ads vacua.   after the uplifting, some of the vacua become ds, whereas some others remain ads.   the near - bps walls separating these vacua may be seen as bubble walls in the theory of vacuum decay. as an outcome of our investigation of the bps walls  , we found that the decay rate of ds vacua to a collapsing space with a negative vacuum energy can be quite large.   the parts of space that experience a decay to a collapsing space, or to a minkowski vacuum, never return back to ds space.   the channels of irreversible vacuum decay serve as sinks for the probability flow.   the existence of such sinks is a distinguishing feature of the landscape.   we show that it strongly affects the probability distributions in string cosmology.     + su - itp-2006 - 17 +   + may 29, 2006    _   @xmath0 infn @xmath1 dipartimento di fisica teorica + universita di torino, via pietro giuria 1, 10125 torino, italy _    _   @xmath2 physics department, theory unit, cern, + ch 1211, geneva 23, switzerland _    5.5 mm
the distance, star formation history and global properties of the local group dirr galaxy sagdig are derived based on an [ @xmath0 colour  magnitude diagram of @xmath1 stars.   a distance of @xmath2 mpc is obtained from the @xmath3 magnitude of the trgb.   this corresponds to 1.17 mpc to the barycenter of the local group and 1.34 to m 31, being ddo 210, at 0.35 mpc, the nearest galaxy to sagdig.   the metallicity is estimated from the colour of the rgb to be  @xmath4.   sagdig is hence a probable member of the local group and a candidate for the lowest - metallicity star forming galaxy known.   the radial density profile of the galaxy has been obtained together with other integrated properties ( magnitude, colour and central surface density ).   the galaxy density profile is fitted by an exponential law of scale length @xmath5, corresponding to 140 pc.   the star formation history of sagdig has been analysed, based on synthetic colour   magnitude diagrams.   the galaxy is currently in a high star formation activity epoch, forming stars at a rate about 10 times greater than the average for its entire life.   this is a common feature of galaxies classified as dirrs.
in analogy to iii - v compounds, which have significantly broadened the scope of group iv semiconductors, we propose iv - vi compounds as isoelectronic counterparts to layered group v semiconductors. using _   ab initio _ density functional theory, we study yet unrealized structural phases of silicon mono - sulfide ( sis ). we find the black - phosphorus - like @xmath0-sis to be almost equally stable as the blue - phosphorus - like @xmath1-sis. both @xmath0-sis and @xmath1-sis   monolayers display a significant, indirect band gap that depends sensitively on the in - layer strain.   unlike 2d semiconductors of group v elements with the corresponding nonplanar structure, different sis allotropes show a strong polarization either within or normal to the layers.   we find that sis may form both lateral and vertical heterostructures with phosphorene at a very small energy penalty, offering an unprecedented tunability in structural and electronic properties of sis - p compounds.
stationary and isotropic iteration stable random tessellations are considered, which can be constructed by a random process of cell division.   the collection of maximal polytopes at a fixed time @xmath0 within a convex window @xmath1 is regarded and formulas for mean values, variances, as well as a characterization of certain covariance measures are proved.   the focus is on the case @xmath2, which is different from the planar one, treated separately in @xcite.   moreover, a multivariate limit theorem for the vector of suitably rescaled intrinsic volumes is established, leading in each component  in sharp contrast to the situation in the plane  to a non - gaussian limit.   # 1    * key words : * central limit theory ; integral geometry ; intrinsic volumes ; iteration / nesting ; markov process ; martingale ; random tessellation ; stochastic stability ; stochastic geometry + * msc ( 2000 ) : * primary : 60d05 ; secondary : 52a22 ; 60f05
we have performed a complete one - loop calculation of @xmath0 in the standard model, including both gauge bosons and fermions in the loop.   we confirm the large irreducible continuum background from the @xmath1-boson loop found by jikia.   we have included the photon - photon luminosity, and find that the continuum background of transverse @xmath2 boson pairs prohibits finding a heavy higgs with mass @xmath3 gev in this decay mode.   = cmssbx10 scaled 2    the @xmath1 boson loop background to @xmath4 + at photon - photon colliders    physics department, university of wisconsin, madison, wi 53706, usa +
to demonstrate the feasibility of studying the epoch of massive galaxy cluster formation in a more systematic manner using current and future galaxy surveys, we report the discovery of a large sample of proto - cluster candidates in the 1.62 deg@xmath0 cosmos / ultravista field traced by optical / ir selected galaxies using photometric redshifts. by comparing properly smoothed 3d galaxy density maps of the observations and a set of matched simulations incorporating the dominant observational effects ( galaxy selection and photometric redshift uncertainties ),   we first confirm that the observed @xmath1 comoving mpc scale galaxy clustering is consistent with @xmath2cdm models. using further the relation between high - z overdensity and the present day cluster mass calibrated in these matched simulations, we found 36 candidate structures at @xmath3, showing overdensities consistent with the progenitors of m@xmath4 m@xmath5 clusters. taking into account the significant upward scattering of lower mass structures, the probabilities for the candidates to have at least m@xmath6 m@xmath5 are @xmath7. for each structure, about @xmath8 of photometric galaxy candidates are expected to be true proto - cluster members that will merge into a cluster - scale halo by @xmath9. with solely photometric redshifts,   we successfully rediscover two spectroscopically confirmed structures in this field, suggesting that our algorithm is robust.   this work generates a large sample of uniformly - selected proto - cluster candidates, providing rich targets for spectroscopic follow - up and subsequent studies of cluster formation.   meanwhile, it demonstrates the potential for probing early cluster formation with upcoming redshift surveys such as the hobby - eberly telescope dark energy experiment and the subaru prime focus spectrograph survey.
we present an analysis of the 2150kev spectrum of the transient x - ray pulsar v0332@xmath053 taken with the rossi x - ray timing explorer ( _ rxte _ ) in 2004 december.   we report on the detection of three cyclotron resonance features at 27, 51, and 74kev in the phase - averaged data, corresponding to a polar magnetic field of @xmath1 g.   after 4u0115 + 63, this makes v0332 + 53 the second accreting neutron star in which more than two cyclotron lines have been detected ; this has now also been confirmed by _   integral_. pulse - phase spectroscopy reveals remarkably little variability of the cyclotron line through the 4.4s x - ray pulse.
we establish a network formation game for the internet s autonomous system ( as ) interconnection topology.   the game includes different types of players, accounting for the heterogeneity of ass in the internet.   we incorporate reliability considerations in the player s utility function, and analyze static properties of the game as well as its dynamic evolution.   we provide dynamic analysis of its topological quantities, and explain the prevalence of some `` network motifs '' in the internet graph.   we assess our predictions with real - world data.   # 1
we develop a general microscopic theory of dc josephson effect in hybrid sns structures with ballistic electrodes and spin - active ns interfaces.   we establish a direct relation between the spectrum of andreev levels and the josephson current which contains complete information about non - trivial interplay between andreev reflection and spin - dependent interface scattering.   the system exhibits a rich structure of properties sensitive to spin - dependent barrier transmissions, spin - mixing angles, relative magnetization orientation of interfaces and the kinematic phase of scattered electrons.   we analyze the current - phase relations and identify the conditions for the presence of a @xmath0-junction state in the systems under consideration.   we also analyze resonant enhancement of the supercurrent in gate - voltage - driven nanojunctions.   as compared to the non - magnetic case, this effect can be strongly modified by spin - dependent scattering at ns interfaces.
we analyze the results of the german team handball bundesliga for ten seasons in a model - free statistical time series approach.   we will show that the home advantage is nearly negligible compared to the total sum of goals.   specific interest has been spent on the time evolution of the team fitness expressed in terms of the goal difference.   in contrast to soccer, our results indicate a decay of the team fitness values over a season while the long time correlation behavior over years is nearly comparable.   we are able to explain the dominance of a few teams by the large value for the total number of goals in a match.   a method for the prediction of match winners is presented in good accuracy with the real results.   we analyze the properties of promoted teams and indicate drastic level changes between the bundesliga and the second league.   our findings reflect in good agreement recent discussions on modern successful attack strategies.
using coherence analysis ( which is an extensively used method to study the correlations in frequency domain, between two simultaneously measured signals ) we estimate the time delay between two signals.   this method is suitable for time delay estimation of narrow band coherence signals for which the conventional methods can not be reliably applied.   we show by analysing coupled rssler attractors with a known delay, that the method yields satisfactory results.   then, we apply this method to human pathologic tremor.   the delay between simultaneously measured traces of electroencephalogram ( eeg ) and electromyogram ( emg ) data of subjects with essential hand tremor is calculated.   we find that there is a delay of 11 - 27 milli - seconds ( @xmath0 ) between the tremor correlated parts ( cortex ) of the brain ( eeg ) and the trembling hand ( emg ) which is in agreement with the experimentally observed delay value of 15 @xmath0 for the cortico - muscular conduction time. by surrogate analysis   we calculate error - bars of the estimated delay.   ,   ,  ,   ,    time series, coherence, spectral methods, time delay 05.45.tp, 42.25.kb, 02.70.hm
this work provides an in - depth mathematical description of the response functions that are used for spatial and spectral analysis of x - ray data.   the use of such functions is well - known to anyone familiar with the analysis of x - ray data where they may be identified with the quantities contained in the ancillary response file ( arf ), the redistribution matrix file ( rmf ), and the exposure map.   starting from first - principles, explicit mathematical expressions for these functions, for both imaging and dispersive modes, are arrived at in terms of the underlying instrumental characteristics of the telescope including the effects of pointing motion.   the response functions are presented in the context of integral equations relating the expected detector count rate to the source spectrum incident upon the telescope.   their application to the analysis of several source distributions is considered.   these include multiple, possibly overlapping, and spectrally distinct point sources, as well as extended sources.   assumptions and limitations behind the usage of these functions, as well as their practical computation are addressed.
we study the production of gauge boson pairs at the next generation of linear @xmath0 colliders operating in the @xmath1 mode.   the processes @xmath2 ( @xmath3, @xmath4, or @xmath5 and @xmath6 or @xmath7 ) can give valuable information on possible deviations of the quartic vector boson couplings from the standard model predictions.   we establish the range of the new couplings that can be explored in these colliders based on a @xmath8 effect in the total cross section.   we also present several kinematical distributions of the final state particles that could manifest the underlying new dynamics.   our results show that an @xmath1 collider can extend considerably the bounds on anomalous interactions coming from oblique radiative corrections and from direct searches in @xmath0 colliders.
the bose - einstein condensation of bound pairs made of equally and oppositely charged fermions in a magnetic field is investigated using a relativistic model.   the gaussian fluctuations have been taken into account in order to study the spectrum of bound pairs in the strong coupling region.   we found, in weak coupling reagion, the condensation temperature increases with an increasing magnetic field displaying the magnetic catalysis effect. in strong coupling region,   the inverse magnetic catalysis appears when the magnetic field is low and is replaced by the usual magnetic catalysis effect when magnetic field is sufficiently high, in contrast to the nonrelativistic case where the inverse magnetic catalysis prevails in strong coupling region regardless of the strength of the magnetic field.   the resulting response to the magnetic field is the consequence of the competition between the dimensional reduction by landau orbitals in pairing dynamics and the anisotropy of the kinetic spectrum of the bound pairs.   we thus conclude that dimensional reduction dominates in weak domain and strong coupling one except the small magnetic field region, where the enhanced fluctuations dominates.
even though modern service - oriented and data - oriented architectures promise to deliver loosely coupled control systems, they are inherently brittle as they commonly depend on a priori agreed interfaces and data models. at the same time, the semantic web and a whole set of accompanying standards and tools are emerging, advocating ontologies as the basis for knowledge exchange. in this paper   we aim to identify a number of key ideas from the myriad of knowledge - based practices that can readily be implemented by control systems today.   we demonstrate with a practical example ( a three - channel imager for the mercator telescope ) how ontologies developed in the web ontology language ( owl ) can serve as a meta - model for our instrument, covering as many engineering aspects of the project as needed.   we show how a concrete system model can be built on top of this meta - model via a set of domain specific languages ( dsls ), supporting both formal verification and the generation of software and documentation artifacts  . finally we reason how the available semantics can be exposed at run - time by adding a  semantic layer " that can be browsed, queried, monitored etc. by any opc ua - enabled client.
we review five studies of the gamma - ray burst ( grb ) luminosity function that are based on one or more of the proposed luminosity criteria, i.e., variability, spectral lag and spectral hardness.   a comparison between the resulting luminosity functions at redshift zero shows considerable divergence.   we derive for each of the luminosity functions the expected source counts and the euclidean value of @xmath0.   the source counts exhibit large differences from the observed counts. in most cases   the value of @xmath0 differs substantially from the observed value of 0.34 for batse - based samples, with offsets ranging from @xmath1 sigmas.   given that the value of @xmath0 is well established and that it is a cosmological distance criterion, we recommend that any study of the grb luminosity function take its value into account.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
cryptographic standards serve two important goals : making different implementations interoperable and avoiding various known pitfalls in commonly used schemes.   this chapter discusses public - key cryptography standards ( pkcs ) which have significant impact on the use of public key cryptography in practice.   pkcs standards are a set of standards, called pkcs # 1 through # 15.   these standards cover rsa encryption, rsa signature, password - based encryption, cryptographic message syntax, private - key information syntax, selected object classes and attribute types, certification request syntax, cryptographic token interface, personal information exchange syntax, and cryptographic token information syntax.   the pkcs standards are published by rsa laboratories.   though rsa laboratories solicits public opinions and advice for pkcs standards, rsa laboratories retain sole decision - making authority on all aspects of pkcs standards.   pkcs has been the basis for many other standards such as s / mime.   * key works*. asn.1, public key cryptography, digital signature, encryption, key establishment scheme, public key certificate, cryptographic message syntax, cryptographic token interface ( cryptoki ).
the strong cp problem of qcd is at heart a problem of naturalness : why is the @xmath0 term highly suppressed in the qcd lagrangian when it seems necessary to explain why there are three and not four light pions?   the most elegant solution posits a spontaneously broken peccei - quinn ( pq ) symmetry which requires the existence of the axion field @xmath1.   the axion field settles to the minimum of its potential thus removing the offensive term but giving rise to the physical axion whose coherent oscillations can make up the cold dark matter.   only now are experiments such as admx beginning to explore qcd axion parameter space.   since a bonafide scalar particle the higgs boson has been discovered, one might expect its mass to reside at the axion scale @xmath2 gev.   the higgs mass is elegantly stabilized by supersymmetry : in this case the axion is accompanied by its axino and saxion superpartners.   requiring naturalness also in the electroweak sector implies higgsino - like wimps so then we expect mixed axion - wimp dark matter  . ultimately we would expect detection of both an axion and a wimp while signals for light higgsinos may show up at lhc and must show up at ilc.
we present spatially resolved 3  @xmath0 m spectra of elias  1 obtained with an adaptive optics system.   the central part of the disk is almost devoid of pah emission at 3.3  @xmath0 m ; it shows up only at 30  au and beyond.   the pah emission extends up to 100  au, at least to the outer boundary of our observation.   the diamond emission, in contrast, is more centrally concentrated, with the column density peaked around 30  au from the star.   there are only three herbig ae / be stars known to date that show diamond emission at 3.53  @xmath0 m.   two of them have low - mass companions likely responsible for the large x - ray flares observed toward the herbig ae / be stars.   we speculate on the origin of diamonds in circumstellar disks in terms of the graphitic material being transformed into diamond under the irradiation of highly energetic particles.
we outline major ideas involved in discussion of color coherence phenomena ( ccp ) at intermediate energies.   we point out that the recent advances in calculating cross sections of hard exclusive processes off light nuclei allow to use the lightest nuclei for sensitive tests of ccp.   consistency of the results of the measurements of color transparency in quasielastic a(p,2p ) and a(e, e@xmath0p ) processes is emphasized.   evidence for presence of significant color fluctuations in nucleons and pions emerging from the study of diffractive processes is summarized.   a new class of hard processes leading to three particle final state is suggested for electron and hadron projectiles.   a number of new experiments are suggested to probe color fluctuations in hadrons.
it has proven a significant challenge to experiment and phenomenology to extract precise values of the nucleon sigma terms.   this difficulty opens the window for lattice qcd simulations to lead the field in resolving this aspect of nucleon structure. here   we report on recent advances in the extraction of nucleon sigma terms in lattice qcd.   in particular, the strangeness component is now being resolved to a precision that far surpasses best phenomenological estimates.
these notes are more or less a faithful representation of my talk at the workshop on `` quantum coding and quantum computing '' held at the university of virginia. as such it is an introduction for non - physicists to the topics of the quantum theory of light and entangled states of light. in particular  , i discuss the photon concept and what is really entangled in an entangled state of light ( it is not the photons! ).   moreover, i discuss an example that highlights the peculiar behavior of entanglement in an infinite - dimensional hilbert space.
gamma - ray bursts are believed to originate from internal shocks which arise in an irregular relativistic wind.   the process has been thought to be inefficient, converting only a few percent of the kinetic energy into gamma - rays.   we define ultra efficient internal shocks as those in which the fraction of emitted energy is larger than the fraction of energy given to the radiating electrons at each collision.   we show that such a scenario is possible and even plausible. in our model,   colliding shells which do not emit all their internal energy are reflected from each other and it causes subsequent collisions, allowing more energy to be emitted. as an example, we obtain about @xmath0 overall efficiency even if the fraction of energy that goes to electrons is @xmath1 provided that the shells lorentz factor varies between 10 and @xmath2.   the numerical temporal profile reflects well the activity of the source which ejects the shells, though numerous collisions take place in this model.   # 1 ( # 1 ) # 1\ { # 1 } # 1 # 1#1
we show that the nearest neighbour distribution of distances between basis pairs of some intron - less and intron - containing coding regions are the same when a procedure, called _ unfolding _, is applied.   such a procedure consists in separating the secular variations from the oscillatory terms.   the form of the distribution obtained is quite similar to that of a random, i.e. poissonian, sequence.   this is done for the humbmyh7cd, dromyonma, humbmyh7 and dromhc sequences.   the first two correspond to highly coding regions while the last two correspond to non - coding regions.   we also show that the distributions before the unfolding procedure depend on the secular part but, after the unfolding procedure we obtain an striking result : all distributions are similar to each other. the result becomes independent of the content of introns or the species we have chosen.   this is in contradiction with the results obtained with the detrended fluctuation analysis in which the correlations yield different results for intron - less and intron - containing regions.   spectral statistics, genomic sequences, statistical analysis 87.14.gg, 87.10.+e, 05.40.-a, 87.15.ya
trapping ions in paul traps requires high radio - frequency voltages, which are generated using resonators. when operating traps in a cryogenic environment, an in - vacuum resonator showing low loss is crucial to limit the thermal load to the cryostat. in this study, we present a guide for the design and production of compact, shielded cryogenic resonators.   we produced and characterized three different types of resonators and furthermore demonstrate efficient impedance matching of these resonators at cryogenic temperatures.
most types of supernovae ( sne ) have yet to be connected with their progenitor stellar systems. here, we re - analyze the ten - year 19982008 sn sample collected by the lick observatory supernova search ( loss ) in order to constrain the progenitors of sne ia and stripped - envelope sne ( se  sne ; i.e., sne  iib, ib, ic, and broad - lined ic ).   we matched the loss galaxy sample with spectroscopy from the sloan digital sky survey and measured sn rates as a function of galaxy stellar mass, specific star - formation rate ( ssfr ), and oxygen abundance ( metallicity ).   we find significant correlations between the sn rates and all three galaxy properties.   the sn ia correlations are consistent with other measurements, as well as with our previous explanation of these measurements in the form of a combination of the sn  ia delay - time distribution and the correlation between galaxy mass and age.   intriguingly, we measure a deficiency in the se  sn rates, relative to the sn ii rates, in galaxies with low stellar masses, high ssfr values, and low metallicities. using well - known galaxy scaling relations,   any correlation between the rates and one of the galaxy properties examined here can be expressed as a correlation with the other two.   these redundant correlations preclude us from establishing causality, i.e., from ascertaining which of the galaxy properties ( or their combination ) is the physical driver for the difference between the se  sn and sn  ii rates.
by reaching through shrouding blastwaves, efficiently discovering off - axis events, and probing the central engine at work, gravitational wave ( gw ) observations will soon revolutionize the study of gamma - ray bursts.   already, analyses of gw data targeting gamma - ray bursts have helped constrain the central engines of selected events.   advanced gw detectors with significantly improved sensitivities are under construction. after outlining the gw emission mechanisms from gamma - ray burst progenitors ( binary coalescences, stellar core collapses, magnetars, and others ) that may be detectable with advanced detectors, we review how gws will improve our understanding of gamma - ray burst central engines, their astrophysical formation channels, and the prospects and methods for different search strategies.   we place special emphasis on multimessenger searches. to achieve the most scientific benefit, gw, electromagnetic, and neutrino observations should be combined to provide greater discriminating power and science reach.
we have obtained extensive high - quality spectroscopic observations of the ogle - lmc - cep-1718 eclipsing binary system in the large magellanic cloud which soszynski et al.   ( 2008 ) had identified as a candidate system for containing two classical cepheids in orbit.   our spectroscopic data clearly demonstrate binary motion of the cepheids in a 413-day eccentric orbit, rendering this eclipsing binary system the first ever known to consist of two classical cepheid variables. after disentangling the four different radial velocity variations in the system we present the orbital solution and the individual pulsational radial velocity curves of the cepheids.   we show that both cepheids are extremely likely to be first overtone pulsators and determine their respective dynamical masses, which turn out to be equal to within 1.5 %.   since the secondary eclipse is not observed in the orbital light curve we can not derive the individual radii of the cepheids, but the sum of their radii derived from the photometry is consistent with overtone pulsation for both variables.   the existence of two equal - mass cepheids in a binary system having different pulsation periods ( 1.96 and 2.48 days, respectively ) may pose an interesting challenge to stellar evolution and pulsation theories, and a more detailed study of this system using additional datasets should yield deeper insight about the physics of stellar evolution of cepheid variables.   future analysis of the system using additional near - infrared photometry might also lead to a better understanding of the systematic uncertainties in current baade - wesselink techniques of distance determinations to cepheid variables.
the supermassive black hole at the galactic center, sagittarius a@xmath0, has experienced periods of higher activity in the past. the reflection of these past outbursts is observed in the molecular material surrounding the black hole but reconstructing its precise lightcurve is difficult since the distribution of the clouds along the line of sight is poorly constrained.   + using chandra high - resolution data collected from 1999 to 2011 we studied both the 6.4 kev and the 48 kev emission of the region located between  and the radio arc, characterizing its variations down to 15@xmath1 angular scale and 1-year time scale. the emission from the molecular clouds in the region varies significantly, showing either a 2-year peaked emission or 10-year linear variations.   this is the first time that such fast variations are measured.   based on the cloud parameters, we conclude that these two behaviors are likely due to two distinct past outbursts of  during which its luminosity rose to at least 10@xmath2 erg s@xmath3.
the robustness of multipartite entanglement of systems undergoing decoherence is of central importance to the area of quantum information.   its characterization depends however on the measure used to quantify entanglement and on how one partitions the system.   here we show that the unambiguous assessment of the robustness of multipartite entanglement is obtained by considering the loss of functionality in terms of two communication tasks, namely the splitting of information between many parties and the teleportation of states.
we study metal abundances in the @xmath0 damped ly@xmath1  system observed in the two lines - of - sight, a and b, toward the gravitationally - lensed double qso he0512@xmath23329.   spatially resolved space telescope imaging spectrograph spectra constrain the neutral - gas column density to be @xmath3 ) @xmath4 @xmath5  in both a and b. uv - visual echelle spectrograph spectra ( spectral resolution fwhm @xmath6 km  s@xmath7 ) show, in contrast, significant line - of - sight differences in the column densities of and ; these are not due to observational systematics.   we find that  @xmath8 and  @xmath9 in damped ly@xmath1  system a, while  @xmath10 and  @xmath11, and possibly as high as  @xmath12 in damped ly@xmath1  system b. a careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a @xmath13 level or greater.   although nucleosynthesis effects may also be at play, we favor differential dust - depletion as the main mechanism producing the observed abundance gradient.   the transverse separation is 5 @xmath14kpc at the redshift of the absorber, which is also likely to be the lensing galaxy.   the derived abundances therefore probe two opposite sides of a single galaxy hosting both damped ly@xmath1  systems.   this is the first time firm abundance constraints have been obtained for a single damped system probed by two lines - of - sight.   the significance of this finding for the cosmic
we describe a direct method for monitoring the geometrical dimensions of a synchrotron beam at the target position for internal target installations.   the method allows for the observation of the proton beam size as well as the position of the beam relative to the target. as a first demonstration of the technique, we present results obtained by means of the cosy-11 detection system installed at the cooler synchrotron cosy   the influence of the stochastic cooling on the cosy proton beam dimensions is also investigated.   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,    beam monitoring, internal target, stochastic cooling    29.20.dh, 29.27.-a, 29.27.fh, 25.40.cm
we present a new framework for radiation hydrodynamics simulations.   gas dynamics is modelled by the smoothed particle hydrodynamics ( sph ), whereas radiation transfer is simulated via a time - dependent monte - carlo approach that traces photon packets. as a first step in the development of the method, in this paper we consider the momentum transfer between radiation field and gas, which is important for systems where radiation pressure is high.   there is no fundamental limitations on the number of radiation sources, geometry or the optical depth of the problems that can be studied with the method.   however, as expected for any monte - carlo transfer scheme, stochastic noise presents a serious limitation.   we present a number of tests that show that the errors of the method can be estimated accurately by considering poisson noise fluctuations in the number of photon packets that sph particles interact with per dynamical time.   it is found that for a reasonable accuracy the momentum carried by photon packets must be much smaller than a typical momentum of sph particles.   we discuss numerical limitations of the code, and future steps that can be taken to improve performance and applicability of the method.       physical data and processes : radiative transfer  physical data and processes : hydrodynamics
ferromagnetism in the @xmath0-@xmath1 hubbard model is investigated on a square lattice.   correlation effects in the form of self - energy and vertex corrections are systematically incorporated within a spin - rotationally - symmetric scheme which explicitly preserves the goldstone mode and is therefore in accord with the mermin - wagner theorem.   interplay of band dispersion and correlation effects on ferromagnetic - state stability are highlighted with respect to both long- and short - wavelength fluctuations, which are shown to have substantially different behaviour.   our approach provides a novel understanding of the enhancement of ferromagnetism near van hove filling for @xmath2 in terms of strongly suppressed saddle - point contribution to the destabilizing exchange part of spin stiffness.   finite - temperature electron spin dynamics is investigated directly in terms of spectral - weight transfer across the fermi energy due to electron - magnon coupling.   relevant in the context of recent magnetization measurements on ultrathin films, the role of strong thermal spin fluctuations in low dimensions is highlighted, in the anisotropy - stabilized ordered state, by determining the thermal decay of magnetization and @xmath3 within a renormalized spin - fluctuation theory.
we study the growth of a crystal in presence of a correlated disorder on the substrate. using functional renormalization group,   we show, for a long range disorder correlation, an initial decay of the kpz type nonlinearity, though over a large length scale the behavior can be governed by the nonlinearity.
large arrays of aligned carbon nanotubes ( cnts ), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles ( wimps ). as a result of a wimp elastic scattering on a cnt  , a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice.   the ion may eventually emerge from the surface with open end cnts, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single cnt.   therefore, the angle formed between the wimp wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen.   we focus on very low ion recoil kinetic energies, related to low mass wimps ( @xmath0  gev ) where most of the existing experiments have low sensitivity. relying on some exact results on two - dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to cnt directions.   new constraints are obtained on how to devise the cnt arrays to maximize the detection efficiency.
we examine the evolution of the sizes and number densities of disk galaxies using the high resolution images obtained by the great observatories origins deep survey ( goods ) with the advanced camera for surveys ( acs ) on the _ hubble space telescope ( hst)_. the multiwavelength images are used to classify galaxies based on their rest   frame @xmath0-band morphologies out to redshift @xmath1. in order to minimize the effect of selection biases, we confine our analysis to galaxies which occupy the region of magnitude - size plane where the survey is @xmath2 90% complete at all redshifts.   the observed size distribution is consistent with a log  normal distribution as seen for the disk galaxies in the local universe and does not show any significant evolution over the redshift range @xmath3.   we find that the number densities of disk galaxies remains fairly constant over this redshift range, although a modest evolution by a factor of four may be possible within the 2@xmath4 uncertainties.
we present the first vlbi detection of hcn molecular absorption in the nearby active galactic nucleus ngc  1052. utilizing the 1 mas resolution achieved by the korean vlbi network  , we have spatially resolved the hcn absorption against a double - sided nuclear jet structure.   two velocity features of hcn absorption are detected significantly at the radial velocity of 1656 and 1719 km  s@xmath0, redshifted by 149 and 212 km  s@xmath0 with respect to the systemic velocity of the galaxy.   the column density of the hcn molecule is estimated to be @xmath1@xmath2 @xmath3, assuming an excitation temperature of 100230 k. the absorption features show high optical depth localized on the receding jet side, where the free - free absorption occurred due to the circumnuclear torus.   the size of the foreground absorbing molecular gas is estimated to be on approximately one - parsec scales, which agrees well with the approximate size of the circumnuclear torus.   hcn absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus.   the redshifted velocities of the hcn absorption features imply that hcn absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.
high resolution studies of circular polarization allow us see where it arises in a jet, study its local fractional level and spectrum, and compare these results to local measures of linear polarization and faraday rotation. here   we not only review past results from very long baseline array ( vlba ) circular polarization studies, but we also present preliminary new results on two quasars. in the core of pks 0607@xmath0157  , we find strong circular polarization at 8 ghz and much weaker levels at 15 ghz.   combined with the linear polarization data, we favor a simple model where the circular is produced by faraday conversion driven by a small amount of faraday rotation. in the core of 3c345,   we find strong circular polarization at 15 ghz in a component with distinct linear polarization.   this core component is optically thick at 8 ghz, where we detect no circular polarization. with opposite trends in frequency for pks 0607@xmath0157 and 3c345, it seems clear that local conditions in a jet can have a strong effect on circular polarization and need to be taken into account when studying inhomogeneous objects with multi - frequency observations.
clio ( cryogenic laser interferometer observatory ) is a japanese gravitational wave detector project.   one of the main purposes of clio is to demonstrate thermal - noise suppression by cooling mirrors for a future japanese project, lcgt ( large - scale cryogenic gravitational telescope ).   the clio site is in kamioka mine, as is lcgt.   the progress of clio between 2005 and 2007 ( room- and cryogenic - temperature experiments ) is introduced in this article. in a room - temperature experiment  , we made efforts to improve the sensitivity.   the current best sensitivity at 300 k is about @xmath0 around 400 hz. below 20 hz, the strain ( not displacement ) sensitivity is comparable to that of ligo, although the baselines of clio are 40-times shorter ( clio : 100 m, ligo : 4 km ).   this is because seismic noise is extremely small in kamioka mine.   we operated the interferometer at room temperature for gravitational wave observations.   we obtained 86 hours of data. in the cryogenic experiment  , it was confirmed that the mirrors were sufficiently cooled ( 14 k ).   however, we found that the radiation shield ducts transferred 300k radiation into the cryostat more effectively than we had expected.   we observed that noise caused by pure aluminum wires to suspend a mirror was suppressed by cooling the mirror.
 statistical mechanics is applied to lossy compression using multilayer perceptrons for unbiased boolean messages.   we utilize a tree - like committee machine ( committee tree ) and tree - like parity machine ( parity tree ) whose transfer functions are monotonic. for compression using committee tree,   a lower bound of achievable distortion becomes small as the number of hidden units @xmath0 increases.   however, it can not reach the shannon bound even where @xmath1. for a compression using a parity tree with @xmath2 hidden units,   the rate distortion function, which is known as the theoretical limit for compression, is derived where the code length becomes infinity.
a small depression is created in a straight optical fiber taper to form a local probe suitable for studying closely spaced, planar microphotonic devices.   the tension of the `` dimpled '' taper controls the probe - sample interaction length and the level of noise present during coupling measurements.   practical demonstrations with high-@xmath0 silicon microcavities include testing a dense array of undercut microdisks ( maximum @xmath1@xmath210@xmath3 ) and a planar microring ( @xmath4@xmath210@xmath3 ).
we give sufficient conditions to show that both the group of isometries and the group of measure - preserving isometries of a metric measure space are lie groups.   in addition, we study in which cases spaces satisfying a generalized lower ricci curvature bound satisfy these assumptions.   the conditions are fulfilled in the class of @xmath0-spaces, however, we give an example of an @xmath1-space for which these automorphism groups are not lie groups.   = 1
we present the derivation of a new unidirectional model for unsteady mixed flows in non uniform closed water pipes.   we introduce a local reference frame to take into account the local perturbation caused by the changes of section and slope.   then an asymptotic analysis is performed to obtain a model for free surface flows and another one for pressurized flows. by coupling these models through the transition points by the use of a common set of variables and a suitable pressure law,   we obtain a simple formulation called pfs - model close to the shallow water equations with source terms.   it takes into account the changes of section and the slope variation in a continuous way through transition points.   transition point between the two types of flows is treated as a free boundary associated to a discontinuity of the gradient of pressure.   the numerical simulation is performed by making use of a roe - like finite volume scheme that we adapted to take into account geometrical source terms in the convection matrix. finally some numerical tests are presented.   * keywords * : shallow water, mixed flows, free surface flows, pressurized flows, curvilinear transformation, asymptotic analysis, vfroe scheme, well - balanced finite volume scheme, hyperbolic system with source terms.
we present results from _ chandra _ and _ xmm - newton _   spectroscopic observations of the nuclei of @xmath0 radio galaxies and quasars from the 3crr catalog, and examine in detail the dichotomy in the properties of low- and high - excitation radio galaxies.   the x - ray spectra of low - excitation sources ( those with weak or absent optical emission lines ) are dominated by unabsorbed emission from a parsec - scale jet, with no contribution from accretion - related emission.   these sources show no evidence for an obscuring torus, and are likely to accrete in a radiatively inefficient manner.   high - excitation sources ( those with prominent optical emission lines ), on the other hand, show a significant contribution from a radiatively efficient accretion disk, which is heavily absorbed in the x - ray when they are oriented close to edge - on with respect to the observer.   however, the low - excitation / high - excitation division does not correspond to the fri / frii division : thus the fanaroff - riley dichotomy remains a consequence of the interaction between the jet and the hot - gas environment through which it propagates.   finally, we suggest that accretion of the hot phase of the igm is sufficient to power _ all _ low - excitation radio sources, while high - excitation sources require an additional contribution from cold gas that in turn forms the cold disk and torus. this model explains a number of properties of the radio - loud active galaxy population, and has important implications for agn feedback mechanisms.
we investigate the correlation between the point disclination energies and the surface curvature modulation of nematic liquid crystal membranes with a gaussian bump geometry. due to the correlation  , disclinations feel an attractive force that confines them to an annulus region, resulting in a halo distribution around the top of the bump.   the halo formation is a direct consequence of the nonzero gaussian curvature of the bump that affects preferable configurations of liquid crystal molecules around the disclination core.
we demonstrate that the angular distribution of photoelectrons from a strongly polarizable target exposed to a laser field can deviate noticeably from the prediction of conventional theory. even within the dipole - photon approximation   the profile of distribution is modified due to the action of the field of alternating dipole moment induced at the residue by the laser field.   this effect, being quite sensitive to the dynamic polarizability of the residue and to its geometry, depends also on the intensity and frequency of the laser field.   numerical results, presented for sodium cluster anions, demonstrate that dramatic changes to the profile occur for the photon energies in vicinities of the plasmon resonances, where the effect is enhanced due to the increase in the residue polarizability.   strong modifications of the characteristics of a single - photon ionization process can be achieved by applying laser fields of comparatively low intensities @xmath0 w/@xmath1.
for a system strongly coupled to a heat bath, the quantum coherence of the system and the heat bath plays an important role in the system dynamics.   this is particularly true in the case of non - markovian noise.   we rigorously investigate the influence of system - bath coherence by deriving the reduced hierarchal equations of motion ( heom ), not only in real time, but also in imaginary time, which represents an inverse temperature.   it is shown that the heom in real time obtained when we include the system - bath coherence of the initial thermal equilibrium state possess the same form as those obtained from a factorized initial state.   we find that the difference in behavior of systems treated in these two manners results from the difference in initial conditions of the heom elements, which are defined in path integral form.   we also derive heom along the imaginary time path to obtain the thermal equilibrium state of a system strongly coupled to a non - markovian bath.   then, we show that the steady state hierarchy elements calculated from the real - time heom can be expressed in terms of the hierarchy elements calculated from the imaginary - time heom. moreover, we find that the imaginary - time heom allow us to evaluate a number of thermodynamic variables, including the free energy, entropy, internal energy, heat capacity, and susceptibility.   the expectation values of the system energy and system - bath interaction energy in the thermal equilibrium state are also evaluated.
we present a simple combinatorial model for the characters of the irreducible integrable highest weight modules for complex symmetrizable kac - moody algebras.   this model can be viewed as a discrete counterpart to the littelmann path model.   we describe crystal graphs and give a littlewood - richardson rule for decomposing tensor products of irreducible representations.   the new model is based on the notion of a @xmath0-chain, which is a chain of positive roots defined by certain interlacing conditions.
we report the possible discovery of multiple gravitationally - lensed images of qsos with angular separations on arcminute scales.   the qsos were selected from the completed 2df qso survey as having redshifts and optical colours which are statistically consistent. in this paper   we present higher - quality optical spectra of the candidates and discuss the likelihood of their genuinely being systems lensed by massive clusters of galaxies. from a comparison of the spectra it appears that up to six pairs of qsos may be lensed multiple images, although the true number may be less than that and further observations should be undertaken to amass more evidence and to detect the lensing clusters.   two of the candidates may be associated with low redshift clusters of galaxies.       gravitational lenses  qsos.
ultra high energy ( uhe ) particles of cosmic origin impact the lunar regolith and produce radio signals through askaryan effect, signals that can be detected by earth based radio telescopes.   we calculate the expected sensitivity for observation of such events at the giant metrewave radio telescope ( gmrt ), both for uhe cosmic rays ( cr ) and uhe neutrino interactions.   we find that for 30 days of observation time a significant number of detectable events is expected above @xmath0 ev for uhecr or neutrino fluxes close to the current limits.   null detection over a period of 30 days will lower the experimental bounds by a magnitude competitive to both present and future experiments at the very highest energies.
the ability to categorize problems is a measure of expertise in a domain. in order to help students   learn effectively, instructors and teaching assistants ( tas ) should have pedagogical content knowledge.   they must be aware of the prior knowledge of students they are teaching, consider the difficulty of the problems from students perspective and design instruction that builds on what students already know. here, we discuss the response of graduate students enrolled in a ta training course to categorization tasks in which they were asked to group problems based upon similarity of solution first from their own perspective, and later from the perspective of introductory physics students.   many graduate students performed an expert - like categorization of introductory physics problems.   however, when asked to categorize the same problems from the perspective of introductory students, many graduate students expressed dismay, claiming that the task was impossible, pointless and had no relevance to their ta duties. we will discuss how categorization can be a useful tool for scaffolding and improving pedagogical content knowledge of teaching assistants and instructors.   address = department of physics and astronomy, university of pittsburgh, pittsburgh, pa, 15260, usa
we propose to use a quantum ratchet to transport quantum information in a chain of atoms trapped in an optical superlattice.   the quantum ratchet is created by a continuous modulation of the optical superlattice which is periodic in time and in space. though there is zero average force acting on the atoms,   we show that indeed the ratchet effect permits atoms on even and odd sites to move along opposite directions. by loading the optical lattice with two - level bosonic atoms, this scheme permits to perfectly   transport a qubit or entangled state imprinted in one or more atoms to any desired position in the lattice. from the quantum computation point of view  , the transport is achieved by a smooth concatenation of perfect swap gates.   we analyze setups with noninteracting and interacting particles and in the latter case we use the tools of optimal control to design optimal modulations.   we also discuss the feasibility of this method in current experiments.
in the collapsar model for common gamma - ray bursts, the formation of a centrifugally supported disk occurs during the first @xmath010 seconds following the collapse of the iron core in a massive star.   this only occurs in a small fraction of massive stellar deaths, however, and requires unusual conditions.   a much more frequent occurrence could be the death of a star that makes a black hole and a weak or absent outgoing shock, but in a progenitor that only has enough angular momentum in its outermost layers to make a disk.   we consider several cases where this is likely to occur - blue supergiants with low mass loss rates, tidally - interacting binaries involving either helium stars or giant stars, and the collapse to a black hole of very massive pair - instability supernovae.   these events have in common the accretion of a solar mass or so of material through a disk over a period much longer than the duration of a common gamma - ray burst.   a broad range of powers is possible, @xmath1 to @xmath2erg s@xmath3, and this brightness could be enhanced by beaming.   such events were probably more frequent in the early universe where mass loss rates were lower.   indeed this could be one of the most common forms of gamma - ray transients in the universe and could be used to study first generation stars.   several events could be active in the sky at any one time.   a recent example of this sort of event may have been the swift transient sw-1644 + 57.
after briefly describing the present status of the spin glass theory, we present a conjecture on the exact location of the multicritical point in the phase diagram of finite - dimensional spin glasses.   the theory enables us to understand in a unified way many numerical results for two-, three- and four - dimensional models including the @xmath0 ising model, random potts model, random lattice gauge theory, and random @xmath1 model.   it is also suggested from the same theoretical framework that models with symmetric distribution of randomness in exchange interaction have no finite - temperature transition on the square lattice.
we study transport in two - terminal metal / quantum spin - hall insulator ( qshi)/metal junctions.   we show that the conductance signals originating from the bulk and the edge contributions are not additive.   while for a long junction the transport is determined by the edge states contribution, for a short junction, the conductance signal is built from both bulk and edge states in the ratio which depends on the width of the sample.   further, in the topological insulator regime the conductance for short junctions shows a non - monotonic behavior as a function of the sample length.   surprisingly this non - monotonic behavior of conductance can be traced to the formation of an effectively propagating solution which is robust against scalar disorder.   our predictions should be experimentally verifiable in hgte qws and bi@xmath0se@xmath1 thin films.
we investigate the influence of the geometry of the solar filament magnetic structure on the large - amplitude longitudinal oscillations.   a representative filament flux tube is modeled as composed of a cool thread centered in a dipped part with hot coronal regions on either side.   we have found the normal modes of the system, and establish that the observed longitudinal oscillations are well described with the fundamental mode. for small and intermediate curvature radii and moderate to large density contrast between the prominence and the corona, the main restoring force is the solar gravity. in this full wave description of the oscillation   a simple expression for the oscillation frequencies is derived in which the pressure - driven term introduces a small correction.   we have also found that the normal modes are almost independent of the geometry of the hot regions of the tube.   we conclude that observed large - amplitude longitudinal oscillations are driven by the projected gravity along the flux tubes, and are strongly influenced by the curvature of the dips of the magnetic field in which the threads reside.
spiral wave, whose rotation center can be regarded as a point defect, widely exists in various two dimensional excitable systems. in this paper, by making use of _ duan s topological current theory _, we obtain the charge density of spiral waves and the topological inner structure of its topological charge.   the evolution of spiral wave is also studied from the topological properties of a two - dimensional vector field.   the spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two - dimensional vector field.   some applications of our theory are also discussed.
we present the formulation for finding the distribution of eigenstrains, i.e. the sources of residual stress, from a set of measurements of residual elastic strain ( e.g. by diffraction ), or residual stress, or stress redistribution, or distortion.   the variational formulation employed seeks to achieve the best agreement between the model prediction and some measured parameters in the sense of a minimum of a functional given by a sum over the entire set of measurements.   the advantage of this approach lies in its flexibility : different sets of measurements and information about different components of the stress - strain state can be incorporated.   we demonstrate the power of the technique by analysing experimental data for welds in thin sheet of a nickel superalloy aerospace material.   very good agreement can be achieved between the prediction and the measurement results without the necessity of using iterative solution. in practice   complete characterisation of residual stress states is often very difficult, due to limitations of facility access, measurement time or specimen dimensions.   implications of the new technique for experimental analysis are all the more significant, since it allows the reconstruction of the entire stress state from incomplete sets of data.
we consider effects of inter - species attraction on two - component gap solitons ( gss ) in the binary bec with intra - species repulsion, trapped in the one - dimensional optical lattice ( ol ).   systematic simulations of the coupled gross - pitaevskii equations ( gpes ) corroborate an assumption that, because the effective mass of gss is negative, the inter - species attraction may _ split _ the two - component soliton.   two critical values, @xmath0 and @xmath1, of the ol strength ( @xmath2 ) are identified.   two - species gss with fully overlapping wave functions are stable in strong lattices ( @xmath3 ). in an intermediate region, @xmath4,   the soliton splits into a double - humped state with separated components.   finally, in weak lattices ( @xmath5 ), the splitting generates a pair of freely moving single - species gss.   we present and explain the dependence of @xmath6 and @xmath1 on thenumber of atoms ( total norm ), and on the relative strength of the competing inter - species attraction and intra - species repulsion.   the splitting of asymmetric solitons, with unequal norms of the two species, is briefly considered too.   it is found and explained that the splitting threshold grows with the increase of the asymmetry.
it has been suggested that the narrow cores of the fe k@xmath0 emission lines in active galactic nuclei ( agns ) are likely produced in the torus, the inner radius of which can be measured by observing the lag time between the @xmath1 and @xmath2 band flux variations. in this paper, we compare the virial products of the infrared time lags, and the narrow fe k@xmath0 widths for 10 type 1 agns, with the black hole masses from other techniques.   we found the narrow fe k@xmath0 line width is in average 2.6@xmath3 times broader than expected, assuming an isotropic velocity distribution of the torus at the distance measured by the infrared lags.   we propose the thick disk model of the torus may explain the observed larger line width.   another possibility is the contamination by emission from the broad line region or the outer accretion disk.   alternatively, the narrow iron line might originate from the inner most part of the obscuring torus within the sublimation radius, while the infrared emission may be from the outer cooler part.   we note the correlations between the black hole masses based on this new technique and those based on other known techniques are statistically insignificant.   we argue that this could be attributed to the small sample size and the very large uncertainties in the measurements of iron k line widths.   the next generation of x - ray observatories could help verify the origin of the narrow iron k@xmath0 line and the reliability of this new technique.
we propose a model - independent scaling method to study the physical properties of high - temperature superconductors in the normal state.   we have analyzed the experimental data of the c - axis resistivity, the in - plane resistivity, the hall coefficient, the magnetic susceptibility, the spin - lattice relaxation rate, and the thermoelectric power using this method.   it is shown that all these physical quantities exhibit good scaling behaviors, controlled purely by the pseudogap energy scale in the normal state.   the doping dependence of the pseudogap obtained from this scaling analysis agrees with the experimental results of angle - resolved photoemission and other measurements.   it sheds light on the understanding of the basic electronic structure of high-@xmath0 oxides.
we study theoretically the feasibility of using transverse electronic transport within a nanopore for rapid dna sequencing.   specifically, we examine the effects of the environment and detection probes on the distinguishability of the dna bases.   we find that the intrinsic measurement bandwidth of the electrodes helps the detection of single bases by averaging over the current distributions of each base.   we also find that although the overall magnitude of the current may change dramatically with different detection conditions, the intrinsic distinguishability of the bases is not significantly affected by pore size and transverse field strength.   the latter is the result of very effective stabilization of the dna by the transverse field induced by the probes, so long as that field is much larger than the field that drives dna through the pore.   in addition, the ions and water together effectively screen the charge on the nucleotides, so that the electron states participating in the transport properties of the latter ones resemble those of the uncharged species. finally, water in the environment has negligible direct influence on the transverse electrical current.
we present results of radial - velocity follow - up observations for the two _ kepler _ evolved stars kepler-91 ( koi-2133 ) and koi-1894, which had been announced as candidates to host transiting giant planets, with the subaru 8.2 m telescope and the high dispersion spectrograph ( hds ). by global modeling of the high - precision radial - velocity data taken with subaru / hds and photometric ones taken by _   kepler _   mission taking account of orbital brightness modulations ( ellipsoidal variations, reflected / emitted light, etc. ) of the host stars, we independently confirmed that kepler-91 hosts a transiting planet with a mass of @xmath0 ( kepler-91b ), and newly detected an offset of @xmath120 m s@xmath2 between the radial velocities taken at @xmath3-yr interval, suggesting the existence of additional companion in the system.   as for koi-1894, we detected possible phased variations in the radial velocities and light curves with 23@xmath4 confidence level which could be explained as a reflex motion and ellipsoidal variation of the star caused by the transiting sub - saturn - mass ( @xmath5 ) planet.
the coulomb repulsion between ions in a linear paul trap give rise to anharmonic terms in the potential energy when expanded about the equilibrium positions.   we examine the effect of these anharmonic terms on the accuracy of a quantum simulator made from trapped ions. to be concrete, we consider a linear chain of @xmath0 ions stabilized close to the zigzag transition.   we find that for typical experimental temperatures, frequencies change by no more than a factor of @xmath1 due to the anharmonic couplings.   furthermore, shifts in the effective spin - spin interactions ( driven by a spin - dependent optical dipole force ) also tend to be small for detunings to the blue of the transverse center - of - mass frequency.   however, detuning the spin interactions near other frequencies can lead to nonnegligible anharmonic contributions to the effective spin - spin interactions.   we also examine an odd behavior exhibited by the harmonic spin - spin interactions for a range of intermediate detunings, where nearest neighbor spins with a larger spatial separation on the ion chain interact more strongly than nearest neighbors with a smaller spatial separation.
we use @xmath0 paths to construct a process of continuum nonsimple loops in the plane and prove that this process coincides with the full continuum scaling limit of 2d critical site percolation on the triangular lattice  that is, the scaling limit of the set of all interfaces between different clusters.   some properties of the loop process, including conformal invariance, are also proved.   * keywords : * continuum scaling limit, percolation, sle, critical behavior, triangular lattice, conformal invariance.   * ams 2000 subject classification : * 82b27, 60k35, 82b43, 60d05, 30c35.
we consider renormalisable models extended in the scalar sector by a generic scalar field in addition to the standard model higgs boson field, and work out the effective theory for the latter in the decoupling limit.   we match the full theory onto the effective theory at tree and one - loop levels, and concentrate on dimension-6 operators of the higgs and electroweak gauge fields induced from such matching.   the wilson coefficients of these dimension-6 operators from tree - level matching are further improved by renormalisation group running. for specific @xmath0 representations of the scalar field, some `` accidental '' couplings with the higgs field   are allowed and can lead to dimension-6 operators at tree and/or one - loop level.   otherwise, two types of interaction terms are identified to have only one - loop contributions, for the wilson coefficients of which we have obtained a general formula. using the obtained results, we analyse constraints from electroweak oblique parameters and the higgs data on several phenomenological models.   ipmu15 - 0073 +
the source of the very bright gamma - ray burst grb 030329 is close enough to us for there to be a hope to measure or significantly constrain its putative superluminal motion.   such a phenomenon is expected in the `` cannonball '' ( cb ) model of grbs.   recent precise data on the optical and radio afterglow of this grb which demonstrated its very complex structure allow us to pin down the cb - model s prediction for the afterglow - source position as a function of time.   it has been stated that ( the unpublished part of ) the new radio data `` unequivocably disprove '' the cb model.   we show how greatly exaggerated that obituary announcement was, and how precise a refined analysis of the data would have to be, to be still of interest.   -1 cm
we report the observation and the theoretical explanation of the parametric down - conversion nonlinear susceptibility at the @xmath0-absorption edge of diamond and at the @xmath1-absorption edge of a silicon crystal. using arguments similar to those invoked to successfully predict resonant inelastic x - ray spectra  , we derive an expression for the renormalization term of the non - linear susceptibility at the x - ray edges, which can be evaluated by using first - principles calculations of the atomic scattering factor @xmath2.   our model is shown to reproduce the observed enhancement of the parametric down - conversion at the diamond @xmath0 and the si @xmath1 edges rather than the suppression previously claimed.
we present long - slit spectroscopic data which reveals extended ly@xmath0  emission around the @xmath1 radio - quiet quasar cfhqsj2329 - 0301.   the ly@xmath0  emission is extended over 15kpc and has a luminosity of @xmath2w, comparable to the most luminous ly@xmath0  halos known.   the emission has complex kinematics, in part due to foreground absorption which only partly covers the extended nebula.   the velocity ranges from @xmath3kms@xmath4 to @xmath5kms@xmath4, with a peak remarkably close to the systemic velocity identified by broad mgii  emission of the quasar.   there is no evidence for infall or outflow of the halo gas.   we speculate that the ly@xmath0  emission mechanism is recombination after quasar photo - ionization of gas sitting within a high - mass dark matter halo.   the immense ly@xmath0  luminosity indicates a higher covering factor of cold gas compared to typical radio - quiet quasars at lower redshift.
we compute the shift in the frequency of the spin resonance in a solid that rotates in the field of a circularly polarized electromagnetic wave. electron spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are considered.   we show that contrary to the case of the rotating lc circuit, the shift in the frequency of the spin resonance has strong dependence on the symmetry of the receiver.   the shift due to rotation occurs only when rotational symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape of the body, or by magnetocrystalline anisotropy.   general expressions for the resonance frequency and power absorption are derived and implications for experiment are discussed.
quantum hall ( qh ) and quantum spin hall ( qsh ) phases have very different edge states and, when going from one phase to the other, the direction of one edge state must be reversed.   we study this phenomenon in graphene in presence of a strong perpendicular magnetic field on top of a spin - orbit ( so ) induced qsh phase.   we show that, below the so gap, the qsh phase is virtually unaffected by the presence of the magnetic field. above the so gap,   the qh phase is restored.   an electrostatic gate placed on top of the system allows to create a qsh - qh junction which is characterized by the existence of a spin - polarized chiral state, propagating along the topological interface.   we find that such a setup naturally provides an extremely sensitive spin - polarized current switch.
the performance of collaborative beamforming is analyzed using the theory of random arrays.   the statistical average and distribution of the beampattern of randomly generated phased arrays is derived in the framework of wireless ad hoc sensor networks.   each sensor node is assumed to have a single isotropic antenna and nodes in the cluster collaboratively transmit the signal such that the signal in the target direction is coherently added in the far - field region.   it is shown that with @xmath0 sensor nodes uniformly distributed over a disk, the directivity can approach @xmath0, provided that the nodes are located sparsely enough.   the distribution of the maximum sidelobe peak is also studied. with the application to ad hoc networks in mind,   two scenarios, closed - loop and open - loop, are considered.   associated with these scenarios, the effects of phase jitter and location estimation errors on the average beampattern are also analyzed.   _ to appear in ieee transactions on signal processing, 2005.
rotochemical heating originates in a departure from beta equilibrium due to spin - down compression in a rotating neutron star.   the main consequence is that the star eventually arrives at a quasi - equilibrium state, in which the thermal photon luminosity depends only on the current value of the spin - down power, which is directly measurable. only in millisecond   pulsars the spin - down power remains high long enough for this state to be reached with a substantial luminosity.   we report an extensive study of the effect of this heating mechanism on the thermal evolution of millisecond pulsars, developing a general formalism in the slow - rotation approximation of general relativity that takes the spatial structure of the star fully into account, and using a sample of realistic equations of state to solve the non - superfluid case numerically.   we show that nearly all observed millisecond pulsars are very likely to be in the quasi - equilibrium state.   our predicted quasi - equilibrium temperatures for psr j0437 - 4715 are only 20% lower than inferred from observations.   accounting for superfluidity should increase the predicted value.
the human brain processes information showing learning and prediction abilities but the underlying neuronal mechanisms still remain unknown. recently, many studies prove that neuronal networks are able of both generalizations and associations of sensory inputs.   + in this paper, following a set of neurophysiological evidences, we propose a learning framework with a strong biological plausibility that mimics prominent functions of cortical circuitries.   we developed the inductive conceptual network ( icn ), that is a hierarchical bio - inspired network, able to learn invariant patterns by variable - order markov models implemented in its nodes.   the outputs of the top - most node of icn hierarchy, representing the highest input generalization, allow for automatic classification of inputs.   we found that the icn clusterized mnist images with an error of 5.73% and usps images with an error of 12.56%.   recognition ; handwritten digits ; abstraction process ; hierarchical network
we analyze a mathematical model of the epizootic of hantavirus in mice population, including the effect of species which compete with the host.   we show that the existence of the second species has an important consequence for the prevalence of the infectious agent in the host.   when the two mice species survive in the ecosystem, the competitive pressure of the second species may lead to reduction or complete elimination of the prevalence of infection.   the transition between the disappearance of the infection and its presence occurs at a critical value of the competitor s population, resembling a second order phase transition in a statistical system.   the results provide a rigorous framework for the study of the impact of biodiversity in the propagation of infectious diseases, and further lends itself to future experimental verification.
using 3d radiative transfer calculations on the reionization of an inhomogeneous universe, qso absorption line systems are simulated and they are compared with observations of ly@xmath0 continuum depression at high redshifts. by this comparison, it is found that the metagalactic uv intensity decreases rapidly with @xmath1 at @xmath2 as @xmath3 $ ], and the reionization must have taken place between @xmath4 and 10.   based on this time - dependence of uv background intensity, we explore the collapse of pregalactic clouds in the uv background, and find that the self - shielding is prominent above a mass scale as @xmath5^{-4.2}(i_{21}/0.5)^{0.6}. $ ] this mass scale predicts the bifurcation of galactic morphology, and by confrontation with observations it turns out that the bifurcation mass successfully discriminates between elliptical and spiral galaxies.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study the conformational properties of heteropolymers containing two types of monomers @xmath0 and @xmath1, modeled as self - avoiding random walks on a regular lattice.   such a model can describe in particular the sequences of hydrophobic and hydrophilic residues in proteins ( k.f.   lau and k.a.   dill, macromolecules * 22 *, 3986 ( 1989 ) ) and polyampholytes with oppositely charged groups ( y. kantor and m. kardar, europhys.   lett.   * 28 *, 169 ( 1994 ) ). treating the sequences of the two types of monomers as quenched random variables, we provide a systematic analysis of possible generalizations of this model. to this end   we apply the pruned - enriched rosenbluth chain - growth algorithm ( perm ), which allows us to obtain the phase diagrams of extended and compact states coexistence as function of both the temperature and fraction of @xmath0 and @xmath1 monomers along the heteropolymer chain.
we study two - dimensional @xmath0 @xmath1 super yang - mills theory on euclidean two - torus using sugino s lattice regularization.   we perform the monte - carlo simulation for @xmath2 and then extrapolate the result to @xmath3. with the periodic boundary conditions for the fermions along both circles, we establish the existence of a bound state in which scalar fields clump around the origin, in spite of the existence of a classical flat direction. in this phase   the global @xmath4 symmetry turns out to be broken.   we provide a simple explanation for this fact and discuss its physical implications.   dftt44/2009 + wis/09/09-june - dpp + riken - th-161     +     masanori hanada@xmath5 and issaku kanamori@xmath6 + @xmath7    _ department of particle physics, weizmann institute of science _   rehovot 76100, israel     + @xmath8    _ theoretical physics laboratory, riken nishina center _   wako, saitama 351 - 0198, japan     + @xmath9 _ dipartimento di fisica teorica, universit di torino, via giuria 1, 10125 torino, italy _ +
the surface current method known in the theory of electromagnetic waves diffraction is generalized to be applied for the problems of diffraction radiation generated by a charged particle moving nearby an ideally - conducting screen in vacuum.   an expression for induced surface current density leading to the exact results in the theory of transition radiation is derived, and by using this expression several exact solutions of diffraction radiation problems are found.   limits of applicability for the earlier known models based on the surface current conception are indicated.   properties of radiation from a semi - plane and from a slit in cylinder are investigated at the various distances to observer.   diffraction radiation, transition radiation, surface current, pre - wave zone effect    41.60.dk, 42.25.fx, 78.70.gq
we perform the complete stability study of the model of chromo - natural inflation ( adshead and wyman 12 ), where, due to its coupling to a su(2 ) vector, a pseudo - scalar inflaton @xmath0 slowly rolls on a steep potential. as a typical example  , one can consider an axion with a sub - planckian decay constant @xmath1.   the model was recently studied ( dimastrogiovanni, fasiello, and tolley 12 ) in the @xmath2 limit, where @xmath3 is the mass of the fluctuations of the vector field, and @xmath4 the hubble rate.   we show that the inflationary solution is stable for @xmath5, while it otherwise experiences a strong instability due to scalar perturbations in the sub - horizon regime.   the tensor perturbations are instead enhanced at large @xmath3, while the vector ones remain perturbatively small.   depending on the parameters, this model can give a chiral gravity wave signal that can be detected in ongoing or forthcoming cmb experiments.   this detection can occur even if, during inflation, the inflaton spans an interval of size @xmath6 which is some orders of magnitude below the planck scale, evading a well known bound that holds for a free inflaton ( lyth 97 ).   the spectral tilt of the scalar perturbations typically decreases with decreasing @xmath3  . therefore the simultaneous requirements of stability, sufficiently small tensor - to - scalar ratio, and sufficiently flat scalar spectrum can pose nontrivial bounds on the parameters of the model.   -2 cm
part v of the second edition of pierre rmond de montmort s _ essay danalyse sur les jeux de hazard _ published in 1713 contains correspondence on probability problems between montmort and nicolaus bernoulli.   this correspondence begins in 1710.   the last published letter, dated november 15, 1713, is from montmort to nicolaus bernoulli.   there is some discussion of the strategy of play in the card game le her and a bit of news that montmort s friend waldegrave in paris was going to take care of the printing of the book. from earlier correspondence between bernoulli and montmort,   it is apparent that waldegrave had also analyzed le her and had come up with a mixed strategy as a solution.   he had also suggested working on the `` problem of the pool, '' or what is often called waldegrave s problem.   the universittsbibliothek basel contains an additional forty - two letters between bernoulli and montmort written after 1713, as well as two letters between bernoulli and waldegrave.   the letters are all in french, and here we provide translations of key passages.   the trio continued to discuss probability problems, particularly le her which was still under discussion when the _ essay danalyse _ went to print.   we describe the probability content of this body of correspondence and put it in its historical context.   we also provide a proper identification of waldegrave based on manuscripts in the archives nationales de france in paris.
the problem of noise - induced escape from a metastable state arises in physics, chemistry, biology, systems engineering, and other areas. the problem is well understood when the underlying dynamics of the system obey detailed balance.   when this assumption fails many of the results of classical transition - rate theory no longer apply, and no general method exists for computing the weak - noise asymptotics of fundamental quantities such as the mean escape time. in  this paper   we  present a general technique for analysing the weak - noise limit of a wide range of stochastically perturbed continuous - time nonlinear dynamical systems.   we  simplify the original problem, which involves solving a partial differential equation, into one in  which only ordinary differential equations need be solved.   this allows us to resolve some old issues for the case when detailed balance holds.   when it does not hold, we  show how the formula for the mean escape time asymptotics depends on the dynamics of the system along the most probable escape path.   we  also present new results on short - time behavior and discuss the possibility of _ focusing _ along the escape path.   the escape problem for irreversible systems    mathematics@xmath0 and physics@xmath1 departments, university of arizona, tucson, az  85721
we study the magnetic properties of @xmath0 antiferromagnetic heisenberg chains with inhomogeneity of interaction. using a quantum monte carlo method and an exact diagonalization method, we study bond - impurity effect in the uniform @xmath0 chain and also in the bond - alternating chain. here   bond impurity means a bond with strength different from those in the bulk or a defect in the alternating order.   local magnetic structures induced by bond impurities are investigated both in the ground state and at finite temperatures, calculating the local magnetization, the local susceptibility and the local field susceptibility.   we also investigate the force acting between bond impurities and find the force generally attractive.
we study the generation and evolution of gravitational waves ( tensor perturbations ) in the context of randall - sundrum braneworld cosmology.   we assume that the initial and final stages of the background cosmological model are given by de sitter and minkowski phases, respectively, and they are connected smoothly by a radiation - dominated phase.   this setup allows us to discuss the quantum - mechanical generation of the perturbations and to see the final amplitude of the well - defined zero mode. using the wronskian formulation, we numerically compute the power spectrum of gravitational waves, and find that the effect of initial vacuum fluctuations in the kaluza - klein modes is subdominant, contributing not more than 10% of the total power spectrum.   thus it is confirmed that the damping due to the kaluza - klein mode generation and the enhancement due to the modification of the background friedmann equation are the two dominant effects, but they cancel each other, leading to the same spectral tilt as the standard four - dimensional result.   kaluza - klein gravitons that escape from the brane contribute to the energy density of the dark radiation at late times. we show that a tiny amount of the dark radiation is generated due to this process.
background : the reconstruction of the phylogenetic tree topology of four taxa is, still nowadays, one of the main challenges in phylogenetics.   its difficulties lie in considering not too restrictive evolutionary models, and correctly dealing with the long - branch attraction problem.   the correct reconstruction of 4-taxon trees is crucial for making quartet - based methods work and being able to recover large phylogenies.    results : in this paper we consider an expectation - maximization method for maximizing the likelihood of ( time nonhomogeneous ) evolutionary markov models on trees.   we study its success on reconstructing 4-taxon topologies and its performance as input method in quartet - based phylogenetic reconstruction methods such as qfit and quartetsuite.   our results show that the method proposed here outperforms neighbor - joining and the usual ( time - homogeneous continuous - time ) maximum likelihood methods on 4-leaved trees with among - lineage instantaneous rate heterogeneity, and perform similarly to usual continuous - time maximum - likelihood when data satisfies the assumptions of both methods.   conclusions : the method presented in this paper is well suited for reconstructing the topology of any number of taxa via quartet - based methods and is highly accurate, specially regarding largely divergent trees and time nonhomogeneous data.   * keywords : tree topology reconstruction, expectation - maximization, quartet - based method, evolutionary markov model *    
a classical spinning particle based on the kerr - newman black hole ( bh ) solution is considered. for parameters of spinning particles @xmath0,   the bh horizons disappear and bh image is drastically changed.   we show that it turns into a skeleton formed by two coupled stringy systems.   one of them is the kerr singular ring which can be considered as a circular d - string with an orientifold world - sheet. analyzing the aligned to the kerr congruence electromagnetic excitations of this string  , we obtain the second stringy system which consists of two axial half - infinite chiral d - strings.   these axial strings are similar to the dirac monopole strings but carry the induced chiral traveling pp - waves.   their field structure can be described by the field model suggested by witten for the cosmic superconducting strings.   we discuss a relation of this stringy system to the dirac equation and argue that this stringy system can play a role of a classical carrier of the wave function.   ~ 3|y_,3 3y_,3 `
the dynamics of an atomic few - level system can depend on the phase of driving fields coupled to the atom if certain conditions are satisfied.   this is of particular interest to control interference effects, which can alter the system properties considerably. in this article  , we discuss the mechanisms of such phase control and interference effects in an atomic three - level system in @xmath0 configuration, where the upper state spontaneously decays into the two lower states.   the lower states are coupled by a driving field, which we treat as quantized.   this allows for an interpretation on the single photon level for both the vacuum and the driving field. by analyzing the system behavior for a driving field initially in non - classical states with only few fock number states populated,   we find that even though the driving field is coupled to the lower states only, it induces a multiplet of upper states.   then interference occurs independently in three - level subsystems in @xmath1 configuration, each formed by two adjacent upper states and a single dressed lower state.
the hegra system of imaging atmospheric cherenkov telescopes provides for specially selected classes of events an angular resolution of better than 3. by comparing the measured angular distribution of tev gamma rays from the crab nebula with the distribution expected on the basis of monte carlo simulations, and with measurements of gamma rays from the point source mrk 501, we conclude that the rms size of the vhe gamma - ray emission region in the crab nebula is less than 1.5.
we present _ spitzer space telescope _ time series photometry of the exoplanet system hd  189733 spanning two times of secondary eclipse, when the planet passes out of view behind the parent star.   we estimate the relative eclipse depth in 5 distinct bands and find the planet - to - star flux ratio to be @xmath0% ( 3.6 ), @xmath1% ( 4.5 ), @xmath2% ( 5.8 ), @xmath3% ( 8.0 ), and @xmath4% ( 24 ). for consistency, we re - analyze a previously published time series to deduce a contrast ratio in an additional band, @xmath5% ( 16 ).   our data are strongly inconsistent with a planck spectrum, and we clearly detect emission near 4  as predicted by published theoretical models in which this feature arises from a corresponding opacity window. unlike recent results for the exoplanet hd  209458b, we find that the emergent spectrum from hd  189733b is best matched by models that do not include an atmospheric temperature inversion. taken together,   these two studies provide initial observational support for the idea that hot jupiter atmospheres diverge into two classes, in which a thermal inversion layer is present for the more strongly irradiated objects.
the switching model is a markov chain approach to sample graphs with fixed degree sequence uniformly at random.   the recently invented curveball algorithm @xcite for bipartite graphs applies several switches simultaneously ( ` trades'). here, we introduce curveball algorithms for simple ( un)directed graphs which use single or simultaneous trades.   we show experimentally that these algorithms converge magnitudes faster than the corresponding switching models.
we present the differential rates for exclusive @xmath0, where @xmath1 is a charged massless lepton and @xmath2 is a charged or neutral massless lepton, and @xmath3 is a mesonic system up to spin 2.   the cases of interest are semileptonic ( sl ) @xmath4 decays, and @xmath5 where the the di - lepton can be @xmath6 resonances or non - resonant electroweak penguins ( ewp ).   we consider helicity amplitudes having non - zero relative phases that can be potential new sources for cp - violation.   our motivations for these additional phases include a complex right - handed admixture in the hadronic weak charged current for the sl decays and complex wilson coefficients in the effective hamiltonians for the ewp decays.   we demonstrate the efficacy of a novel technique of projecting out the individual angular moments in the full rate expression in a model - independent fashion.   our work is geared towards ongoing data analyses at @xmath7 and lhcb.
the star xo-5  ( gsc 02959 - 00729, v=12.1, g8v ) hosts a jupiter - sized, @xmath0=1.15@xmath10.12  @xmath2, transiting extrasolar planet, xo-5b, with an orbital period of 4.187732@xmath10.00002  days. the planet mass ( @xmath3=1.15@xmath10.08  @xmath4 ) and surface gravity ( @xmath5=22@xmath15 m  s@xmath6 ) are significantly larger than expected by empirical @xmath3-p and @xmath3-p- relationships. however, the deviation from the @xmath3-p relationship for xo-5bis not large enough to suggest a distinct type of planet as is suggested for gj 436b, hat - p-2b, and xo-3b. by coincidence xo-5overlies the extreme h i plume that emanates from the interacting galaxy pair ngc 2444/ngc 2445 ( arp 143 ).
we report the detection of eclipses in gj  3236, a bright ( @xmath0 ) very low mass binary system with an orbital period of @xmath1.   analysis of light- and radial velocity curves of the system yielded component masses of @xmath2 and @xmath3.   the central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present @xmath4 observational uncertainties limit the significance of the larger radii to approximately @xmath5.   degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of gj  3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multi - band photometry covering the full orbital period.   the system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong h@xmath6 emission lines in the spectra of both components.   these observations probe an important region of mass - radius parameter space around the predicted transition to fully - convective stellar interiors, where there are a limited number of precise measurements available in the literature.
we study heat conduction in a one - dimensional chain of particles with longitudinal as well as transverse motions.   the particles are connected by two - dimensional harmonic springs together with bending angle interactions.   the problem is analyzed by mode - coupling theory and compared with molecular dynamics.   we find very good, quantitative agreement for the damping of modes between a full mode - coupling theory and molecular dynamics result, and a simplified mode - coupling theory gives qualitative description of the damping.   the theories predict generically that thermal conductance diverges as @xmath0 as the size @xmath1 increases for systems terminated with heat baths at the ends.   the @xmath2 dependence is also observed in molecular dynamics which we attribute to crossover effect.
the measurements of the fluxes of atmospheric neutrinos give evidence for the disappearance of muon neutrinos.   the determination of the dependence of the disappearance probability on the neutrino energy and trajectory allows in principle to establish unambiguosly the existence of neutrino oscillations.   alternative mechanisms for the disappearance of the neutrinos have been proposed, but do not provide a viable description of the data, if one includes both events where the neutrinos interact in the detector and @xmath0induced upward going muons.   the proposed mechanisms differ in the energy dependence of the disappearance probability and the upward going muon data that are produced by high energy neutrinos give a crucial constraint.   = -0.3 cm = cmr10
the problem of a car following a lead car driven with constant velocity is considered. to derive the governing equations for the following car dynamics a cost functional   is constructed.   this functional ranks the outcomes of different driving strategies, which applies to fairly general properties of the driver behavior. assuming rational driver behavior, the existence of the nash equilibrium is proved.   rational driving is defined by supposing that a driver corrects continuously the car motion to follow the optimal path minimizing the cost functional.   the corresponding car - following dynamics is described quite generally by a boundary value problem based on the obtained extremal equations.   linearization of these equations around the stationary state results in a generalization of the widely used optimal velocity model. under certain conditions ( the `` dense traffic '' limit )   the rational car dynamics comprises two stages, fast and slow. during the fast stage   a driver eliminates the velocity difference between the cars, the subsequent slow stage optimizes the headway. in the `` dense traffic '' limit an effective hamiltonian description   is constructed.   this allows a more detailed nonlinear analysis.   finally, the differences between rational and bounded rational driver behavior are discussed.   the latter, in particular, justifies some basic assumptions used recently by the authors to construct a car - following model lying beyond the frameworks of rationality.
we have compared the tev @xmath0-rays with the new @xmath1co @xmath2=21 data toward hess j1745 - 303 in the galactic center and confirmed that molecular cloud mg358.9 - 0.5 toward @xmath3 at @xmath4@xmath5 km s@xmath6 shows a reasonable positional agreement with the primary peak ( northern part ) of the @xmath0-ray source. for the southern part of hess j1745 - 303  , we see no co counterpart, whereas the h gas in the sgps h dataset shows a possible counterpart to the @xmath0-ray source. this h gas may be optically thick as supported by the h line shape similar to the optically thick @xmath1co.   we estimate the total mass of interstellar protons including both the molecular and atomic gas to be @xmath7 and the cosmic - ray proton energy to be @xmath8 ergs in the hadronic scenario.   we discuss possible origins of the cosmic - ray protons including the nearby snr g359.1 - 0.5. the snr may be able to explain the northern @xmath0-ray source but the southern source seems to be too far to be energized by the snr. as an alternative  , we argue that the second - order fermi acceleration in the inter - clump space surrounded by randomly moving high - velocity clumps may offer a possible mechanism to accelerate protons.   the large turbulent motion with velocity dispersion of @xmath9 km s@xmath6 has energy density two orders of magnitude higher than in the solar vicinity and is viable as the energy source.
we consider a relativistic radiating spherical star in conformally flat spacetimes.   in particular we study the junction condition relating the radial pressure to the heat flux at the boundary of the star which is a nonlinear partial differential equation.   the lie symmetry generators that leave the equation invariant are identified and we generate an optimal system. each element of the optimal system is used to reduce the partial differential equation to an ordinary differential equation which is further analysed.   we identify new categories of exact solutions to the boundary conditions.   two classes of solutions are of interest.   the first class depends on a self similar variable.   the second class is separable in the spacetime variables.
a large class of fractional quantum hall ( fqh ) states can be classified according to their pattern of zeros, which describes the way ideal ground state wave functions go to zero as various clusters of electrons are brought together. in this paper   we generalize this approach to classify multilayer fqh states.   such a classification leads to the construction of a class of non - abelian multilayer fqh states that are closely related to @xmath0 parafermion conformal field theories, where @xmath0 is an affine simple lie algebra.   we discuss the possibility of some of the simplest of these non - abelian states occuring in experiments on bilayer fqh systems at @xmath1, @xmath2, @xmath3, etc.
liquid metal walls in fusion reactors will be subject to instabilities, turbulence, induced currents, error fields and temperature gradients that will make them locally bulge, thus entering in contact with the plasma, or deplete, hence exposing the underlying solid substrate. to prevent this,   research has begun to actively stabilize static or flowing free - surface liquid metal layers by locally applying forces in feedback with thickness measurements. here   we present resistive sensors of liquid metal thickness and demonstrate @xmath0 actuators, to locally control it.   _ keywords _ : liquid metal wall, feedback stabilization, permanent magnet pump
the semiclassical su(3 ) skyrme model is traditionally considered as describing a rigid quantum rotator with the profile function being fixed by the classical solution of the corresponding su(2 ) skyrme model.   in contrast, we go beyond the classical profile function by quantizing the su(3 ) skyrme model canonically.   the quantization of the model is performed in terms of the collective coordinate formalism and leads to the establishment of purely quantum corrections of the model.   these new corrections are of fundamental importance.   they are crucial in obtaining stable quantum solitons of the quantum su(3 ) skyrme model, thus making the model self - consistent and not dependent on the classical solution of the su(2 ) case.   we show that such a treatment of the model leads to a family of stable quantum solitons that describe the baryon octet and decuplet and reproduce their masses in a qualitative agreement with the empirical values.   d. juriukonis@xmath0, e. norvaias@xmath1 and v. regelskis@xmath2 + @xmath3_institute of theoretical physics and astronomy, vilnius university, + gotauto 12, vilnius 01108, lithuania   _ + @xmath4_department of mathematics, university of york, + heslington, york yo10 5dd, uk _
we discuss the relation between the polarization of inclusively produced ( anti- ) + hyperons and the incident baryon states in the framework of the constituent quark - diquark cascade model.   we assume that there is an intrinsic diquark - antidiquark state in the incident baryon, in which the intrinsic diquark immediately fragments into a non - leading baryon and the antidiquark behaves as a valence constituent.   it is also assumed that the valence ( anti)diquark in the incident nucleon tends to combine selectively with a spin - down sea quark and, on the other hand, the spin - up valence quark in the projectile is chosen by a sea ( anti)diquark in preference to the spin - down valence quark.   it is found that the incident spin-1/2 baryon is mainly composed of a spin-0 valence diquark and a valence quark, and contains an intrinsic diquark - antidiquark state with a probability of about 7@xmath0.   + pacs + 13.85.ni(inclusive production with identified hadrons ) + 13.88.+e(polarization in interactions and scattering ) + 14.20.jn(hyperons )    * *   ''' ''    anti - hyperon polarization in @xmath1 and @xmath2 collisions and intrinsic antidiquark state in incident baryon    hujio noda@xmath3, tsutomu tashiro@xmath4 and shin - ichi nakariki@xmath4 + @xmath3department of physics, ibaraki university, mito, ibaraki 310 - 8512, japan + @xmath4resarch institute of natural sciences, okayama university of science, okay
the coherent transport properties of armchair graphene nanoconstrictions(gnc ) are studied using tight - binding approach and green s function method.   we find a non - bonding state at zero fermi energy which results in a zero conductance valley, when a single vacancy locates at @xmath0 of a perfect metallic armchair graphene nanoribbon(agnr ).   however, the non - bonding state does nt exist when a vacancy locates at y=3n, and the conductance behavior of lowest conducting channel will not be affected by the vacancy. for the square - shaped armchair gnc consisting of three metallic agnr segments,   resonant tunneling behavior is observed in the single channel energy region.   we find that the presence of localized edge state locating at the zigzag boundary can affect the resonant tunneling severely.   a simplified one dimensional model is put forward at last, which explains the resonant tunneling behavior of armchair gnc very well.
it is shown that the two - flavor neutrino oscillation equations admit an exact analytic solution for arbitrarily chosen normalized electron neutrino population, provided the electron plasma density is adjusted in a certain way.   the associated formula for the electron plasma density is applied to the cases of exponentially decaying or oscillating electron neutrino populations.
quantum electrodynamics in three dimensions in the bispinor formulation is considered.   it is shown that the dyson - schwinger equations for fermion and boson propagators may be self - consistently solved in the infrared domain if on uses the salam s vertex function.   the parameters defining the behavior of the propagators are found numerically for different values of coupling constant and gauge parameter. for weak coupling   the approximated analytical solutions are obtained.   the renormalized gauge boson propagator ( transverse part ) is shown in the infrared domain to be practically gauge independent.
more than 100 microlensing events have been detected during the last  4 years, most of them towards the galactic bulge. since the line of sight towards the bulge passes through the disk and the bulge itself, the known stars towards the bulge play a dominant role as gravitational lenses.   if these stars have planets around them, then the signature of the planets can be seen as sharp, extra peaks on the microlensing light curves.   frequent, continuous monitoring of the on - going microlensing events thus provides a powerful new method to search for planets around lensing stars.    here   i first review the background on stars acting as gravitational lenses.   i then review the theoretical work on possible observational features due to planets, and the probability of detecting the planets through microlensing.   i then discuss the status / strategy / results of the observational programs currently active in this field.   1.3 cm    0.3 cm
transmitting messages in the most efficient way as possible has always been one of politicians main concerns during electoral processes. due to the rapidly growing number of users,   online social networks have become ideal platforms for politicians to interact with their potential voters.   exploiting the available potential of these tools to maximize their influence over voters is one of politicians actual challenges. to step in this direction  , we have analyzed the user activity in the online social network twitter, during the 2011 spanish presidential electoral process, and found that such activity is correlated with the election results.   we introduce a new measure to study political support in twitter, which we call the relative support.   we have also characterized user behavior by analyzing the structural and dynamical patterns of the complex networks emergent from the mention and retweet networks.   our results suggest that the collective attention is driven by a very small fraction of users.   furthermore we have analyzed the interactions taking place among politicians, observing a lack of debate.   finally we develop a network growth model to reproduce the interactions taking place among politicians.
we classify 329 late - type giants within 1 parsec of sgr a@xmath0, using the adaptive optics integral field spectrometer sinfoni on the vlt.   these observations represent the deepest spectroscopic data set so far obtained for the galactic center, reaching a 50% completeness threshold at the approximate magnitude of the helium - burning red clump ( @xmath1 mag. ). combining our spectroscopic results with naco @xmath2 and @xmath3 photometry  , we construct an observed hertzsprung - russell diagram, which we quantitatively compare to theoretical distributions of various star formation histories of the inner galaxy, using a @xmath4 analysis.   our best - fit model corresponds to continuous star formation over the last 12 gyr with a top - heavy initial mass function ( imf ).   the similarity of this imf to the imf observed for the most recent epoch of star formation is intriguing and perhaps suggests a connection between recent star formation and the stars formed throughout the history of the galactic center.
magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the sun and stars.   nevertheless, such flare - related reconnection is mostly detected to occur in the corona, while there have been few studies concerning the reconnection in the chromosphere or photosphere.   here we present both spectroscopic and imaging observations of magnetic reconnection in the chromosphere leading to a microflare. during the flare peak time, chromospheric line profiles show significant blueshifted / redshifted components on the two sides of the flaring site, corresponding to upflows and downflows with velocities of @xmath0(7080 ) km s@xmath1, comparable with the local alfvn speed as expected by the reconnection in the chromosphere.   the three - dimensional nonlinear force - free field configuration further discloses twisted field lines ( a flux rope ) at a low altitude, cospatial with the dark threads in 10830 images.   the instability of the flux rope may initiate the flare - related reconnection.   these observations provide clear evidence of magnetic reconnection in the chromosphere and show the similar mechanisms of a microflare to those of major flares.
a model for low - energy meson - baryon interaction in the strange sector is presented.   the interaction is described in terms of separable potentials with multiple partial waves considered.   a general solution of lippmann - schwinger equation for the scattering of spin zero and spin one - half particles is derived.   next, the general framework is applied to the @xmath0 sector in a simple model with only the s- and p - waves taken into account.   the separable potential is designed to match the chiral perturbation theory at lowest nontrivial order.   it is shown that although a simple model with three free parameters works well for the s - wave, it fails to reproduce the p - wave features of kaon - nucleon physics.   most importantly, the p - wave interaction is too weak to express a resonant behavior that could be identified as @xmath1 resonance.
in an investigative 16 hour l band observation using the merlin radio interferometric array, we have resolved both the pulsar psr b1951 + 32 and structure within the flat spectral radio continuum region, believed to be the synchrotron nebula associated with the interaction of the pulsar and its ` host'supernova remnant ctb 80.   the extended structure we see, significant at @xmath0 4.5 @xmath1, is of dimensions 2.5 `` @xmath2 0.75 '', and suggests a sharp bow shaped arc of shocked emission, which is correlated with similar structure observed in lower resolution radio maps and x - ray images. using this merlin data as a new astrometric reference for other multiwavelength data we can place the pulsar at one edge of the hst reported optical synchrotron knot, ruling out previous suggested optical counterparts, and allowing an elementary analysis of the optical synchrotron emission which appears to trail the pulsar.   the latter is possibly a consequence of pulsar wind replenishment, and we suggest that the knot is a result of magnetohydrodynamic ( mhd ) instabilities.   these being so, it suggests a dynamical nature to the optical knot, which will require high resolution optical observations to confirm.
this paper proposes a robust control method based on sliding mode design for two - level quantum systems with bounded uncertainties.   an eigenstate of the two - level quantum system is identified as a sliding mode.   the objective is to design a control law to steer the system s state into the sliding mode domain and then maintain it in that domain when bounded uncertainties exist in the system hamiltonian.   we propose a controller design method using the lyapunov methodology and periodic projective measurements.   in particular, we give conditions for designing such a control law, which can guarantee the desired robustness in the presence of the uncertainties.   the sliding mode control method has potential applications to quantum information processing with uncertainties.    quantum control,   sliding mode control, bounded uncertainty, periodic projective measurement, lyapunov methodology.
epitaxially grown quantum dots ( qds ) are promising sources of non - classical states of light such as single photons and entangled photons. however, in order for them to be used as a resource for long - distance quantum communication, distributed quantum computation, or linear optics quantum computing, these photons must be coupled efficiently to long - lived quantum memories as part of a quantum repeater network. here  , we theoretically examine the prospects for efficient storage and retrieval of a qd - generated single photon with a 1  ns lifetime in a multi - level atomic system.   we calculate using an experimentally demonstrated optical depth of 150 that the storage ( total ) efficiency can exceed 46@xmath0 ( 28@xmath0 ) in a dense, ultracold ensemble of @xmath1rb atoms.   furthermore, we find that the optimal control pulse required for storage and retrieval can be obtained using a diode laser and an electro - optic modulator rather than a mode - locked, pulsed laser source.   increasing the optical depth, for example by using bose - condensed ensembles or an optical cavity, can increase the efficiencies to near unity. aside from enabling a high - speed quantum network based on qds, such an efficient optical interface between an atomic ensemble and a qd can also lead to entanglement between collective spin - wave excitations of atoms and the spin of an electron or hole confined in the qd.
successful realization of polarized drell - yan physics program is one of the main goals of the second stage of the compass experiment.   drell - yan measurements with high energy ( 190 gev / c ) pion beam and transversely polarized nh3 target have been initiated by a pilot - run in the october 2014 and will be followed by 140 days of data taking in 2015. in the past twelve years compass experiment   performed series of sidis measurements with high energy muon beam and transversely polarized deuteron and proton targets.   results obtained for sivers effect and other target transverse spin dependent and unpolarized azimuthal asymmetries in sidis serve as an important input for general understanding of spin - structure of the nucleon and are being used in numerous theoretical and phenomenological studies being carried out in the field of transvers - spin physics.   measurement of the sivers and all other azimuthal effects in polarized drell - yan at compass will reveal another side of the spin - puzzle providing a link between sidis and drell - yan branches.   this will be a unique possibility to test universality and key - features of transverse momentum dependent distribution functions ( tmd pdfs ) using essentially same experimental setup and exploring same kinematic domain. in this review main physics aspects of future compass polarized drell - yan measurement of azimuthal transverse spin asymmetries   will be presented, giving a particular emphasis on the link with very recent compass results obtained for sidis transverse spin asymmetries from four `` drell - yan '' @xmath0-ranges.
if the photospheres of solar - type stars represent the composition of circumstellar disks from which any planets formed, spectroscopic determinations of stellar elemental abundances offer information on the composition of those planets, including smaller, rocky planets.   in particular, the c / o ratio is proposed to be a key determinant of the composition of solids that condense from disk gas and are incorporated into planets.   also, planets may leave chemical signatures on the photospheres of their host stars by sequestering heavy elements, or by being accreted by the stars.   the presence, absence, and composition of planets could be revealed by small differences in the relative abundances between stars.   i critically examine these scenarios and show that ( i ) a model of galactic chemical evolution predicts that the c / o ratio is expected to be close to the solar value and vary little between dwarf stars in the solar neighborhood ; ( ii ) spectroscopic surveys of m dwarf stars limit the occurrence of stars with c / o @xmath0 to @xmath1 ; and ( iii ) planetesimal chemistry will be controlled by the composition of oxygen - rich dust inherited from the molecular cloud and processed in a dust - rich environment, not a gas with the stellar composition. a second generation of more reduced planetesimals could be produced by re - equilibration of material with dust - depleted gas.   finally, i discuss how minor differences in relative abundances between stars that correlate with condensation temperature can be explained by dust - gas segregation, perhaps in circumstellar disks, rather than planet formation.
in this paper, we theoretically propose an optomechanical scheme to explore the possibility of simulating the propagation of the collective excitations of the photon fluid in a curved spacetime.   for this purpose, we introduce two theoretical models for two - dimensional photon gas in a planar optomechanical microcavity and a two - dimensional array of coupled optomechanical systems. in the reversed dissipation regime ( rdr ) of cavity optomechanics where the mechanical oscillator reaches equilibrium with its thermal reservoir much faster than the cavity modes, the mechanical degrees of freedom can adiabatically be eliminated.   the adiabatic elimination of the mechanical mode provides an effective nonlinear kerr - type photon - photon interaction. using the nonlinear schrdinger equation ( nlse ),   we show that the phase fluctuations in the two - dimensional photon fluid obey the klein - gordon equation for a massless scalar field propagating in a curved spacetime.   the results reveal that the photon fluid as well as the corresponding metric can be controlled by manipulating the system parameters.
markov random fields provide a compact representation of joint probability distributions by representing its independence properties in an undirected graph.   the well - known hammersley - clifford theorem uses these conditional independences to factorize a gibbs distribution into a set of factors. however, an important issue of using a graph to represent independences is that it can not encode some types of independence relations, such as the context - specific independences ( csis ).   they are a particular case of conditional independences that is true only for a certain assignment of its conditioning set ; in contrast to conditional independences that must hold for all its assignments.   this work presents a method for factorizing a markov random field according to csis present in a distribution, and formally guarantees that this factorization is correct.   this is presented in our main contribution, the context - specific hammersley - clifford theorem, a generalization to csis of the hammersley - clifford theorem that applies for conditional independences.
we study spatiotemporal correlations and temporal diversities of handset - based service usages by analyzing a dataset that includes detailed information about locations and service usages of 124 users over 16 months. by constructing the spatiotemporal trajectories of the users we detect several meaningful places or contexts for each one of them and   show how the context affects the service usage patterns.   we find that temporal patterns of service usages are bound to the typical weekly cycles of humans, yet they show maximal activities at different times.   we first discuss their temporal correlations and then investigate the time - ordering behavior of communication services like calls being followed by the non - communication services like applications.   we also find that the behavioral overlap network based on the clustering of temporal patterns is comparable to the communication network of users.   our approach provides a useful framework for handset - based data analysis and helps us to understand the complexities of information and communications technology enabled human behavior.
five fields located close to the center of the globular cluster ngc  104=47  tuc were surveyed in a search for variable stars.   we present @xmath0-band light curves for 42 variables.   this sample includes 13 rr  lyr stars  12 of them belong to the small magellanic cloud ( smc ) and 1 is a background object from the galactic halo.   twelve eclipsing binaries were identified   9 contact systems and 3 detached / semi - detached systems.   seven eclipsing binaries are located in the blue straggler region on the cluster color - magnitude diagram ( cmd ) and four binaries can be considered main - sequence systems.   one binary is probably a member of the smc.   eight contact binaries are likely members of the cluster and one is most probably a foreground star. we show that for the surveyed region of 47  tuc, the relative frequency of contact binaries is very low as compared with other recently surveyed globular clusters.   the sample of identified variables also includes 15 red variables with periods ranging from about 2 days to several weeks.   a large fraction of these 15 variables probably belong to the smc but a few stars are likely to be red giants in 47  tuc.   @xmath1 photometry for about 50 000 stars from the cluster fields was obtained as a by product of our survey.
an x - ray detector for a solar axion search was developed.   the detector is operated at 60k in a cryostat of a superconducting magnet.   special care was paid to microphonic noise immunity and mechanical structure against thermal contraction.   the detector consists of an array of pin photodiodes and tailor made preamplifiers.   the size of each pin photodiode is @xmath0 and 16 pieces are used for the detector.   the detector consists of two parts, the front - end part being operated at a temperature of 60k and the main part in room temperature. under these circumstances, the detector achieved @xmath1 kev resolution in fwhm,   @xmath2 kev threshold and @xmath3 background level.   axion, helioscope, x - ray, superconducting, pin, photodiode 14.80.mz, 07.85.fv, 29.40.wk
we investigate the origin of the scaling corrections in ballistic deposition models in high dimensions using the method proposed by alves _   et al_. [ phys rev.   e * 90 *, 052405 ( 20014 ) ] in @xmath0 dimensions, where the intrinsic width associated with the fluctuations of the height increments during the deposition processes is explicitly taken into account. in the present work,   we show that this concept holds for @xmath1 and 4 + 1 dimensions.   we have found that growth and roughness exponents and dimensionless cumulant ratios are in agreement with other models, presenting small finite - time corrections to the scaling, that in principle belong to he kardar - parisi - zhang ( kpz ) universality class in both @xmath1 and 4 + 1.   our results constitute a new evidence that the upper critical dimension of the kpz class, if it exists, is larger than 4.
the capacity to resist attacks from the environment is crucial to the survival of all organisms.   we quantitatively analyze the susceptibility of protein interaction networks of numerous organisms to random and malicious attacks.   we find for all organisms studied that random rewiring improves protein network robustness, so that actual networks are more fragile than rewired surrogates.   this unexpected fragility contrasts with the behavior of networks such as the internet, whose robustness decreases with random rewiring.   we trace this surprising effect to the modular structure of protein networks.
this article describes the fluid dynamics video, `` a numerical simulation of a plunging breaking wave '', which was submitted to the gallery of fluid motion at the 2009 aps / dfd conference.   the simulation was of a deep - water plunging breaking wave.   it was a two - phase calculation which used a volume of fluid ( vof ) method to simulate the interface between the two immiscible fluids.   surface tension and viscous effects were not considered.   the initial wave was generated by applying a spatio - temporal pressure forcing on the free surface.   the video shows the 50% isocontour of the volume fraction from several different perspectives.   significant air entrainment is observed as well as the presence of stream - wise vortex structures.
we present the results of the observations of the ly@xmath0 line profiles of 91 emission - line galaxies at @xmath1 with the spectral resolution of @xmath2/@xmath3(fwhm ) @xmath4, or 180 km s@xmath5.   a significant fraction, @xmath6@xmath7 of the observed objects show the characteristic double peaks in their ly@xmath0 profile.   the red peak is much stronger than the blue one for most of the cases.   the red peaks themselves also show weak but significant asymmetry and their widths are correlated with the velocity separation of the red and the blue peaks, which implies that the peaks are not isolated multiple components with different velocities but the parts of the single line which is modified by the absorption and/or scattering by the associated neutral hydrogen gas.   the characteristic profile can be naturally explained by the scattering in the expanding shell of neutral hydrogen surrounding the ly@xmath0 emitting region while the attenuation by the inter - galactic medium should also be considered.   our results suggest that the star - formation in these ly@xmath0 emitters are dominated by the young burst - like events which produce the intrinsic ly@xmath0 emission as well as the gas outflow.
an implementation of quantum absorption chillers with three qubits has been recently proposed, that is ideally able to reach the carnot performance regime. here   we study the working efficiency of such self - contained refrigerators, adopting a consistent treatment of dissipation effects.   we demonstrate that the coefficient of performance at maximum cooling power is upper bounded by @xmath0 of the carnot performance.   the result is independent of the details of the system and the equilibrium temperatures of the external baths.   we provide design prescriptions that saturate the bound in the limit of a large difference between the operating temperatures.   our study suggests that delocalized dissipation, which must be taken into account for a proper modelling of the machine - baths interaction, is a fundamental source of irreversibility which prevents the refrigerator from approaching the carnot performance arbitrarily closely in practice.   the potential role of quantum correlations in the operation of these machines is also investigated.
the first molecules detected at infrared wavelengths in the ejecta of a type ii supernova, namely sn1987a, consisted of co and sio. since then, confirmation of the formation of these two species in several other supernovae a few hundred days after explosion has been obtained. however, supernova environments appear to hamper the synthesis of large, complex species due to the lack of microscopically - mixed hydrogen deep in supernova cores. because these environments also form carbon and silicate dust, it is of importance to understand the role played by molecules in the depletion of elements and how chemical species get incorporated into dust grains. in the present paper,   we review our current knowledge of the molecular component of supernova ejecta, and present new trends and results on the synthesis of molecules in these harsh, explosive events.
we performed density functional studies of electronic properties and mechanisms of hydrogen transport in rb@xmath0h(seo@xmath1)@xmath2 crystal which represents technologically promising class m@xmath0h(xo@xmath1)@xmath2 of proton conductors ( m = rb, cs, nh4 ; x = s, se ).   the electronic structure calculations show a decisive role of lattice dynamics in the process of proton migration. in the obtained revised mechanism of proton transport,   the strong displacements of the vertex oxygens play a key role in the establishing the continuous hydrogen transport and in the achieving low activation energies of proton conduction which is in contrast to the standard two - stage grotthuss mechanism of proton transport.   consequently, any realistic model description of proton transport should inevitably involve the interactions with the sublattice of the xo@xmath1 groups.
the performance of telescope systems working at microwave or visible / ir wavelengths is typically described in terms of different parameters according to the wavelength range.   most commercial ray tracing packages have been specifically designed for use with visible / ir systems and thus, though very flexible and sophisticated, do not provide the appropriate parameters to fully describe microwave antennas, and thus to compare with specifications. in this work   we demonstrate that the strehl ratio is equal to the phase efficiency when the apodization factor is taken into account.   the phase efficiency is the most critical contribution to the aperture efficiency of an antenna, and the most difficult parameter to optimize during the telescope design.   the equivalence between the strehl ratio and the phase efficiency gives the designer / user of the telescope the opportunity to use the faster commercial ray - tracing software to optimize the design.   we also discuss the results of several tests performed to check the validity of this relationship that we carried out using a ray - tracing software, zemax and a full physical optics software, grasp9.3, applied to three different telescope designs that span a factor of @xmath0 in terms of @xmath1.   the maximum measured discrepancy between phase efficiency and strehl ratio varies between @xmath2% and 1.9% up to an offset angle of @xmath3 beams, depending on the optical configuration, but it is always less than 0.5% where the strehl ratio is @xmath4.
using dark matter halos traced by galaxy groups selected from the sloan digital sky survey data release 4, we find that about 1/4 of the faint galaxies ( @xmath0, hereafter dwarfs ) that are the central galaxies in their own halo are not blue and star forming, as expected in standard models of galaxy formation, but are red.   in contrast, this fraction is about 1/2 for dwarf satellite galaxies.   many red dwarf galaxies are physically associated with more massive halos. in total, about @xmath1% of red dwarf galaxies reside in massive halos as satellites, while another @xmath2% have a spatial distribution that is much more concentrated towards their nearest massive haloes than other dwarf galaxies.   we use mock catalogs to show that the reddest population of non - satellite dwarf galaxies are distributed within about 3 times the virial radii of their nearest massive halos.   we suggest that this population of dwarf galaxies are hosted by low - mass halos that have passed through their massive neighbors, and that the same environmental effects that cause satellite galaxies to become red are also responsible for the red colors of this population of galaxies.   we do not find any significant radial dependence of the population of dwarf galaxies with the highest concentrations, suggesting that the mechanisms operating on these galaxies affect color more than structure.   however, over 30% of dwarf galaxies are red and isolated and their origin remains unknown.
first attempts are made to derive astrophysical implications of the collision of clumped stellar winds from order of magnitude estimates and preliminary numerical simulations.   compared to colliding smooth winds, we find that the most significant differences occur in widely separated systems like wr  140.   clumped winds de - stabilize the wind - wind interaction zone of such systems.   highly compressed, cold knots of wr - wind material can form.   hydrogen rich material is likely to be mixed into these knots by the excited turbulence.   such knots, therefore, are good candidates to form dust.   we briefly discuss to what degree our results can be applied to other systems and look at different possibilities for the origin and nature of the inhomogeneities in hot star winds.
the production of fast neutrons ( 1 mev - 1 gev ) in high energy muon - nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments.   the aim of the present experiment ( cern na55 ) was to measure spallation neutrons produced by 190 gev / c muons scattering on carbon, copper and lead targets.   we have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross section.   ,   ,   ,   ,   ,   ,   ,   ,    underground neutron flux, fast neutron production, muon - nucleus interaction, time - of - flight 25.30.mr, 25.20.-x, 25.40.sc, 28.20.-v
we study the possibility for the process @xmath0 with anomalous wtb couplings in a model independent effective lagrangian approach at the lhc.   we find @xmath1 confidence level bounds on the anomalous coupling parameters for various values of the integrated luminosity.   the improved constraints on the anomalous wtb couplings have been obtained compared to current limits.
we analyze a legendre invariant metric structure in the space of thermodynamic equilibrium states of an ideal gas.   due to the lack of thermodynamic interaction, the geometry turns out to be flat.   we introduce the concept of thermodynamic geodesics, which correspond to quasi - static processes, analyze their properties, and show that they can be used to determine the  arrow of time " and to split the equilibrium space of the ideal gas into two completely different regions, separated by adiabatic geodesics which correspond to reversible thermodynamic processes.
astrometric observations of the radio source occultations by solar system bodies may be of large interest for testing gravity theories, dynamical astronomy, and planetary physics. in this paper, we present an updated list of the occultations of astrometric radio sources by planets expected in the nearest years. such events, like the solar eclipses, generally speaking, can be only observed in a limited region.   the map of the shadow path is provided for the events occurred in regions with several vlbi stations and hence the most interesting for radio astronomy experiments.
an alternative being considered for the next linear collider ( nlc ) is not to tunnel in a straight line but to bend the main linac into an arc so as to follow an equipotential.   we begin here an examination of the effects that this would have on vertical dispersion, with its attendant consequences on synchrotron radiation and emittance growth by looking at two scenarios : a gentle continuous bending of the beam to follow an equipotential surface, and an introduction of sharp bends at a few sites in the linac so as to reduce the maximum sagitta produced.
in a recent article [ m. merolle et al., proc.   natl. acad.   sci.   usa 102, 10837 ( 2005 ) ], it was argued that dynamic heterogeneity in @xmath0-dimensional glass formers is a manifestation of an order - disorder phenomenon in the @xmath1 dimensions of space - time. by considering a dynamical analogue of the free energy,   evidence was found for phase coexistence between active and inactive regions of space - time, and it was suggested that this phenomenon underlies the glass transition.   here we develop these ideas further by investigating in detail the one - dimensional fredrickson - andersen ( fa ) model in which the active and inactive phases originate in the reducibility of the dynamics.   we illustrate the phase coexistence by considering the distributions of mesoscopic space - time observables.   we show how the analogy with phase coexistence can be strengthened by breaking microscopic reversibility in the fa model, leading to a non - equilibrium theory in the directed percolation universality class.
using the westerbork synthesis radio telescope, we have detected hi 21 cm - line absorption in the warm neutral medium of the galaxy toward the extragalactic source 3c147.   this absorption, at an lsr velocity of 29@xmath04 km s@xmath1 with a full width at half maximum of 53@xmath06 km s@xmath1, is associated with the perseus arm of the galaxy.   the observed optical depth is ( 1.9@xmath00.2)@xmath210@xmath3.   the estimated spin temperature of the gas is 3600@xmath0360 k. the volume density is 0.4 cm@xmath3 assuming pressure equilibrium. toward two other sources, 3c273 and 3c295, no wide hi 21 cm - line absorption was detected.   the highest of the 3@xmath5 lower limits on the spin temperature of the warm neutral medium is 2600 k. in addition, we have also detected hi 21 cm - line absorption from high velocity clouds in the outer arm toward 3c147 and 3c380 at lsr velocities of 117.3, 124.5 and 113.7 km s@xmath1 respectively.   we find two distinct temperature components in the high velocity clouds with spin temperatures of greater than 1000 k and less than 200 k, respectively.
we present a geometric study of the radio and @xmath0-ray pulsar b105552 based on recent observations at the parkes radio telescope.   we conclude that the pulsar s magnetic axis is inclined at an angle of @xmath1 to its rotation axis and that both its radio main pulse and interpulse are emitted at the same height above their respective poles.   this height is unlikely to be higher or much lower than 700 km, a typical value for radio pulsars.   it is argued that the radio interpulse arises from emission formed on open fieldlines close to the magnetic axis which do not pass through the magnetosphere s null ( zero - charge ) surface.   however the main pulse emission must originate from fieldlines lying well outside the polar cap boundary beyond the null surface, and farther away from the magnetic axis than those of the outergap region where the single @xmath0-ray peak is generated.   this casts doubt on the common assumption that all pulsars have closed, quiescent, corotating regions stretching to the light cylinder.       pulsars : general, individual(b105552 )  polarization  radiation mechanisms : non - thermal  plasmas  mhd
we have used a model of magnetic accretion to investigate the rotational equilibria of magnetic cataclysmic variables ( mcvs ).   this has enabled us to derive a set of equilibrium spin periods as a function of orbital period and magnetic moment which we use to estimate the magnetic moments of all known intermediate polars.   we further show how these equilibrium spin periods relate to the polar synchronisation condition and use these results to calculate the theoretical histogram describing the distribution of magnetic cvs as a function of @xmath0.   we demonstrate that this is in remarkable agreement with the observed distribution assuming that the number of systems as a function of white dwarf magnetic moment is distributed according to @xmath1.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present an abundance analysis of eight potential member stars of the old galactic bulge globular cluster ngc6522.   the same stars have previously been studied by @xcite, who found very high abundances of the slow neutron capture elements compared with other clusters and field stars of similar metallicity, which they interpreted as reflecting nucleosynthesis in rapidly rotating, massive population iii stars.   in contrast to their analysis, we do not find any unusual enhancements of the neutron capture elements sr, y, ba and eu and conclude that previous claims result mainly from not properly accounting for blending lines.   instead we find ngc6522 to be an unremarkable globular cluster with comparable abundance trends to other galactic globular clusters at the same metallicity ( @xmath0}=-1.15\pm0.16 $ ] ).   the stars are also chemically similar to halo and bulge field stars at the same metallicity, spanning a small range in  and with normal @xmath1-element abundances.   we thus find no observational evidence for any chemical signatures of rapidly rotating population iii stars in ngc6522.       stars
the functional method to derive the fractional fokker - planck equation for probability distribution from the langevin equation with lvy stable noise is proposed. for the cauchy stable noise   we obtain the exact stationary probability density function of lvy flights in different smooth potential profiles.   we find confinement of the particle in the superdiffusion motion with a bimodal stationary distribution for all the anharmonic symmetric monostable potentials investigated.   the stationary probability density functions show power - law tails, which ensure finiteness of the variance. by reviewing recent results on these statistical characteristics, the peculiarities of lvy flights in comparison with ordinary brownian motion   are discussed.
i have discussed in my talk several remaining issues in the standard three - flavor mixing scheme of neutrinos, in particilar, the sign of @xmath0 and the leptonic cp violating phase. in this report   i focus on two topics : ( 1 ) supernova method for determining the former sign, and ( 2 ) illuminating how one can detect the signatures for both of them in long - baseline ( @xmath1 km ) neutrino oscillation experiments.   i do this by formulating perturbative frameworks appropriate for the two typical options of such experiments, the high energy and the low energy options with beam energies of @xmath2 10 gev and @xmath2 100 mev, respectively.
we measure quantum and thermal phase - slip rates using the standard deviation of the switching current in superconducting nanowires.   our rigorous quantitative analysis provides firm evidence for the presence of quantum phase slips ( qpss ) in homogeneous nanowires at high bias currents.   we observe that as temperature is lowered, thermal fluctuations freeze at a characteristic crossover temperature @xmath0, below which the dispersion of the switching current saturates to a constant value, indicating the presence of qpss. the scaling of the crossover temperature @xmath0 with the critical temperature @xmath1 is linear, @xmath2, which is consistent with the theory of macroscopic quantum tunneling.   we can convert the wires from the initial amorphous phase to a single - crystal phase, _ in situ _  , by applying calibrated voltage pulses.   this technique allows us to probe directly the effects of the wire resistance, critical temperature, and morphology on thermal and quantum phase slips.
the multiple timescale dynamics induced by radiation pressure and photothermal effects in a high - finesse optomechanical resonator is experimentally studied. at difference with 2d slow - fast systems,   the transition from the quasi - harmonic to the relaxational regime occurs via chaotic canard explosions, where large- amplitude relaxation spikes are separated by an irregular number of subthreshold oscillations.   we also show that this regime coexists with other periodic attractors, on which the trajectories evolve on a substantially faster time - scale.   the experimental results are reproduced and analyzed by means of a detailed physical model of our system.
this paper introduces a general theoretical framework to analyze noise limited networks.   more precisely, we consider two homogenous poisson point processes of base stations and users.   general model of radio signal propagation and effect of fading are also considered.   the main difference of our model with respect to other existing models is that a user connects to his best servers but not necessarily the closest one.   we provide general formula for the outage probability.   we study functionals related to the snr as well as the sum of these functionals over all users per cell. for the latter, the expectation and bounds on the variance are obtained.   lemma    proposition
black branes are studied in einstein - gauss - bonnet ( egb ) gravity.   evaporation drives black branes towards one of two singularities depending on the sign of @xmath0, the gauss - bonnet coupling. for positive @xmath0 and sufficiently large ratio @xmath1, where @xmath2 is the radius of compactification, black branes avoid the gregory - laflamme ( gl ) instability before reaching a critical state.   no black branes with the radius of horizon smaller than the critical value can exist. approaching the critical state branes have a nonzero hawking temperature. for negative @xmath0   all black branes encounter the gl instability.   no black branes may exist outside of the interval of the critical values, @xmath3, where @xmath4 and @xmath5 is the radius of horizon of the black brane.   the first order phase transition line of gl transitions ends in a second order phase transition point at @xmath6.
the tokai  to  kamioka ( t2k ) experiment is a second generation long baseline neutrino oscillation experiment which aims at a sensitive search for the @xmath0 appearance.   the main design features of the t2k near neutrino detectors located at 280 m from the target are presented.   scintillator counters developed for the t2k near detectors are described.   readout of the counters is provided via wls fibers embedded into s   shape grooves in a scintillator and viewed from both ends by multi   pixel avalanche photodiodes operating in a limited geiger mode. a description, operational principles and the results of tests of photosensors with a sensitive area of 1.1 mm@xmath1 are presented.   a time resolution of 1.5 ns, a spatial resolution of 9.912.4 cm, and a mip detection efficiency of more than 99% were obtained for scintillator detectors in a beam test.
a steepening feature in the outer density profiles of dark matter halos indicating the splashback radius has drawn much attention recently.   possible observational detections have even been made for galaxy clusters.   theoretically, adhikari et al.   have estimated the location of the splashback radius by computing the secondary infall trajectory of a dark matter shell through a growing dark matter halo with an nfw profile. however, since they imposed a shape of the halo profile rather than computing it consistently from the trajectories of the dark matter shells, they could not provide the full shape of the dark matter profile around the splashback radius.   we improve on this by extending the self - similar spherical collapse model of fillmore & goldreich to a @xmath0cdm universe.   this allows us to compute the dark matter halo profile and the trajectories simultaneously from the mass accretion history.   our results on the splashback location agree qualitatively with adhikari et al.   but with small quantitative differences at large mass accretion rates.   we present new fitting formulae for the splashback radius @xmath1 in various forms, including the ratios of @xmath2 and @xmath3.   numerical simulations have made the puzzling discovery that the splashback radius scales well with @xmath4 but not with @xmath5.   we trace the origin of this to be the correlated increase of @xmath6 and the average halo mass accretion rate with an increasing redshift.       cosmology : theory  dark matter  methods : analytical  galaxies : clusters : general
we present a new general mechanism to generate curvature perturbations after the end of the slow - roll phase of inflation.   our model is based on the simple assumption that the potential driving inflation is characterized by an underlying global symmetry which is slightly broken.
there are several models for generating fluctuations in an open universe that are compatible with the microwave background fluctuations detected by cobe _ and _ observations of large scale structure.   topological defects, such as strings and textures, appear to be more successful in a low-@xmath0 model than in an @xmath1 model.   these models predict that the cosmic microwave background ( cmb ) fluctuations are non - gaussian with distinctive signatures that may lead to their confirmation. if there exists a mechanism for generating scale invariant mass fluctuations, @xmath2, then these models are also compatible with cobe.   both models predict mass fluctuations on the 8/h mpc scale, @xmath3, @xmath4 for @xmath5.   a variety of observations of large - scale structure, clusters and galaxies, as well as the age problem, suggest that the low-@xmath0 models are attractive.
we develop the synchronization theory of microwave induced zero - resistance states ( zrs ) for two - dimensional electron gas in a magnetic field. in this theory   the dissipative effects lead to synchronization of cyclotron phase with driving microwave phase at certain resonant ratios between microwave and cyclotron frequencies.   this synchronization produces stabilization of electron transport along edge channels and at the same time it gives suppression of dissipative scattering on local impurities and dissipative conductivity in the bulk, thus creating the zrs phases at that frequency ratios.   the electron dynamics along edge and around circular disk impurity is well described by the chirikov standard map.   the theoretical analysis is based on extensive numerical simulations of classical electron transport in a strongly nonlinear regime.   we also discuss the value of activation energy obtained in our model and the experimental signatures that could establish the synchronization origin of zrs.
we study the bijection between binary galton  watson trees in continuous time and their exploration process, both in the sub- and in the supercritical cases.   we then take the limit over renormalized quantities, as the size of the population tends to infinity.   we thus deduce delmas generalization of the second ray  knight theorem.
the relationships between braid ordering and the geometry of its closure is studied.   we prove that if an essential closed surface @xmath0 in the complements of closed braid has relatively small genus with respect to the dehornoy floor of the braid, @xmath0 is circular - foliated in a sense of birman - menasco s braid foliation theory. as an application of the result, we prove that if dehornoy floor of braids are larger than three, nielsen - thurston classification of braids and the geometry of their closure s complements are in one - to - one correspondence. using this result, we construct infinitely many hyperbolic knots explicitly from pseudo - anosov element of mapping class groups.
we investigate the dynamics of bloch electrons using a density operator method and connect this approach with previous theories based on wave packets.   we study non - interacting systems with negligible disorder and strong spin - orbit interactions, which have been at the forefront of recent research on spin - related phenomena.   we demonstrate that the requirement of gauge invariance results in a shift in the position at which the wigner function of bloch electrons is evaluated.   the present formalism also yields the correction to the carrier velocity arising from the berry phase.   the gauge - dependent shift in carrier position and the berry phase correction to the carrier velocity naturally appear in the charge and current density distributions. in the context of spin transport   we show that the spin velocity may be defined in such a way as to enable spin dynamics to be treated on the same footing as charge dynamics. aside from the gauge - dependent position shift we find additional, gauge - covariant multipole terms in the density distributions of spin, spin current and spin torque.
this talk discusses the prospects for supersymmetry studies at the lhc and nlc.   the results are based on those of the supersymmetry working group at the 1996 snowmass workshop.   = 11    versim#1#2 # 1  = 12 epsf # 1 # 1    # 1 - 1pt2.5pt
we calculate correlation functions of the energy - momentum tensor in the vicinity of the deconfinement phase transition of ( 3 + 1)-dimensional su(2 ) gauge theory and discuss their critical behavior in the vicinity of the second order deconfinement transition.   we show that correlation functions of the trace of the energy momentum tensor diverge uniformly at the critical point in proportion to the specific heat singularity.   correlation functions of the pressure, on the other hand, stay finite at the critical point.   we discuss the consequences of these findings for the analysis of transport coefficients, in particular the bulk viscosity, in the vicinity of a second order phase transition point.
the effects of boundary impurities on the entanglement entropy in an antiferromagnetic heisenberg opened spin-@xmath0 chain are investigated.   the method of density - matrix renormalization - group is used to obtain the bipartite entanglement.   the entropy increases when the length of the subsystem increases  . it will approach to a constant when system length is very large. with the same impurity interaction, qutrit impurities of spin-@xmath1   can increase the entanglement entropy.    * pacs numbers : * 03.67.mn, 03.65.ud, 05.50.+q, 75.10.jm    * key words : * entropy, boundary impurities, dmrg
we present the first dynamical mass measurements for lyman-@xmath0  galaxies at high redshift, based on velocity dispersion measurements from rest - frame optical emission lines and size measurements from hst imaging, for a sample of nine galaxies drawn from four surveys.   these measurements enable us to study the nature of lyman-@xmath0  galaxies in the context of galaxy scaling relations.   the resulting dynamical masses range from @xmath1 to @xmath2.   we also fit stellar population models to our sample, and use them to plot the lyman-@xmath0  sample on a stellar mass vs. line width relation.   overall, the lyman-@xmath0  galaxies follow well the scaling relation established by observing star forming galaxies at lower redshift ( and without regard for lyman-@xmath0  emission ), though in @xmath3 of the lyman-@xmath0  galaxies, lower - mass fits are also acceptable. in all cases,   the _ dynamical _ masses agree with established _ stellar _ mass - linewidth relation. using the dynamical masses as an upper limit on gas mass  , we show that lyman-@xmath0  galaxies resemble starbursts ( rather than `` normal '' galaxies ) in the relation between gas mass surface density and star formation activity, in spite of relatively modest star formation rates.   finally, we examine the mass densities of these galaxies, and show that their future evolution likely requires dissipational ( `` wet '' ) merging. in short, we find that lyman-@xmath0  galaxies are low mass cousins of larger starbursts.   17f_17    2s @xmath4 43l_43
we present a chronological review of the progress in calculating weak matrix elements using staggered fermions.   we review the perturbative calculation of one - loop matching formula including both current - current diagrams and penguin diagrams using improved staggered fermions.   we also present preliminary results of weak matrix elements relevant to cp violation calculated using the improved ( hyp ( ii ) ) staggered fermions.   since the complete set of matching coefficients at the one - loop level became available recently, we have constructed lattice operators with all the @xmath0 corrections included.   the main results include both @xmath1 and @xmath2 contributions.
we present simultaneous multi - color optical photometry using ultracam of the transiting exoplanet kic12557548b ( also known as kic1255b ).   this reveals, for the first time, the color dependence of the transit depth.   our @xmath0 and @xmath1 transits are similar in shape to the average _ kepler _ short - cadence profile, and constitute the highest - quality extant coverage of _ individual _ transits. our night 1   transit depths are @xmath2 in @xmath1 ; @xmath3 in @xmath0 ; and @xmath4 in @xmath5. we employ a residual - permutation method to assess the impact of correlated noise on the depth difference between the @xmath1 and @xmath0 bands and calculate the significance of the color dependence at @xmath6.   the night 1 depths are consistent with dust extinction as observed in the ism, but require grain sizes comparable to the largest found in the ism : 0.251@xmath7 m.   this provides direct evidence in favor of this object being a disrupting low - mass rocky planet, feeding a transiting dust cloud. on the remaining four nights of observations the object was in a rare shallow - transit phase. if the grain size in the transiting dust cloud changes as the transit depth changes  , the extinction efficiency is expected to change in a wavelength- and composition - dependent way.   observing a change in the wavelength - dependent transit depth would offer an unprecedented opportunity to determine the composition of the disintegrating rocky body kic12557548b.   we detected four out - of - transit @xmath5 band events consistent with stellar flares.
the magnetization of neutron star matter in magnetic fields is studied by employing the fsugold interaction.   it is found that the magnetic susceptibilities of the charged particles ( proton, electron and muon ) can be larger than that of neutron.   the effects of the anomalous magnetic moments ( amm ) of each component on the magnetic susceptibility are examined in detail.   it is found that the proton and electron amm affect their respective magnetic susceptibility evidently in strong magnetic fields.   in addition, they are the protons instead of the electrons that contribute most significantly to the magnetization of the neutron star matter in a relative weak magnetic field, and the induced magnetic field due to the magnetization can be appear to be very large.   finally, the effect of the density - dependent symmetry energy on the magnetization is discussed.   gbk song
we consider a basic quantum hybrid network model consisting of a number of nodes each holding a qubit, for which the aim is to drive the network to a consensus in the sense that all qubits reach a common state.   projective measurements are applied serving as control means, and the measurement results are exchanged among the nodes via classical communication channels.   we show how to carry out centralized optimal path planning for this network with all - to - all classical communications, in which case the problem becomes a stochastic optimal control problem with a continuous action space. to overcome the computation and communication obstacles facing the centralized solutions  , we also develop a distributed pairwise qubit projection ( pqp ) algorithm, where pairs of nodes meet at a given time and respectively perform measurements at their geometric average.   we show that the qubit states are driven to a consensus almost surely along the proposed pqp algorithm, and that the expected qubit density operators converge to the average of the network s initial values.
culinary systems, the practice of preparing a refined combination of ingredients that is palatable as well as socially acceptable, are examples of complex dynamical systems.   they evolve over time and are affected by a large number of factors.   modeling the dynamic nature of evolution of regional cuisines may provide us a quantitative basis and exhibit underlying processes that have driven them into the present day status.   this is especially important given that the potential culinary space is practically infinite because of possible number of ingredient combinations as recipes.   such studies also provide a means to compare and contrast cuisines and to unearth their therapeutic value.   herein we provide rigorous analysis of modeling eight diverse indian regional cuisines, while also highlighting their uniqueness, and a comparison among those models at the level of flavor compounds which opens up molecular level studies associating them especially with non - communicable diseases such as diabetes.   pacs numbers : :    89.75.-k, 82.20.wt, 87.18.vf, 87.10.vg, 89.90.+n
motivated by a proposal of daykin @xcite, we study the wave that propagates along an infinite chain of dominoes and find the limiting speed of the wave in an extreme case. +   * keywords * : dominoes, waves, modelling, mechanics + * ams subject classification * : 70b99, 70f35, 97a90 + * doi * : 10.1137/s0036144504414505
two fortran programs are presented which plot the hertzsprung - russell diagram and the temporal evolution of such stellar quantities as : central and photospheric isotopic abundances, central densities and temperatures, luminosities, effective temperatures and photospheric radii for a wide range of stellar masses.   the programs, which are modifications and extensions of some modules of the _ tycho 6.0 _ stellar evolution package, are accompanied by various control input files as well as by a library of data.   the data library is actually one of the output files generated by _ tycho 7.0 _ ( a modified version of _ tycho 6.0 _ ), while the plots themselves are generated by the pgplot graphics subroutine library which is also publicly available and well cited  .    -0.25 cm -0.25 cm -1.0 cm 16.3 cm 22.3 cm
motivated by recent dna - pulling experiments, we revisit the poland - scheraga model of melting a double - stranded polymer.   we include distinct bending rigidities for both the double - stranded segments, and the single - stranded segments forming a bubble.   there is also bending stiffness at the branch points between the two segment types.   the transfer matrix technique for single persistent chains is generalized to describe the branching bubbles.   properties of spherical harmonics are then exploited in truncating and numerically solving the resulting transfer matrix.   this allows efficient computation of phase diagrams and force - extension curves ( isotherms ).   while the main focus is on exposition of the transfer matrix technique, we provide general arguments for a reentrant melting transition in stiff double strands.   our theoretical approach can also be extended to study polymers with bubbles of any number of strands, with potential applications to molecules such as collagen.
we compute spectra from accretion disks around rapidly rotating neutron stars.   the full effect of general relativity is considered for the structure calculation of the stars.   we take into account the doppler shift, gravitational redshift and light - bending effects in order to compute the observed spectra. to facilitate direct comparison with observations,   a simple empirical function is presented which describes the numerically computed spectra well.   this function can in principle be used to distinguish between the newtonian spectra and the relativistic spectra.   we also discuss the possibility of constraining neutron star s equation of state using our spectral models.   # 1 1.25 in.125 in.25 in
a large - scale gradient in the metal abundance has been detected with  from an x - ray bright cluster of galaxies awm7.   the metal abundance shows a peak of 0.5 solar at the center and smoothly declines to @xmath0 solar at a radius of 500 kpc.   the gas temperature is found to be constant at 3.8 kev.   the radial distribution of iron can be fit with a @xmath1-model with @xmath2 assuming the same core radius ( 115 kpc ) as that of the intracluster medium.   the metal distribution in awm7 suggests that the gas injected from galaxies is not efficiently mixed in the cluster space and traces the distribution of galaxies.
we evaluate exactly the non - markovian effect on the decoherence dynamics of a qubit interacting with a dissipative vacuum reservoir and find that the coherence of the qubit can be partially trapped in the steady state when the memory effect of the reservoir is considered.   our analysis shows that it is the formation of a bound state between the qubit and its reservoir that results in this residual coherence in the steady state under the non - markovian dynamics. a physical condition for the decoherence suppression   is given explicitly.   our results suggest a potential way to decoherence control by modifying the system - reservoir interaction and the spectrum of the reservoir to the non - markovian regime in the scenario of reservoir engineering.
the mass shift, width broadening, and spectral density for the @xmath0 and @xmath1 mesons in a heat bath of nucleons and pions are calculated using a general formula which relates the self - energy to the real and imaginary parts of the forward scattering amplitude.   we use experimental data to saturate the scattering amplitude at low energies with resonances and include a background pomeron term, while at high energies a regge parameterization is used. the real part obtained   directly is compared with the result of a dispersion integral over the imaginary part.   the peaks of the spectral densities are little shifted from their vacuum positions, but the widths are considerably increased due to collisional broadening. where possible we compare with the urqmd model and find quite good agreement.   at normal nuclear matter density and a temperature of 150 mev the spectral density of the @xmath0 meson has a width of 345 mev, while that for the @xmath1 is in the range 90150 mev.
a novel formalism for bayesian learning in the context of complex inference models is proposed.   the method is based on the use of the stationary fokker  planck ( sfp ) approach to sample from the posterior density.   stationary fokker   planck sampling generalizes the gibbs sampler algorithm for arbitrary and unknown conditional densities. by the sfp procedure approximate analytical expressions for the conditionals and marginals of the posterior   can be constructed. at each stage of sfp,   the approximate conditionals are used to define a gibbs sampling process, which is convergent to the full joint posterior. by the analytical marginals   efficient learning methods in the context of artificial neural networks are outlined. off   line and incremental bayesian inference and maximum likelihood estimation from the posterior is performed in classification and regression examples.   a comparison of sfp with other monte carlo strategies in the general problem of sampling from arbitrary densities is also presented.   it is shown that sfp is able to jump large low  probabilty regions without the need of a careful tuning of any step size parameter.   in fact, the sfp method requires only a small set of meaningful parameters which can be selected following clear, problem  independent guidelines.   the computation cost of sfp, measured in terms of loss function evaluations, grows linearly with the given model s dimension.
in this paper we study the concurrence and the block - block entanglement in the @xmath0 spin ladder with four - spin ring exchange by the exact diagonalization method of finite cluster of spins.   the relationship between the global phase diagram and the ground - state entanglement is investigated.   it is shown that the block - block entanglement of different block size and geometry manifests richer information of the system.   we find that the extremal point of the two - site block - block entanglement on the rung locates a transition point exactly due to @xmath1 symmetry at this point.   the scaling behavior of the block - block entanglement is discussed.   our results suggest that the block - block entanglement can be used as a convenient marker of quantum phase transition in some complex spin systems.
we introduce a generalization of @xmath0 dimensional large @xmath1 qcd, which we refer to as `` reduced '' qcd, or rqcd. in this   model gluons and quark momenta live in @xmath0 dimensions only, but the quark spin and all other particles ( leptons, and the photon ) live in the full @xmath2 dimensions.   the bound states of quarks and antiquarks are identical to those originally described by t hooft ( except that there are new transversely polarized states previously excluded ), so the model is exactly soluable.   however, significant differences arise when the model is applied to electromagnetic interactions. after reviewing the strongly interacting sector of the theory  , we discuss deep inelastic scattering ( dis ) in this model, and show that the new states with transverse polarization give the callan - gross relation and remove the pathological features of the original 1 + 1 dimensional description.   we conclude that rqcd gives a satisfactory description of the phenomenology and provides a deep understanding of both duality and dis.   # 1 # 1#2#30= -.50
we study the dipole picture for the description of deep inelastic scattering, focusing on the structure functions which are driven directly by the gluon distribution.   one performs estimates using the effective dipole cross section given by the glauber - mueller approach in qcd, which encodes the corrections due to the unitarity effects associated with the saturation phenomenon.   we also address issues about frame invariance of the calculations when analysing the observables.
in this work we analyze the beryllium - iron chemical diagram from the point of view of non - lte effects.   be abundances were re - calculated by considering non - lte corrections in ionization equilibrium ( logg ) and fe abundances (  ).   these corrections seem do not affect the linear relation between be - fe for metal - poor stars already found in the literature for lte derived abundances.   epsf    # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
this article reviews the status of event - shape studies in @xmath0 annihilation and dis.   it includes discussions of perturbative calculations, of various approaches to modelling hadronisation and of comparisons to data.   cern - th/2003 - 306 + lpthe-03 - 40 + hep - ph/0312283
we have analyzed _ xmm - newton _ observations of the high energy peaked blazar, pks 2155@xmath0304, made on 24 may 2002 in the 0.3  10 kev x - ray band.   these observations display a mini  flare, a nearly constant flux period and a strong flux increase.   we performed a time - resolved spectral study of the data, by dividing the data into eight segments.   we fitted the data with a power  law and a broken power  law model, and in some of the segments we found a noticeable spectral flattening of the source s spectrum below 10 kev.   we also performed  time - resolved " cross - correlation analyses and detected significant hard and soft lags ( for the first time in a single observation of this source ) during the first and last parts of the observation, respectively.   our analysis of the spectra, the variations of photon - index with flux as well as the correlation and lags between the harder and softer x - ray bands indicate that both the particle acceleration and synchrotron cooling processes make an important contribution to the emission from this blazar.   the hard lags indicate a variable acceleration process.   we also estimated the magnetic field value using the soft lags.   the value of the magnetic field is consistent with the values derived from the broad - band sed modeling of this source.   blazars : pks 2155@xmath0304, xmm - newton telescope : x - ray observations.
the model of diamagnetic phase transition in beryllium which takes into account the quasi @xmath0-dimensional shape of the fermi surface of beryllium is proposed.   it explains correctly the recent experimental data on observation of non - homogeneous phase in beryllium at the conditions of strong dhva effect when the strong correlation of electron gas results in instability of homogeneous phase and formation of condon domain structure.
we construct a new version of the higher covariant derivative regularization for a general @xmath0 supersymmetric gauge theory formulated in terms of @xmath1 superfields.   this regularization preserves both supersymmetries of the classical action, namely, the invariance under the manifest @xmath1 supersymmetry and under the second hidden on - shell supersymmetry.   the regularizing @xmath0 supersymmetric higher derivative term is found in the explicit form in terms of @xmath1 superfields.   thus, @xmath0 supersymmetry is broken only by the gauge fixing procedure.   then we analyze the exact nsvz @xmath2-function and prove that in the considered model its higher loop structure is determined by the anomalous dimension of the chiral superfield @xmath3 in the adjoint representation which is the @xmath0 superpartner of the gauge superfield @xmath4. using the background field method   we find that this anomalous dimension is related with the anomalous dimension of the hypermultiplet and vanishes if the effective action is invariant under @xmath0 background supersymmetry. as a consequence, in this case   the higher loop contributions to @xmath2-function also vanish  . the one - loop renormalization structure in the considered regularization is also studied by the explicit calculations of the one - loop renormalization constants.   keywords : supersymmetry, higher covariant derivative regularization, renormalization, @xmath2-function, supergraphs.
a model for epidemics on an adaptive network is considered.   nodes follow an sirs ( susceptible - infective - recovered - susceptible ) pattern.   connections are rewired to break links from non - infected nodes to infected nodes and are reformed to connect to other non - infected nodes, as the nodes that are not infected try to avoid the infection.   monte carlo simulation and numerical solution of a mean field model are employed.   the introduction of rewiring affects both the network structure and the epidemic dynamics.   degree distributions are altered, and the average distance from a node to the nearest infective increases.   the rewiring leads to regions of bistability where either an endemic or a disease - free steady state can exist.   fluctuations around the endemic state and the lifetime of the endemic state are considered.   the fluctuations are found to exhibit power law behavior.
we investigated with xmcd - peem magnetic imaging the magnetization reversal processes of nel caps inside bloch walls in self - assembled, micron - sized fe(110 ) dots with flux - closure magnetic state. in most cases   the magnetic - dependent processes are symmetric in field, as expected. however, some dots show pronounced asymmetric behaviors.   micromagnetic simulations suggest that the geometrical features ( and their asymmetry ) of the dots strongly affect the switching mechanism of the nel caps.
discovery of the cosmic reionization epoch would represent a significant milestone in cosmology.   we present keck spectroscopy of the quasar sdss 10440125, at @xmath0.   the spectrum shows a dramatic increase in the optical depth at observed wavelengths @xmath1 , corresponding to @xmath2. only a few small  , narrow transmission regions are present in the spectrum beyond that point, and out to the redshifts where the quasar signal begins.   we interpret this result as a signature of the trailing edge of the cosmic reionization epoch, which we estimate to occur around @xmath3 ( as indeed confirmed by subsequent observations by becker ), and extending down to @xmath4.   this behavior is expected in the modern theoretical models of the reionization era, which predict a patchy and gradual onset of reionization.   the remaining transmission windows we see may correspond to the individual reionization bubbles ( strmgren spheres ) embedded in a still largely neutral intergalactic medium, intersected by the line of sight to the quasar.   future spectroscopic observations of quasars at comparable or larger redshifts will provide a more detailed insight into the structure and extent of the reionization era.   ( h
we calculate the dynamical spin - spin correlation functions of a kondo dot coupled to two noninteracting leads held at different chemical potentials. to this end   we generalize a recently developed real - time renormalization group method in frequency space ( rtrg - fs  @xcite ) to allow the calculation of dynamical correlation functions of arbitrary dot operators in systems describing spin and/or orbital fluctuations.   the resulting two - loop rg equations are analytically solved in the weak - coupling regime.   this implies that the method can be applied provided either the voltage @xmath0 through the dot or the external magnetic field @xmath1 are sufficiently large, @xmath2, where the kondo temperature @xmath3 is the scale where the system enters the strong - coupling regime.   explicitly, we calculate the longitudinal and transverse spin - spin correlation and response functions as well as the resulting fluctuation - dissipation ratios.   the correlation functions in real - frequency space can be calculated in matsubara space without the need of any analytical continuation.   we obtain analytic results for the line - shape, the small- and large - frequency limits and several other features like the height and width of the peak in the transverse susceptibility at @xmath4, where @xmath5 denotes the renormalized magnetic field.   furthermore, we discuss how the developed method can be generalized to calculate dynamical correlation functions of other operators involving reservoir degrees of freedom as well.
within the mode - coupling theory ( mct ) for the evolution of structural relaxation in glass - forming liquids, correlation functions and susceptibility spectra are calculated characterizing the rotational dynamics of a top - down symmetric dumbbell molecule, consisting of two fused hard spheres immersed in a hard - sphere system.   it is found that for sufficiently large dumbbell elongations, the dynamics of the probe molecule follows the same universal glass - transition scenario as known from the mct results of simple liquids.   the @xmath0-relaxation process of the angular - index-@xmath1=1 response is stronger, slower and less stretched than the one for @xmath1=2, in qualitative agreement with results found by dielectric - loss and depolarized - light - scattering spectroscopy for some supercooled liquids. for sufficiently small elongations,   the reorientational relaxation occurs via large - angle flips, and the standard scenario for the glass - transition dynamics is modified for odd-@xmath1 responses due to precursor phenomena of a nearby type - a mct transition. in this case,   a major part of the relaxation outside the transient regime is described qualitatively by the @xmath2-relaxation scaling laws, while the @xmath0-relaxation scaling law is strongly disturbed.
we present new integral field spectroscopy of the gravitationally lensed broad absorption line ( bal ) quasar h1413 + 117, covering the ultraviolet to visible rest - frame spectral range.   we observe strong microlensing signatures in lensed image d, and we use this microlensing to simultaneously constrain both the broad emission and broad absorption line gas. by modeling the lens system over the range of probable lensing galaxy redshifts and using on a new argument based on the wavelength - independence of the broad line lensing magnifications, we determine that there is no significant broad line emission from smaller than @xmath020 light days.   we also perform spectral decomposition to derive the intrinsic broad emission line ( bel ) and continuum spectrum, subject to bal absorption.   we also reconstruct the intrinsic bal absorption profile, whose features allow us to constrain outflow kinematics in the context of a disk - wind model.   we find a very sharp, blueshifted onset of absorption of 1,500  km / s in both civ and nv that may correspond to an inner edge of a disk - wind s radial outflow.   the lower ionization siiv and aliii have higher - velocity absorption onsets, consistent with a decreasing ionization parameter with radius in an accelerating outflow.   there is evidence of strong absorption in the bel component which indicates a high covering factor for absorption over two orders of magnitude in outflow radius.
important questions concern the existence of excitonic strings in organic compounds and their signatures in the photophysics of these systems. a model in terms of hard core bosons   is proposed to study this problem in one dimension.   mainly the cases with two and three particles are studied for finite and infinite lattices, where analytical results are accessible.   it is shown that if bi - excitonic states exist, three - excitonic and even, _ n_-excitonic strings, at least in a certain range of parameters, will exist. moreover,   the behaviour of the transitions from one exciton to the biexciton is fully clarified.   the results are in agreement with exact finite cluster diagonalizations of several model hamiltonians.
using axisymmetric simulations coupling special relativistic mhd, an approximate post - newtonian gravitational potential and two - moment neutrino transport, we show different paths for the formation of either protomagnetars or stellar mass black holes.   the fraction of prototypical stellar cores which should result in collapsars depends on a combination of several factors, among which the structure of the progenitor star and the profile of specific angular momentum are probably the foremost.   along with the implosion of the stellar core, we also obtain supernova - like explosions driven by neutrino heating and hydrodynamic instabilities or by magneto - rotational effects in cores of high - mass stars. in the latter case,   highly collimated, mildly relativistic outflows are generated.   we find that after a rather long post - collapse phase ( lasting @xmath0sec ) black holes may form in cases both of successful and failed supernova - like explosions.   a basic trend is that cores with a specific angular momentum smaller than that obtained by standard, one - dimensional stellar evolution calculations form black holes ( and eventually collapsars ).   complementary, protomagnetars result from stellar cores with the standard distribution of specific angular momentum obtained from prototypical stellar evolution calculations including magnetic torques and moderate to large mass loss rates.   supernovae : general - gamma - ray bursts : general
human vision greatly benefits from the information about sizes of objects.   the role of size in several visual reasoning tasks has been thoroughly explored in human perception and cognition.   however, the impact of the information about sizes of objects is yet to be determined in ai.   we postulate that this is mainly attributed to the lack of a comprehensive repository of size information. in this paper, we introduce a method to automatically infer object sizes, leveraging visual and textual information from web. by maximizing the joint likelihood of textual and visual observations, our method learns reliable relative size estimates, with no explicit human supervision. we introduce the relative size dataset and show that our method outperforms competitive textual and visual baselines in reasoning about size comparisons.
phylogenetic trees are a central tool in understanding evolution.   they are typically inferred from sequence data, and capture evolutionary relationships through time.   it is essential to be able to compare trees from different data sources ( e.g.  several genes from the same organisms ) and different inference methods.   we propose a new metric for robust, quantitative comparison of rooted, labeled trees.   it enables clear visualizations of tree space, gives meaningful comparisons between trees, and can detect distinct islands of tree topologies in posterior distributions of trees.   this makes it possible to select well - supported summary trees.   we demonstrate our approach on dengue fever phylogenies.
the dynamics of electrons in the presence of a positive ion is considered for conditions of weak electron - electron couping but strong electron - ion coupling.   the equilibrium electron density and electric field time correlation functions are evaluated for semi - classical conditions using a classical statistical mechanics with a regularized electron - ion interaction for md simulation. the theoretical analysis for the equilibrium state   is obtained from the corresponding nonlinear vlasov equation.   time correlation functions for the electrons are determined from the linearized vlasov equation.   the resulting electron dynamics is described in terms of a distribution of single electron - ion trajectories screened by an inhomogeneous electron gas dielectric function.   the results are applied to calculation of the autocorrelation function for the electron electric field at the ion for @xmath0, including conditions of strong electron - ion coupling.   the electron stopping power and self - diffusion coefficient are determined from these results, and all properties calculated are compared with those obtained from semi - classical molecular dynamics simulation.   the agreement with semi - classical md simulation is found to be reasonable.   the theoretical description provides an instructive interpretation for the strong electron - ion results.
in order to study photomultiplier s short - term gain stability at high counting rate, we constructed an led pulsed light source and its output monitor system. for the monitor system  , we employed a photon counting method using a photomultiplier as a monitor photon detector.   it is found that the method offers a simple way to monitor outputs from a pulsed light source and that, together with an led light source, it provides a handy way to investigate photomultiplier s rate effects.   1em _   pacs :  _ 29.40.mc ; 85.60.ha   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,
we discuss two experiments - the very small array ( vsa ) and the arcminute microkelvin imager ( ami ) - and their prospects for observing the cmb at high angular multipoles.   whilst the vsa is primarily designed to observe primary anisotropies in the cmb, ami is designed to image secondary anisotropies via the sunyaev - zeldovich effect.   the combined @xmath0-range of these two instruments is between @xmath1 and @xmath2.
we report results of a  high - resolution imager ( hri ) observation of the x - ray error box given by the  wide field camera for the gamma - ray burst that occurred on 1997 february 28.   the observation started 10 days after the burst and ended three days later, with a total exposure of 34.3  ks.   an x - ray source was detected within the 3@xmath0 wfc error box and its position determined with a 10@xmath1 radius accuracy.   the source position is in the  narrow field instrument source error box and is coincident ( to within 2@xmath1 ) with the optical transient associated with grb970228.   this is the most precise position obtained for an x - ray afterglow and confirms that the x - ray and optical afterglows have the same origin.   we present the 0.12.4  kev combined hri and  low - energy concentrator spectrometer decay light curve which can be well fit with a power - law.   the decay is consistent with that measured at higher energies ( 210  kev ) with the  medium - energy concentrator spectrometer.   # 1 # 2 # 3 # 4    = 2em = 1 by 0em # 1, _ # 2 _, * # 3 *, # 4.   # 1    = 2em = 1 by 0em # 1.   1s^-1 2cm^-2 _astron.   astrophys.
the standard lower limit for the mass of white dwarfs ( wds ) with a c / o core is roughly 0.5 m@xmath0. in the present work we investigated the possibility to form c / o wds with mass as low as 0.33 m@xmath0.   both the pre - wd and the cooling evolution of such nonstandard models will be described.
we consider a model proposed earlier by us for describing a form of plastic instability found in creep experiments.   the model consists of three types of dislocations and some transformations between them.   the model is known to reproduce a number of experimentally observed features.   the mechanism for the phenomenon has been shown to be hopf bifurcation with respect to physically relevant drive parameters.   here, we present a mathematical analysis of adiabatically eliminating the fast mode and obtaining a ginzburg - landau equation for the slow modes associated with the steps on creep curve.   the transition to the instability region is found to be one of subcritical bifurcation over most of the interval of one of the parameters while supercritical bifurcation is found in a narrow mid - range of the parameter.   this result is consistent with experiments.   the dependence of the amplitude and the period of strain jumps on stress and temperature derived from the ginzburg - landau equation are also consistent with experiments. on the basis of detailed numerical solution via power series expansion  , we show that high order nonlinearities control a large portion of the subcritical domain.   = -2.5 cm = -2 cm
we study glueball @xmath0 production in gluonic penguin decay @xmath1, using the next - to - leading order @xmath2 gluonic penguin interaction and effective couplings of a glueball to two perturbative gluons.   subsequent decays of a scalar glueball are described by using techniques of effective chiral lagrangian to incorporate the interaction between a glueball and pseudoscalar mesons. mixing effects between the pure glueball with other mesons   are considered. identifying the @xmath3 to be a scalar glueball  , we find that both the top and charm penguin to be important and obtain a sizable branching ratio for @xmath4 of order @xmath5, where the effective coupling strength @xmath6 is estimated to be @xmath7 gev@xmath8 using experimental data for the branching ratio of @xmath9 based on chiral lagrangian estimate.   an alternative perturbative qcd based estimation of @xmath6 is a factor of 20 larger, which would imply a much enhanced branching ratio.   glueball production from this rare semi - inclusive @xmath10 decay can be probed at the lhcb and belle ii to narrow down the allowed parameter space.   similar branching ratio is expected for the pseudoscalar glueball.   we also briefly comment on the case of vector and tensor glueballs.
theoretical studies of quarkonia can elucidate some of the important properties of the quark  gluon plasma,   the state of matter realised when the temperature exceeds @xmath0 mev, currently probed by heavy - ion collisions experiments at bnl and the lhc.   we report on our results of lattice studies of bottomonia for temperatures in the range @xmath1, introducing and discussing the methodologies we have applied.   of particular interest is the analysis of the spectral functions, where bayesian methods borrowed and adapted from nuclear and condensed matter physics have proven very successful.
a model of dense plasmas relying on the superconfiguration approximation is presented. in each superconfiguration   the nucleus is totally screened by the electrons in a wigner - seitz sphere ( ion - sphere model ).   superconfigurations of the same charge are grouped into ions.   it is shown that boundary values of the wavefunctions play a crucial role in the form of the virial theorem from which the pressure formula is derived.   finally, a condition is presented and discussed, which makes the ion - sphere model variational when bound electrons are treated quantum - mechanically and free electrons quasi - classically.
infrared imaging surveyor ( ) is a satellite which will be launched in the beginning of 2003.   one of the main purposes of the _ iris _ mission is an all - sky survey at far - infrared ( fir ) with a flux limit much deeper than that of _ iras_. in order to examine the performance of the survey, we estimated the fir galaxy counts in four ( 50, 70, 120, and 150 @xmath0 m ) bands based on some models.   we adopted a multicomponent model which consists of cirrus and starburst components for galaxy spectra, and the nearby fir luminosity function derived from that of _ iras _ galaxies.   we derived the number counts, redshift distributions, and infrared diffuse background radiation spectra for i ) no evolution, ii ) pure luminosity evolution, iii ) pure density evolution with @xmath1 and @xmath2.   we found that a large number of galaxies ( @xmath3 in the whole sky ) will be detected in this survey. with the aid of a vast number of detection  , we will detect the effect of galaxy evolution, and evaluate the amplitude of evolution at least in the nearby universe in the  survey, though it will be still difficult to constrain which type of evolution takes place from the number count alone.   we also studied the estimation of redshifts of detected galaxies by their infrared colors alone.   although significant contamination takes place among nearby faint galaxies and high-@xmath4 ones, we found that rough estimation of galaxy redshift can be practicable by jointly using present and future optical surveys.
we present the luminosity function to very faint magnitudes for the globular clusters in m87, based on a 30 orbit _ hubble space telescope ( hst ) _   wfpc2 imaging program.   the very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before.   we compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between m87 and the milky way.   we also find with high statistical significance that the m87 luminosity function is broader than that of the milky way.   we discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems.   our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence.   in addition, the rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. we also find that the mass - size relation has very little slope, indicating that there is almost no increase in the size of a cluster with increasing mass.
we consider a model of a two - dimensional interface of the sos type, with finite - range, even, strictly convex, twice continuously differentiable interactions.   we prove that, under an arbitrarily weak potential favouring zero - height, the surface has finite mean square heights.   we consider the cases of both square well and @xmath0 potentials.   these results extend previous results for the case of nearest - neighbours gaussian interactions in @xcite and @xcite.   we also obtain estimates on the tail of the height distribution implying, for example, existence of exponential moments. in the case of the @xmath1 potential, we prove a spectral gap estimate for linear functionals.   we finally prove exponential decay of the two - point function ( 1 ) for strong @xmath1-pinning and the above interactions, and ( 2 ) for arbitrarily weak @xmath1-pinning, but with finite - range gaussian interactions.
we study the intrinsic properties of attractors in the boolean dynamics in complex network with scale - free topology, comparing with those of the so - called random kauffman networks.   we have numerically investigated the frozen and relevant nodes for each attractor, and the robustness of the attractors to the perturbation that flips the state of a single node of attractors in the relatively small network ( @xmath0 ).   it is shown that the rate of frozen nodes in the complex networks with scale - free topology is larger than that in the random kauffman model.   furthermore, we have found that in the complex scale - free networks with fluctuations of in - degree number the attractors are more sensitive to the state flip of a highly connected node than to the state flip of a less connected node.   boolean dynamics ; attractor ; scale - free network ; intrinsic property ; robustness ; frozen nodes
the paper contains a description of a first attempt to understand the extremely inelastic high energy hadron collisions, when the multiplicity of produced hadrons considerably exceeds its mean value.   problems with existing model predictions are discussed.   the real - time finite - temperature @xmath0-matrix theory is built to have a possibility to find model - free predictions.   this allows to include the statistical effects into consideration and build the phenomenology.   the questions to experiment are formulated at the very end of the paper.   = 22.8cm= 15.65 cm = 0.5cm= -2cm= -1.4 cm           _ e2 - 2000 - 217 _    * very high multiplicity hadron processes * + 0.5 cm _ j.manjavidze@xmath1 _ and _ a.sissakian@xmath2 _    @xmath1joint institute for nuclear research, djelepov lab. of nucl.   problems, 141980 dubna, russia, e - mail : joseph@nusun.jinr.ru + tel. : ( 09621 ) 6 35 17, fax : ( 09621 ) 6 66 66 0.5 cm @xmath2joint institute for nuclear research, bogolyubov lab. of theor.   physics, 141980 dubna, russia, e - mail : sisakian@jinr.ru + tel.   ( 09621 ) 6 22 68, fax : ( 09621 ) 6 58 91    0.5 cm    keywords : multiple production, stochastization, qcd, integrability 0.5 cm    pacs numbers : 13.85, 12.38, 05.70.l, 05.30
in this paper we present a novel genetic algorithm ( ga ) solution to a simple yet challenging commercial puzzle game known as the zen puzzle garden ( zpg ).   we describe the game in detail, before presenting a suitable encoding scheme and fitness function for candidate solutions.   we then compare the performance of the genetic algorithm with that of the a * algorithm.   our results show that the ga is competitive with informed search in terms of solution quality, and significantly out - performs it in terms of computational resource requirements.   we conclude with a brief discussion of the implications of our findings for game solving and other  real world " problems.
this article presents direct numerical simulations of the growth of turbulent spots in the transitional regime of plane couette flow.   a quantitative description of the growth process and of the detail of the quadrupolar flow around the spot is given.   focus is put on formation of spanwise vorticity in the velocity streaks that resembles a secondary shear instability.   the main features of the instability ( coherence lengths, advection velocity ) are studied in the context of the turbulent spot, below and above the threshold reynolds number of appearance of the oblique turbulent bands of plane couette flow.   keywords : transition, wall - bounded turbulence, shear flows instabilities,    pacs : 47.27.cn, 47.27.n-, 47.20.ft
the role of angular momentum in a @xmath0-dimensional rotating thin - shell wormhole ( tsw ) is considered.   particular emphasis is made on stability when the shells ( rings ) are counterrotating.   we find that counter - rotating halves make the tsw supported by the equation of state of a linear gas more stable. under a small velocity dependent perturbation  , however, it becomes unstable.
in this paper a method is proposed which uses data mining techniques based on rough sets theory to select neighborhood and determine update rule for cellular automata ( ca ). according to the proposed approach  , neighborhood is detected by reducts calculations and a rule - learning algorithm is applied to induce a set of decision rules that define the evolution of ca.   experiments were performed with use of synthetic as well as real - world data sets.   the results show that the introduced method allows identification of both deterministic and probabilistic ca - based models of real - world phenomena.
bursting neurons fire rapid sequences of action potential spikes followed by a quiescent period.   the basic dynamical mechanism of bursting is the slow currents that modulate a fast spiking activity caused by rapid ionic currents.   minimal models of bursting neurons must include both effects.   we considered one of these models and its relation with a generalized kuramoto model, thanks to the definition of a geometrical phase for bursting and a corresponding frequency.   we considered neuronal networks with different connection topologies and investigated the transition from a non - synchronized to a partially phase - synchronized state as the coupling strength is varied.   the numerically determined critical coupling strength value for this transition to occur is compared with theoretical results valid for the generalized kuramoto model.
we present the design and experimental proof of principle of a low threshold optical parametric oscillator ( opo ) that continuously oscillates over a large bandwidth allowed by phase matching.   the large oscillation bandwidth is achieved with a selective two - photon loss that suppresses the inherent mode competition, which tends to narrow the bandwidth in conventional opos.   our design performs pairwise mode - locking of many frequency pairs, in direct equivalence to passive mode - locking of ultrashort pulsed lasers.   the ability to obtain high powers of continuous _ and _ broadband down - converted light enables the optimal exploitation of the correlations within the down - converted spectrum, thereby strongly affecting two - photon interactions even at classically high power levels, and opening new venues for applications such as two - photon spectroscopy and microscopy and optical spread spectrum communication.
our understanding of the nature of dla systems at large redshifts, ostensibly progenitors of normal disk galaxies, depends critically on their direct identifications with galaxies, and the resulting measurements of their properties.   a few such objects have now been found, reaching out to @xmath0.   their observed luminosities are @xmath1, star formation rates @xmath2 a few @xmath3/yr, physical sizes @xmath4 kpc, and velocity fields of a few hundred km / s, implying masses @xmath5. while their morphology remains uncertain, the observed properties are consistent with those expected of young disk galaxies in the early stages of formation.   we also find a statistically significant excess of foreground galaxies near lines of sight to luminous quasars at @xmath6.   this suggests a systematical gravitational lensing magnification of such quasar samples, possibly with important consequences for the estimates of the quasar luminosity function at high redshifts, and the deduced @xmath7 in dla systems found in their spectra.
quantitatively - unexplained stationary waves or ridges often encircle icicles. such waves form when roughly 0.1 mm - thick layers of water flow down the icicle.   these waves typically have a wavelength of 1 cm approximately independent of external temperature, icicle thickness, and the volumetric rate of water flow. in this paper   we show that these waves can not be obtained by naive mullins - sekerka instability, but are caused by a quite new surface instability related to the thermal diffusion and hydrodynamic effect of thin water flow.
we report the discovery of khz oscillations ( qpos ) in three rossi x  ray timing explorer observations of the low mass x  ray binary ( lmxb ). in one of the observations we detect a khz qpo with a characteristic frequency of @xmath0 hz, while in the other two observations we detect twin qpos at characteristic frequencies of @xmath1 hz, @xmath2 hz and @xmath3 hz, @xmath4 hz. all detections happen when was in its high intensity soft state, and their single trial significance are in the 3.1 - 7.5 @xmath5 range. the frequency difference in the centroid frequencies of the twin khz qpos ( @xmath6 hz ) is one of the largest seen till date.   the fractional rms amplitude of the upper khz qpo varies between @xmath7 and @xmath8.  , with a persistent luminosity close to 1% of the eddington limit, is among the small group of low luminosity khz qpo sources and has the highest rms for the upper khz qpo detected in any source.   the x - ray spectral and variability characteristics of this source indicate its atoll source nature.   stars : individual :  stars : binaries  stars : neutron  x  rays : stars
we report a simultaneous ground and space - based photometric study of the @xmath0  cephei star @xmath1  eridani.   half a year of observations have been obtained by four of the five satellites constituting brite - constellation, supplemented with ground - based photoelectric photometry.   we show that carefully combining the two data sets virtually eliminates the aliasing problem that often hampers time - series analyses.   we detect 40 periodic signals intrinsic to the star in the light curves. despite a lower detection limit we do not recover all the pressure and mixed modes previously reported in the literature, but we newly detect six additional gravity modes.   this behaviour is a consequence of temporal changes in the pulsation amplitudes that we also detected for some of the p modes.   we point out that the dependence of theoretically predicted pulsation amplitude on wavelength is steeper in visual passbands than those observationally measured, to the extent that the three dominant pulsation modes of @xmath1 eridani would be incorrectly identified using data in optical filters only.   we discuss possible reasons for this discrepancy.   stars : variables : other  stars : early - type  stars : oscillations  stars : individual : @xmath1  eridani  techniques : photometric
we explain how to implement, in the context of projected entangled - pair states ( peps ), the general procedure of _ fermionization _ of a tensor network introduced in [ p. corboz, g. vidal, phys.   rev.   b 80, 165129 ( 2009 ) ].   the resulting fermionic peps, similar to previous proposals, can be used to study the ground state of interacting fermions on a two - dimensional lattice. as in the bosonic case  , the cost of simulations depends on the amount of entanglement in the ground state and not directly on the strength of interactions.   the present formulation of fermionic peps leads to a straightforward numerical implementation that allowed us to recycle much of the code for bosonic peps.   we demonstrate that fermionic peps are a useful variational ansatz for interacting fermion systems by computing approximations to the ground state of several models on an infinite lattice. for a model of interacting spinless fermions,   ground state energies lower than hartree - fock results are obtained, shifting the boundary between the metal and charge - density wave phases. for the @xmath0 model, energies comparable with those of a specialized gutzwiller - projected ansatz are also obtained.
power grid outages cause huge economical and societal costs.   disruptions in the power distribution grid are responsible for a significant fraction of electric power unavailability to customers  . the impact of extreme weather conditions, continuously increasing demand, and the over - ageing of assets in the grid, deteriorates the safety of electric power delivery in the near future.   it is this dependence on electric power that necessitates further research in the power distribution grid security assessment.   thus measures to analyse the robustness characteristics and to identify vulnerabilities as they exist in the grid are of utmost importance.   this research investigates exactly those concepts- the vulnerability and robustness of power distribution grids from a topological point of view, and proposes a metric to quantify them with respect to assets in a distribution grid.   real - world data is used to demonstrate the applicability of the proposed metric as a tool to assess the criticality of assets in a distribution grid.    *   _ keywords _ * power distribution grid, topological robustness, structural vulnerability, metric, complex networks
the aim of our observations is to investigate the intranight variability properties and the spectral variability of bl lacertae.   799 optical multi - band observations were intensively made with the beijing - arizona - taiwan - connecticut ( batc ) 60/90 cm schmidt telescope during the outburst composed of two subsequent flares in 2005.   the second flare, whose rising phase lasted at least 44 days, was observed with amplitudes of more than 1.1 mag in three batc optical bands. in general, on intranight timescale the amplitude of variability and the variation rate are larger at the shorter wavelength, and the variation rate is comparable in the rising and decaying phases within each band. a possible time lag between the light curves in bands _   e _ and _ m _, around 11.6 minutes, was obtained.   based on the analysis of the colour index variation with the source brightness, the variability of bl lacertae can be interpreted as having two components : a `` strongly - chromatic '' intranight component and a `` mildly - chromatic '' internight component, which may be the results of both intrinsic physical mechanism and geometric effects.       galaxies : bl lacertae objects : general  bl lacertae objects : individual : bl lacertae  galaxies : photometry
we study the ground - state three - quark ( 3q ) potential @xmath0 and the excited - state 3q potential @xmath1 using su(3 ) lattice qcd. from the accurate and thorough calculation for more than 300 different patterns of 3q systems,   the static ground - state 3q potential @xmath0 is found to be well described by the coulomb plus y - type linear potential, i.e., y - ansatz, within 1%-level deviation. with lattice   qcd, we calculate also the excited - state potential in the 3q system, and find the gluonic excitation energy, @xmath2, to be about 1 gev. this large gluonic - excitation energy would play an essential role to the success of the quark model for the low - lying hadrons in terms of the absence of the gluonic mode.
the effects of polymer additives on rayleigh  taylor ( rt ) instability of immiscible fluids is investigated using the oldroyd - b viscoelastic model. analytic results obtained exploiting the phase - field approach show that in polymer solution the growth rate of the instability speeds up with elasticity ( but remains slower than in the pure solvent case ).   numerical simulations of the viscoelastic binary fluid model confirm this picture.
a considerable fraction of galactic supernova remnants ( snrs ) characterize flat spectral indices ( @xmath0 )  . there are several explanations of the flat radio spectra of snrs in the present literature.   the most of models involve a significant contribution of the second - order fermi mechanism but some of them also discuss high compressions ( @xmath1 ), contribution of secondary electrons left over from the decay of charged pions, as well as the possibility of thermal contamination. in the case of expansion in high density environment, intrinsic thermal bremsstrahlung could theoretically shape the radio spectrum of an snr and also account for observable curved  `` concave up '' radio spectra of some galactic snrs. this model could also shed a light on the question of flat spectral indices determined in some galactic snrs.   on the other hand, present knowledge of the radio continuum spectra ( integrated flux densities at different frequencies ) of snrs prevent definite conclusions about the significance of proposed models so the question on flat spectral indices still remains open.   new observations, especially at high radio continuum frequencies, are expected to solve these questions in the near future.   finally, as there is a significant connection between the majority of galactic snrs with flat integrated radio spectrum and their detection in @xmath2-rays as well as detection of radiative recombination continua in their x - ray spectra, the analysis of high energy properties of these snrs is very important.
the derivation of general performance benchmarks is important in the design of highly optimized heat engines and refrigerators. to obtain them,   one may model phenomenologically the leading sources of irreversibility ending up with results which are model - independent, but limited in scope.   alternatively, one can take a simple physical system realizing a thermodynamic cycle and assess its optimal operation from a complete microscopic description.   we follow this approach in order to derive the coefficient of performance at maximum cooling rate for _ any _ endoreversible quantum refrigerator. at striking variance with the _ universality _ of the optimal efficiency of heat engines, we find that the cooling performance at maximum power is crucially determined by the details of the specific system - bath interaction mechanism.   a closed analytical benchmark is found for endoreversible refrigerators weakly coupled to unstructured bosonic heat baths : an ubiquitous case study in quantum thermodynamics.
a successful interpretation of the cross sections for elastic and inelastic vector meson production can be made if one assumes the underlying dynamics to be governed by hard partonic subprocesses. extending these partonic approaches to longitudinally polarized electron - proton collisions, we estimate the expected production asymmetries at the hera collider.   the anticipated statistical errors on these asymmetries mostly turn out to be larger than the asymmetries themselves, such that an experimental observation of these asymmetries at hera looks not feasible.   * vector meson production at a polarized hera collider *     +   +   +    * abstract *    a successful interpretation of the cross sections for elastic and inelastic vector meson production can be made if one assumes the underlying dynamics to be governed by hard partonic subprocesses. extending these partonic approaches to longitudinally polarized electron - proton collisions, we estimate the expected production asymmetries at the hera collider.   the anticipated statistical errors on these asymmetries mostly turn out to be larger than the asymmetries themselves, such that an experimental observation of these asymmetries at hera looks not feasible.   _ contribution to the proceedings of the `` workshop on physics with polarized protons at hera '', desy, march   september 1997.   _    * vector meson production at a polarized hera collider *     +   +   +
the goal of a small and dedicated satellite called the `` continuous spectro - photometry of black holes '' or cspob is to provide the essential tool for the theoretical understanding of the hydrodynamic and magneto - hydrodynamic flows around black holes. in its life time of about three to four years, only a half a dozen black holes   will be observed continuously with a pair of cspobs.   changes in the spectral and temporal variability properties of the high - energy emission would be caught as they happen.   several important questions are expected to be answered and many puzzles would be sorted out with this mission.   address = s.n.   bose national center for basic sciences, jd - block, salt lake, kolkata, 700098, altaddress = indian centre of space physics, chakraba@bose.res.in ( principal investigator )     address = indian centre for space physics, 43 chalantika, garia station rd.  , kolkata 700098     address = indian centre for space physics, 43 chalantika, garia station rd.  , kolkata 700098     address = indian centre for space physics, 43 chalantika, garia station rd.  , kolkata 700098     address = indian centre for space physics, 43 chalantika, garia station rd.  , kolkata 700098, altaddress = on deputation from indian space research organization     address = indian centre for space physics, 43 chalantika, garia station rd.  , kolkata 700098, altaddress = on deputation from indian space research organization     address = tata institute of fundamental research, homi bhabha road, col
multiplicity is a key statistic for understanding the formation of very low mass ( vlm ) stars and brown dwarfs.   currently, the separation distribution of vlm binaries remains poorly constrained at small separations ( @xmath0 1 au ), leading to uncertainty in the overall binary fraction.   we approach this problem by searching for late - m / early - l plus t dwarf spectral binaries whose combined light spectra exhibit distinct peculiarities, allowing for separation - independent identification.   we define a set of spectral indices designed to identify these systems, and use a spectral template fitting method to confirm and characterize spectral binary ( sb ) candidates from a library of 815 spectra from the spex prism spectral libraries.   we present eleven new binary candidates, confirm three previously reported candidates and rule out two previously identified candidates, all with primary and secondary spectral types between m7-l7 and t1-t8, respectively.   we find that subdwarfs and blue l dwarfs are the primary contaminants in our sample and propose a method for segregating these sources.   if confirmed by follow - up observations, these systems may add to the growing list of tight separation binaries, whose orbital properties may yield further insight into brown dwarf formation scenarios.
we report experimental results on the behavior of an ensemble of inelastically colliding particles, excited by a vibrated piston in a vertical cylinder.   when the particle number is increased, we observe a transition from a regime where the particles have erratic motions ( granular gas ) to a collective behavior where all the particles bounce like a nearly solid body. in the gaslike regime  , we measure the pressure at constant volume, and the bed expansion at constant external pressure, as a function of the number @xmath0 of particles.   we also measure the density of particles as a function of the altitude, and find that the atmosphere  is exponential far enough from the piston. from these three independent measurements,   we determine a state equation  between pressure, volume, particle number and the vibration amplitude and frequency.
we present the spitzer archival far - infrared extragalactic survey ( safires ).   this program produces refined mosaics and source lists for all far - infrared extragalactic data taken during the more than six years of the cryogenic operation of the @xmath0.   the safires products consist of far - infrared data in two wavelength bands ( 70  and 160 ) across approximately 180 square degrees of sky, with source lists containing far - infrared fluxes for almost 40,000 extragalactic point sources.   thus, safires provides a large, robust archival far - infrared data set suitable for many scientific goals.
unified generalized chaplygin gas models assuming an interaction between dark energy and dark matter fluids have been previously proposed. following these ideas  , we consider a particular relation between dark densities, which allows the possibility of a time varying equation of state for dark energy that crosses the phantom divide at a recent epoch.   moreover, these densities decay during all the evolution of the universe, avoiding a big rip.   we find also a scaling solution, i.e. these densities are asymptotically proportional in the future, which contributes to the solution of the coincidence problem.
the tanami ( tracking agn with austral milliarcsecond interferometry ) and associated programs provide comprehensive radio monitoring of extragalactic gamma - ray sources south of declination @xmath0 degrees.   joint quasi - simultaneous observations between the fermi gamma - ray space telescope and ground based observatories allow us to discriminate between competing theoretical blazar emission models.   high resolution vlbi observations are the only way to spatially resolve the sub - parsec level emission regions where the high - energy radiation originates.   the gap from radio to gamma - ray energies is spanned with near simultaneous data from the swift satellite and ground based optical observatories.   we present early results from the tanami program in the context of this panchromatic suite of observations.
radio quasar sightlines with strong mgii absorption lines display statistically enhanced faraday rotation measures ( rm ) indicating the presence of additional magneto - active plasma with respect to sightlines free of such absorption. in this letter  , we use multi - color optical imaging to identify the likely galaxies hosting the magneto - active plasma, and to constrain the location of the latter with respect to the putative parent halo.   we find that all of the sightlines with high @xmath0 pass within 50 kpc of a galaxy and that the @xmath0 distribution for low impact parameters, @xmath1 kpc, is significantly different than for larger impact parameters.   in addition, we find a decrease in the ratio of the polarization at 21 cm and 1.5 cm, @xmath2, towards lower d. these two effects are most likely related, strengthen the association of excess @xmath0 with intervening galaxies, and suggest that intervening galaxies operate as inhomogeneous faraday screens.   these results are difficult to reconciliate with only a disk model for the magnetic field but are consistent with highly magnetized winds associated with mgii systems.   we infer strong magnetic fields of a few tens of @xmath3 g, consistent with values required by the lack of evolution of the fir - radio correlation at high redshifts.   finally, these findings lends support to the idea that the small scale helicity bottleneck of @xmath4-@xmath5 galactic dynamos can be significantly alleviated via galatic winds.
a brief review of some of the central ideas, terminology and techniques of the technology of orientifolds and d  branes is presented.   some applications are reviewed, including the construction of dual solitonic strings in the context of string / string duality, the computation of the bekenstien  hawking entropy / area law for extremal black  holes, and the construction of @xmath0 string vacua in dimensions lower than ten.   ( presented at susy  96, university of maryland at college park, may 29june 1, 1996. ) -0.5truecm    epsf.tex    # 1e^#1
we describe a compression method for floating - point astronomical images that gives compression ratios of 6  10 while still preserving the scientifically important information in the image.   the pixel values are first preprocessed by quantizing them into scaled integer intensity levels, which removes some of the uncompressible noise in the image.   the integers are then losslessly compressed using the fast and efficient rice algorithm and stored in a portable fits format file.   quantizing an image more coarsely gives greater image compression, but it also increases the noise and degrades the precision of the photometric and astrometric measurements in the quantized image.   dithering the pixel values during the quantization process can greatly improve the precision of measurements in the images.   this is especially important if the analysis algorithm relies on the mode or the median which would be similarly quantized if the pixel values are not dithered.   we perform a series of experiments on both synthetic and real astronomical ccd images to quantitatively demonstrate that the magnitudes and positions of stars in the quantized images can be measured with the predicted amount of precision. in order to encourage wider use of these image compression methods,   we have made available a pair of general - purpose image compression programs, called fpack and funpack, which can be used to compress any fits format image.
we analyze the recently released fermi - lat data on the sum of electrons and positrons. compared to a conventional, pre - fermi, background model, a surprising excess in the several hundred gev range   is found and here we analyze it in terms of dark matter models.   we also compare with newly published results from pamela and hess, and find models giving very good fits to these data sets as well.   if this dark matter interpretation is correct, we also predict the possibility of a sharp break in the diffuse gamma ray spectrum coming from final state radiation.
the young @xmath0  orionis cluster in the orion belt is an incomparable site for studying the formation and evolution of high - mass, solar - like, and low - mass stars, brown dwarfs, and substellar objects below the deuterium burning mass limit. the first version of the mayrit catalogue was a thorough data compilation of cluster members and candidates, which is regularly used by many authors of different disciplines.   i show two new applications of the catalogue and advance preliminar results on very wide binarity and the initial mass function from 18 to 0.035@xmath1 in @xmath0  orionis.   the making - up of a new version of the mayrit catalogue with additional useful data is in progress.   address = departamento de astrofsica y ciencias de la atmsfera, facultad de fsica, universidad complutense de madrid, e-28040 madrid, spain,email=caballero@astrax.fis.ucm.es
continuing work initiated in an earlier publication [ ishihara, suzuki, ono, kitamura, asada, phys.   rev.   d * 94 *, 084015 ( 2016 ) ], we discuss a method of calculating the bending angle of light in a static, spherically symmetric and asymptotically flat spacetime, especially by taking account of the finite distance from a lens object to a light source and a receiver. for this purpose, we use the gauss - bonnet theorem to define the bending angle of light, such that the definition can be valid also in the strong deflection limit.   finally, this method is applied to schwarzschild spacetime in order to discuss also possible observational implications.   the proposed corrections for sgr a@xmath0 for instance are able to amount to @xmath1 arcseconds for some parameter range, which may be within the capability of near - future astronomy, while also the correction for the sun in the weak field limit is @xmath1 arcseconds.
we solve the local and global structural identifiability problems for viscoelastic mechanical models represented by networks of springs and dashpots.   we propose a very simple characterization of both local and global structural identifiability based on _ identifiability tables _, with the purpose of providing a guideline for constructing arbitrarily complex, identifiable spring - dashpot networks.   we illustrate how to use our results in a number of examples and point to some applications in cardiovascular modeling.
we investigate the various time - dependent bubble spacetimes that can be obtained from double analytic continuation of asymptotically locally flat / ads spacetimes with nut charge.   we find different time - dependent explicit solutions of general relativity from double analytic continuations of taub - nut(-ads ) and kerr - nut(-ads ) spacetimes.   one solution in particular has milne - like evolution throughout, and another is a nut - charged generalization of the ads soliton.   these solutions are all four dimensional. in certain situations   the nut charge induces an ergoregion into the bubble spacetime and in other situations it quantitatively modifies the evolution of the bubble, as when rotation is present. in dimensions greater than four,   no consistent bubble solutions are found that have only one timelike direction.   hep - th/0207123 + watpphys - th02/04    * nutty bubbles * +    a.m. ghezelbash@xmath0 and r. b. mann@xmath1 + @xmath2department of physics, university of waterloo, + waterloo, ontario n2l 3g1, canada + @xmath0department of physics, alzahra university, + tehran 19834, iran +   +
since the complexity of the practical environment, many distributed networked systems can not be illustrated with the integer - order dynamics and only be described as the fractional - order dynamics.   suppose multi - agent systems will show the individual diversity with difference agents, where the heterogeneous ( integer - order and fractional - order ) dynamics are used to illustrate the agent systems and compose integer - fractional compounded - order systems.   applying laplace transform and frequency domain theory of the fractional - order operator, consensus of delayed multi - agent systems with directed weighted topologies is studied.   since integer - order model is the special case of fractional - order model, the results in this paper can be extend to the systems with integer - order models.   finally, numerical examples are used to verify our results.    coordination control ; multi - agent systems ; heterogeneous dynamics ; compounded - order ; communication delays.   + * pacs * : 89.75.f6 ; 05.30.pr
how cosmic rays sample the multi - phase interstellar medium ( ism ) in starburst galaxies has important implications for many science goals, including evaluating the cosmic ray calorimeter model for these systems, predicting their neutrino fluxes, and modeling their winds. here  , we use monte carlo simulations to study cosmic ray sampling of a simple, two - phase ism under conditions similar to those of the prototypical starburst galaxy m82. the assumption that cosmic rays sample the mean density of the ism in the starburst region   is assessed over a multi - dimensional parameter space where we vary the number of molecular clouds, the galactic wind speed, the extent to which the magnetic field is tangled, and the cosmic ray injection mechanism.   we evaluate the ratio of the emissivity from pion production in molecular clouds to the emissivity that would be observed if the cosmic rays sampled the mean density, and seek areas of parameter space where this ratio differs significantly from unity.   the assumption that cosmic rays sample the mean density holds over much of parameter space ; however, this assumption begins to break down for high cloud density, injection close to the clouds, and a very tangled magnetic field.   we conclude by evaluating the extent to which our simulated starburst region behaves as a proton calorimeter and constructing the time - dependent spectrum of a burst of cosmic rays.
for amorphous carbon several laboratory extinction data are available, which show quite a wide range of differences due to the structural complexity of this material.   we have calculated self - consistent dynamic models of circumstellar dust - shells around carbon - rich asymptotic giant branch stars, based on a number of these data sets.   the structure and the wind properties of the dynamical models are directly influenced by the different types of amorphous carbon. in our test models   the mass loss is not severely dependent on the difference in the optical properties of the dust, but the influence on the degree of condensation and the final outflow velocity is considerable.   furthermore, the spectral energy distributions and colours resulting from the different data show a much wider spread than the variations within the models due to the variability of the star.   silicon carbide was also considered in the radiative transfer calculations to test its influence on the spectral energy distribution.
an increasing number of individuals are turning to direct - to - consumer ( dtc ) genetic testing to learn about their predisposition to diseases, traits, and/or ancestry.   dtc companies like 23andme and ancestry.com have started to offer popular and affordable ancestry and genealogy tests, with services allowing users to find unknown relatives and long - distant cousins.   naturally, access and possible dissemination of genetic data prompts serious privacy concerns, thus motivating the need to design efficient primitives supporting private genetic tests. in this paper, we present an effective protocol for privacy - preserving genetic relatedness test ( ppgrt ), enabling a cloud server to run relatedness tests on input an encrypted genetic database and a test facility s encrypted genetic sample.   we reduce the test to a data matching problem and perform it, `` privately '', using searchable encryption.   finally, a performance evaluation of hamming distance based pp - grt attests to the practicality of our proposals.
ultraluminous x - ray sources ( ulxs ) are accreting black holes that may contain the missing population of intermediate mass black holes or reflect super - eddington accretion physics.   ten years of _ chandra _ and _ xmm - newton _ observations of ulxs, integrated by multiband studies of their counterparts, have produced a wealth of observational data and phenomenological classifications.   we review the properties of their host galaxies, list popular spectral models and implications for standard and supercritical accretion physics, demonstrate how x - ray timing of these objects places constraints on their masses.   we also review multiwavelength studies of ulxs, including the optical emission of the binary system and nebulosity around them.   we summarize that three classes of black holes could power ulxs : normal stellar mass black holes ( @xmath0  @xmath1 ), massive stellar black holes ( @xmath2  @xmath1 ), and intermediate mass black holes ( @xmath3@xmath4  @xmath1 ). we collect evidence for the presence of these three types of compact objects, including caveat of each interpretation, and briefly review their formation processes.   ultraluminous x - ray sources, ultrapowerful sources, intermediate mass black holes, super - eddington accretion, slim disk.
massive open online courses are an exciting new avenue for instruction and research, yet they are full of unknowns. in the spring of 2013,   mitx released its first introductory physics mooc through the edx platform, generating a total enrollment of 43,000 students from around the world.   we describe the population of participants in terms of their age, gender, level of education, and country of origin, highlighting both the diversity of 8.02x enrollees as well as gender gap and retention. using three midterm exams and the final as waypoints, we highlight performance by different demographic subpopulations and their retention rates.   our work is generally aimed at making a bridge between available mooc data and topics associated with the physics education research community.   address = department of physics@xmath0, office of digital learning@xmath1, research laboratory for electronics@xmath2, electrical engineering and computer science@xmath3, massachusetts institute of technology, cambridge, ma 02139.
we consider a model of dbi inflation where two stacks of mobile branes are moving ultra relativistically in a warped throat.   the stack closer to the tip of the throat is annihilated with the background anti - branes while inflation proceeds by the second stack.   the effects of branes annihilation and particles creation during dbi inflation on the curvature perturbations power spectrum and the scalar spectral index are studied.   we show that for super - horizon scales, modes which are outside the sound horizon at the time of branes collision, the spectral index has a shift to blue spectrum compared to the standard dbi inflation. for small scales   the power spectrum approaches to its background dbi inflation value with the decaying superimposed oscillatory modulations.
the presence of a substantial number of hot stars in the _ extremely metal - rich _ open cluster ngc6791 has been a mystery. if these hot stars are in their core helium burning phase, they are significantly bluer ( hotter ) than predicted by canonical stellar evolution theory. no obvious explanation is available yet.   we consider the effects of mass loss _ during the evolution of horizontal branch _ ( hb )   stars as their possible origin.   we find that the addition of mass loss causes hb stars to evolve to be _   hotter _ and _ fainter_. mass loss has a more pronounced effect for less massive stars and thus naturally widens the temperature ( and color ) distribution on the hb.   if mass loss rates are higher for more metal - rich stars, this phenomenon would be even more pronounced in the metal - rich populations, such as ngc6791.   we find that mass loss on the hb may be a viable method of forming subdwarf b ( sdb ) stars both in the field and in clusters, especially when the metallicity is high.
we present our new scheme for the classification of radial stellar surface brightness profiles for disk galaxies.   we summarize the current theoretical attempts to understand their origin and give an example of an application by comparing local galaxies with their counterparts at high redshift ( @xmath0 ). +
the broad band x - ray spectrum of the low - mass x - ray binary ( lmxb )  was measured with the narrow - field instruments on _ bepposax _ on april 6 and 7, 1997.   the spectrum is consistent with the comptonization of a 0.6  kev thermal spectrum by a hot cloud of temperature equivalent @xmath0  kev. during the observation two type i x - ray bursts   were detected. from the bursts   an upper limit to the distance could be derived of 8  kpc.   combined with an elsewhere determined lower limit of 4  kpc this implies a persistent x - ray luminosity between @xmath1 and @xmath2  which is fairly typical for a lmxb x - ray burster. the accurate determination of the energetics of the two bursts and the persistent emission confirm results with the wide field cameras on _ bepposax _ in a narrower bandpass ( ubertini et al.   1999 ).   comparison with independent x - ray measurements taken at other times indicates that  since its turn - on in 1988 is a rather stable accretor, which is in line with the strong regularity of type i x - ray bursts.
we develop a systematic theory of quantum fluctuations in the driven parametric oscillator ( opo ), including the region near threshold.   this allows us to treat the limits imposed by nonlinearities to quantum squeezing and noise reduction, in this non - equilibrium quantum phase - transition.   in particular, we compute the squeezing spectrum near threshold, and calculate the optimum value.   we find that the optimal noise reduction occurs at different driving fields, depending on the ratio of damping rates.   the largest spectral noise reductions are predicted to occur with a very high - q second - harmonic cavity.   our analytic results agree well with stochastic numerical simulations.   we also compare the results obtained in the positive - p representation, as a fully quantum mechanical calculation, with the truncated wigner phase space equation, also known as semiclassical theory. +   pacs numbers : 03.65.bz
a system is considered, which is subject to external and possibly fatal shocks, with dependence between the fatality of a shock and the system age. apart from these shocks  , the system suffers from competing soft and sudden failures, where soft failures refer to the reaching of a given threshold for the degradation level, and sudden failures to accidental failures, characterized by a failure rate. a non - fatal shock increases both degradation level and failure rate of a random amount, with possible dependence between the two increments.   the system reliability is calculated by four different methods.   conditions under which the system lifetime is new better than used are proposed.   the influence of various parameters of the shocks environment on the system lifetime is studied.   * keywords : * reliability ; bivariate non homogeneous compound poisson process ; hazard rate process ; poisson random measure ; stochastic order ; ageing properties ; two - component series system.    * ams msc : * 60k10 & 60g51
genome sizes have evolved to vary widely, from 250 bases in viroids to 670 billion bases in amoeba.   this remarkable variation in genome size is the outcome of complex interactions between various evolutionary factors such as point mutation rate, population size, insertions and deletions, and genome editing mechanisms that may be specific to certain taxonomic lineages.   while comparative genomics analyses have uncovered some of the relationships between these diverse evolutionary factors, we still do not understand what drives genome size evolution.   specifically, it is not clear how primordial mutational processes of base substitutions, insertions, and deletions influence genome size evolution in asexual organisms. here  , we use digital evolution to investigate genome size evolution by tracking genome edits and their fitness effects in real time. in agreement with empirical data,   we find that mutation rate is inversely correlated with genome size in asexual populations.   we show that at low point mutation rate, insertions are significantly more beneficial than deletions, driving genome expansion and acquisition of phenotypic complexity.   conversely, high mutational load experienced at high mutation rates inhibits genome growth, forcing the genomes to compress genetic information.   our analyses suggest that the inverse relationship between mutation rate and genome size is a result of the tradeoff between evolving phenotypic innovation and limiting the mutational load.
we derive the steady state solution of the fokker - planck equation that describes the dynamics of the nondegenerate optical parametric oscillator in the truncated wigner representation of the density operator.   we assume that the pump mode is strongly damped, which permits its adiabatic elimination.   when the elimination is correctly executed, the resulting stochastic equations contain multiplicative noise terms, and do not admit a potential solution.   however, we develop an heuristic scheme leading to a satisfactory steady - state solution. this provides a clear view of the intracavity two - mode entangled state valid in all operating regimes of the opo.   a nongaussian distribution is obtained for the above threshold solution.
we shall first discuss motivation for higher dimension even for classical description of gravitational dynamics and then construct a black hole out of an anti - desitter ( ads ) spacetime by prescribing a coupling between gauss - bonnet parameter, constant curvature of extra dimensional space and @xmath0.   this is a creation of pure curvature which establishes the fundamental reciprocity between matter and gravity / curvature.
several major milestones and discoveries were attained during the lifetime of the tevatron proton - antiproton collider at fermilab, from 1987 to 2011.   one of the most important was the discovery of the top quark in 1995, followed by an intense program to study that particle in greater detail. in this article  , i give an overview of the history of the top quark, its current status as well as the still to be completed legacy measurements at the tevatorn.   
the possibility of an alternative way to formulate the hawking radiation in a static schwarzschild spacetime has been explored. to calculate the hawking radiation, there can be two possible choices of the spacetime wedge pairs in the krucal - szekeres coordinates.   one is the wedge pair consists of exterior spacetime of a black hole and the exterior spacetime of a white hole, and the other is that of exterior and interior spacetimes of one black hole. the radiation from the former is the hawking s original one.   though the the latter has been often regarded as the same phenomena as the former, the result here suggests it is not ; its radiation has a temperature twice as high as the hawking temperature.   04.62.+v, 04.70.dy
weak gravitational lensing by intervening large - scale structure induces a distinct signature in the cosmic microwave background ( cmb ) that can be used to reconstruct the weak - lensing displacement map.   estimators for individual fourier modes of this map can be combined to produce an estimator for the lensing - potenial power spectrum.   the naive estimator for this quantity will be biased upwards by the uncertainty associated with reconstructing individual modes ; we present an iterative scheme for removing this bias.   the variance and covariance of the lensing - potenial power spectrum estimator are calculated and evaluated numerically in a @xmath0cdm universe for planck and future polarization - sensitive cmb experiments.
we present a novel monte - carlo implementation of dynamic colour screening via multiple exchanges of semi - soft gluons as a basic qcd mechanism to understand diffractive electron - proton scattering at the hera collider. based on the kinematics of individual events in the standard qcd description of deep inelastic scattering at the parton level, which at low @xmath0 is dominantly gluon - initiated  , the probability is evaluated for additional exchanges of softer gluons resulting in an overall colour singlet exchange leading to a forward proton and a rapidity gap as the characteristic observables for diffractive scattering.   the probability depends on the impact parameter of the soft exchanges and varies with the transverse size of the hard scattering subsystem and is therefore influenced by different qcd effects.   we account for matrix elements and parton shower evolution either via conventional dglap @xmath1-evolution with collinear factorisation or ccfm small-@xmath0 evolution with @xmath2-factorisation and discuss the sensitivity to the gluon density distribution in the proton and the importance of large log@xmath0-contributions.   the overall result is that, with only two model parameters which have theoretically motivated values, a satisfactory description of the observed diffractive cross - section at hera is obtained in a wide kinematical range.   lu tp 15 - 51 + april 2016 1.5 cm
we search for isolated galaxies using a volume - limited sample of galaxies with @xmath0 from sdss dr7 supplemented by bright galaxies. we devise a diagnostic tool to select isolated galaxies in different environments using the projected separation ( @xmath1 ) normalized by the virial radius of the nearest neighbor ( @xmath2 ) and the local background density.   we find that the isolation condition of @xmath3 and @xmath4 well segregates the cig galaxies.   we confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.
we discuss the x - ray properties of the cooling flows in a sample of thirty highly x - ray luminous clusters of galaxies observed with the asca and rosat satellites.   we demonstrate the need for multiphase models to consistently explain the spectral and imaging x - ray data for the clusters.   the mass deposition rates of the cooling flows, independently determined from the asca spectra and rosat images, exhibit good agreement and exceed 1000  in the largest systems.   we confirm the presence of intrinsic x - ray absorption in the clusters using a variety of spectral models.   the measured equivalent hydrogen column densities of absorbing material are sensitive to the spectral models used in the analysis, varying from average values of a few @xmath0  for a simple isothermal emission model, to a few @xmath1  using our preferred cooling flow models, assuming in each case that the absorber lies in a uniform foreground screen.   the true intrinsic column densities are likely to be even higher if the absorbing medium is distributed throughout the clusters.   we summarize the constraints on the nature of the x - ray absorber from observations in other wavebands.   a significant part of the x - ray absorption may be due to dust.    # 1to 0pt#1 = " 2218 # 1 # 1    to size    # 1    to size       = cmr10 scaled2 = cmbx10 scaled2 = cmti10 scaled2 ps.   galaxies : clusters : general  cooling flows  intergalactic medium  x - rays : galaxies
a new description of the binary fluid problem via the lattice boltzmann method is presented which highlights the use of the moments in constructing two equilibrium distribution functions.   this offers a number of benefits, including better isotropy, and a more natural route to the inclusion of multiple relaxation times for the binary fluid problem.   in addition, the implementation of solid colloidal particles suspended in the binary mixture is addressed, which extends the solid - fluid boundary conditions for mass and momentum to include a single conserved compositional order parameter.   a number of simple benchmark problems involving a single particle at or near a fluid - fluid interface are undertaken and show good agreement with available theoretical or numerical results.
the standard method of modelling axisymmetric stellar systems begins from the assumption that mass follows light.   the gravitational potential is then derived from the luminosity distribution, and the unique two - integral distribution function @xmath0 that generates the stellar density in this potential is found.   it is shown that the gravitational potential can instead be generated directly from the velocity data in a two - integral galaxy, thus allowing one to drop the assumption that mass follows light.   the two - dimensional rotational velocity field can also be recovered in a model - independent way. regularized algorithms for carrying out the inversions are presented and tested by application to pseudo - data from a family of oblate models.   rutgers astrophysics preprint series no.
we empirically investigated the effects of market factors on the information flow created from @xmath0 linkage relationships among stocks.   we also examined the possibility of employing the minimal spanning tree ( mst ) method, which is capable of reducing the number of links to @xmath1. we determined that market factors carry important information value regarding information flow among stocks.   moreover, the information flow among stocks evidenced time - varying properties according to the changes in market status. in particular, we noted that the information flow increased dramatically during periods of market crises.   finally, we confirmed, via the mst method, that the information flow among stocks could be assessed effectively with the reduced linkage relationships among all links between stocks from the perspective of the overall market.
we derive the sum rule for the spectral function of the stress - energy tensor in the bulk ( uniform dilatation ) channel in a general class of strongly coupled field theories.   this class includes theories holographically dual to a theory of gravity coupled to a single scalar field, representing the operator of the scale anomaly. in the limit when the operator becomes marginal  , the sum rule coincides with that in qcd. using the holographic model,   we verify explicitly the cancellation between large and small frequency contributions to the spectral integral required to satisfy the sum rule in such qcd - like theories.
we study spatio - temporal pattern formation in a ring of @xmath0 oscillators with inhibitory unidirectional pulselike interactions.   the attractors of the dynamics are limit cycles where each oscillator fires once and only once.   since some of these limit cycles lead tothe same pattern, we introduce the concept of pattern degeneracy to take it into account.   moreover, we give a qualitative estimation of the volume of the basin of attraction of each pattern by means of some probabilistic arguments and pattern degeneracy, and show how are they modified as we change the value of the coupling strength. in the limit of small coupling, our estimative formula gives a perfect agreement with numerical simulations.   = msbm10 # 1
in this study, we obtain the size distribution of voids as a @xmath0-parameter redshift independent log - normal void probability function ( vpf ) directly from the cosmic void catalog ( cvc ).   although many statistical models of void distributions are based on the counts in randomly placed cells, the log - normal vpf that we here obtain is independent of the shape of the voids due to the parameter - free void finder of the cvc.   we use three void populations drawn from the cvc generated by the halo occupation distribution ( hod ) mocks which are tuned to three mock sdss samples to investigate the void distribution statistically and the effects of the environments on the size distribution. as a result  , it is shown that void size distributions obtained from the hod mock samples are satisfied by the @xmath0-parameter log - normal distribution.   in addition, we find that there may be a relation between hierarchical formation, skewness and kurtosis of the log - normal distribution for each catalog.   we also show that the shape of the @xmath0- parameter distribution from the samples is strikingly similar to the galaxy log - normal mass distribution obtained from numerical studies.   this similarity of void size and galaxy mass distributions may possibly indicate evidence of nonlinear mechanisms affecting both voids and galaxies, such as large scale accretion and tidal effects. considering in this study   all voids are generated by galaxy mocks and show hierarchical structures in different levels, it may be possible that the same nonlinear mechanisms of mass distribution affect the void size distribution.
we consider a two - particle system in which a particle is held fixed, and the other one rotates around the axis perpendicular to the line joining the particles centers.   the rotating particle leads to a displacement of its polarization charge on the surface.   our results show that the rotational motion of the particles generally reduces the force between the particles.   the dependence of interparticle force on the angular velocity of rotation will be discussed.
we propose a new model for the initiation of a solar coronal mass ejection ( cme ).   the model agrees with two properties of cmes and eruptive flares that have proved to be very difficult to explain with previous models.   a ) very low - lying magnetic field lines, down to the photospheric neutral line, can open toward infinity during an eruption.   b ) the eruption is driven solely by magnetic free energy stored in a closed, sheared arcade ; consequently, the magnetic energy of the closed state is well above that of the post - eruption open state.   the key new feature of our model is that cmes occur in multi - polar topologies, in which reconnection between a sheared arcade and neighboring flux systems triggers the eruption. in this `` magnetic breakout ''   model, reconnection removes the unsheared field above the low - lying, sheared core flux near the neutral line, thereby allowing this core flux to burst open.   we present numerical simulations which demonstrate that our model can account for the energy requirements for cmes.   we discuss the implication of the model for cme / flare prediction.
synthetic bio - molecular spiders with `` legs '' made of single - stranded segments of dna can move on a surface which is also covered by single - stranded segments of dna complementary to the leg dna. in experimental realizations, when a leg detaches from a segment of the surface for the first time it alters that segment, and legs subsequently bound to these altered segments more weakly.   inspired by these experiments we investigate spiders moving along a one - dimensional substrate, whose legs leave newly visited sites at a slower rate than revisited sites. for a random walk ( one - leg spider )   the slowdown does not effect the long time behavior. for a bipedal spider  , however, the slowdown generates an effective bias towards unvisited sites, and the spider behaves similarly to the excited walk.   surprisingly, the slowing down of the spider at new sites increases the diffusion coefficient and accelerates the growth of the number of visited sites.
the arecibo h  i  strip survey probed the halos of @xmath0300 cataloged galaxies and the environments of @xmath014 groups with sensitivity to neutral hydrogen masses @xmath1.   the survey detected no objects with properties resembling the high velocity clouds ( hvcs ) associated with the milky way or local group.   if the hvcs were typically @xmath2 objects distributed throughout groups and galaxy halos at distances of @xmath01  mpc, the survey should have made @xmath070 hvc detections in groups and @xmath0250 detections around galaxies.   the null detection implies that hvcs are deployed at typical distances of @xmath3200  kpc from the galaxies or group barycenters.   if the clouds are in virial equilibrium, their average dark matter fraction must be 98% or higher.
we report new observations of the unusually active, high proper motion l5e dwarf 2mass j13153094@xmath02649513. optical spectroscopy with   magellan / mage reveals persistent nonthermal emission, with narrow h  i balmer, na  i and k  i lines all observed in emission. low - resolution near - infrared spectroscopy with irtf / spex indicates the presence of a low - temperature companion, which is resolved through multi - epoch laser guide star adaptive optics imaging at keck.   the comoving companion is separated by 338@xmath14  mas, and its relative brightness ( @xmath2 = 5.09@xmath10.10 ) makes this system the second most extreme flux ratio very low - mass binary identified to date  . resolved near - infrared spectroscopy with keck / osiris identifies this companion as a t7 dwarf.   the absence of li  i absorption in combined - light optical spectroscopy constrains the system age to @xmath30.81.0  gyr, while the system s kinematics and unusually low mass ratio ( m@xmath4/m@xmath5 = 0.30.6 ) suggests that it is even older.   a coevality test of the components also indicates an older age, but reveals discrepancies between evolutionary and atmosphere model fits of the secondary which are likely attributable to poor reproduction of its near - infrared spectrum. with a projected separation of 6.6@xmath10.9  au,   the 2mass  j1315@xmath02649 system is too widely separated for mass exchange or magnetospheric interactions to be powering its persistent nonthermal emission.   rather, the emission is probably chromospheric in nature, signaling an inversion in the age - activity relation in which strong magnetic fields are maintained by relatively old and massive ultr
this paper presents a theoretical study of oscillatory and rotational instabilities of a solid spherical body levitated electromagnetically in axisymmetric coils made of coaxial circular loops.   we apply our previous theory to analyze the static and dynamic stability of the sample depending on the ac frequency and the position of the sample in the coils for several simple configurations.   an original analytical approach is introduced employing a gauge transformation for the vector potential.   first we calculate the spring constants which define the frequency of small - amplitude oscillations. for static stability the spring   constants must be positive.   dynamic instabilities are characterized by critical ac frequencies which, when exceeded, may result either in a spin - up or oscillations with increasing amplitude.   it is found that the critical frequencies increase with the non - uniformity of the field.   we show that for a spherically harmonic field the critical frequency for the spin - up instability in a field of degree @xmath0 coincides with the critical frequency for the oscillatory instability in a field of degree @xmath1.
we examine phantom dark energy models derived from a scalar field with a negative kinetic term for which @xmath0 asymptotically.   all such models can be divided into three classes, corresponding to an equation of state parameter @xmath1 with asymptotic behavior @xmath2, @xmath3, and @xmath4.   we derive the conditions on the potential @xmath5 which lead to each of these three types of behavior. for models with @xmath2  , we derive the conditions on @xmath5 which determine whether or not such models produce a future big rip.   observational constraints are derived on two classes of these models : power - law potentials with @xmath6 ( with @xmath7 positive or negative ) and exponential potentials of the form @xmath8.   it is shown that these models spend more time in a state with @xmath9 than do corresponding models with a constant value of @xmath1, thus providing a more satisfactory solution to the coincidence problem.
thermal fits have consistently reproduced the experimental particles yields of heavy ion collisions, however, the proton to pion ratio from alice pb+pb @xmath0 tev is over - predicted by thermal models- known at the @xmath1 puzzle.   here we test the relevance of the extended mass spectrum, i.e., include hagedorn states ( resonances that follow an exponential mass spectrum and have very short life times ) on the @xmath1 puzzle.   we find that the extended mass spectrum is able to reproduce particle ratios at both rhic and the lhc as well as being able to match the lower @xmath1 ratio at the lhc through dynamical chemical equilibration.   hadron resonance gas, relativistic heavy - ion collisions, extended mass spectrum, hagedorn states, dynamical hadronic interations, thermal fits
daily temperature anomaly records are analyzed ( 61 for australia, 18 for hungary ) by means of detrended fluctuation analysis.   positive long range asymptotic correlations extending up to 5 - 10 years are detected for each case.   contrary to earlier claims, the correlation exponent is not universal for continental stations.   interestingly, the dominant factor is geographic latitude over australia : the general tendency is a decrease of correlation exponent with increasing distance from the equator.   this tendency is in a complete agreement with the results found by tsonis et al.   ( 1999 ) for 500-hpa height anomalies in the northern hemisphere.   the variance of fluctuations exhibits an opposite trend, the larger is the distance from the equator, the larger the amplitude of intrinsic fluctuations.   the presence of tropospheric biennial oscillation is clearly identified for three stations at the north - eastern edge of the australian continent.
we present near - infrared spectroscopy of a sample of 22 extreme emission line galaxies at redshifts @xmath0, confirming that these are low - mass ( @xmath1 ) galaxies undergoing intense starburst episodes ( @xmath2 10 @xmath3 100 myr ).   the sample is selected by  or @xmath4 emission line flux and equivalent width using near - infrared grism spectroscopy from the 3d - hst survey.   high - resolution nir spectroscopy is obtained with lbt / luci and vlt / x - shooter.   the /@xmath5 line ratio is high ( @xmath6 ) and /h@xmath7 is always significantly below unity, which suggests a low gas - phase metallicity.   we are able to determine gas - phase metallicities for 7 of our objects using various strong - line methods, with values in the range 0.05 @xmath3 0.30 @xmath8 and with a median of 0.15 @xmath8 ; for 3 of these objects we detect @xmath94363 which allows for a direct constraint on the metallicity.   the velocity dispersion, as measured from the nebular emission lines, is typically @xmath10.   combined with the observed star - forming activity, the jeans and toomre stability criteria imply that the gas fraction must be large ( @xmath11 2/3 ), consistent with the difference between our dynamical and stellar mass estimates.   the implied gas depletion time scale ( several hundred myr ) is substantially longer than the inferred mass - weighted ages ( @xmath1250 myr ), which further supports the emerging picture that most stars in low - mass galaxies form in short, intense bursts of star formation.
we follow the bright, highly energetic afterglow of _ swift_-discovered grb080721 at @xmath0 out to 36 days or 3@xmath110@xmath2  s since the trigger in the optical and x - ray bands.   we do not detect a break in the late - time light curve inferring a limit on the opening angle of @xmath3 and setting tight constraints on the total energy budget of the burst of @xmath4 erg within the fireball model. to obey the fireball model closure relations   the grb jet must be expanding into a homogeneous surrounding medium and likely lies behind a significant column of dust.   the energy constraint we derive can be used as observational input for models of the progenitors of long gamma - ray bursts : we discuss how such high collimation - corrected energies could be accommodated with certain parameters of the standard massive star core - collapse models.   we can, however, most probably rule out a magnetar progenitor for this grb which would require 100% efficiency to reach the observed total energy.       gamma - rays : bursts
i report on the observation of electroweak production of single top quarks in  collisions at @xmath0 using @xmath1 of data collected with the d0 detector at the fermilab tevatron collider. using events containing an isolated electron or muon, missing transverse energy, two, three or four jets, with one or two of them identified as originating from the fragmentation of a @xmath2 quark, the measured cross section for the process @xmath3 is @xmath4  pb ( for a top quark mass of @xmath5 ). the probability to measure a cross section at this value or higher in the absence of signal is @xmath6, corresponding to a 5.0  standard deviation significance.   using the same dataset, the measured cross sections for the @xmath7- and the @xmath8-channel processes when determined simultaneously with no assumption on their relative production rate are @xmath9  pb and @xmath10  pb respectively, consistent with standard model expectations.   the measured @xmath7-channel cross section has a significance of 4.8 standard deviations, representing the first evidence for the production of an individual single top process to be detected.   = 5 = 5    0d 0draft    0d
a combined theoretical and experimental study reveals evidence for the dual topological insulating character of the stoichiometric natural superlattice phase @xmath0_{1}_{2}}$ ], being a stack of alternating bi bilayers and two quintuple layers of @xmath1.   we identify @xmath2 by density functional theory to exhibit a non trivial time - reversal symmetry - driven character of @xmath3 and additionally a mirror - symmetry induced mirror chern number of @xmath4, which indicates that @xmath2 is both a weak topological insulator and a topological crystalline insulator.   the coexistence of the two phenomena preordains distinct crystal planes to host topological surface states that are protected by the respective symmetries.   the surface perpendicular to the stacking direction is the dark surface of the weak topological insulator, while hosting mirror - symmetry protected surface states along the @xmath5 direction at non - time - reversal invariant momenta points.   we confirm the stacking sequence of our mbe - grown @xmath2 thin films by x - ray diffraction and transmission electron microscopy, and find indications of the topological crystalline and weak topological character in the surface electronic spin structure by spin- and angle - resolved photoemission spectroscopy, which nicely match the results from density functional theory.
we derive the mass - radius relation of relativistic white dwarf stars ( modeled as a self - gravitating degenerate fermi gas at @xmath0 ) in a @xmath1-dimensional universe and study the influence of the dimension of space on the laws of physics when we combine quantum mechanics, special relativity and gravity.   we exhibit characteristic dimensions @xmath2, @xmath3, @xmath4, @xmath5, @xmath6, @xmath7 and show that quantum mechanics can not balance gravitational collapse for @xmath8.   this is similar to a result found by ehrenfest ( 1917 ) at the atomic level for coulomb forces ( in bohr s model ) and for the kepler problem.   this makes the dimension of our universe @xmath4 very particular with possible implications regarding the anthropic principle.   we discuss some historic aspects concerning the discovery of the chandrasekhar ( 1931 ) limiting mass in relation to previous investigations by anderson ( 1929 ) and stoner ( 1930 ).   we also propose different derivations of the stability limits of polytropic distributions and consider their application to classical and relativistic white dwarf stars.
a bit - string model for the evolution of a population of haploid organisms, subject to competition, reproduction with mutation and selection is studied, using mean field theory and monte carlo simulations.   we show that, depending on environmental flexibility and genetic variability, the model exhibits a phase transtion between extinction and survival.   the mean - field theory describes the infinite - size limit, while simulations are used to study quasi - stationary properties.   @xmath0 email address : kathia@escelsa.com.br + @xmath1 email address : dickman@fisica.ufmg.br + @xmath2 email address : atb@iceb.ufop.br +    1em.8em -.5 cm
the effective interaction between two planar walls immersed in a fluid is investigated by use of density functional theory in the region of the phase diagram. a hard core yukawa model of fluid   is studied with special attention to the critical region. to achieve this goal a new formulation of the weighted density approximation coupled with the hierarchical reference theory, able to deal with critical long wavelength fluctuations, is put forward and compared with other approaches. the effective interaction between the walls   is seen to change character on lowering the temperature : the strong oscillations induced by layering of the molecules, typical of the depletion mechanism in hard core systems, are gradually smoothed and, close to the critical point, a long range attractive tail emerges leading to a scaling form which agrees with the expectations based on the critical casimir effect.   strong corrections to scaling are seen to affect the results up to very small reduced temperatures. by use of derjaguin approximation, this investigation has natural implications for the aggregation of colloidal particles in critical solvents.
the two papers referred to in the title, claiming the detection of a large - scale massive hot gaseous halo around the galaxy, have generated a lot of confusion and unwarranted excitement ( including public news coverage ).   however, the papers are seriously flawed in many aspects, including problematic analysis and assumptions, as well as mis - reading and mis - interpreting earlier studies, which are inconsistent with the claim. here   we show examples of such flaws.   x - rays : individual : lmc x-3, mrk 421, 4u 1957 + 11, x - rays : ism
the observation of the polarization emerging from a rotating star at different phases opens up the possibility to map the magnetic field in the stellar surface thanks to the well - known zeeman doppler imaging.   when the magnetic field is sufficiently weak, the circular and linear polarization profiles locally in each point of the star are proportional to the first and second derivatives of the unperturbed intensity profile, respectively.   we show that the weak - field approximation ( for weak lines in the case of linear polarization ) can be generalized to the case of a rotating star including the doppler effect and taking into account the integration on the stellar surface.   the stokes profiles are written as a linear combination of wavelength - dependent terms expressed as series expansions in terms of hermite polynomials.   these terms contain the surface integrated magnetic field and velocity components.   the direct numerical evaluation of these quantities is limited to rotation velocities not larger than 8 times the doppler width of the local absorption profiles.   additionally, we demonstrate that, in a rotating star, the circular polarization flux depends on the derivative of the intensity flux with respect to the wavelength and also on the profile itself. likewise, the linear polarization depends on the profile and on its first and second derivative with respect to the wavelength.   we particularize the general expressions to a rotating dipole.
we obtain a semiclassical expression for the projector onto eigenfunctions by means of the fredholm theory.   we express the projector in the coherent state basis, thus obtaining the semiclassical husimi representation of the stadium eigenfunctions, which is written in terms of classical invariants : periodic points, their monodromy matrices and maslov indices.   pacs numbers : 05.45.+b, 03.65.sq, 03.40.kf    20.5 cm 1.5 cm
among various phenomenological @xmath0 models, a time - dependent model @xmath1 is selected here to investigate the @xmath0-cdm cosmology.   the model can follow from dynamics, underlying the origin of @xmath0. using this model the expressions for the time - dependent equation of state parameter @xmath2 and other physical parameters   are derived.   it is shown that in @xmath3 model accelerated expansion of the universe takes place at negative energy density, but with a positive pressure.   it has also been possible to obtain the change of sign of the deceleration parameter @xmath4 during cosmic evolution.   example.eps    gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
we report the first detection of gas - phase co@xmath0 emission in the star - forming region cepheus a east, obtained by spectral line mapping of the @xmath1 bending mode at 14.98 @xmath2 m with the infrared spectrograph ( irs ) instrument onboard the _ spitzer space telescope_. the gaseous co@xmath0 emission covers a region about 35@xmath3 @xmath4 25@xmath3 in extent, and results from radiative pumping by 15 @xmath2 m continuum photons emanating predominantly from the hw2 protostellar region.   the gaseous co@xmath0 exhibits a temperature distribution ranging from 50 k to 200 k. a correlation between the gas - phase co@xmath0 distribution and that of h@xmath0 s(2 ), a tracer of shock activity, indicates that the co@xmath0 molecules originate in a cool post - shock gas component associated with the outflow powered by hw2.   the presence of co@xmath0 ice absorption features at 15.20 @xmath2 m toward this region and the lack of correlation between the ir continuum emission and the co@xmath0 gas emission distribution further suggest that the gaseous co@xmath0 molecules are mainly sputtered off grain mantles  by the passage of slow non - dissociative shocks with velocities of 15 - 30 km s@xmath5  rather than sublimated through grain heating.
based on a linear and non - linear study of radial pulsations in the envelopes of classical novae ( schenker 1999 ), i discuss the results both from the point of view of pulsation theory as well as their consequences for current nova models.   starting from initially static envelope structures at various stages during the decline of a nova outburst, strong ` running wave'instabilities have been found that rapidly grow into shocks.   improved analytical concepts give a new direction to the interpretation of such highly non - adiabatic radial pulsations. for direct observational confirmation a search for short period variability in the uv and soft x - ray is suggested during the very late decline phase.   speculative consequences for mass loss scenarios in novae due to these instabilities will need some more work in the future.
we calculate the non - linear conductance of a quantum point contact using the non - equilibrium greens function technique within the hartree approximation of spinless electrons.   we quantitative reproduce the 0.25-anomaly  in the differential conductance ( i.e. the lowest plateau at @xmath0 ) as well as an upward bending of higher conductance half - integer plateaus seen in the experiments, and relate these features to the non - linear screening and pinning effects.
we study bifurcations of a three - dimensional diffeomorphism, @xmath0, that has a quadratic homoclinic tangency to a saddle - focus fixed point with multipliers @xmath1, where @xmath2 and @xmath3.   we show that in a three - parameter family, @xmath4, of diffeomorphisms close to @xmath0, there exist infinitely many open regions near @xmath5 where the corresponding normal form of the first return map to a neighborhood of a homoclinic point is a three - dimensional hnon - like map.   this map possesses, in some parameter regions, a  wild - hyperbolic " lorenz - type strange attractor.   thus, we show that this homoclinic bifurcation leads to a strange attractor.   we also discuss the place that these three - dimensional hnon maps occupy in the class of quadratic volume - preserving diffeomorphisms.
we present high - precision photometry of the hypervelocity star sdss j090745.0 + 024507 ( hvs ), which has a galactic rest - frame radial velocity of @xmath0, and so has likely been ejected from the supermassive black hole in the galactic center.   our data were obtained on two nights using the mmt 6.5 m telescope, and is supplemented by lower precision photometry obtained on four nights using the flwo 1.2 m telescope.   the high - precision photometry indicates that the hvs is a short - period, low - amplitude variable, with period @xmath1 and amplitude @xmath2.   together with the known effective temperature of @xmath3 ( spectral type b9 ), this variability implies that the hvs is a member of the class of slowly pulsating b - type main sequence stars, thus resolving the previously - reported two - fold degeneracy in the luminosity and distance of the star.   the hvs has a heliocentric distance of @xmath4, and an age of @xmath5.   the time of ejection from the center of the galaxy is @xmath6 myr, and thus the existence of the os constitutes observational evidence of a population of young stars in the proximity of the central supermassive black hole @xmath7 gyr ago.   it is possible that the hvs was a member of a binary that was tidally disrupted by the central black hole ; we discuss constraints on the properties of the companion s orbit.
using brownian dynamics ( bd ) simulations we investigate a dense system of charged colloids exposed to shear flow in a confined ( slit - pore ) geometry.   the equilibrium system at zero flow consists of three, well - pronounced layers with square - like crystalline in - plane structure.   we demonstrate that, for sufficiently large shear rates, the middle layer separates into two sublayers where the particles organize into moving lanes with opposite velocities. the formation of this micro - laned state results in a destruction of the applied shear profile.   it has a strong impact not only on the structure of the system, but also on its rheology as measured by the stress tensor. at higher shear rates we observe a disordered state and finally a recrystallization   reminiscent of the behavior of bilayer films.   we expect the shear - induced laning to be a generic feature of _ thin _ films with three or more layers.
the structure of static atmospheres around unmagnetized neutron stars undergoing steady, spherical accretion is discussed.   we focus on the `` hot '' configurations presented by turolla et al.   ( 1994 ) and calculate the radiation spectrum using a characteristics method. in particular, it is found that e@xmath0e@xmath1 pair production may affect significantly the external atmospheric layers, where positron and proton number densities become of the same order.   the consequent increase of the scattering opacity lowers the eddington limit and this, in turn, may drive a dynamical instability if the accretion luminosity is large enough, ultimately producing a rapid expulsion of the envelope.   if `` hot '' states are indeed accessible, this mechanism could give rise to transient phenomena in hard x  rays of potential great astrophysical interest.
the photoproduction of quarkonium in coherent hadron - hadron ( @xmath0 ) interactions for lhc energies is an important tool to investigate the qcd dynamics at high energies. in this paper   we estimate the integrated cross section and rapidity distribution for @xmath1 and @xmath2 production using the color glass condensate ( cgc ) formalism.   we predict large rates, implying that the experimental identification could be feasible at the lhc.
with the continuous growth in the consumer markets of mobile smartphones and increasingly in augmented binocular vision wearable devices, several avenues of research investigate the relationships between the quality perceived by mobile users and the delivery mechanisms at play to support a high quality of experience for mobile users. in this paper, we present the first study that evaluates the relationships of mobile movie quality and the viewer  perceived quality thereof in an augmented binocular vision setting employing commercially available head  mounted see  through devices.   we find that participants tend to overestimate the video quality when compared to a scaled representation and exhibit a significant variation of accuracy that leans onto the movie content and its dynamics.   our findings, thus, can broadly impact future media adaptation and delivery mechanisms for this new display format of mobile multimedia and spur follow   up research in this increasingly popular domain.    augmented reality, multimedia systems, perceptual quality, quality of experience, quality of service
embedding of the 5-dimensional ( 5d ) space of the bohr hamiltonian with a deformation - dependent mass ( ddm ) into a 6-dimensional ( 6d ) space shows that the free parameter in the dependence of the mass on the deformation is connected to the curvature of the 5d space, with the special case of constant mass corresponding to a flat 5d space.   comparison of the ddm bohr hamiltonian to the 5d classical limit of hamiltonians of the 6d interacting boson model ( ibm ), shows that the ddm parameter is proportional to the strength of the pairing interaction in the u(5 ) ( vibrational ) symmetry limit, while it is proportional to the quadrupole - quadrupole interaction in the su(3 ) ( rotational ) symmetry limit, and to the difference of the pairing interactions among @xmath0, @xmath1 bosons and @xmath1 bosons alone in the o(6 ) ( @xmath2-soft ) limit.   the presence of these interactions leads to a curved 5d space in the classical limit of ibm, in contrast to the flat 5d space of the original bohr hamiltonian, which is made curved by the introduction of the deformation - dependent mass.   _ keywords _ : bohr collective model, interacting boson model, deformation - dependent mass
turbulent - laminar banded patterns in plane poiseuille flow are studied via direct numerical simulations in a tilted and translating computational domain using a parallel version of the pseudospectral code channelflow.   3d visualizations via the streamwise vorticity of an instantaneous and a time - averaged pattern are presented, as well as 2d visualizations of the average velocity field and the turbulent kinetic energy.   simulations for @xmath0 show the gradual development from uniform turbulence to a pattern with wavelength 20 half - gaps at @xmath1, to a pattern with wavelength 40 at @xmath2 and finally to laminar flow at @xmath3.   these transitions are tracked quantitatively via diagnostics using the amplitude and phase of the fourier transform and its probability distribution.   the propagation velocity of the pattern is approximately that of the mean flux and is a decreasing function of reynolds number.   examination of the time - averaged flow shows that a turbulent band is associated with two counter - rotating cells stacked in the cross - channel direction and that the turbulence is highly concentrated near the walls. near the wall  , the reynolds stress force accelerates the fluid through a turbulent band while viscosity decelerates it ; advection by the laminar profile acts in both directions. in the center  , the reynolds stress force decelerates the fluid through a turbulent band while advection by the laminar profile accelerates it.   these characteristics are compared with those of turbulent - laminar banded patterns in plane couette flow.
we present an interferometric study of the continuum surface of the red supergiant star betelgeuse at 11.15@xmath0 m wavelength, using data obtained with the berkeley infrared spatial interferometer each year between 2006 and 2010.   these data allow an investigation of an optically thick layer within 1.4 stellar radii of the photosphere.   the layer has an optical depth of @xmath11 at 11.15@xmath0 m, and varies in temperature between 1900k and 2800k and in outer radius between 1.16 and 1.36 stellar radii.   electron - hydrogen atom collisions contribute significantly to the opacity of the layer.   the layer has a non - uniform intensity distribution that changes between observing epochs.   these results indicate that large - scale surface convective activity strongly influences the dynamics of the inner atmosphere of betelgeuse, and mass - loss processes.
we consider theoretically thz lasing in a system consisting of a quantum well placed inside an optical microcavity and a thz cavity in the regime of two - photon excitation of 2p dark exciton states.   the stability of the system with varying parameters of the microcavity under coherent pumping is studied.   we show that the nonlinearity provided by two photon absorption can give rise to bistability and hysteresis in the thz output.
we outline a rigorous method which can be used to solve the many - body schrdinger equation for a coulomb interacting electronic system in an external classical magnetic field as well as a quantized electromagnetic field.   effects of the geometry of the electronic system as well as the polarization of the quantized electromagnetic field are explicitly taken into account.   we accomplish this by performing repeated truncations of many - body spaces in order to keep the size of the many particle basis on a manageable level.   the electron - electron and electron - photon interactions are treated in a nonperturbative manner using `` exact numerical diagonalization ''.   our results demonstrate that including the diamagnetic term in the photon - electron interaction hamiltonian drastically improves numerical convergence.   additionally, convergence with respect to the number of photon states in the joint photon - electron fock space basis is fast.   however, the convergence with respect to the number of electronic states is slow and is the main bottleneck in calculations.
this paper presents the recent results from super - kamiokande atmospheric neutrinos and from k2k accelerator neutrinos.   both results show the signal of neutrino oscillation, and provide new and precise information of oscillation parameters.   the oscillation parameters are constraint to be between @xmath0  @xmath1 and @xmath2  @xmath3 for @xmath4 and to be greater than 0.92 for @xmath5.   = 14.5pt
we give two determinantal representations for a bivariate polynomial.   they may be used to compute the zeros of a system of two of these polynomials via the eigenvalues of a two - parameter eigenvalue problem.   the first determinantal representation is suitable for polynomials with scalar or matrix coefficients, and consists of matrices with asymptotic order @xmath0, where @xmath1 is the degree of the polynomial.   the second representation is useful for scalar polynomials and has asymptotic order @xmath2.   the resulting method to compute the roots of a system of two bivariate polynomials is competitive with some existing methods for polynomials up to degree 10, as well as for polynomials with a small number of terms.   system of bivariate polynomial equations, determinantal representation, two - parameter eigenvalue problem, polynomial multiparameter eigenvalue problem.   65f15, 65h04, 65f50, 13p15.
we report on a study of the time sequence for the appearance of high - velocity jets and equatorial tori in the transition of stars from the asymptotic giant branch to the planetary nebulae phase.   jets and tori are prominent features of this evolution, but their origins are uncertain. using the kinematics of molecular tori and molecular or optical jets, we determine the ejection histories for a sample of well - observed cases.   we find that jets and tori develop nearly simultaneously.   we also find evidence that jets appear slightly later than tori, with a typical jet - lag of a few hundred years.   the reconstructed time - lines of this sequence provide good evidence that jets and tori are physically related, and they set new constraints on jet formation scenarios.   some scenarios are ruled out or rendered implausible, and others are challenged at a quantitative level.
pedigrees are directed acyclic graphs that represent ancestral relationships between individuals in a population. based on a schematic recombination process, we describe two simple markov models for sequences evolving on pedigrees - model r ( recombinations without mutations ) and model rm ( recombinations with mutations ). for these models,   we ask an identifiability question : is it possible to construct a pedigree from the joint probability distribution of extant sequences?   we present partial identifiability results for general pedigrees : we show that when the crossover probabilities are sufficiently small, certain spanning subgraph sequences can be counted from the joint distribution of extant sequences.   we demonstrate how pedigrees that earlier seemed difficult to distinguish are distinguished by counting their spanning subgraph sequences.   mathematics subject classifications : primary : 60, 05, secondary : 05c60,92d    keywords : reconstructing pedigrees, identifiability, recombinations, mutations
using direct numerical simulations, the fragmentation of falling liquid droplets in a quiescent media is studied.   three simulations with different e@xmath0tv@xmath0s numbers were performed.   an adaptive volume of fluid ( vof ) method based on octree meshing is used, providing a notable reduction of computational cost.   the current video includes 4 main parts describing the fragmentation of the falling droplet.
we report on a first - principles study of the structure of o / rh(001 ) at half a monolayer of oxygen coverage, performed using density - functional theory.   we find that oxygen atoms sit at the center of the _ black _ squares of a chess - board, @xmath0, pattern.   this structure is unstable against a rhomboid distortion of the _ black _ squares, which shortens the distance between an o atom and two of the four neighboring rh atoms, while lengthening the distance with respect to the other two.   we actually find that the surface energy is further lowered by allowing the o atom to get off the short diagonal of the rhombus so formed.   we predict that the latter distortion is associated with an order - disorder transition, occurring below room temperature.   the above rhomboid distortion of the square lattice may be seen as a rotation of the empty, _ white _, squares.   our findings are at variance with recent claims based on stm images, according to which it is instead the _ black _ squares which would rotate.   we argue that these images are indeed compatible with our predicted reconstruction pattern.   _ keywords : _ chemisorption ; rhodium ; oxygen ; density functional calculations
a new method for removing impulse noise from speech in the wavelet transform domain is proposed.   the method utilizes the multi - resolution property of the wavelet transform, which provides finer time resolution at the higher frequencies than the short - time fourier transform ( stft ), to effectively identify and remove impulse noise.   it uses two features of speech to discriminate speech from impulse noise : one is the slow time - varying nature of speech and the other is the lipschitz regularity of the speech components. on the basis of these features, an algorithm has been developed to identify and suppress wavelet coefficients that correspond to impulse noise.   experiment results show that the new method is able to significantly reduce impulse noise without degrading the quality of the speech signal or introducing any audible artifacts.   wavelets, transient removal, impulsive noise removal, speech enhancement
a cosmic far - infrared background ( cfirb ) has long been predicted that would traces the intial phases of galaxy formation.   it has been first detected by  @xcite using cobe data and has been later confirmed by several recent studies (  @xcite,  @xcite,  @xcite ).   we will present a new determination of the cfirb that uses for the first time, in addition to cobe data, two independent gas tracers : the hi survey of leiden / dwingeloo (  @xcite ) and the wham h@xmath0 survey (  @xcite ).   we will see that the cfirb above 100 @xmath1 m is now very well constrained.   the next step is to see if we can detect its fluctuations. to search for the cfirb fluctuations,   we have used the firback observations.   firback is a deep cosmological survey conducted at 170@xmath1 m with isophot (  @xcite ).   we show that the emission of unresolved extra - galactic sources clearly dominates, at arcminute scales, the background fluctuations in the lowest galactic emission regions.   this is the first detection of the cfirb fluctuations.
background : :    an electron localization measure was originally introduced to    characterize chemical bond structures in molecules. recently, a    nucleon localization based on hartree - fock densities has been    introduced to investigate @xmath0-cluster structures in    light nuclei.   compared to the local nucleonic densities, the nucleon    localization function has been shown to be an excellent indicator of    shell effects and cluster correlations.   purpose : :    using the spatial nucleon localization measure, we investigate the    cluster structures in deformed light nuclei and study the emergence of    fragments in fissioning heavy nuclei. methods   : :    to illustrate basic concepts of nucleon localization, we employ the    deformed harmonic oscillator model.   realistic calculations are carried    out using self - consistent nuclear density functional theory with    quantified energy density functionals optimized for fission studies.   results : :    we study particle densities and spatial nucleon localization    distributions for deformed cluster configurations of    @xmath1be and @xmath2ne, and also along the    fission pathways of @xmath3th and @xmath4pu.   we illustrate the usefulness of the localization measure by showing    how the hyperdeformed state of @xmath3th can be    understood in terms of a quasimolecular state made of    @xmath5sn and @xmath6zr fragments.   conclusions : :    compared to nucleonic distributions, the nucleon localization function    more effectively quantifies nucleonic clustering in light and heavy    nuclei : its characteristic oscillating pattern, traced back to shell    effects,
we use new and published medium resolution 0.62.5  @xmath0 m spectra of l and t dwarfs to develop a unified classification system for both of these new spectral classes.   two indices of the system at 1.2  @xmath0 m and 1.5  @xmath0 m are based on nearby absorption bands of water vapor and two are associated with methane bands near 1.6  @xmath0 m and 2.2  @xmath0 m.   the 1.5  @xmath0 m index is monotonic through the l and t sequences, and forms the backbone of the system ; the indices for the other bands provide extensive, but only partial, coverage.   we correlate the 1.5  @xmath0 m index with continuum indices shortward of 1  @xmath0 m devised by others for classifying l dwarfs, in order to obtain a tight link between optical and infrared classifications.   our proposed system defines ten spectral subclasses for l ( l0l9 ) and nine for t ( t0t8 ).   the boundary between l and t is defined to be the onset of absorption by methane in the h band.   methane absorption in the k band near 2.2  @xmath0 m is found to begin approximately at l8.
ion current fluctuations occurring within open and closed states of large conductance locust potassium channel ( bk channel ) were investigated for the existence of correlation.   both time series, extracted from the ion current signal, were studied by the autocorrelation function ( afa ) and the detrended fluctuation analysis ( dfa ) methods.   the persistent character of the short- and middle - range correlations of time series is shown by the slow decay of the autocorrelation function.   the dfa exponent @xmath0 is significantly larger than 0.5.   the existence of strongly - persistent long - range correlations was detected only for closed - states fluctuations, with @xmath1.   the long - range correlation of the bk channel action is therefore determined by the character of closed states.   the main outcome of this study is that the memory effect is present not only between successive conducting states of the channel but also independently within the open and closed states themselves.   as the ion current fluctuations give information about the dynamics of the channel protein, our results point to the correlated character of the protein movement regardless whether the channel is in its open or closed state.   _ pacs : _ 87.17.-d, 05.40.+j + _ keywords : _ ionic current, bk channel, detrended fluctuation analysis, autocorrelation function
in a previous letter [ phys.   rev.  lett.   * 96 *, 123401 ( 2006 ) ] we have shown by means of three - dimensional particle - in - cell simulations and a simple rigid - sphere model that nonlinear resonance absorption is the dominant collisionless absorption mechanism in the intense, short - pulse laser cluster interaction. in this paper   we present a more detailed account of the matter.   in particular we show that the absorption efficiency is almost independent of the laser polarization. in the rigid - sphere model, the absorbed energy increases by many orders of magnitude at a certain threshold laser intensity.   the particle - in - cell results display maximum fractional absorption around the same intensity.   we calculate the threshold intensity and show that it is underestimated by the common over - barrier ionization estimate.
we employ three - dimensional state of the art magnetohydrodynamic models of the early solar wind and heliosphere and a two - dimensional model for cosmic ray transport to investigate the cosmic ray spectrum and flux near the archean earth.   we assess how sensitive the cosmic ray spectrum is to changes in the sunspot placement and magnetic field strength, the large scale dipole magnetic field strength, the wind ram pressure, and the sun s rotation period.   overall, our results confirm earlier work that suggested the archean earth would have experienced a greatly reduced cosmic ray flux than is the case today.   the cosmic ray reduction for the early sun is mainly due to the shorter solar rotation period and tighter winding of the parker spiral, and to the different surface distribution of the more active solar magnetic field.   these effects lead to a global reduction of the cosmic ray flux at 1  au by up to two orders of magnitude or more.   variations in the sunspot magnetic field have more effect on the flux than variations in the dipole field component.   the wind ram pressure affects the cosmic ray flux through its influence on the size of the heliosphere via the pressure balance with the ambient interstellar medium.   variations in the interstellar medium pressure experienced by the solar system in orbit through galaxy could lead to order of magnitude changes in the cosmic ray flux at earth on timescales of a few million years.
we present the results and parameterization of the 0.5 - 2 kev luminosity function of agns from various rosat surveys, ranging from the rosat bright survey from the rosat all - sky survey ( rass ) to the ultra - deep survey on the lockman hole. a luminosity - dependent density evolution model, where the density evolution rate drops at low luminosities, gives an excellent parametric description of the overall xlf covering wide ranges of redshift and luminosity.   the number density evolution of high - luminosity agns in our sample shows a similar behavior to optical and radio surveys, except that we do not find evidence for the rapid decrease of the number density at @xmath0.   the discrepancy is marginally significant and including more deep survey results would make better determination of the behavior.
we propose the use of topographic modulation of surfaces to select and localize particles in nematic colloids. by considering convex and concave deformations of one of the confining surfaces we show that the colloid - flat surface repulsion may be enhanced or switched into an attraction.   in particular, we find that when the colloidal particles have the same anchoring conditions as the patterned surfaces, they are strongly attracted to concave dimples, while if they exhibit different anchoring conditions they are pinned at the top of convex protrusions.   although dominated by elastic interactions the first mechanism is reminiscent of the depletion induced attraction or of the key - lock mechanism, while the second is specific to liquid crystal colloids.   these long - ranged, highly tunable, surface - colloid interactions contribute for the development of template - assisted assembly of large colloidal crystals, with well defined symmetries, required for applications.
an efficient algorithm for adaptive kernel smoothing ( aks ) of two - dimensional imaging data has been developed and implemented using the interactive data language ( idl ).   the functional form of the kernel can be varied ( top - hat, gaussian etc. ) to allow different weighting of the event counts registered within the smoothing region.   for each individual pixel the algorithm increases the smoothing scale until the signal - to - noise ratio ( s.n.r. ) within the kernel reaches a preset value.   thus, noise is suppressed very efficiently, while at the same time real structure, i.e.  signal that is locally significant at the selected s.n.r  .  level, is preserved on all scales.   in particular, extended features in noise - dominated regions are visually enhanced.   the asmooth algorithm differs from other aks routines in that it allows a quantitative assessment of the goodness of the local signal estimation by producing adaptively smoothed images in which all pixel values share the same signal - to - noise ratio _ above the background_.    we apply asmooth to both real observational data ( an x - ray image of clusters of galaxies obtained with the chandra x - ray observatory ) and to a simulated data set.   we find the asmoothed images to be fair representations of the input data in the sense that the residuals are consistent with pure noise, i.e.  they possess poissonian variance and a near - gaussian distribution around a mean of zero, and are spatially uncorrelated.   techniques : image processing  methods : data analysis  methods : statistical
january 2000 completes the first season of intensive, wide - field observations of microlensing and stellar variability in m31 by mega ( `` * m*icrolensing * e*xploration of the * g*alaxy and * a*ndromeda '' ) at the isaac newton 2.5 m telescope, the kpno 4 m, and the 1.3 m and 2.5 m telescopes of mdm observatory. in preliminary analysis  , we detect @xmath050000 variable objects, including some consistent with microlensing events.   we present the level of sensitivity to be reached in our planned three - year program to test for the presence of a significant halo microlensing population in m31, as well as its spatial distribution and mass - function.   we also discuss our application of image subtraction to these wide fields and hst wfpc2 snapshot followup observations to confirm candidates identified from previous years surveys.   we present intermediate results from our smaller - field survey, on the mdm 1.3 m and vatican advanced technology 1.8 m telescope, from 1994 - 1998, wherein we have discovered 8 additional probable microlensing events, over about one - half the time base of the project, in addition to confirming three of our original 6 microlensing candidates from 1995.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we discuss four - jet production at the lhc.   we calculate cross section for both single - parton scattering ( sps ) using the alpgen code as well as for double - parton scattering ( dps ) in leading - order collinear approach.   our results are compared with experimental data obtained recently by the cms collaboration.   we show that the alpgen code relatively well describes distributions in transverse momenta and rapidity of each of the four jets ordered by their transverse momenta ( leading, subleading etc. ).   the sps mechanism does not explain the distributions at large rapidity for the leading jet.   the dps mechanism considerably improves the agreement with the experimental data in this corner of the phase space. in order to enhance the relative dps contribution we propose to impose different cuts.   the relative dps contribution increases when decreasing the lower cut on the jet transverse momenta as well as when a low lower cut on the rapidity distance between the most remote jets is imposed.   we predict very flat distribution in azimuthal angle between the most remote jets with low lower cuts on jets transverse momentum.   we identify phase - space corners where the dps content is enhanced relatively to the sps one.
we solve the generalized relativistic harmonic oscillator in 1 + 1 dimensions, i.e., including a linear pseudoscalar potential and quadratic scalar and vector potentials which have equal or opposite signs.   we consider positive and negative quadratic potentials and discuss in detail their bound - state solutions for fermions and antifermions.   the main features of these bound states are the same as the ones of the generalized three - dimensional relativistic harmonic oscillator bound states.   the solutions found for zero pseudoscalar potential are related to the spin and pseudospin symmetry of the dirac equation in 3 + 1 dimensions.   we show how the charge conjugation and @xmath0 chiral transformations relate the several spectra obtained and find that for massless particles the spin and pseudospin symmetry related problems have the same spectrum, but different spinor solutions.   finally, we establish a relation of the solutions found with single - particle states of nuclei described by relativistic mean - field theories with scalar, vector and isoscalar tensor interactions and discuss the conditions in which one may have both nucleon and antinucleon bound states.
motivated by the recent experimental realization of a candidate to the fulde - ferrell ( ff ) and the larkin - ovchinnikov ( lo ) states in one dimensional ( 1d ) atomic fermi gases, we study the quantum phase transitions in these enigmatic, finite momentum - paired superfluids.   we focus on the ff state and investigate the effects of the induced interaction on the stability of the fflo phase in homogeneous spin - imbalanced quasi-1d fermi gases at zero temperature.   when this is taken into account we find a direct transition from the fully polarized to the fflo state in agreement with exact solutions. also, we consider the effect of a finite lifetime of the quasi - particles states in the normal - superfluid instability. in the limit of long lifetimes,   the lifetime effect is irrelevant and the transition is directly from the fully polarized to the fflo state.   we show, however, that for sufficiently short lifetimes there is a quantum critical point ( qcp ), at a finite value of the mismatch of the fermi wave - vectors of the different quasi - particles, that we fully characterize. in this case   the transition is from the fflo phase to a normal partially polarized state with increasing mismatch.
a summary of some recent results from lattice simulations is presented.   these include first calculations of the strangeness magnetic moment of the nucleon, three new studies of the gluon propagator, flux tube attraction in @xmath0 gauge theory, and the static - quark potential and its gluonic excitations.
the optical expansion parallax of ngc  6543 has been detected and measured using two epochs of hst images separated by a time baseline of only three years.   we have utilized three separate methods of deriving the angular expansion of bright fiducials, the results of which are in excellent agreement.   we combine our angular expansion estimates with spectroscopically obtained expansion velocities to derive a distance to ngc  6543 of 1001@xmath0269 pc.   the deduced kinematic age of the inner bright core of the nebula is 1039@xmath0259 years ; however, the kinematic age of the polar caps that surround the core is larger - perhaps the result of deceleration or earlier mass ejection.   the morphology and expansion patterns of ngc  6543 provide insight into a complex history of axisymmetric, interacting stellar mass ejections.   @scaling0.9 # 1=@scaling 1=1
we calculate the differential cross section for the unpolarized semi - inclusive deeply inelastic scattering ( sidis ) process @xmath0 in leading order ( lo ) of perturbative qcd and up to twist-4 in power corrections and study in particular the azimuthal asymmetry @xmath1.   the final results are expressed in terms of transverse momentum dependent ( tmd ) parton matrix elements of the target nucleon up to twist-4  . we also apply it to @xmath2 and illustrate numerically the nuclear dependence of the azimuthal asymmetry @xmath1 by using a gaussian ansatz for the tmd parton matrix elements.
time correlation functions of a hybrid exotic meson operator, with @xmath0, generated in quenched lattice qcd are subjected to a ( bayesian ) maximum entropy analysis.   five distinct spectral levels are uncovered.   their extrapolation into the physical pion mass region suggests a possible relationship to experimentally known states @xmath1 and @xmath2, and also to a state in the 2gev region carrying the same quantum numbers.
the optical implementation of the recently proposed unambiguous identification of coherent states is presented.   our system works as a programmable discriminator between two, in general non - orthogonal weak coherent states.   the principle of operation lies in the interference of three light beams  two program states and one unknown coherent state which can be equal to whichever of the two program states.   the experiment is based on fiber optics.   its results confirm theoretical predictions and the experimental setup can be straightforwardly extended for higher numbers of program states.
we have developed a nonlinear differential effective dipole approximation ( ndeda ), in an attempt to investigate the effective linear and third - order nonlinear susceptibility of composite media in which graded spherical inclusions with weak nonlinearity are randomly embedded in a linear host medium.   alternatively, based on a first - principles approach, we derived exactly the linear local field inside the graded particles having power - law dielectric gradation profiles. as a result, we obtain also the effective linear dielectric constant and third - order nonlinear susceptibility.   excellent agreement between the two methods is numerically demonstrated. as an application  , we apply the ndeda to investigate the surface plasma resonant effect on the optical absorption, optical nonlinearity enhancement, and figure of merit of metal - dielectric composites.   it is found that the presence of gradation in metal particles yields a broad resonant band in the optical region, and further enhances the figure of merit.    *   pacs number(s ) : * 77.22.ej, 42.65.-k, 42.79.ry, 77.84.lf
we study non - thermal emissions from cool cores in galaxy clusters.   we adopted a recent model, in which cosmic - rays ( crs ) prevail in the cores and stably heat them through cr streaming.   the non - thermal emissions come from the interaction between cr protons and intracluster medium ( icm ).   comparison between the theoretical predictions and radio observations shows that the overall cr spectra must be steep, and most of the crs in the cores are low - energy crs. assuming that the crs are injected through agn activities, we study the nature of the shocks that are responsible for the cr acceleration.   the steep cr spectra are likely to reflect the fact that the shocks travel in hot icm with fairly small much numbers.   we also study the dependence on the cr streaming velocity.   the results indicate that synchrotron emissions from secondary electrons should be observed as radio mini - halos in the cores.   in particular, low - frequency observations ( e.g. _ lofar _ ) are promising. on the other hand,   the steepness of the spectra makes it difficult to detect non - thermal x - ray and gamma - ray emissions from the cores.   the low - energy crs may be heating optical filaments observed in the cores.
we construct quantum field theory in an analogue curved spacetime in bose - einstein condensates based on the bogoliubov - de gennes equations, by exactly relating quantum particles in curved spacetime with bogoliubov quasiparticle excitations in bose - einstein condensates. here  , we derive a simple formula relating the two, which can be used to calculate the particle creation spectrum by solving the time - dependent bogoliubov - de gennes equations. using our formulation,   we numerically investigate particle creation in an analogue expanding universe which can be expressed as bogoliubov quasiparticles in an expanding bose - einstein condensate.   we obtain its spectrum, which follows the thermal maxwell - boltzmann distribution, the temperature of which is experimentally attainable.   our derivation of the analogy is useful for general bose - einstein condensates and not limited to homogeneous ones, and our simulation is the first example of particle creations by solving the bogoliubov - de gennes equation in an inhomogeneous condensate.
we study the effect of non - radial motions on the mass function, the _ velocity dispersion function _ ( hereafter vdf ) and on the shape of clusters of galaxies using the model introduced in del popolo & gambera ( 1998a, b ; 1999 ).   the mass function of clusters, obtained using the quoted model, is compared with the statistical data by bahcall & cen ( 1992a, b ) and girardi et al.   ( 1998 ), while the vdf is compared with the center for astrophysics ( hereafter cfa ) data by zabludoff et al.   ( 1993 ) for local clusters and those of mazure et al.   ( 1996 ) and fadda et al.   ( 1996 ). in both cases the model predictions are in good agreement with the observational data showing once more how non - radial motions can reduce many of the discrepancies between cold dark matter ( hereafter cdm ) model predictions and observational data.   finally we study the effect of non - radial motions on the intrinsic shape of clusters of galaxies showing that non - radial motions produce clusters less elongated with respect to cdm model in agreement with de theije et al.   ( 1995, 1997 ) results.
it is discussed how the dijet azimuthal correlations in dis and real photoproduction at hera probe the unintegrated gluon distribution in the proton.   the correlation function shows a strong dependence on kinematical variables.   we discuss a possible interplay of perturbative and nonperturbative effects.
in this article we consider two spin@xmath0 chains described, respectively, by the thermodynamic limit of the @xmath1 model with the usual two site interaction, and an extension of this model ( without taking the thermodynamics limit ), called @xmath2, were a three site interaction term is presented. to investigate the critical behaviour of such systems we employ tools from quantum information theory.   specifically, we show that the local quantum uncertainty, a quantity introduced in order to quantify the minimum quantum share of the variance of a local measurement, can be used to indicate quantum phase transitions presented by these models at zero temperature. due to the connection of this quantity with the quantum fisher information  , the results presented here may be relevant for quantum metrology and quantum thermodynamics.
some anisotropy in both mechanical and thermodynamical properties of bismuth is expected. a combination of density functional theory total energy calculations and density functional perturbation theory in the local density approximation is used to compute the elastic constants at 0 k using a finite strain approach and the thermal expansion tensor in the quasiharmonic approximation.   the overall agreement with experiment is good.   furthermore, the anisotropy in the thermal expansion is found to arise from the anisotropy in both the directional compressibilities and the directional grneisen functions.
we present analyses of the spatial and spectral evolution of hard x - ray emission observed by _ rhessi _ during the impulsive phase of an m1.7 flare on 2003 november 13. in general,   as expected, the loop top ( lt ) source dominates at low energies while the footpoint ( fp ) sources dominate the high energy emission. at intermediate energies,   both the lt and fps may be seen, but during certain intervals emission from the legs of the loop dominates, in contrast to the commonly observed lt and fp emission.   the hard x - ray emission tends to rise above the fps and eventually merge into a single lt source.   this evolution starts first at low energies and proceeds to higher energies.   the spectrum of the resultant lt source becomes more and more dominated by a thermal component with an increasing emission measure as the flare proceeds.   the soft and hard x - rays show a neupert - type behavior. with a non - thermal bremsstrahlung model the brightness profile along the loop   is used to determine the density profile and its evolution, which reveals a gradual increase of the gas density in the loop.   these results are evidence for chromospheric evaporation and are consistent with the qualitative features of hydrodynamic simulations of this phenomenon. however, some observed source morphology and its evolution can not be accounted for by previous simulations  . therefore simulations with more realistic physical conditions are required to explain the results and the particle acceleration and plasma heating processes.
we discuss the host galaxy metallicity distribution of all long gamma - ray bursts ( grbs ) whose redshifts are known to be @xmath0, including newly obtained spectroscopic datasets of the host galaxies of grb 060614, 090417b, and 130427a.   we compare the metallicity distribution of the low - redshift sample to the model predictions, and constrain the relation between metallicity and grb occurrence.   we take account of spatial variation of metallicities among star forming regions within a galaxy.   we found that the models, in which only low - metallicity stars produce grbs with a sharp cutoff of grb production efficiency around 12+log(o / h ) @xmath1 8.3, can well reproduce the observed distribution, while the models with no metallicity dependence are not consistent with the observations.   we also discuss possible sampling biases we may suffer by collecting long grbs whose redshifts are known, presenting the photometric observations of the host galaxy of grb 111225a at @xmath2 whose redshift has been undetermined until @xmath1 2.3 years after the burst.
we present a comprehensive computational study on the properties of face - centered cubic and hexagonal chalcogenide ge@xmath0sb@xmath0te@xmath1.   we calculate the electronic structure using density functional theory ( dft ) ; the obtained density of states ( dos ) compares favorably with experiments, also looking suitable for transport analysis.   optical constants including refraction index and absorption coefficient capture major experimental features, aside from an energy shift owed to an underestimate of the band gap that is typical of dft calculations.   we also compute the phonon dos for the hexagonal phase, obtaining a speed of sound and thermal conductivity in good agreement with the experimental lattice contribution.   the calculated heat capacity reaches  @xmath2  j/(m@xmath3  k ) at high temperature, in agreement with experimental data, and provides insight into the low - temperature range ( @xmath4 k ), where data are unavailable.
calculations of the number of equivalence classes of sudoku boards has to this point been done only with the aid of a computer, in part because of the unnecessarily large symmetry group used to form the classes. in particular, the relationship between relabeling symmetries and positional symmetries such as row / column swaps is complicated. in this paper   we focus first on the smaller shidoku case and show first by computation and then by using connectivity properties of simple graphs that the usual symmetry group can in fact be reduced to various minimal subgroups that induce the same action.   this is the first step in finding a similar reduction in the larger sudoku case and for other variants of sudoku.
i propose an archtitecture for the realization of dissipative quantum many - body spin models.   the dissipative processes are mediated by interactions with auxiliary particles and lead to a widely tunable class of correlated quantum jump operators.   these findings enable the investigation of purely dissipative spin models, where coherent dynamics is entirely absent.   i provide a detailed review of a recently introduced variational method to analyze such dissipative quantum many - body systems, and i discuss a specific example in terms of a purely dissipative heisenberg model, for which i find an additional disordered phase that is not present in the corresponding ground state phase diagram.
patience sorting is a combinatorial algorithm that can be viewed as an iterated, non - recursive form of the schensted insertion algorithm. in recent work   the authors extended patience sorting to a full bijection between the symmetric group and certain pairs of combinatorial objects ( called _ pile configurations _ ) that are most naturally defined in terms of generalized permutation patterns and barred pattern avoidance.   this extended patience sorting algorithm is very similar to the robinson - schensted - knuth ( or rsk ) correspondence, which is itself built from repeated application of the schensted insertion algorithm.    in this work   we introduce a geometric form for the extended patience sorting algorithm that is in some sense a natural dual algorithm to g. viennot s celebrated geometric rsk algorithm. unlike geometric rsk, though, the lattice paths coming from patience sorting are allowed to intersect.   we thus also give a characterization for the intersections of these lattice paths in terms of the pile configurations associated with a given permutation under the extended patience sorting algorithm.
in this work we investigate an influence of decoherence effects on quantum states generated as a result of the cross - kerr nonlinear interaction between two modes. for markovian losses ( both photon loss and dephasing ),   a region of parameters when losses still do not lead to destruction of non - classicality is identified.   we emphasize the difference in impact of losses in the process of state generation as opposed to those occurring in propagation channel.   we show moreover, that correlated losses in modern realizations of schemes of large cross - kerr nonlinearity might lead to enhancement of non - classicality.
we consider a recently  proposed alternative explanation of the cv period gap in terms of a revised mass  radius relation for the lower main sequence. we show that no such thermal  equilibrium relation is likely to produce a true gap.   using population synthesis techniques we calculate a model population that obeys the claimed equilibrium mass  radius relation.   a theoretical period histogram obtained from this population shows two prominent period spikes rather than a gap.   we consider also recent arguments suggesting that the period gap itself may not be real.   we argue that, far from demonstrating a weakness of the interrupted  braking picture, the fact that most cv subtypes prefer one side of the gap or the other is actually an expected consequence of it.   2im_2,i    # 1= # 1#2=.45 =.45 # 1#2#3#4#5#6#7    to#2   ''' ''    accretion, accretion discs  novae, cataclysmic variables  binaries : close  stars : evolution  star : low  mass.
we use simulated maps to investigate the ability of high resolution, low noise surveys of the cmb to create catalogues of clusters of galaxies by detecting the characteristic signature imprinted by the sunyaev zeldovich effect.   we compute the completeness of the catalogues in our simulations for several survey strategies, and evaluate the relative merit of some fourier and wavelet based filtering techniques.   ,   cosmology, large - scale structures, theory 98.65.dx, 98.80.es, 98.70.vc
collisions of antiprotons with he-, ne-, ni - like, bare, and neutral uranium are studied theoretically for scattering angles close to 180@xmath0 and antiproton energies with the interval 100 ev  10 kev.   we investigate the coulomb glory effect which is caused by a screening of the coulomb potential of the nucleus and results in a prominent maximum of the differential cross section in the backward direction at some energies of the incident particle.   we found that for larger numbers of electrons in the ion the effect becomes more pronounced and shifts to higher energies of the antiproton. on the other hand,   a maximum of the differential cross section in the backward direction can also be found in the scattering of antiprotons on a bare uranium nucleus.   the latter case can be regarded as a manifestation of the screening property of the vacuum - polarization potential in non - relativistic collisions of heavy particles.
we introduce an adiabatic long - range quantum communication proposal based on a quantum dot array. by adiabatically varying the external gate voltage applied on the system,   the quantum information encoded in the electron can be transported from one end dot to another.   we numerically solve the schrdinger equation for a system with a given number of quantum dots.   it is shown that this scheme is a simple and efficient protocol to coherently manipulate the population transfer under suitable gate pulses.   the dependence of the energy gap and the transfer time on system parameters is analyzed and shown numerically.   we also investigate the adiabatic passage in a more realistic system in the presence of inevitable fabrication imperfections.   this method provides guidance for future realizations of adiabatic quantum state transfer in experiments.   adiabatic passage, tight - binding model, quantum state transfer    pacs : 03.65.-w, 03.67.hk, 73.23.hk
we consider the higgs - dilaton(radion ) system using the trace of the energy - momentum tensor ( @xmath0 ) with the full standard model ( sm ) gauge symmetry @xmath1, and find out that the resulting phenomenology for the higgs - dilaton(radion ) system is distinctly different from the earlier studies based on the @xmath0 with the unbroken subgroup @xmath2 of @xmath3.   after electroweak symmetry breaking ( ewsb ), the sm higgs boson and dilaton(radion ) will mix with each other, and there appear two higgs - like scalar bosons and the higgs - dilaton mixing changes the scalar phenomenology in interesting ways.   the signal strengths for the @xmath4-initiated channels could be modified significantly compared with the sm predictions due to the qcd scale anomaly and the higgs - dilaton(radion ) mixing, whereas anomaly contributions are almost negligible for other channels.   we also discuss the self - couplings and the signal strengths of the @xmath5 gev scalar boson in various channels and possible constraints from the extra light / heavy scalar boson.   the higgs - dilaton(radion ) system considered in this work has a number of distinctive features that could be tested by the upcoming lhc running and at the ilc.
robust control theory has been successfully applied to numerous real - world problems using a small set of devices called _   controllers_. however, the real systems represented by networks contain unreliable components and modern robust control engineering has not addressed the problem of structural changes on a large network. here  , we introduce the concept of structurally robust control of complex networks and provide a concrete example using an algorithmic framework that is widely applied in engineering.   the developed analytical tools, computer simulations and real network analyses lead herein to the discovery that robust control can be achieved in scale - free networks with exactly the same order of controllers required in a standard non - robust configuration by adjusting only the minimum degree.   the presented methodology also addresses the probabilistic failure of links in real systems, such as neural synaptic unreliability in _ c. elegans _, and suggests a new direction to pursue in studies of complex networks in which control theory has a role.
molecular dynamics ( md ) simulations are used to investigate @xmath0h nuclear magnetic resonance ( nmr ) relaxation and diffusion of bulk @xmath1-c@xmath2h@xmath3 to @xmath1-c@xmath4h@xmath5 hydrocarbons and bulk water.   the md simulations of the @xmath0h nmr relaxation times @xmath6 in the fast motion regime where @xmath7 agree with measured ( de - oxygenated ) @xmath8 data at ambient conditions, without any adjustable parameters in the interpretation of the simulation data. likewise, the translational diffusion @xmath9 coefficients calculated using simulation configurations are well - correlated with measured diffusion data at ambient conditions.   the agreement between the predicted and experimentally measured nmr relaxation times and diffusion coefficient also validate the forcefields used in the simulation.   the molecular simulations naturally separate intramolecular from intermolecular dipole - dipole interactions helping bring new insight into the two nmr relaxation mechanisms as a function of molecular chain - length ( i.e. carbon number ).   comparison of the md simulation results of the two relaxation mechanisms with traditional hard - sphere models used in interpreting nmr data reveals important limitations in the latter. with increasing chain length  , there is substantial deviation in the molecular size inferred on the basis of the radius of gyration from simulation and the fitted hard - sphere radii required to rationalize the relaxation times.   this deviation is characteristic of the local nature of the nmr measurement, one that is well - captured by molecular simulations.
we calculate the finite vacuum energy density of the scalar and electromagnetic fields inside a casimir apparatus made up of two conducting parallel plates in a general weak gravitational field.   the metric of the weak gravitational field has a small deviation from flat spacetime inside the apparatus and we find it by expanding the metric in terms of small parameters of the weak background. we show that the found metric can be transformed via a gauge transformation to the fermi metric.   we solve the klein - gordon equation exactly and find mode frequencies in fermi spacetime.   using the fact that the electromagnetic field can be represented by two scalar fields in the fermi spacetime, we find general formulas for the energy density and mode frequencies of the electromagnetic field.   some well - known weak backgrounds are examined and consistency of the results with the literature is shown.
ap / bp stars are magnetic chemically peculiar early a and late b type stars of the main sequence.   they exhibit peculiar surface abundance anomalies that are thought to be the result of gravitational settling and radiative levitation.   the physics of diffusion in these stars are reviewed briefly and some model predictions are discussed.   while models reproduce some observations reasonably well, more work is needed before the behavior of diffusing elements in a complex magnetic field is fully understood.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we show that a layered superconductor, described by a two - component order parameter, has a gapped state above the ground state, topologically protected from decay, containing flow and counter flow in the absence of an applied magnetic field.   this state is made of skyrmions, breaks time reversal symmetry and produces a weak local magnetic field below the present threshold of detection by @xmath0sr and nmr / nqr.   we estimate the density of carriers that condense into the pseudogap.
we study a stochastically - driven standard map.   the addition of a noise term destroys the invariant manifolds that organize the phase space which allows for more widespread transport than in the noiseless case. using appropriately defined hitting times to quantify the dynamics, we identify two qualitatively different classes of transport : linear and nonlinear.   linear transport is primarily driven by the stochasticity in the system, while nonlinear transport results from a combination of the nonlinear dynamics and stochasticity and provides a significant speed - up in transport.
we investigate vortex shedding from a moving penetrable obstacle in a highly oblate bose - einstein condensate.   the penetrable obstacle is formed by a repulsive gaussian laser beam that has the potential barrier height lower than the chemical potential of the condensate.   the moving obstacle periodically generates vortex dipoles and the vortex shedding frequency @xmath0 linearly increases with the obstacle velocity @xmath1 as @xmath2, where @xmath3 is a critical velocity.   based on periodic shedding behavior, we demonstrate deterministic generation of a single vortex dipole by applying a short linear sweep of a laser beam.   this method will allow further controlled vortex experiments such as dipole - dipole collisions.
we derive general expressions at the one - loop level for the coefficients of the covariant structure of the neutrino self - energy in the presence of a constant magnetic field.   the neutrino energy spectrum and index of refraction are obtained for neutral and charged media in the strong - field limit ( @xmath0 ) using the lowest landau level approximation.   the results found within the lowest landau level approximation are numerically validated, summing in all landau levels, for strong @xmath1 and weakly - strong @xmath2 fields.   the neutrino energy in leading order of the fermi coupling constant is expressed as the sum of three terms : a kinetic - energy term, a term of interaction between the magnetic field and an induced neutrino magnetic moment, and a rest - energy term.   the leading radiative correction to the kinetic - energy term depends linearly on the magnetic field strength and is independent of the chemical potential.   the other two terms are only present in a charged medium. for strong and weakly - strong fields  , it is found that the field - dependent correction to the neutrino energy in a neutral medium is much larger than the thermal one.   possible applications to cosmology and astrophysics are considered.    0.0 in
we review the main proposals of particle physics for the composition of the cold dark matter in the universe.   strong axion contribution to cold dark matter is not favored if the peccei - quinn field emerges with non - zero value at the end of inflation and the inflationary scale is superheavy since, under these circumstances, it leads to unacceptably large isocurvature perturbations.   the lightest neutralino is the most popular candidate constituent of cold dark matter.   its relic abundance in the constrained minimal supersymmetric standard model can be reduced to acceptable values by pole annihilation of neutralinos or neutralino - stau coannihilation.   axinos can also contribute to cold dark matter provided that the reheat temperature is adequately low.   gravitinos can constitute the cold dark matter only in limited regions of the parameter space.   we present a supersymmetric grand unified model leading to violation of yukawa unification and, thus, allowing an acceptable @xmath0-quark mass within the constrained minimal supersymmetric standard model with @xmath1.   the model possesses a wide range of parameters consistent with the data on the cold dark matter abundance as well as other phenomenological constraints.   also, it leads to a new version of shifted hybrid inflation.
current measurements of the hubble constant @xmath0 on scale less than @xmath1 mpc appear to be controversial, while the observations made at high redshift seem to provide a relatively low value. on the other hand,   the hubble expansion is driven by the matter content of the universe. the dynamical analysis on scale of a few   @xmath2 mpc indicates that the matter density @xmath3 is only @xmath4@xmath5, which is significantly smaller than @xmath6 predicted in the standard inflation model.   this might support the tendency of a decreasing hubble constant towards distance. in this paper, we discuss the influence of a possible variant hubble constant on two fundamental relations in astronomy : the magnitude - redshift ( @xmath7@xmath8 ) and the number - magnitude relations. using a distant type ia supernova at @xmath9  , we show that the deceleration parameter @xmath10 or @xmath3 can not be determined from the @xmath7@xmath8 relation at moderate / high redshift unless the variation of the hubble constant is _ a priori _ measured.   it is further demonstrated that the number density of distant sources would be underestimated when their local calibration is employed, which may partially account for the number excess of the faint blue galaxies observed at moderate / high redshift.
the low - mass condensations ( lmcs ) have been observed within the molecular cloud cores. in this research  , we investigate the effect of isobaric thermal instability ( ti ) applied for forming these lmcs. for this purpose,   at first we investigate the occurrence of ti in the molecular clouds.   then, for studying the significance of linear isobaric ti, we use a contracting axisymmetric cylindrical core with axial magnetic field.   consideration to cooling and heating mechanisms in the molecular clouds shows that including the heating due to ambipolar diffusion can lead to the occurrence of ti in a time - scale smaller than dynamical time - scale.   application of linear perturbation analysis shows that isobaric ti can take place in outer region of the molecular cloud cores.   furthermore, the results show that perturbations with wavelengths greater than few astronomical units are protected from destabilization property of thermal conduction, so they can grow to form lmcs.   thus, the results show that the mechanism of ti can be used to explain the formation of lmcs as the progenitors of collapsing proto - stellar entities, brown dwarfs, or proto - planets.
almost all groups involved in linear collider detector studies have their own simulation software framework.   using a common persistency scheme would allow to easily share results and compare reconstruction algorithms.   we present such a persistency framework, called lcio ( linear collider i / o ). the framework has to fulfill the requirements of the different groups today and be flexible enough to be adapted to future needs. to that end   we define an ` abstract object persistency layer'that will be used by the applications. a first implementation, based on a sequential file format ( sio ) is completely separated from the interface, thus allowing to support additional formats if necessary.   the interface is defined with the aid ( abstract interface definition ) tool from freehep.org that allows creation of java and c++ code synchronously. in order to make use of legacy software a fortran interface   is also provided.   we present the design and implementation of lcio.
we investigate the dependence of the total - infrared ( tir ) to uv luminosity ratio method for calculating the uv dust attenuation @xmath0 from the age of the underlying stellar populations by using a library of spectral energy distributions for galaxies with different star formation histories.   our analysis confirms that the @xmath1 vs. @xmath0 relation varies significantly with the age of the underlying stellar population : i.e. for the same @xmath1 ratio, systems with low specific star formation rate ( ssfr ) suffer a lower uv attenuation than starbursts. using a sample of nearby field and cluster spiral galaxies   we show that the use of a standard ( i.e. age independent ) @xmath1 vs. @xmath0 relation leads to a systematic overestimate up to 2 magnitudes of the amount of uv dust attenuation suffered by objects with low ssfr and in particular hi - deficient star forming cluster galaxies.   this result points out that the age independent @xmath1 vs. @xmath0 relation can not be used to study the uv properties of large samples of galaxies including low star - forming systems and passive spirals.   therefore we give some simple empirical relations from which the uv attenuation can be estimated taking into account its dependence on the age of the stellar populations, providing a less biased view of uv properties of galaxies.       galaxies : general  galaxies : fundamental parameters  galaxies : evolution  ultraviolet : galaxies
we investigate the physics of coherent quantum phase slips in two distinct circuits containing small josephson junctions : ( i ) a single junction embedded in an inductive environment and ( ii ) a long chain of junctions.   starting from the standard josephson hamiltonian, the single junction circuit can be analyzed using quasi - classical methods ; we formulate the conditions under which the resulting quasi - charge dynamics is exactly dual to the usual phase dynamics associated with josephson tunneling. for the chain we use the fact that its collective behavior can be characterized by one variable : the number @xmath0 of quantum phase slips present on it.   we conclude that the dynamics of the conjugate quasi - charge is again exactly dual to the standard phase dynamics of a single josephson junction. in both cases   we elucidate the role of the inductance, essential to obtain exact duality.   these conclusions have profound consequences for the behavior of single junctions and chains under microwave irradiation.   since both systems are governed by a model exactly dual to the standard resistively and capacitively shunted junction model, we expect the appearance of current - shapiro steps.   we numerically calculate the corresponding current - voltage characteristics in a wide range of parameters.   our results are of interest in view of a metrological current standard.
it is found that cp symmetry may be explicitly broken in the higgs sector of a supersymmetric @xmath0 model with two extra neutral gauge bosons at the one - loop level.   the phenomenology of the model, the higgs sector in particular, is studied for a reasonable parameter space of the model, in the presence of explicit cp violation at the one - loop level.   at least one of the neutral higgs bosons of the model might be produced via the @xmath1 fusion process at the large hadron collider.   +   + keywords : higgs physics, supersymmetric standard model
_ standard _ models for the chemical evolution of the galaxy are reviewed with particular emphasis on the history of the abundance gradients in the disk. the effects on the disk structure and metallicity of gas accretion are discussed, showing that a significant fraction of the current disk mass has been accreted in the last gyrs and that the chemical abundances of the infalling gas can be non primordial but should not exceed @xmath00.3 z@xmath1.   the distributions with time and with galactocentric distance of chemical elements are discussed, comparing the observational data with the corresponding theoretical predictions by _ standard _ models, which reproduce very well the ism abundances at various epochs, but not equally well all the features derived from observations of old stellar objects.
studying the environments of 0.4@xmath0z@xmath01.2 uv - selected galaxies, as examples of extreme star - forming galaxies ( with star formation rates in the range of 3@xmath130m@xmath2 yr@xmath3 ), we explore the relationship between high rates of star - formation, host halo mass and pair fractions.   we study the large - scale and small - scale environments of local ultraviolet luminous galaxies ( uvlgs ) by measuring angular correlation functions.   we cross - correlate these systems with other galaxy samples : a volume - limited sample ( all ), a blue luminous galaxy sample ( blg ) and a luminous red galaxy sample ( lrg ).   we determine the uvlg comoving correlation length to be r@xmath4 h@xmath3mpc at @xmath5z@xmath61.0, which is unable to constrain the halo mass for this sample.   however, we find that uvlgs form close ( separation @xmath0 30 kpc ) pairs with the all sample, but do not frequently form pairs with lrgs  . a rare subset of uvlgs, those with the highest fuv surface brightnesses, are believed to be local analogs of high redshift lyman break galaxies ( lbgs ) and are called lyman break analogs ( lbas ).   lbgs and lbas share similar characteristics ( i.e., color, size, surface brightness, specific star formation rates, metallicities, and dust content ).   recent _ hst _   images of z@xmath70.2 lbas show disturbed morphologies, signs of mergers and interactions.   uvlgs may be influenced by interactions with other galaxies and we discuss this result in terms of other high star - forming, merging systems.
the accuracy of monte carlo glauber model descriptions of minimum - bias multiplicity frequency distributions is evaluated using data from the relativistic heavy ion collider ( rhic ) within the context of a sensitive, power - law representation introduced previously by trainor and prindle ( tp ).   uncertainties in the glauber model input and in the mid - rapidity multiplicity frequency distribution data are reviewed and estimated using the tp centrality methodology.   the resulting errors in model - dependent geometrical quantities used to characterize heavy ion collisions ( _ i.e. _ impact parameter, number of nucleon participants @xmath0, number of binary interactions @xmath1, and average number of binary collisions per incident participant nucleon @xmath2 ) are presented for minimum - bias au - au collisions at @xmath3 = 20, 62, 130 and 200  gev and cu - cu collisions at @xmath3 = 62 and 200  gev.   considerable improvement in the accuracy of collision geometry quantities is obtained compared to previous monte carlo glauber model studies, confirming the tp conclusions.   the present analysis provides a comprehensive list of the sources of uncertainty and the resulting errors in the above geometrical collision quantities as functions of centrality.   the capability of energy deposition data from trigger detectors to enable further improvements in the accuracy of collision geometry quantities is also discussed.
we present mid - infrared ( mir ) @xmath0 m spectroscopy of the nuclear regions of the interacting galaxy arp  299 ( ic  694+ngc  3690 ) obtained with canaricam ( cc ) on the 10.4 m gran telescopio canarias ( gtc ).   the high angular resolution ( @xmath1 ) of the data allows us to probe nuclear physical scales between 60 and 120pc, which is a factor of 10 improvement over previous mir spectroscopic observations of this system.   the gtc / cc spectroscopy displays evidence of deeply embedded active galactic nucleus ( agn ) activity in both nuclei.   the gtc / cc nuclear spectrum of ngc  3690/arp  299-b1 can be explained as emission from agn - heated dust in a clumpy torus with both a high covering factor and high extinction along the line of sight.   the estimated bolometric luminosity of the agn in ngc  3690 is @xmath2.   the nuclear gtc / cc spectrum of ic  694/arp  299-a shows @xmath3 m polycyclic aromatic hydrocarbon ( pah ) emission stemming from a deeply embedded ( @xmath4mag ) region of less than 120pc in size.   there is also a continuum - emitting dust component.   if associated with the putative agn in ic  694, we estimate that it would be approximately 5 times less luminous than the agn in ngc  3690.   the presence of dual agn activity makes arp  299 a good example to study such phenomenon in the early coalescence phase of interacting galaxies.
the self - energy of the @xmath0 meson in nuclear matter is calculated in a self - consistent microscopic approach, using a @xmath1 interaction obtained from the lowest - order meson - baryon chiral lagrangian. the effective @xmath1 interaction in the medium   is derived by solving the coupled - channel bethe - salpeter equation including pauli blocking on the nucleons, mean - field binding potentials for the baryons and the self - energy of the @xmath2 and @xmath3 mesons.   the incorporation of the self - consistent @xmath4 self - energy in the description, in addition to the pauli blocking effects, yields a weaker attractive in - medium @xmath5 interaction and a @xmath6 which dissolves faster with increasing matter density, as a result of the @xmath7 spectral function being spread out over a wide range of energies.   these effects are further magnified when the intermediate pions are dressed.    0.5 cm    _ pacs : _   12.38.lg, 13.75.jz, 14.20.gk, 14.20.jn, 14.40.aq, 21.65.+f, 25.80.nv    _ keywords : _   @xmath1 interaction, chiral lagrangian, @xmath6 in nuclear matter, effective kaon mass, kaonic atoms.
the location and asymptotic behaviour for large @xmath0 of the zeros of exceptional jacobi and laguerre polynomials are discussed.   the zeros of exceptional polynomials fall into two classes : the _ regular zeros _, which lie in the interval of orthogonality and the _ exceptional zeros _, which lie outside that interval.   we show that the regular zeros have two interlacing properties : one is the natural interlacing between consecutive polynomials as a consequence of their sturm - liouville character, while the other one shows interlacing between the zeros of exceptional and classical polynomials.   a generalization of the classical heine - mehler formula is provided for the exceptional polynomials, which allows to derive the asymptotic behaviour of their regular zeros.   we also describe the location and the asymptotic behaviour of the _ exceptional zeros _, which converge for large @xmath0 to fixed values.
multiple - antenna  based " transmitter ( tx ) cooperation has been established as a promising tool towards avoiding, aligning, or shaping the interference resulting from aggressive spectral reuse. the price paid in the form of feedback and exchanging channel state information ( csi ) between cooperating devices in most existing methods   is often underestimated however. in reality, feedback and information overhead threatens the practicality and scalability of tx cooperation approaches in dense networks.   hereby we addresses a  who needs to know what? "   problem, when it comes to csi at cooperating transmitters.   a comprehensive answer to this question remains beyond our reach and the scope of this paper.   nevertheless, recent results in this area suggest that csi overhead can be contained for even large networks provided the allocation of feedback to txs is made non - uniform and to properly depend on the network s topology.   this paper provides a few hints toward solving the problem.
we use first - principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half - metal phase in lamno@xmath0.   we identify the q2 jahn - teller mode as the primary mechanism that drives the transition, indicating that this mode can be used to tune the lattice, charge, and spin coupling. applying @xmath1 6 gpa of uniaxial pressure along the  direction   activates the transition to a half - metallic @xmath2 state.   the half - metallicity opens the possibility of producing colossal magnetoresistance in the stoichiometric lamno@xmath0 compound at significantly lower pressure compared to recently observed investigations using hydrostatic pressure.   pacs numbers : :    71.30.+h, 31.15.a-, 81.40.vw, 71.70.ej, 75.47.gk
traffic jam has been a daily problem for people in jakarta which is one of the busiest city in indonesia up until now.   even though the official government has tried to reduce the impact of traffic issues by developing a new public transportation which takes up a lot of resources and time, it failed to diminish the problem. the actual concern to   this problem actually lies in how people move between places in jakarta where they always using their own vehicle like cars, and motorcycles that fill most of the street in jakarta. among much other public transportations that roams the street of jakarta  , buses is believed to be an efficient transportation that can move many people at once.   however, the location of the bus stop is now have moved to the middle of the main road, and it s too far for the nearby residence to access to it.   this paper proposes an optimal location of optimal bus stops in west jakarta that is experimentally proven to have a maximal distance of 350 m. the optimal location is estimated by means of mean shift clustering method while the optimal routes are calculated using ant colony algorithm.   the bus stops locations rate of error is 0.07% with overall route area of 32 km. based on our experiments,   we believe our proposed bus stop plan can be an interesting alternative to reduce traffic congestion in west jakarta.
the opening of a gap in single - layer graphene is often ascribed to the breaking of the equivalence between the two carbon sublattices.   we show by angle - resolved photoemission spectroscopy that ir- and na - modified graphene grown on the ir(111 ) surface presents a very large unconventional gap that can be described in terms of a phenomenological `` massless '' dirac model.   we discuss the consequences and differences of this model in comparison of the standard massive gap model, and we investigate the conditions under which such anomalous gap can arise from a spontaneous symmetry breaking.   keywords : graphene, bandgap, dirac cone, angle - resolved - photoemission
extended high - energy(@xmath0 mev ) gamma - ray emission that lasts much longer than the prompt sub - mev emission has been detected from quite a few gamma - ray bursts ( grbs ) by fermi large area telescope ( lat ) recently.   a plausible scenario is that this emission is the afterglow synchrotron emission produced by electrons accelerated in the forward shocks. in this scenario  , the electrons that produce synchrotron high - energy emission also undergo inverse - compton ( ic ) loss and the ic scattering with the synchrotron photons should be in the klein - nishina regime. here   we study effects of the klein - nishina scattering on the high - energy synchrotron afterglow emission.   we find that, at early times the klein - nishina suppression effect on those electrons that produce the high - energy emission is usually strong and therefore their inverse - compton loss is small with a compton parameter @xmath1 for a wide range of parameter space.   this leads to a relatively bright synchrotron afterglow at high energies that can be detected by fermi lat.   as the klein - nishina suppression effect weakens with time, the inverse - compton loss increases and could dominate over the synchrotron loss in some parameter space.   this will lead to a faster temporal decay of the high - energy synchrotron emission than what is predicted by the standard synchrotron model, which may explain the observed rapid decay of the early high - energy gamma - ray emission in grb090510 and grb090902b.
spin - polarized symmetric nuclear matter is studied within the dirac - brueckner - hartree - fock approach.   we pay particular attention to the difference between the one - body potentials of upward and downward polarized nucleons.   this is formally analogous to the  lane potential " for isospin - asymmetric nuclear matter.   we point out the necessity for additional information on this fundamentally important quantity and suggest ways to constrain it.
we consider the chalker - coddington network model for the integer quantum hall effect, and examine the possibility of solving it exactly. in the supersymmetric path   integral framework, we introduce a truncation procedure, leading to a series of well - defined two - dimensional loop models, with two loop flavours. in the phase diagram of the first - order truncated model, we identify four integrable branches related to the dilute birman - wenzl - murakami braid - monoid algebra, and parameterised by the loop fugacity @xmath0. in the continuum limit,   two of these branches ( 1,2 ) are described by a pair of decoupled copies of a coulomb - gas theory, whereas the other two branches ( 3,4 ) couple the two loop flavours, and relate to an @xmath1 wess - zumino - witten ( wzw ) coset model for the particular values @xmath2 $ ] where @xmath3 is a positive integer.   the truncated chalker - coddington model is the @xmath4 point of branch 4. by numerical diagonalisation  , we find that its universality class is neither an analytic continuation of the wzw coset, nor the universality class of the original chalker - coddington model.   it constitutes rather an integrable, critical approximation to the latter.
we compare the first results on searches for supersymmetry with the large hadron collider ( lhc ) to the current and near - term performance of experiments sensitive to neutralino dark matter.   we limit our study to the particular slices of parameter space of the constrained minimal supersymmetric extension to the standard model where cms and atlas exclusion limits have been presented so far.   we show where, on that parameter space, the lightest neutralino possesses a thermal relic abundance matching the value inferred by cosmological observations.   we then calculate rates for, and estimate the performance of, experiments sensitive to direct and indirect signals from neutralino dark matter.   we argue that this is a unique point in time, where the quest for supersymmetry  at least in one of its practical and simple incarnations  is undergoing a close scrutiny from the lhc and from dark matter searches that is both synergistic and complementary.   should the time of discovery finally unravel, the current performances of the collider program and of direct and indirect dark matter searches are at a conjuncture offering unique opportunities for a breakthrough on the nature of physics beyond the standard model.
recently, advanced laser interferometer gravitational - wave observatory ( aligo ) detected gravitational wave ( gw ) transients from mergers of binary black holes ( bhs ). the system may also produce a wide - angle, relativistic outflow if the claimed short grb detected by gbm is in real association with gw 150914.   it was suggested that mergers of double neutron stars ( or neutron star - black hole binaries ), another promising source of gw transients, also produce fast, wide - angle outflows. in this paper  , we calculate the high - energy gamma - ray emission arising from the blast waves driven by these wide - angle outflows.   we find that tev emission arising from the inverse - compton process in the relativistic outflow resulted from mergers of binary bhs similar to those in gw 150914 could be detectable by ground - based iact telescopes such as cherenkov telescope array ( cta ) if the sources occur in a dense medium with density @xmath0. for neutron star - neutron star ( ns - ns ) and ns - bh mergers,   tev emission from the wide - angle, mildly - relativistic outflow could be detected as well if they occur in a dense medium with @xmath1.   thus tev afterglow emission would be a useful probe of the environment of the gw transients, which could shed light on the evolution channels of the progenitors of gw transients.
in this paper we study the influence of hard supersymmetry breaking terms in a @xmath0, @xmath1 supersymmetric model, in @xmath2 spacetime topology. it is found that for some interaction terms and for certain values of the couplings, supersymmetry is unbroken for small lengths of the compact radius, and breaks dynamically as the radius increases.   also for another class of interaction terms, when the radius is large supersymmetry is unbroken and breaks dynamically as the radius decreases.   it is pointed out that the two phenomena have similarities with the theory of metastable vacua at finite temperature and with the inverse symmetry breaking of continuous symmetries at finite temperature ( where the role of the temperature is played by the compact dimension s radius ).
the quenching of oscillations in interacting systems leads to several unwanted situations, which necessitate a suitable remedy to overcome the quenching. in this connection  , this work addresses a mechanism that can resurrect oscillations in a typical situation. through both numerical and analytical studies,   we show the candidate which is capable of resurrecting oscillations is nothing but the feedback, the one which is profoundly used in dynamical control and in bio - therapies. even in the case of a rather general system, we demonstrate analytically the applicability of the technique over one of the oscillation quenched states called amplitude death state.   we also discuss some of the features of this mechanism such as adaptability of the technique with the feedback of only a few of the oscillators.
the classical einstein gravity description of black hole production in transplanckian collisions in tev - scale gravity is tested for self - consistency.   in addition to the  curvature must be small " test, which was shown to be violated in , it is proposed to estimate quantum fluctuations in the aichelburg - sexl shock waves corresponding to the colliding particles. using linearized quantum gravity, it is found that the occupation numbers of gravitons with characteristic frequency are too small to resolve the classical width of the shocks.   this raises further doubts in the classical gravity picture of black hole creation and the geometric cross section estimate based on it.   hep - ph/0405104 + itfa-2004 - 19    large extra dimensions, tev - scale gravity, transplanckian collisions 04.70.-s, 04.50.+h, 11.10kk
we address the problem of estimating a sparse low - rank matrix from its noisy observation.   we propose an objective function consisting of a data - fidelity term and two parameterized non - convex penalty functions.   further, we show how to set the parameters of the non - convex penalty functions, in order to ensure that the objective function is strictly convex. the proposed objective function better estimates sparse low - rank matrices than a convex method which utilizes the sum of the nuclear norm and the @xmath0 norm.   we derive an algorithm ( as an instance of admm ) to solve the proposed problem, and guarantee its convergence provided the scalar augmented lagrangian parameter is set appropriately.   we demonstrate the proposed method for denoising an audio signal and an adjacency matrix representing protein interactions in the ` escherichia coli'bacteria.   low - rank matrix, sparse matrix, speech denoising, nonconvex regularization, convex optimization
the nuclear incompressibility @xmath0 is deduced from measurements of the isoscalar giant monopole resonance ( isgmr ) in medium - heavy nuclei, and the resulting value turns out to be model dependent.   since the considered nuclei have neutron excess, it has been suggested that the model dependence is due to the different behaviour of the symmetry energy in different models. to clarify this issue  , we make a systematic and careful analysis based on new skyrme forces which span a wide range of values for @xmath0, for the value of the symmetry energy at saturation and for its density dependence. by calculating, in a fully self - consistent fashion, the isgmr centroid energy in @xmath1pb   we reach, for the first time within the non - relativistic framework, three important conclusions : ( i ) the monopole energy, and consequently the deduced value of @xmath0, depend on a well defined parameter related to the shape of the symmetry energy curve and called @xmath2 ; ( ii ) skyrme forces of the type of sly4 predict @xmath0 around 230 mev, in agreement with the gogny force ( previous estimates using skyrme interactions having been plagued by lack of full self - consistency ) ; ( iii ) it is possible to build forces which predict @xmath0 around 250 mev, although part of this increase is due to our poor knowledge of the density dependence and effective mass.
the merger of two white dwarfs ( a.k.a.   double degenerate merger ) has often been cited as a potential progenitor of type ia supernovae. here   we combine population synthesis, merger and explosion models with radiation - hydrodynamics light - curve models to study the implications of such a progenitor scenario on the observed type ia supernova population. our standard model, assuming double degenerate mergers   do produce thermonuclear explosions, produces supernova light - curves that are broader than the observed type ia sample.   in addition, we discuss how the shock breakout and spectral features of these double degenerate progenitors will differ from the canonical bare chandrasekhar - massed explosion models.   we conclude with a discussion of how one might reconcile these differences with current observations.
a very brief status of next - to - leading order qcd calculations is given.   as an example the next - to - leading order qcd calculations to the @xmath0 processes at the cern large hardon collider are presented.   results for integrated and differential cross sections are shown.   they have been obtained in the framework of the helac - nlo system.
of concern in this paper is an investigation of heat and mass transfer over a stretching sheet under the influence of an applied uniform magnetic field and the effects of hall current are taken into account.   the non - linear boundary layer equations together with the boundary conditions are reduced to a system of non - linear ordinary differential equations by using the similarity transformation.   the system of non - linear ordinary differential equations are solved by developing a suitable numerical techniques such as finite difference scheme and newton s method of linearization.   the numerical results concerned with the velocity, temperature and concentration profiles as well as the skin - friction coefficient, local nusselt number @xmath0 and the local sherhood number @xmath1 for various values of the non - dimensional parameters presented graphically.   + * keywords : * hall current, magnetohydrodynamic, stretching sheet, skin - friction, heat transfer rate, chemical reaction    0.8 cm -.1 in -.1 in 0.0 cm 20.5 cm     definition observation  proposition rule    20.5 cm    = currsize
a graviton of a nonzero mass and decay width propagates five physical polarizations.   the question of interactions of these polarizations is crucial for viability of models of massive / metastable gravity.   this question is addressed in the context of the dgp model of a metastable graviton.   first, i argue that the well - known breakdown of a naive perturbative expansion at a low scale is an artifact of the weak - field expansion itself.   then, i propose a different expansion  the constrained perturbation theory  in which the breakdown does not occur and the theory is perturbatively tractable all the way up to its natural ultraviolet cutoff. in this approach   the couplings of the extra polarizations to matter and their selfcouplings appear to be suppressed and should be neglected in measurements at sub - horizon scales.   the model reproduces results of general relativity at observable distances with high accuracy, while predicting deviations from them at the present - day horizon scale.   nyu - th-04/03/22    0.9 cm    * weakly - coupled metastable graviton *    0.7 cm    gregory gabadadze    0.3 cm    _ center for cosmology and particle physics   _    _ department of physics, new york university, new york, ny, 10003, usa _    1.9 cm
we summarize the status of a `` targeted '' redshift survey aimed at establishing the properties of galaxies and their large scale distribution in the redshift range @xmath0. at the time of this writing, we have obtained spectra of more than 400 galaxies in in this redshift range, all identified using the `` lyman break '' color  selection technique.   we present some of the first results on the general clustering properties of the lyman break galaxies.   the galaxies are very strongly clustered, with co - moving correlation length similar to present  day galaxies, and they are evidently strongly biased relative to the mass distribution at these early epochs, which is consistent with hierarchical galaxy formation models if lyman break galaxies trace the most massive halos at @xmath1.   prospects for large surveys for galaxies beyond @xmath2 are discussed.
costas loop is a classical phase - locked loop ( pll ) based circuit for carrier recovery and signal demodulation.   the pll is an automatic control system that adjusts the phase of a local signal to match the phase of the input reference signal.   this tutorial is devoted to the dynamic analysis of the costas loop.   in particular the acquisition process is analyzed.   acquisition is most conveniently described by a number of frequency and time parameters such as lock - in range, lock - in time, pull - in range, pull - in time, and hold - in range. while for the classical pll equations   all these parameters have been derived ( many of them are approximations, some even crude approximations ), this has not yet been carried out for the costas loop.   it is the aim of this analysis to close this gap.   the paper starts with an overview on mathematical and physical models ( exact and simplified ) of the different variants of the costas loop.   then equations for the above mentioned key parameters are derived.   finally, the lock - in range of the costas loop for the case where a lead - lag filter is used for the loop filter is analyzed.   costas loop, nonlinear analysis, pll - based circuits, simulation, pull - in range, hold - in range, lock - in range
we present a theoretical description of excitons and positively and negatively charged trions in  giant  cdse / cds core - shell nanocrystals ( ncs ).   the developed theory provides the parameters describing the fine structure of excitons in cdse / cds core / thick shell ncs as a function of the cdse / cds conduction band offset and the cdse core radius.   we have also developed a general theory describing the fine structure of positively charged trions created in semiconductor ncs with a degenerate valence band.   the calculations take into account the complex structure of the cdse valence band and inter - particle coulomb and exchange interaction.   presented in this paper are the cdse core size and cdse / cds conduction band offset dependences ( i ) of the positively charged trion fine structure, ( ii ) of the binding energy of the negatively charged trion, and ( iii ) of the radiative decay time for excitons and trions.   the results of theoretical calculations are in qualitative agreement with available experimental data.   = by 60 = 255=255 by -60 by 255
we review the motivation for hidden higgs scenarios and discuss the light cp odd higgs scenario in the nmssm as an example.   we summarize experimental constraints including recent limits from babar and aleph.   the main part of the talk is the discussion of dominant decay modes of the standard model like higgs boson, and related decay modes of the charged higgs and heavy cp even higgs bosons, in these scenarios with the focus on signatures and prospects for the lhc.   examples include the direct production of a light cp odd higgs boson, and a light charged higgs boson in top quark decays.
we present the first microscopic images of the prewetting transition of a liquid film on a solid surface.   pictures of the local coverage map of a helium film on a cesium metal surface are taken while the temperature is raised through the transition.   the film edge is found to advance at constant temperature by successive avalanches in a creep motion with a macroscopic correlation length.   the creep velocity varies strongly in a narrow temperature range.   the retreat motion is obtained only at much lower temperature, conforming to the strong hysteresis observed for prewetting transition on a disordered surface.   prewetting transition on such disordered surfaces appears to give rise to dynamical phenomena similar to what is observed for domain wall motions in 2d magnets.
it is shown that three - dimensional systems of coupled quantum wires support fractional topological phases composed of closed loops and open planes of two - dimensional fractional quantum hall subsystems.   these phases have topologically protected edge states, and are separated by exotic quantum phase transitions corresponding to a rearrangement of fractional quantum hall edge modes. some support for the existence of an extended exotic critical phase separating the bulk gapped fractional topological phases is given. without electron - electron interactions, similar but unfractionalized bulk gapped phases based on coupled integer   quantum hall states exist.   they are separated by an extended critical weyl semimetal phase.
the cell formation problem has been studied as an optimization problem in manufacturing for more than 90 years.   it consists of grouping machines and parts into manufacturing cells in order to maximize loading of cells and minimize movement of parts from one cell to another.   many heuristic algorithms have been proposed which are doing well even for large - sized instances.   however, only a few authors have aimed to develop exact methods and most of these methods have some major restrictions such as a fixed number of production cells for example. in this paper   we suggest a new mixed - integer linear programming model for solving the cell formation problem with a variable number of manufacturing cells.   the popular grouping efficacy measure is used as an objective function. to deal with its fractional nature   we apply the dinkelbach approach.   our computational experiments are performed on two testsets : the first consists of 35 well - known instances from the literature and the second contains 32 instances less popular.   we solve these instances using cplex software.   optimal solutions have been found for 63 of the 67 considered problem instances and several new solutions unknown before have been obtained.   the computational times are greatly decreased comparing to the state - of - art approaches.   cell formation problem, cellular manufacturing, fractional objective, two - index model, grouping efficacy
we analyze the gamma - ray emission from 9 high latitude, translucent molecular clouds taken with the _ fermi _ large area telescope ( lat ) between 250 mev and 10 gev.   observations of gamma - rays allow us to probe the density and spectrum of cosmic rays in the solar neighborhood.   the clouds studied lie within @xmath0 pc from the sun and are selected from the _ planck _ all - sky co map.   gamma - rays in this energy range mostly result from cosmic ray interactions with the interstellar medium, which is traced with three components : hi, co, and dark gas. every cloud is detected and shows significant, extended gamma - ray emission from molecular gas.   the gamma - ray emission is dominated by the co - emitting gas in some clouds, but by the co - dark gas in others.   the average emissivity and gamma - ray power law index from hi  above 1 gev shows no evidence of a systematic variation.   the co - to-  conversion factor shows no variation between clouds over this small spatial range, but shows significant variations within each cloud.   the average co - to-  conversion factor suggests that the co - dark gas is molecular as opposed to optically thick hi.
tourism industry has grown tremendously in the previous several decades. despite its global impact,   there still remain a number of open questions related to better understanding of tourists and their habits. in this work   we analyze the largest data set of travel receipts considered thus far, and focus on exploring and modeling booking behavior of online customers.   we extract useful, actionable insights into the booking behavior, and tackle the task of predicting the booking time.   the presented results can be directly used to improve booking experience of customers and optimize targeting campaigns of travel operators.   = 10000 = 10000
the surface gravity of any killing horizon, in any spacetime dimension, can be interpreted as a local, two - dimensional expansion rate seen by freely falling observers when they cross the horizon.   any two - dimensional congruence of geodesics invariant under the killing flow can be used to define this expansion, provided that the observers have unit killing energy.   * horizon surface gravity as 2d geodesic expansion *    ted jacobson@xmath0 and renaud parentani@xmath1    0.5 cm    @xmath0department of physics    _ university of maryland _    college park, md 20742 - 4111, usa    0.5 cm    @xmath1laboratoire de physique thorique    _ cnrs umr 8627, universit paris - sud 11 _    91405 orsay cedex, france
based on consistent evolutionary and pulsation calculations, we analyse the effect of metallicity and of different convection treatments in the stellar models on period - magnitude, - color and - radius relationships. in order to perform an accurate comparison with observations, we have computed grids of atmosphere models and synthetic spectra for different metallicities, covering the range of effective temperatures and gravities relevant for cepheids.   the models are compared to recent observations of galactic and magellanic clouds cepheids  . unprecedented level of agreement is found between models and observations.   we show that within the range of metallicity for the galaxy and the magellanic clouds, a change of slope in the period - luminosity ( pl ) relationship is predicted at low periods, due to the reduction of the blue loop during core he burning.   the minimum mass undergoing a blue loop and consequently the critical period at which this change of slope occurs depend on the metallicity z and on the convection treatment in the stellar models.   however, besides this change of slope, we do not find any significant effect of metallicity on period - magnitude relationships from v to k bands, and on period - color relationships in ir colors.   we only find a detectable effect of @xmath0 on @xmath1 colors.   these results are not affected by uncertainties inherent to current stellar models, mainly due to convection treatment.
we extend the cobordism based categorification of the virtual jones polynomial to virtual tangles.   this extension is combinatorial and has semi - local properties.   we use the semi - local property to prove an applications, i.e. we give a discussion of lee s degeneration of virtual homology.   ( red ).   iff we have a double mismatch at the top and bottom, then we add a bolt symbol. ]
we present velocity - resolved reverberation results for five active galactic nuclei.   we recovered velocity - delay maps using the maximum - entropy method for four objects : mrk 335, mrk 1501, 3c120, and pg2130 + 099.   for the fifth, mrk  6, we were only able to measure mean time delays in different velocity bins of the h@xmath0  emission line.   the four velocity - delay maps show unique dynamical signatures for each object. for 3c120,   the balmer lines show kinematic signatures consistent with both an inclined disk and infalling gas, but the ii4686 heii@xmath1  emission line is suggestive only of inflow.   the balmer lines in mrk 335, mrk 1501, and pg2130 + 099 show signs of infalling gas, but the heii  emission in mrk 335 is consistent with an inclined disk.   we also see tentative evidence of combined virial motion and infalling gas from the velocity - binned analysis of mrk 6. the maps for 3c120 and mrk 335 are two of the most clearly defined velocity - delay maps to date.   these maps constitute a large increase in the number of objects for which we have resolved velocity - delay maps and provide evidence supporting the reliability of reverberation - based black hole mass measurements.
we discuss a toy model for an emergent non - relativistic gravitational theory. within a certain class of bose   einstein condensates, it is possible to show that, in a suitable regime, a modified version of non - relativistic newtonian gravity does effectively describes the low energy dynamics of the coupled system condensate / quasi - particles.
clusters of galaxies have an observed over - density of low - luminosity systems in comparison to the field, although it is not yet agreed whether this effect is the result of initial galaxy mass functions that vary with environment or galaxy evolutionary effects. in this letter   we argue that this over - density is the result of low - mass systems with red colors that are over - populating the faint - end of the observed luminosity function in the nearby rich cluster abell  0426.   we show that the luminosity function of abell  0426 becomes steeper, from the field value @xmath0 = -1.25@xmath10.05 to @xmath0=-1.44@xmath10.04, due to a recently identified population of red low - mass cluster galaxies that are possibly the remnants of dynamical stripped high - mass systems.   we further demonstrate, through simple models of stripping effects, how cluster luminosity functions can become artificially steep over time from the production of these low - mass cluster galaxies.
the recent findings of romanowsky et al.  , of an `` unexpectedly '' small mass discrepancy within 5 effective radii in several elliptical galaxies, are not surprising in the context of mond. as we show here  , they are, in fact, in full concordance with its predictions.   one is dealing with high - surface - density galaxies with mean accelerations rather larger than the acceleration constant of mond.   these findings continue, and are now the extreme examples of, the trend predicted by mond : the mass discrepancy sets in at larger and larger scaled radii in galaxies with larger and larger mean surface densities ; or, equivalently, mean accelerations.
we present the projected metallicity profiles for a sample of 17 rich galaxy clusters observed by bepposax. we find that the 8 non - cooling flow clusters have flat metallicity profiles. on the contrary, a strong enhancement in the abundance   is found in the central regions of the cooling flow clusters.   all the non - cooling flow clusters present evidence of recent merger activity suggesting that the merger events redistributes efficiently the metal content of the intracluster medium. for the cooling flow clusters with better statistics and available optical data ( a85, a496, a2029 and perseus ) we have tested whether the observed abundance excess is due to metals ejected from the galaxies located in the cluster core.   we find that at a resolution @xmath0 kpc the observed projected abundance excess profiles are consistent with originating from a deprojected metal excess distribution tracing the optical light distribution. in the one case ( i.e. perseus ) with higher resolution ( @xmath1 kpc ), we find that the observed metal abundance excess distribution is broader than the predicted one.   such a difference can be reconciled if we assume that the metals have drifted away from their parent ejecting galaxies by a few tens of kpc, or, alternatively, if we assume that the cluster light profile has become significantly more centrally peaked because of the formation process of the central dominant cluster galaxy since the last major merger occurred.
we demonstrate how to directly study non - abelian statistics for a wide class of exactly solvable many - body quantum systems. by employing exact eigenstates to simulate the adiabatic transport of a model s quasiparticles  , the resulting berry phase provides a direct demonstration of their non - abelian statistics.   we apply this technique to kitaev s honeycomb lattice model and explicitly demonstrate the existence of non - abelian ising anyons confirming the previous conjectures. finally, we present the manipulations needed to transport and detect the statistics of these quasiparticles in the laboratory.   various physically realistic system sizes are considered and exact predictions for such experiments are provided.
* preprint of : *    alexis i. bishop, timo a. nieminen, norman r. heckenberg, and halina rubinsztein - dunlop,    `` optical application and measurement of torque on microparticles of isotropic nonabsorbing material '',    _ physical review a _ * 68 *, 033802 ( 2003 )    we show how it is possible to controllably rotate or align microscopic particles of isotropic nonabsorbing material in a tem@xmath0 gaussian beam trap, with simultaneous measurement of the applied torque using purely optical means.   this is a simple and general method of rotation, requiring only that the particle is elongated along one direction.   thus, this method can be used to rotate or align a wide range of naturally occurring particles. the ability to measure   the applied torque enables the use of this method as a quantitative tool  the rotational equivalent of optical tweezers based force measurement. as well as being of particular value for the rotation of biological specimens,   this method is also suitable for the development of optically - driven micromachines.
recent numerical simulations have lead to a paradigm shift in our understanding of the intergalactic medium, and the loss of a physical justification for voigt profile fitting of the lyman - alpha forest.   many individual lines seen in simulated spectra have significant departures from the voigt profile, yet could be well fitted by a blend of two or more such lines.   we discuss the expected effect on the line profiles due to ongoing gravitational structure formation and hubble expansion.   we develop a method to detect departures from voigt profiles of the absorption lines in a statistical way and apply this method to simulated ly@xmath0   forest spectra, confirming that the profiles seen do statistically differ from voigt profiles.
the swimming velocity and rate of dissipation of a linear chain consisting of two or three little spheres and a big sphere is studied on the basis of low reynolds number hydrodynamics.   the big sphere is treated as a passive cargo, driven by the tail of little spheres via hydrodynamic and direct elastic interaction.   the fundamental solution of stokes equations in the presence of a sphere with no - slip boundary condition, as derived by oseen, is used to model the hydrodynamic interactions between the big sphere and the little spheres.
current - induced spin - transfer torques ( stts ) have been studied in fe, co and ni domain walls ( dws ) by the method based on the first - principles noncollinear calculations of scattering wave functions expanded in the tight - binding linearized muffin - tin orbital ( tb - lmto ) basis.   the results show that the out - of - plane component of nonadiabatic stt in fe dw has localized form, which is in contrast to the typical nonlocal oscillating nonadiabatic torques obtained in co and ni dws. meanwhile, the degree of nonadiabaticity in stt is also much greater for fe dw.   further, our results demonstrate that compared to the well - known first - order nonadiabatic stt, the torque in the third - order spatial derivative of local spin can better describe the distribution of localized nonadiabatic stt in fe dw.   the dynamics of local spin driven by this third - order torques in fe dw have been investigated by the landau - lifshitz - gilbert ( llg ) equation.   the calculated results show that with the same amplitude of stts the dw velocity induced by this third - order term is about half of the wall speed for the case of the first - order nonadiabatic stt.
currently, there are 24 black hole ( bh ) x - ray binary systems that have been dynamically confirmed in the galaxy.   most of them are low - mass x - ray binaries ( lmxbs ) comprised of a stellar - mass bh and a low - mass donor star.   although the formation of these systems has been extensively investigated, some crucial issues remain unresolved.   the most noticeable one is that, the low - mass companion has difficulties in ejecting the tightly bound envelope of the massive primary during the spiral - in process. while initially intermediate - mass binaries are more likely to survive the common envelope ( ce ) evolution, the resultant bh lmxbs mismatch the observations. in this paper  , we use both stellar evolution and binary population synthesis to study the evolutionary history of bh lmxbs.   we test various assumptions and prescriptions for the supernova mechanisms that produce bhs, the binding energy parameter, the ce efficiency, and the initial mass distributions of the companion stars.   we obtain the birthrate and the distributions of the donor mass, effective temperature and orbital period for the bh lmxbs in each case. by comparing the calculated results with the observations  , we put useful constraints on the aforementioned parameters.   in particular, we show that it is possible to form bh lmxbs with the standard ce scenario if most bhs are born through failed supernovae.       binaries : general @xmath0 black hole physics @xmath0 x - ray : binaries @xmath0 stars : evolution
we propose a numerical method for resummation of perturbative series, which is based on the stochastic perturbative solution of schwinger - dyson equations.   the method stochastically estimates the coefficients of perturbative series, and incorporates borel resummation in a natural way.   similarly to the `` worm '' algorithm, the method samples open feynman diagrams, but with an arbitrary number of external legs. as a test of our numerical algorithm,   we study the scale dependence of the renormalized coupling constant in a theory of one - component scalar field with quartic interaction.   we confirm the triviality of this theory in four and five space - time dimensions, and the instability of the trivial fixed point in three dimensions.
we study the effect of strong longitudinal color fields ( scf ) in @xmath0 reactions up to large hadron collider energies in the framework of the hijing / bb v2.0 model that combines ( collinear factorized ) pqcd multiple minijet production with soft longitudinal string excitation and hadronization.   the default vacuum string tension, @xmath1 = 1 gev / fm, is replaced by an effective energy dependent string tension, @xmath2 that increases monotonically with center - of - mass energy.   the exponent @xmath3 is found sufficient to reproduce well the energy dependence of multiparticle observables in rhic, tevatron, as well as recent lhc data.   this exponent is half of that predicted by the color glass saturation ( cgc ) model, @xmath4, where gluon fusion multiparticle production mechanisms are assumed. in hijing   / bb v2.0, the rapid growth of @xmath5 with energy is due to the interplay of copious minijet production with increasing of strong color field ( scf ) contributions.   the large ( strange)baryon - to - meson ratios measured at tevatron energies are well described. a significant enhancement of these ratios   is predicted up to the highest lhc energy ( 14 tev ).   the effect of jj loops and scf on baryon - anti - baryon asymmetry, and its relation to baryon number transport, is also discussed.
we investigate the effective properties ( conductivity, diffusivity and elastic moduli ) of model random composite media derived from gaussian random fields and overlapping hollow spheres.   the morphologies generated in the models exhibit low percolation thresholds and give a realistic representation of the complex microstructure observed in many classes of composites.   the statistical correlation functions of the models are derived and used to evaluate rigorous bounds on each property.   simulation of the effective conductivity is used to demonstrate the applicability of the bounds.   the key morphological features which effect composite properties are discussed.    2
current limits from the lhc on fourth generation quarks are already at the unitarity bound of 500 gev or so. if they exist, the strong yukawa couplings are turning nonperturbative, and may form bound states.   we study the domain of @xmath0 and @xmath1 in the range of 500 to 700 gev, where we expect binding energies are mainly of yukawa origin, with qcd subdominant. to be consistent with electroweak precision tests,   the @xmath2 and @xmath3 quarks have to be nearly degenerate, exhibiting a new  isospin ". comparing relativistic expansion with a relativistic bound state approach  , we find the most interesting is the production of a color octet, isosinglet vector meson ( a  gluon - prime " ) via @xmath4.   leading decay modes are @xmath5, @xmath6, and constituent quark decay, with @xmath7 and @xmath8 and @xmath9 subdominant.   the color octet, isovector pseudoscalar @xmath10 meson decays via constituent quark decay, or to @xmath11.   these decay rates are parameterized by the decay constant, the binding energy and mass differences, and @xmath12. for small @xmath13  , one could have a spectacular signal of @xmath14, where a soft @xmath15 accompanies a very massive @xmath11 pair.   in general, however, one has high multiplicity signals with @xmath16, @xmath15 and @xmath17 jet substructures that are not so different from @xmath18 and @xmath19 search.   pacs numbers : :    14.65.jk 11.10.st 13
this manuscript proposes a posterior mean ( pm ) super - resolution ( sr ) method with a compound gaussian markov random field ( mrf ) prior.   sr is a technique to estimate a spatially high - resolution image from observed multiple low - resolution images. a compound gaussian mrf model provides a preferable prior for natural images that preserves edges.   pm is the optimal estimator for the objective function of peak signal - to - noise ratio ( psnr ).   this estimator is numerically determined by using variational bayes ( vb ).   we then solve the conjugate prior problem on vb and the exponential - order calculation cost problem of a compound gaussian mrf prior with simple taylor approximations. in experiments,   the proposed method roughly overcomes existing methods.   super - resolution, fully bayesian approach, markov random field prior, variational bayes, taylor approximation.
the geometry of 4d simplicial quantum gravity with a u(1 ) gauge field is studied numerically.   the phase diagram shows a continuous transition when gravity is coupled with a u(1 ) gauge field. at the critical point measurements of the curvature distribution of @xmath0 space shows an inflated geometry with homogeneous and symmetric nature.   also, by choosing a 4-simplex and fixing the scalar curvature geometry of the space is measured.
quantum discord ( qd ) reveals the nonclassical nature of correlations in bipartite quantum states, going beyond the entanglement - separability paradigm. in this article   we discuss the suitability of qd in what concern its possible asymmetry with relation to the bipartition we choose to compute it.   we obtain an analytical formula for a symmetrized version of qd ( sqd ) in bell - diagonal states.   we observe that if correlation is regarded as a shared property, then the sqd could be a convenient quantifier for asymmetric states.   quantum information, entanglement, quantum discord
in this paper we explore a possibility that all transport turbulent models are contained in a coarse - grained kinetic equation.   building on a recent work by h.chen et al ( 2004 ), we account for fluctuations of a single -point probability density in turbulence, by introducing a``two - level '' ( @xmath0)-phase - space, separating microscopic ( @xmath1 ) and hydrodynamic ( @xmath2 ) modes. unlike traditional kinetic theories, with hydrodynamic approximations derived in terms of small deviations from thermodynamic equilibrium  , the theory developed in this work, is based on a far- from -equilibrium isotropic and homogeneous turbulence as an unperturbed state.   the expansion in dimensionless rate of strain leads to a new class of turbulent models, including the well - known @xmath3, reynolds stress and all possible nonlinear models.   the role of interaction of the fluxes in physical space with the energy flux across the scales, not present in standard modeling, is demonstrated on example of turbulent channel flow. to close the system, neither equation for turbulent kinetic energy nor information on pressure - velocity correlations, contained in the derived coarse - grained kinetic equation,   are needed.
an intriguing interpretation of the time - evolution of dynamical systems is to view it as a computation that transforms an initial state to a final one.   this paradigm has been explored in discrete systems such as cellular automata models, where the relation between dynamics and computation has been examined in detail.   here, motivated by microfluidic experiments on arrays of chemical oscillators, we show that computation can be achieved in continuous - state, continuous - time systems by using complex spatiotemporal patterns generated through a reaction - diffusion mechanism in coupled relaxation oscillators.   we present two paradigms that illustrate this computational capability, namely, using perturbations to ( i ) generate propagating configurations in a system of initially exactly synchronized oscillators, and ( ii ) transform one time - invariant pattern to another. in particular, we have demonstrated a possible implementation of nand logic.   this raises the possibility of universal computation in such systems as all logic gates can be constructed from nand gates.   our work suggests that more complex schemes can potentially implement arbitrarily complicated computation using reaction - diffusion processes, bridging pattern formation with universal computability.
we report the detection of a large glitch in the pulsar b0919 + 06 ( j0922 + 0638 ).   the glitch occurred in 2009 november 5 ( mjd 55140 ) and was characterized by a fractional increase in the rotation frequency of @xmath0.   a large glitch happens in the pulsar whose rotation has unstable character.   we present the results of the analysis of the rotation behavior of this pulsar over the 30-year time span from 1979 to 2009.   these results show that the pulsar s rotation frequency underwent continuous, slow oscillations which look like glitch - like events. during the 19912009 interval,   the pulsar experienced a continuous sequence of 12 slow glitches with a fractional increase in the rotation frequency @xmath1.   all the slow glitches observed have a similar signature related to a slow increase in the rotation frequency during @xmath2 200 days and the subsequent relaxation back to the pre - glitch value during @xmath2 400 days.   we show that a continuous sequence of such slow glitches is characterized by practically identical amplitudes @xmath3 hz and identical time intervals between glitches @xmath2 600 days and is well described by a periodic sawtooth - like function.   the detection of two different phenomena, such as a large glitch and a sequence of slow glitches, indicates the presence of two types of discontinuities in the rotation frequency of the pulsar b0919 + 06.   these discontinuities can be classified as normal and slow glitches.
to investigate new gauge boson @xmath0 phenomenology model - independent, we combine chiral effective theory with anomaly cancellation conditions without any other model input.   we focus on @xmath0 mixings with @xmath1 in both mass and kinetic parts and calculate contributions to oblique @xmath2.   the three sets of anomaly - free fermion @xmath3 charges parameterize the @xmath0 interactions with fermions.   the cancellation of the @xmath4 ^ 3 $ ] anomaly and mixing gravitational - gauge anomaly determines the number of right - handed neutrinos.   we also find a novel relation between the charge assignments and stueckelberg coupling in terms of the renormalized electromagnetic current.   a global fit to the electroweak precise observables shows that typical values for the mixing parameters are of order @xmath5. in spite of this strict limit,   we obtain a negative @xmath6 parameter contribution.   pacs numbers : 12.60.cn ; 14.70.pw ; 12.15 lk    key words : new gauge boson @xmath0 ; anomaly free ; chiral effective theory ; fit
we investigate the possibility that electrically neutral porous spheres electrophorese in electrolyte solutions with asymmetric affinity of ions to spheres on the basis of electrohydrodynamics and the poisson - boltzmann and debye - bueche - brinkman theories. assuming a weak electric field and ignoring the double - layer polarization  , we obtain analytical expressions for electrostatic potential, electrophoretic mobility, and flow field. in the equilibrium state, the galvani potential forms across the interface of the spheres. under a weak electric field,   the spheres show finite mobility with the same sign as the galvani potential.   when the radius of the spheres is significantly larger than the debye and hydrodynamic screening length, the mobility monotonically increases with increasing salinity.
the faint end of the differential galaxy number counts, @xmath0, in the hubble deep field ( hdf ) north has been determined for the f450w, f606w, and f814w filters by means of surface - brightness fluctuation ( sbf ) measurements.   this technique allows us to explore @xmath0 beyond the limiting magnitude of the hdf, providing new, stronger constraints on the faint end of @xmath0.   this has allowed us to test the validity of previous number count studies and to produce a new determination of the faint end of @xmath0 for magnitudes fainter than @xmath1 in the @xmath2 system and to extend this estimate down to @xmath3.   this value represents an extension of more than two magnitudes beyond the limits of previous photometric studies.   the obtained @xmath0 slopes are @xmath4, @xmath5, and @xmath6 in @xmath7, @xmath8, and @xmath9, respectively.
we performed mapping observations of the class i protostellar binary system l1551 ne in the c@xmath0o ( @xmath1=32 ), @xmath2co ( @xmath1=32 ), cs ( @xmath1=76 ), and so ( @xmath3=7@xmath46@xmath5 ) lines with atacama submillimeter telescope experiment ( aste ). the aste c@xmath0o data are combined with our previous sma c@xmath0o data, which show a @xmath6300-au scale keplerian disk around the protostellar binary system.   the c@xmath0o maps show a @xmath720000-au scale protostellar envelope surrounding the central keplerian circumbinary disk.   the envelope exhibits a northeast ( blue ) - southwest ( red ) velocity gradient along the minor axis, which can be interpreted as a dispersing gas motion with an outward velocity of 0.3 km s@xmath8, while no rotational motion in the envelope is seen.   in addition to the envelope, two @xmath94000 au scale, high - velocity ( @xmath101.3 km s@xmath8 ) redshifted @xmath2co and cs emission components are found to @xmath740@xmath11 southwest and @xmath720@xmath11 west of the protostellar binary.   these redshifted components are most likely outflow components driven from the neighboring protostellar source l1551 irs 5, and are colliding with the envelope in l1551 ne. the net momentum, kinetic and internal energies of the l1551 irs 5 outflow components are comparable to those of the l1551 ne envelope, and the interactions between the outflows and the envelope are likely to cause the dissipation of
a potential can have features that do not reflect the dynamics of the system it describes but rather arise from the choice of interpolating fields used to define it.   this is illustrated using a toy model of scattering with two coupled channels.   a bethe - salpeter amplitude is constructed which is a mixture of the waves in the two channels.   the potential derived from this has a strong repulsive core, which arises from the admixture of the closed channel in the wave function and not from the dynamics of the model.
we show that a discrete tight - binding model representing either a random or a quasiperiodic array of bonds, can have the entire energy spectrum or a substantial part of it absolutely continuous, populated by extended eigenfunctions only, when atomic sites are coupled to the lattice locally, or non - locally from one side  . the event can be fine - tuned by controlling only the host - adatom coupling in one case, while in two other cases cited here an additional external magnetic field is necessary.   the delocalization of electronic states for the group of systems presented here is sensitive to a subtle correlation between the numerical values of the hamiltonian parameters  a fact that is not common in the conventional cases of anderson localization.   our results are analytically exact, and supported by numerical evaluation of the density of states and electronic transmission coefficient.
we present the results of radio searches for pulsars within unidentified egret source error boxes. using the parkes multibeam system,   we have surveyed 56 sources at galactic latitudes @xmath0 which do not appear to be associated with blazars.   this population has been suggested to be distributed like the local star forming region known as the gould belt, the galactic halo, and/or the millisecond pulsars.   we have discovered several new pulsars in this survey, including three new binary systems.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
starting from the acv approach to transplanckian scattering, we present a development of the reduced - action model in which the ( improved ) eikonal representation is able to describe particles motion at large scattering angle and, furthermore, uv - safe ( regular ) rescattering solutions are found and incorporated in the metric.   the resulting particles shock - waves undergo calculable trajectory shifts and time delays during the scattering process  which turns out to be consistently described by both action and metric, up to relative order @xmath0 in the gravitational radius over impact parameter expansion.   some suggestions about the role and the ( re)scattering properties of irregular solutions  not fully investigated here  are also presented.
on january 2, the magic - i telescope observed grb090102 ( z=1.55 ) under particularly good observation conditions. using the recently upgraded magic-1 sum trigger system, upper limits down to below 50  gev   have been obtained.   this is the first time that the new trigger system was fully exploited for a gamma - ray burst ( grb ) observation and shows the capabilities of the magic observatory for future follow - up observations.   grb, iact, vhe
it has recently been suggested that the existence of bare strange stars is incompatible with low scale gravity scenarios.   it has been claimed that in such models, high energy neutrinos incident on the surface of a bare strange star would lead to catastrophic black hole growth.   we point out that for the flat large extra dimensional case, the parts of parameter space which give rise to such growth are ruled out by other methods.   we then go on to show in detail how black holes evolve in the the randall - sundrum two brane scenario where the extra dimensions are curved.   we find that catastrophic black hole growth does not occur in this situation either.   we also present some general expressions for the growth of five dimensional black holes in dense media.
we describe a general approach to quark flavor tagging in polarized hadronic processes, with particular emphasis on semi - inclusive deep inelastic scattering.   a formalism is introduced that allows one to relate chosen quark flavor polarizations to an arbitrary combination of final - state hadron spin asymmetries. within the context of the presented formalism  , we quantify the sensitivity of various semi - inclusive hadron asymmetries to the light quark flavors.   we show that _ unpolarized _ @xmath0 s may allow one to measure strange quark and antiquark polarizations independently.   we also highlight several applications of our formalism, particularly to measurements intended to probe further the spin structure of the nucleon.
we construct mixing processes over an infinite alphabet and ergodic processes over a  finite alphabet for which shannon mutual information between adjacent blocks of length @xmath0 grows as @xmath1, where @xmath2.   the processes are a  modification of nonergodic santa fe processes, which were introduced in the context of natural language modeling.   the rates of mutual information for the latter processes are alike and also established in this paper. as an auxiliary result  , it is shown that infinite direct products of mixing processes are also mixing.   + * key words * : direct products, ergodic processes, mixing, mutual information, variable length coding + * msc 2010 : * 37a25, 94a17 + * running head * : processes with rapidly growing information
we study the effect of cooling flows in galaxy clusters on the sunyaev - zeldovich ( sz ) distortion and the possible cosmological implications.   the sz effect, along with x - ray observations of clusters, is used to determine the hubble constant, @xmath0.   blank sky surveys of sz effect are being planned to constrain the geometry of the universe through cluster counts.   it is also known that a significant fraction of clusters has cooling flows in them, which changes the pressure profile of intracluster gas.   since the sz decrement depends essentially on the pressure profile, it is important to study possible changes in the determination of cosmological parameters in the presence of a cooling flow.   we build several representative models of cooling flows and compare the results with the corresponding case of gas in hydrostatic equilibrium.   we find that cooling flows can lead to an overestimation of the hubble constant.   specifically, we find that for realistic models of cooling flow with mass deposition ( varying @xmath1 with radius ), there is of the order @xmath2 deviation in the estimated value of the hubble constant ( from that for gas without a cooling flow ) even after excluding @xmath3 of the cooling flow region from the analysis.   we also discuss the implications of using cluster counts from sz observations to constrain other cosmological parameters, in the presence of clusters with cooling flows.
the synergy between the large hadron collider and the international linear collider during concurrent running of the two machines has the potential to maximise the physics gain from both facilities.   some examples of detailed case studies of the interplay between the lhc and ilc are given, with a particular emphasis on new results that have been obtained after the first lhc / ilc study group report was released.
broadband noise represents a severe limitation towards the implementation of a solid - state quantum information processor. considering common spectral forms  , we propose a classification of noise sources based on the effects produced instead of on their microscopic origin.   we illustrate a multi - stage approach to broadband noise which systematically includes only the relevant information on the environment, out of the huge parametrization needed for a microscopic description.   we apply this technique to a solid - state two - qubit gate in a fixed coupling implementation scheme.
short period sdb binaries with cool companions are crucial to understand pre - cv evolution, because they will evolve into cataclysmic variables, when the sdb will have left the extended horizontal branch.   recently we discovered the sixth such system, hs  2333 + 3927, consisting of an sdb star and an m dwarf ( period : 0.172  d ) with a very strong reflection effect, but no eclipses. the reflection is stronger than in any of the other similar systems which renders a quantitative spectral analysis very difficult because the balmer line profiles may be disturbed by the reflected light. a spectroscopic analysis results in @xmath0 = 36500k, @xmath1 = 5.70, and @xmath2.   mass - radius relations were derived from the results of the analysis of light and radial - velocity curves.   comparison with the mass - radius relation derived from the surface gravity of the sdb star favours a rather low mass of 0.38  for the primary. the mass of the companion is 0.29 .   hs  2333 + 3927 is the only known sdb+dm system with a period above the cv period gap.
typical protocols for peer - to - peer file sharing over the internet divide files to be shared into pieces.   new peers strive to obtain a complete collection of pieces from other peers and from a seed. in this paper   we investigate a problem that can occur if the seeding rate is not large enough.   the problem is that, even if the statistics of the system are symmetric in the pieces, there can be symmetry breaking, with one piece becoming very rare.   if peers depart after obtaining a complete collection, they can tend to leave before helping other peers receive the rare piece. assuming that peers arrive with no pieces  , there is a single seed, random peer contacts are made, random useful pieces are downloaded, and peers depart upon receiving the complete file, the system is stable if the seeding rate ( in pieces per time unit ) is greater than the arrival rate, and is unstable if the seeding rate is less than the arrival rate. the result persists for any piece selection policy that selects from among useful pieces, such as rarest first, and it persists with the use of network coding.
we consider approaches to cosmological parameter estimation in the inflationary cosmology, focussing on the required accuracy of the initial power spectra. parametrizing the spectra, for example by power - laws,   is well suited to testing the inflationary paradigm but will only correctly estimate cosmological parameters if the parametrization is sufficiently accurate, and we investigate conditions under which this is achieved both for present data and for upcoming satellite data.   if inflation is favoured, reliable estimation of its physical parameters requires an alternative approach adopting its detailed predictions. for slow - roll inflation, we investigate the accuracy of the predicted spectra at first and second order in the slow - roll expansion ( presenting the complete second - order corrections for the tensors for the first time ).   we find that within the presently - allowed parameter space, there are regions where it will be necessary to include second - order corrections to reach the accuracy requirements of _ map _ and _ planck _ satellite data.   we end by proposing a data analysis pipeline appropriate for testing inflation and for cosmological parameter estimation from high - precision data.
we report the discovery of millisecond oscillations in the x - ray emission from the x - ray transient sax j1750.8 - 2900.   millisecond quasiperiodic oscillations ( khz qpos ) were present in the persistent emission with frequencies ranging from 543  hz to 1017  hz.   oscillations at a frequency of 600.75  hz were present in the brightest x - ray burst observed.   we derive an upper limit on the source distance of @xmath0 from this x - ray burst.
we study the electronic structure of a spherical jellium in the presence of a central gaussian impurity.   we test how well the resulting inhomogeneity effects beyond spherical jellium are reproduced by several approximations of density functional theory ( dft ).   four rungs of perdew s ladder of dft functionals, namely local density approximation ( lda ), generalized gradient approximation ( gga ), meta - gga and orbital - dependent hybrid functionals are compared against our quantum monte carlo ( qmc ) benchmarks.   we identify several distinct transitions in the ground state of the system as the electronic occupation changes between delocalized and localized states.   we examine the parameter space of realistic densities ( @xmath0 ) and moderate depths of the gaussian impurity ( @xmath1 ).   the selected 18 electron system ( with closed - shell ground state ) presents @xmath2 transitions while the 30 electron system ( with open - shell ground state ) exhibits @xmath3 transitions. for the former system  , the accuracy for the transitions is clearly improving with increasing sophistication of functionals with meta - gga and hybrid functionals having only small deviations from qmc.   however, for the latter system, we find much larger differences for the underlying transitions between our pool of dft functionals and qmc.   we attribute this failure to treatment of the exact exchange within these functionals.   additionally, we amplify the inhomogeneity effects by creating the system with spherical shell which leads to even larger errors in dft approximations.
we try to interpret the recently updated measurement of the cosmic ray electron ( cre ) spectrum observed by fermi - lat, together with pamela data on positron fraction, in a single - component scenario adopting different propagation setups ; we find that the model is not adequate to reproduce the two datasets, so the evidence of an extra primary component of electrons and positrons is strengthened.   instead, a double component scenario computed in a kraichnan - like diffusion setup ( which is suggested by b / c and @xmath0 data ) gives a satisfactory fit of all exisiting measurements.   we confirm that nearby pulsars are good source candidates for the required @xmath1 extra - component and we show that the predicted cre anisotropy in our scenario is compatible with fermi - lat recently published constraints.
we study the effect of wave function orthogonality in the relativistic treatment of the nucleon removal reactions @xmath0 and @xmath1.   the continuum wave function describing the outgoing nucleon is made orthogonal to the relevant bound states using the gram - schmidt procedure.   this procedure has the advantage of preserving the asymptotic character of the continuum wave function and hence the elastic observables are unaffected.   the orthogonality effects are found to be negligible for @xmath1 reactions for missing momenta up to 700 @xmath2.   this holds true for both parallel and perpendicular kinematics.   by contrast the orthogonalization of the wave functions appears to have a more pronounced effect in the case of @xmath0 reactions.   we find that the orthogonality effect can be significant in this case particularly for large angles.   polarization of the outgoing protons and photon asymmetry show more sensitivity than the cross sections.   if the orthogonality condition is imposed solely on this one hole state the effects are usually smaller.
the thermal nucleation of quark matter bubbles inside neutron stars is examined for various temperatures which the star may realistically encounter during its lifetime.   it is found that for a bag constant less than a critical value, a very large part of the star will be converted into the quark phase within a fraction of a second.   depending on the equation of state for neutron star matter and strange quark matter, all or some of the outer parts of the star may subsequently be converted by a slower burning or a detonation.   nucleation of quark matter bubbles in neutron stars    institute of physics and astronomy, aarhus university, dk-8000 rhus c, denmark    to be published in phys.   rev.
' '' ''   the renormalization of the chiral np interaction in the @xmath0 channel to n3lo in weinberg counting for the long distance potential with one single momentum and energy independent counterterm is carried out.   this renormalization scheme yields finite and unique results and is free of short distance off - shell ambiguities.   we observe good convergence in the entire elastic range below pion production threshold and find that there are some small physical effects missing in the purely pionic chiral nn potential with or without inclusion of explicit @xmath1 degrees of freedom.   we also study the renormalizability of the standard weinberg counting at nlo and n2lo when a momentum dependent polynomial counterterm is included.   our numerical results suggest that the inclusion of this counterterm does not yield a convergent amplitude ( at nlo and n2lo ).
we study relaxation times, also called mixing times, of quantum many - body systems described by a lindblad master equation.   we in particular study the scaling of the spectral gap with the system length, the so - called dynamical exponent, identifying a number of transitions in the scaling. for systems with bulk dissipation   we generically observe different scaling for small and for strong dissipation strength, with a critical transition strength going to zero in the thermodynamic limit.   we also study a related phase transition in the largest decay mode. for systems with only boundary dissipation   we show a generic bound that the gap can not be larger than @xmath0  . in integrable systems with boundary dissipation one typically observes scaling @xmath1, while in chaotic ones one can have faster relaxation with the gap scaling as @xmath0 and thus saturating the generic bound.   we also observe transition from exponential to algebraic gap in systems with localized modes.
one interpretation of how the classical world emerges from an underlying quantum reality involves the build - up of certain robust entanglements between particles due to scattering events @xcite.   this is an appealing view because it unifies two apparently disparate theories.   it says that the uniquely quantum effect of entanglement is associated with classical behaviour.   this is distinct from other interpretations that says classicality arises when quantum correlations are lost or neglected in measurements. to date the weakness of this interpretation has been the lack of a clear experimental signature that allows it to be tested. here we provide a simple experimentally accessible scheme that enables just that.   we also discuss a bayesian technique that could, in principle, allow experiments to confirm the theory to any desired degree of accuracy and we present precision requirements that are achievable with current experiments.   finally, we extend the scheme from its initial one dimensional proof of principle to the more real world scenario of three dimensional localisation.
we consider sputtering of dust grains, believed to be formed in cooling supernovae ejecta, under the influence of reverse shocks. in the regime of self - similar evolution of reverse shocks  , we can follow the evolution of ejecta density and temperature analytically as a function of time in different parts of the ejecta, and calculate the sputtering rate of graphite and silicate grains embedded in the ejecta as they encounter the reverse shock. through analytic ( 1d ) calculations,   we find that a fraction of dust mass ( @xmath0% for silicates and graphites ) can be sputtered by reverse shocks, the fraction varying with the grain size distribution and the steepness of the density profile of the ejecta mass.   it is expected that many more grains will get sputtered in the region between the forward and reverse shocks, so that our analytical results provide a lower limit to the destroyed fraction of dust mass.
a topological insulator and its spin analog as a gapped spin liquid have characteristic low energy excitations ( edge states ) within the gap when the systems have boundaries.   this is the bulk - edge correspondence, which implies that the edge states themselves characterize the gapped bulk spin liquid.   based on the general principle, we analyzed the vector chirality and rung singlet phases of the spin-@xmath0 ladder with ring exchange by using the edge states and the entanglement entropy.
during the past month we have been trying to understand both the behavior of csma / eca and how our simulator works. in this report   i try to asses some of those doubts and provide a groundwork for discussion of past and new ideas for further develop the mac protocol.
astrophysical implications of neutrino mass and mixings are discussed.   the status of solar and atmospheric neutrino problems, and recent developments concerning nuclear physics input to solar models and solar opacities are reviewed.   implications of neutrino mass and mixings in supernova dynamics are explored.   the effects of supernova density fluctuations in neutrino propagation is described.
we discuss fragmentation mechanisms and isospin transport occurring in central collisions between neutron rich systems at fermi energies.   in particular, isospin effects are analyzed looking at the correlations between fragment isotopic content and kinematical properties.   simulations are based on an approximate solution of the boltzmann - langevin ( bl ) equation.   an attempt to solve the complete bl equation, by introducing full fluctuations in phase space is also discussed.   multifragmentation, isospin transport, symmetry energy, fluctuations, many - body approaches    25.70.pq, 25.70.-z, 21.30.fe
in the present work, the analytical description of an intermolecular vibrational energy transfer, analyzed by two dimensional infrared spectroscopy, is established.   the energy transfer process takes place between the dark combination states of low frequency modes pertaining to different molecules.   the appearance of the cross peaks results from coherent transfer between these combination states and an optically active state of the acceptor molecule.   such a process has recently been observed experimentally between the nitrile groups of acetonitrile-@xmath0 and benzonitrile molecules.   this molecular system will be used as a model for the simulations of their two - dimensional infrared spectra.   the dependence of the cross - peak growth, which is a signature of the intermolecular energy transfer, will be discussed in detail as a function of the molecular dynamical constants.
for ultracold and bose - condensed atoms contained in periodic optical potential wells the quantized nature of their motion is clearly visible.   the motion of the atomic wavepacket can also be accurately controlled. for those systems the long - range character of the atomic interaction and of the external potential play a key role in the quantum mechanical evolution.   the basic facets of the experimental and theoretical research for atoms within optical lattice structures will be reviewed.
cold debris disks trace the limits of planet formation or migration in the outer regions of planetary systems, and thus have the potential to answer many of the outstanding questions in wide - orbit planet formation and evolution.   we characterized the infrared excess spectral energy distributions of 174 cold debris disks around 546 main - sequence stars observed by both _   spitzer _   irs and mips.   we found a trend between the temperature of the inner edges of cold debris disks and the stellar type of the stars they orbit.   this argues against the importance of strictly temperature - dependent processes ( e.g. non - water ice lines ) in setting the dimensions of cold debris disks. also, we found no evidence that delayed stirring causes the trend. the trend may result from outward planet migration that traces the extent of the primordial protoplanetary disk, or it may result from planet formation that halts at an orbital radius limited by the efficiency of core accretion.
we study thermodynamic of strange quark matter ( sqm ) using the analytic expressions of free and internal energies.   we investigate two regimes of the high density and low density separately. as a vital program, in the case of a massless gluon and massless quarks at finite temperature, we also present a geometry of thermodynamics for the gluon and bosons using a legendre invariance metric, it is so called as geometrothermodynamic ( gtd ) to better understanding of the phase transition.   the gtd metric and its second order scalar invariant have been obtained, and we clarify the phase transition by study the singularities of the scalar curvature of this riemannian metric.   this method is ensemble dependence and to complete the phase transition.   meanwhile, we also investigate enthalpy and entropy and internal energy representations.   our work exposes new pictures of the nature of phase transitions in sqm.
analysis of a database of solar coronal mass ejections ( cmes ) and associated flares over the period 1996 - 2007 finds well - behaved power law relationships between the 18    flare x - ray fluence and cme mass and kinetic energy.   we extrapolate these relationships to lower and higher flare energies to estimate the mass and energy loss due to cmes from stellar coronae, assuming that the observed x - ray emission of the latter is dominated by flares with a frequency as a function of energy @xmath0. for solar - like stars at saturated levels of x - ray activity, the implied losses depend fairly weakly on the assumed value of @xmath1 and are very large : @xmath2  yr@xmath3 and @xmath4. in order to avoid such large energy requirements  , either the relationships between cme mass and speed and flare energy must flatten for x - ray fluence @xmath5  erg, or the flare - cme association must drop significantly below 1 for more energetic events.   if active coronae are dominated by flares, then the total coronal energy budget is likely to be up to an order of magnitude larger than the canonical @xmath6 x - ray saturation threshold.   this raises the question of what is the maximum energy a magnetic dynamo can extract from a star? for an energy budget of 1%  of @xmath7, the cme mass loss rate is about @xmath8  yr@xmath3.
we calculate the force of a quasicircularly polarized guided light field of a nanofiber on a dielectric spherical particle.   we show that the orbital parts of the axial and azimuthal components of the poynting vector are always positive while the spin parts can be either positive or negative.   we find that, for appropriate values of the size parameter of the particle, the azimuthal component of the force is directed oppositely to the circulation direction of the energy flow around the nanofiber.   the occurrence of such a negative azimuthal force indicates that the particle undergoes a negative torque.
we demonstrate that a stochastic model consistent with the scaling properties of financial assets is able to replicate the empirical statistical properties of the s&p 500 high frequency data within a window of three hours in each trading day.   this result extends previous findings obtained for eur / usd exchange rates.   we apply the forecast capabilities of the model to implement an explicit trading strategy.   trading signals are model - based and not derived from chartist criteria. in - sample and out - of - sample tests indicate that the model performs better than a benchmark asymmetric garch process, and expose the existence of small arbitrage opportunities.   we discuss how to improve performances and why the trading strategy is potentially interesting to hedge volatility risk for s&p index - based products.   anomalous scaling ; memory ; intraday returns ; intraday strategy.
_ the problem of time synchronization in dense wireless networks is considered.   well established synchronization techniques suffer from an inherent scalability problem in that synchronization errors grow with an increasing number of hops across the network. in this work, a model for communication in wireless networks   is first developed, and then the model is used to define a new time synchronization mechanism.   a salient feature of the proposed method is that, in the regime of asymptotically dense networks, it can average out all random errors and maintain global synchronization in the sense that all nodes in the multi - hop network can see identical timing signals.   this is irrespective of the distance separating any two nodes. _   ( 0,0 ) ( 0,78)to appear in the ieee transactions on information theory.   cooperation in networks, large network asymptotics, relay networks, scalability, sensor networks, time synchronization, wireless communications.
an extreme dissipation event in the bulk of a closed three - dimensional turbulent convection cell is found to be correlated with a strong reduction of the large - scale circulation flow in the system that happens at the same time as a plume emission event from the bottom plate.   the reduction in the large - scale circulation opens the possibility for a nearly frontal collision of down- and upwelling plumes and the generation of a high - amplitude thermal dissipation layer in the bulk.   this collision is locally connected to a subsequent high - amplitude energy dissipation event in the form of a strong shear layer.   our analysis illustrates the impact of transitions in the large - scale structures on extreme events at the smallest scales of the turbulence, a direct link that is observed in a flow with boundary layers.   we also show that detection of extreme dissipation events which determine the far - tail statistics of the dissipation fields in the bulk requires long - time integrations of the equations of motion over at least hundred convective time units.
this paper presents a detailed analysis of two - armed spiral structure in a sample of galaxies from the spitzer infrared nearby galaxies survey ( sings ), with particular focus on the relationships between the properties of the spiral pattern in the stellar disc and the global structure and environment of the parent galaxies.   following paper i we have used a combination of spitzer space telescope mid - infrared imaging and visible multi - colour imaging to isolate the spiral pattern in the underlying stellar discs, and we examine the systematic behaviours of the observed amplitudes and shapes ( pitch angles ) of these spirals. in general,   spiral morphology is found to correlate only weakly at best with morphological parameters such as stellar mass, gas fraction, disc / bulge ratio, and v@xmath0.   in contrast to weak correlations with galaxy structure a strong link is found between the strength of the spiral arms and tidal forcing from nearby companion galaxies.   this appears to support the longstanding suggestion that either a tidal interaction or strong bar is a necessary condition for driving grand - design spiral structure.   the pitch angles of the stellar arms are only loosely correlated with the pitch angles of the corresponding arms traced in gas and young stars.   we find that the strength of the shock in the gas and the contrast in the star formation rate are strongly correlated with the stellar spiral amplitude.       galaxies : individual  galaxies : spiral  galaxies : structure  infrared : galaxies
we present _ suzaku _ observations of the galactic black hole candidate swift j1753.5 - 0127  in the low - hard state.   the broadband coverage of suzaku enables us to detect the source over the energy range 0.6  250 kev.   the broadband spectrum ( 2  250 kev ) is found to be consistent with a simple power - law ( @xmath0 1.63 ). in agreement with previous observations of this system,   a significant excess of soft x - ray flux is detected consistent with the presence of a cool accretion disc.   estimates of the disc inner radius infer a value consistent with the isco ( @xmath1, for certain values of, e.g. @xmath2 ), although we can not conclusively rule out the presence of an accretion disc truncated at larger radii ( @xmath3 ). a weak  , relativistically - broadened iron line is also detected, in addition to disc reflection at higher energy.   however, the iron - k line profile favours an inner radius larger than the isco ( r@xmath4 ).   the implications of these observations for models of the accretion flow in the low - hard state are discussed.
using the experimental data from the alice program on the centrality dependence of the transverse momentum ( @xmath0 ) spectra in pb+pb collisions at @xmath1 tev, we show that the double - tsallis distribution and the generalized fokker - plank ( fp ) solution can not describe the spectra of pions, kaons and protons from central to peripheral collisions in the entire @xmath0 region, simultaneously.   hence, a new two - component distribution, which is a hydrodynamic extension of the generalized fp solution accounting for the collective motion effect in heavy - ion collisions, is proposed in order to reproduce all the particle spectra.   our results suggest that the particle production dynamics may be different for different particles, especially at very low @xmath0 region.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 ).
a quantum monte carlo algorithm for the transverse ising model with arbitrary short- or long - range interactions is presented.   the algorithm is based on sampling the diagonal matrix elements of the power series expansion of the density matrix ( stochastic series expansion ), and avoids the interaction summations necessary in conventional methods. in the case of long - range interactions, the scaling of the computation time with the system size @xmath0   is therefore reduced from @xmath1 to @xmath2.   the method is tested on a one - dimensional ferromagnet in a transverse field, with interactions decaying as @xmath3.
we present a theoretical study of the collective optical effects which can occur in groups of three and four quantum dots.   we define conditions for stable subradiant ( dark ) states, rapidly decaying superradiant states, and spontaneous trapping of excitation.   each quantum dot is treated like a two - level system.   the quantum dots are though realistic, meaning that they may have different transition energies and dipole moments.   the dots interact via a short - range coupling which allows excitation transfer across the dots, but conserves the total population.   we calculate the time evolution of single- and biexciton states using the linblad equation. in the steady state   the individual populations of each dot may have permanent oscillations with frequencies given by the energy separation between the subradiant eigenstates.
estimates of the gas temperature in planetary nebulae obtained from the  emission line ratio and from the balmer discontinuity indicate differences reaching up to 6000 k ( liu and danziger 1993 ).   the  temperature is commonly used to obtain the ionic fractions of highly ionized ions, particularly the o@xmath0 and ne@xmath0 ions when using the empirical method to calculate the elemental abundances of photoionized gas from the observed emission line intensities. however,   if the gas temperature is overestimated, the elemental abundances may be underestimated. in particular  , it may lead to an incorrect elemental abundance gradient for the galaxy, usually used as a constraint for the chemical evolution models. using monte carlo simulations  , we calculate the systematic error introduced in the abundance gradient obtained from planetary nebulae by an overestimation of the gas temperature.   the results indicate that the abundance gradient in the galaxy should be steeper than previously assumed.   .
we undertook searches for isolated galaxies based on automatic selection of infrared sources from the two micron all - sky survey ( 2mass ) followed by a visual inspection of their surrounding. using a modified criterion by karachentseva ( 1973 )  , we compiled a catalog of 3227 isolated galaxies ( 2mig ) containing 6% of 2mass extended sources ( 2masx ) brighter than @xmath0 with angular diameters @xmath1.   the most isolated 2493 galaxies among them enter in the 2mass very isolated galaxy catalog, 2mvig. being situated in the regions of extremely low mass density, the 2mvig galaxies can serve as a reference sample for investigation the influence of environment on structure and evolution of galaxies.
we review observational tests for the homogeneity of the universe on large scales.   redshift and peculiar velocity surveys, radio sources, the x - ray background, the lyman-@xmath0 forest and the cosmic microwave background are used to set constraints on inhomogeneous models and in particular on fractal - like models. assuming the cosmological principle and the frw metric  , we estimate cosmological parameters by joint analysis of peculiar velocities, the cmb, cluster abundance, iras and supernovae. under certain assumptions   the best fit density parameter is @xmath1.
we analyse the proposal of sliding phases ( sp ) in layers hosting global u(1 ) symmetric variables with finite inter - layer josephson coupling. based on the kosterlitz - thouless renormalization group ( rg ) approach,   such phases were predicted to exist in various layered ( or 1d quantum coupled ) systems.   the key in the rg argument is treating the coupling as though the variables are non - compact.   large scale monte carlo simulations of a layered model, where the sp is supposed to exist, finds no indication of such a phase. instead, 3d behavior is observed.   this result is consistent with the asymptotically exact analytical solution.   a generic argument against sp in translationally invariant systems with short range interactions is provided.   we have also suggested an alternative model for the sp  adding long - range interactions to the inter - layer josephson term.
we consider theories where the standard model ( sm ) neutrinos acquire masses through the seesaw mechanism at the weak scale.   we show that in such a scenario, the requirement that any pre - existing baryon asymmetry, regardless of its origin, not be washed out leads to correlations between the pattern of sm neutrino masses and the spectrum of new particles at the weak scale, leading to definite predictions for the lhc. for type i seesaw models with a tev scale @xmath0   coupled to sm neutrinos, we find that for a normal neutrino mass hierarchy, at least one of the right - handed neutrinos must be ` electrophobic ', decaying with a strong preference into final states with muons and tauons rather than electrons. for inverted or quasi - degenerate mass patterns, on the other hand, we find upper bounds on the mass of at least one right - handed neutrino. in particular, for an inverted mass hierarchy, this bound is 1 tev, while the corresponding upper limit in the quasi - degenerate case is 300 gev.   similar results hold in type iii seesaw models, albeit with somewhat more stringent bounds. for the type ii seesaw case with a weak scale @xmath1 triplet higgs  , we again find that an interesting range of higgs triplet masses is disallowed by these considerations.
motivated by theoretical predictions that first stars were predominantly very massive, we investigate the physics of the transition from an early epoch dominated by massive pop  iii stars to a later epoch dominated by familiar low - mass pop  ii / i stars by means of a numerically - generated catalogue of dark matter halos coupled with a self - consistent treatment of chemical and radiative feedback. depending on the strength of the chemical feedback, pop  iii stars can contribute a substantial fraction ( several percent ) of the cosmic star formation activity even at moderate redshifts, @xmath0.   we find that the three @xmath1 sources tentatively detected in nicmos udfs should be powered by pop  iii stars, if these are massive ; however, this scenario fails to reproduce the derived wmap electron scattering optical depth.   instead, both the udfs and wmap constraints can be fulfilled if stars at any time form with a more standard, slightly top - heavy, larson imf in the range @xmath2.   = = = = = = = =    # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn @mathgroup@bold@groupeurbn @mathgroup@group @mathgroup@normal@groupmsamn @mathgroup@bold@groupmsamn = `` 019 ='' 016 = `` 040 ='' 336 = " 33e = = = = = = = =    # 1 # 1 # 1 # 1 = = = = = = = =        galaxies : formation - cosmology : theory - cosmology : observations - intergalactic medium
let @xmath0 be a compact, oriented surface with negative euler characteristic and let @xmath1 be a homeomorphism isotopic to the identity. if there exists a periodic orbit with a non - zero rotation vector @xmath2, then there exists a simple braid with the same rotation vector.
miniboone charge current quasi - elastic double differential cross section data are analyzed and confronted with predictions of two theoretical nucleus models : fermi gas and spectral function.   the fitting procedure includes the overall flux uncertainty multiplicative factor. in order to obtain a reliable value of the axial mass, bins with large contribution from small momentum transfer   are eliminated from the analysis.   it is shown that the best fit axial mass value becomes smaller as the momentum transfer cut is more restrictive. for @xmath0  mev / c the obtained values of axial mass are @xmath1  mev for the fermi gas and @xmath2  mev for the spectral function.   the value @xmath3  mev is excluded on the level which goes far beyond @xmath4.
the scalar particle production from vacuum in the presence of an electric field, on the de sitter spacetime is studied.   we use perturbation methods to define the transition amplitude.   we obtain that the momentum is not conserved in this process.   the probability density of pair production is computed by squaring the transition amplitude.   our graphical representations show that, the probability of scalar particle production was important only in the early stages of the universe, when hubble s constant was very large in comparison with the mass of the particle. also we propose here a criterion for particle - antiparticle separation.
* the binding of a transcription factor ( tf ) to a dna operator site can initiate or repress the expression of a gene. computational prediction of sites recognized by a tf   has traditionally relied upon knowledge of several cognate sites, rather than an _ ab initio _ approach. here  , we examine the possibility of using structure - based energy calculations that require no knowledge of bound sites but rather start with the structure of a protein - dna complex.   we study the purr _   e. coli _ tf, and explore to which extent atomistic models of protein - dna complexes can be used to distinguish between cognate and non - cognate dna sites.   particular emphasis is placed on systematic evaluation of this approach by comparing its performance with bioinformatic methods, by testing it against random decoys and sites of homologous tfs.   we also examine a set of experimental mutations in both dna and the protein. using our explicit estimates of energy,   we show that the specificity for purr is dominated by direct protein - dna interactions, and weakly influenced by bending of dna. *   protein - dna interaction, transcription - factor binding sites, gene regulation, mutant binding site prediction, _ purr _
we present an overview of recent developments in numerical relativity studies of higher dimensional spacetimes with a focus on time evolutions of black - hole systems.   after a brief review of the numerical techniques employed for these studies, we summarize results grouped into the following three areas : ( i ) numerical studies of fundamental properties of black holes, ( ii ) applications of black - hole collisions to the modeling of trans - planckian scattering, ( iii ) numerical studies of asymptotically anti - de sitter spacetimes in the context of the gauge - gravity duality.
we consider the possibility of observing a parity violating but @xmath0 conserving interaction in the symmetry breaking sector of the electroweak theory. we find that the best probe for such an interaction is a forward - backward asymmetry in @xmath1 production from polarized @xmath2 collisions.   an observable asymmetry would be strong evidence against a custodial @xmath3 symmetry.   we also discuss the effects of such an interaction in future @xmath4 colliders as well as in rare decays of @xmath5 and @xmath6 mesons.    0.0 in 0.0 in 6.0 in 8.75 in -1.0 in.5 in # 1tr ( # 1 ) # 1#2#3_phys.   rev.   _ * d#1 * # 2 ( 19#3 ) # 1#2#3_phys.   lett. _ * # 1b * # 2 ( 19#3 ) # 1#2#3_nucl.   phys. _ * b#1 * # 2 ( 19#3 ) # 1#2#3_phys.   rev.   lett. _ * # 1 * # 2 ( 19#3 )    = -0.5 in    fermilab   pub93/218t + july, 1993    * signals for parity violation in the + electroweak symmetry breaking sector * +   * and g.  valencia@xmath7 * + _ @xmath8 physics department, brookhaven national laboratory, upton, ny 11973 _ + _ @xmath9 theoretical physics, fermi national accelerator laboratory, batavia, il 60510 _ + _ @xmath10 department of physics, iowa state university, ames, ia 50011 _ +
we calculate the zero temperature conductance and characteristic correlation functions of a molecule with a center of mass ( cm ) motion which modulates couplings to the leads. in   the first model studied, the cm vibrational mode is simultaneously coupled to the electron density on the molecule.   the conductance is suppressed in regimes corresponding to non - integer occupancy of the molecule. in the second model, where   the cm mode is not directly coupled to the electron density, the suppression of conductance is related to the dynamic breaking of the inversion symmetry.
the quantum critical antiferromagnetic ( afm ) fluctuation spectra measured by inelastic neutron scattering recently in two heavy fermion superconductors are used together with their other measured properties to calculate their d - wave superconducting transition temperatures @xmath0.   to this end, the linearized eliashberg equations for d - wave superconductivity induced by afm fluctuations are solved in models of fermions with various levels of nesting.   the results for the ratio of @xmath0 to the characteristic spin - fluctuation energy are well parametrized by a dimensionless coupling constant and the afm correlation length.   comparing the results with experiments suggests that one may reasonably conclude that superconductivity in these compounds is indeed caused by afm fluctuations.   this conclusion is strengthened by a calculation with the same parameters of the measured coefficient of the normal state quantum - critical resistivity @xmath1 characteristic of _ gaussian _ afm quantum - critical fluctuations.   the calculations give details of the superconducting coupling as a function of the correlation length and the integrated fluctuation spectra useful in other compounds.
changing the form of the star cluster mass function ( cmf ) can effectively change the upper end of the stellar initial mass function.   the yields of from supernovae are very sensitive to the mass of the progenitor star.   we show that by changing the parameters of the cmf, it is possible to change the yields of oxygen and magnesium by a factor of @xmath0 and of metals in general by a factor of @xmath1.       stars : formation  stars : abundances  galaxies : abundances
the energy spectra of quasi - one dimensional quasiperiodic ladder networks are analyzed within a tight binding description. in particular, we show that if a selected set of sites in each strand of a ladder is tunnel - coupled to quantum dots attached from a side, absolutely continuous subbands can be generated in the spectrum if one tunes the dot potential and the dot - strand coupling appropriately.   typical cases with two and three strand fibonacci ladders in the off diagonal model are discussed in details.   we also discuss the possibility of re - entrant insulator - metal transition for a general @xmath0-strand ladder network when @xmath0 becomes large.   the observations remain valid even in the case of a disordered ladder network with the same constituents.   the results are analytically exact.
we present and discuss a detailed derivation of a new analytical method that systematically improves the convergence of path integrals of a generic @xmath0-fold discretized theory.   we develop an explicit procedure for calculating a set of effective actions @xmath1, for @xmath2 which have the property that they lead to the same continuum amplitudes as the starting action, but that converge to that continuum limit ever faster.   discretized amplitudes calculated using the @xmath3 level effective action differ from the continuum limit by a term of order @xmath4.   we obtain explicit expressions for the effective actions for levels @xmath5.   we end by analyzing the speedup of monte carlo simulations of two different models : an anharmonic oscillator with quartic coupling and a particle in a modified pschl - teller potential.
we have studied the electron transport through a quantum dot coupled to three leads in the presence of external microwave fields supplied to different parts of the considered mesoscopic system.   additionally, we introduced a possible nonresonant tunneling channels between leads.   the quantum dot charge and currents were determined in terms of the appropriate evolution operator matrix elements and under the wide band limit the analytical formulas for time - averaged currents and differential conductance were obtained.   we have also examined the response of the considered system on the rectangular - pulse modulation imposed on different quantum dot - leads barriers as well as the time - dependence of currents flowing in response to suddenly removed ( or included ) connection of a quantum dot with one of the leads.    * photon - assisted electron transport through a three - terminal quantum dot system with nonresonant tunneling channels *    t. kwapiski, r. taranko, e. taranko +    institute of physics, maria curie - skodowska university, + and + maria curie - skodowska university nanotechnology center + 20 - 031 lublin, poland
we prove that every bounded rational space curve of degree @xmath0 and circularity @xmath1 can be drawn by a linkage with @xmath2 revolute joints.   our proof is based on two ingredients.   the first one is the factorization theory of motion polynomials.   the second one is the construction of a motion polynomial of minimum degree with given orbit.   our proof also gives the explicity construction of the linkage.
for a parabolic surface partial differential equation coupled to surface evolution, convergence of the spatial semidiscretization is studied in this paper.   the velocity of the evolving surface is not given explicitly, but depends on the solution of the parabolic equation on the surface.   various velocity laws are considered : elliptic regularization of a direct pointwise coupling, a regularized mean curvature flow and a dynamic velocity law.   a novel stability and convergence analysis for evolving surface finite elements for the coupled problem of surface diffusion and surface evolution is developed.   numerical experiments complement the theoretical results.
many astronomical objects are surrounded by dusty environments. in such dusty objects,   multiple scattering processes of photons by circumstellar ( cs ) dust grains can effectively alter extinction properties. in this paper  , we systematically investigate effects of multiple scattering on extinction laws for steady - emission sources surrounded by the dusty cs medium, using a radiation transfer simulation based on the monte carlo technique.   in particular, we focus on whether and how the extinction properties are affected by properties of cs dust grains, adopting various dust grain models. we confirm that behaviors of the ( effective ) extinction laws are highly dependent on the properties of cs grains.   especially, the total - to - selective extinction ratio @xmath0, which characterizes the extinction law, can be either increased or decreased, compared to the case without multiple scattering.   we find that the criterion for this behavior is given by a ratio of albedos in the @xmath1 and @xmath2 bands.   we also find that either small silicate grains or polycyclic aromatic hydrocarbons ( pahs ) are necessary for realizing a low value of @xmath0 as often measured toward type ia supernovae, if the multiple scattering by cs dust is responsible for their non - standard extinction laws.   using the derived relations between the properties of dust grains and the resulting effective extinction laws, we propose that the extinction laws toward dusty objects could be used to constrain the properties of dust grains in cs environments.
we prove a conjecture of cohn and propp, which refines a conjecture of bosley and fidkowski about the symmetry of the set of alternating sign matrices ( asms ).   we examine data arising from the representation of an asm as a collection of paths connecting @xmath0 vertices and show it to be invariant under the dihedral group @xmath1 rearranging those vertices, which is much bigger than the group of symmetries of the square.   we also generalize conjectures of propp and wilson relating some of this data for different values of @xmath2.
surnames and nonrecombining alleles are inherited from a single parent in a highly similar way  . a simple birth - death model with mutations can accurately describe this process. exponentially growing and constant populations are investigated, and we study how different compositions of the founder populations can be observed in present - day diversity distributions.   we analyse different quantities in the statistically stationary state, both through analytic and numerical methods.   our results compare favourably to field data for family sizes in several countries.   we discuss the relationship between the distribution of surnames and the genetic diversity of a population.  .2 in
quantum coherence ( qch ) is considered to be a key ingredient in quantum resource theories and also plays a pivotal role in the design and implementation of various information processing tasks.   consequently, it becomes important for us to create more number coherent quantum states between two labs from a given coherent state shared initially.   we call this process as * broadcasting of quantum coherence ( qch)*. in this work we extensively study the problem of broadcasting of qch. in order to have a holistic view of broadcasting, we start with a most general representation two qubit mixed state in terms of bloch vectors. as a cloning transformation   we have used universal symmetric optimal buzek - hillery ( bh ) cloner locally as well as non locally.   remarkably, we find that in either of the case it is impossible to do optimal broadcasting of qch.   further we show in case of non optimal broadcasting it is impossible to increase qch of the state by both local and non local cloning operations. in non optimal case,   apart from general result we consider examples like, a ) werner like states ( wls ) and b ) bell diagonal states ( bds ) and obtain ranges for broadcasting in terms of input state parameters.
convolutional neural networks ( cnns ) perform well on problems such as handwriting recognition and image classification. however, the performance of the networks is often limited by budget and time constraints, particularly when trying to train deep networks.   motivated by the problem of online handwriting recognition, we developed a cnn for processing spatially - sparse inputs ; a character drawn with a one - pixel wide pen on a high resolution grid looks like a sparse matrix. taking advantage of   the sparsity allowed us more efficiently to train and test large, deep cnns. on the casia - olhwdb1.1 dataset containing 3755 character classes   we get a test error of 3.82%.   although pictures are not sparse, they can be thought of as sparse by adding padding.   applying a deep convolutional network using sparsity has resulted in a substantial reduction in test error on the cifar small picture datasets : 6.28% on cifar-10 and 24.30% for cifar-100.   * keywords : * online character recognition, convolutional neural network, sparsity, computer vision
we investigate the appearance of @xmath0 lapses in the transmission phase @xmath1 of a two - level quantum dot with coulomb interaction @xmath2. using the numerical and functional renormalization group methods we study the entire parameter space for spin - polarized as well as spin - degenerate dots, modeled by spinless or spinful electrons, respectively.   we investigate the effect of finite temperatures @xmath3. for small @xmath3 and sufficiently small single - particle spacings @xmath4 of the dot levels we find @xmath0 phase lapses between two transmission peaks in an overwhelming part of the parameter space of the level - lead couplings. for   large @xmath4 the appearance or not of a phase lapse between resonances depends on the relative sign of the level - lead couplings in analogy to the @xmath5 case.   we show that this generic scenario is the same for spin - polarized and spin - degenerate dots.   we emphasize that in contrast to dots with more levels, for a two - level dot with small @xmath4 and generic dot - lead couplings ( that is up to cases with special symmetry ) the `` universal '' phase lapse behavior is already established at @xmath5.   the most important effect of the coulomb interaction is to increase the separation of the transmission resonances.   the relation of the appearance of phase lapses to the inversion of the population of the dot levels is discussed. for the spin - polarized case and low temperatures   we compare our results to recent mean - field studies. for small @xmath4 correlations   are found to strongly alter the mean - field picture.
parametric down - conversion ( pdc ) offers the possibility to control the fabrication of non - gaussian states such as fock states.   however, in conventional pdc sources energy and momentum conservation introduce strict frequency and photon number correlations, which impact the fidelity of the prepared state. in our work   we optimize the preparation of single - photon fock states from the emission of waveguided pdc via spectral filtering.   we study the effect of correlations via photon number resolving detection and quantum interference.   our measurements show how the reduction of mixedness due to filtering can be evaluated. interfering the prepared photon with a coherent state   we establish an experimentally measured fidelity of the produced target state of 78%.
the cdex-1 experiment conducted a search of low - mass ( @xmath0 10 gev / c@xmath1 ) weakly interacting massive particles ( wimps ) dark matter at the china jinping underground laboratory using a p - type point - contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 evee.   we report the hardware set - up, detector characterization, data acquisition and analysis procedures of this experiment. no excess of unidentified events are observed after subtraction of known background. using 335.6 kg - days of data, exclusion constraints on the wimp - nucleon spin - independent and spin - dependent couplings   are derived.
properties of polyelectrolytes in tetravalent salt solutions are intensively investigated by a coarse - grained model.   the concentration of salt and the size of tetravalent counterions are found playing a decisive role on chain properties.   if the size of tetravalent counterions is compatible with the one of monomers, the chains show extended structures at low and at high salt concentrations, whereas at intermediate salt concentrations, they acquire compact and prolate structures.   the swelling exponent of a chain against salt concentration behaves in an analogous way as the morphological quantities. under certain condition,   the electrostatics gives a negative contribution to the persistence length, in companion with a salt - induced mechanical instability of polyelectrolytes. nearly at the same moment  , it appears like - charge attraction between chains.   the equal size of the tetravalent ions and the monomers is the optimal condition to attain the strongest attraction between chains and the most compact chain structure.   moreover, the ions form a multi - layer organization around a chain and, thus, the integrated charge distribution reveals an oscillatory behavior.   the results suggest that charge inversion has no direct connection with redissolution of polyelectrolytes at high salt concentrations.
the broad iron line in mcg-6 - 30 - 15 is fitted to the comptonization model where line broadening occurs due to compton down - scattering in a highly ionized optically thick cloud.   these results are compared to the disk line model where the broadening is due to gravitational / doppler effects in the vicinity of a black hole.   we find that both models fit the data well and it is not possible to differentiate between them by fitting only the asca data.   the best fit temperature and optical depth of the cloud are found to be @xmath0 kev and @xmath1 from the comptonization model.   this model further suggests that while the temperature can be assumed to be constant, the optical depth varies during the observation period.   we emphasis an earlier conclusion that simultaneous broad band data ( @xmath2 kev ) can rule out ( or confirm ) the comptonization model.
we two had year - long research leaves in japan, working together fulltime with several japanese plus tony de groot back in livermore and harald posch in vienna.   we summarize a few of the high spots from that very productive year ( 1989 - 1990 ), followed by an additional fifteen years work in livermore, with extensive travel.   next came our retirement in nevada in 2005, which has turned out to be a long - term working vacation.   carol narrates this part of our history together.
we study the tilt of the primordial gravitational waves spectrum. a hint of blue tilt   is shown from analyzing the bicep2 and polarbear data. motivated by this  , we explore the possibilities of blue tensor spectra from the very early universe cosmology models, including null energy condition violating inflation, inflation with general initial conditions, and string gas cosmology, etc. for the simplest g - inflation  , blue tensor spectrum also implies blue scalar spectrum.   in general, the inflation models with blue tensor spectra indicate large non - gaussianities. on the other hand,   string gas cosmology predicts blue tensor spectrum with highly gaussian fluctuations.   if further experiments do confirm the blue tensor spectrum, non - gaussianity becomes a distinguishing test between inflation and alternatives.   = 1
the thermodynamic properties of the electron gas in multilayer graphene depend strongly on the number of layers and the type of stacking. here   we analyse how those properties change when we vary the number of layers for rhombohedral stacked multilayer graphene and compare our results with those from a conventional two dimensional electron gas.   we show that the highly degenerate zero energy landau level which is partly filled with electrons and partly with holes has a strong influence on the value of the different thermodynamic quantities.
molecular dynamics simulations were used to determine the binding affinities between the hormone 17@xmath0-estradiol ( e2 ) and different estrogen receptor ( er ) isoforms in the rainbow trout, _ oncorhynchus mykiss_. previous phylogenetic analysis indicates that a whole genome duplication prior to the divergence of ray - finned fish led to two distinct er@xmath0 isoforms, er@xmath1 and er@xmath2, and the recent whole genome duplication in the ancestral salmonid created two er@xmath3 isoforms, er@xmath4 and er@xmath5.   the objective of our computational studies is to provide insight into the underlying evolutionary pressures on these isoforms. for the er@xmath3 subtype   our results show that e2 binds preferentially to er@xmath4 over er@xmath6.   tests of lineage specific @xmath7n/@xmath7s ratios indicate that the ligand binding domain of the er@xmath5 gene is evolving under relaxed selection relative to all other er@xmath3 genes.   comparison with the highly conserved dna binding domain suggests that er@xmath5 may be undergoing neofunctionalization possibly by binding to another ligand.   by contrast, both er@xmath8 and er@xmath2 bind similarly to e2 and the best fitting model of selection indicates that the ligand binding domain of all er@xmath0 genes are evolving under the same level of purifying selection, comparable to er@xmath4.
in this paper we connect degenerations of fano threefolds by projections. using mirror symmetry we transfer these connections to the side of landau  ginzburg models. based on   that we suggest a generalization of kawamata s categorical approach to birational geometry enhancing it via geometry of moduli spaces of landau  ginzburg models.   we suggest a conjectural application to hasset  kuznetsov  tschinkel program based on new nonrationality `` invariants '' we consider   gaps and phantom categories.   we make several conjectures for these invariants in the case of surfaces of general type and quadric bundles.
the transport properties of diluted magnetic semiconductors ( dms ) are calculated using dynamical mean field theory ( dmft ) and boltzmann transport theory.   within dmft we study the density of states and the dc - resistivity, which are strongly parameter dependent such as temperature, doping, density of the carriers, and the strength of the carrier - local impurity spin exchange coupling.   characteristic qualitative features are found distinguishing weak, intermediate, and strong carrier - spin coupling and allowing quantitative determination of important parameters defining the underlying ferromagnetic mechanism.   we find that spin - disorder scattering, formation of bound state, and the population of the minority spin band are all operational in dmft in different parameter range.   we also develop a complementary boltzmann transport theory for scattering by screened ionized impurities.   the difference in the screening properties between paramagnetic ( @xmath0 ) and ferromagnetic ( @xmath1 ) states gives rise to the temperature dependence ( increase or decrease ) of resistivity, depending on the carrier density, as the system goes from the paramagnetic phase to the ferromagnetic phase.   the metallic behavior below @xmath2 for optimally doped dms samples can be explained in the boltzmann theory by temperature dependent screening and thermal change of carrier spin polarization.   pacs numbers : 75.50.pp, 75.10.-b, 75.30.hx, 75.20.hr
we report detection of the 609  @xmath0 @xmath1 line of neutral atomic carbon in globules of the helix nebula.   the measurements were made towards the position of peak co emission. at the same position  , we obtained high - quality co(21 ) and @xmath2co(21 ) spectra and a 135@xmath3 map in co(21 ).   the velocity distribution of ci shows six narrow ( 12  km  s@xmath4 ) components which are associated with individual globules traced in co. the ci column densities are 0.51.2@xmath510@xmath6@xmath7.   ci is found to be a factor of @xmath86 more abundant than co. the large abundance of ci in the helix can be understood as a result of the gradual photoionisation of the molecular envelope by the central star s radiation field.   = cmr10    # 1#2
we describe the first dna - based storage architecture that enables random access to data blocks and rewriting of information stored at arbitrary locations within the blocks.   the newly developed architecture overcomes drawbacks of existing read - only methods that require decoding the whole file in order to read one data fragment.   our system is based on new constrained coding techniques and accompanying dna editing methods that ensure data reliability, specificity and sensitivity of access, and at the same time provide exceptionally high data storage capacity. as a proof of concept, we encoded parts of the wikipedia pages of six universities in the usa, and selected and edited parts of the text written in dna corresponding to three of these schools.   the results suggest that dna is a versatile media suitable for both ultrahigh density archival and rewritable storage applications.
a novel genetic algorithm is described that is suitable for determining the global minimum energy configurations of crystal structures and which can also be used as a polymorph search technique.   this algorithm requires no prior assumptions about unit cell size, shape or symmetry, nor about the ionic configuration within the unit cell.   this therefore enables true _   ab initio _ crystal structure and polymorph prediction.   our new algorithm uses a real - space representation of the population members, and makes use of a novel periodic cut for the crossover operation.   results on large lennard - jones systems with fcc- and hcp - commensurate cells show robust convergence to the bulk structure from a random initial assignment and an ability to successfully discriminate between competing low enthalpy configurations.   results from an _ ab initio _ carbon polymorph search show the spontaneous emergence of both lonsdaleite and graphite like structures.
recent studies have shown that outflows in at least some broad absorption line ( bal ) quasars are extended well beyond the putative dusty torus.   such outflows should be detectable in obscured quasars.   we present four wise selected infrared red quasars with very strong and peculiar ultraviolet feii emission lines : strong uv feii uv arising from transitions to ground / low excitation levels, and very weak feii at wavelengths longer than 2800.   the spectra of these quasars display strong resonant emission lines, such as civ, aliii and mgii but sometimes, a lack of non - resonant lines such as ciii ], siii and heii.   we interpret the feii lines as resonantly scattered light from the extended outflows that are viewed nearly edge - on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not.   we show that dust free gas exposed to strong radiation longward of 912   produces feii emission very similar to that observed.   the gas is too cool to collisionally excite feii lines, accounting for the lack of optical emission.   the spectral energy distribution from the uv to the mid - infrared can be modeled as emission from a clumpy dusty torus, with uv emission being reflected / scattered light either by the dusty torus or the outflow. within this scenario, we estimate a minimum covering factor of the outflows from a few to 20 percent for the feii scattering region, suggesting that feii bal quasars are at a special stage of quasar evolution.
fast variability studies of accreting black holes in the galaxy offer us a unique opportunity to measure the spins of black holes and test the strong - field behavior of general relativity. in this review,   i summarize the arguments often used in attempts of measuring the spins of black holes, concentrating on their theoretical foundations.   i also argue that x - ray studies of accreting black holes will be able to provide in the future strong constraints on deviations from general relativity in the strong - field regime.   address = physics department, university of arizona, 1118 e. 4th st.,   tucson, az 85721
despite a rich diversity in observational properties, gamma - ray bursts ( grbs ) can be divided into two broad categories based on their duration and spectral hardness  the long - soft and the short - hard grbs.   the discovery of afterglows from long grbs in 1997, and their localization to arcsecond accuracy, was a watershed event.   the ensuing decade of intense study led to the realization that long - soft grbs are located in star forming galaxies, produce about @xmath0 erg in collimated relativistic ejecta, are accompanied by supernovae, and result from the death of massive stars. while theoretical arguments suggest that short grbs have a different physical origin, the lack of detectable afterglows prevented definitive conclusions   the situation changed dramatically starting in may 2005 with the discovery of the first afterglows from short grbs localized by _ swift _ and _ hete-2_. here i summarize the discovery of these afterglows and the underlying host galaxies, and draw initial conclusions about the nature of the progenitors and the properties of the bursts.   address = carnegie observatories, pasadena, ca
we have analyzed h@xmath0 fabry - perot interferograms of ngc 5457 ( m101 ) in order to calculate the rotation curve.   we have also isolated a sample of 263 hii regions and we determined for each one its radial velocity and velocity dispersion.   the rotation curve agrees with previous determinations and the mass derived from it is 9.8@xmath1 10@xmath2 m@xmath3.   the distribution of velocity dispersion values of the hii regions presents a normal behavior, with a mean value of 30 km sec@xmath4.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
this is a survey of the electrostatic potentials produced by charged straight - line segments, in various numbers of spatial dimensions, with comparisons between uniformly charged segments and those having non - uniform linear charge distributions that give rise to ellipsoidal equipotentials surrounding the segments.   a uniform linear distribution of charge is compatible with ellipsoidal equipotentials only for three dimensions.  in higher dimensions,   the linear charge density giving rise to ellipsoidal equipotentials is counter - intuitive  the charge distribution has a maximum at the center of the segment and vanishes at the ends of the segment.  only in two dimensions   is the continuous charge distribution intuitive  for that one case of ellipsoidal equipotentials, the charge is peaked at the ends of the segment and minimized at the center.
a prediction of standard big bang cosmology is that the observed uhecr ( ultra - high - energy cosmic rays ) spectrum will exhibit a cutoff at the gkz limit, resulting from interaction with the photons that constitute the cosmic microwave background.   we show that for the quasi - static universe ( qsu ) model, in which photon energy is an invariant in the cosmological reference frame, the photon number density in the universe today is a factor of @xmath0 less than in the standard model. as a consequence,   the mean free path of uhecrs will exceed the horizon distance of the universe, rendering it essentially transparent to uhecrs.   the qsu model therefore predicts that no cutoff will be observed in the uhecr spectrum.
it is claimed that radiative corrections maintain the proportionality between the neutrino mass and the neutrino - majoron coupling and never give rise to enhanced decay rates in conventional majoron models.   the coupling of a majoron to neutrinos is calculated at one loop level in various models, including the singlet majoron model and the zee model with a majoron. when the respective corrections to the mass matrix are taken into account the would - be non - diagonal terms in the neutrino - majoron coupling are rotated away.   it is pointed out that the coincidence between neutrino mass matrices and neutrino - majoron couplings is not accidental, but is a general consequence of nther s theorem.   nther s theorem also implies that the majoron coupling to charged fermions is always diagonal in the fermion mass basis, and it vanishes completely in the singlet majoron models.
we present new results from a continuing 5 ghz search for flaring radio emission from a sample of l and t brown dwarfs, conducted with the 305-m arecibo radio telescope.   in addition to the previously reported flaring from the t6.5-dwarf 2mass j10475385 + 212423, we have detected and confirmed circularly polarized flares from another t6-dwarf, wisepc j112254.73 + 255021.5.   although the flares are sporadic, they appear to occur at a stable period of 0.288 hours. given the current constraints, periods equal to its second and third subharmonic can not be ruled out.   the stability of this period over the 8-month timespan of observations indicates that, if real, it likely reflects the star s rapid rotation. if confirmed, any of the three inferred periodicities would be much shorter than the shortest, 1.41-hour rotation period of a brown dwarf measured so far.   this finding would place a new observational constraint on the angular momentum evolution and rotational stability of substellar objects.   the detection of radio emission from the sixth @xmath01000 k dwarf further demonstrates that the coolest brown dwarfs and, possibly, young giant planets, can be efficiently investigated using radio observations at centimeter wavelengths as a tool.
the next generation advanced actpol ( advact ) experiment is currently underway and will consist of four transition edge sensor ( tes ) bolometer arrays, with three operating together, totaling @xmath05800 detectors on the sky. building on experience   gained with the actpol detector arrays, advact will utilize various new technologies, including 150  mm detector wafers equipped with multichroic pixels, allowing for a more densely packed focal plane.   each set of detectors includes a feedhorn array of stacked silicon wafers which form a spline profile leading to each pixel.   this is then followed by a waveguide interface plate, detector wafer, back short cavity plate, and backshort cap.   each array is housed in a custom designed structure manufactured from high purity copper and then gold plated.   in addition to the detector array assembly, the array package also encloses cryogenic readout electronics.   we present the full mechanical design of the advact high frequency ( hf ) detector array package along with a detailed look at the detector array stack assemblies.   this experiment will also make use of extensive hardware and software previously developed for act, which will be modified to incorporate the new advact instruments.   therefore, we discuss the integration of all advact arrays with pre - existing actpol infrastructure.
we have carried out an extensive radio study with the very large array on the seyfert 1.5 galaxy mrk  6 and imaged a spectacular radio structure in the source.   the radio emission occurs on three different spatial scales, from @xmath07.5  kpc bubbles to @xmath01.5  kpc bubbles lying nearly orthogonal to them and a @xmath01  kpc radio jet lying orthogonal to the kpc - scale bubble. to explain the complex morphology  , we first consider a scenario in which the radio structures are the result of superwinds ejected by a nuclear starburst.   however, recent spitzer observations of mrk  6 provide an upper limit to the star formation rate ( sfr ) of @xmath1  yr@xmath2, an estimate much lower than the sfr of @xmath3  yr@xmath2 derived assuming that the bubbles are a result of starburst winds energized by supernovae explosions.   thus, a starburst alone can not meet the energy requirements for the creation of the bubbles in mrk  6.   we show that a single plasmon model is energetically infeasible, and we argue that a jet - driven bubble model while energetically feasible does not produce the complex radio morphologies.   finally, we consider a model in which the complex radio structure is a result of an episodically - powered precessing jet that changes its orientation.   this model is the most attractive as it can naturally explain the complex radio morphology, and is consistent with the energetics, the spectral index and the polarization structure.   radio emission in this scenario is a short - lived phenomenon in the lifetime of a seyfert galaxy which results due to an accretion event.
following the 12 gev upgrade, a dedicated experiment is planned with the hall b clas12 detector at jefferson lab, with the aim to study electroproduction of nucleon resonances at high photon virtualities up to @xmath0  gev@xmath1. in this work we present a qcd - based approach to the theoretical interpretation of these upcoming results in the framework of light - cone sum rules that combine perturbative calculations with dispersion relations and duality.   the form factors are thus expressed in terms of @xmath2 light - front wave functions at small transverse separations, called distribution amplitudes.   the distribution amplitudes can therefore be determined from the comparison with the experimental data on form factors and compared to the results of lattice qcd simulations.   the results of the corresponding next - to - leading order calculation are presented and compared with the existing data.   we find that the form factors are dominated by the twist - four distribution amplitudes that are related to the @xmath3-wave three - quark wave functions of the @xmath2, i.e. to contributions of orbital angular momentum.
identifying the importance of nodes of complex networks is of interest to the research of social networks, biological networks etc.. current researchers have proposed several measures or algorithms, such as betweenness, pagerank and hits etc., to identify the node importance.   however, these measures are based on different aspects of properties of nodes, and often conflict with the others. a reasonable, fair standard is needed for evaluating and comparing these algorithms.   this paper develops a framework as the standard for ranking the importance of nodes.   four intuitive rules are suggested to measure the node importance, and the equivalence classes approach is employed to resolve the conflicts and aggregate the results of the rules. to quantitatively compare the algorithms, the performance indicators   are also proposed based on a similarity measure.   three widely used real - world networks are used as the test - beds.   the experimental results illustrate the feasibility of this framework and show that both algorithms, pagerank and hits, perform well with bias when dealing with the tested networks.   furthermore, this paper uses the proposed approach to analyze the structure of the internet, and draws out the kernel of the internet with dense links.   equivalence classes, node importance, dominance relationship, complex network, similarity measure
we have refined the estimate of the primordial level of @xmath0li abundance to an accuracy better than 10%, based on high - precision li abundances for metal - poor halo stars, and a recent model of post - bbn ( big bang nucleosynthesis ) chemical evolution that provides a quantitative explanation of the detected gentle ascent of the spite plateau for stars with metallicities @xmath1.   our maximum likelihood analysis obtains an estimate for the primordial li abundance of @xmath2, after taking into account possible systematic errors in the estimation of li abundances, with the exception of a still - controversial issue regarding stellar depletion.   the inferred value of @xmath3 ( the baryon - to - photon number - density ratio in the universe ) based on this estimate is more consistent with that derived from the set of reported `` low he '' + `` high d '' from extragalactic sites than that derived from reported `` high he '' + `` low d '' measurements.   since, within current models of stellar depletion processes, it is difficult to account for the observed very small scatter of li abundance in metal - poor stars, our estimate of @xmath4 should be taken as an independent constraint on the baryonic mass density parameter in the universe, giving @xmath5 with @xmath6 km s@xmath7mpc@xmath7.
we interpret magnetic billiards as finsler ones and describe an analog of the string construction for magnetic billiards.   finsler billiards for which the law  angle of incidence equals angle of reflection " are described.   we characterize the finsler metrics in the plane whose geodesics are circles of a fixed radius.   this is a magnetic analog of hilbert s fourth problem asking to describe the finsler metrics whose geodesics are straight lines.   _ msc _ : 53b40, 53c60, 53c65, 70f35    _ key words _ : magnetic flows, magnetic billiards, finsler metrics, finsler billiards, hilbert s fourth problem, pompeiu problem, integral geometry
we report on the development of a gem - based tpc prototype for the panda experiment.   the design and requirements of this device will be illustrated, with particular emphasis on the properties of the recently tested gem - detector, the characterization of the read - out electronics and the development of the tracking software that allows to evaluate the gem - tpc data.
a recent study has claimed that the rotation curve shapes and mass densities of low surface brightness ( lsb ) galaxies are largely consistent with @xmath0cdm predictions, in contrast to a large body of observational work.   i demonstrate that the method used to derive this conclusion is incapable of distinguishing the characteristic steep cdm mass - density distribution from the core - dominated mass - density distributions found observationally : even core - dominated pseudo - isothermal haloes would be inferred to be consistent with cdm.   this method can therefore make no definitive statements on the ( dis)agreement between the data and cdm simulations. after introducing an additional criterion that does take the slope of the mass - distribution into account i find that only about a quarter of the lsb galaxies investigated are possibly consistent with cdm.   however, for most of these the fit parameters are so weakly constrained that this is not a strong conclusion.   only 3 out of 52 galaxies have tightly constrained solutions consistent with @xmath0cdm.   two of these galaxies are likely dominated by stars, leaving only one possible dark matter dominated, cdm - consistent candidate, forming a mere 2 per cent of the total sample.   these conclusions are based on comparison of data and simulations at identical radii and fits to the entire rotation curves.   lsb galaxies that are consistent with cdm simulations, if they exist, seem to be rare indeed.
the celeste atmospheric cherenkov detector ran until june 2004.   it has observed the blazars mrk  421, 1es  1426 + 428 and mrk  501.   we significantly improved our understanding of the atmosphere using a lidar, and of the optical throughput of the detector using stellar photometry.   the new data analysis provides better background rejection.   we present our light curve for mrk  421 for the 2002 - 2004 season and a comparison with x - ray data and the 2004 observation of 1es  1426 + 428.   the new analysis will allow a more sensitive search for a signal from mrk  501.   celeste, cherenkov, mrk  421,1es  1426 + 428,mrk  501 95.85.pw, 98.54.cm
we generalize the earlier theory by fredrickson [ j. rheol. *   38 *, 1045 ( 1994 ) ] to study the orientational behaviour of the hexagonal phase of diblock copolymer melt subjected to steady shear flow.   we use symmetry arguments to show that the orientational ordering in the hexagonal phase is a much weaker effect than in the lamellae.   we predict the parallel orientation to be stable at low and the perpendicular orientation at high shear rates.   our analysis reproduces the experimental results by tepe _   et al. _    and explains the difficulties in experimental observation of the different orientations in the hexagonal phase.
we discuss the extended nambu - jona - lasinio model as a low energy expansion, all two - point functions and an example of a three - point function to all orders in momenta and quark masses.   the model is treated at leading level in @xmath0 but otherwise exact. some comments about   the qcd flavour anomaly and vector meson dominance in this class of models is made.   nordita-94/43 n, p    * 2 and 3-point functions in the enjl - model.   * +   + @xmath1 nordita, blegdamsvej 17, + dk-2100 copenhagen , denmark + @xmath2niels bohr institute, blegdamsvej 17, + dk-2100 copenhagen , denmark    august 1994
this is the first paper in a series where we study the influence of turbulent diffusion and advective transport on the chemical evolution of protoplanetary disks, using a 2d flared disk model and a 2d mixing gas - grain chemical code with surface reactions. a first interesting result concerns the abundance of gas - phase co in the outer regions of protoplanetary disks.   in this letter we argue that the gas - phase co concentration in the disk regions, where the temperature is lower than @xmath0k, can be significantly enhanced due to the combined effect of vertical and radial mixing.   this finding has a potential implication for the current observational data on the dm  tau disk chemistry.
we have analysed publicly available macho observations of 6833 variable stars in the large magellanic cloud, classified as eclipsing binaries. after finding that a significant fraction of the sample was misclassified, we redetermined periods and variability class for all stars, producing a clean sample of 3031 eclipsing binaries.   we have investigated their distribution in the period - color - luminosity space, which was used, for example, to assign a foreground probability to every object and establish new period - luminosity relations to selected types of eclipsing stars.   we found that the orbital period distribution of lmc binaries is very similar to those of the smc and the milky way.   we have also determined the rate of period change for every star using the o   c method, discovering about 40 eclipsing binaries with apsidal motion, 45 systems with cyclic period changes and about 80 stars with parabolic o  c diagrams. in a few objects we discovered gradual amplitude variation, which can be explained by changes in the orbital inclination caused by a perturbing third body in the system.
habitable zone dust levels are a key unknown that must be understood to ensure the success of future space missions to image earth analogues around nearby stars.   current detection limits are several orders of magnitude above the level of the solar system s zodiacal cloud, so characterisation of the brightness distribution of exo - zodi down to much fainter levels is needed. to this end  , the large binocular telescope interferometer ( lbti ) will detect thermal emission from habitable zone exo - zodi a few times brighter than solar system levels. here   we present a modelling framework for interpreting lbti observations, which yields dust levels from detections and upper limits that are then converted into predictions and upper limits for the scattered light surface brightness.   we apply this model to the hosts survey sample of nearby stars ; assuming a null depth uncertainty of 10@xmath0 the lbti will be sensitive to dust a few times above the solar system level around sun - like stars, and to even lower dust levels for more massive stars.
the anomaly of a discrete symmetry is defined as the jacobian of the path - integral measure.   assuming that the anomaly at low energies is cancelled by the green - schwarz ( gs ) mechanism at a fundamental scale, we investigate possible kac - moody levels for anomalous discrete family symmetries.   as the first example, we consider discrete abelian baryon number and lepton number symmetries in the minimal supersymmetric standard model with the see - saw mechanism, and we find that the ordinary unification of gauge couplings is inconsistent with the gs conditions, indicating the possible existence of further higgs doublets.   we consider various recently proposed supersymmetric models with a non - abelian discrete family symmetry. in a supersymmetric example with @xmath0 family symmetry,   the gs conditions are such that the gauge coupling unification appears close to the planck scale.    kanazawa-06 - 18 + december, 2006    * anomalies of discrete symmetries and + gauge coupling unification *    takeshi araki + _   institute for theoretical physics, kanazawa university, kanazawa 920 - 1192, japan _
we investigate the dynamics of a single phonon ( oscillator ) mode linearly coupled to an electronic few  level system in contact with external particle reservoirs ( leads ). a stationary electronic current through the system generates non  trivial dynamical behaviour of the oscillator.   using feynman   vernon influence functional theory, we derive a langevin equation for the oscillator trajectory that is non  perturbative in the system  leads coupling and from which we extract effective oscillator potentials and friction coefficients.   for the two simplest cases of a single and two coupled electronic levels, we discuss various regimes of the oscillator dynamics.
we present the first experimental evidence for the existence of strongly localized photonic modes due to random two dimensional fluctuations in the dielectric constant. in one direction,   the modes are trapped by ordered bragg reflecting mirrors of a planar, one wavelength long, microcavity. in the cavity plane, they are localized by disorder, which is due to randomness in the position, composition and sizes of quantum dots located in the anti - node of the cavity.   we extend the theory of disorder induced strong localization of electron states to optical modes and obtain quantitative agreement with the main experimental observations.   ,   ,
we report on @xmath0-@xmath1 observations of g32.45 + 0.1 and g38.55 + 0.0. these were discovered as diffuse hard x - ray sources with the @xmath2 galactic plane survey, but the limited spatial resolution of @xmath2 could not conclude whether these are truly diffuse or a group of unresolved point - sources.   @xmath0-@xmath1, with higher spatial resolution than @xmath2, confirmed that g32.45 + 0.1 has a diffuse shell - like structure with a radius of @xmath3.   the spectrum shows featureless continuum, hence can be fitted with a power - law model of @xmath4 with an absorption of @xmath5. from this @xmath6 value  , we estimate the distance to g32.45 + 0.1 to be @xmath7  kpc, then the luminosity ( in the 0.510.0  kev band ) and radius of the shell are @xmath8  ergs  s@xmath9 and @xmath1020  pc, respectively.   the radio complex sources in the nrao / vla sky survey ( nvss ; 1.4  ghz ) are globally associated to the x - ray shell of g32.45 + 0.1.   therefore g32.45 + 0.1 is likely to be a synchrotron dominant shell - like snr.   no significant diffuse structure was found in the @xmath0-@xmath1 image of another @xmath2 diffuse source g38.55 + 0.0.   the upper limit of the observed flux ( 0.510.0  kev ) is estimated to be @xmath11  ergs  @xmath12  s@xmath9 being consistent with the @x
magnetic frustration, which is well - defined in insulating systems with localized magnetic moments, yields exotic ground states like spin ices, spin glasses, or spin liquids. in metals   magnetic frustration is less well defined because of the incipient delocalization of magnetic moments by the interaction with conduction electrons, viz.,   the kondo effect.   hence, the kondo effect and magnetic frustration are antithetic phenomena. here   we present experimental data of electrical resistivity, magnetization, specific heat and neutron diffraction on cepdal, which is one of the rare examples of a geometrically frustrated kondo lattice, demonstrating that the combination of kondo effect and magnetic frustration leads to an unusual ground state.
two recently developed theoretical approaches are applied to the shastry - sutherland lattice, varying the ratio @xmath0 between the couplings on the square lattice and on the oblique bonds. a self - consistent perturbation, starting from either ising or plaquette bond singlets, supports the existence of an intermediate phase between the dimer phase and the ising phase.   this existence is confirmed by the results of a renormalized excitonic method.   this method, which satisfactorily reproduces the singlet triplet gap in the dimer phase, confirms the existence of a gapped phase in the interval @xmath1
the effect of non - locality in the nn interaction models is examined.   it is shown that this feature can explain differences in predictions made from models evidencing a difference with this respect.   this is done for both static and dynamical observables, taking into account that a non - local term can be transformed away by performing a unitary transformation.   some results for the deuteron form factors, the @xmath0 structure function and the @xmath1 tensor polarization are given as an example.   a few cases where discrepancies can not be explained are also considered.   they point to differences in the models as for the deuteron asymptotic normalizations, @xmath2 and @xmath3, which are not affected by the present analysis.
in @xmath0 photoproduction in ultra - peripheral heavy ion collisions, either ion can be the photon emitter or the target.   the two possibilities are indistinguishable, and they should be able to interfere, reducing @xmath1 production at low transverse momentum, @xmath2, where @xmath3 is the median impact parameter.   the two @xmath0 production points are separated by @xmath4 fm, while the @xmath0 decay before travelling 1 fm.   the two decay points are well separated in space - time, so the decays proceed independently and any interference must involve the final state @xmath5.   this requires a non - local wave function.
the formation and evolution of galactic spiral arms is not yet clearly understood despite many analytic and numerical work. recently, a new idea has been proposed that local density enhancements ( waklets ) arising in the galactic disk connect with each other and make global spiral arms. however, the understanding of this mechanism is not yet sufficient.   we analyze the interaction of wakelets by using @xmath0-body simulations including perturbing point masses, which are heavier than individual @xmath0-body particles and act as the seeds for wakelets.   our simulation facilitates more straightforward interpretation of numerical results than previous work by putting a certain number of perturbers in a well - motivated configuration.   we detected a clear sign of non - linear interaction between wakelets, which make global spiral arms by connecting two adjacent wakelets.   we found that the wave number of the strongest non - linear interaction depends on galactic disk mass and shear rate.   this dependence is consistent with the prediction of swing amplification mechanism and other previous results.   our results provide unification of previous results which seemed not consistent with each other.
in order to describe excitable reaction - diffusion systems, we derive a two - dimensional model with a hopf and a semilocal saddle - node homoclinic bifurcation.   this model gives the theoretical framework for the analysis of the saddle - node homoclinic bifurcation as observed in chemical experiments, and for the concepts of excitability and excitability threshold.   we show that if diffusion drives an extended system across the excitability threshold then, depending on the initial conditions, wave trains, propagating solitary pulses and propagating pulse packets can exist in the same extended system.   the extended model shows chemical turbulence for equal diffusion coefficients and presents all the known types of topologically distinct activity waves observed in chemical experiments. in particular,   the approach presented here enables to design experiments in order to decide between excitable systems with sharp and finite width thresholds.   rui dilo    nonlinear dynamics group, instituto superior tcnico    department of physics, av.   rovisco pais, 1049 - 001 lisbon, portugal    andrs volford    center for complex and nonlinear systems, technical university of budapest    h-1521 budapest, hungary
we obtained @xmath0 and b band images of the m31 nucleus using the high resolution camera of the advanced camera for surveys on board the hubble space telescope ( hst ).   the spatial resolution in the @xmath0-band, @xmath1 fwhm, or 0.1 pc at m31, is sufficient to resolve the outskirts of the compact cluster ( p3 ) of uv - bright stars surrounding the m31 black hole.   the center of the cluster is marked by an extended source that is both brighter and redder than the other point sources within p3 ; it is likely to be a blend of several bright stars.   we hypothesize that it marks the location of the m31 black hole. both stellar photometry and a surface brightness fluctuation analysis,   show that the p3 stellar population is consistent with early - type main sequence stars formed in a @xmath2 myr old starburst population.   evolutionary tracks of post early asymptotic giant - branch stars, associated with late - stage evolution of an old population, also traverse the u and @xmath3 domain occupied by the p3 stars ; but we argue that only a few stars could be accounted for that way.   peagb evolution is very rapid, and there is no progenitor population of red giants associated with p3.   the result that p3 comprises young stars is consistent with inferences from earlier hst observations of the integrated light of the cluster. like the milky way, m31 harbors a black hole closely surrounded by apparently young stars.
in this paper, a new mathematical framework to the analysis of millimeter wave cellular networks is introduced.   its peculiarity lies in considering realistic path - loss and blockage models, which are derived from experimental data recently reported in the literature.   the path - loss model accounts for different distributions for line - of - sight and non - line - of - sight propagation conditions and the blockage model includes an outage state that provides a better representation of the outage possibilities of millimeter wave communications. by modeling the locations of the base stations as points of a poisson point process and by relying upon a noise - limited approximation for typical millimeter wave network deployments,   exact integral expressions for computing the coverage probability and the average rate are obtained. with the aid of monte carlo simulations,   the noise - limited approximation is shown to be sufficiently accurate for typical network densities.   furthermore, it is shown that sufficiently dense millimeter wave cellular networks are capable of outperforming micro wave cellular networks, both in terms of coverage probability and average rate.    tba.
it has often been suggested that an alternative to the standard co/21-cm method for estimating the mass of the interstellar medium ( ism ) in a galaxy might be to estimate the mass of the ism from the continuum dust emission. in this paper  , we investigate the potential of this technique using herschel observations of ten galaxies in the herschel reference survey and in the herschel virgo cluster survey.   we show that the emission detected by herschel is mostly from dust that has a temperature and emissivity index similar to that of dust in the local ism in our galaxy, with the temperature generally increasing towards the centre of each galaxy.   we calibrate the dust method using the co and 21-cm observations to provide an independent estimate of the mass of hydrogen in each galaxy, solving the problem of the uncertain ` x factor'for the molecular gas by minimizing the dispersion in the ratio of the masses estimated using the two methods. with the calibration for the dust method and the estimate of the x - factor produced in this way,   the dispersion in the ratio of the two gas masses is 30%, which gives an upper limit on the fundamental accuracy of the dust method.   the calibration we obtain for the dust method is very similar to an independent herschel measurement for m31 and to the calibration for the milky way from planck measurements.
the scale invariance of natural images suggests an analogy to the statistical mechanics of physical systems at a critical point.   here we examine the distribution of pixels in small image patches and show how to construct the corresponding thermodynamics.   we find evidence for criticality in a diverging specific heat, which corresponds to large fluctuations in how ` surprising'we find individual images, and in the quantitative form of the entropy vs.  energy.   the energy landscape derived from our thermodynamic framework identifies special image configurations that have intrinsic error correcting properties, and neurons which could detect these features have a strong resemblance to the cells found in primary visual cortex.
the bak  sneppen model is an abstract representation of a biological system that evolves according to the darwinian principles of random mutation and selection.   the species in the system are characterized by a numerical fitness value between zero and one.   we show that in the case of five species the steady - state fitness distribution can be obtained as a solution to a linear differential equation of order five with hypergeometric coefficients.   similar representations for the asymptotic fitness distribution in larger systems may help pave the way towards a resolution of the question of whether or not, in the limit of infinitely many species, the fitness is asymptotically uniformly distributed on the interval @xmath0 $ ] with @xmath1.
dark matter ( dm ) is currently searched for with a variety of detection strategies.   accelerator searches are particularly promising, but even if weakly interacting massive particles ( wimps ) are found at the large hadron collider ( lhc ), it will be difficult to prove that they constitute the bulk of the dm in the universe @xmath0.   we show that a significantly better reconstruction of the dm properties can be obtained with a combined analysis of lhc and direct detection ( dd ) data, by making a simple ansatz on the wimp local density @xmath1, i.e., by assuming that the local densiy scales with the cosmological relic abundance, @xmath2 ).   we demonstrate this method in an explicit example in the context of a 24-parameter supersymmetric model, with a neutralino lsp in the stau co - annihilation region.   our results show that future ton - scale dd experiments will allow to break degeneracies in the susy parameter space and achieve a significantly better reconstruction of the neutralino composition and its relic density than with lhc data alone.
within low scale theories traditional see - saw and scalar triplet mechanisms, for neutrino mass suppression, do not work out anymore and for realistic model building some new ideas are needed. in this paper   we suggest mechanism, different from existing ones, which provides natural suppression of the neutrino masses.   the mechanism is realized through extended scalars of @xmath0, @xmath1 or @xmath2 dimensional @xmath3 multiplets.   scenario, with fundamental mass scale @xmath4 in a @xmath5  tev range, requires @xmath0-plets guaranteeing neutrino masses @xmath6  ev. for theories with @xmath7  tev @xmath1-plets   should be involved, while in scenarios with @xmath8  few tev, @xmath2-plets could be efficient.   the considered mechanism could be successfully applied also for supersymmetric theories, building scenarios with various values of low @xmath4.    within considered models   we also address the question of gauge coupling unification  . for low scale unification, existence of compact extra dimensions turns out to be crucial. due to additional scalar multiplets,   some new examples of unification are found for both - non susy and susy cases. within non susy scenarios introduced @xmath3 scalars take advantage and are important for successful unification.   epsf    -2 cm -1.5 cm     (    * naturally light neutrinos and unification + in theories with low scale quantum gravity *    zurab tavartkiladze    _ institute of physics, georgian academy of sciences, 380077 tbilisi, georgia _ +
we consider einstein - maxwell - dilaton ( emd ) lagrangian supplemented by double liouville potentials to enrich our system and investigate the resulting dynamics.   the general solution provides us alternative structures induced on the 3-dimensional domain wall ( dw ) moving in the 4-dimensional bulk.   in particular, the local maximum in the potential suggests a maximum bounce ( or onset for a contraction phase ) of the 3-dimensional friedmann - robertson - walker ( frw ) universe on the dw.   depending on the choice of parameters we plot various cases of physical interest.
for active galactic nuclei ( agns ) we study the role of the mechanism of quasi - linear diffusion ( qld ) in producing the high energy emission in the mev - gev domains strongly connected with the submillimeter / infrared radiation. considering the kinetic equation governing the stationary regime of the qld we investigate the feedback of the diffusion on electrons.   we show that this process leads to the distribution of particles by the pitch angles, implying that the synchrotron mechanism is no longer prevented by energy losses. examining a reasonable interval of physical parameters,   we show that it is possible to produce mev - gev @xmath0-rays, strongly correlated with submillimeter / infrared bands.
we have studied the kinetic roughening of an oil  air interface in a forced imbibition experiment in a horizontal hele  shaw cell with quenched disorder.   different disorder configurations, characterized by their persistence length in the direction of growth, have been explored by varying the average interface velocity @xmath0 and the gap spacing @xmath1. through the analysis of the _ rms _ width as a function of time, we have measured a growth exponent @xmath2 that is almost independent of the experimental parameters.   the analysis of the roughness exponent @xmath3 through the power spectrum have shown different behaviors at short ( @xmath4 ) and long ( @xmath5 ) length scales, separated by a crossover wavenumber @xmath6.   the values of the measured roughness exponents depend on experimental parameters, but at large velocities we obtain @xmath7 independently of the disorder configuration.   the dependence of the crossover wavenumber with the experimental parameters has also been investigated, measuring @xmath8 for the shortest persistence length, in agreement with theoretical predictions.
we construct analytically stationary global configurations for both aligned and logarithmic spiral coplanar magnetohydrodynamic ( mhd ) perturbations in an axisymmetric background mhd disc with a power - law surface mass density @xmath0, a coplanar azimuthal magnetic field @xmath1, a consistent self - gravity and a power - law rotation curve @xmath2 where @xmath3 is the linear azimuthal gas rotation speed.   the barotropic equation of state @xmath4 is adopted for both mhd background equilibrium and coplanar mhd perturbations where @xmath5 is the vertically integrated pressure and @xmath6 is the barotropic index. for a scale - free background mhd equilibrium, a relation exists among @xmath7, @xmath8, @xmath9 and @xmath6 such that only one parameter ( e.g., @xmath8 ) is independent. for a linear axisymmetric stability analysis  , we provide global criteria in various parameter regimes. for nonaxisymmetric aligned and logarithmic spiral cases, two branches of perturbation modes ( i.e., fast and   slow mhd density waves ) can be derived once @xmath8 is specified. to complement the magnetized singular isothermal disc ( msid ) analysis of lou,   we extend the analysis to a wider range of @xmath10. as an example of illustration  , we discuss specifically the @xmath11 case when the background magnetic field is force - free.   angular momentum conservation for coplanar mhd perturbations and other relevant aspects of our approach are discussed.   mhd  ism : magnetic fields  stars : formation  galaxies : kinematics and dynamics  galaxies : spiral  galaxies : structure.
we present a new method to compute wavelength- and phase - dependent limb darkening corrections for classical cepheids.   these corrections are derived from hydrodynamic simulations and radiative transfer modeling with a full set of atomic and molecular opacities.   comparison with hydrostatic models having the same stellar parameters show a larger limb darkening for most phases in our models, and temporal variations related to the hydrodynamics of the stellar pulsation.   we assess the implications of our results with respect to the geometric baade - wesselink method, which uses interferometric measurements of cepheid angular diameters to determine their distances and radii.   the relevance of the hydrodynamic effects predicted by our model on the limb darkening of pulsating cepheids is finally discussed in terms of the predicted capabilities of the vlti.
the structure of the al@xmath0pd@xmath1mn@xmath2 surface has been investigated using high resolution scanning tunnelling microscopy ( stm ). from two large five - fold terraces on the surface in a short decorated fibonacci sequence,   atomically resolved surface images have been obtained.   one of these terraces carries a rare local configuration in a form of a ring.   the location of the corresponding sequence of terminations in the bulk model  of icosahedral _   i_-alpdmn based on the three - dimensional tiling 2f  of an f - phase has been estimated using this ring configuration and the requirement from the leed work of gierer  _ et al. _   that the average atomic density of the terminations is 0.136 atoms per @xmath3.   a termination contains two atomic plane layers separated by a vertical distance of 0.48.   the position of the bulk terminations is fixed within the layers of bergman polytopes in the model : they are @xmath4  in the direction of the bulk from a surface of the most dense bergman layers. from the coding windows of the top planes in terminations in   we conclude that a penrose ( p1 ) tiling is possible on almost all five - fold terraces.   the shortest edge of the tiling p1, is either 4.8 or 7.8.   the experimentally derived tiling of the surface with the ring configuration has an edge - length of @xmath5  and hence matches the minimal edge - length expected from the model.
the dalitz decay @xmath0 has been measured in the @xmath1 reaction with the crystal ball and taps multiphoton spectrometers, together with the photon tagging facility at the mainz microtron mami.   the experimental statistic used in this work is one order of magnitude greater than in any previous measurement of @xmath0.   the value obtained for the slope parameter @xmath2 of the @xmath3 transition form factor, @xmath4  gev@xmath5, is in good agreement with recent measurements conducted in @xmath0 and @xmath6 decays, as well as with recent form - factor calculations.   the uncertainty obtained in the value of @xmath2 is lower compared to results from previous measurements of the @xmath0 decay.
we consider a reformulation of qed in which covariant green functions are used to solve for the electromagnetic field in terms of the fermion fields. it is shown that exact few - fermion eigenstates of the resulting hamiltonian can be obtained in the canonical equal - time formalism for the case where there are no free photons.   these eigenstates lead to two- and three - body dirac - like equations with electromagnetic interactions.   perturbative and some numerical solutions of the two - body equations are presented for positronium and muonium - like systems, for various strengths of the coupling.   16.5 cm = -15 mm = 2 mm = 2 mm
in the framework of supersymmetric grand unified theories, the minimal higgs sector is often extended by introducing multi - dimensional higgs representations in order to obtain realistic models.   however these constructions should remain anomaly - free, which constraints significantly their structure.   we review the necessary conditions for the cancellation of anomalies in general and discuss in detail the different possibilities for susy su(5 ) models.   alternative anomaly free combinations of higgs representations, beyond the usual vector - like choice, are identified, and it is shown that their corresponding @xmath0 functions are not equivalent.   although the unification of gauge couplings is not affected, the introduction of multi - dimensional representations leads to different scenarios for the perturbative validity of the theory up to the planck scale.
we study shadowing and antishadowing corrections to the flavor non - singlet structure function @xmath0 and show that the difference between the one - particle density distributions of @xmath1he and @xmath1h plays an important role at very small @xmath2.   we find that the flavor non - singlet structure function in these mirror nuclei is enhanced at small @xmath2 by nuclear shadowing, which increases the nuclear gottfried integral, integrated from @xmath3 to 1, by @xmath4%.   when integrated from zero, the gottfried integral is divergent for these mirror nuclei.   it seems likely that, as a consequence of charge symmetry breaking, this may also apply to the proton - neutron system.
the quasidistributions corresponding to the diagonal representation of quantum states are discussed within the framework of operator - symbol construction.   the tomographic - probability distribution describing the quantum state in the probability representation of quantum mechanics is reviewed.   the connection of the diagonal and probability representations is discussed.   the superposition rule is considered in terms of the density - operator symbols.   the separability and entanglement properties of multipartite quantum systems are formulated as the properties of the density - operator symbols of the system states.
the absence of a batse line detection during the mission s first six years has led to a statistical analysis of the occurrence of lines in the batse database ; this statistical analysis will still be relevant if lines are detected.   we review our methodology, and present new simulations of line detectability as a function of the line parameters.   we also discuss the calculation of the number of `` trials '' in the batse database, which is necessary for our line detection criteria.
results on steady tev @xmath0-ray point source search using data taken from the tibet hd ( feb.   1997  sep.   1999 ) and tibet iii ( nov.   1999  oct.   2001 ) arrays are presented. from @xmath1 to @xmath2 in declination, significant excesses from the well - known steady source crab nebula and the high state of the flare type source markarian 421 are observed.   because the levels of significance from other positions are not sufficiently high, 90% confidence level upper limits on the flux are set assuming different power law spectra.   to allow crosschecking, two independently developed analyses are used in this work.
x - ray variability of the microquasar xte  j1550 - 564 is studied with time domain techniques for the data from the _   rxte_/pca observation in september 8, 1998.   the 260kev averaged shot is obtained from superposing shots with one millisecond time bin through aligning their peaks. the spectral behavior during the averaged shot exhibits prominent differences from that observed in cyg  x-1. the hardness ratio of ( 1360kev)/(213kev ) or ( 1660kev)/(1316kev ) during a shot is lower or higher than that of steady emission respectively.   the correlation coefficient between intensity and hardness ratio of ( 1360kev)/(213kev ) or ( 1660kev)/(1316kev ) is negative or positive respectively.   these results may indicate that physical processes in the low state of xte  j1550 - 564 are different from those in cyg  x-1.
we address the following question.   take the constrained minimal supersymmetric standard model ( cmssm ) with the two cp violating susy phases different from zero, and neglect the bound coming from the electric dipole moment ( edm ) of the neutron : is it possible to fully account for cp violation in the kaon and b systems using only the susy contributions with a vanishing ckm phase?   we show that the @xmath0 constraint, though cp conserving, forces a negative answer to the above question.   this implies that even in the regions of the cmssm where a cancellation of different contributions to the edm allows for large susy phases, it is not possible to exploit the susy phases to fully account for observable cp violation.   hence to have sizeable susy contributions to cp violation, one needs new flavor structures in the sfermion mass matrices beyond the usual ckm matrix.
we present four large sets of evolutionary tracks for stars with initial chemical compositions @xmath0 $ ], @xmath1 $ ], @xmath2 $ ] and @xmath3 $ ] and enhancement of @xmath4 elements with respect to the solar pattern. the major improvement with respect to previous similar calculations   is that we use consistent opacities   i.e. computed with the same chemical composition as adopted in the stellar models  over the whole relevant range of temperatures. for the same initial chemical compositions   @xmath5 $ ] and otherwise identical input physics we present also new evolutionary sequences with solar - scaled mixtures of abundances. based on these stellar models we calculate the corresponding sets of isochrones both in the johnson - cousins @xmath6 and hst / wfpc2 photometric systems.   furthermore, we derive integrated magnitudes, colours and mass - to - light ratios for ideal single stellar populations with total mass equal to @xmath7.   finally, the major changes in the tracks, isochrones, and integrated magnitudes and colours passing from solar - scaled to mixtures are briefly outlined.   retrieval of the complete data set is possible via the www page ` http://pleiadi.pd.astro.it `.
the @xmath0fold degeneracy of the ground state of a quasi - one dimensional system allows it to support topological excitations such as solitons.   we study the combined effects of coulomb interactions and confinement due to interchain coupling on the statistics and thermodynamics of such defects.   we concentrate on a two - dimensional case with @xmath1 which may correspond to monolayers of doped polyacetylene - type polymers or other charge density waves and to junctions in field effect experiments for equivalent materials. combining analytical and numerical methods,   the theory is developed by a mapping to the @xmath2dimensional ising model with long range @xmath3-spin interactions.   we obtain the phase diagram depending on the ratio of coulomb interaction and interchain coupling with respect to temperature.   the latter exhibits deconfined phases for liquids and wigner crystals of kinks, and confined ones for bikinks.   also we find aggregated phases with either infinite domain walls of kinks or finite rods of bikinks.   roughening effects due to both temperature and coulomb repulsion are observed.   applications may concern the melting of stripes in doped correlated materials.
the probability distribution of the mesoscopic local density of states ( ldos ) for a single - channel disordered quantum wire with chiral symmetry is computed in two different geometries.   an approximate ansatz is proposed to describe the crossover of the probability distributions for the conductance and ldos between the chiral and standard symmetry classes of a single - channel disordered quantum wire.   the accuracy of this ansatz is discussed by comparison with a large - deviation ansatz introduced by h.  schomerus and m.  titov in phys.   rev.   b * 67 *, 100201(r ) ( 2003 ).
standard analytical chemical evolution modelling of galaxies has been assuming the stellar initial mass function ( imf ) to be invariant and fully sampled allowing fractions of massive stars to contribute even in dwarf galaxies with very low star formation rates ( sfrs ).   recent observations show the integrated galactic initial mass function ( igimf ) of stars, i.e. the galaxy - wide imf, to become systematically top - heavy with increasing sfr.   this has been predicted by the igimf theory, which is here used to develop the analytical theory of the chemical evolution of galaxies.   this theory is non - linear and requires the iterative solution of implicit integral equations due to the dependence of the igimf on the metallicity and on the sfr.   it is shown that the mass  metallicity relation of galaxies emerges naturally, although at low masses the theoretical predictions overestimate the observations by 0.30.4 dex.   a good agreement with the observation can be obtained only if gas flows are taken into account. in particular, we are able to reproduce the mass  metallicity relation observed by lee et al.   ( 2006 ) with modest amounts of infall and with an outflow rate which decreases as a function of the galactic mass.   the outflow rates required to fit the data are considerably smaller than required in models with invariant imfs.    stars : abundances  stars : luminosity function, mass function   supernovae : general  galaxies : evolution  galaxies : dwarf  galaxies : star clusters : general
in this paper, we consider combinatorial game rulesets based on data structures normally covered in an undergraduate computer science data structures course : arrays, stacks, queues, priority queues, sets, linked lists, and binary trees.   we describe many rulesets as well as computational and mathematical properties about them.   two of the rulesets, and, are new.   we show polynomial - time solutions to and to on paths.
we provide computationally convenient expressions for all marginal distributions of the polarization cmb power spectrum distribution @xmath0, where @xmath1 denotes the set of ensemble averaged polarization cmb power spectra, and @xmath2 the set of the realization specific polarization cmb power spectra.   this distribution describes the cmb power spectrum posterior for cosmic variance limited data.   the expressions derived here are general, and may be useful in a wide range of applications.   two specific applications are described in this paper.   first, we employ the derived distributions within the cmb gibbs sampling framework, and demonstrate a new conditional cmb power spectrum sampling algorithm that allows for different binning schemes for each power spectrum.   this is useful because most cmb experiments have very different signal - to - noise ratios for temperature and polarization.   second, we provide new blackwell - rao estimators for each of the marginal polarization distributions, which are relevant to power spectrum and likelihood estimation.   because these estimators represent marginals, they are not affected by the exponential behaviour of the corresponding joint expression, but converge quickly.
the results from data taken during the last several years at the relativistic heavy - ion collider ( rhic ) will be reviewed in the paper.   several selected topics that further our understanding of constituent quark scaling, jet quenching and color screening effect of heavy quarkonia in the hot dense medium will be presented.   detector upgrades will further probe the properties of quark gluon plasma.   future measurements with upgraded detectors will be presented.   the discovery perspectives from future measurements will also be discussed.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )
we present @xmath0 and @xmath1-band luminosity functions ( lf ) for a sample of 25 nearby groups of galaxies.   we find that the lfs of the groups with low x - ray luminosity ( @xmath2 erg  s@xmath3 ) are significantly different from those of the x - ray brighter groups, showing a prominent dip around @xmath4.   while both categories show lack of late - type galaxies in their central regions, x - ray dim groups also show a more marked concentration of optical luminosity towards the centre.   a toy simulation shows that in the low velocity dispersion environment, as in the x - ray dim group, dynamical friction would facilitate more rapid merging, thus depleting intermediate - luminosity galaxies to form a few giant central galaxies, resulting in the prominent dip seen in our lfs.   we suggest that x - ray dim ( or low velocity dispersion ) groups are the present sites of rapid dynamical evolution rather than their x - ray bright counterparts, and may be the modern precursors of fossil groups.   we predict that these groups of low velocity dispersion would harbour younger stellar populations than groups or clusters with higher velocity dispersion.       galaxies : luminosity functions  galaxies : evolution  galaxies : structure  galaxies : groups
the breaking stress ( the maximum of the stress - strain curve ) of neutron star crust is important for neutron star physics including pulsar glitches, emission of gravitational waves from static mountains, and flares from star quakes.   we perform many molecular dynamic simulations of the breaking stress at different coupling parameters ( inverse temperatures ) and strain rates.   we describe our results with the zhurkov model of strength.   we apply this model to estimate the breaking stress for timescales @xmath0  s  1 year, which are most important for applications, but much longer than can be directly simulated. at these timescales   the breaking stress depends strongly on the temperature. for coupling parameter @xmath1 matter breaks at very small stress, if it is applied for a few years.   this viscoelastic creep can limit the lifetime of mountains on neutron stars.   we also suggest an alternative model of timescale - independent breaking stress, which can be used to estimate an upper limit on the breaking stress.       equation of state  stars : neutron  stars : interiors.
cross sections for proton inelastic collision with different nuclei are described within the glauber and multiple scattering approximations.   a significant difference between approximate `` glauber '' formula and exact calculations with a geometrical scaling assumption for very high - energy cross section is shown.   experimental values of proton  proton cross sections obtained using extensive air shower data are based on the relationship of proton  proton and respective proton  air absorption cross sections. according to obtained results values reported by the akeno and   fly s eye experimental groups are about 10% overestimated.   the proper energy dependence of absorption cross section for collisions with air nuclei is of a great importance for studies of high energy cosmic rays using the monte carlo technique.
in light of the recent discovery by the atlas and cms experiments at the large hadron collider ( lhc ) of a higgs - like particle with a narrow mass range of 125 - 126 gev, we perform an updated analysis on one of the popular scalar dark matter models, the inert higgs doublet model ( ihdm ).   we take into account in our likelihood analysis of various experimental constraints, including recent relic density measurement, dark matter direct and indirect detection constraints as well as the latest collider constraints on the invisible decay width of the higgs boson and monojet search at the lhc.   it is shown that if the invisible decay of the standard model higgs boson is open, lhc as well as direct detection experiments like lux and xenon100 could put stringent limits on the higgs boson couplings to dark matter.   we find that the most favoured parameter space for ihdm corresponds to dark matter with a mass less than 100 gev or so.   in particular, the best - fit points are at the dark matter mass around 70 gev where the invisible higgs decay to dark matter is closed.   scalar dark matter in the higher mass range of 0.5 - 4 tev is also explored in our study. projected sensitivities for the future experiments of monojet at lhc-14, xenon1 t and ams-02 one year antiproton flux   are shown to put further constraints on the existing parameter space of ihdm.
we present a new determination of the mass content of the sculptor dwarf spheroidal galaxy, based on a novel approach which takes into account the two distinct stellar populations present in this galaxy.   this method helps to partially break the well - known mass - anisotropy degeneracy present in the modelling of pressure - supported stellar systems.
in this paper, we model dwarf galaxies as a two  component system of gravitationally coupled stars and atomic hydrogen gas in the external force field of a pseudo  isothermal dark matter halo, and numerically obtain the radial distribution of vertical scale heights.   this is done for a group of four dwarf galaxies ( ddo154, hoii, ic2574 and ngc2366 ) for which most necessary input parameters are available from observations.   the formulation of the equations takes into account the rising rotation curves generally observed in dwarf galaxies.   the inclusion of self  gravity of the gas into the model at par with that of the stars results in scale heights that are smaller than what was obtained by previous authors.   this is important as the gas scale height is often used for deriving other physical quantities. the inclusion of gas self   gravity is particularly relevant in the case of dwarf galaxies where the gas can not be considered a minor perturbation to the mass distribution of the stars.   we find that three out of four galaxies studied show a flaring of their disks with increasing radius, by a factor of a few within several disk scale lengths.   the fourth galaxy has a thick disk throughout.   this arises as a result of the gas velocity dispersion remaining constant or decreasing only slightly while the disk mass distribution declines exponentially as a function of radius.   galaxies : kinematics and dynamics  galaxies : structure  galaxies : dwarf  galaxies : individual : hoii, ic2574, ngc2366, ddo154  galaxies : ism
ultrafast laser - induced demagnetization of gd(0001 ) has been investigated by magneto - induced optical second harmonic generation and the magneto - optical kerr effect which facilitate a comparison of surface and bulk dynamics.   we observe pronounced differences in the transient changes of the surface and bulk sensitive magneto - optical signals which we attribute to transfer of optically excited, spin - polarized carriers between surface and bulk states of the gd(0001 ) film.   a fluence dependent analysis of the bulk magnetization dynamics results in a weak variation of the demagnetization time constant, which starts at about 700  fs and increases by 10% within a fluence variation up to 1  mj/@xmath0.   we compare these results with fluence dependent changes in the transient energy density calculated by the two temperature model.   the determined characteristic times of excess energy transfer from the electron system to the lattice, which is mediated by e - ph scattering, range from 0.2 - 0.6  ps.   such a more pronounced fluence dependent change in the characteristic time compared to the observed rather weakly varying demagnetization times suggests a more advanced description of the optically excited state than by the two - temperature model.
nonlinear oscillators can mutually synchronize when they are driven by common external impulses.   two important scenarios are ( i ) synchronization resulting from phase locking of each oscillator to regular periodic impulses and ( ii ) noise - induced synchronization caused by poisson random impulses, but their difference has not been fully quantified. here   we analyze a pair of uncoupled oscillators subject to common random impulses with gamma - distributed intervals, which can be smoothly interpolated between regular periodic and random poisson impulses.   their dynamics are characterized by phase distributions, frequency detuning, lyapunov exponents, and information - theoretic measures, which clearly reveal the differences between the two synchronization scenarios.
in the present paper, we study the poincar map associated to a periodic perturbation, both in space and time, of a linear hamiltonian system.   the dynamical system embodies the essential physics of stellar pulsations and provides a global and qualitative explanation of the chaotic oscillations observed in some stars.   we show that this map is an area preserving one with an oscillating rotation number function.   the nonmonotonic property of the rotation number function induced by the triplication of the elliptic fixed point is superposed on the nonmonotonic character due to the oscillating perturbation.   this superposition leads to the co - manifestation of generic phenomena such as reconnection and meandering, with the nongeneric scenario of creation of vortices.   the nonmonotonic property due to the triplication bifurcation is shown to be different from that exhibited by the cubic hnon map, which can be considered as the prototype of area preserving maps which undergo a triplication followed by the twistless bifurcation.   our study exploits the reversibility property of the initial system, which induces the time - reversal symmetry of the poincar map.   ,   ,    &    stellar oscillations, low - dimensional chaos, nontwist maps
correctly interpreting observations of sources such as type ia supernovae ( sne ia ) require knowledge of the power spectrum of matter on au scales   which is very hard to model accurately. because under - dense regions account for much of the volume of the universe, light from a typical source probes a mean density significantly below the cosmic mean.   the relative sparsity of sources implies that there could be a significant bias when inferring distances of sne ia, and consequently a bias in cosmological parameter estimation.   while the weak lensing approximation should in principle give the correct prediction for this, linear perturbation theory predicts an effectively infinite variance in the convergence for ultra - narrow beams.   we attempt to quantify the effect typically under - dense lines of sight might have in parameter estimation by considering three alternative methods for estimating distances, in addition to the usual weak lensing approximation.   we find in each case this not only increases the errors in the inferred density parameters, but also introduces a bias in the posterior value.    0.5 cm
we present a description of the behavior of a superfluid gas of fermions in the presence of a feshbach resonance over the complete range of magnetic field detunings. starting from a resonance hamiltonian, we exploit a functional method to describe the continuous behavior from bardeen - cooper - schrieffer to bose - einstein condensation type superfluidity.   our results show an ability for a resonance system to exhibit a high critical temperature comparable to the fermi temperature.   the results are derived in a manner that is shown to be consistent with the underlying microscopic scattering physics.
a system of electrons in the two - dimensional honeycomb lattice with coulomb interactions is described by a renormalizable quantum field theory similar but not equal to qed@xmath0.   renormalization group techniques are used to investigate the infrared behavior of the system that flows to a fixed point with non - fermi liquid characteristics.   there are anomalous dimensions in the fermionic observables, no quasiparticle pole, and anomalous screening of the coulomb interaction.   these results are robust as the fermi level is not changed by the interaction.   the system resembles in the infrared the one - dimensional luttinger liquid.   = = = = = = = = = = = = = = = = = =    -1 true cm    21 true cm    october 1993     +   + ( a renormalization group approach )     _ instituto de estructura de la materia, csic _ + _ serrano 123, 28006 madrid, spain   _ +   + _ cantoblanco, 28049 madrid, spain. _ +   + _ avda. mediterrneo s / n, 28913 legans ( madrid ), spain.
we investigate single sneutrino production in the context of r - parity - violating supersymmetry at future @xmath0 linear colliders. the sneutrino is produced in association with fermion pairs and it is shown   that its decays into two further fermions will lead to a clean signal.   we also discuss possible standard model backgrounds and the effects of beam polarisation.   = -6pt = -1.2 in = 6.4 in = 9.0 in = 0.75 in         2 q^2    //   10_1 ^ 0 1p_1^+ 1m_1 ^ - 1pm_1^    cern - th/2001 - 036 + ippp/01/62 + dcpt/01/24 + december 2001 + revised   +    * a study of single sneutrino production in association + with fermion pairs at polarised photon colliders * + * dilip kumar ghosh@xmath1 and stefano moretti@xmath2 * + _ @xmath3 department of physics, national taiwan university + taipei, taiwan 10617, republic of china _ + _   @xmath4 cern theory division, ch-1211 geneva 23, switzerland + and + institute for particle physics phenomenology, university of durham, durham dh1 3le, uk _ +    1 true cm    pacs nos. : 12.60.jv, 13.10.+q, 14.80.ly
we investigate two chemical abundance calibrations for the narrow - line - region ( nlr ) of active galaxies in terms of three easily observable optical emission - line ratios, namely, @xmath04959,5007/h@xmath1, @xmath06548,84/h@xmath2 and @xmath3@xmath04959,5007. the calibrations are obtained from a grid of models on the assumption that the main process responsible for the production of these lines is photoionization by a `` typical '' active galactic nucleus continuum.   the chemical elements vary their abundance together with oxygen, except nitrogen, which is assumed to be a product of secondary nucleosynthesis.   the calibrations are calculated for the range @xmath4, and tested using nlr data for a sample of seyfert s and liner s having hii regions in the vicinity of the nucleus.   the gaseous abundances of these hii regions have been determined in previous works, and the nlr abundances are obtained on the assumption that they can be extrapolated from those of the hii regions. the calibrations work very well for the seyfert s, giving abundance values which agree with those obtained from the hii regions, and can thus be used for quick estimates of the chemical abundances of the nlr s. for the liner s, the calibrations give lower values than those derived from the corresponding hii regions, suggesting that the assumptions of the models do not apply for them, and that there are different physical processes at work in the nlr of the liner s.
the balloon - borne submillimeter instrument pronaos has observed one square degree areas towards the orion and m17 molecular clouds.   the 2 - 3.5 resolution maps obtained in four wide wavelength bands between 200 @xmath0 and 600 @xmath0, exhibit the dust distribution in these regions.   we analyze the temperature and spectral index of the dust, and we show the anticorrelation between these two parameters.   we derive estimations of the ism column densities and masses in these regions.
we draw attention to a clear dichotomy between small - world networks exhibiting exponential neighborhood growth, and fractal - like networks where neighborhoods grow according to a power law.   this distinction is observed in a number of real - world networks, and is related to the degree correlations and geographical constraints.   we conclude by pointing out that the status of human social networks in this dichotomy is far from clear.
galaxy mergers are important events that can determine the fate of a galaxy by changing its morphology, star - formation activity and mass growth.   merger systems have commonly been identified from their disturbed morphologies, and we now can employ integral field spectroscopy to detect and analyze the impact of mergers on stellar kinematics as well. we visually classified galaxy morphology using deep images ( @xmath0 ) taken by the blanco 4-m telescope at the cerro tololo inter - american observatory. in this paper   we investigate 63 bright ( @xmath1 ) spectroscopically - selected galaxies in abell 119 ; of which 53 are early type and 20 galaxies show a disturbed morphology by visual inspection. a misalignment between the major axes in the photometric image and   the kinematic map is conspicuous in morphologically - disturbed galaxies.   our sample is dominated by early - type galaxies, yet it shows a surprisingly tight tully - fisher relation except for the morphologically - disturbed galaxies which show large deviations.   three out of the eight slow rotators in our sample are morphology disturbed.   the visually - selected morphologically - disturbed galaxies are generally more asymmetric, visually as well as kinematically.   our findings suggest that galaxy interactions, including mergers and perhaps fly - bys, play an important role in determining the orientation and magnitude of galaxy s angular momentum.
the study of the very young open cluster ngc 6231 clearly shows the presence of a mass segregation for the most massive stars.   these observations, combined with those concerning other young objects and very recent numerical simulations, strongly support the hypothesis of an initial origin for the mass segregation of the most massive stars.   these results led to the conclusion that massive stars form near the center of clusters.   they are strong constraints for scenarii of star and stellar cluster formation.   escribir aqu el resumen en espaol ( generalmente es 10% ms largo que en ingls ).   ...  ...   ...   ...
recent observations of sunspot s umbra suggested that it may be finely structured at a sub - arcsecond scale representing a mix of hot and cool plasma elements. in this study   we report the first detailed observations of the umbral spikes, which are cool jet - like structures seen in the chromosphere of an umbra.   the spikes are cone - shaped features with a typical height of 0.5 - 1.0  mm and a width of about 0.1  mm.   their life time ranges from 2 to 3  min and they tend to re - appear at the same location.   the spikes are not associated with photospheric umbral dots and they rather tend to occur above darkest parts of the umbra, where magnetic fields are strongest.   the spikes exhibit up and down oscillatory motions and their spectral evolution suggests that they might be driven by upward propagating shocks generated by photospheric oscillations.   it is worth noting that triggering of the running penumbral waves seems to occur during the interval when the spikes reach their maximum height.
the structure and strain of ultrathin coo films grown on a pt(001 ) substrate and on a ferromagnetic ptfe pseudomorphic layer on pt(001 ) have been determined with @xmath0 and real time surface x - ray diffraction.   the films grow epitaxially on both surfaces with an in - plane hexagonal pattern that yields a pseudo - cubic coo(111 ) surface.   a refined x - ray diffraction analysis reveals a slight monoclinic distortion at rt induced by the anisotropic stress at the interface. the tetragonal contribution to the distortion results in a ratio @xmath1,   opposite to that found in the low temperature bulk coo phase.   this distortion leads to a stable co@xmath2 spin configuration within the plane of the film.
we briefly recall the physical background of the transport of angular momentum and the mixing of chemicals inside stellar radiation zones and its importance for stellar evolution.   then, we describe its present modeling, its successes and its weaknesses.   next, we introduce the new theoretical developments that allow us to treat in a self - consistent way the effect of the coriolis force on the low - frequencies internal waves and its consequences for the transport processes.   this research is aimed at improving the modeling of stellar interiors in the perspective of future astero and helioseismology missions such as corot and golf - ng.
we present vlt fors1 spectroscopy that temporally resolves the second caustic crossing of the bulge k giant source of microlensing event, the first time this has been accomplished for several phases of a caustic transit.   the @xmath01   h@xmath1 equivalent width of the source star increases slightly as the center of the star egresses the caustic and then plummets by 30% during the final limb crossing.   these changes are not seen in contemporaneous spectra of control stars in the fors1 slit, but are qualitatively consistent with expectations from stellar atmosphere models as the caustic differentially magnifies different portions of the stellar face of the target.   observations such as these in a variety of stellar lines are equivalent to atmospheric tomography and are expected to provide a direct test of stellar models.    #   1#1  _get ref _    -0.1 cm
the structural and nucleosynthetic evolution of 3, 4, 5, 6 and @xmath0 stars with two metallicities ( @xmath1 and 0.02 ) has been computed in detail, from the early pre - main sequence phase up to the thermally pulsing ( tp ) agb phase or the onset of off - center carbon burning. typically 10 to 20 thermal pulses have been followed for each tp - agb object.   this homogeneous and quite large set of models allows us to present an overview of the thermal pulse properties as well as of the nucleosynthesis accompanying the tp - agb phase of intermediate - mass stars.   more specifically, after a brief description of the previous evolutionary stages, predictions are given for the isotopic ratios involving c,   n, o, ne, mg, al and si. also the surface abundances of @xmath2, @xmath3 and @xmath4 are reported. as the asymptotic phase of the thermal pulses has been reached for each star  , we also indicate how these abundances will probably evolve until the stars completely loose their envelope, by including the evolution of the nucleosynthesis itself.   this article, in its paper form, has been shortened at a level of roughly 60 % as required by directives coming from the a&a editors.   the complete article ( 50 pages containing 37 figures ) is only available in electronic form.   # 1    2.75truecm
* abstract * +    we derive a local - time path - integral representation for a generic one - dimensional time - independent system.   in particular, we show how to rephrase the matrix elements of the bloch density matrix as a path integral over @xmath0-dependent local - time profiles.   the latter quantify the time that the sample paths @xmath1 in the feynman path integral spend in the vicinity of an arbitrary point @xmath0.   generalization of the local - time representation that includes arbitrary functionals of the local time is also provided.   we argue that the results obtained represent a powerful alternative to the traditional feynman  kac formula, particularly in the high and low temperature regimes.   to illustrate this point, we apply our local - time representation to analyze the asymptotic behavior of the bloch density matrix at low temperatures.   further salient issues, such as connections with the sturm  liouville theory and the rayleigh   ritz variational principle are also discussed.
optical photometric and spectroscopic data are presented that show an association of an ultraluminous x - ray source in ngc  7331  with a young star cluster of mass @xmath0  m@xmath1  and age @xmath2 myr. if the ulx is part of the bright stellar cluster, then the mass of the progenitor of the compact accretor must have been @xmath340 - 50  m@xmath1 in order to already have evolved through the supernova stage to a compact object.   the companion star is also likely an evolved massive star.   the emission line spectrum of the nebula surrounding the cluster can be interpreted as a result of photoionization by the cluster ob stars with an additional source of shock excitation producing strong ,   and n  ii  lines.   this additional source appears to be as much as five times more powerful than the supernovae and stellar winds in the cluster can provide.   additional mechanical energy input associated with the ulx itself can help explain the residual shock excited line luminosities of the emission region.
dissipation using a finite environment coupled to a single harmonic oscillator have been studied quite extensively.   we extend the study by looking at the dynamics of the dissipation when we introduce a second bath of @xmath0 identical quartic systems different from the 1st bath.   we look at the energy flow into the environment as a function of the chaotic parameters of the bath and also try to develop a linear response theory to describe the system.   the energy flow is always more to the more chaotic system irrespective of the initial energy of the baths.
in the present paper we analyze the spectrum of quasinormal modes for massive scalar and dirac fields, allowing for both tardyonic ( @xmath0 ) and tachyonic ( @xmath1 ) masses, in the expanding and rotating cosmological background.   the spectrum found shows a number of peculiar features, which are absent in the minkowski space - time.   a hypothetical particle that moves faster than light, _ a tachyon _, is known to be classically unstable in the minkowski space - time.   this instability has its analog at the quantum level : small vacuum fluctuations of the field lead to the unbounded growth of the amplitude, so that the appearance of the real tachyons in the spectrum means that there is catastrophic instability in the theory.   it has been conjectured a long time ago that possibly the lightest particles with nonzero mass, the neutrino, may be a tachyon.   here we shall show that in the rotating and expanding universe tachyons are stable if their mass is less than some constant, which is related to the universe s rotation and expansion scales.   the current upper bound on the rotation scale gives us a very small upper bound on the tachyon s mass which is many orders less than the mass of the electron.   this might explain why only very light particles have the chance of becoming tachyons.   it is shown that the spectrum of the `` normal '' ( @xmath0 ) dirac field has a discontinuity as a function of the z - component of the wave vector @xmath2 at @xmath3.
we consider various incommensurate ( ic ) order parameters for electrons on a square lattice which reduce to @xmath0-density wave ( ddw ) order when the ordering wavevector @xmath1.   we describe the associated charge and current distributions and their experimental signatures.   such orders can arise at the mean - field level in extended hubbard models.   we compare the phase diagrams of these models with experiments in the underdoped cuprates, where ( 1 ) ddw order is a possible explanation of the pseudogap, and ( 2 ) there are experimental indications of incommensurability.   we find various types of ic ddw and discuss their possible relevance to the physics of the cuprates.   our main finding is that ic ddw order is generally accompanied by superconducting order, but the magnitude of the ic wavevector can be small.   a comparison with the analogous af - icsdw transition is given.
financial markets are highly correlated systems that reveal both the inter - market dependencies and the correlations among their different components.   standard analyzing techniques include correlation coefficients for pairs of signals and correlation matrices for rich multivariate data. in the latter case one   constructs a real symmetric matrix with real non - negative eigenvalues describing the correlation structure of the data.   however, if one performs a correlation - function - like analysis of multivariate data, when a stress is put on investigation of delayed dependencies among different types of signals, one can calculate an asymmetric correlation matrix with complex eigenspectrum. from the random matrix theory point of view   this kind of matrices is closely related to ginibre orthogonal ensemble ( ginoe ).   we present an example of practical application of such matrices in correlation analyses of empirical data. by introducing the time lag, we are able to identify temporal structure of the inter - market correlations.   our results show that the american and german stock markets evolve almost simultaneously without a significant time lag so that it is hard to find imprints of information transfer between these markets.   there is only an extremely subtle indication that the german market advances the american one by a few seconds.
i present recent and forthcoming works to model the califa h  ii region using photoionization models.   the first results are obtained with ad - hoc models ( combining parameter determination by model fitting and strong line methods ) while the next ones will use a genetic algorithm to fit the observations in a multi - dimensional space  .    1.0 cm
the question of the origin of hadron masses is one major issue in the understanding of the strong interaction.   the challenge is addressed by searching for indications of in - medium modifications of hadron properties and studying hadrons in nuclei.   the quest driving in - medium studies is to understand the origin of hadron masses in the context of spontaneous chiral symmetry breaking.   the experimental status of the modification of hadron properties in the nuclear medium is discussed including experiments using hadron, heavy - ion, and photon beams.   particular emphasis is put on the production of light mesons from nuclei.   a number of experimental programs is underway to provide a detailed comparison of properties of free hadrons and hadrons embedded in nuclei.   the existing experimental efforts are discussed and possibilities are introduced for the new wasa - at - cosy facility, initially focussed on investigations of symmetries and symmetry breaking, to contribute to the field.   meson production, photoproduction reactions 01.30.cc, 25.40.-h, 13.60.le, 25.20.lj
we propose and evaluate the graphene layer ( gl ) infrared photodetectors ( glips ) based on the van der waals ( vdw ) heterostructures with the radiation absorbing gls.   the operation of the glips is associated with the electron photoexcitation from the gl valence band to the continuum states above the inter - gl barriers ( either via tunneling or direct transitions to the continuum states ). using the developed device model  , we calculate the photodetector characteristics as functions of the gl - vdw heterostructure parameters.   we show that due to a relatively large efficiency of the electron photoexcitation and low capture efficiency of the electrons propagating over the barriers in the inter - gl layers, glips should exhibit the elevated photoelectric gain and detector responsivity as well as relatively high detectivity.   the possibility of high - speed operation, high conductivity, transparency of the glip contact layers, and the sensitivity to normally incident ir radiation provides additional potential advantages in comparison with other ir photodetectors.   in particular, the proposed glips can compete with unitravelling - carrier photodetectors.   + * keywords * : graphene, van der waals heterostructure, infrared photodetector +
during lhc run 1, the lhcb experiment recorded around @xmath0 collision events.   this paper describes event index  an event search system.   its primary function is to quickly select subsets of events from a combination of conditions, such as the estimated decay channel or number of hits in a subdetector.   event index is essentially apache lucene @xcite optimized for read - only indexes distributed over independent shards on independent nodes.
sparse decomposition of ground penetration radar ( gpr ) signals facilitates the use of compressed sensing techniques for faster data acquisition and enhanced feature extraction for target classification. in this paper, we investigate use of an online dictionary learning ( odl ) technique in the context of gpr to bring down the learning time as well as improve identification of abandoned anti - personnel landmines. our experimental results using real data from an l - band gpr for pmn / pma2, era and t72 mines show that odl reduces learning time by 94% and increases clutter detection by 10% over the classical k - svd algorithm.   moreover, our methods could be helpful in cognitive operation of the gpr where the system adapts the range sampling based on the learned dictionary.   ground penetration radar, online dictionary learning, ksvd, compressed sensing, cognitive radar
we present a detailed treatment of the nonequilibrium green s function method for thermal transport due to atomic vibrations in nanostructures. some of the key equations, such as self - energy and conductance with nonlinear effect, are derived.   a self - consistent mean - field theory is proposed.   computational procedures are discussed.   the method is applied to a number of systems including one - dimensional chains, a benzene ring junction, and carbon nanotubes.   mean - field calculations of the fermi - pasta - ulam model are compared with classical molecular dynamics simulations.   we find that nonlinearity suppresses thermal transport even at moderately high temperatures.
we present an empirical method for converting single - point near - infrared @xmath0, @xmath1, and @xmath2 measurements of fundamental - mode cepheids to mean magnitudes, using complete light curves in @xmath3 or @xmath4 bands.   the algorithm is based on the template light curves in the near - infrared bandpasses.   the mean uncertainty of the method is estimated to about 0.03 mag, which is smaller than the uncertainties obtained in other approaches to the problem in the literature.
adhesion - dependent cells actively sense the mechanical properties of their environment through mechanotransductory processes at focal adhesions, which are integrin - based contacts connecting the extracellular matrix to the cytoskeleton. here   we present first steps towards a quantitative understanding of focal adhesions as mechanosensors.   it has been shown experimentally that high levels of force are related to growth of and signaling at focal adhesions.   in particular, activation of the small gtpase rho through focal adhesions leads to the formation of stress fibers. here   we discuss one way in which force might regulate the internal state of focal adhesions, namely by modulating the internal rupture dynamics of focal adhesions.   a simple two - spring model shows that the stiffer the environment, the more efficient cellular force is built up at focal adhesions by molecular motors interacting with the actin filaments.
in the context of a gravity s rainbow, the asymptotic quasinormal modes of the scalar perturbation in the quantum modified schwarzschild black holes are investigated. by using the monodromy method, we calculated and obtained the asymptotic quasinormal frequencies, which are dominated not only by the mass parameter of the spacetime, but also by the energy functions from the modified dispersion relations.   however, the real parts of the asymptotic quasinormal modes is still @xmath0, which is consistent with hod s conjecture.   in addition, for the quantum corrected black hole, the area spacing is calculated and the result is independent of the energy functions, in spite of the area itself is energy dependence. and that, by relating the area spectrum to loop quantum gravity, the barbero - immirzi parameter is given and it remains the same as from the usual black hole.
the _ james webb space telescope _ ( _ jwst _ ), as the largest space - based astronomical observatory with near- and mid - infrared instrumentation, will elucidate many mysterious aspects of comets. we summarize four cometary science themes especially suited for this telescope and its instrumentation : the drivers of cometary activity, comet nucleus heterogeneity, water ice in comae and on surfaces, and activity in faint comets and main - belt asteroids. with _ jwst _, we can expect the most distant detections of gas, especially co@xmath0, in what we now consider to be only moderately bright comets. for nearby comets,   coma dust properties can be simultaneously studied with their driving gases, measured simultaneously with the same instrument or contemporaneously with another.   studies of water ice and gas in the distant solar system will help us test our understanding of cometary interiors and coma evolution.   the question of cometary activity in main - belt comets will be further explored with the possibility of a direct detection of coma gas.   we explore the technical approaches to these science cases and provide simple tools for estimating comet dust and gas brightness. finally, we consider the effects of the observatory s non - sidereal tracking limits, and provide a list of potential comet targets during the first 5 years of the mission.
we extend the scalar sector of the neutrinophilic two higgs doublet model, where small masses of dirac neutrinos are obtained via a small vacuum expectation value @xmath0 of the neutrinophilic @xmath1-doublet scalar field which has a yukawa interaction with only right - handed neutrinos.   a global @xmath2 symmetry is used for the neutrinophilic nature of the second @xmath1-doublet scalar field and also for eliminating majorana mass terms of neutrinos. by virtue of an appropriate assignment of the @xmath2-charges to new particles  , our model has an unbroken @xmath3 symmetry, under which the lightest @xmath3-odd scalar boson can be a dark matter candidate. in our model, @xmath0 is generated by the one - loop diagram to which @xmath3-odd particles contribute.   we briefly discuss a possible signature of our model at the lhc.
the ultraluminous x - ray sources ( ulxs ) were isolated in external galaxies for the last 5 years.   their x - ray luminosities exceed 100 - 10000 times those of brightest milky way black hole binaries and they are extremely variable.   there are two models for the ulxs, the best black hole candidates.   1. they are supercritical accretion disks around a stellar mass black hole like that in ss433, observed close to the disk axes.   2. they are intermediate mass black holes ( of 100 - 10000 solar masses ).   critical observations which may throw light upon the ulxs nature come from observations of nebulae around the ulxs.   we present results of 3d - spectroscopy of nebulae around several ulxs located in galaxies at 3 - 6 mpc distances.   we found that the nebulae to be powered by their central black holes.   the nebulae are shocked and dynamically perturbed probably by jets.   the nebulae are compared with ss433 nebula ( w50 ).
we present a study of selected potential @xmath0doradus stars observed in the geneva photometric system.   eleven stars were monitored at least during the last year of functioning of the 70 cm swiss telescope at la silla, leading to about one thousand photometric measurements and permitting a detailed analysis of these stars.   after the analysis, five stars are thought to be constant stars.   we report three new @xmath1 dor stars.   a spectroscopic campaign has been started at la silla with the new 1m20 swiss telescope, equipped with the spectrograph coralie, of which we show the results for the selected stars.
we have obtained integral field spectroscopy for 23 spiral bulges using integral on the william herschel telescope and spiral on the anglo - australian telescope.   this is the first 2d survey directed solely at the bulges of spiral galaxies.   eleven galaxies of the sample do not have previous measurements of the stellar velocity dispersion ( @xmath0 ).   these data are designed to complement our space telescope imaging spectrograph program for estimating black hole masses in the range @xmath1 using gas kinematics from nucleated disks.   these observations will serve to derive the stellar dynamical bulge properties using the traditional mgb and caii triplets.   we use both cross correlation and maximum penalized likelihood to determine projected @xmath0 in these systems and present radial velocity fields, major axis rotation curves, curves of growth and @xmath0 fields. using the cross correlation to extract the low order 2d stellar dynamics we generally see coherent radial rotation and irregular velocity dispersion fields suggesting that @xmath0 is a non - trivial parameter to estimate.
we consider the neumann laplacian acting on square - integrable functions on a triangle in the hyperbolic plane that has one cusp.   we show that the generic such triangle has no eigenvalues embedded in its continuous spectrum. to prove this result we study the behavior of the real - analytic eigenvalue branches of a degenerating family of triangles.   in particular, we use a careful analysis of spectral projections near the crossings of these eigenvalue branches with the eigenvalue branches of a model operator.
trieste conference proceedings, _ first steps in the origin of life in the universe _, trieste - italy, 18 - 22 sptember 2000 ] at early times   the universe was filled up with an extremely dense and hot gas. due to the expansion it cooled below the binding energies of atoms which led to the formation of the first nuclei. in the physical environment of the post - recombination period of hydrogen  , molecules such as @xmath0, @xmath1 and @xmath2 can be formed.   the proto - object formation, resulting from the growth of linear density fluctuations in the early universe, can have an important impact on the chemical state of the universe.   hence it can be enriched with metals, and thus lead to the formation of the first pre - biotic molecules.   + in this contribution, i will present some scheme for the formation of primordial molecules and discuss the consequence of the formation of first stars on the existence of possible primordial pre - biotic.
we introduce a new achievability scheme, termed _ opportunistic network decoupling ( ond ) _, operating in virtual full - duplex mode. in the scheme,   a novel relay scheduling strategy is utilized in the _   @xmath0 channel with interfering relays _, consisting of @xmath1 source  destination pairs and @xmath2 half - duplex relays in - between them.   a subset of relays using alternate relaying is opportunistically selected in terms of producing the minimum total interference level, thereby resulting in network decoupling. as our main result, it is shown that under a certain relay scaling condition, the ond protocol achieves @xmath1 degrees of freedom even in the presence of interfering links among relays.   numerical evaluation is also shown to validate the performance of the proposed ond.   our protocol basically operates in a fully distributed fashion along with local channel state information, thereby resulting in a relatively easy implementation.   degrees of freedom ( dof ), half - duplex, interference, @xmath3 channel, opportunistic network decoupling ( ond ), relay, virtual full - duplex ( fd ).
we study cosmological defect formation that is induced by brane dynamics after brane inflation.   the cosmological defects are corresponding to the branes that have less than three spacial dimensions in the uncompactified spacetime.   contrary to the previous arguments, production of monopoles and domain walls are not always negligible.   monopoles and domain walls are formed by the branes extended between mother branes.   sit - hep / tm-23    1.5 truecm   .75 truecm    * tomohiro matsuda *   .4 truecm    _ laboratory of physics, saitama institute of technology, _    _ fusaiji, okabe - machi, saitama 369 - 0293, japan _    \1.   truecm addtoresetequationsection 1  . truecm
for a nonsingular real algebraic curve in @xmath0-dimensional projective space or @xmath0-sphere, a new integer - valued characteristic is introduced.   it is invariant under rigid isotopy and multiplied by @xmath1 under mirror reflections. in a sense, it is a vassiliev invariant of degree @xmath2 and a counterpart of a link diagram writhe.
in this paper, we study the anisotropy of cosmic acceleration by dividing the union2 type ia supernova dataset into 12 subsets according to their positions in galactic coordinate system. in each region  , we derive the deceleration parameter @xmath0 as the diagnostic to quantify the anisotropy level in the corresponding direction, and construct @xmath0 anisotropic maps by combining these @xmath0 values.   in addition to the monopole component, we find the significant dipole effect in the @xmath0-maps with the amplitude @xmath1, which deviates from zero at more than 2-@xmath2 level.   the direction of the best - fit dipole is ( @xmath3, @xmath4 ) in galactic system.   interesting enough, we find the direction of this dipole is nearly perpendicular to the cmb kinematic dipole, and the angle between them is @xmath5.   the perpendicular relation is anomalous at the 1-in-10 level.   * keywords.   * cosmic acceleration, anisotropy
the production of @xmath0 mesons in fixed target @xmath1 collisions is considered.   it is shown that non - relativistic qcd predicts @xmath0 states to be produced with sizeable transverse polarization.   the possibility of a measurement of the @xmath0 polarization at the hera-@xmath2 experiment is discussed.   desy 98 - 183 + hep - ph/9811361 + november 1998    * @xmath0 polarization at hera-@xmath2 *    a.  kharchilava@xmath3, t.  lohse@xmath4, a.  somov@xmath4, a.  tkabladze@xmath5    _ @xmath3 institute of physics, georgian academy of sciences, tbilisi _ + _ @xmath4 humboldt - university, berlin, germany _   + _ @xmath5 desy zeuthen, d-15738 zeuthen, germany _ +    : 13.20.gd, 13.88.+e, 13.60.le, 12.38.qk
electronic and atomic structures of the clean, and as and te covered si(211 ) surface are studied using pseudopotential density functional method. the clean surface is found to have @xmath0 and rebonded @xmath1 reconstructions as stable surface structures, but no @xmath2-bonded chain reconstruction.   binding energies of as and te adatoms at a number of symmetry sites on the ideal and @xmath0 reconstructed surfaces have been calculated because of their importance in the epitaxial growth of cdte and other materials on the si(211 ) surface.   the special symmetry sites on these surfaces having the highest binding energies for isolated as and te adatoms are identified. but more significantly, several sites are found to be nearly degenerate in binding energy values.   this has important consequences for epitaxial growth processes.   optimal structures calculated for 0.5 ml of as and te coverage reveal that the as adatoms dimerize on the surface while the te adatoms do not. however, both as and te covered surfaces are found to be metallic in nature.
in early hiv infection, the virus population escapes from multiple @xmath0 cell responses.   the later an escape mutation emerges, the slower it outgrows its competition, i. e. the escape rate is lower.   this pattern could indicate that the strength of the @xmath0 cell responses is waning, or that later viral escape mutants carry a larger fitness cost. in this paper  , we investigate whether the pattern of decreasing escape rate could also be caused by genetic interference among different escape strains. to this end  , we developed a mathematical multi - epitope model of hiv dynamics, which incorporates stochastic effects, recombination and mutation.   we used cumulative linkage disequilibrium measures to quantify the amount of interference.   we found that nearly synchronous, similarly strong immune responses in two - locus systems enhance the generation of genetic interference.   this effect, combined with densely spaced sampling times at the beginning of infection, leads to decreasing successive escape rate estimates, even when there were no selection differences among alleles.   these predictions are supported by experimental data from one hiv - infected patient.   thus, interference could explain why later escapes are slower.   considering escape mutations in isolation, neglecting their genetic linkage, conceals the underlying haplotype dynamics and can affect the estimation of the selective pressure exerted by cd@xmath1 cells. in systems in which multiple escape mutations appear, the occurrence of interference dynamics should be assessed by measuring the linkage between different escape mutations.
slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts.   the interplay between the spontaneous fluid flow, brownian motion, and the elasticity of the body presents a challenging fluid - structure interaction problem. here  , we model this problem by approximating the slender body as an elastic filament that can impose non - equilibrium velocities or stresses at the fluid - structure interface. we derive equations of motion for such an active filament by enforcing momentum conservation in the fluid - structure interaction and assuming slow viscous flow in the fluid.   the fluid - structure interaction is obtained, to any desired degree of accuracy, through the solution of an integral equation.   a simplified form of the equations of motion, that allows for efficient numerical solutions, is obtained by applying the kirkwood - riseman superposition approximation to the integral equation.   we use this form of the equation of motion to study dynamical steady states in free and hinged minimally active filaments.   our model provides the foundation to study collective phenomena in momentum - conserving, brownian, active filament suspensions.
in this paper we propose a new method called nd - tree for fast online update of a pareto archive composed of mutually non - dominated solutions.   nd - tree uses a tree structure in which each node represents a subset of solutions contained in a hypercube defined by its local approximate ideal and nadir points.   a leaf is a subset of solutions organized as a simple list, and an internal node is subset of solutions composed of the union of all its sub - nodes. using heuristic rules we build subsets, either leafs or internal nodes, containing solutions located close in the objective space. using basic properties of local ideal and nadir points   we can efficiently avoid searching many branches in the tree.   nd - tree may be used in any multiobjective metaheuristics e.g. in an multiobjective evolutionary algorithm to update the external archive of potentially efficient solutions.   we experimentally compare nd - tree to simple list, quad - tree, and m - front methods using artificial and realistic benchmarks.   finally we apply nd - tree within two - phase pareto local search for traveling salesperson problems instances with up to 6 objectives.   we show that with this new method substantial reduction of the computational time can be obtained.   multiobjective optimization, pareto archive, quad - tree, pareto local search, many - objective optimization
we present the first unrestricted, three - dimensional relativistic hydrodynamical calculations of the blob of gas associated with the jet producing a gamma - ray burst.   we investigate the deceleration phase of the blob corresponding to the time when afterglow radiation is produced, concentrating on the transition in which the relativistic beaming @xmath0 goes from being less than @xmath1, where @xmath2 is the bulk lorentz factor and @xmath1 is the angular width of the jet, to @xmath3 greater than @xmath1.   we study the time dependent evolution of the physical parameters associated with the jet, both parallel to the direction of motion and perpendicular to it.   we calculate light curves for observers at varying angles with respect to the velocity vector of the blob, assuming optically thin emission that scales with the local pressure.   our main findings are that ( i ) gas ahead of the advancing blob does not accrete onto and merge with the blob material but rather flows around the blob, ( ii ) the decay light curve steepens at a time corresponding roughly to @xmath4 ( in accord with earlier studies ), and ( iii ) the rate of decrease of the forward component of momentum in the blob is well - fit by a simple model in which the gas in front of the blob exerts a drag force on the blob, and the cross sectional area of the blob increases quadratically with laboratory time ( or distance ).    # 1#20.837ex    0.75truein    * to appear in the astrophysical journal *    _ subject headings : _ gamma rays : bursts - hydrodynamics - relativity - shock waves
on microstructured hydrophobic surfaces, geometrical patterns may lead to the appearance of a superhydrophobic state, where gas bubbles at the surface can have a strong impact on the fluid flow along such surfaces.   in particular, they can strongly influence a detected slip at the surface.   we present two - phase lattice boltzmann simulations of a flow over structured surfaces with attached gas bubbles and demonstrate how the detected slip depends on the pattern geometry, the bulk pressure, or the shear rate. since a large slip leads to reduced friction, our results allow to assist in the optimization of microchannel flows for large throughput.
we consider prescriptions that are free from the direct charge - screening effects by quark loops and enable us to clarify the confining nature of a vacuum.   we test two candidates for an order parameter, a polyakov loop ( @xmath0 ) evaluated in zero - triality backgrounds and fermionic determinants ( @xmath1 ) with non - zero triality.   especially, @xmath1 has very small fluctuations in comparison with a polyakov loop in zero - triality sector, and seems to well reflect the characteristic of a vacuum.   such prescriptions could be still usable for the clarification of the confinement property of a vacuum.
we provide a brief review of recent progress in the study of mesons using qcd s dyson - schwinger equations. along the way we touch on aspects of confinement and dynamical chiral symmetry breaking but in the main focus upon : exact results for pseudoscalar mesons, including aspects of the @xmath0-@xmath1 problem ; a realisation that the so - called vacuum condensates are actually an intrinsic, localised property of hadrons ; an essentially nonperturbative procedure for constructing a symmetry - preserving bethe - salpeter kernel, which has enabled a demonstration that dressed - quarks possess momentum - dependent anomalous chromo- and electromagnetic moments that are large at infrared momenta, and resolution of a longstanding problem in understanding the mass - splitting between @xmath2- and @xmath3-mesons such that they are now readily seen to be parity partners in the meson spectrum ; features of electromagnetic form factors connected with charged and neutral pions ; and computation and explanation of valence - quark distribution functions in pseudoscalar mesons.   we argue that in solving qcd, a constructive feedback between theory and extant and forthcoming experiments will enable constraints to be placed on the infrared behaviour of qcd s @xmath4-function, the nonperturbative quantity at the core of hadron physics.
we propose an efficient strategy to suppress epidemic explosion in heterogeneous metapopulation networks, wherein each node represents a subpopulation with any number of individuals and is assigned a curing rate that is proportional to @xmath0 with @xmath1 the node degree and @xmath2 an adjustable parameter.   we have performed stochastic simulations of the dynamical reaction - diffusion processes associated with the susceptible - infected - susceptible model in scale - free networks.   we found that the epidemic threshold reaches a maximum when the exponent @xmath2 is tuned to be @xmath3.   this nontrivial phenomenon is robust to the change of the network size and the average degree.   in addition, we have carried out a mean field analysis to further validate our scheme, which also demonstrates that epidemic explosion follows different routes for @xmath2 larger or less than @xmath4.   our work suggests that in order to efficiently suppress epidemic spreading on heterogeneous complex networks, subpopulations with higher degrees should be allocated more resources than just being linearly dependent on the degree @xmath1.
highly relativistic jets are a key element of current gamma - ray burst models, where the jet kinetic energy is converted to radiation energy at optically thin shocks.   high - energy neutrinos are also expected, from interactions of protons accelerated in the same shocks. here   we revisit the early evolution of a relativistic jet, while the jet is still inside the star, and investigate its neutrino emission.   in particular we study propagation of mildly relativistic and ultrarelativistic jets through a type ib progenitor, and follow reverse shocks as the jets cross the star.   we show that protons can be accelerated to @xmath0@xmath1 gev at reverse shocks, and efficiently produce mesons.   the mesons experience significant cooling, suppressing subsequent neutrino emission.   we show, however, that the neutrino yield from the reverse shock is still reasonably large, especially for low - luminosity and long - duration jets, where meson cooling is less severe.   we discuss implications of our results in the context of neutrinos from choked jets, which are completely shock heated and do not break out of the star. from a choked jet with isotropic equivalent energy of @xmath2 at 10 mpc  , we expect @xmath320 neutrino events at icecube.
large - scale planetary or stellar magnetic fields generated by a dynamo effect are mostly attributed to flows forced by buoyancy forces in electrically conducting fluid layers.   however, these large - scale fields may also be controlled by tides, as previously suggested for the star @xmath0-boo, mars or the early moon. by simulating a small local patch of a rotating fluid  , @xcite have recently shown that tides can drive small - scale dynamos by exciting a hydrodynamic instability, the so - called elliptical ( or tidal ) instability. by performing global magnetohydrodynamic simulations of a rotating spherical fluid body, we investigate if this instability can also drive the observed large - scale magnetic fields.   we are thus interested by the dynamo threshold and the generated magnetic field in order to test if such a mechanism is relevant for planets and stars. rather than solving the problem in a geometry deformed by tides, we consider a spherical fluid body and add a body force to mimic the tidal deformation in the bulk of the fluid.   this allows us to use an efficient spectral code to solve the magnetohydrodynamic problem.   we first compare the hydrodynamic results with theoretical asymptotic results, and numerical results obtained in a truely deformed ellipsoid, which confirms the presence of the elliptical instability.   we then perform magnetohydrodynamic simulations, and investigate the dynamo capability of the flow.   kinematic and self - consistent dynamos are finally simulated, showing that the elliptical instability is capable of generating dipole dominated large - scale magnetic field in global simulations of a fluid rotating sphere.
we ascertain the effectiveness of the second post - newtonian approximation to the gravitational waves emitted during the adiabatic inspiral of a compact binary system as templates for signal searches with kilometer - scale interferometric detectors.   the reference signal is obtained by solving the teukolsky equation for a small mass moving on a circular orbit around a large nonrotating black hole.   fitting factors computed from this signal and these templates, for various types of binary systems, are all above the 90% mark. according to apostolatos criterion  , second post - newtonian waveforms should make acceptably effective search templates.
we review a reduction formula by petersson that reduces the calculation of a one - loop amplitude with @xmath0 external lines in @xmath1 space - time dimensions to the case @xmath2 and give it a geometric interpretation. in the case   @xmath2 the calculation of the euclidean amplitude is shown to be equivalent to the calculation of the volume of a tetrahedron spanned by the momenta in ( @xmath3)-dimensional hyperbolic space.   the underlying geometry is intimately linked to the geometry of the reduction formula.    the geometry of one - loop amplitudes +    oliver schnetz + department mathematik, + universitt erlangen - nrnberg, germany + october 2010 +
the contribution of white dwarfs of the different galactic populations to the stellar content of our galaxy is only poorly known.   some authors claim a vast population of halo white dwarfs, which would be in accordance with some investigations of the early phases of galaxy formation claiming a top - heavy initial  mass  function.   here, i present a model of the population of white dwarfs in the milky way based on observations of the local white dwarf sample and a standard model of galactic structure.   this model will be used to estimate the space densities of thin disc, thick disc and halo white dwarfs and their contribution to the baryonic mass budget of the milky way.   one result of this investigation is that white dwarfs of the halo population contribute a large fraction of the galactic white dwarf number count, but they are not responsible for the lion s share of stellar mass in the milky way.   another important result is the substantial contribution of the  often neglected  population of thick disc white dwarfs.   misclassification of thick disc white dwarfs is responsible for overestimates of the halo population in previous investigations.
phase coherence and vortex order in the fully frustrated xy model on a two - dimensional honeycomb lattice are studied by extensive monte carlo simulations using the parallel tempering method and finite - size scaling.   no evidence is found for an equilibrium order - disorder or a spin / vortex - glass transition, suggested in previous simulation works. instead  , the scaling analysis of correlations of phase and vortex variables in the full equilibrated system is consistent with a phase transition where the critical temperature vanishes and the correlation lengths diverge as a power - law with decreasing temperatures and corresponding critical exponents @xmath0 and @xmath1.   this behavior and the near agreement of the critical exponents suggest a zero - temperature transition scenario where phase and vortex variables remain coupled on large length scales.
the quasi - periodic doubling cascade is shown to occur in the transition from regular to weakly turbulent behaviour in simulations of incompressible navier - stokes flow on a three - periodic domain.   special symmetries are imposed on the flow field in order to reduce the computational effort.   thus we can apply tools from dynamical systems theory such as continuation of periodic orbits and computation of lyapunov exponents.   we propose a model ode for the quasi - period doubling cascade which, in a limit of a perturbation parameter to zero, avoids resonance related problems. the cascade we observe in the simulations   is then compared to the perturbed case, in which resonances complicate the bifurcation scenario. in particular, we compare the frequency spectrum and the lyapunov exponents. the perturbed model ode is shown to be in good agreement with the simulations of weak turbulence.   the scaling of the observed cascade is shown to resemble the unperturbed case, which is directly related to the well known doubling cascade of periodic orbits.   transition to turbulence, torus bifurcation.   5.45.jn, 47.20.kg, 47.27.cn
real data are constrained to finite sampling rates, which calls for a suitable mathematical description of the corrections to the finite - time estimations of the dynamic equations. often in the literature,   lower order discrete time approximations of the modeling diffusion processes are considered. on the other hand,   there is a lack of simple estimating procedures based on higher order approximations. for standard diffusion models, that include additive and multiplicative noise components,   we obtain the exact corrections to the empirical finite - time drift and diffusion coefficients, based on it - taylor expansions.   these results allow to reconstruct the real hidden coefficients from the empirical estimates.   we also derive higher - order finite - time expressions for the third and fourth conditional moments, that furnish extra theoretical checks for that class of diffusive models.   the theoretical predictions are compared with the numerical outcomes of some representative artificial time - series.
preliminary results from a study of the isotopic compositions of the elements hg and pt in a number of hgmn stars are presented.   this work represents an improvement over previous studies thanks to the very high spectral resolution available ( r = 118 000 ) and to the new information on wavelengths and atomic structure of  and.
many schemes to realize quantum state transfer in spin chains are not robust to random fluctuations in the spin - spin coupling strength. in efforts to achieve robust quantum state transfer,   an adiabatic quantum population transfer scheme is proposed in this study.   the proposed scheme makes use of a slowly moving external parabolic potential and is qualitatively explained in terms of the adiabatic following of a quantum state with a moving separatrix structure in the classical phase space of a pendulum analogy.   detailed aspects of our adiabatic population transfer scheme, including its robustness, is studied computationally.   applications of our adiabatic scheme in quantum information transfer are also discussed, with emphasis placed on the usage of a dual spin chain to encode quantum phases.   the results should also be useful for the control of electron tunneling in an array of quantum dots.
the analysis of new experimental data, obtained at the proton linear accelerator of inr, with the aim to search for supernarrow dibaryons in the @xmath0 and @xmath1 reactions is presented.   narrow peaks with an experimental width of 5 mev at masses of 1904@xmath2, 1926@xmath2, and 1942@xmath2 mev have been observed in missing mass @xmath3 spectra. in the missing mass @xmath4 spectra, the peaks at @xmath5, 986@xmath2, and 1003@xmath2 mev have been found.   the analysis of the data obtained leads to the conclusion that the observed peaks in @xmath3 spectra are most likely supernarrow dibaryons, the decay of which into two nucleons is forbidden by the pauli exclusion principle.   an alternative interpretation of the spectra by assuming a decay of the supernarrow dibaryons in `` exotic baryon states '' with masses @xmath4 is discussed.   +    * new evidence for supernarrow dibaryons production in @xmath6 interactions * +    l.v.   filkov@xmath7, v.l.   kashevarov@xmath7, e.s.konobeevski@xmath8, m.v.   mordovskoy@xmath8, + s.i.   potashev@xmath8, v.a.   simonov@xmath8, v.m.   skorkin@xmath8, s.v.   zuev@xmath8    @xmath9 lebedev physical institute, ras, leninsky prospect 53, 117924 moscow, r
we consider the dependences of the average number of interacting nucleons in high energy heavy ion collisions on the impact parameter in two cases, when the colliding nuclei have equal atomic weights, and when one nucleus is significantly more heavy in comparison with the second one.   we argue that in the case of trigger of some rare event ( say, @xmath0, or @xmath1 production ) the multiplicity of the secondaries can change several times for minimum bias sample, but it should be stable in the case of central events.   = 0.7 cm    1.5 truecm * impact parameter dependences of the number of interacting nucleons and mean multiplicities in high energy heavy ion interactions * + c.pajares + departamento de fisica de particulas, universidade de santiago de compostela, 15706-santiago de compostela, spain + and + yu.m.shabelski + petersburg nuclear physics institute, + gatchina, st.petersburg 188350 russia +
superconducting persistent - current qubits are quantum - coherent artificial atoms with multiple, tunable energy levels. in the presence of large - amplitude harmonic excitation  , the qubit state can be driven through one or more of the constituent energy - level avoided crossings.   the resulting landau - zener - stckelberg ( lzs ) transitions mediate a rich array of quantum - coherent phenomena.   we review here three experimental works based on lzs transitions : mach - zehnder - type interferometry between repeated lzs transitions, microwave - induced cooling, and amplitude spectroscopy.   these experiments exhibit a remarkable agreement with theory, and are extensible to other solid - state and atomic qubit modalities.   we anticipate they will find application to qubit state - preparation and control methods for quantum information science and technology.
the full counting statistics of charge transport is the probability distribution @xmath0 that @xmath1 electrons have flown through the system in measuring time @xmath2.   the cumulant generating function ( cgf ) of this distribution @xmath3 has been well studied in the long time limit @xmath4, however there are relatively few results on the finite measuring time corrections to this. in this work,   we study the leading finite time corrections to the cgf of interacting fermi systems with a single transmission channel at zero temperature but driven out of equilibrium by a bias voltage.   we conjecture that the leading finite time corrections are logarithmic in @xmath2 with a coefficient universally related to the long time limit.   we provide detailed numerical evidence for this with reference to the self - dual interacting resonant level model.   this model further contains a phase transition associated with the fractionalisation of charge at a critical bias voltage.   this transition manifests itself technically as branch points in the cgf.   we provide numerical results of the dependence of the cgf on measuring time for model parameters in the vicinity of this transition, and thus identify features in the time evolution associated with the phase transition itself.
we study the discrete gierer - meinhardt model of reaction - diffusion on three different types of networks : regular, random and scale - free.   the model dynamics lead to the formation of stationary turing patterns in the steady state in certain parameter regions. some general features of the patterns are studied through numerical simulation.   the results for the random and scale - free networks show a marked difference from those in the case of the regular network.   the difference may be ascribed to the small world character of the first two types of networks.   keywords : reaction - diffusion, turing patterns, random and scale - free networks, activator, inhibitor
we study an inflationary scenario with a vector impurity.   we show that the universe undergoes anisotropic inflationary expansion due to a preferred direction determined by the vector. using the slow - roll approximation  , we find a formula to determine anisotropy of the inflationary universe.   we discuss possible observable predictions of this scenario.   in particular, it is stressed that primordial gravitational waves can be induced from curvature perturbations.   hence, even in low scale inflation, a sizable amount of primordial gravitational waves may be produced during inflation.
we report on the recovery of the six old novae el aql, v606 aql, v908 oph, v1149 sgr, v1583 sgr and v3964 sgr, using photometric and spectroscopic data.   analysing several properties, we find that el aql is a good candidate for an intermediate polar.   furthermore, the system inclination of el aql, v606 aql, v1583 sgr and v3964 sgr appears to be sufficiently high to suggest them as good targets for time series observations.   we also eliminate some previously suggested candidates for the post - novae v1301 aql and v1151 sgr.       novae, cataclysmic variables
we study phase transitions in classical spin ice at nonzero magnetization, by introducing a mean - field theory designed to capture the interplay between confinement and topological constraints.   the method is applied to a model of spin ice in an applied magnetic field along the @xmath0 $ ] crystallographic direction and yields a phase diagram containing the coulomb phase as well as a set of magnetization plateaux.   we argue that the lobe structure of the phase diagram, strongly reminiscent of the bose   hubbard model, is generic to coulomb spin liquids.
we describe a spectroscopic survey designed to uncover an estimated @xmath040 am cvn stars hiding in the photometric database of the sloan digital sky survey ( sdss ).   we have constructed a relatively small sample of about 1,500  candidates based on a colour selection, which should contain the majority of all am cvn binaries while remaining small enough that spectroscopic identification of the full sample is feasible.   we present the first new am cvn star discovered using this strategy, sdssj080449.49 + 161624.8, the ultracompact binary nature of which is demonstrated using high - time - resolution spectroscopy obtained at the magellan telescopes at las campanas observatory, chile. a kinematic ` s - wave'feature   is observed on a period @xmath1min, which we propose is the orbital period, although the present data can not yet exclude its nearest daily aliases.   the new am cvn star shows a peculiar spectrum of broad, single - peaked helium emission lines with unusually strong series of ionised helium, reminiscent of the ( intermediate ) polars among the hydrogen - rich cataclysmic variables.   we speculate that sdssj0804 + 1616  may be the first magnetic am cvn star.   the accreted material appears to be enriched in nitrogen, to n / o@xmath210 and n / c@xmath310 by number, indicating cno - cycle hydrogen burning, but no helium burning, in the prior evolution of the donor star.        stars : individual : sdssj080449.49 + 161624.8  binaries : close  white dwarfs  novae, cataclysmic variables  accretion, accretion discs
we develop a finite temperature perturbation theory ( beyond the mean field ) for a bose - condensed gas and calculate temperature - dependent damping rates and energy shifts for bogolyubov excitations of any energy.   the theory is generalized for the case of excitations in a spatially inhomogeneous ( trapped ) bose - condensed gas, where we emphasize the principal importance of inhomogeneity of the condensate density profile and develop the method of calculating the self - energy functions.   the use of the theory is demonstrated by calculating the damping rates and energy shifts of low - energy quasiclassical excitations, i.e. the quasiclassical excitations with energies much smaller than the mean field interaction between particles. in this case   the boundary region of the condensate plays a crucial role, and the result for the damping rates and energy shifts is completely different from that in spatially homogeneous gases.   we also analyze the frequency shifts and damping of sound waves in cylindrical bose condensates and discuss the role of damping in the recent mit experiment on the sound propagation.
growth dynamic of real networks because of emerging complexities is an open and interesting question.   indeed it is not realistic to ignore history impact on the current events.   the mystery behind that complexity could be in the role of history in some how. to regard this point,   the average effect of history has been included by a kernel function in differential equation of barab@xmath0si albert ( ba ) model.   this approach leads to a fractional order ba differential equation as a generalization of ba model. as opposed to unlimited growth for degree of nodes,   our results show that over time the memory impact will cause a decay for degrees.   this gives a higher chance to younger members for turning to a hub.   in fact in a real network, there are two competitive processes. on one hand, based on preferential attachment mechanism nodes with higher degree are more likely to absorb links. on the other hand, node history through aging process   prevents new connections.   our findings from simulating a network grown by considering these effects also from studying a real network of collaboration between hollywood movie actors conforms the results and significant effects of history and time on dynamic.
the reaction - diffusion master equation is a stochastic model often utilized in the study of biochemical reaction networks in living cells.   it is applied when the spatial distribution of molecules is important to the dynamics of the system. a viable approach   to resolve the complex geometry of cells accurately is to discretize space with an unstructured mesh.   diffusion is modeled as discrete jumps between nodes on the mesh, and the diffusion jump rates can be obtained through a discretization of the diffusion equation on the mesh.   reactions can occur when molecules occupy the same voxel. in this paper  , we develop a method for computing accurate reaction rates between molecules occupying the same voxel in an unstructured mesh. for large voxels,   these rates are known to be well approximated by the reaction rates derived by collins and kimball, but as the mesh is refined, no analytical expression for the rates exists.   we reduce the problem of computing accurate reaction rates to a pure preprocessing step, depending only on the mesh and not on the model parameters, and we devise an efficient numerical scheme to estimate them to high accuracy.   we show in several numerical examples that as we refine the mesh, the results obtained with the reaction - diffusion master equation approach those of a more fine - grained smoluchowski particle - tracking model.
we argue that a system of straight rigid rods of length @xmath0 on square lattice with only hard - core interactions shows two phase transitions as a function of density @xmath1 for @xmath2.   the system undergoes a phase transition from the low - density disordered phase to a nematic phase as @xmath1 is increased from @xmath3 at @xmath4, and then again undergoes a reentrant phase transition from the nematic phase to a disordered phase at @xmath5.
we investigate the evolution of the bound state of negatively charged massive particles ( champs ) with light elements and discuss its cosmological consequences and the constraint. by numerically solving the boltzmann equation, we study the time evolutions of such bound states.   since most of negative champs are captured by @xmath0, its bound state is positively charged and couples with the electromagnetic plasma.   when charged particles constitute a dominant non - relativistic component, density fluctuations of matter can not grow due to the acoustic damping.   this results in the suppression of matter power spectrum from which a severe constraint can be obtained. by arguing constraints from other aspects of cosmology,   we show that the constraint from large scale structure gives most stringent one in some representative cases.   tu-851 + september, 2009 +.5 in    * cosmology with long - lived charged + massive particles *   .45 in    kazunori kohri@xmath1 and tomo takahashi@xmath2   .45 in    _ @xmath3 department of physics, tohoku university, sendai 980 - 8578, japan + @xmath4 physics department, lancaster university, lancaster la1 4yb, uk + @xmath2 department of physics, saga university, saga 840 - 8502, japan + _   .45 in
we derive approximate equations of motion for excited state dynamics of a multilevel open quantum system weakly interacting with light to describe fluorescence detected single molecule spectra. based on the frenkel exciton theory,   we construct a model for the chlorophyll part of the lhcii complex of higher plants and its interaction with previously proposed excitation quencher in the form of the lutein molecule lut 1.   the resulting description is valid over a broad range of timescales relevant for single molecule spectroscopy, i.e. from ps to minutes.   validity of these equations is demonstrated by comparing simulations of ensemble and single - molecule spectra of monomeric lhcii with experiments. using a conformational change of the lhcii protein as a switching mechanism, the intensity and spectral time traces of individual lhcii complexes are simulated, and the experimental statistical distributions are reproduced. based on our model  , it is shown that with reasonable assumptions about its interaction with chlorophylls, lut 1 can act as an efficient fluorescence quencher in lhcii.   = 1
relativistic models developed for the exclusive and inclusive quasielastic ( qe ) electron scattering have been extended to charged - current ( cc ) and neutral - current ( nc ) neutrino - nucleus scattering.   different descriptions of final - state interactions ( fsi ) are compared. for the inclusive electron scattering the relativistic green s function approach   is compared with calculations based on the use of relativistic purely real mean field potentials in the final state.   both approaches lead to a redistribution of the strength but conserving the total flux.   results for the differential cross section at different energies are presented.   scaling properties are also analyzed and discussed.
we present a semiempirical pseudopotential method based on screened atomic pseudopotentials and derived from _ ab initio _ calculations.   this approach is motivated by the demand for pseudopotentials able to address nanostructures, where _ ab initio _ methods are both too costly and insufficiently accurate at the level of the local - density approximation, while mesoscopic effective - mass approaches are inapplicable due to the small size of the structures along, at least, one dimension. in this work   we improve the traditional pseudopotential method by a two - step process : first, we invert a set of self - consistently determined screened _ ab initio _ potentials in wurtzite gan for a range of unit cell volumes, thus determining spherically - symmetric and structurally averaged atomic potentials.   second, we adjust the potentials to reproduce observed excitation energies. we find that the adjustment represents a reasonably small perturbation over the potential, so that the ensuing potential still reproduces the original wave functions, while the excitation energies are significantly improved.   we furthermore deal with the passivation of the dangling bonds of free surfaces which is relevant for the study of nanowires and colloidal nanoparticles.   we present a methodology to derive passivant pseudopotentials from _ ab initio _ calculations.   we apply our pseudopotential approach to the exploration of the confinement effects on the electronic structure of gan nanowires.
high spatial and spectral resolution spectroscopy of the oh / ir supergiant vy cma and its circumstellar ejecta reveals evidence for high mass loss events from localized regions on the star occurring over the past 1000 years.   the reflected absorption lines and the extremely strong k i emission lines show a complex pattern of velocities in the ejecta.   we show that the large, dusty nw arc, expanding at @xmath0 50 km s@xmath1 with respect to the embedded star, is kinematically distinct from the surrounding nebulosity and was ejected about 400 years ago.   other large, more filamentary loops were probably expelled as much as 800 to 1000 years ago while knots and small arcs close to the star resulted from more recent events 100 to 200 years ago. _   the more diffuse, uniformly distributed gas and dust is surprisingly stationary with little or no velocity relative to the star.   _ this is not what we would expect for the circumstellar material from an evolved red supergiant with a long history of mass loss.   we therefore suggest that the high mass loss rate for vy cma is a measure of the mass carried out by these specific ejections accompanied by streams or flows of gas through low density regions in the dust envelope.   vy cma may thus be our most extreme example of stellar activity, but our results also bring into question the evolutionary state of this famous star. in a separate appendix  , we discuss the origin of the very strong k i and other rare emission lines in its spectrum.
the grover quantum search algorithm is generalized to deal with an arbitrary mixed initial state.   the probability to measure a marked state as a function of time is calculated, and found to depend strongly on the specific initial state.   the form of the function, though, remains as it is in the case of initial pure state.   we study the role of the von neumann entropy of the initial state, and show that the entropy can not be a measure for the usefulness of the algorithm.   we give few examples and show that for some extremely mixed initial states ( carrying high entropy ), the generalized grover algorithm is considerably faster than any classical algorithm.   +   + doi : 10.1103/physreva.66.062301 pacs number(s ) : 03.67.lx    # 1    # 1#1
we study a model for polaron - like charge transport mechanism along dna molecules with emphasis on the impact of parametrical and structural disorder.   our model hamiltonian takes into account the coupling of the charge carrier to two different kind of modes representing fluctuating twist motions of the base pairs and h - bond distortions within the double helix structure of @xmath0dna.   localized stationary states are constructed with the help of a nonlinear map approach for a periodic double helix and in the presence of intrinsic static parametrical and/or structural disorder reflecting the impact of ambient solvent coordinates.   it is demonstrated that charge transport is mediated by moving polarons respectively breather compounds carrying not only the charge but causing also local temporal deformations of the helix structure through the traveling torsion and bond breather components illustrating the interplay of structure and function in biomolecules.   ,   ,   ,    87.-15.v,,63.20.kr, 63.20.ry
we study the nonequilibrium spectral function of the single - impurity anderson model connecting with multi - terminal leads.   the full dependence on frequency and bias voltage of the nonequilibrium self - energy and spectral function is obtained analytically up to the second - order perturbation regarding the interaction strength @xmath0.   high and low bias voltage properties are analyzed for a generic multi - terminal dot, showing a crossover from the kondo resonance to the coulomb peaks with increasing bias voltage. for a dot where the particle - hole symmetry is not present,   we construct a current - preserving evaluation of the nonequilibrium spectral function for arbitrary bias voltage.   it is shown that finite bias voltage does not split the kondo resonance in this order, and no specific structure due to multiple leads emerges.   overall bias dependence is quite similar to finite temperature effect for a dot with or without the particle - hole symmetry.
in this work, the effects of quantum interference and spontaneously generated coherence ( sgc ) are theoretically analyzed in a four level system of a @xmath0 atom. for the effects of sgc  , we find that a new kind of eit channel can be induced due to destructive interference, and the nonlinear kerr absorption can be coherently narrowed or eliminated under different strengths of the coupling and switching fields.
let @xmath0 be a connected nonorientable surface of genus @xmath1 with @xmath2 punctures.   suppose that @xmath1 is odd and @xmath3.   we prove that the automorphism group of the complex of curves of @xmath0 is isomorphic to the mapping class group @xmath4 of @xmath0.
malin 1 has long been considered a prototype giant, dark matter dominated low surface brightness galaxy.   two recent studies, one based on a re - analysis of vla hi  observations and the other on an archival hubble i - band image, throw a new light on this enigmatic galaxy and on its dark / luminous matter properties.
the one - dimensional repulsive su@xmath0 hubbard model is investigated analytically by bosonization approach and numerically using the density - matrix renormalization - group ( dmrg ) method for @xmath1, and @xmath2 for commensurate fillings @xmath3 where @xmath4 and @xmath5 are relatively prime.   it is shown that the behavior of the system is drastically different depending on whether @xmath6, @xmath7, or @xmath8. when @xmath6, the umklapp processes are irrelevant, the model is equivalent to an @xmath9-component luttinger liquid with central charge @xmath10.   when @xmath7, the charge and spin modes are decoupled, the umklapp processes open a charge gap for finite @xmath11, whereas the spin modes remain gapless and the central charge @xmath12.   the translational symmetry is not broken in the ground state for any @xmath9.   on the other hand, when @xmath8, the charge and spin modes are coupled, the umklapp processes open gaps in all excitation branches, and a spatially nonuniform ground state develops.   bond - ordered dimerized, trimerized or tetramerized phases are found depending on the filling.
in this paper, we have investigated theoretically the influence of atomic collisions on the behaviour of a one - dimensional bose - einstein condensate inside a driven optical cavity.   we develop the discrete - mode approximation for the condensate taking into account the interband transitions due to the s - wave scattering interaction.   we show that in the bogoliubov approximation the atom - atom interaction shifts the energies of the excited modes and also plays the role of an optical parametric amplifier for the bogoliubov side mode which can affect its normal - mode splitting behaviour. on the other hand due to the atomic collisions the resonance frequency of the cavity   is shifted which leads to the decrease of the number of cavity photons and the depletion of the bogoliubov mode.   besides, it reduces the effective atom - photon coupling parameter which consequently leads to the decrease of the entanglement between the bogoliubov mode and the optical field.
we have first successfully transferred the @xmath0xe polarization of natural isotopic composition to the proton of solid - state @xmath1hcl via spin polarization - induced nuclear overhauser effect ( spinoe ), by mixing the hyperpolarized @xmath0xe gas and the @xmath1hcl gas and then cooling them to their condensated state in a flow system.   the solid - state enhanced factor of the nmr signal of 6 for @xmath1h was observed, and the equation of solid - state polarization enhancement via cross relaxation has also been theoretically deduced. using this equation,   the theoretically calculated enhancement is in agreement with the measured value within error. also, this technique is maybe useful to establish a solid state nmr quantum computer.   pacs number(s ) : 32.80.bx, 33.25.+k, 03.67.lx
we compute the lyapunov exponents and the kolmogorov - sinai ( ks ) entropy for a self - bound @xmath0-body system that is realized as a convex billiard.   this system exhibits truly high - dimensional chaos, and @xmath1 lyapunov exponents are found to be positive.   the ks entropy increases linearly with the numbers of particles.   we examine the chaos generating defocusing mechanism and investigate how high - dimensional chaos develops in this system with no dispersing elements.
the effects of randomly pinning particles in a model glass - forming fluid are studied, with a focus on the dynamically heterogeneous relaxation in the presence of pinning.   we show how four - point dynamical correlations can be analysed in real space, allowing direct extraction of a length scale that characterises dynamical heterogeneity. in the presence of pinning,   the relaxation time of the glassy system increases by up to two decades, but there is almost no increase in either the four - point correlation length or the strength of the four - point correlations.   we discuss the implications of these results for theories of the glass transition.
we present theoretical modelling for the very rapid tev variability of pks 2155304 observed recently by the h.e.s.s. experiment.   to explain the light - curve, where at least five flaring events were well observed, we assume five independent components of a jet that are characterized by slightly different physical parameters.   an additional, significantly larger component is used to explain the emission of the source at long time scales.   this component dominates the emission in the x - ray range, whereas the other components are dominant in the tev range.   the model used for our simulation describes precisely the evolution of the particle energy spectrum inside each component and takes into account light travel time effects.   we show that a relatively simple synchrotron self - compton scenario may explain this very rapid variability. moreover, we find that absorption of the tev emission inside the components due to the pair creation process is negligible.       radiative transfer  bl lacertae objects : individual : pks  2155304
when a local potential changes abruptly in time, an electron gas responds by shifting to a new state which at long times is orthogonal to the one in the absence of the local potential.   this is known as anderson s orthogonality catastrophe and it is relevant for the so - called x - ray edge or fermi edge singularity, and for tunneling into an interacting one dimensional system of fermions.   it often happens that the finite frequency response of the photon absorption or the tunneling density of states exhibits a singular behavior as a function of frequency : @xmath0 where @xmath1 is a threshold frequency and @xmath2 is an exponent characterizing the singular response. in this paper singular responses of spin - incoherent luttinger liquids are reviewed.   such responses most often do not fall into the familiar form above, but instead typically exhibit logarithmic corrections and display a much higher universality in terms of the microscopic interactions in the theory.   specific predictions are made, the current experimental situation is summarized, and key outstanding theoretical issues related to spin - incoherent luttinger liquids are highlighted.
jet quenching in the matter created in high energy nucleus - nucleus collisions provides a tomographic tool to probe the medium properties.   recent experimental results from the relativistic heavy - ion collider ( rhic ) on characterization of jet production via dihadron correlations at high transverse momentum are reviewed.   expectations from the dihadron measurements for the lower energy = 62.4 gev rhic run are discussed.    2
we consider a friedmann - robertson - walker spacetime filled with both viscous radiation and nonviscous dust.   the former has a bulk viscosity which is proportional to an arbitrary power of the energy density, _   i.e. _ @xmath0, and viscous pressure satisfying a nonlinear evolution equation.   the analysis is carried out in the context of dynamical systems and the properties of solutions corresponding to the fixed points are discussed. for some ranges of the relevant parameter @xmath1   we find that the trajectories in the phase space evolve from a frw singularity towards an asymptotic de sitter attractor, confirming and extending previous analysis in the literature.   for other values of the parameter, instead, the behaviour differs from previous works.
we propose a disk encryption method, called secure disk mixed system ( sdms ) in this paper, for data protection of disk storages such as usb flash memory, usb hard disk and cd / dvd.   it is aimed to solve temporal and spatial limitation problems of existing disk encryption methods and to control security performance flexibly according to the security requirement of system.   sdms stores data by encrypting with different encryption key per sector and updates sector encryption keys each time data is written.   security performance of sdms is analyzed at the end of the paper.
the one - dimensional scattering of a two body interacting system by an infinite wall is studied in a quantum - mechanical framework.   this problem contains some of the dynamical features present in the collision of atomic, molecular and nuclear systems.   the scattering problem is solved exactly, for the case of a harmonic interaction between the fragments.   the exact result is used to assess the validity of two different approximations to the scattering process.   the adiabatic approximation, which considers that the relative co - ordinate is frozen during the scattering process, is found to be inadequate for this problem.   the uncorrelated scattering approximation, which neglects the correlation between the fragments, gives results in accordance with the exact calculations when the scattering energy is high compared to the oscillator parameter.   * one dimensional scattering of a two body interacting system by an infinite wall *     +
we investigated the impacts of magnetorotational instability ( mri ) on the dynamics of weakly magnetized, rapidly rotating core - collapse by conducting high resolution mhd simulations in axisymmetry with simplified neutrino transfer.   we found that an initially sub - magnetar class magnetic field is drastically amplified by mri and substantially affects the dynamics thereafter.   although the magnetic pressure is not strong enough to eject matter, the amplified magnetic field efficiently transfers angular momentum from higher to lower latitudes, which causes the expansion of the heating region at low latitudes due to the extra centrifugal force.   this then enhance the efficiency of neutrino heating and eventually leads to neutrino - driven explosion.   this is a new scenario of core - collapse supernovae that has never been demonstrated by numerical simulations so far.
scalar - tensor theories of gravity provide a consistent framework to accommodate an ultra - light quintessence scalar field.   while the equivalence principle is respected by construction, deviations from general relativity and standard cosmology may show up at nucleosynthesis, cmb, and solar system tests of gravity. after imposing all the bounds coming from these observations, we consider the expansion rate of the universe at wimp decoupling, showing that it can lead to an enhancement of the dark matter relic density up to few orders of magnitude with respect to the standard case.   this effect can have an impact on supersymmetric candidates for dark matter.
many things will have to go right for quantum computation to become a reality in the lab.   for any of the presently - proposed approaches involving spin states in solids, an essential requirement is that these spins should be measured at the single - bohr - magneton level.   fortunately, quantum computing provides a suggestion for a new approach to this seemingly almost impossible task : convert the magnetization into a charge, and measure the charge.   i show how this might be done by exploiting the spin filter effect provided by ferromagnetic tunnel barriers, used in conjunction with one - electron quantum dots.
catastrophes of all kinds can be roughly defined as short duration - large amplitude events following and followed by long periods of `` ripening ''.   major earthquakes surely belong to the class of ` catastrophic'events. because of the space - time scales involved, an experimental approach is often difficult, not to say impossible, however desirable it could be.   described in this article is a `` laboratory '' setup that yields data of a type that is amenable to theoretical methods of prediction.   observations are made of a critical slowing down in the noisy signal of a solder wire creeping under constant stress.   this effect is shown to be a fair signal of the forthcoming catastrophe in both of two dynamical models.   the first is an `` abstract '' model in which a time dependent quantity drifts slowly but makes quick jumps from time to time.   the second is a realistic physical model for the collective motion of dislocations ( the ananthakrishna set of equations for creep ).   hope thus exists that similar changes in the response to noise could forewarn catastrophes in other situations, where such precursor effects should manifest early enough.
we present a model for the inverted radio spectra of active active galactic nuclei as well as the central regions of normal galaxies.   the model is based on the unified scenario for active galaxies, stating that the central engines of active galaxies consists of a supermassive black hole surrounded by an accretion disk and a radio jet.   the nuclei of normal ( i. e. less active ) galaxies are supposed to be scaled - down versions of the same phenomenon.   we show that the radio emission of a jet component, becoming optically thin to the radio emission of a monoenergetic pair plasma at decreasing frequencies as it moves outward and expands, is well suited to explain the observational results.   we present a model calculation for the special case of the nucleus of m  81.
we prove that every legendrian knot in the tight contact structure of the @xmath0-sphere is determined by the contactomorphism type of its exterior. moreover,   by giving counterexamples we show this to be not true for legendrian links in the tight @xmath0-sphere and for legendrian knots in arbitrary contact manifolds. on the way a new user - friendly formula for computing the thurston - bennequin invariant of a legendrian knot in a surgery diagram   is given.
the cosmic background explorer ( _ cobe _ ) satellite, and the differential microwave radiometer ( dmr ) experiment in particular, was extraordinarily successful.   however, the dmr results were announced about 7 years ago, during which time a great deal more has been learned about anisotropies in the cosmic microwave background ( cmb ).   we assess the current state of knowledge, and discuss where we might be going.   the cmb experiments currently being designed and built, including long - duration balloons, interferometers, and two space missions, promise to address several fundamental cosmological issues.   we present our evaluation of what we already know, what we are beginning to learn now, and what the future may bring.   _ all right.   but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, the fresh water system, and public health  what have the romans ever done for us? _
using direct numerical simulations of rayleigh - bnard convection ( rbc ), we perform a comparative study of the spectra and fluxes of energy and entropy, and the scaling of large - scale quantities for large and infinite prandtl numbers in two ( 2d ) and three ( 3d ) dimensions.   we observe close similarities between the 2d and 3d rbc, in particular the kinetic energy spectrum @xmath0, and the entropy spectrum exhibits a dual branch with a dominant @xmath1 spectrum.   we showed that the dominant fourier modes in the 2d and 3d flows are very close.   consequently, the 3d rbc is quasi two - dimensional, which is the reason for the similarities between the 2d and 3d rbc for large- and infinite prandtl numbers.
gravitational waves and x - ray flares are expected from tidal disruption of stars by a massive black hole. using a relativistic smoothed particle hydrodynamics code  , we investigate the fate of main sequence and helium stars in plunge orbits passing near schwarzschild or a kerr black holes of mass @xmath0.   we show that quadrupole gravitational waves emitted during the tidal disruption process are described reasonable well by a point particle approximation even in the strong encounter case.   an additional hydrodynamic calculation based on the godunov method indicates that shocks develop for sufficiently high tidal compressions.   the shock - heating results in an x - ray flare, which for solar - type stars disrupted by @xmath1 black holes is in the kev range, associated with the gravitational wave signal.   the hardness and duration of the x - ray flare may serve as a diagnostic of the mass of the central black hole.
cosmological shock waves result from supersonic flow motions induced by hierarchical clustering of nonlinear structures in the universe.   these shocks govern the nature of cosmic plasma through thermalization of gas and acceleration of nonthermal, cosmic - ray ( cr ) particles.   we study the statistics and energetics of shocks formed in cosmological simulations of a concordance @xmath0cdm universe, with a special emphasis on the effects of non - gravitational processes such as radiative cooling, photoionization / heating, and galactic superwind feedbacks. adopting an improved model for gas thermalization and cr acceleration efficiencies based on nonlinear diffusive shock acceleration calculations  , we then estimate the gas thermal energy and the cr energy dissipated at shocks through the history of the universe.   since shocks can serve as sites for generation of vorticity, we also examine the vorticity that should have been generated mostly at curved shocks in cosmological simulations.   we find that the dynamics and energetics of shocks are governed primarily by the gravity of matter, so other non - gravitational processes do not affect significantly the global energy dissipation and vorticity generation at cosmological shocks.   our results reinforce scenarios in which the intracluster medium and warm - hot intergalactic medium contain energetically significant populations of nonthermal particles and turbulent flow motions.
this talk gives an elementary introduction to the basic properties of positronium.   recent progress in theoretical studies of the hyperfine splitting and lifetime of the ground state is reviewed.   sensitivity of these precisely measured quantities to some new physics effects is discussed.   # 1o(#1 )    = by -1    bnl - het-99/38 + hep - ph/9911455 + november 1999
we calculate an @xmath0-wave amplitude matrix for all the possible 2to2 body scalar boson elastic scatterings in models with three scalar doublets, including contributions from the longitudinal component of weak gauge bosons via the equivalence theorem approximation. specifically, we concentrate on the two cases with two active plus one inert doublet fields, referred to as i(1 + 2)hdm, under cp conservation.   we obtain three analytically irreducible sub - matrices with the @xmath1 form and eighteen eigenvalues for the amplitude matrix as an independent set, where the same formula can be applied to both models. by requiring a perturbative unitarity condition  , we can constrain the magnitude of quartic coupling constants in the higgs potential. this constraint,   in particular in the i(1 + 2)hdm, can be translated into a bound on masses of extra active scalar bosons.   furthermore, when standard model - like higgs boson couplings with weak gauge bosons are deviated from the standard model predictions, the unitarity condition provides an upper limit on the masses.   we find that stronger upper bounds on the masses of the active cp - even and cp - odd higgs bosons are obtained under the constraints from the unitarity and vacuum stability conditions, as well as the electroweak @xmath2, @xmath3 and @xmath4 parameters, as compared to those in 2-higgs doublet models with a softly - broken @xmath5 symmetry.
we show that the crust - core interface in neutron stars acts as a potential barrier to the peripheral neutron vortices approaching the interface in the model in which these are coupled to the proton vortex clusters.   this elementary barrier because of the interaction of vortex magnetic flux with the meissner currents set up by the crustal magnetic field at the interface.   the dominant part of the force is derived from to the cluster - interface interaction. as a result of the stopping of the continuous neutron vortex current through the interface, angular momentum   is stored in the superfluid layers in the vicinity of the crust - core interface during the interglitch period.   discontinuous annihilation of proton vortices on the boundary restores the neutron vortex current and spins up the observable crust on short time - scales, leading to a glitch in the spin characteristics of a pulsar.   latexl-.36em.3ex-.15em t-.1667em.7ex-.125emx    mhd  stars : neutron  pulsars : general  stars : rotation.
the grand canonical formalism is employed to study the thermodynamic structure of a model displaying a quantum phase transition when studied with respect to the canonical formalism.   a numerical survey shows that the grand partition function diverges following a power law when the interaction parameter approaches a limiting constant.   the power - law exponent takes a distinctive value when such limiting constant coincides with the critical point of the subjacent quantum phase transition. an approximated expression for the grand partition function   is derived analytically implementing a mean field scheme and a number of thermodynamic observables are obtained.   the system observables show signatures that can be used to track the critical point of the underlying transition.   this result provides a simple fact that can be exploited to verify the existence of a quantum phase transition avoiding the zero temperature regime.
a spherical gravitational wave antenna is distinct from other types of gravitational wave antennas in that only a single detector is necessary to determine the direction and polarization of a gravitational wave.   zhou and michelson showed that the inverse problem can be solved using the maximum likelihood method if the detector outputs are independent and have normally distributed noise with the same variance.   this paper presents an analytic solution using only linear algebra that is found to produce identical results as the maximum likelihood method but with less computational burden.   applications of this solution to gravitational waves in alternative symmetric metric theories of gravity and impulsive excitations also are discussed.
we fabricated yba@xmath0cu@xmath1o@xmath2 ( ybco ) direct current ( dc ) nano superconducting quantum interference devices ( nanosquids ) based on grain boundary josephson junctions by focused ion beam patterning.   characterization of electric transport and noise properties at 4.2k in magnetically shielded environment yields a very small inductance @xmath3 of a few ph for an optimized device geometry.   this in turn results in very low values of flux noise @xmath4 in the thermal white noise limit, which yields spin sensitivities of a few @xmath5 ( @xmath6 is the magnetic flux quantum and @xmath7 is the bohr magneton ). we observe frequency - dependent excess noise up to 7mhz, which can only partially be eliminated by bias reversal readout.   this indicates the presence of fluctuators of unknown origin, possibly related to defect - induced spins in the srtio@xmath1 substrate.   we demonstrate the potential of using ybco nanosquids for the investigation of small spin systems, by placing a 39 nm diameter fe nanowire, encapsulated in a carbon nanotube, on top of a non - optimized ybco nanosquid and by measuring the magnetization reversal of the fe nanowire via the change of magnetic flux coupled to the nanosquid.   the measured flux signals upon magnetization reversal of the fe nanowire are in very good agreement with estimated values, and the determined switching fields indicate magnetization reversal of the nanowire via curling mode.
the young open cluster collinder  419 surrounds the massive o star, hd  193322, that is itself a remarkable multiple star system containing at least four components. here   we present a discussion of the cluster distance based upon new spectral classifications of the brighter members, @xmath0 photometry, and an analysis of astrometric and photometric data from the ucac3 and 2mass catalogs.   we determine an average cluster reddening of @xmath1 mag and a cluster distance of @xmath2  pc.   the cluster probably contains some very young stars that may include a reddened m3  iii star, iras  20161 + 4035.
the limit theorems of discrete- and continuous - time quantum walks on the line have been intensively studied.   we show a relation among limit distributions of quantum walks, heun differential equations and gauss differential equations.   indeed, we derive the second - order fucksian differential equations which limit density functions of quantum walks satisfy. moreover, using both differential equations, we discuss a relationship between discrete- and continuous - time quantum walks. taking suitable limit, we can transform a heun equation obtained from the limit density function of the discrete - time quantum walk to a gauss equation given by that of the continuous - time quantum walk.
molecular dynamics simulations of 3c - sic have been performed as a function of pressure and temperature.   these simulations treat both electrons and atomic nuclei by quantum mechanical methods.   while the electronic structure of the solid is described by an efficient tight - binding hamiltonian, the nuclei dynamics is treated by the path integral formulation of statistical mechanics. to assess the relevance of nuclear quantum effects,   the results of quantum simulations are compared to others where either the si nuclei, the c nuclei or both atomic nuclei are treated as classical particles.   we find that the experimental thermal expansion of 3c - sic is realistically reproduced by our simulations.   the calculated bulk modulus of 3c - sic and its pressure derivative at room temperature show also good agreement with the available experimental data.   the effect of the electron - phonon interaction on the direct electronic gap of 3c - sic has been calculated as a function of temperature and related to results obtained for bulk diamond and si.   comparison to available experimental data shows satisfactory agreement, although we observe that the employed tight - binding model tends to overestimate the magnitude of the electron - phonon interaction.   the effect of treating the atomic nuclei as classical particles on the direct gap of 3c - sic has been assessed.   we find that non - linear quantum effects related to the atomic masses are particularly relevant at temperatures below 250 k.
we consider a system of two coupled particles evolving in a periodic and spatially symmetric potential under the influence of external driving and damping.   the particles are driven individually in such a way that in the uncoupled regime, one particle evolves on a chaotic attractor, while the other evolves on regular periodic attractors.   notably only the latter supports coherent particle transport.   the influence of the coupling between the particles is explored, and in particular how it relates to the emergence of a directed current.   we show that increasing the ( weak ) coupling strength subdues the current in a process, which in phase - space, is related to a merging crisis of attractors forming one large chaotic attractor in phase - space.   further, we demonstrate that complete current suppression coincides with a chaos - hyperchaos transition.
the nlc extraction line provides a secondary focal point with a low @xmath0 function and 2  cm dispersion which can be used for measurement of the beam energy spectrum. in this study,   tracking simulations were performed to transport the 0.5  tev electron beam from the interaction point ( ip ) to the secondary focus ( sf ), `` measure '' the resultant transverse beam profile and reconstruct the disrupted ip energy spread. in the simulation,   the obtained energy spectrum reproduced the initial ip spread reasonably well, especially with the vertical dispersion at sf which provides larger ratio of dispersion to the betatron beam size.   more details of this study can be found in ref.   @xcite.   slac   pub8871 + june 2001 +    * study of beam energy spectrum measurement + in the nlc extraction line   *    * abstract *     +
in this paper, we consider the implications of the fact that parallel raw - power can be exploited by a generic metropolis   hastings algorithm if the proposed values are independent from the current value of the markov chain.   in particular, we present improvements to the independent metropolis   hastings algorithm that significantly decrease the variance of any estimator derived from the mcmc output, at a null computing cost since those improvements are based on a fixed number of target density evaluations that can be produced in parallel.   the techniques developed in this paper do not jeopardize the markovian convergence properties of the algorithm, since they are based on the rao   blackwell principles of @xcite, already exploited in @xcite, @xcite and @xcite.   we illustrate those improvements both on a toy normal example and on a classical probit regression model, but stress the fact that they are applicable in any case where the independent metropolis  hastings is applicable.   * keywords : * mcmc algorithm, independent metropolis   hastings, parallel computation, rao - blackwellization, permutation.
we study if the parabolic forward - in - time maximal operator is bounded on parabolic @xmath0.   it turns out that for non - negative functions the answer is positive, but the behaviour of sign changing functions is more delicate.   the class parabolic @xmath0 and the forward - in - time maximal operator originate from the regularity theory of nonlinear parabolic partial differential equations.   in addition to that context, we also study the question in dimension one.
we have employed an extensive new timeseries of stokes i and v spectra obtained with the espadons spectropolarimeter at the 3.6-m canada - france - hawaii telescope to investigate the physical parameters, chemical abundance distributions and magnetic field topology of the slowly - rotating he - strong star hd  184927.   we infer a rotation period of @xmath0 from @xmath1, @xmath2, lsd magnetic measurements and ews of helium lines.   we used an extensive nlte tlusty grid along with the synspec code to model the observed spectra and find a new value of luminosity. in this poster   we present the derived physical parameters of the star and the results of magnetic doppler imaging analysis of the stokes i and v profiles.   wide wings of helium lines can be described only under the assumption of the presence of a large, very helium - rich spot.
in remote control, efficient compression or representation of control signals is essential to send them through rate - limited channels. for this purpose  , we propose an approach of sparse control signal representation using the compressive sampling technique.   the problem of obtaining sparse representation is formulated by cardinality - constrained @xmath0 optimization of the control performance, which is reducible to @xmath1 optimization. the low rate random sampling employed in the proposed method based on the compressive sampling, in addition to   the fact that the @xmath1 optimization can be effectively solved by a fast iteration method, enables us to generate the sparse control signal with reduced computational complexity, which is preferable in remote control systems where computation delays seriously degrade the performance.   we give a theoretical result for control performance analysis based on the notion of restricted isometry property ( rip ).   an example is shown to illustrate the effectiveness of the proposed approach via numerical experiments.
tremendous progress has been made recently in modelling the morphology and kinematics of centers of galaxies.   increasingly realistic models are built for central bar, bulge, nucleus and black hole of galaxies, including our own.   the newly revived schwarzschild method has played a central role in these theoretical modellings. here   i will highlight some recent work at leiden on extending the schwarzschild method in a few directions.   after a brief discussion of ( i ) an analytical approach to include stochastic orbits ( zhao 1996 ), and ( ii ) the `` pendulum effect '' of loop and boxlet orbits ( zhao, carollo, de zeeuw 1999 ), i will concentrate on the very promising ( iii ) spectral dynamics method, with which not only can one obtain semi - analytically the actions of individual orbits as previously known, but also many other physical quantities, such as the density in configuration space and the line - of - sight velocity distribution of a superposition of orbits ( copin, zhao & de zeeuw 1999 ).   the latter method also represents a drastic reduction of storage space for the orbit library and an increase in accuracy over the grid - based schwarzschild method.
we perform a time - dependent study of the driven dynamics of overdamped particles which are placed in a one - dimensional, piecewise linear random potential.   this set - up of spatially quenched disorder then exerts a dichotomous varying random force on the particles.   we derive the path integral representation of the resulting probability density function for the position of the particles and transform this quantity of interest into the form of a fourier integral. in doing so  , the evolution of the probability density can be investigated analytically for finite times.   it is demonstrated that the probability density contains both a @xmath0-singular contribution and a regular part. while the former part plays a dominant role at short times, the latter rules the behavior at large evolution times.   the slow approach of the probability density to a limiting gaussian form as time tends to infinity is elucidated in detail.
it has been observed experimentally that under certain conditions pulsed laser deposition ( pld ) produces smoother surfaces than ordinary molecular beam epitaxy ( mbe ).   so far the mechanism leading to the improved quality of surfaces in pld is not yet fully understood. in the present work   we investigate the physical properties of a simple model for pld in which the transient mobility of adatoms and diffusion along edges is neglected. analyzing the crossover from mbe to pld, the scaling properties of the time - dependent nucleation density as well as the influence of ehrlich - schwoebel barriers we find that there is indeed a range of parameters where the surface quality in pld is better than in mbe.   however, since the improvement is weak and occurs only in a small range of parameters we conclude that deposition in pulses alone can not explain the experimentally observed smoothness of pld - grown surfaces.
precision measurements of anisotropies in the cosmic microwave background and of the clustering of large - scale structure have supposedly confirmed that the primordial density perturbation has a ( nearly ) scale - invariant spectrum. however this conclusion is based on assumptions about the world model and the nature of the dark matter.   physical models of inflation suggest that the spectrum may not in fact be scale - free, which would imply rather different cosmological parameters on the basis of the same observational data.
in this paper we analyse the evolutionary status and properties of the old open cluster ngc  2355, located in the galactic anticentre direction, as a part of the long term programme bocce.   ngc  2355 was observed with lbc@lbt using the bessel @xmath0, @xmath1, and @xmath2 filters.   the cluster parameters have been obtained using the synthetic colour - magnitude diagram ( cmd ) method, as done in other papers of this series.   additional spectroscopic observations with fies@not of three giant stars were used to determine the chemical properties of the cluster.   our analysis shows that ngc  2355 has metallicity slightly less than solar, with @xmath3 dex, age between 0.8 and 1 gyr, reddening @xmath4 in the range 0.14 and 0.19 mag, and distance modulus @xmath5 of about 11 mag.   we also investigated the abundances of o, na, al, @xmath6, iron - peak, and neutron capture elements, showing that ngc  2355 falls within the abundance distribution of similar clusters ( same age and metallicity ).   the galactocentric distance of ngc  2355 places it at the border between two regimes of metallicity distribution ; this makes it an important cluster for the study of the chemical properties and evolution of the disc.       hertzsprung - russel and colour - magnitude diagrams, galaxy : disc, open clusters and associations : general, open clusters and associations : individual : ngc 2355.
the lhcb experiment will operate for about five years at a luminosity of @xmath0 and plans are to accumulate a data sample of @xmath1 here we present the physics programme and detector design for a future high luminosity phase of the lhcb experiment.   an upgraded lhcb experiment would operate at ten times the design luminosity, i.e. at @xmath2 and aims to collect a data sample of @xmath3 over five years.   this programme would allow the probe of new physics at an unprecedented level.   key measurements include the @xmath4 mixing phase @xmath5 in  and  decays with a significant sensitivity to the small standard model prediction and a very precise measurement of the ckm angle  @xmath6 in tree diagram decays.   initial studies of the modified lhcb trigger and detectors are presented.   the upgraded lhcb experiment can run with or without an lhc luminosity upgrade.
we present a new type of the hamiltonian replica - exchange method, in which not temperatures but the van der waals radius parameter is exchanged. by decreasing the van der waals radii that control spatial sizes of atoms, this hamiltonian replica - exchange method overcomes the steric restrictions and energy barriers.   furthermore, the simulation based on this method escapes from the local - minimum free - energy states and realizes effective sampling in the conformational space.   we applied this method to an alanine dipeptide in aqueous solution and showed the effectiveness of the method by comparing the results with those obtained from the conventional canonical method.
the loop expansion is applied to a chiral effective hadronic lagrangian ; with the techniques of infrared regularization, it is possible to separate out the short - range contributions and to write them as local products of fields that are already present in our lagrangian.   ( the appropriate field variables must be re - defined at each order in loops. )   the corresponding parameters implicitly include short - range effects to all orders in the interaction, so these effects need not be calculated explicitly. the remaining ( long - range ) contributions that must be calculated are nonlocal and resemble those in conventional nuclear - structure calculations.   nonlinear isoscalar scalar @xmath0 and vector @xmath1 meson interactions are included, which incorporate many - nucleon forces and nucleon substructure.   calculations are carried out at the two - loop level to illustrate these techniques at finite nuclear densities and to verify that the coupling parameters remain natural when fitted to the empirical properties of equilibrium nuclear matter.   contributions from the @xmath2 tensor coupling are also discussed.
we present the results of a search for time correlations in high energy cosmic ray data ( primary @xmath0  ev ) collected by the california high school cosmic ray observatory ( chicos ) array.   data from 69 detector sites spread over an area of 400 km@xmath1 were studied for evidence of isolated events separated by more than 1 km with coincidence times ranging from 1 microseconds up to 1 second.   we report upper limits for the coincidence probability as a function of coincidence time.
the ongoing 11-year cycle of solar activity is considerably less vigorous than the three cycles before.   it was preceded by a very deep activity minimum with a low polar magnetic flux, the source of the toroidal field responsible for solar magnetic activity in the subsequent cycle.   simulation of the evolution of the solar surface field shows that the weak polar fields and thus the weakness of the present cycle 24 are mainly caused by a number of bigger bipolar regions emerging at low latitudes with a ` wrong'( i.e., opposite to the majority for this cycle ) orientation of their magnetic polarities in the north - south direction, which impaired the growth of the polar field.   these regions had a particularly strong effect since they emerged within @xmath0 latitude from the solar equator.
a low - energy @xmath0 collider has been discussed in the context of a testbed for a @xmath0 interaction region at the next linear collider ( nlc ).   we consider the production of heavy mesons at such a testbed using compton - backscattered photons and demonstrate that their production rivals or exceeds those by belle, babar or lep where they are produced indirectly via virtual @xmath0 luminosities.   ucrl - proc-203766
many - electron systems confined to a quasi-1d geometry by a cylindrical distribution of positive charge have been investigated by density functional computations in the unrestricted local spin density approximation.   our investigations have been focused on the low density regime, in which electrons are localised.   the results reveal a wide variety of different charge and spin configurations, including linear and zig - zag chains, single and double - strand helices, and twisted chains of dimers.   the spin - spin coupling turns from weakly anti - ferromagnetic at relatively high density, to weakly ferromagnetic at the lowest densities considered in our computations.   the stability of linear chains of localised charge has been investigated by analysing the radial dependence of the self - consistent potential and by computing the dispersion relation of low - energy harmonic excitations.
an open quantum system consists of leads connected to a device of interest. within the nonequilibrium green s function technique  , we examine the replacement of leads by self - energies in continuum calculations.   our starting point is a formulation of the problem for continuum systems by t.e.   feuchtwang. in this approach   there is considerable flexibility in the choice of unperturbed green s functions.   we examine the consequences of this freedom on the treatment of leads. for any choice   the leads can be replaced by coupling self - energies which are simple functions of energy.   we find that the retarded self - energy @xmath0 depends on the details of the choice of unperturbed green s function, and can take any value.   however, the nonequilibrum self - energy or scattering function @xmath1 can be taken to be independent of this choice.   expressed in terms of these self - energies, nonequilibrium transport calculations take a particularly simple form.
we investigate the properties of the path integral over reparametrizations ( or the boundary value of the liouville field in string theory ). discretizing the path integral  , we apply the metropolis   hastings algorithm to numerical simulations of a proper ( subordinator ) stochastic process and find that typical trajectories are not brownian but rather have discontinuities of the type of lvy s flights.   we study a fractal structure of these trajectories and show that their hausdorff dimension is zero.   we confirm thereby previous results on qcd scattering amplitudes by analytical and numerical calculations.   we also perform monte - carlo simulations of the path integral over reparametrization in the effective string ansatz for a circular wilson loop and discuss their subtleties associated with the discretization of douglas functional.
we investigate quantum phase transitions in two - dimensional superconducting arrays with general capacitance matrices and discrete charge states.   we use the perturbation theory together with the simulated annealing method to obtain the zero - temperature phase diagrams, which display various lobe - like structures of insulating solid phases, and examine the possibility of supersolid phase. at nonzero temperatures,   an effective classical hamiltonian is obtained through the use of the variational method in the path - integral formalism, and the corresponding phase diagram is found approximately.   the insulating lobes of the solid phases are shown to exist at sufficiently low temperatures, and results of monte carlo simulations are also presented.    2
i - v characteristics of the high t@xmath0 superconductor bi@xmath1sr@xmath1ca@xmath2c@xmath1o@xmath3 shows a strong hysteresis, producing many branches.   the origin of hysteresis jumps is studied by use of the model of multi - layered josephson junctions proposed by one of the authors ( t. k. ).   the charging effect at superconducting layers produces a coupling between the next nearest neighbor phase - differences, which determines the structure of hysteresis branches.   it will be shown that a solution of phase motions is understood as a combination of rotating and oscillating phase - differences, and that, at points of hysteresis jumps, there occurs a change in the number of rotating phase - differences.   effects of dissipation are analyzed.   the dissipation in insulating layers works to damp the phase motion itself, while the dissipation in superconducting layers works to damp relative motions of phase - differences.   their effects to hysteresis jumps are discussed.
images taken in 1.3  seeing show that a claimed hibernating nova, candidate 5 shown in a _ sky & telescope _ newswire item, is found to be a visual binary, with a 1.1  separation between components.   spectra reveal the components to be emission - line m0 and k7 stars.
we present the results on the photometric and spectroscopic monitoring of a luminous ap star hd103498.   the time - series photometric observations were carried out on 17 nights using three - channel fast photometer attached to the 1.04-m optical telescope at aries, nainital.   the photometric data of five nights of year 2007 show clear signature of 15-min periodicity.   however, the follow - up observations during 20072009 could not repeated any such periodicity. to confirm the photometric light variations,   the time - series spectroscopic observations were carried out with the 2.56-m nordic optical telescope ( not ) at la palma on february 2, 2009.   any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. model atmosphere and abundance analysis of hd103498 show that the star is evolved from the main sequence and its atmospheric abundances are similar to two other evolved ap stars hd133792 and hd204411 : large overabundances of si, cr, and fe and moderate overabundances of the rare - earth elements. these chemical properties and a higher effective temperature distinguish hd103498 from any known roap star.   stars : oscillations stars : variable stars : individual ( hd103498 ) stars : magnetic.
this work confirms that not only surface plasmons but many other kinds of electromagnetic eigenmodes should be considered in explaining the values of the transmittivity through a slab bearing a two - dimensional periodic corrugation. specifically,   the role of brewster - zennek modes appearing in metallic films exhibiting regions of weak positive dielectric constant.   it is proposed that these modes play a significant role in the light transmission in a thin chromium film perforated with normal cylindrical holes, for appropriate lattice parameters.
we targeted the massive star forming region w33a using the atacama large sub / millimeter array ( alma ) in band 6 ( 230 ghz ) and 7 ( 345 ghz ) to search for a sub@xmath01000au disc around the central o - type massive young stellar object ( myso ) w33a mm1-main.   our data achieves a resolution of @xmath10.2@xmath2 ( @xmath1500au ) and resolves the central core, mm1, into multiple components and reveals complex and filamentary structures.   there is strong molecular line emission covering the entire mm1 region.   the kinematic signatures are inconsistent with only keplerian rotation although we propose that the shift in the emission line centroids within @xmath11000au of mm1-main could hint at an underlying compact disc with keplerian rotation.   we can not however rule out the possibility of an unresolved binary or multiple system.   a putative smaller disc could be fed by the large scale spiral ` feeding filament'we detect in both gas and dust emission.   we also discuss the nature of the now - resolved continuum sources.       stars : formation - stars : protostars - stars : massive - techniques : interferometric - techniques : high angular resolution - submillimetre : stars
effects of young stellar clusters on their gas and dust environment are probed using mid - infrared ( mir ) wavelengths. the strong mir / ratios ( @xmath0 5 to 10 ) reveal the presence of current massive stars less than 5myr. using mir line ratios along with optical and nir data from the literature,   composite seds are constructed for ngc  1569, ngc  1140 and iizw40.   the stellar seds are then used as input to a dust model to study the impact of the hard, penetrating radiation field on the dust components, particularly in low metallicity environments, where the destructive effects of the massive stellar clusters on the environments occur on global scales.   for example, the smallest dust particles are destroyed over larger regions in the dwarf galaxies than in normal metallicity starbursts.
information visualization techniques are built on a context with many factors related to both vision and cognition, making it difficult to draw a clear picture of how data visually turns into comprehension. in the intent of promoting a better picture, here, we survey concepts on vision, cognition, and information visualization organized in a theorization named visual expression process.   our theorization organizes the basis of visualization techniques with a reduced level of complexity ; still, it is complete enough to foster discussions related to design and analytical tasks.   our work introduces the following contributions : ( 1 ) a theoretical compilation of vision, cognition, and information visualization ; ( 2 ) discussions supported by vast literature ; and ( 3 ) reflections on visual - cognitive aspects concerning use and design.   we expect our contributions will provide further clarification about how users and designers think about infovis, leveraging the potential of systems and techniques.   + * _ keywords _ * information visualization, infovis, vision science, cognitive science
we present a high spatial resolution map of the columnar electron temperature ( ) of a region to the south west of the trapezium in the orion nebula.   this map was derived from hubble space telescope images that isolated the primary lines of  for determination of the local extinction and of the  lines for determination of.   although there is no statistically significant variation of  with distance from the dominant ionizing star @xmath0  ori  c, we find small scale variations in the plane of the sky down to a few arcseconds that are compatible with the variations inferred from comparing the value of  derived from forbidden and recombination lines, commonly known as the @xmath1problem.   we present other evidence for fine scale variations in conditions in the nebula, these being variations in the surface brightness of the the nebula, fluctuations in radial velocities, and ionization changes. from our  map and other considerations   we estimate that @xmath1  @xmath2 for the orion nebula.   shadowed regions behind clumps close to the ionization front can make a significant contribution to the observed temperature fluctuations, but they can not account for the @xmath1  values inferred from several methods of temperature determination.   it is shown that an anomalous broadening of nebular emission lines appears to have the same sense of correlation as the temperature anomalies, although a causal link is not obvious.
we compute the coleman weinberg effective potential for the higgs field in rs gauge - higgs unification scenarios based on a bulk @xmath0 gauge symmetry, with gauge and fermion fields propagating in the bulk and a custodial symmetry protecting the generation of large corrections to the @xmath1 parameter and the coupling of the @xmath2 to the bottom quark.   we demonstrate that electroweak symmetry breaking may be realized, with proper generation of the top and bottom quark masses for the same region of bulk mass parameters that lead to good agreement with precision electroweak data in the presence of a light higgs.   we compute the higgs mass and demonstrate that for the range of parameters for which the higgs boson has standard model - like properties, the higgs mass is naturally in a range that varies between values close to the lep experimental limit and about 160 gev.   this mass range may be probed at the tevatron and at the lhc.   we analyze the kk spectrum and briefly discuss the phenomenology of the light resonances arising in our model.
the submillimetre common - user bolometer array ( scuba ) is a new continuum camera operating on the james clerk maxwell telescope ( jcmt ) on mauna kea, hawaii.   it consists of two arrays of bolometric detectors ; a 91 pixel 350/450 micron array and a 37 pixel 750/850 micron array.   both arrays can be used simultaneously and have a field - of - view of approximately 2.4 arcminutes in diameter on the sky.   ideally, performance should be limited solely by the photon noise from the sky background at all wavelengths of operation.   however, observations at submillimetre wavelengths are hampered by `` sky - noise '' which is caused by spatial and temporal fluctuations in the emissivity of the atmosphere above the telescope.   these variations occur in atmospheric cells that are larger than the array diameter, and so it is expected that the resultant noise will be correlated across the array and, possibly, at different wavelengths.    in this paper   we describe our initial investigations into the presence of sky - noise for all the scuba observing modes, and explain our current technique for removing it from the data.
in this paper we present the discussion on the salient points of the computational analysis that are at the basis of the paper _ rotation curves of galaxies by fourth order gravity _ @xcite.   in fact in this paper any galactic component ( bulge, disk and dark matter component ) required an onerous numerical computation since the gauss theorem is not applicable in the fourth order gravity.   the computational and data analysis have been made with the software mathematica@xmath0.
after a quick review of astrophysically relevant limits, i present a summary of mev scale tau neutrino mass limits derived from accelerator based experiments.   i argue that the current published limits appear to be too consistent, and that we therefore can not conclude that the tau neutrino mass limit is as low as usually claimed.   i provide motivational arguments calling into question the assumed statistical properties of the usual maximum likelihood estimators, and provide a prescription for deriving a more robust and understandable mass limit.
the evaluation of yukawa - enhanced two - loop contributions to the mssm higgs - boson mass is considered.   we prove the common assumption that regularization by dimensional reduction preserves supersymmetry at the required level. thus generating counterterms by multiplicative renormalization is correct.   technically, we identify a suitable slavnov - taylor identity, use a recently developed method to evaluate it at the two - loop level, and show that it is valid in dimensional reduction.   ippp/05/53 + dcpt/05/106 + mpp2005108 +    * mssm higgs - boson mass predictions and *   + * two - loop non - supersymmetric counterterms *   + wolfgang hollik@xmath0, dominik stckinger@xmath1   + _   @xmath2  max - planck - institut fr physik ( werner - heisenberg - institut ) + d-80805 munich, germany + @xmath3  institute for particle physics phenomenology, physics, + university of durham, durham dh1  3le, uk _
continuous  time quantum monte carlo ( ct - qmc ) method combined with dynamical mean field theory ( dmft ) is used to calculate both periodic anderson model ( pam ) and kondo lattice model ( klm ).   different parameter sets of both models are connected by the schrieffer  wolff transformation. for degeneracy @xmath0, a special particle   hole symmetric case of pam at half filling which always fixes one electron per impurity site is compared with the results of the klm.   we find a good mapping between pam and klm in the limit of large on  site hubbard interaction @xmath1 for different properties like self  energy, quasiparticle residue and susceptibility.   this allows us to extract quasiparticle mass renormalizations for the f electrons directly from klm.   the method is further applied to higher degenerate case and to realsitic heavy fermion system cerh@xmath2 in which the estimate of the sommerfeld coefficient is proven to be close to the experimental value.
capture cross section of magnetized particle ( with nonzero magnetic moment ) by braneworld black hole in uniform magnetic field is considered.   the magnetic moment of particle was chosen as it was done by @xcite and for the simplicity particle with zero electric charge is chosen.   it is shown that the spin of particle as well as the brane parameter are to sustain the stability of particles circularly orbiting around the black hole in braneworld i.e. spin of particles and brane parameter try to prevent the capture by black hole.
exact diagonalizations of the spin-1/2 heisenberg model on the checkerboard lattice have been performed for sizes up to @xmath0 in the full hilbert space and @xmath1 in the restricted subspace of first neighbor dimers.   this antiferromagnet does not break su(2 ) symmetry and displays long range order in 4-spin s=0 plaquettes. both the symmetry properties of the spectrum and various correlations functions are extensively studied. at variance with the kagom antiferromagnet,   the heisenberg quantum model on a checkerboard lattice is a valence bond crystal.   some results concerning the 3-dimensional spin-1/2 pyrochlore magnet ( for sizes 16 and 32 ) are also shown : this system could behave differently from its 2-dimensional analog.   ( ) +    pacs numbers : 75.10.jm ; 75.50.ee ; 75.40.-s
hard spheres interacting through a square - well potential were simulated using two different methods : brownian cluster dynamics ( bcd ) and event driven brownian dynamics ( edbd ).   the structure of the equilibrium states obtained by both methods were compared and found to be almost the identical.   self diffusion coefficients ( @xmath0 ) were determined as a function of the interaction strength.   the same values were found using bcd or edbd.   contrary the edbd, bcd allows one to study the effect of bond rigidity and hydrodynamic interaction within the clusters.   when the bonds are flexible the effect of attraction on @xmath0 is relatively weak compared to systems with rigid bonds.   @xmath0 increases first with increasing attraction strength, and then decreases for stronger interaction. introducing intra - cluster hydrodynamic interaction weakly increases @xmath0 for a given interaction strength.   introducing bond rigidity causes a strong decrease of @xmath0 which no longer shows a maximum as function of the attraction strength.
we present the results of the quest for ring - type structures on the maps observed by the planck satellite.   the results show that the vicinity of one radius ( @xmath0 radians ) of the rings is distinguished. twisting the circles into deformed ellipses   gives a pronounced drop of significance with the increase of twisting.   ring type structures in the planck map of the cmb + daniel an@xmath1, krzysztof a. meissner@xmath2 and pawe   nurowski@xmath3 + _ @xmath1science department suny maritime college, 6 pennyfield av.,   new york 10465, usa + @xmath4 faculty of physics, university of warsaw, pasteura 5, 02 - 093 warsaw, poland + @xmath5 center for theoretical physics of pas, al.   lotnikw 32/46, 02 - 688 warsaw, poland _
retrieval and content management are assumed to be mutually exclusive. in this paper   we suggest that they need not be so. in the usual information retrieval scenario, some information about queries leading to a website ( due to ` hits'or ` visits') is available to the server administrator of the concerned website.   this information can used to better present the content on the website.   further, we suggest that some more information can be shared by the retrieval system with the content provider. this will enable the content provider ( any website ) to have a more dynamic presentation of the content that is in tune with the query trends, without violating the privacy of the querying user.   the result will be a better synchronization between retrieval systems and content providers, with the purpose of improving the user s web search experience.   this will also give the content provider a say in this process, given that the content provider is the one who knows much more about the content than the retrieval system.   it also means that the content presentation may change in response to a query. in the end  , the user will be able to find the relevant content more easily and quickly.
seeing the earth crust as crisscrossed by faults filled with fluid at close to lithostatic pressures, we develop a model in which its elastic modulii are different in net tension versus compression. in constrast with standard nonlinear effects,   this `` threshold nonlinearity '' is non - perturbative and occurs for infinitesimal perturbations around the lithostatic pressure taken as the reference. for a given earthquake source  , such nonlinear elasticity is shown to ( i ) rotate, widen or narrow the different lobes of stress transfer, ( ii ) to modify the @xmath0 2d - decay of elastic stress green functions into the generalized power law @xmath1 where @xmath2 depends on the azimuth and on the amplitude of the modulii asymmetry. using reasonable estimates  , this implies an enhancement of the range of interaction between earthquakes by a factor up to @xmath3 at distances of several tens of rupture length.   this may explain certain long - range earthquake triggering and hydrological anomalies in wells and suggest to revisit the standard stress transfer calculations which use linear elasticity.   we also show that the standard double - couple of forces representing an earthquake source leads to an opening of the corresponding fault plane, which suggests a mechanism for the non - zero isotropic component of the seismic moment tensor observed for some events.   
persistent currents and drude weights are investigated for the tight - binding approximation to one - dimensional rings threaded by a magnetic flux and with potential given by some almost - periodic substitution sequences with different degrees of randomness, and for various potential strengths.   the drude weight @xmath0 distinguishes correctly conductors and insulators, in accordance with the results shown by the currents. in the case of insulators   the decay of @xmath1 for large ring lengths @xmath2 provides an estimate for the localization length of the system.   it is shown that the more random the sequence does not imply the smaller conducting properties.   this discrepancy between the hierarchy of disorder of the sequences and the capacity of conduction of the system is explained by the gaps in the energy spectra.   + pacs numbers : 73.23.ra, 73.20.dx, 73.23.-b
we present the combination of dynamical accretion model based on 3d grmhd simulations and general relativistic ( gr ) polarized radiative transfer.   we write down the formalism of and perform the gr ray - tracing of cyclo - synchrotron radiation through the model of accretion flow in sagittarius a*. gr polarimetric imaging is presented as well as the results for spectrum for a probable set of spins and orientations.   precise fitting formulae for faraday rotation and faraday conversion coefficients are employed for thermal plasma.   the axisymmetic flow pattern and the magnetic field geometry correspond to averaged 3d grmhd simulations near the black hole, whereas the analytic model was used far from the black hole.   the density scaling is found by fitting the sub - mm flux.   spin @xmath0 and inclination angle @xmath1 produce the best fit to sub - mm flux and linear polarization fraction.
we report on ccd photometry in the johnson @xmath0, @xmath1 and @xmath2 passbands for 146 stars in a @xmath3 region around the southern aggregate ngc  6994 ( c 2056 - 128 ), which appears in the lyng ( 1987 ) catalogue of open star clusters.   we argue that this object is not really an open cluster, but simply a random enhancement of four bright stars above the background level.   this stars sample includes hd  358033 and gsc  057780082, together with m  73, which is referred to as a binary or multiple star, but actually represents the whole asterism. since ngc  6994 is not the first case   ( see for instance carraro & patat 1995 ), this raises the possibility that other open clusters may have been misclassified.   we also suggest that ngc  6994 is unlikely to be an open cluster remnant ( ocr ).   open clusters and association : general  open cluster and associations : individual : ngc  6994  hertzsprung - russel ( hr ) diagram
the excitation of the electronic system induced by the adsorption of a hydrogen atom on the ( 111 ) surfaces of copper and silver is investigated using the time - dependent, mean - field newns - anderson model.   parameters for the model are obtained by fitting to density functional theory calculations, allowing the charge and energy transfer between adsorbate and surface to be calculated, together with the spectrum of electronic excitations.   these results are used to make direct comparisons with experimental measurements of chemicurrents, yielding good agreement for both the magnitude of the current and the ratio of the currents for h and d adsorption.   ,   ,    and    excitation spectra calculations, chemisorption, energy dissipation, electron - hole pairs 34.60.dy, 68.43.-h, 73.20.hb, 79.20.-m
x - ray observations of sn 1987a in the magellanic clouds have been performed throughout the rosat mission, using the pspc and the hri detectors.   we present the x - ray light curve based on all observations in the years 19911995. for the first time   a significant increase of the x - ray flux from sn 1987a can be seen, corresponding to x  ray luminosities ( 0.5 - 2 kev ) of @xmath0 about 4  8 years after the explosion.   sn 1987a is surrounded by a ringlike nebula, which is thought to form the interface between the blue  supergiant wind and the denser red  supergiant wind of the progenitor.   the x - ray data can constrain the density of the matter inside the ring to about @xmath1 and the date at which the blast wave will reach the ring to about ad 2003, when a dramatic brightening is expected to occur.   nevertheless, other interpretations of the x - ray emission are possible.   psfig.sty    _ _ _ _
we study theoretically poly - diacetylene chains diluted in their monomer matrix.   we employ the density - matrix renormalization group method ( dmrg ) on finite chains to calculate the ground state and low - lying excitations of the corresponding peierls   hubbard - ohno hamiltonian which is characterized by the electron transfer amplitude  @xmath0 between nearest neighbors, by the electron - phonon coupling constant  @xmath1, by the hubbard interaction  @xmath2, and by the long - range interaction  @xmath3.   we treat the lattice relaxation in the adiabatic limit, i.e., we calculate the polaronic lattice distortions for each excited state. using chains with up to 102  lattice sites  , we can safely perform the extrapolation to the thermodynamic limit for the ground - state energy and conformation, the single - particle gap, and the energies of the singlet exciton, the triplet ground state, and the optical excitation of the triplet ground state.   the corresponding gaps are known with high precision from experiment.   we determine a coherent parameter set @xmath4 from a fit of the experimental gap energies to the theoretical values which we obtain for 81  parameter points in the four dimensional search space @xmath5.   we identify dark in - gap states in the singlet and triplet sectors as seen in experiment. using a fairly stiff spring constant,   the length of our unit cell is about one percent larger than its experimental value.
we use molecular dynamics to study the nucleation of cracks in a two dimensional material without pre - existing cracks. we study models with zero and non - zero shear modulus. in both situations   the time required for crack formation obeys an arrhenius law, from which the energy barrier and pre - factor are extracted for different system sizes. for large systems, the characteristic time of rupture   is found to decrease with system size, in agreement with classical weibull theory. in the case of zero shear modulus,   the energy opposing rupture is identified with the breakage of a single atomic layer. in the case of non - zero shear modulus, thermally activated fracture   can only be studied within a reasonable time at very high strains. in this case   the energy barrier involves the stretching of bonds within several layers, accounting for a much higher barrier compared to the zero shear modulus case.   this barrier is understood within adiabatic simulations.
we study the consequences of noise and dissipation for parametric resonance during preheating.   the effective equations of motion for the inflaton and the radiation field are obtained and shown to present self - consistent noise and dissipation terms.   the equations exhibit the usual parametric resonance phenomenon, allowing for exponential amplification of the radiation modes inside the instability bands. by focusing on the dimension of the border of those bands   we explicitly show that they are fractal, indicating the strong dependence of the outcome in the initial conditions. the simultaneous effect of noise and dissipation to the fractality of the borders   are then examined.
the @xmath0-meson electromagnetic form - factors are calculated, both in a covariant and light - front frameworks with constituent quarks.   the effect of the breakdown of rotational symmetry for the one - body current operator in the null - plane is investigated by comparing calculations within light - front and covariant approaches.   this allows to choose the appropriate light - front prescription, among the several ones, to best evaluate the @xmath0-meson form - factors.    #
sink mobility is becoming popular due to excellent load balancing between nodes and ultimately resulting in prolonged network lifetime and throughput.   a major challenge is to provide reliable and energy - efficient operations are to be taken into consideration for different mobility patterns of sink.   aim of this paper is lifetime maximization of delay tolerant wireless sensor networks ( wsns ) through the manipulation of mobile sink ( ms ) on different trajectories.   we propose square routing protocol with ms ( srp - ms ) based on existing sep ( stable election protocol ) by making it cluster less ( cl ) and introducing sink mobility.   sink mobility ; trajectories ; wireless sensor network ; clusterless ; mobility pattern ; wsns
an alternative to the standard cold dark matter model has been recently proposed in which a significant fraction of the energy density of the universe is due to a dynamical scalar field ( @xmath0 ) whose effective equation - of - state differs from that of matter, radiation or cosmological constant ( @xmath1 ). in this paper, we determine how the @xmath0-component modifies the primordial inflation gravitational wave ( tensor metric ) contribution to the cosmic microwave background anisotropy and, thereby, one of the key tests of inflation.
a large time projection chamber ( tpc ) is the main device for tracking and charged - particle identification in the alice experiment at the cern lhc. after the second long shutdown in 2019 - 2020  , the lhc will deliver pb beams colliding at an interaction rate up to 50 khz, which is about a factor of 100 above the present read - out rate of the tpc. to fully exploit the lhc potential the tpc   will be upgraded based on the gas electron multiplier ( gem ) technology.   a prototype of an alice tpc outer read - out chamber ( oroc ) was equipped with twelve large - size gem foils as amplification stage to demonstrate the feasibility of replacing the current multi wire proportional chambers with the new technology. with a total area of @xmath00.76m@xmath1   it is the largest gem - based detector built to date.   the gem oroc was installed within a test field cage and commissioned with radioactive sources.   lhc, alice tpc, gem tpc, gas electron multiplier, continuous read - out
the transmission poles of @xmath0 number of identical dirac delta potentials placed periodically in one - dimension are examined in the complex - energy plane.   the numerical results show that the imaginary part of the poles scales with @xmath1.   an approximate form of the poles is derived which supports the scaling behaviour of the poles found numerically.   it is shown that the imaginary part of the poles are proportional to their real part for the poles close to the ends of the bands.
we apply random matrix theory to derive spectral density of large sample covariance matrices generated by multivariate @xmath0, @xmath1 and @xmath2 processes. in particular  , we consider a limit where the number of random variables @xmath3 and the number of consecutive time measurements @xmath4 are large but the ratio @xmath5 is fixed. in this regime   the underlying random matrices are asymptotically equivalent to free random variables ( frv ).   we apply the frv calculus to calculate the eigenvalue density of the sample covariance for several varma  type processes.   we explicitly solve the @xmath6 case and demonstrate a perfect agreement between the analytical result and the spectra obtained by monte carlo simulations.   the proposed method is purely algebraic and can be easily generalized to and.
we examine the maximal @xmath0 solution to the solar neutrino problem.   this solution can be motivated by the exact parity model and other theories.   the @xmath1 survival probability exhibits one of three qualitatively different behaviours depending on the value of @xmath2, viz.   approximately energy independent, just - so or msw. by the last of these we mean an enhanced night - time event rate due to regeneration in the earth.   we study all of these possibilities in the context of the recent superkamiokande data.
investigating long series of spectral and photometric observations, we found that the orbital elements of @xmath0  aur are subject to much larger uncertainties than usually believed.   the h@xmath1 emission is found to move basically with the f primary but its exact location should still be investigated.   we also find strong additional absorption and large reddening of the object near the third contact during the eclipse.   episodic atmospheric mass transfer from the f primary towards its companion is tentatively suggested.   = 0 = 99
we present the result of a systematic infrared 2.55  @xmath0 m spectroscopic study of 22 nearby infrared galaxies over a wide infrared luminosity range ( @xmath1 ) obtained from _ akari _ infrared camera ( irc ). the unique band of the _ akari _ irc spectroscopy enables us to access both the 3.3  @xmath0 m polycyclic aromatic hydrocarbon ( pah ) emission feature from star forming activity and the continuum of torus - dust emission heated by an active galactic nucleus ( agn ).   applying our agn diagnostics to the _ akari _ spectra, we discover 14 buried agns.   the large fraction of buried agns suggests that agn activity behind the dust is almost ubiquitous in ultra-/luminous infrared galaxies ( u / lirgs ).   we also find that both the fraction and energy contribution of buried agns increase with infrared luminosity from @xmath2 to @xmath3, including normal infrared galaxies with @xmath4.   the energy contribution from agns in the total infrared luminosity is only @xmath5 7% in lirgs and @xmath5  20% in ulirgs, suggesting that the majority of the infrared luminosity originates from starburst activity. using the pah emission  , we investigate the luminosity relation between star formation and agn.   we find that these infrared galaxies exhibit higher star formation rates than optically selected seyfert galaxies with the same agn luminosities, implying that infrared galaxies could be an early evolutionary phase of agn.
model quantum hall states including laughlin, moore - read and read - rezayi states are generalized into appropriate anisotropic form.   the generalized states are exact zero - energy eigenstates of corresponding _ anisotropic _ two- or multi - body hamiltonians, and explicitly illustrate the existence of geometric degrees of in the fractional quantum hall effect. these generalized model quantum hall states can provide a good description of the quantum hall system with anisotropic interactions.   some numeric results of these anisotropic quantum hall states are also presented.
we present our optical observations of _ swift _ grb 070518 afterglow obtained at the 0.8-m tsinghua university - national astronomical observatory of china telescope ( tnt ) at xinglong observatory.   our follow - up observations were performed from 512 sec after the burst trigger. with the upper limit of redshift@xmath00.7, grb 070518   is found to be an optically dim burst.   the spectra indices @xmath1 of optical to x - ray are slightly larger than 0.5, which implies the burst might be a dark burst.   the extinction @xmath2 of the host galaxy is 3.2 mag inferred from the x - ray hydrogen column density with galactic extinction law, and 0.3 mag with smc extinction law.   also, it is similar to three other low - redshift optically dim bursts, which belong to xrr or xrf, and mid - term duration(@xmath3, except for grb 070419a, @xmath4=116s ).   moreover, its @xmath5 band afterglow flux is well fitted by a single power - law with an index of 0.87.   the optical afterglow and the x - ray afterglow in the normal segment might have the same mechanism, as they are consistent with the prediction of the classical external shock model. besides, grb 070518 agrees with amati relation under reasonable assumptions.   the ghirlanda relation is also tested with the burst.       gamma rays : bursts  gamma rays : observations  individual : grb 070518.
we introduce a new method of storing visual information in quantum mechanical systems which has certain advantages over more restricted classical memory devices.   to do this we employ uniquely quantum mechanical properties such as entanglement in order to store information concerning the position and shape of simple objects.
in general, homeowners refinance in response to a decrease in interest rates, as their borrowing costs are lowered. however, it is worth investigating the effects of refinancing after taking the underlying costs into consideration.   here we develop a synthetic mortgage calculator that sufficiently accounts for such costs and the implications on new monthly payments. to confirm the accuracy of the calculator  , we simulate the effects of refinancing over 15 and 30 year periods.   we then model the effects of refinancing as risk to the issuer of the mortgage, as there is negative duration associated with shifts in the interest rate.   furthermore, we investigate the effects on the swap market as well as the treasury bond market.   we model stochastic interest rates using the vasicek model.
we derive equations for the quasiclassical green s functions @xmath0 within a simple model of a two - band superconductor with a spin - density - wave ( sdw ).   the elements of the matrix @xmath0 are the retarded, advanced, and keldysh functions each of which is an @xmath1 matrix in the gorkov - nambu, the spin and the band space. in equilibrium, these equations are a generalization of the eilenberger equation. on the basis of the derived equations we analyze the knight shift, the proximity and the dc josephson effects in the superconductors under consideration.   the knight shift is shown to depend on the orientation of the external magnetic field with respect to the direction of the vector of the magnetization of the sdw.   the proximity effect is analyzed for an interface between a superconductor with the sdw and a normal metal.   the function describing both superconducting and magnetic correlations is shown to penetrate the normal metal or a metal with the sdw due to the proximity effect.   the dc josephson current in an @xmath2 junction is also calculated as a function of the phase difference @xmath3.   it is shown that in our model the josephson current does not depend on the mutual orientation of the magnetic moments in the superconductors @xmath4 and is proportional to  @xmath5.   the dissipationless spin current @xmath6 depends on the angle @xmath7 between the magnetization vectors in the same way ( @xmath8 ) and is not zero above the superconducting transition temperature.
in this work we use models of molecular clouds ( mc ), and non - lte radiative transfer calculations, to obtain a theoretical calibration of the relation between lte @xmath0co column density and true column density in mcs.   the cloud models consist of 3 dimensional grids of density and velocity fields obtained as solutions of the compressible magneto - hydrodynamic equations in a 128@xmath1 periodic grid in both the supersonic and super - alfvnic regimes. due to the random nature of the velocity field and the presence of shocks,   the density spans a continuous range of values covering over 5 - 6 orders of magnitude ( from @xmath20.1 to @xmath210@xmath3 @xmath4 ). as a result  , the lte column density can be calibrated over 3 orders of magnitude.   we find that lte column density of molecular clouds typically underestimates the mean @xmath0co true column density by a factor ranging from 1.3 to 7.   these results imply that the standard lte methods for the derivation of column densities from co data systematically underestimate the true values independent of other major sources of uncertainty such as the relative abundance of co.    epsf
particle - in - cell ( pic ) simulation is often impractical for the same reason that it is powerful : it includes too much physics. sometimes the mere ability to simulate physics on small length or time scales requires those scales to be resolved ( by the cell size and timestep ) to avoid instability, even when the effects at those scales contribute negligibly to the phenomenon motivating the simulation.   for example, a timestep larger than the inverse plasma frequency will often result in unphysical growth of plasma oscillations, even in simulations where plasma oscillations should not arise at all.   larger timesteps are possible in simulations based on reduced physics models, such as mhd or gyrokinetics, or in simulations with implicit time - advances. a new method, speed - limited pic ( slpic ) simulation, allows larger timesteps without reduced physics and with an explicit time - advance.   the slpic method slows down fast particles while still accurately representing the particle distribution.   slpic is valid when fields and distribution functions change slowly compared with the desired timestep ; slpic is useful when that timestep is much larger than that allowed by standard pic ( and when alternative approximations do not include enough physics ).   speed - limited pic can be implemented with relatively localized modifications of a standard pic code.   simulation, fdtd, pic, finite difference time domain, particle - in - cell, speed - limited particle - in - cell
a field of 1.013 ster in the rosat all - sky survey ( rass ), centered on the south galactic pole ( sgp ), has been searched in a systematic, objective manner for clusters of galaxies.   the procedure relied on a correlation of the x - ray positions and properties of rosat sources in the field with the distribution of galaxies in the cosmos digitised data base, which was obtained from scanning the plates of the uk schmidt iiia - j optical survey of the southern sky.   the study used the second rosat survey data base ( rass-2 ) and included several optical observing campaigns to measure cluster redshifts.   the search, which is a precursor to the larger reflex survey encompassing the whole southern sky, reached the detection limits of both the rass and the cosmos data, and yielded a catalog of 186 clusters in which the lowest flux is @xmath0 in the @xmath1 band.   of these 157 have measured redshifts. using a flux limit of @xmath2   a complete subset of 112 clusters was obtained, of which 110 have measured redshifts.   the spatial distribution of the x - ray clusters out to a redshift of @xmath3 shows an extension of the local supercluster to the pisces - cetus supercluster @xmath4, and an orthogonal structure at higher redshift @xmath5.   this result is consistent with large - scale structure suggested by optical surveys.
the results on the vertical distribution of optical turbulence above the five mountains which were investigated by the site testing for the thirty meter telescope ( tmt ) are reported.   on san pedro mrtir in mexico, the 13 north site on mauna kea and three mountains in northern chile cerro tolar, cerro armazones and cerro tolonchar, mass - dimm turbulence profilers have been operated over at least two years.   acoustic turbulence profilers  sodars  were also operated at these sites.   the obtained turbulence profiles indicate that at all sites the lowest 200  m are the main source of the total seeing observed, with the chilean sites showing a weaker ground layer than the other two sites.   the two northern hemisphere sites have weaker turbulence at altitudes above 500  m, with 13n showing the weakest 16  km turbulence, being responsible for the large isoplanatic angle at this site.   the influence of the jetstream and wind speeds close to the ground on the clear sky turbulence strength throughout the atmosphere are discussed, as well as seasonal and nocturnal variations.   this is the sixth article in a series discussing the tmt site testing project.
we propose a hole decomposition scheme to exactly solve a class of spin-1 quantum ising models with transverse or longitudinal single - ion anisotropy. in this scheme  , the spin-1 model is mapped onto a family of the @xmath0 transverse ising models, characterized by the total number of holes.   a recursion formula is derived for the partition function based on the reduced @xmath0 ising model.   this simplifies greatly the summation over all the hole configurations.   it allows the thermodynamic quantities to be rigorously determined in the thermodynamic limit.   the ground state phase diagram is determined for both the uniform and dimerized spin chains.   the corresponding thermodynamic properties are calculated and discussed.
the understanding of nonlinear @xmath0-symmetric quantum systems, arising for example in the theory of bose - einstein condensates in @xmath0-symmetric potentials, is widely based on numerical investigations, and little is known about generic features induced by the interplay of @xmath0-symmetry and nonlinearity. to gain deeper insights it is important to have analytically solvable toy - models at hand. in the present paper   the stationary states of a simple toy - model of a @xmath0-symmetric system are investigated.   the model can be interpreted as a simple description of a bose - einstein condensate in a @xmath0-symmetric double well trap in a two - mode approximation.   the eigenvalues and eigenstates of the system can be explicitly calculated in a straight forward manner ; the resulting structures resemble those that have recently been found numerically for a more realistic @xmath0-symmetric double delta potential.   in addition, a continuation of the system is introduced that allows an interpretation in terms of a simple linear matrix model.
we perform first - principles calculations of electronic structure and optical properties for uo@xmath0 and puo@xmath0 based on the density functional theory using the generalized gradient approximation ( gga)+__u _ _ scheme.   the main features in orbital - resolved partial density of states for occupied _ f _ and _ p _ orbitals, unoccupied _ d _ orbitals, and related gaps are well reproduced compared to experimental observations. based on the satisfactory ground - state electronic structure calculations, the dynamical dielectric function and related optical spectra, i.e., the reflectivity, adsorption coefficient, energy - loss, and refractive index spectrum, are obtained.   these results are consistent well with the attainable experiments.
discs of dusty debris around main - sequence stars indicate fragmentation of orbiting planetesimals, and for a few a - type stars, a gas component is also seen that may come from collisionally - released volatiles. here   we find the sixth example of a co - hosting disc, around the @xmath030 myr - old a0-star hd 32997.   two more of these co - hosting stars, hd 21997 and 49 cet, have also been imaged in dust with scuba-2 within the sons project.   a census of 27 a - type debris hosts within 125 pc now shows 7/16 detections of carbon - bearing gas within the 5 - 50 myr epoch, with no detections in 11 older systems.   such a prolonged period of high fragmentation rates corresponds quite well to the epoch when most of the earth was assembled from planetesimal collisions.   recent models propose that collisional products can be spatially asymmetric if they originate at one location in the disc, with co particularly exhibiting this behaviour as it can photodissociate in less than an orbital period.   of the six co - hosting systems, only @xmath1 pic is in clear support of this hypothesis.   however, radiative transfer modelling with the prodimo code shows that the co is also hard to explain in a proto - planetary disc context.       planetary systems   circumstellar matter  infrared : stars
we present a 5-phase equation of state ( eos ) for elemental carbon.   the phases considered are : diamond, bc8, simple - cubic, simple - hexagonal, and the liquid / plasma state. the solid phase free energies are constrained by density functional theory ( dft ) calculations.   vibrational contributions to the free energy of each solid phase are treated within the quasiharmonic framework.   the liquid free energy model is constrained by fitting to a combination of dft molecular dynamics performed over the range 10,000 k @xmath0 100,000 k, and path integral quantum monte carlo calculations for @xmath1 100,000 k ( both for @xmath2 between 3 and 12 g / cc, with select higher-@xmath2 dft calculations as well ).   the liquid free energy model includes an atom - in - jellium approach to account for the effects of ionization due to temperature and pressure in the plasma state, and an ion - thermal model which includes the approach to the ideal gas limit. the precise manner in which the ideal gas limit is reached   is greatly constrained by both the highest temperature dft data and the path integral data, forcing us to discard an ion - thermal model we had used previously in favor of a new one.   predictions are made for the principal hugoniot and the room - temperature isotherm, and comparisons are made to recent experimental results.
it has been shown recently that dirac operators satisfying the ginsparg - wilson relation provide a solution of the chirality problem in qcd at finite lattice spacing.   we discuss different ways to construct these operators and their properties.   the possibility to define lattice chiral gauge theories is briefly discussed as well.
we consider various 2d lattice equations and their integrability, from the point of view of 3d consistency, lax pairs and bcklund transformations. we show that these concepts, which are associated with integrability, are not strictly equivalent. in the course of our analysis  , we introduce a number of black and white lattice models, as well as variants of the functional yang - baxter equation.
geomagnetism is characterized by intermittent polarity reversals and rapid fluctuations.   we have recently proposed a coupled macro - spin model to describe these dynamics based on the idea that the whole dynamo mechanism is described by the coherent interactions of many small dynamo elements. in this paper  , we further develop this idea and construct a minimal model for magnetic variations.   this simple model naturally yields many of the observed features of geomagnetism : its time evolution, the power spectrum, the frequency distribution of stable polarity periods, etc.   this model has coexistent two phases ; i.e. the cluster phase which determines the global dipole magnetic moment and the expanded phase which gives random perpetual perturbations that yield intermittent polarity flip of the dipole moment.   this model can also describe the synchronization of the spin oscillation.   this corresponds to the case of sun and the model well describes the quasi - regular cycles of the solar magnetism.   furthermore, by analyzing the relevant terms of mhd equation based on our model, we have obtained a scaling relation for the magnetism for planets, satellites, sun, and stars. comparing it with various observations  , we can estimate the scale of the macro - spins.
we explore the warm molecular and ionized gas in the centers of two megamaser disk galaxies using @xmath0band spectroscopy.   our ultimate goal is to determine how gas is funneled onto the accretion disk, here traced by megamaser spots on sub - pc scales.   we present nir ifu data with a resolution of @xmath1 pc for two galaxies : ngc 4388 with vlt / sinfoni and ngc 1194 with keck / osiris+ao.   the high spatial resolution and rich spectral diagnostics allow us to study both the stellar and gas kinematics as well as gas excitation on scales only an order of magnitude larger than the maser disk.   we find a drop in the stellar velocity dispersion in the inner @xmath2 pc of ngc 4388, a common signature of a dynamically cold central component seen in many active nuclei.   we also see evidence for non - circular gas motions in the molecular hydrogen on similar scales, with the gas kinematics on 100-pc scales aligned with the megamaser disk.   in contrast, the high ionization lines and br@xmath3  trace outflow along the 100 pc - scale jet. in ngc 1194,   the continuum from the accreting black hole is very strong, making it difficult to measure robust two - dimensional kinematics, but the spatial distribution and line ratios of the molecular hydrogen and br@xmath3 have consistent properties between the two galaxies.
we extend our spiral galaxy models that successfully describe nearby template spectra as well as the redshift evolution of cfrs and hdf spirals to include  in a chemically consistent way  the redshift evolution of a series of individual elements.   comparison with observed dla abundances shows that dlas might well be the progenitors of present - day spiral types sa through sd.   our models bridge the gap between high redshift dla and nearby spiral hii region abundances.   the slow redshift evolution of dla abundances is a natural consequence of the long sf timescales for disks, the scatter at any redshift reflects the range of sf timescales from early to late spiral types.   we claim that while at high redshift all spiral progenitor types seem to give rise to dla absorption, towards low redshifts, the early type spirals seem to drop out of dla samples due to low gas and/or high metal and dust content.   model implications for the spectrophotometric properties of the dla galaxy population are discussed in the context of campaigns for the optical identifications of dla galaxies both at low and high redshift.
we investigate the collective aspects of rydberg excitation in ultracold mesoscopic systems.   strong interactions between rydberg atoms influence the excitation process and impose correlations between excited atoms.   the manifestations of the collective behavior of rydberg excitation are the many - body rabi oscillations, spatial correlations between atoms as well as the fluctuations of the number of excited atoms.   we study these phenomena in detail by numerically solving the many - body schrdinger equation.
we have measured the performances of a lyso crystal matrix prototype tested with electron and photon beams in the energy range 60@xmath0450 mev.   this study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the mu2e experiment.   calorimetry, scintillating crystals, avalanche photodiodes    29.40.mc, 29.40.vj
it is well known, and easy to see, that not each nondeterministic bchi automaton on infinite words can be simulated by a nondeterministic co - bchi automaton.   we show that in the cases when such a simulation is possible, the number of states needed for it can grow nonlinearly.   more precisely, we show a sequence of  as we believe, simple and elegant  languages which witness the existence of a nondeterministic bchi automaton with @xmath0 states, which can be simulated by a nondeterministic co - bchi automaton, but can not be simulated by any nondeterministic co - bchi automaton with less than @xmath1 states for some constant @xmath2.   this improves on the best previously known lower bound of @xmath3.
we characterise the eigenfunctions of an equilateral triangle billiard in terms of its nodal domains.   the number of nodal domains has a quadratic form in terms of the quantum numbers, with a non - trivial number - theoretic factor.   the patterns of the eigenfunctions follow a group - theoretic connection in a way that makes them predictable as one goes from one state to another.   extensive numerical investigations bring out the distribution functions of the mode number and signed areas.   the statistics of the boundary intersections is also treated analytically.   finally, the distribution functions of the nodal loop count and the nodal counting function are shown to contain information about the classical periodic orbits using the semiclassical trace formula.   we believe that the results belong generically to non - separable systems, thus extending the previous works which are concentrated on separable and chaotic systems.
we present time - resolved photoluminescence measurements on two series of oligo-_p_-phenylenevinylene materials that self - assemble into supramolecular nanostructures with thermotropic reversibility in dodecane.   one set of derivatives form chiral, helical stacks while the second set form less organised, ` frustrated'stacks. here   we study the effects of supramolecular organisation on the resonance energy transfer rates.   we measure these rates in nanoassemblies formed with mixed blends of oligomers and compare them with the rates predicted by frster theory.   our results and analysis show that control of supramolecular order in the nanometre lengthscale has a dominant effect on the efficiency and dimensionality of resonance energy transfer.
we study the dynamical behavior of a square lattice ising model with exchange and dipolar interactions by means of monte carlo simulations.   after a sudden quench to low temperatures we find that the system may undergo a coarsening process where stripe phases with different orientations compete or alternatively it can relax initially to a metastable nematic phase and then decay to the equilibrium stripe phase through nucleation.   we measure the distribution of equilibration times for both processes and compute their relative probability of occurrence as a function of temperature and system size.   this peculiar relaxation mechanism is due to the strong metastability of the nematic phase, which goes deep in the low temperature stripe phase.   we also measure quasi - equilibrium autocorrelations in a wide range of temperatures.   they show a distinct decay to a plateau that we identify as due to a finite fraction of frozen spins in the nematic phase.   we find indications that the plateau is a finite size effect.   relaxation times as a function of temperature in the metastable region show super - arrhenius behavior, suggesting a possible glassy behavior of the system at low temperatures.
direct searches for low mass dark matter particles via scattering off target nuclei require detection of recoiling atoms with energies of @xmath0  kev or less.   the amount of electronic excitation produced by such atoms is quenched relative to a recoiling electron of the same energy.   the lindhard model of this quenching, as originally formulated, remains widely used after more than 50 years.   the present work shows that for very small energies, a simplifying approximation of that model must be removed.   implications for the sensitivity of direct detection experiments are discussed.
magnetic flux in mesoscopic rings under the quantum smoluchowski regime is investigated.   quantum corrections to the dissipative current are shown to form multistable steady states and can result in statistical enhancement of the magnetic flux.   the relevance of quantum correction effects is supported via the entropic criterion.   a possible application for a qutrit architecture of quantum information is proposed.
we present new spectroscopic observations of the early type, double - lined eclipsing binary v446cep.   the radial velocities and the photometric data obtained by @xmath0 were analysed for deriving the astrophysical parameters of the components.   masses and radii were determined as m@xmath1=17.94@xmath21.16 m@xmath3 and r@xmath1=8.33@xmath20.29 r@xmath3, m@xmath4=2.64@xmath20.30 m@xmath3 and r@xmath4=2.13@xmath20.10 r@xmath3 for the components of v446cep.   our analyses show that v446cep is a detached algol - type system. based on the position of the components plotted on the theoretical hertzsprung - russell diagram  , we estimate that the age of v446cep is about 10 myr, neglecting the effects of mass - loss and mass exchange between the components. using the ubvjhk magnitudes and interstellar absorption we estimated the mean distance to the system v446cep as 1100@xmath262pc.   stars : binaries : eclipsing  stars : fundamental parameters  stars : binaries : spectroscopic  stars : v446cep
we use 3d radiative mhd simulations to investigate the formation and dynamics of small - scale ( less than 0.5  mm in diameter ) vortex tubes spontaneously generated by turbulent convection in quiet - sun regions with initially weak mean magnetic fields.   the results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere.   the vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong ( near sonic ) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and which attain magnetic field strengths ranging from 200  g in the chromosphere to more than 1  kg in the photosphere.   we investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the convection zone into the chromosphere.
more than @xmath0 deviations from the standard model are observed in the angular observable @xmath1 of @xmath2 and muon @xmath3 ; also, a new resonance with a mass of 750 gev is indicated by atlas and cms. to resolve these anomalies,   we extend the standard model by adding one higgs singlet and two leptoqaurks.   it is found that the signal strength of the diphoton higgs decay can have a significant deviation from unity and is within the data errors.   although @xmath4 put severe bounds on some couplings, it is found that the excesses of @xmath1 and muon @xmath3 can still be explained and can be accommodated to the measurement of @xmath5 in this model.   the large cross section for producing the 750 gev higgs singlet and decaying to diphoton can be achieved when the trilinear couplings of higgs singlet to leptoquarks are of @xmath6 tev and leptoquark mass @xmath7 tev.   kias - p16051
recent experiments by kiritani _ et al.   _ @xcite have revealed a surprisingly high rate of vacancy production during high - speed deformation of thin foils of fcc metals.   virtually no dislocations are seen after the deformation.   this is interpreted as evidence for a dislocation - free deformation mechanism at very high strain rates.   we have used molecular - dynamics simulations to investigate high - speed deformation of copper crystals.   even though no pre - existing dislocation sources are present in the initial system, dislocations are quickly nucleated and a very high dislocation density is reached during the deformation.    due to the high density of dislocations,   many inelastic interactions occur between dislocations, resulting in the generation of vacancies. after the deformation  , a very high density of vacancies is observed, in agreement with the experimental observations.   the processes responsible for the generation of vacancies are investigated.   the main process is found to be incomplete annihilation of segments of edge dislocations on adjacent slip planes.   the dislocations are also seen to be participating in complicated dislocation reactions, where sessile dislocation segments are constantly formed and destroyed.
we prove an inequality between horizon area and angular momentum for a class of axially symmetric black holes.   this class includes initial conditions with an isometry which leaves fixed a two - surface.   these initial conditions have been extensively used in the numerical evolution of rotating black holes.   they can describe highly distorted black holes, not necessarily near equilibrium.   we also prove the inequality on extreme throat initial data, extending previous results.
we demonstrate that the formation of collapsing cores in subcritical clouds is accelerated by nonlinear flows, by performing three - dimensional non - ideal mhd simulations.   an initial random supersonic ( and trans - alfvnic ) turbulent - like flow is input into a self - gravitating gas layer that is threaded by a uniform magnetic field ( perpendicular to the layer ) such that the initial mass - to - flux ratio is subcritical.   magnetic ambipolar diffusion occurs very rapidly initially due to the sharp gradients introduced by the turbulent flow.   it subsequently occurs more slowly in the traditional near - quasistatic manner, but in regions of greater mean density than present in the initial state.   the overall timescale for runaway growth of the first core(s ) is several @xmath0 yr, even though previous studies have found a timescale of several @xmath1 yr when starting with linear perturbations and similar physical parameters.   large - scale supersonic flows exist in the cloud and provide an observationally testable distinguishing characteristic from core formation due to linear initial perturbations.   however, the nonlinear flows have decayed sufficiently that the relative infall motions onto the first core are subsonic, as in the case of starting from linear initial perturbations.   the ion infall motions are very similar to those of neutrals ; however, they lag the neutral infall in directions perpendicular to the mean magnetic field direction and lead the neutral infall in the direction parallel to the mean magnetic field.
there is now strong observational evidence that the expansion of the universe is accelerating.   the standard explanation invokes an unknown `` dark energy '' component.   but such scenarios are faced with serious theoretical problems, which has led to increased interest in models where instead general relativity is modified in a way that leads to the observed accelerated expansion.   the question then arises whether the two scenarios can be distinguished. here   we show that this may not be so easy, demonstrating explicitely that a generalised dark energy model can match the growth rate of the dgp model and reproduce the 3 + 1 dimensional metric perturbations.   cosmological observations are then unable to distinguish the two cases.
we investigate bose - einstein condensation for interacting bosons at zero and nonzero temperature.   functional renormalization provides us with a consistent method to compute the effect of fluctuations beyond the bogoliubov approximation. for three - dimensional dilute gases  , we find an upper bound on the scattering length @xmath0 which is of the order of the microphysical scale - typically the range of the van der waals interaction.   in contrast to fermions near the unitary bound, no strong interactions occur for bosons with approximately pointlike interactions, thus explaining the high quantitative reliability of perturbation theory for most quantities. for zero temperature   we compute the quantum phase diagram for bosonic quasiparticles with a general dispersion relation, corresponding to an inverse microphysical propagator with terms linear and quadratic in the frequency.   we compute the temperature dependence of the condensate and particle density @xmath1, and find for the critical temperature @xmath2 a deviation from the free theory, @xmath3. for the sound velocity at zero temperature   we find very good agreement with the bogoliubov result, such that it may be used to determine the particle density accurately.
recent studies attracted the attention on the inherent structure landscape ( isl ) approach as a reduced description of proteins allowing to map their full thermodynamic properties.   however, the analysis has been so far limited to a single topology of a two - state folding protein, and the simplifying assumptions of the method have not been examined. in this work,   we construct the thermodynamics of four two - state folding proteins of different sizes and secondary structure by md simulations using the isl method, and critically examine possible limitations of the method.   our results show that the isl approach correctly describes the thermodynamics function, such as the specific heat, on a qualitative level. using both analytical and numerical methods,   we show that some quantitative limitations can not be overcome with enhanced sampling or the inclusion of harmonic corrections.
we propose a parallel adaptive constraint - tightening approach to solve a linear model predictive control problem for discrete - time systems, based on inexact numerical optimization algorithms and operator splitting methods.   the underlying algorithm first splits the original problem in as many independent subproblems as the length of the prediction horizon.   then, our algorithm computes a solution for these subproblems in parallel by exploiting auxiliary tightened subproblems in order to certify the control law in terms of suboptimality and recursive feasibility, along with closed - loop stability of the controlled system. compared to prior approaches based on constraint tightening, our algorithm computes the tightening parameter for each subproblem to handle the propagation of errors introduced by the parallelization of the original problem.   our simulations show the computational benefits of the parallelization with positive impacts on performance and numerical conditioning when compared with a recent nonparallel adaptive tightening scheme.
the quantum renormalization group method is applied to study the quantum criticality and entanglement entropy of the ground state of the ising chain in the presence of antisymmetric anisotropic couplings and alternating exchange interactions.   the quantum phase transitions can be characterized by the discontinuity in the second derivative of the energy of renormalized ground state.   the phase diagram is obtained by the critical boundary line.   the first derivative of entanglement entropy also diverges at the same critical points after enough iterations of the renormalization of coupling constants.   the antisymmetric anisotropy and alternating interaction can enhance the renormalized entanglement via the creation of quantum fluctuations.   the scaling behavior of the derivative of the entropy around the critical points manifest the logarithm dependence on the size of the spin system.   pacs : 03.67.mn, 03.65.ud, 75.10.pq, 73.43.nq
an algorithm for exact maximum likelihood(ml ) decoding on tail - biting trellises is presented, which exhibits very good average case behavior.   an approximate variant is proposed, whose simulated performance is observed to be virtually indistinguishable from the exact one at all values of signal to noise ratio, and which effectively performs computations equivalent to at most two rounds on the tail - biting trellis.   the approximate algorithm is analyzed, and the conditions under which its output is different from the ml output are deduced.   the results of simulations on an awgn channel for the exact and approximate algorithms on the 16 state tail - biting trellis for the ( 24,12 ) extended golay code, and tail - biting trellises for two rate 1/2 convolutional codes with memories of 4 and 6 respectively, are reported.   an advantage of our algorithms is that they do not suffer from the effects of limit cycles or the presence of pseudocodewords.              
we uncover a remarkable role that an infinite hierarchy of non  linear differential equations plays in organizing and connecting certain @xmath0 string theories non  perturbatively.   we are able to embed the type 0a and 0b @xmath1 minimal string theories into this single framework.   the string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy.   we observe that there are several other string  like limits of the system, and conjecture that some of them are type  iia and  iib @xmath2 minimal string backgrounds.   we explain how these and several string  like special points arise and are connected. in some cases, the framework endows the theories with a non  perturbative definition for the first time.   notably, we discover that the painlev iv equation plays a key role in organizing the string theory physics, joining its siblings, painlev i and ii, whose roles have previously been identified in this minimal string context.    * string theory and water waves *    * ramakrishnan iyer@xmath3, clifford v. johnson@xmath4, jeffrey s. pennington@xmath5 *    _ @xmath6department of physics and astronomy _    _ university of southern california _    _ los angeles, ca 90089 - 0484, u.s.a. _    _ @xmath5slac national accelerator laboratory _    _ stanford university _    _ stanford, ca 94309, u.s.a. _    @xmath3ramaiyer, @xmath4johnson1,  usc.edu ; @xmath5jpennin  stanford.edu
* beyond the use of genuine monolithic integrated optical platforms, we report here a hybrid strategy enabling on - chip generation of configurable heralded two - photon states.   more specifically, we combine two different fabrication techniques, _   i.e. _, non - linear waveguides on lithium niobate for efficient photon - pair generation and femtosecond - laser - direct - written waveguides on glass for photon manipulation. through real - time device manipulation capabilities,   a variety of path - coded heralded two - photon states can be produced, ranging from product to entangled states.   those states are engineered with high levels of purity, assessed by fidelities of 99.5@xmath08% and 95.0@xmath08%, respectively, obtained via quantum interferometric measurements.   our strategy therefore stands as a milestone for further exploiting entanglement - based protocols, relying on engineered quantum states, and enabled by scalable and compatible photonic circuits. *
quantum walks have been very useful in developing search algorithms in quantum information, in particular for devising of spatial search algorithms.   however, the construction of continuous - time quantum search algorithms in two - dimensional lattices has proved difficult, requiring additional degrees of freedom. here  , we demonstrate that continuous - time quantum walk search is possible in two - dimensions by changing the search topology to a graphene lattice, utilising the dirac point in the energy spectrum.   this is made possible by making a change to standard methods of marking a particular site in the lattice.   various ways of marking a site are shown to result in successful search protocols.   we further establish that the search can be adapted to transfer probability amplitude across the lattice between specific lattice sites thus establishing a line of communication between these sites.
new experiment arrangement to study the spin rotation and oscillation of particles of a gas target, through which a beam of high energy particles passes, is discussed. such experiment arrangement   make it realizable for a storage ring and allows one to study the zero - angle scattering amplitude at the highest possible energies.   life - time of a particle beam in a storage ring can reach several hours and even days.   life - time of a particle in a gas target ( gas trap ) is long too.   particles circulate in the storage ring with the frequency @xmath0 of several mhz.   this yields to the @xmath0-fold increase of the density of the beam of high energy particles, which blows a gas trap, in comparison with the single - pass case.   finally, this causes the perfectly acceptable angle of the spin rotation of particles containing in the gas cell.   relation between the index of refraction and effective potential energy of a particle in a medium is discussed.   phenomenon of the spin rotation of a particle captured to a trap under the action of a beam of polarized particles is considered.   expressions for effective potential energy and angle of spin rotation are derived for particles in a trap.   rotation and oscillation of deuteron spin is studied.   estimations for angle of rotation show that the effect can be experimentally observed.
the earliest results of cms exhibit central pseudo rapidity densities larger than the predictions of the different models. introducing on this basis new guidelines with larger multiplicities of secondaries in the models implemented in the simulations,   we examine the consequences in @xmath0 ray families ( spikes in rapidity distribution, coplanar emission ) and very large eas ( penetration power in the atmosphere ).
recent results from the hess gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above @xmath00.4 tev and discrete sources in and near the galactic centre.   here, we put forward a possible explanation in terms of the diffusion of cosmic ray protons from a succession of supernova remnants (  snr  ) in the sgra * region of the galaxy plus a contribution from snr in the rest of the galactic centre region, to be called the galactic centre ridge (  gcr  ).   protons are favoured over electrons because the @xmath1 magnetic fields in the region will attenuate energetic electrons severely.   prominent features are the need for anomalous diffusion of the protons in the whole region and the adoption of low efficiency for snr acceleration in the high density regions. the latter is related by us to the well - known low cosmic ray gradient in the galaxy.   a corroborating feature is the close correlation of inferred cosmic ray intensity with the smoothed intensity of 5 ghz radio radiation.   we attribute this to the presence of the snr in the gcr.   plus.1pt minus.1pt -2.0 cm -1.0 cm 1.0 cm    a.d.erlykin @xmath2, a.w.wolfendale @xmath3    \(1 ) p. n. lebedev physical institute, moscow, russia + ( 2 ) department of physics, university of durham, durham, uk
in the models of brane construction, the isometry of a compactified space might be broken by branes. in four - dimensional effective lagrangian,   the breaking of the isometry is seen as the spontaneous breaking of the corresponding effective symmetry.   then it seems natural to expect that there are various kinds of defects that will be implemented by the spontaneous symmetry breaking.   these defects are parametrized by the brane positions. in this paper   we consider two kinds of such `` brane defects '', which are formed by the local fluctuations of the locations of branes along their transversal directions.   the fluctuation of a brane position might leads to winding ( or wraping ) around a non - contractible circle of the compactified space.   these `` primary '' brane defects are already discussed by several authors.   on the other hand, if there are multiple branes in the compactified space and their configuration in a compactified space is determined by the potential that depends only on their relative positions, one might find incidental symmetry in the effective potential, which is spontaneously broken by branes.   we examined the latter `` incidental '' symmetry breakings and stable defect configurations.   we paid special attention to the difference between `` primary '' brane defects.   sit - hep / tm-17    1.5 truecm   .75 truecm    * tomohiro matsuda *   .4 truecm    _ laboratory of physics, saitama institute of technology, _   _ fusaiji, okabe - machi, saitama 369 - 0293, japan _    \1.   truecm addtoresetequationsection 1  . truecm
jewel is a fully dynamical event generator for jet evolution in a dense qcd medium, which has been validated for multiple jet and jet - like observables.   jet constituents ( partons ) undergo collisions with thermal partons from the medium, leading to both elastic and radiative energy loss.   the recoiling medium scattering centers carry away energy and momentum from the jet.   keeping track of these recoils is essential for the description of intra - jet observables. since the thermal component of the recoils is part of the soft background activity, comparison with data on jet observables requires the implementation of a background subtraction procedure.   we will show two independent procedures through which background subtraction can be performed and discuss the impact of the medium recoil on jet shape observables and jet - background correlations. keeping track of the medium recoil significantly improves the jewel description of jet shape measurements.   heavy ion monte carlo generators, background subtraction, jet structure, jet mass
we present the analysis of 1,207 rr lyrae found in photometry taken by the catalina survey s mount lemmon telescope. by combining accurate distances for these stars with measurements for @xmath014,000 type - ab rr lyrae from the catalina schmidt telescope,   we reveal an extended association that reaches galactocentric distances beyond 100 kpc and overlaps the sagittarius streams system.   this result confirms earlier evidence for the existence of an outer halo tidal stream resulting from a disrupted stellar system. by comparing the rr lyrae source density with that expected based on halo models,   we find the detection has @xmath1 significance.   we investigate the distances, radial velocities, metallicities, and period - amplitude distribution of the rr lyrae.   we find that both radial velocities and distances are inconsistent with current models of the sagittarius stream.   we also find tentative evidence for a division in source metallicities for the most distant sources.   following prior analyses, we compare the locations and distances of the rr lyrae with photometrically selected candidate horizontal branch stars and find supporting evidence that this structure spans at least @xmath2 of the sky.   we investigate the prospects of an association between the stream and unusual globular cluster ngc  2419.
we study conditions under which carbon clusters of different sizes form and stabilize.   we describe an approach to equilibrium by simulating tenuous carbon gas dynamics to long times.   first, we use reactive molecular dynamics simulations to describe the nucleation of long chains, large clusters, and complex cage structures in carbon and hydrogen rich interstellar gas phases.   we study how temperature, particle density, presence of hydrogen, and carbon inflow affect the nucleation of molecular moieties with different characteristics, in accordance with astrophysical conditions.   we extend the simulations to densities which are orders of magnitude lower than current laboratory densities, to temperatures relevant to circumstellar environments of planetary nebulae, and to longtime ( microsecond ) formation timescales.   we correlate cluster size distributions from dynamical simulations with thermodynamic equilibrium intuitions, where at low temperatures and gas densities, entropy plays a significant role.
nanodiamond exhibits unpaired electrons in magnetization, epr, nmr and auger relaxation. wave functions and eigenenergies of a bound electron in a nanodiamond crystal have been calculated.   it has been proved by using quantum mechanical analysis that unpaired electrons are self - condition of a nanodiamond as a limited crystal according to tamm theory of surface states.   the surface electron floating over a nanodiamond gives paramagnetic response and stabilizes the nanoparticle at small range of size.   possibly the spin of the floating electron can be used for floating point calculation in future quantum computers on the base of nanodiamond qubits.   
in proto - neutron stars with strong magnetic fields, the cross section for @xmath0 ( @xmath1 ) absorption on neutrons ( protons ) depends on the local magnetic field strength due to the quantization of energy levels for the @xmath2 ( @xmath3 ) produced in the final state.   if the neutron star possesses an asymmetric magnetic field topology in the sense that the magnitude of magnetic field in the north pole is different from that in the south pole, then asymmetric neutrino emission may be generated.   we calculate the absorption cross sections of @xmath4 and @xmath5 in strong magnetic fields as a function of the neutrino energy. these cross sections exhibit oscillatory behaviors which occur because new landau levels for the @xmath2 ( @xmath3 ) become accessible as the neutrino energy increases. by evaluating the appropriately averaged neutrino opacities,   we demonstrate that the change in the local neutrino flux due to the modified opacities is rather small. to generate appreciable kick velocity ( @xmath6  km  s@xmath7 ) to the newly - formed neutron star  , the difference in the field strengths at the two opposite poles of the star must be at least @xmath8  g. we also consider the magnetic field effect on the spectral neutrino energy fluxes.   the oscillatory features in the absorption opacities give rise to modulations in the emergent spectra of @xmath0 and @xmath1.
we investigate the problem of fine tuning of the potential in the  warped flux compactification scenario for brane - antibrane inflation in type iib string theory.   we argue for the importance of an additional parameter @xmath0 ( approximated as zero by ), namely the position of the antibrane, relative to the equilibrium position of the brane in the absence of the antibrane.   we show that for a range of values of a particular combination of the khler modulus, warp factor, and @xmath0, the inflaton potential can be sufficiently flat.   we point out a novel mechanism for dynamically achieving flatness within this part of parameter space : the presence of multiple mobile branes can lead to a potential which initially has a metastable local minimum, but gradually becomes flat as some of the branes tunnel out.   eventually the local minimum disappears and the remaining branes slowly roll together, with assisted inflation further enhancing the effective flatness of the potential. with the addition of khler and superpotential corrections, this mechanism can completely remove the fine tuning problem of brane inflation, within large regions of parameter space. the model can be falsified if future cosmic microwave background observations confirm the hint of a large running spectral index.
the effective potential @xmath0 of a classical ion in a weakly correlated quantum plasma in thermodynamic equilibrium at finite temperature is well described by the rpa screened coulomb potential.   additionally, collision effects can be included via a relaxation time ansatz ( mermin dielectric function ).   these potentials are used to study the quality of various statically screened potentials that were recently proposed by shukla and eliasson ( se ) [ phys.   rev.   lett. * 108 *, 165007 ( 2012 ) ], akbari  moghanjoughi ( am ) [ phys.   plasmas * 22 *, 022103 ( 2015 ) ] and stanton and murillo ( sm ) [ phys. rev.   e * 91 *, 033104 ( 2015 ) ] starting from quantum hydrodynamic theory ( qhd ).   our analysis reveals that the se potential is qualitatively different from the full potential, whereas the sm potential ( at any temperature ) and the am potential ( at zero temperature ) are significantly more accurate. this confirms the correctness of the recently derived [ michta _ et al.   _, contrib. plasma phys. *   55 *, ( 2015 ) ] pre - factor @xmath1 in front of the bohm term of qhd for fermions.
the cross - correlation matrix between equities comprises multiple interactions between traders with varying strategies and time horizons. in this paper, we use the maximum overlap discrete wavelet transform ( modwt ) to calculate correlation matrices over different time scales and then explore the _ eigenvalue spectrum _ over sliding time windows.   the dynamics of the eigenvalue spectrum at different times and scales provides insight into the interactions between the numerous constituents involved.   eigenvalue dynamics are examined for both medium and high - frequency equity returns, with the associated correlation structure shown to be dependent on both time and scale.   additionally, the _ epps _   effect is established using this multivariate method and analysed at longer scales than previously studied.   a partition of the eigenvalue time - series demonstrates, at very short scales, the emergence of negative returns when the largest eigenvalue is greatest.   finally, a portfolio optimisation shows the importance of time - scale information in the context of risk management.   biblabel#1
this paper considers the minimax regret 1-median problem in dynamic path networks. in our model, we are given a dynamic path network consisting of an undirected path with positive edge lengths, uniform positive edge capacity, and nonnegative vertex supplies. here  , each vertex supply is unknown but only an interval of supply is known. a particular assignment of supply to each vertex   is called a _   scenario_. given a scenario @xmath0 and a sink location @xmath1 in a dynamic path network, let us consider the evacuation time to @xmath1 of a unit supply given on a vertex by @xmath0.   the cost of @xmath1 under @xmath0 is defined as the sum of evacuation times to @xmath1 for all supplies given by @xmath0, and the _ median _ under @xmath0 is defined as a sink location which minimizes this cost.   the regret for @xmath1 under @xmath0 is defined as the cost of @xmath1 under @xmath0 minus the cost of the median under @xmath0.   then, the problem is to find a sink location such that the maximum regret for all possible scenarios is minimized.   we propose an @xmath2 time algorithm for the minimax regret 1-median problem in dynamic path networks with uniform capacity, where @xmath3 is the number of vertices in the network.   regret, sink location, dynamic flow, evacuation planning
we show theoretically that thermomechanical effects in dye - doped nematic liquid crystals when illuminated by laser beams, can become important and lead to molecular reorientation at intensities substantially lower than that needed for optical fredericksz transition.   we propose a 1d model that assumes homogenous intensity distribution in the plane of the layer and is capable to describe such a thermally induced threshold lowering.   we consider a particular geometry, with a linearly polarized light incident perpendicularly on a layer of homeotropically aligned dye - doped nematics.
we consider here the massive thirring model regularized with the @xmath0 spin chain.   we numerically calculate the mass ratios of particles which lie in the discrete part of the spectrum and obtain results in accordance with the dhn formula and in disagreement with recent calculations in the literature based on the numerical bethe ansatz and infinite momentum frame methods.   we also analyze the short distance behavior of these states and evaluate the conformal dimensions.   this paper, taken together with the previous one for the sine - gordon model, confirms the duality relation between two models formulated by klassen and melzer [ int  . j. mod.   phys. a * 8 *, 4131 ( 1993 ) ].   # 1@xmath1#1
we study the random link traveling salesman problem, where lengths @xmath0 between city @xmath1 and city @xmath2 are taken to be independent, identically distributed random variables.   we discuss a theoretical approach, the cavity method, that has been proposed for finding the optimum tour length over this random ensemble, given the assumption of replica symmetry. using finite size scaling and a renormalized model, we test the cavity predictions against the results of simulations, and find excellent agreement over a range of distributions.   we thus provide numerical evidence that the replica symmetric solution to this problem is the correct one.   finally, we note a surprising result concerning the distribution of @xmath3th - nearest neighbor links in optimal tours, and invite a theoretical understanding of this phenomenon.   key words : disordered systems, combinatorial optimization, replica symmetry    submitted to _   journal of statistical physics _  , february 1998    final version november 1998
during the last 30 years, and more specifically during the last 10 years, many experiments have been carried out worldwide using different techniques to study the shell evolution of nuclei far from stability.   what seemed not conceivable some decades ago became rather common : all known magic numbers that are present in the valley of stability disappear far from stability and are replaced by new ones at the drip line. by gathering selected experimental results,   beautifully consistent pictures emerge, that very likely take root in the properties of the nuclear forces.the present manuscript describes some of these discoveries and proposes an intuitive understanding of these shell evolutions derived from observations.   extrapolations to yet unstudied regions, as where the explosive r - process nucleosynthesis occurs, are proposed. some remaining challenges and puzzling questions   are also addressed.   @xmath0 : the present manuscript is a summary of a plenary talk given at the 25@xmath1 international nuclear physics conference ( inpc ), firenze, italy, 2 - 7 june 2013. some new remarkable experimental results released since then have been implemented here.
redshift surveys are a powerful tool of modern cosmology.   we discuss two aspects of their power to map the distribution of mass and light in the universe : ( 1 ) measuring the mass distribution extending into the infall regions of rich clusters and ( 2 ) applying deep redshift surveys to the selection of clusters of galaxies and to the identification of very large structures ( great walls ).   we preview the hectomap project, a redshift survey with median redshift @xmath0 covering 50 square degrees to r= 21.   we emphasize the importance and power of spectroscopy for exploring and understanding the nature and evolution of structure in the universe.
we find some new exact cosmological solutions for the covariant scalar - tensor - vector gravity theory, the so - called modified gravity ( mog ).   the exact solution of the vacuum field equations has been derived.   also, for non vacuum cases we have found some exact solutions with the aid of the noether symmetry approach.   more specifically, the symmetry vector and also the noether conserved quantity associated to the point - like lagrangian of the theory have been found.   also we find the exact form of the generic vector field potential of this theory by considering the behavior of the relevant point - like lagrangian under the infinitesimal generator of the noether symmetry.   finally, we discuss the cosmological implications of the solutions.
stick - slip, manifest as intermittent tangential motion between two solids, is a well - known friction instability that occurs in a number of natural and engineering systems. in the context of adhesive polymer interfaces,   this phenomenon has often been solely associated with schallamach waves, which are termed slow waves due to their low propagation speeds.   we study the dynamics of a model polymer interface using coupled force measurements and high speed _ in situ _ imaging, to explore the occurrence of stick - slip linked to other slow wave phenomena.   two new waves  slip pulse and separation pulse  both distinct from schallamach waves, are described.   the slip pulse is a sharp stress front that propagates in the same direction as the schallamach wave, while the separation pulse involves local interface detachment and travels in the opposite direction.   transitions between these stick - slip modes are easily effected by changing the sliding velocity or normal load.   the properties of these three waves, and their relation to stick - slip is elucidated.   we also demonstrate the important role of adhesion in effecting wave propagation.   stick - slip, slow frictional waves, tribology, adhesion, polymers, wear
i describe a new algorithm for solving nonlinear wave equations. in this approach  , evolution takes place on characteristic hypersurfaces.   the algorithm is directly applicable to electromagnetic, yang - mills and gravitational fields and other systems described by second differential order hyperbolic equations.   the basic ideas should also be applicable to hydrodynamics.   it is an especially accurate and efficient way for simulating waves in regions where the characteristics are well behaved.   a prime application of the algorithm is to cauchy - characteristic matching, in which this new approach is matched to a standard cauchy evolution to obtain a global solution. in a model problem of a nonlinear wave  , this proves to be more accurate and efficient than any other present method of assigning cauchy outer boundary conditions.   the approach was developed to compute the gravitational wave signal produced by collisions of two black holes.   an application to colliding black holes is presented.
we present a direct numerical and analytical study of driven supersonic mhd turbulence that is believed to govern the dynamics of star - forming molecular clouds.   we describe statistical properties of the turbulence by measuring the velocity difference structure functions up to the fifth order.   in particular, the velocity power spectrum in the inertial range is found to be close to  @xmath0, and the velocity difference scales as  @xmath1.   the results agree well with the kolmogorov   burgers analytical model suggested for supersonic turbulence in  .   we then generalize the model to more realistic, fractal structure of molecular clouds, and show that depending on the fractal dimension of a given molecular cloud, the theoretical value for the velocity spectrum spans the interval  @xmath2 $ ], while the corresponding window for the velocity difference scaling exponent is  @xmath3 $ ].
we consider quantum plasmas of electrons and motionless ions. we describe separate evolution of spin - up and spin - down electrons.   we present corresponding set of quantum hydrodynamic equations.   we assume that plasmas are placed in an uniform external magnetic field.   we account different occupation of spin - up and spin - down quantum states in equilibrium degenerate plasmas.   this effect is included via equations of state for pressure of each species of electrons.   we study oblique propagation of longitudinal waves.   we show that instead of two well - known waves ( the langmuir wave and the trivelpiece  gould wave ), plasmas reveal four wave solutions.   new solutions exist due to both the separate consideration of spin - up and spin - down electrons _ and _ different occupation of spin - up and spin - down quantum states in equilibrium state of degenerate plasmas.
the imaging atmospheric cherenkov array h.e.s.s.   recently discovered an extended source in the 0.4@xmath010  tev energy range,.   we obtained a 5  ks observation with the acis - i array on the  x - ray observatory that does not reveal an obvious compact or diffuse x - ray counterpart.   archival  images are also blank in this region.   although there are several radio pulsars within the field of, none is detected in x - rays to a flux limit of @xmath1 ergs  @xmath2 s@xmath3, and none is a likely counterpart on energetic grounds. over the entire @xmath4 acis - i field,   we place an upper limit of @xmath5 ergs @xmath2 s@xmath3 on the excess diffuse flux in the @xmath6  kev band.   one hard point - source with flux @xmath7 ergs  @xmath2 s@xmath3 lies within @xmath8 of the centroid of the tev emission.   these exploratory observations suggest that deeper pointings with  and  are needed before we can learn more about the nature of.   its similarity to the unidentified source  indicates the probable existence of a new class of high - energy source in the galactic plane that originates from young, massive stars or their supernova remnants.
the cuore ( _ cryogenic underground observatory for rare events _ ) experiment projects to construct and operate an array of 1000 cryogenic thermal detectors of teo@xmath0, of a mass of 760 g each, to investigate rare events physics, in particular, double beta decay and non baryonic particle dark matter.   a first step towards cuore is cuoricino, an array of 62 of bolometers, currently being installed in the gran sasso laboratory. in this paper   we report the physics potential of both stages of the experiment regarding neutrinoless double beta decay of @xmath1te, wimp searches and solar axions.   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,  ,    ( the cuore collaboration )    pacs : 23.40.-s ; 95.35.+d ; 14.80.mz _ key words _ : underground detectors ; double beta decay ; dark matter ; wimps ; axions.
gravitational wave detectors will need optimal signal - processing algorithms to extract weak signals from the detector noise.   most algorithms designed to date are based on the unrealistic assumption that the detector noise may be modeled as a stationary gaussian process.   however most experiments exhibit a non - gaussian `` tail '' in the probability distribution.   this `` excess '' of large signals can be a troublesome source of false alarms.   this article derives an optimal ( in the neyman - pearson sense, for weak signals ) signal processing strategy when the detector noise is non - gaussian and exhibits tail terms.   this strategy is robust, meaning that it is close to optimal for gaussian noise but far less sensitive than conventional methods to the excess large events that form the tail of the distribution.   the method is analyzed for two different signal analysis problems : ( i ) a known waveform ( e.g., a binary inspiral chirp ) and ( ii ) a stochastic background, which requires a multi - detector signal processing algorithm.   the methods should be easy to implement : they amount to truncation or clipping of sample values which lie in the outlier part of the probability distribution.
the serendipitous extragalactic x - ray source identification ( sexsi ) program is designed to expand significantly the sample of identified extragalactic hard x - ray sources at intermediate fluxes, @xmath0.   sexsi, which includes sources derived from more than 2 deg@xmath1 of _ chandra _ images, provides the largest hard x - ray - selected sample yet studied, offering an essential complement to the _ chandra _ deep fields ( total area @xmath2   deg@xmath1 ). in this paper   we describe @xmath3-band optical imaging of the sexsi fields from the palomar, mdm, and keck observatories.   we have identified counterparts, or derived flux limits for nearly 1000 hard x - ray sources. using the optical images, we derive accurate source positions.   we investigate correlations between optical and x - ray flux, and optical flux and x - ray hardness ratio.   we also study the density of optical sources surrounding x - ray counterparts, as well as the properties of optically - faint, hard x - ray sources.
the nuclear interactions of atomic and low energy antiprotons are studied.   measurements of level shifts and widths in the lightest elements are analyzed and compared with new results obtained in heavy nuclei.   simple geometric properties of @xmath0 nucleus interactions are demonstrated. upon this background   one finds some anomalies that indicate strong energy dependence in the subthreshold @xmath0 nucleon interactions.   the use of of @xmath0 in studies of the nuclear surface is briefly discussed.
we present a radio survey of molecules in a sample of galactic center molecular clouds, including m0.25 + 0.01, the clouds near sgr a, and sgr b2.   the molecules detected are primarily nh@xmath0 and hc@xmath1n ; in sgr b2-n we also detect nonmetastable nh@xmath0, vibrationally - excited hc@xmath1n, torsionally - excited ch@xmath1oh, and numerous isotopologues of these species.   36 ghz class i ch@xmath1oh masers are ubiquitous in these fields, and in several cases are associated with new nh@xmath0 ( 3,3 ) maser candidates.   we also find that nh@xmath0 and hc@xmath1n are depleted or absent toward several of the highest dust column density peaks identified in submillimeter observations, which are associated with water masers and are thus likely in the early stages of star formation.   = 0    the central 300 parsecs of the galaxy contain one of the largest reservoirs of molecular gas in the galaxy.   thus far, however, the large - scale distribution and kinematics of this molecular gas have only been probed at arcminute ( @xmath2 2 - 3 pc ) resolutions ( *???   * ; *???   * ( e.g., bally et al.   1987, jones et al. 2013 ) ).   this survey is a first step toward a uniform study of galactic center gas on sub - parsec scales.   ultimately, these survey data will probe the temperature, density, and kinematics of a sample of clouds at 2 - 3@xmath3 ( @xmath20.1 pc ) resolution.
the accurate description of the optical spectra of insulators and semiconductors remains an important challenge for time - dependent density - functional theory ( tddft ).   evidence has been given in the literature that tddft can produce bound as well as continuum excitons for specific systems, but there are still many unresolved basic questions concerning the role of dynamical exchange and correlation ( xc ). in particular, the role of the long spatial range and the frequency dependence of the xc kernel @xmath0 for excitonic binding are still not very well explored  . we present a minimal model for excitons in tddft, consisting of two bands from a one - dimensional kronig - penney model and simple approximate xc kernels, which allows us to address these questions in a transparent manner. depending on the system  , it is found that adiabatic xc kernels can produce a single bound exciton, and sometimes two bound excitons, where the long spatial range of @xmath0 is not a necessary condition.   it is shown how the wannier model, featuring an effective electron - hole interaction, emerges from tddft. the collective, many - body nature of excitons is explicitly demonstrated.
in this paper, we address the problem of secure wireless information and power transfer in a large - scale multiple - input multiple - output ( ls - mimo ) amplify - and - forward ( af ) relaying system.   the advantage of ls - mimo relay is exploited to enhance wireless security, transmission rate and energy efficiency. in particular,   the challenging issues incurred by short interception distance and long transfer distance are well addressed simultaneously. under very practical assumptions,   i.e., no eavesdropper s channel state information ( csi ) and imperfect legitimate channel csi, this paper investigates the impact of imperfect csi, and obtains an explicit expression of the secrecy outage capacity in terms of transmit power and channel condition.   then, we propose an optimal power splitting scheme at the relay to maximize the secrecy outage capacity. finally, our theoretical claims are validated by simulation results.
the dynamic polarizabilities of the @xmath0, @xmath1 and @xmath2 states of ca@xmath3, are calculated using a relativistic structure model.   the wavelengths at which the stark shifts between different pairs of transitions are zero are computed.   experimental determination of the magic wavelengths can be used to estimate the ratio of the @xmath4 and @xmath5 oscillator strengths.   this could prove valuable in developing better atomic structure models and in particular lead to improved values of the polarizabilities needed in the evaluation of the blackbody radiation shift of the ca@xmath3 ion.
we analyze the line radiative transfer in protoplanetary disks using several approximate methods and a well - tested accelerated monte carlo code. a low - mass flaring disk model with uniform as well as stratified molecular abundances   is adopted.   radiative transfer in low and high rotational lines of co, c@xmath0o, hco@xmath1, dco@xmath1, hcn, cs, and h@xmath2co is simulated.   the corresponding excitation temperatures, synthetic spectra, and channel maps are derived and compared to the results of the monte carlo calculations. a simple scheme that describes the conditions of the line excitation for a chosen molecular transition   is elaborated.   we find that the simple lte approach can safely be applied for the low molecular transitions only, while it significantly overestimates the intensities of the upper lines.   in contrast, the full escape probability ( fep ) approximation can safely be used for the upper transitions ( @xmath3 ) but it is not appropriate for the lowest transitions because of the maser effect. in general,   the molecular lines in protoplanetary disks are partly subthermally excited and require more sophisticated approximate line radiative transfer methods.   we analyze a number of approximate methods, namely, lvg, vep ( vertical escape probability ) and vor ( vertical one ray ) and discuss their algorithms in detail. in addition, two modifications to the canonical monte carlo algorithm that allow a significant speed up of the line radiative transfer modeling in rotating configurations by a factor of 1050 are described.
high energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma - ray flux by inverse compton scattering off the interstellar radiation field.   we develop a numerical tool to compute gamma - ray emission from such electrons and positrons produced in the smooth host halo and in substructure halos with masses down to @xmath0.   we show that the angular power spectrum from inverse compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons.   we also find that the total flux and the shape of the angular power spectrum depends sensitively on the spatial distribution of subhalos in the milky way. finally, the contribution from the smooth host halo component to the gamma - ray mean intensity is negligibly small compared to subhalos.   desy 10 - 131
we discuss full - sky convolution of the instrumental beam with the cmb sky signal in cmb single - dish and interferometry experiments, using the method  @xcite that the measured temperature and polarization anisotropies are defined globally on the group manifold of the three - dimensional rotation by means of wigner d - functions.   we re - derive the anisotropy and polarization correlation functions incorporated with asymmetric window functions, which are then explicitly calculated for a single - dish elliptical gaussian beam and an interferometric gaussian beam.
reflection of a microscopic particle from a mesoscopic / macroscopic ` mirror'generates two - body correlated interference from the incident and reflected particle substates and their associated mirror substates.   the microscopic momentum exchanged generates two mirror substates which interfere to produce fringes which do not vanish as the mirror mass increases.   the small displacement between these mirror states can yield negligible environmental decoherence times.   mirror coherence lengths impose constraints on the extent of this interference, which are mitigated using interference of the two - body states associated with the particle reflecting from both of the two surfaces of a slab of matter in a manner analogous to the classical interference of a pulse of light reflecting from a ` thin film '.   this two - body correlated interference is modeled as a particle traversing a finite well with both the particle and well treated quantum mechanically.   such a treatment predicts the expected ` thin - film'interference but only as a special case of a more general result. it is also shown that measurements on only the reflected particle ( yielding a marginal probability density function )   can act as a probe to reveal the quantum state of the macroscopic reflector. for equal masses, coherence of the particle substate   is transferred to the mirror substate, a quantum manifestation of a familiar classical result.
we test methods for the determination of unstable modes in stellar discs : a point collocation scheme in the action sub - space, a scheme based on expansion of the density and potential on the biorthonormal basis, and a finite element method. using models of galaxies with low and high mass concentration to the centre  , the existence of two different kinds of spectra of unstable modes is demonstrated.   characteristic features of methods and obtained spectra are discussed.    despite ignoring any constraint on the continuity or differentiability of the perturbed distribution function ( df )  , the collocation scheme is reliable for obtaining spectra and patterns in both kinds of models.   the method based on the expansion of the perturbed potential and surface density over a biorthogonal basis was not applicable to a model with high mass concentration.   the finite element method successfully used in various fields of science and engineering is currently sensitive to the presence of resonant orbits due to the choice of interpolation functions for the df.   galaxies : formation, galaxies : kinematics and dynamics.
the new result of a photon - photon scattering experiment in the x - ray region is reported.   an x - ray beam collider is used to divide and collide x - ray beams from an x - ray free electron laser, sacla.   the sensitivity of the experiment is enhanced by an upgraded x - ray beam collider and improvement of the sacla beam quality.   the intensity of the colliding photon beams increased significantly, giving an integrated luminosity of @xmath0.   no signal of scattered x rays was observed. the obtained 95% c.l.   limit on the qed cross section is @xmath1 at @xmath2, which is more stringent by around three orders of magnitude than our previous result.
we have carried out a schrodinger functional ( sf ) calculation for the su(3 ) lattice gauge theory with two flavors of wilson fermions in the sextet representation of the gauge group.   we find that the discrete beta function, which governs the change in the running coupling under a discrete change of spatial scale, changes sign when the sf renormalized coupling is in the neighborhood of @xmath0.   the simplest explanation is that the theory has an infrared - attractive fixed point, but more complicated possibilities are allowed by the data.   while we compare rescalings by factors of 2 and @xmath1, we work at a single lattice spacing.
the optical theorem is applied to the process of electron - positron pair creation in the superposition of a nuclear coulomb and a strong laser field.   we derive new representations for the total production rate as two - fold integrals, both for circular laser polarization and for the general case of elliptic polarization, which has not been treated before.   our approach allows us to obtain by analytical means the asymptotic behaviour of the pair creation rate for various limits of interest.   in particular, we consider pair production by two - photon absorption and show that, close to the energetic threshold of this process, the rate obeys a power law in the laser frequency with different exponents for linear and circular laser polarization. with the help of the upcoming x - ray laser sources our results   could be tested experimentally.
we have investigated au atomic contacts in h@xmath0 and d@xmath0 environment by conductance measurement and @xmath1 spectroscopy.   a single h@xmath0 or d@xmath0 molecule was found to bridge au electrodes. in the case of the au / h@xmath0/au junction  , symmetric peaks were observed in @xmath1 spectra, while they were not observed for the au / d@xmath0/au junction.   the shape of the peaks in @xmath1 spectra originated from the structural change of the single molecule junction induced by the phonon excitation.   the structural change could occur only for the au / h@xmath0/au junction.   the difference in the two single molecule junctions could be explained by larger zero point energy of au - h@xmath0 vibration mode than that in the au / h@xmath0/au junction.
we report on a nanoscale patterning method on si substrates using self - assembled metal islands and low - energy ion - beam irradiation.   the si nanostructures produced on the si substrate have a one - to - one correspondence with the self - assembled metal ( ag, au, pt ) nanoislands initially grown on the substrate.   the surface morphology and the structure of the irradiated surface were studied by high - resolution transmission electron microscopy ( hrtem ).   tem images of ion - beam irradiated samples show the formation of sawtooth - like structures on si. removing metal islands and   the ion - beam induced amorphous si by etching, we obtain a crystalline nanostructure of si.   the smallest structures emit red light when exposed to a uv light.   the size of the nanostructures on si is governed by the size of the self - assembled metal nanoparticles grown on the substrate for this replica nanopatterning.   the method can easily be extended for tuning the size of the si nanostructures by the proper choice of the metal nanoparticles and the ion energy in ion - irradiation.   it is suggested that off - normal irradiation can also be used for tuning the size of the nanostructures.
time of flight positron emission tomography scanner based on plastic scintillators is being developed at the jagiellonian university by the j - pet collaboration.   the main challenge of the conducted research lies in the elaboration of a method allowing application of plastic scintillators for the detection of low energy gamma quanta. in this paper   we report on tests of a single detection module built out from the bc-420 plastic scintillator strip ( with dimensions of 5  x  19  x  300  mm@xmath0 ) read out at two ends by hamamatsu r5320 photomultipliers.   the measurements were performed using collimated beam of annihilation quanta from the @xmath1ge isotope and applying the serial data analyzer ( lecroy sda6000a ) which enabled sampling of signals with 50 ps intervals.   the time resolution of the prototype module was established to be better than 80  ps ( @xmath2 ) for a single level discrimination.   the spatial resolution of the determination of the hit position along the strip was determined to be about 0.93  cm  ( @xmath2 ) for the annihilation quanta.   the fractional energy resolution for the energy e deposited by the annihilation quanta via the compton scattering amounts to @xmath3 and corresponds to the @xmath4 of 7.5% at the compton edge.    `   scintillator detectors `, ` j - pet `, ` positron emission tomography `
strong cluster eccentricity evolution for @xmath0 has appeared in a variety of observational data sets.   we examine the evolution of eccentricity in simulated galaxy clusters using a variety of simulation methodologies, amplitude normalizations, and background cosmologies.   we do not find find such evolution for @xmath1 in any of our simulation ensembles.   we suggest a systematic error in the form of a redshift - dependent selection effect in cluster catalogs or missing physics in cluster simulations important enough to modify the cluster morphology.
we derive here the mean temperature profile for a sample of hot, medium distant clusters recently observed with xmm - newton, whose profiles are available from the literature, and compare it with the mean temperature profile found from bepposax data.   the xmm - newton and bepposax profiles are in good agreement between 0.05 and 0.25 @xmath0. from 0.25 to about 0.5 @xmath0   both profiles decline, however the bepposax profile does so much more rapidly than the xmm - newton profile.
we report theoretical and experimental studies of ambipolar spin diffusion in a semiconductor. a circularly polarized laser pulse is used to excite spin - polarized carriers in a gaas multiple quantum well sample at 80  k. diffusion of electron and spin densities   is simultaneously measured using a spatially and temporally resolved pump - probe technique.   two regimes of diffusion for spin - polarized electrons are observed.   initially, the rate of spin diffusion is similar to that of density diffusion and is controlled by the ambipolar diffusion coefficient. at later times, the spin diffusion slows down considerably relative to the density diffusion and appears to be controlled by a non - constant ( decreasing ) spin diffusion coefficient.   we suggest that the long - time behavior of the spin density can be understood in terms of an inhomogeneous spin relaxation rate, which grows with decreasing density.   the behavior of the spin relaxation rate is consistent with a model of dyakonov - perel relaxation limited by the coulomb scattering between carriers.
greedy algorithm are in widespread use for sparse recovery because of its efficiency.   but some evident flaws exists in most popular greedy algorithms, such as cosamp, which includes unreasonable demands on prior knowledge of target signal and excessive sensitivity to random noise. a new greedy algorithm called amop   is proposed in this paper to overcome these obstacles.   unlike cosamp, amop can extract necessary information of target signal from sample data adaptively and operate normally with little prior knowledge.   the recovery error of amop is well controlled when random noise is presented and fades away along with increase of snr. moreover, amop has good robustness on detailed setting of target signal and less dependence on structure of measurement matrix.   the validity of amop is verified by theoretical derivation.   extensive simulation experiment is performed to illustrate the advantages of amop over cosamp in many respects.   amop is a good candidate of practical greedy algorithm in various applications of compressed sensing.   compressed sensing, greedy algorithm, sparse recovery, noisy environment.
strongly interacting systems are characterized by heavily dressed entities with internal degrees of freedom, which, on a local level, can be described in terms of coherent quantum states.   we examine the modification of these _ local _ coherent quantum states when such entities condense into a _ macroscopic _ coherent quantum state, such as superfluidity. as an example  , we consider a system of electrons coupled to local lattice deformations.   significant changes in the phonon clouds surrounding the charge carriers occur when the system develops into a spatially phase - locked state.   the question of localized self - trapped charge carriers ( bipolarons ) in the normal state becoming delocalized upon entering the superconducting phase is discussed in terms of squeezing of the local coherent phonon states.   suggestions for experimental verifications of these features associated with the lattice dynamics are made.
in this paper, the electronic band structures and its transport properties in the gapped graphene superlattices, with one - dimensional ( 1d ) periodic potentials of square barriers, are systematically investigated.   it is found that a zero averaged wave - number ( zero-@xmath0 ) gap is formed inside the gapped graphene - based superlattices, and the condition for obtaining such a zero-@xmath0 gap is analytically presented.   the properties of this zero-@xmath0 gap including its transmission, conductance and fano factor are studied in detail.   finally it is revealed that the properties of the electronic transmission, conductance and fano factor near the zero-@xmath0 gap are very insensitive to the structural disorder for the finite graphene - based periodic - barrier systems.
in this paper we present the design, calibration method, and initial results of the dual - beam imaging polarimeter ( dbip ).   this new instrument is designed to measure the optical polarization properties of point sources, in particular main belt asteroids.   this instrument interfaces between the tek @xmath0 camera and the university of hawaii s 88-inch telescope, and is available for facility use. using dbip we are able to measure linear polarization with a 1-sigma poisson signal noise of @xmath1 per measurement and a systematic error of order @xmath2   additionally, we discuss measurements of the polarization of the asteroid 16 psyche which were taken as part of the instrument commissioning.   we confirm psyche s negative polarization of @xmath3 but find no significant modulation of the signal with rotation above the @xmath4 polarization level.
the question of whether the pseudogap in high @xmath0 cuprates is related to superconducting precursor effects or to the existence of extrinsic bosonic massive excitations is investigated on the basis of the boson - fermion model.   the characteristic three peak structure of the electronic spectral function and the temperature dependent fermi vector derived here are signatures for a two component scenario which can be tested by arpes and bis experiments.
using the previously developed model to describe laminar / turbulent states of a viscous fluid flow, which treats the flow as a collection of coherent structures of various size ( chekmarev, chaos, 2013, 013144 ), the statistical temperature of the flow state is determined as a function of the reynolds number.   it is shown that at small reynolds numbers, associated with laminar states, the temperature is positive, while at large reynolds numbers, associated with turbulent states, it is negative. at intermediate reynolds numbers, the temperature changes from positive to negative as the size of the coherent structures increases, similar to what was predicted by onsager for a system of parallel point - vortices in an inviscid fluid.   it is also shown that in the range of intermediate reynolds numbers the temperature exhibits a power - law divergence characteristic of second - order phase transitions.
the spitzer adaptation of the red - sequence cluster survey ( sparcs ) is a @xmath0-passband imaging survey of the 50 deg@xmath1 spitzer swire legacy fields, designed with the primary aim of creating the first large, homogeneously selected sample of massive clusters at @xmath2.   sparcs uses an infrared adaptation of the two - filter cluster red - sequence technique. in this paper   we report keck / lris spectroscopic confirmation of two new exceptionally rich galaxy clusters, sparcs j161315 + 564930  at @xmath3, with 14 high - confidence members and a rest - frame velocity dispersion of @xmath4 km s@xmath5, and sparcs j161641 + 554513  at @xmath6, with seven high - confidence members ( including one agn ) and a rest - frame velocity dispersion of @xmath7 km  s@xmath5.   we also report confirmation of a third new system, sparcs j161037 + 552417  at @xmath8, with seven high - confidence members and a rest - frame velocity dispersion of @xmath9 km s@xmath5.   these three new spectroscopically confirmed clusters further demonstrate the efficiency and effectiveness of two - filter imaging for detecting _ bona fide _   galaxy clusters at high redshift.   we conclude by demonstrating that prospects are good for the current generation of surveys aiming to estimate cluster redshifts and masses at @xmath10 _ directly _ from optical - infrared imaging.
the interior of cells is crowded thus making it important to assess the effects of macromolecules on the folding of proteins. using the self - organized polymer ( sop ) model,   which is a coarse - grained representation of polypeptide chains, we probe the mechanical stability of ubiquitin ( ub ) monomers and trimers ( ( ub)@xmath0 ) in the presence of monodisperse spherical crowding agents. crowding increases the volume fraction ( @xmath1)-dependent average force ( @xmath2 ), relative to the value at @xmath3, needed to unfold ub and the polyprotein. for a given @xmath1, the values of @xmath2 increase as the diameter ( @xmath4 ) of the crowding particles decreases.   the average unfolding force @xmath2 depends on the ratio @xmath5, where @xmath6 with @xmath7 being the radius of gyration of ub ( or ( ub)@xmath0 ) in the unfolded state.   examination of the unfolding pathways shows that, relative to @xmath3, crowding promotes reassociation of ruptured secondary structural elements.   both the nature of the unfolding pathways and @xmath2 for ( ub)@xmath0 are altered in the presence of crowding particles with the effect being most dramatic for the subunit that unfolds last.   we predict, based on sop simulations and theoretical arguments, that @xmath8, where @xmath9 is the flory exponent that describes the unfolded ( random coil ) state of the protein.   @xmath10biophysics program, institute for physical science and technology + @xmath11department of chemistry and biochemistry + @xmath12university of maryland, college park, md 20742 + keywords : depletion effect, entropic stabilization, crowders, afm
we have determined the total numbers and specific frequencies of blue, metal - poor globular clusters ( gcs ) in eight spiral and early - type galaxies.   these data, along with five measurements from the literature, show a trend of increasing blue gc specific frequency with increasing mass of the host galaxy.   the increase is not accounted for in a simple galaxy formation model in which ellipticals and their gc systems are formed by the merger of typical spiral galaxies.   the data appear broadly consistent with hierarchical formation scenarios in which metal - poor gcs are formed over a finite period in the early universe during the initial stages of galaxy assembly. in this picture, the observed trend is related to biasing, in the sense that the more massive galaxies of today began assembling earlier and therefore formed relatively more gcs during this early epoch of metal - poor gc formation.   we discuss how comparisons of the observed specific frequency of metal - poor gcs with model calculations can constrain the formation redshift of these objects.
the recently discovered multiband superconductors have created a new class of novel superconductors. in these materials   multiple superconducting gaps arise due to the formation of cooper pairs on different sheets of the fermi surfaces.   an important feature of these superconductors is the interband couplings, which not only change the individual gap properties, but also create new collective modes.   here we investigate the effect of the interband couplings in the ginzburg - landau theory.   we produce a general @xmath0 expansion ( @xmath1 ) and show that this expansion has unexpected behaviour for @xmath2.   this point emphasises the weaker validity of the gl theory for lower temperatures and gives credence to the existence of hidden criticality near the critical temperature of the uncoupled subdominant band.
the time evolution of a wavepacket in strained graphene is studied within the tight - binding model and continuum model.   the effect of an external magnetic field, as well as a strain - induced pseudo - magnetic field, on the wave packet trajectories and zitterbewegung are analyzed.   combining the effects of strain with those of an external magnetic field produces an effective magnetic field which is large in one of the dirac cones, but can be practically zero in the other.   we construct an efficient valley filter, where for a propagating incoming wave packet consisting of momenta around the @xmath0 and @xmath1 dirac points, the outgoing wave packet exhibits momenta in only one of these dirac points, while the components of the packet that belong to the other dirac point are reflected due to the lorentz force.   we also found that the zitterbewegung is permanent in time in the presence of either external or strain - induced magnetic fields, but when both the external and strain - induced magnetic fields are present, the zitterbewegung is transient in one of the dirac cones, whereas in the other cone the wave packet exhibits permanent spatial oscillations.
we construct families of pairs of heegaard splittings that must be stabilized several times to become equivalent.   the first such pair differs only by their orientation.   these are genus @xmath0 splittings of a closed 3-manifold that must be stabilized at least @xmath1 times to become equivalent.   the second is a pair of genus @xmath0 splittings of a manifold with toroidal boundary that must be stabilized at least @xmath2 times to become equivalent.   the last example is a pair of genus @xmath0 splittings of a closed 3-manifold that must be stabilized at least @xmath3 times to become equivalent, regardless of their orientations.   all of these examples are splittings of manifolds that are obtained from simpler manifolds by gluing along incompressible surfaces via  sufficiently complicated " maps.
the pole structure of the @xmath0 is examined by fitting the couplings of an underlying hamiltonian effective field theory to cross sections of @xmath1 scattering in the infinite - volume limit.   finite - volume spectra are then obtained from the theory, and compared to lattice qcd results for the mass of the @xmath0.   momentum - dependent, non - separable potentials from well - known weinberg - tomozawa terms are used.   in addition, we examine the effect on the behaviour of the spectra from the inclusion of a bare triquark - like isospin - zero basis state.   it is found that the cross sections are consistent with the experimental data with two complex poles for the @xmath0, regardless of whether a bare baryon basis state is introduced or not.   however, it is apparent that the bare baryon is important for describing the results of lattice qcd at high pion masses.
we perform an ab - initio calculation for the binding energy of @xmath0 using the cd - bonn 2000 nn potential renormalized with the lee - suzuki method.   the many - body approach to the problem is the hybrid multideterminant method.   the results indicate a binding energy of about @xmath1, within a few hundreds kev uncertainty. the center of mass diagnostics are also discussed.    *   pacs numbers * : 21.60.de, @xmath2 21.10.dr, @xmath2 27.20.+n
we obtained high resolution, high s / n spectroscopy for the very metal - poor star hd  122563 with the subaru telescope high dispersion spectrograph.   previous studies have shown that this object has excesses of light neutron - capture elements, while its abundances of heavy ones are very low. in our spectrum covering 3070  4780    of this object,   19 neutron - capture elements have been detected, including seven for the first time in this star ( nb, mo, ru, pd, ag, pr, and sm ).   upper limits are given for five other elements including th.   the abundance pattern shows a gradually decreasing trend, as a function of atomic number, from sr to yb, which is quite different from those in stars with excesses of r - process elements.   this abundance pattern of neutron - capture elements provides new strong constraints on the models of nucleosynthesis responsible for the very metal - poor stars with excesses of light neutron - capture elements but without enhancement of heavy ones.
we investigate the combined influence of a magnetic field and a harmonic interparticle interaction on the thermodynamic properties of a finite number of spin polarized fermions in a confiment potential.   this study is an extension using our path integral approach of symmetrized density matrices for identical particles.   the thermodynamical properties are calculated for a three dimensional model of @xmath0 harmonically interacting spin polarized fermions in a parabolic potential well in the presence of a magnetic field.   the free energy and the internal energy are obtained for a limited number of particles.   deviations from the thermodynamical limit become negligible for about 100 or more particles, but even for a smaller number of fermions present in the well, scaling relations similar to those of the continuum approximation to the density of states are already satisfied.   acknowledgement algorithm axiom claim conclusion condition conjecture corollary criterion definition example exercise lemma notation problem proposition remark solution summary
we report very intense and variable h@xmath0 emission ( pseudo - equivalent widths of @xmath1180, 410 ) of sori55, a probable free - floating, m9-type substellar member of the young @xmath2orionis open star cluster.   after comparison with state - of - the - art evolutionary models, we infer that sori55 is near or below the cluster deuterium - burning mass borderline, which separates brown dwarfs and planetary - mass objects.   we find its mass to be 0.0080.015@xmath3 for ages between 1myr and 8myr, with @xmath10.012@xmath3 the most likely value at the cluster age of 3myr.   the largest h@xmath0 intensity reached the saturation level of log@xmath4/@xmath5=3.   we discuss several possible scenarios for such a strong emission.   we also show that @xmath2orionis m and l dwarfs have in general more h@xmath0 emission than their older field spectral counterparts.   this could be due to a decline in the strength of the magnetic field with age in brown dwarfs and isolated planetary - mass objects, or to a likely mass accretion from disks in the very young @xmath2orionis substellar members.
a key feature of non - equilibrium thermodynamics is the markovian, deterministic relaxation of coarse observables such as, for example, the temperature difference between two macroscopic objects which evolves independently of almost all details of the initial state.   we demonstrate that the unitary dynamics for moderately sized spin-1/2 systems may yield the same type of relaxation dynamics for a given magnetization difference.   this observation might contribute to the understanding of the emergence of thermodynamics within closed quantum systems.
quantum coherence is the yield of the superposition principle.   recently, it has been theorized as a quantum resource, and is the premise of quantum correlations in multipartite systems. however, coherence is degraded by environmental interactions.   it is therefore natural to study the coherence content and its distribution in a multipartite quantum system. in this work,   we show analytically as well as numerically the reciprocity between coherence and mixedness of a quantum state.   it appears that this trade - off is a general feature rather being exotic.   we also study the distribution of coherence in multipartite systems and prove several interesting results.   numerical investigation unravels the fact that the percent of quantum states satisfying the additivity relation of coherence increases with increasing number of parties, the rank of quantum state and raising the power of coherence measure under investigation.   we also study distribution of coherence in x states.   we further show that for dicke states, while the normalized measures of coherence violate the additivity relation, the unnormalized ones do satisfy the same.
the energy method can be used to identify well - posed initial boundary value problems for quasi - linear, symmetric hyperbolic partial differential equations with maximally dissipative boundary conditions.   a similar analysis of the discrete system can be used to construct stable finite difference equations for these problems at the linear level. in this paper   we apply these techniques to some test problems commonly used in numerical relativity and observe that while we obtain convergent schemes, fast growing modes, or `` artificial instabilities, '' contaminate the solution.   we find that these growing modes can partially arise from the lack of a leibnitz rule for discrete derivatives and discuss ways to limit this spurious growth.
we report multi - wavelength observations of the unidentified _ fermi _  object 2fglj1653.6-0159. with the help of high - resolution x - ray observation  , we have identified an x - ray and optical counterpart of 2fglj1653.6-0159.   the source exhibits a periodic modulation of 75 min in optical and possibly also in x - ray.   we suggest that 2fglj1653.6-0159  is a compact binary system with an orbital period of 75 min. combining the gamma - ray and x - ray properties,   2fglj1653.6-0159  is potentially a black widow / redback type gamma - ray millisecond pulsar ( msp ).   the optical and x - ray lightcurve profiles show that the companion is mildly heated by the high - energy emission and the x - rays are from intrabinary shock.   although no radio pulsation has been detected yet, we estimated that the spin period of the msp is @xmath0 ms based on a theoretical model. if pulsation can be confirmed in the future, 2fglj1653.6-0159  will become the first ultracompact rotation - powered msp.
we explore the nature of the small - scale solar dynamo by tracking magnetic features.   we investigate two previously - explored categories of the small - scale solar dynamo : shallow and deep.   recent modeling work on the shallow dynamo has produced a number of scenarios for how a strong network concentration can influence the formation and polarity of nearby small - scale magnetic features.   these scenarios have measurable signatures, which we test for here using magnetograms from the narrowband filter imager ( nfi ) on _ hinode_. we find no statistical tendency for newly - formed magnetic features to cluster around or away from network concentrations, nor do we find any statistical relationship between their polarities. we conclude that there is no shallow or `` surface '' dynamo on the spatial scales observable by _ hinode_/nfi. in light of these results,   we offer a scenario in which the sub - surface field in a deep solar dynamo is stretched and distorted via turbulence, allowing the field to emerge at random locations on the photosphere.
_ galex _ near ultraviolet ( nuv ) and far - ultraviolet ( fuv ) light curves of three extremely low accretion rate polars show distinct modulations in their uv light curves.   while these three systems have a range of magnetic fields from 13 to 70 mg, and of late type secondaries ( including a likely brown dwarf in sdssj121209.31 + 013627.7 ), the accretion rates are similar, and the uv observations imply some mechanism is operating to create enhanced emission zones on the white dwarf.   the uv variations match in phase to the two magnetic poles viewed in the optical in wx lmi and to the single poles evident in the optical in sdssj1212109.31 + 013627.7 and sdssj103100.55 + 202832.2.   simple spot models of the uv light curves show that if hot spots are responsible for the uv variations, the temperatures are on the order of 10,000 - 14,000k.   for the single pole systems, the size of the fuv spot must be smaller than the nuv and in all cases, the geometry is likely more complicated than a simple circular spot.
we revisit an integrable lattice model of polymer collapse using numerical simulations.   this model was first studied by blte and nienhuis in j. phys.   a. * 22 *, 1415 ( 1989 ) and it describes polymers with some attraction, providing thus a model for the polymer collapse transition. at a particular set of boltzmann weights   the model is integrable and the exponents @xmath0 and @xmath1 have been computed via identification of the scaling dimensions @xmath2 and @xmath3.   we directly investigate the polymer scaling exponents via monte carlo simulations using the perm algorithm. by simulating this polymer model for   walks up to length @xmath4 we find @xmath5 and @xmath6, which are clearly different from the predicted values. our estimate for the exponent @xmath7 is compatible with the known @xmath8-point value of @xmath9 and in agreement with very recent numerical evaluation by foster and pinettes @xcite.
the motion of classical spinning test particles in the equatorial plane of a kerr black hole is considered for the case where the particle spin is perpendicular to the equatorial plane.   we review some results of our recent research of the innermost stable circular orbits ( isco ) @xcite and present some new calculations.   the isco radius, total angular momentum, energy, and orbital angular frequency are considered.   we calculate the isco parameters numerically for different values of the kerr parameter @xmath0 and investigate their dependence on both black hole and test particle spins.   then we describe in details how to calculate analytically small - spin corrections to the isco parameters for an arbitrary values of @xmath0.   the cases of schwarzschild, slowly rotating kerr and extreme kerr black hole are considered.   the use of the orbital angular momentum is discussed.   we also consider the isco binding energy.   it is shown that the efficiency of accretion onto an extreme kerr black hole can be larger than the maximum known efficiency ( 42 @xmath1 ) if the test body has a spin.
the compressive yield stress of particle gels shows a highly nonlinear dependence on the packing fraction.   we have studied continuous compression processes, and discussed the packing fraction dependence with the particle scale rearrangements.   the 2d simulation of uniaxial compression was applied to fractal networks, and the required compressive stresses were evaluated for a wide range of packing fractions that approached close packing. the compression acts to reduce the size of the characteristic structural entities ( i.e. the correlation length of the structure ).   we observed three stages of compression : ( i ) elastic - dominant regime ; ( ii ) single - mode plastic regime, where the network strengths are determined by the typical length scale and the rolling mode ; and ( iii ) multi - mode plastic regime, where sliding mode and connection breaks are important.   we also investigated the way of losing the fractal correlation under compression.   it turns out that both fractal dimension @xmath0 and correlation length @xmath1 start to change from the early stage of compression, which is different from the usual assumption in theoretical models.
the kondo effect may be observable in some atom - surface scattering experiments, in particular, those involving alkaline - earth atoms. by combining keldysh techniques with the nca approximation to solve the time - dependent newns - anderson hamiltonian in the @xmath0 limit, shao, nordlander, and langreth found an anomalously strong surface - temperature dependence of the outgoing charge state fractions. here   we employ a dynamical @xmath1 expansion with a finite coulomb interaction @xmath2 to give a more realistic description of the scattering process.   we test the accuracy of the @xmath1 expansion in the @xmath3 case of spinless fermions against the exact independent particle solution.   we then compare results obtained in the @xmath0 limit with the nca approximation at @xmath4 and recover qualitative features already found.   finally, we analyze the realistic situation of ca atoms with @xmath5 ev scattered off cu(001 ) surfaces.   although the presence of the doubly - ionized ca@xmath6 species can change the absolute scattered ca@xmath7 yields, the temperature dependence is qualitatively the same as that found in the @xmath0 limit.   one of the main difficulties that experimentalists face in attempting to detect this effect is that the atomic velocity must be kept small enough to limit kinematic smearing of the fermi surface of the metal.
molecular clouds are expected to emit non - thermal radiation due to cosmic ray interactions in the dense magnetized gas.   such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if energetic particles can leave the accelerator site and diffusively reach the cloud.   we consider here the situation in which a molecular cloud is located in the proximity of a supernova remnant which is efficiently accelerating cosmic rays and gradually releasing them in the interstellar medium.   we calculate the multiwavelength spectrum from radio to gamma rays which is emerging from the cloud as the result of cosmic ray interactions.   the total energy output is dominated by the gamma ray emission, which can exceed the emission in other bands by an order of magnitude or more.   this suggests that some of the unidentified tev sources detected so far, with no obvious or very weak counterparts in other wavelengths, might be in fact associated with clouds illuminated by cosmic rays coming from a nearby source.   moreover, under certain conditions, the gamma ray spectrum exhibit a concave shape, being steep at low energies and hard at high energies.   this fact might have important implications for the studies of the spectral compatibility of gev and tev gamma ray sources.   
in this paper i report the highlights of the talk : `` universal properties in galaxies and cored dm profiles '', given at : colloquium lectures, ecole internationale dastrophysique daniel chalonge.   the 14th paris cosmology colloquium 2010 `` the standard model of the universe : theory and observations ''.
unified x - ray spectral and timing studies of cygnus x-1 in the low / hard and hard intermediate state were conducted in a model - independent manner, using broadband suzaku data acquired on 25 occasions from 2005 to 2009 with a total exposure of @xmath0 ks.   the unabsorbed 0.1500 kev source luminosity changed over 0.82.8% of the eddington limit for 14.8 solar masses.   variations on short ( 12 seconds ) and long ( days to months ) time scales require at least three separate components : a constant component localized below @xmath12  kev, a broad soft one dominating in the 210 kev range, and a hard one mostly seen in 10300 kev range. in view of the truncated disk / hot inner flow picture,   these are respectively interpreted as emission from the truncated cool disk, a soft compton component, and a hard compton component.   long - term spectral evolution can be produced by the constant disk increasing in temperature and luminosity as the truncation radius decreases.   the soft compton component likewise increases, but the hard compton does not, so that the spectrum in the hard intermediate state is dominated by the soft compton component ; on the other hand, the hard compton component dominates the spectrum in the dim low / hard state, probably associated with a variable soft emission providing seed photons for the comptonization.
we investigate the power of weak measurements in the framework of quantum state discrimination.   first, we define and analyze the notion of weak consecutive measurements.   our main result is a convergence theorem whereby we demonstrate when and how a set of consecutive weak measurements converges to a strong measurement.   second, we show that for a small set of consecutive weak measurements, long before their convergence, one can separate close states without causing their collapse.   we thus demonstrate a tradeoff between the success probability and the bias of the original vector towards collapse.   next we use post - selection within the two - state - vector formalism and present the non - linear expansion of the expectation value of the measurement device s pointer to distinguish between two predetermined close vectors.
in the present paper we study generation of the synchrotron emission by means of the feedback of cherenkov drift waves on the particle distribution via the diffusion process.   it is shown that despite the efficient synchrotron losses the excited cherenkov drift instability leads to the quasi - linear diffusion ( qld ), effect of which is balanced by dissipation factors and as a result the pitch angles are prevented from damping, maintaining the corresponding synchrotron emission.   the model is analyzed for a wide range of physical parameters and it is shown that the mechanism of qld guarantees the generation of electromagnetic radiation from soft @xmath0-rays up to soft @xmath1-rays, strongly correlated with cherenkov drift emission ranging from ir up to uv energy domains.
we propose a method to study the nature of exotic hadrons by determining the wave function renormalization constant @xmath0 from lattice simulations.   it is shown that, instead of studying the volume - dependence of the spectrum, one may investigate the dependence of the spectrum on the twisting angle, imposing twisted boundary conditions on the fermion fields on the lattice. in certain cases,   e.g., the case of the @xmath1 bound state which is addressed in detail, it is demonstrated that the partial twisting is equivalent to the full twisting up to exponentially small corrections.
motivated by the recently discovered class of faint ( 10@xmath010@xmath1 ergss@xmath2 ) x - ray transients in the galactic center region, we investigate the 210 kev properties of classical and recurrent novae.   existing data are consistent with the idea that all classical novae are transient x - ray sources with durations of months to years and peak luminosities in the 10@xmath010@xmath1 ergss@xmath2  range.   this makes classical novae a viable candidate class for the faint galactic center transients.   we estimate the rate of classical novae within a 15 arcmin radius region centered on the galactic center ( roughly the field of view of _ xmm - newton _  observations centered on sgr a * ) to be @xmath30.1 per year.   therefore, it is plausible that some of the galactic center transients that have been announced to date are unrecognized classical novae.   the continuing monitoring of the galactic center region carried out by _ chandra _  and _ xmm - newton _  may therefore provide a new method to detect classical novae in this crowded and obscured region, where optical surveys are not, and can never hope to be, effective.   therefore, x - ray monitoring may provide the best means of testing the completeness of the current understanding of the nova populations.
active colloids and externally actuated semi - flexible filaments provide basic building blocks for designing autonomously motile micro - machines. here  , we show that a passive semi - flexible filament can be actuated and transported by attaching an active colloid to its terminus.   we study the dynamics of this assembly when it is free, tethered, or clamped using overdamped equations of motion that explicitly account for active fluid flow and the forces it mediates.   linear states are destabilized by buckling instabilities to produce stable states of non - zero curvature and writhe.   we demarcate boundaries of these states in the two - dimensional parameter space representing dimensionless measures of polar and apolar activity.   our proposed assembly can be used as a novel component in the design of micro - machines at low reynolds number and to study elastic instabilities driven by `` follower '' forces.
this paper considers an amplify - and - forward relay network with fading states.   amplify - and - forward scheme ( along with its variations ) is the core mechanism for enabling cooperative communication in wireless networks, and hence understanding the network stability region under amplify - and - forward scheme is very important.   however, in a relay network employing amplify - and - forward, the interaction between nodes is described in terms of real - valued `` packets '' ( signals ) instead of discrete packets ( bits ).   this restrains the relay nodes from re - encoding the packets at desired rates.   hence, the stability analysis for relay networks employing amplify - and - forward scheme is by no means a straightforward extension of that in packet - based networks. in this paper,   the stability region of a four - node relay network is characterized, and a simple throughput optimal algorithm with joint scheduling and rate allocation is proposed.
in this work, we investigate the statistical computation of the boltzmann entropy of statistical samples. for this purpose,   we use both histogram and kernel function to estimate the probability density function of statistical samples.   we find that, due to coarse - graining, the entropy is a monotonic increasing function of the bin width for histogram or bandwidth for kernel estimation, which seems to be difficult to select an optimal bin width / bandwidth for computing the entropy.   fortunately, we notice that there exists a minimum of the first derivative of entropy for both histogram and kernel estimation, and this minimum point of the first derivative asymptotically points to the optimal bin width or bandwidth.   we have verified these findings by large amounts of numerical experiments.   hence, we suggest that the minimum of the first derivative of entropy be used as a selector for the optimal bin width or bandwidth of density estimation  . moreover, the optimal bandwidth selected by the minimum of the first derivative of entropy is purely data - based, independent of the unknown underlying probability density distribution, which is obviously superior to the existing estimators.   our results are not restricted to one - dimensional, but can also be extended to multivariate cases.   it should be emphasized, however, that we do not provide a robust mathematical proof of these findings, and we leave these issues with those who are interested in them.       methods : data analysis  methods : numerical  methods : statistical  cosmology : theory  large - scale structure of universe.
thermally fluctuating sheets and ribbons provide an intriguing forum in which to investigate strong violations of hooke s law : large distance elastic parameters are in fact not constant, but instead depend on the macroscopic dimensions.   inspired by recent experiments on free - standing graphene cantilevers, we combine the statistical mechanics of thin elastic plates and large - scale numerical simulations to investigate the thermal renormalization of the bending rigidity of graphene ribbons clamped at one end. for ribbons of dimensions @xmath0, @xmath1,   the macroscopic bending rigidity @xmath2 determined from cantilever deformations is independent of the width when @xmath3, where @xmath4 is a thermal length scale, as expected.   when @xmath5, however, this thermally renormalized bending rigidity begins to systematically increase, in agreement with the scaling theory, although our data is not good enough to determine the expected power law dependence on @xmath6.   when the ribbon length @xmath7, where @xmath8 is the @xmath6-dependent thermally renormalized ribbon persistence length, we observe a scaling collapse and the beginnings of large scale random walk behavior.
recent rosat studies of narrow - line seyfert 1 galaxies revealed these objects ( with fwhm @xmath0 ) generally show steeper soft x - ray spectra than broad line seyfert 1 s and that there are no agn with broad lines and steep x - ray spectra. we derive a simple theoretical model which explains this observed correlation between the line width and the spectral index for seyfert 1 galaxies. assuming the line width is due to gravitational velocity dispersion, it is determined by the radius of the broad line region.   sources with steep x - ray spectra ( for a given luminosity ) have a stronger ionizing power than flat - spectrum sources with comparable luminosity, which implies that the blr is formed at relatively larger distances from the central source, and hence has a smaller velocity dispersion and a smaller observed fwhm.   we test the model over a hetrogeneous ( normal and narrow - line ) sample of some 50 agn finding a good agreement with the data.
we address the problem of calculating momentum distributions of particles emerging from the three - body decay of a many - body resonance.   we show that these distributions are determined by the asymptotics of the coordinate - space complex - energy wave - function of the resonance.   we use the hyperspherical adiabatic expansion method where all lengths are proportional to the hyperradius.   the structures of the resonances are related to different decay mechanisms. for direct decay all inter - particle distances increase proportional to the hyperradius at intermediate and large distances.   sequential three - body decay proceeds via spatially confined quasi - stationary two - body configurations.   then two particles remain close while the third moves away. the wave function may contain mixtures which produce coherence effects at small distances, but the energy distributions can still be added incoherently.   two - neutron halos are discussed in details and illustrated by the @xmath0 resonance in @xmath1he.   the dynamic evolution of the decay process is discussed.   21.45.+v, 31.15.ja, 25.70.ef
we numerically show that time delayed coherent feedback controls the statistical output characteristics of driven quantum emitters.   quantum feedback allows to enhance or suppress a wide range of classical and nonclassical features of the emitted quantum light. as exemplary quantum system,   we use a pumped cavity containing two emitters. by applying phase - selective feedback,   we demonstrate that photon antibunching and bunching can be increased in orders of magnitude due to intrinsically and externally controllabe quantum interferences.   our modelling is based on a fully non - markovian quantum simulation of a structured photon continuum.   we show that an approximative method in the schrdinger picture allows a very good estimate for quantum feedback induced features for low pump rates.
we study the correspondence between field theoretic and holographic dark energy density of the universe with the modified chaplygin gas ( mcg ) respectively both in a flat and non - flat frw universe.   we present an equivalent representation of the mcg with a homogeneous minimally coupled scalar field by constructing the corresponding potential.   a new scalar field potential is obtained here which is physically realistic and important for cosmological model building.   in addition we also present holographic dark energy model described by the mcg.   the dynamics of the corresponding holographic dark energy field is determined by reconstructing the potential in a non - flat universe.   the stability of the holographic dark energy in this case in a non - flat universe is also discussed.   = 11    pacs number(s ) : 04.20.jb, 98.80.cq, 98.80.-k
we study a dynamic mechanism to passively suppress the thermal noise of a micromechanical resonator through an intrinsic self - feedback that is genuinely non - markovian.   we use two coupled resonators, one as the target resonator and the other as an ancillary resonator, to illustrate the mechanism and its noise reduction effect.   the intrinsic feedback is realized through the dynamics of coupling between the two resonators : the motions of the target resonator and the ancillary resonator mutually influence each other in a cyclic fashion.   specifically, the states that the target resonator has attained earlier will affect the state it attains later due to the presence of the ancillary resonator.   we show that the feedback mechanism will bring forth the effect of noise suppression in the spectrum of displacement, but not in the spectrum of momentum.
doubts have been expressed on the universality of holographic / string - inspired quantization rules for the horizon areas of stationary black holes, or the products of their radii, already in 4-dimensional general relativity.   realistic black holes are not stationary but time - dependent. we produce three examples of 4d general - relativistic spacetimes containing dynamical black holes for at least part of the time, and   we show that the quantization rules ( even counting virtual horizons ) can not hold, except possibly at isolated instants of time, and do not seem to be universal.
the angstrom project is using a distributed network of two - meter class telescopes to conduct a high cadence pixel - lensing survey of the bulge of the andromeda galaxy ( m31 ). with the expansion of global telescope network  , the detection efficiency of pixel - lensing surveys is rapidly improving. in this paper  , we estimate the detection rate of binary lens events expected from high - cadence pixel - lensing surveys toward m31 such as the angstrom project based on detailed simulation of events and application of realistic observational conditions. under the conservative detection criteria that only high signal - to - noise caustic - crossing events with long enough durations between caustic crossings can be firmly identified as binary lens events  , we estimate that the rate would be @xmath0 per season, where @xmath1 is the fraction of binaries with projected separations of @xmath2 out of all lenses and @xmath3 is the rate of stellar pixel - lensing events.   we find that detected binaries would have mass ratios distributed over a wide range of @xmath4 but with separations populated within a narrow range of @xmath5.   implementation of an alert system and subsequent follow - up observations would be important not only for the increase of the binary lens event rate but also for the characterization of lens matter.
based on micromagnetic theory we have derived analytical expressions for the magnetic small - angle neutron scattering ( sans ) cross section of a two - phase particle - matrix - type ferromagnet. the approach   valid close to magnetic saturation  provides access to several features of the spin structure such as perturbing magnetic anisotropy and magnetostatic fields.   depending on the applied magnetic field and on the magnitude @xmath0 of the magnetic anisotropy field relative to the magnitude @xmath1 of the jump in the longitudinal magnetization at the particle - matrix interface, we observe a variety of angular anisotropies in the magnetic sans cross section.   in particular, the model explains the `` clover - leaf''-shaped angular anisotropy which was previously observed for several nanostructured magnetic materials, and it provides access to the magnetic interaction parameters such as the average exchange - stiffness constant.   it is also shown that the ratio @xmath2 decisively determines the asymptotic power - law exponent and the range of spin - misalignment correlations.
the tiny general relativistic  can be measured by means of a suitable combination of the orbital residuals of the nodes of  and and the  of.   this observable is affected, among other factors, by the earth s solid and ocean tides.   they induce long - period orbital perturbations that, over observational periods of few years, may alias the detection of the  secular trend of interest. in this paper   we calculate explicitly the most relevant tidal perturbations acting upon s and assess their influence on the detection of the .   the present day level of knowledge of the solid and ocean tides allow us to conclude that their influence on it ranges from almost @xmath0 over 4 years to less than @xmath1 over 7 years.   # 1eq.( ) # 1#2eqs.()-( ) # 1eq.( ) # 1#2eqs.()-( ) # 1 # 1#2 # 1#2#3#4 ( ) # 1#2 # 1   u ps.   # 1  # 1 # 1#2#1#2 # 1 # 1#2 # 1#2 # 1 # 1#2_#1^#2 # 1 # 1 # 1_#1 _
a new cataclysmic variable is identified as the optical counterpart of the faint and hard x - ray source rxj0757.0 + 6306 discovered during the rosat all - sky survey.   strong double - peaked emission lines bear evidence of an accretion disc via an s  wave which varies with a period of 81@xmath0  min.   we identify this period as the orbital period of the binary system.   ccd photometry reveals an additional period of 8.52@xmath1 min. which was stable over four nights.   we suggest that  is possibly an intermediate polar, but we can not exclude the possibility that it is a member of the su uma group of dwarf novae.    _ _ _ = = = 1=1=0pt = 2=2=0pt = cmr5 _
the piece of _ nestor _ vacuum chamber with the ceramic insertion for dc - monitor and rf - shields was simulated by using both transient and wake field solvers of cst studio suite@xmath0. for a @xmath1 gap between two rf - shields the contributions of the assembly considered to the longitudinal broadband ( bb ) impedance @xmath2 and the loss factor @xmath3 are @xmath4 and @xmath5, correspondingly.   these estimates are the second largest after those of the rf - cavity that were obtained till now for the _ nestor _ ring components  .    contributions from a beam position monitor ( bpm ) are also obtained by simulation and compared with analytical estimates obtained earlier.   we also present in the paper the frequency content of longitudinal impedance in the frequency range from 0 to 16 ghz for all ring components considered.
we examine aspects of primordial star formation in the presence of a molecular hydrogen - dissociating ultraviolet background.   we compare a set of amr hydrodynamic cosmological simulations using a single cosmological realization but with a range of ultraviolet background strengths in the lyman - werner band.   this allows us to study the effects of lyman - werner radiation on suppressing 2 cooling at low densities as well as the high - density evolution of the collapsing cloud core in a self - consistent cosmological framework.   we find that the addition of a photodissociating background results in a delay of the collapse of high density gas at the center of the most massive halo in the simulation and, as a result, an increase in the virial mass of this halo at the onset of baryon collapse.   we find that, contrary to previous results, population iii star formation is not suppressed for j@xmath0, but occurs even with backgrounds as high as j@xmath1.   we find that 2 cooling leads to collapse despite the depressed core molecular hydrogen fractions due to the elevated 2 cooling rates at @xmath2 k. we observe a relationship between the strength of the photodissociating background and the rate of accretion onto the evolving protostellar cloud core, with higher lw background fluxes resulting in higher accretion rates. finally, we find that the collapsing cloud cores in our simulations do not fragment at densities below @xmath3  @xmath4 regardless of the strength of the lw background, suggesting that population iii stars forming in halos with t@xmath5  k may still form in isolation.
since the first detection of intracluster planetary nebulae in 1996, imaging and spectroscopic surveys identified such stars to trace the radial extent and the kinematics of diffuse light in clusters.   this topic of research is tightly linked with the studies of galaxy formation and evolution in dense environment, as the spatial distribution and kinematics of planetary nebulae in the outermost regions of galaxies and in the cluster cores is relevant for setting constraints on cosmological simulations. in this sense,   extragalactic planetary nebulae play a very important role in the near - field cosmology, in order to measure the integrated mass as function of radius and the orbital distribution of stars in structures placed in the densest regions of the nearby universe.
it is shown that randall - sundrum model has the edm term which violates the cp - symmetry. the comparison with the case of kaluza - klein theory   is done. the chiral property, localization, anomaly phenomena are examined.   we evaluate the bulk quantum effect using the method of the induced effective action.   this is a new origin of the cp - violation.   = cmr5 # 1#1^^    # 1
the standard - model higgs boson with mass @xmath0 decays almost exclusively to pairs of @xmath1 and @xmath2 bosons.   we calculate the dominant two - loop corrections, of @xmath3, to the partial widths of these decays. in the on - mass - shell renormalization scheme  , the correction factor is found to be @xmath4, where the second term is the one - loop correction.   we give full analytic results for all divergent two - loop feynman diagrams.   a subset of finite two - loop vertex diagrams is computed to high precision using numerical techniques.   we find agreement with a previous numerical analysis.   the above correction factor is also in line with a recent lattice calculation.   pacs numbers : 12.15.lk, 14.70.fm, 14.70.hp, 14.80.bn    16.cm 22.cm     @=11 tempcntc citex#2@fileswauxout tempcnta@tempcntb@neciteaciteforciteb:=#2citeo#1 citeotempcnta > tempcntbciteacitea, tempcnta = tempcntbtempcnta
we propose a cavity qed scheme based on the tavis - cummings model to realize a conditional, non - linear dynamics exhibiting complex chaos in an ensemble of two - level atoms.   the atoms interact pairwise with the coherent cavity field, which is subjected to homodyne measurement after the interaction.   one member of the pair of atoms is then measured and upon condition that it is found in its ground state the other member of the pair is kept, otherwise discarded.   the quantum state of the resulting ensemble of atoms is related to the state of the original ensemble via a non - linear transformation. by iterating this process with the help of an optical conveyor belt, for example,   one arrives at complex deterministic chaos, where the evolution of pure quantum states is sensitive to the initial conditions.   we uncover basic features of this dynamics by exploring stability regions in the space of initial states and analyze the occurrence of stable periodic orbits in dependence of the parameters of the model.   it is demonstrated that sensitivity to initial conditions can be applied to amplify small differences of quantum states.
we calculate the subjet rates for jets produced in hadron collisions.   the @xmath0 algorithm is used to define the jets and allows the theoretical calculation to sum both the leading and next - to - leading logarithms in the resolution variable, @xmath1.   we also ensure that our calculation matches exactly the leading order in @xmath2 result and has sensible behaviour near thresholds.    cern   th/99239 + ral  tr1999049 + mc  th99/10 + august 1999 +     +    j.r.  forshaw@xmath3 and m.h.   seymour@xmath4    @xmath3 theory division, cern, + 1211 geneva 23, switzerland.   + @xmath4 particle physics department, + rutherford appleton laboratory, + chilton, didcot, oxon.   ox11 0qx.   england.
the wave  structure of moving electrons is analyzed on a fundamental level by employing a modified de broglie relation. formalizing the wave   function @xmath0 in real notation yields internal energy components due to mass oscillations.   the wave  features can then be referred to physical waves of discrete frequency @xmath1 and the classical dispersion relation @xmath2, complying with the classical wave equation. including external potentials yields the schrdinger equation, which, in this context, is arbitrary due to the internal energy components.   it can be established that the uncertainty relations are an expression of this, fundamental, arbitrariness.   electrons and photons can be described by an identical formalism, providing formulations equivalent to the maxwell equations.   the wave equations of intrinsic particle properties are lorentz invariant considering total energy of particles, although transformations into a moving reference frame lead to an increase of intrinsic potentials. interactions of photons and electrons are treated extensively, the results achieved are equivalent to the results in quantum theory.   electrostatic interactions provide, a posteriori, a justification for the initial assumption of electron  wave stability : the stability of electron waves can be referred to vanishing intrinsic fields of interaction.   the concept finally allows the conclusion that a significant correlation for a pair of spin particles in epr  like measurements is likely to violate the uncertainty relations.    #
in the paper a possibility of metallic ferromagnetic state realization in a generalized hubbard model with more complete accounting of electron - electron interactions, in particular, the correlated hopping and exchange interaction integrals is investigated.   recently obtained by means of mean - field approximation single electron energy spectrum is used for the description of finite temperature properties of the system. in the paper the expression for the critical temperature of ferromagnet - paramagnet transition is found, the behaviour of temperature dependencies of magnetization and paramagnetic susceptibility is analyzed.   taking into account the correlated hopping allows to explain some peculiarity of ferromagnetic behaviour of transition metals, their alloys and compounds.   pacs number(s ) : 71.10.fd, 71.30.+h, 71.27.+a    -1.5 cm
we show that in some regions of supersymmetric parameter space, cp violating effects that mix the cp - even and cp - odd higgs bosons can enhance the neutralino annihilation rate, and hence the indirect detection rate of neutralino dark matter, by factors of @xmath0.   the same cp violating effects can reduce the neutralino scattering rate off nucleons, and hence the direct detection rate of neutralino dark matter, by factors of @xmath1.   we study the dependence of these effects on the phase of the trilinear coupling @xmath2, and find cases in the region being probed by dark matter searches which are experimentally excluded when cp is conserved but are allowed when cp is violated.
we study einstein static universes in the context of generic @xmath0 models.   it is shown that einstein static solutions exist for a wide variety of modified gravity models sourced by a barotropic perfect fluid with equation of state @xmath1, but these solutions are always unstable to either homogeneous or inhomogeneous perturbations.   our general results are in agreement with specific models investigated in that past.   we also discuss how our techniques can be applied to other scenarios in @xmath0 gravity.
the dynamics of tripartite entanglement of fermionic system in noninertial frames through linear contraction criterion when one or two observers are accelerated is investigated. in one observer accelerated case   the entanglement measurement is not invariant with respect to the partial realignment of different subsystems and for two observers accelerated case it is invariant.   it is shown that the acceleration of the frame does not generate entanglement in any bipartite subsystems. unlike the bipartite states, the genuine tripartite entanglement does not completely vanish in both one observer accelerated and two observers accelerated cases even in the limit of infinite acceleration.   the degradation of tripartite entanglement is fast when two observers are accelerated than when one observer is accelerated.   it is shown that tripartite entanglement is a better resource for quantum information processing than the bipartite entanglement in noninertial frames.pacs : 03.65.ud ; 03.67.mn;04.70.dy    keywords : tripartite entanglement ; noninertial frames.
fundamental forces of nature are described by field theories, also known as gauge theories, based on a local gauge invariance.   the simplest of them is quantum electrodynamics ( qed ), which is an example of an abelian gauge theory.   such theories describe the dynamics of massless photons and their coupling to matter.   however, in two spatial dimension ( 2d ) they are known to exhibit gapped phases at low temperature. in the realm of quantum spin systems, it remains a subject of considerable debate if their low energy physics can be described by emergent gauge degrees of freedom.   here we present a class of simple two - dimensional models that admit a low energy description in terms of an abelian gauge theory.   we find rich phase diagrams for these models comprising exotic deconfined phases and gapless phases - a rare example for 2d abelian gauge theories.   the counter - intuitive presence of gapless phases in 2d results from the emergence of additional symmetry in the models.   moreover, we propose schemes to realize our model with current experiments using ultracold bosonic atoms in optical lattices
a formalism for studying heavy quarks in terms of model dyson - schwinger equations is developed.   the formalism is the natural extension of a technique which has proved successful in a number of studies of light hadron physics.   the dressed heavy quark propagator, calculated to leading order in the inverse quark mass, is incorporated in a treatment of mesons consisting of a heavy quark and light antiquark via the ladder approximation bethe - salpeter equation. in the limit of infinite heavy quark mass the model   is found to respect the spectrum degeneracies present in heavy quark effective theory.   an exploratory numerical analysis of a simple form of the model is carried out to assess its viability for studying @xmath0 and @xmath1 mesons.
we first describe a reduction from the problem of lower - bounding the number of distinct distances determined by a set @xmath0 of @xmath1 points in the plane to an incidence problem between points and a certain class of helices ( or parabolas ) in three dimensions.   we offer conjectures involving the new setup, but are still unable to fully resolve them.    instead, we adapt the recent new algebraic analysis technique of guth and katz  @xcite, as further developed by elekes et al.   @xcite, to obtain sharp bounds on the number of incidences between these helices or parabolas and points in @xmath2. applying these bounds  , we obtain, among several other results, the upper bound @xmath3 on the number of rotations ( rigid motions ) which map ( at least ) three points of @xmath0 to three other points of @xmath0.   in fact, we show that the number of such rotations which map at least @xmath4 points of @xmath0 to @xmath5 other points of @xmath0 is close to @xmath6  .    one of our unresolved conjectures is that this number is @xmath7, for @xmath8.   if true, it would imply the lower bound @xmath9 on the number of distinct distances in the plane.   = 10
we investigate the slip boundary condition for single - phase flow past a chemically patterned surface.   molecular dynamics ( md ) simulations show that modulation of fluid - solid interaction along a chemically patterned surface induces a lateral structure in the fluid molecular organization near the surface. consequently,   various forces and stresses in the fluid vary along the patterned surface. given the presence of these lateral variations  , a general scheme is developed to extract hydrodynamic information from md data. with the help of this scheme,   the validity of the navier slip boundary condition is verified for the chemically patterned surface, where a local slip length can be defined.   based on the md results, a continuum hydrodynamic model is formulated using the navier - stokes equation and the navier boundary condition, with a slip length varying along the patterned surface.   steady - state velocity fields from continuum calculations are in quantitative agreement with those from md simulations.   it is shown that, when the pattern period is sufficiently small, the solid surface appears to be homogeneous, with an effective slip length that can be controlled by surface patterning.   such a tunable slip length may have important applications in nanofluidics.   * hydrodynamic slip boundary condition at chemically patterned surfaces : a continuum deduction from molecular dynamics *
we use distance measurements in the nearby universe to carry out new tests of gravity, surpassing other astrophysical tests by over two orders of magnitude for chameleon theories.   the three nearby distance indicators  cepheids, tip of the red giant branch ( trgb ) stars, and water masers  operate in gravitational fields of widely different strengths.   this enables tests of scalar - tensor gravity theories because they are screened from enhanced forces to different extents.   inferred distances from cepheids and trgb stars are altered ( in opposite directions ) over a range of chameleon gravity theory parameters well below the sensitivity of cosmological probes. using published data we have compared cepheid and trgb distances in a sample of unscreened dwarf galaxies within 10 mpc.   as a control sample we use a comparable set of screened galaxies.   we find no evidence for the order unity force enhancements expected in these theories.   using a two - parameter description of the models ( the coupling strength and background field value ) we obtain constraints on both the chameleon and symmetron screening scenarios.   in particular we show that @xmath0 models with background field values @xmath1 above @xmath2 are ruled out at the 95% confidence level.   we also compare trgb and maser distances to the galaxy ngc 4258 as a second test for larger field values. while there are several approximations and caveats in our study,   our analysis demonstrates the power of gravity tests in the local universe.   we discuss the prospects for additional, improved tests with future observations.
the results are presented of an extensive programme of optical and infrared imaging of radio sources in a complete subsample of the leiden  berkeley deep survey.   the lbds hercules sample consists of 72 sources observed at 1.4  ghz, with flux densities @xmath0  mjy, in a 1.2 deg@xmath1 region of hercules.   this sample is almost completely identified in the @xmath2, @xmath3, @xmath4 and @xmath5 bands, with some additional data available at @xmath6 and @xmath7.   the magnitude distributions peak at @xmath8  mag, @xmath9  mag and extend down to @xmath10  mag, @xmath11  mag.   the @xmath5-band magnitude distributions for the radio galaxies and quasars are compared with those of other radio surveys. at @xmath12   jy, the @xmath5-band distribution does not change significantly with radio flux density.   the sources span a broad range of colours, with several being extremely red ( @xmath13 ).   although small, this is the most optically complete sample of millijansky radio sources available at 1.4  ghz, and is ideally suited to study the evolution of the radio luminosity function out to high redshifts.   # 1    *  *    # 1    = = = = = = = =    # 1 # 1 # 1 # 1 @mathgroup@group @mathgroup@normal@groupeurmn @mathgroup@bold@groupeurbn @mathgroup@group @mathgroup@normal@groupmsamn @mathgroup@bold@groupmsamn = `` 019 ='' 016 = `` 040 =
the formation of purely baryonic globular clusters with no gravitationally bound dark matter is still a theoretical challenge.   we show that these objects might form naturally whenever there is a relative stream velocity between baryons and dark matter.   the stream velocity causes a phase shift between linear modes of baryonic and dark matter perturbations, which translates to a spatial offset between the two components when they collapse. for a @xmath0 ( @xmath1 ) density fluctuation, baryonic clumps with masses in the range @xmath2  m@xmath3 ( @xmath4  m@xmath3 ) collapse outside the virial radii of their counterpart dark matter halos.   these objects could survive as long - lived dark matter - free objects and might conceivably become globular clusters.   in addition, their dark matter counterparts, which were deprived of gas, might become dark satellite galaxies.
about 3@xmath0 deviation from the standard model prediction of muon anomalous magnetic moment ( muon g-2 ) has been reported.   we consider new physics beyond the standard model which has new yukawa interactions with muon.   we compute new contributions to muon g-2 and corrections to electroweak observables, and show the consistent region of parameter space.   we find that in a simple model where the chirality flip of muon occurs only in the external muon line in one - loop muon g-2 diagrams, it is necessary to introduce the relatively large new yukawa coupling and the electroweak scale new particles. on the other hand, in a model where the chirality flip can occur in the internal fermion line of one loop muon g-2 diagrams  , we can obtain favorable g-2 contributions without large yukawa coupling, and they are consistent with the precision electroweak observables. finally, we discuss effects of new particles for muon g-2 on the higgs boson decay @xmath1 and direct productions of these particles at the lhc experiment.   # 1   .75 in     * new physics for muon anomalous magnetic moment and its electroweak precision analysis *.75 in    @xmath2shunichi kanemitsu and @xmath3kazuhiro tobe    0.25 in    _ @xmath2department of physics, nagoya university, nagoya 464 - 8602, japan _    _ @xmath4kobayashi - maskawa institute for the origin of particles and the universe, + nagoya university, nagoya 464 - 8602, japan _  .5 in
x - ray spectroscopy of seyfert 1 galaxies often reveal absorption edges resulting from photoionized gas along the line - of - sight to the central engine, the so - called warm absorber.   i discuss how recent _ asca _ observations of warm absorber variability in mcg@xmath06 - 30 - 15 can lead us to reject a one - zone model and, instead, have suggested a multi - zone warm absorber. the evidence for dust within the warm absorbers of mcg@xmath06 - 30 - 15 and iras   13349 + 2438 is also addressed.   these dusty warm absorbers reveal themselves by significantly reddening the optical flux without heavily absorbing the soft x - ray photons.   thermal emission from this warm / hot dust may be responsible for the infra - red bump commonly seen in the broad band spectrum of many seyfert galaxies.
we propose various improvements of finite step - size updating for full qcd on the lattice that might turn finite step - size updating into a viable alternative to the hybrid monte carlo algorithm.   these improvements are noise reduction of the noisy estimator of the fermion determinant, unbiased inclusion of the hopping parameter expansion and a multi - level metropolis scheme.   first numerical tests are performed for the 2 dimensional schwinger model with two flavours of wilson fermions and for qcd with two flavours of wilson fermions and schrdinger functional boundary conditions. 0.1 cm    -4 mm    hub - ep-98/41 +    * speeding up finite step - size updating of full qcd on the lattice *    0.8 cm    m. hasenbusch   .2 cm    _ humboldt universitt zu berlin, institut fr physik _   _ invalidenstr.   110, d-10115 berlin, germany _    0.6 cm
physical consequences from gravitation equations based on poincar ideas of relativity of space and time in respect of measuring instruments are considered.   the most interesting of them are the possibility of the existence of stable supermassive configurations @xmath0 which can exist in galactic centres, and an explanation of the acceleration of the universe expansion as a manifestation of the gravitational force properties in the theory under consideration.    
the angular correlation function of the background shear - foreground galaxy distribution probes the three dimensional cross power spectrum between mass and galaxies.   the same cross power spectrum is also probed when foreground galaxy distribution is cross - correlated with a distribution of background sources disjoint in redshift space.   the kernels that project three dimensional clustering to the two dimensional angular space is different for these two probes. when combined, they allow a study of the galaxy - mass cross power spectrum from linear to non - linear scales. by inverting the background shear - foreground galaxy correlation function measured by the sloan digital sky survey, we present a first estimate of the cross power spectrum between mass and galaxies at low redshifts.   cosmology : observations  gravitational lensing
we study the definition of perturbations in the presence of a submanifold, like e.g.  a brane. in the standard theory of cosmological perturbations,   one compares quantities at the same _ coordinate points _ in the non - perturbed and the perturbed manifolds, identified via a ( non - unique ) mapping between the two manifolds. in the presence of a physical submanifold one needs to modify this definition in order to evaluate perturbations of quantities at the submanifold location. as an application  , we compute the perturbed metric and the extrinsic curvature tensors at the brane position in a general gauge.
we study the pathologies in ads black branes in lovelock theory.   more precisely, we examine the conditions that ads black branes have the naked singularity, the ghost instability and the dynamical instability. from the point of view of the ads / cft correspondence, the pathologies in ads black branes indicate the pathologies in the corresponding cft.   hence, we need to be careful when we apply ads / cft in lovelock theory to various phenomena such as the shear viscosity to entropy ratio in strongly coupled quantum filed theory.
the position of a lander on mars surface is affected by different motions : the nutations, the precession, the length - of - day variations and the polar motion.   we derive first - order expressions of the signature of these different rotation parameters in a doppler observable between a lander and the earth.   these expressions are function of the diurnal rotation of mars, the lander position, the planet radius and the rotation parameter.   the nutation signature is proportional to the earth declination with respect to mars.   + for an equatorial lander on mars, the largest signatures in the doppler observable are for the length - of - day variations, precession rate and rigid nutations. the polar motion and the liquid core signatures have a much smaller amplitude. for a lander closer to the pole,   the polar motion signature is enhanced while the other signatures decrease.   + similarly, we derive expressions for the signatures of the rotation parameters in the lander - earth range observable.   + these expressions are useful in order to find when these signatures are maximal during one day or on a longer timescale, therefore to identify the best times to observe with a geodesy experiment, like the ones on - board the future insight or exomars2020 missions.   + we numerically evaluate the amplitudes of the rotation parameters signature in the doppler observable for landers on other planets or moons.
we use theoretical period - luminosity and period - luminosity - color relations in the @xmath0 passbands, as based on nonlinear, nonlocal and time - dependent convective pulsating models, to predict the reddening and true distance modulus of distant cepheids observed with the hubble space telescope. by relying on the pulsating models with metal content @xmath1=0.008  , we find that the theoretical predictions agree to the values obtained by the extragalactic distance scale key project on the basis of empirical period - luminosity relations referenced to lmc variables. in the meantime, from the theoretical relations with @xmath1=0.004 and 0.02 we find that the predicted @xmath2 and @xmath3 decrease as the adopted metal content increases.   this suggests a metallicity correction to lmc - based distances as given by @xmath4/@xmath50.27 mag dex@xmath6, where @xmath7 is the difference between the metallicity of the cepheids whose distance we are estimating and the lmc value @xmath1=0.008. such a theoretical correction appears supported by an existing, although weak, correlation between the cepheid distance and the  metallicity of galaxies within a given group or cluster, as well as by a similar correlation between the @xmath8 estimate and the  metallicity of the galaxies which calibrate the snia luminosity. on the contrary,   the metallicity correction earlier suggested on empirical grounds seem to be excluded.   eventually we suggest that the average value @xmath9 67 km s@xmath6 mpc@xmath6 provided by the key project team should increase _ at least _ up to @xmath10 69 km s@xmath6 mpc@xmath6. further observational evid
quantum interference between one- and two - photon absorption pathways allows coherent control of interband transitions in unbiased bulk semiconductors ; carrier population, carrier spin polarization, photocurrent injection, and spin current injection may all be controlled.   we extend the theory of these processes to include the electron - hole interaction.   our focus is on photon energies that excite carriers above the band edge, but close enough to it so that transition amplitudes based on low order expansions in @xmath0 are applicable ; both allowed - allowed and allowed - forbidden two - photon transition amplitudes are included.   analytic solutions are obtained using the effective mass theory of wannier excitons ; degenerate bands are accounted for, but envelope - hole coupling is neglected.   we find a coulomb enhancement of two - color coherent control process, and relate it to the coulomb enhancements of one- and two - photon absorption.   in addition, we find a frequency dependent phase shift in the dependence of photocurrent and spin current on the optical phases.   the phase shift decreases monotonically from @xmath1 at the band edge to @xmath2 over an energy range governed by the exciton binding energy.   it is the difference between the partial wave phase shifts of the electron - hole envelope function reached by one- and two - photon pathways.
this review aims to give a summary of our understanding of galaxy evolution as infered from studies of nearby galaxies ; how observations made with the _ hubble space telescope _ have contributed significantly to our detailed understanding of the older stellar populations in local group dwarf galaxies.   recent results from vlt are also promising interesting future prospects for the study of resolved stellar populations in nearby dwarf galaxies.   = 23.5 cm = 16.5 cm = 0.46 cm = 0.pt = 0.pt = -0.54 cm = -0.54 cm    ps.   @plainmkbothoddheadoddfoot``dwarf galaxies and their environment '' ; international conference in bad honnef, germany, 23 - 27 january 2001evenheadevenfootoddfoot
the photometric and spectroscopic observational campaign organized for the 2008/9 eclipse of ee  cep revealed features, which indicate that the eclipsing disk in the ee  cep system has a multi - ring structure.   we suggest that the gaps in the disk can be related to the possible planet formation.
the casimir energy corresponding to a massive scalar field with dirichlet boundary conditions on a spherical bag is obtained.   the field is considered, separately, inside and outside the bag.   the renormalization procedure that is necessary to apply in each situation is studied in detail, in particular the differences occurring with respect to the case when the field occupies the whole space.   the final result contains several constants that experience renormalization and can be determined only experimentally.   the non - trivial finite parts that appear in the massive case are found exactly, providing a precise determination of the complete, renormalized zero - point energy for the first time.   -0.5 in    pacs : 02.30.+g, 02.40.+m + hep - th/9608071 +
we present results for entropy and kinetic energy spectra computed from direct numerical simulations for low - prandtl - number ( @xmath0 ) turbulent flow in rayleigh - bnard convection with uniform rotation about a vertical axis.   the simulations are performed in a three - dimensional periodic box for a range of taylor number ( @xmath1 ) and reduced rayleigh number @xmath2 ( @xmath3 ).   the rossby number @xmath4 varies in the range @xmath5.   the entropy spectrum @xmath6 shows bi - splitting into two branches for lower values of wave number @xmath7.   the entropy in the lower branch scales with @xmath7 as @xmath8 for @xmath9 for the rotation rates considered here.   the entropy in the upper branch also shows scaling behavior with @xmath7, but the scaling exponent decreases with increasing @xmath10 for all @xmath11.   the energy spectrum @xmath12 is also found to scale with the wave number @xmath7 as @xmath8 for @xmath9.   the scaling exponent for the energy spectrum and the lower branch of the entropy spectrum vary between @xmath13 to @xmath14 for lower values of @xmath11 ( @xmath15 ).   we also provide some simple arguments based on the variation of the kolmogorov picture to support the results of simulations.
this talk briefly explains how the breaking of a lorentz - invariant description of nature at tiny space - time intervals might affect the non - gaussian character of the primordial fluctuations left by inflation.   for example, a model that contains irrelevant operators that only preserve the spatial symmetries along constant - time surfaces can generate a larger non - gaussian component in the pattern of primordial fluctuations than is ordinarily predicted by inflation.   this property can be useful for constraining models that allow some lorentz violation at short distances, beyond the constraints possible from the power spectrum alone.   address = the niels bohr international academy, the niels bohr institute, 2100 copenhagen , denmark
in this paper we present the results on raman - active modes calculation in achiral @xmath0 and @xmath1 carbon nanotubes ( cnts ).   vibrational spectra are derived as the eigenvalues of corresponding dynamical matrix at the @xmath2-point of brillouin zone.   diagonal components and @xmath3 are the only non - zero components of polarization tensor. selection rules for raman - active modes are determined by direct estimations of matrix elements responsible for the intensities of corresponding vibrational transitions.   few @xmath4 modes can be non - raman - active because of their `` fine '' vibrational structure.   we claim that numbers of raman - active modes for achiral cnts are : 5 ( @xmath0 and @xmath1, @xmath5-even ) ; 6 ( @xmath0, @xmath5-odd ) ; 8 ( @xmath1, @xmath5-odd ).    9.5 in 6.4 in
we present the results of monte carlo simulations of the magnetic properties of a model for a single nanoparticle consisting in a ferromagnetic core surrounded by an antiferromagnetic shell.   the simulations of hysteresis loops after cooling in a magnetic field display exchange bias effects. in order to understand the origin of the loop shifts,   we have studied the thermal dependence of the shell and interface magnetizations under field cooling.   these results, together with inspection of the snapshots of the configurations attained at low temperature, show the existence of a net magnetization at the interface which is responsible for the bias of the hysteresis loops.    and    monte carlo simulation, nanoparticles, hysteresis, exchange bias
we assume that nucleon antinucleon annihilation is a fast process leading to a classical coherent pion pulse.   we develop the quantum description of such pion waves based on the method of coherent states.   we study the consequences of such a description for averages of charge types and moments of distributions of pion momenta with iso - spin and four - momentum conservation taken into account.   we briefly discuss the applicability of our method to annihilation at rest, where we find agreement with experiment, and suggest other avenues for its use.
the steady states of three families of one - dimensional non - equilibrium models with open boundaries, first proposed in @xcite, are studied using a matrix product formalism.   it is shown that their associated quadratic algebras have two - dimensional representations, provided that the transition rates lie on specific manifolds of parameters.   exact expressions for the correlation functions of each model have also been obtained.   we have also studied the steady state properties of one of these models, first introduced in @xcite, with more details. by introducing a canonical ensemble   we calculate the canonical partition function of this model exactly. using the yang - lee theory of phase transitions   we spot a second - order phase transition from a power - law to a jammed phase.   the density profile of particles in each phase has also been studied.   a simple generalization of this model in which both the left and the right boundaries are open has also been introduced.   it is shown that double shock structures may evolve in the system under certain conditions.
we construct brst invariant solitonic states in the @xmath0 invariant string field theory for closed bosonic strings.   our construction is a generalization of the one given in the noncritical case.   these states are made by using the boundary states for d - branes, and can be regarded as states in which d - branes or ghost d - branes are excited.   we calculate the vacuum amplitude in the presence of solitons perturbatively and show that the cylinder amplitude for the d - brane is reproduced.   the results imply that these are states with even number of d - branes or ghost d - branes.        * d - branes and closed string field theory *    yutaka baba@xmath1, nobuyuki ishibashi@xmath1, koichi murakami@xmath2    @xmath1_institute of physics, university of tsukuba, + tsukuba, ibaraki 305 - 8571, japan _   +    @xmath2_center for computational sciences, university of tsukuba, + tsukuba, ibaraki 305 - 8577, japan _
a formalism is presented for treating strongly - correlated graphene quantum hall states in terms of an so(8 ) fermion dynamical symmetry that includes pairing as well as particle   hole generators.   the graphene so(8 ) algebra is isomorphic to an so(8 ) algebra that has found broad application in nuclear physics, albeit with physically very different generators, and exhibits a strong formal similarity to su(4 ) symmetries that have been proposed to describe high - temperature superconductors.   the well - known su(4 ) symmetry of quantum hall ferromagnetism for single - layer graphene is recovered as one subgroup of so(8 ), but the dynamical symmetry structure associated with the full set of so(8 ) subgroup chains extends quantum hall ferromagnetism and allows analytical many - body solutions for a rich set of collective states exhibiting spontaneously - broken symmetry that may be important for the low - energy physics of graphene in strong magnetic fields.   the so(8 ) symmetry permits a natural definition of generalized coherent states that correspond to symmetry - constrained hartree  fock  bogoliubov solutions, or equivalently a microscopically - derived ginzburg   landau formalism, exhibiting the interplay between competing spontaneously broken symmetries in determining the ground state.
we present both the observations and the data reduction procedures of the subaru cosmos 20 project that is an optical imaging survey of the _ hst _ cosmos field, carried out by using suprime - cam on the subaru telescope with the following 20 optical filters : 6 broad - band ( @xmath0, @xmath1, @xmath2, @xmath3, @xmath4, and @xmath5 ), 2 narrow - band ( nb711 and nb816 ), and 12 intermediate - band filters ( ia427, ia464, ia484, ia505, ia527, ia574, ia624, ia679, ia709, ia738, ia767, and ia82726.   an intermediate - band filter would be abbreviated as ib.   however, since this intermediate - band filter systems is the first such custom filter series, this filter system is named as ia by the subaru telescope office. ] ). a part of this project is described in taniguchi et al.   ( 2007 ) and capak et al.   ( 2007 ) for the six broad - band and one narrow - band ( nb816 ) filter data. in this paper  , we present details of the observations and data reduction for remaining 13 filters ( the 12 ia filters and nb711 ).   in particular, we describe the accuracy of both photometry and astrometry in all the filter bands.   we also present optical properties of the suprime - cam ia filter system in appendix.
we present mid - infrared images at @xmath0 and @xmath1 of `` the cartwheel '' ( am  0035 - 33 ), the prototypical collisional ring galaxy.   the observations, taken with isocam, reveal the distribution of hot dust in the galaxy and its two companions in the north - east.   the intensity of the mid - ir emission from the outer star forming ring of the cartwheel shows considerable azimuthal variation and peaks at the most active h@xmath2 region of the ring.   the 15@xmath3 to 6.7@xmath3 flux ratio of 5.2 is the highest among all the galaxies of our sample.   a surprising result of our observations is the discovery of significant emission from the inner regions of the galaxy, including the inner ring, spokes and nucleus, where previously only low level h@xmath2 emission had been reported. at 6.7@xmath3,   this emission is stronger than the one from the outer star forming ring, and at 15@xmath3, it represents 40% of the emission from the outer ring.   the h@xmath2 to mid - ir flux ratios from the inner regions are consistent with the heating of grains from weak star formation activity.
in this paper we study the effective thermal behaviour of 3d representative volume elements ( rves ) of two - phased composite materials constituted by a matrix with cylindrical and spherical inclusions distributed randomly, with periodic boundaries.   variations around the shape of inclusions have been taken into account, by corrugating shapes, excavating and/or by removing pieces of inclusions.   the effective behaviour is computed with the help of homogenization process based on an accelerated fft - scheme giving the thermal conductivity tensor.   several morphological parameters are also taken into account for instance the number and the volume fraction of each type of inclusions,... in order to analyse the behaviour of the composite for a large number of geometries.   we compare the results obtained for rves with and without variations, and then with the mechanical results of such composite studied in our previous paper.
we study the non - equilibrium behavior of the three - dimensional gaussian random - field ising model at @xmath0 in the presence of a uniform external field using a @xmath1-spin - flip dynamics.   the deterministic, history - dependent evolution of the system is compared with the one obtained with the standard @xmath2-spin - flip dynamics used in previous studies of the model.   the change in the dynamics yields a significant suppression of coercivity, but the distribution of avalanches ( in number and size ) stays remarkably similar, except for the largest ones that are responsible for the jump in the saturation magnetization curve at low disorder in the thermodynamic limit. by performing a finite - size scaling study  , we find strong evidence that the change in the dynamics does not modify the universality class of the disorder - induced phase transition.
weyl semimetals are three - dimensional topological states of matter, in a sense that they host paired monopoles and antimonopoles of berry curvature in momentum space, leading to the chiral anomaly.   the chiral anomaly has long been believed to give a positive magnetoconductivity or negative magnetoresistivity in strong and parallel fields. however, several recent experiments on both weyl and dirac topological semimetals show a negative magnetoconductivity in high fields. here, we study the magnetoconductivity of weyl and dirac semimetals in the presence of short - range scattering potentials. in a strong magnetic field   applied along the direction that connects two weyl nodes, we find that the conductivity along the field direction is determined by the fermi velocity, instead of by the landau degeneracy.   we identify three scenarios in which the high - field magnetoconductivity is negative.   our findings show that the high - field positive magnetoconductivity may not be a compelling signature of the chiral anomaly and will be helpful for interpreting the inconsistency in the recent experiments and earlier theories.
the ability of nicmos to perform high accuracy polarimetry is currently hampered by an uncalibrated residual instrumental polarization at a level of @xmath0. to better quantify and characterize this residual we obtained observations of three polarimetric standard stars at three separate space - craft roll angles.   combined with archival data, these observations were used to characterize the residual instrumental polarization to enable nicmos to reach its full polarimetric potential. using these data,   we calculate values of the parallel transmission coefficients that reproduce the ground - based results for the polarimetric standards.   the uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, dominate the accuracy of @xmath1 and @xmath2.   however, the new coefficients now enable imaging polarimetry of targets with @xmath3 at an accuracy of @xmath4 and @xmath5.
the second - order nonlinear optical susceptibility ( @xmath0 ) and linear electro - optical coefficient ( @xmath1 ) of a large number of single - walled zigzag, armchair and chiral sic nanotubes ( sic - nts ) as well as bulk sic polytypes ( 2h-, 4h-, 6h- and 3c - sic ) and single graphitic sic sheet have been calculated from first - principles.   the calculations are based on density functional theory in the local density approximation and highly accurate full - potential projector augmented - wave method is used. both the zigzag and chiral sic - nts   are found to exhibit large second - order nonlinear optical behavior with the @xmath0 and @xmath1 coefficients being up to ten - times larger than that of bulk sic polytypes, and also being up to thirteen - times larger than the counterparts of the corresponding bn - nts, indicating that sic - nts are promising materials for nonlinear optical and opto - electric applications.   the prominant features in the spectra of @xmath2 of the sic - nts are correlated with the features in the linear optical dielectric function @xmath3 in terms of single - photon and two - photon resonances.
by combining osse, smm and tgrs observations of the galactic center region, purcell et al.   ( 1997 ) and cheng et al. ( 1997 ) produced the first maps of galactic positron annihilation.   that data - set has been augmented with additional data, both recent and archival, and re - analyzed to improve the spectral fitting.   the improved spectral fitting has enabled the first maps of positronium continuum emission and the most extensive maps of 511 kev line emission.   bulge and disk combinations have been compared with the 511 kev line data, demonstrating that extended bulges are favored over a gc point source for every disk model tested.   this result is independent of whether osse - only, osse / smm, or osse / smm / tgrs data - sets are used.   the estimated bulge to disk ratio ( and to a lesser extent the total flux ) is shown to be dependent upon the assumption of bulge shape. a positive latitude enhancement is shown to have an effect upon the b / d ratio, but this effect is secondary to the choice of bulge shape.
electron scattering on both neutral ( @xmath0 ) and charged ( @xmath1 ) excitons in quantum wells is studied theoretically.   a microscopic model is presented, taking into account both elastic and dissociating scattering.   the model is based on calculating the exciton - electron direct and exchange interaction matrix elements, from which we derive the exciton scattering rates.   we find that for an electron density of @xmath2 in a gaas qw at @xmath3, the @xmath1 linewidth due to electron scattering is roughly twice as large as that of the neutral exciton.   this reflects both the @xmath1 larger interaction matrix elements compared with those of @xmath0, and their different dependence on the transferred momentum.   calculated reflection spectra can then be obtained by considering the three electronic excitations of the system, namely, the heavy - hole and light - hole 1s neutral excitons, and the heavy - hole 1s charged exciton, with the appropriate oscillator strengths.
we observed the field of the _ fermi _  source 3fgl j0838.8@xmath02829  in optical and x - rays, initially motivated by the cataclysmic variable ( cv ) 1rxs j083842.1@xmath0282723that lies within its error circle.   several x - ray sources first classified as cvs have turned out to be @xmath1-ray emitting millisecond pulsars ( msps ).   we find that 1rxs j083842.1@xmath0282723  is in fact an unusual cv, a stream - fed asynchronous polar in which accretion switches between magnetic poles ( that are @xmath2 apart ) when the accretion rate is at minimum.   high - amplitude x - ray modulation at periods of and  are seen.   the former appears to be the spin period, while the latter is inferred to be one - third of the beat period between the spin and the orbit, implying an orbital period of.   we also measure an optical emission - line spectroscopic period of, which is consistent with the orbital period inferred from the x - rays. in any case, this system is unlikely to be the @xmath1-ray source. instead, we find a fainter variable x - ray and optical source, xmmu j083850.38@xmath0282756.8, that is modulated on a time scale of hours in addition to exhibiting occasional sharp flares.   it resembles the black widow or redback pulsars that have been discovered as counterparts of _ fermi _  sources, with the optical modulation due to heating of the photosphere of a low - mass companion star by, in this case, an as - yet undetected msp.   we propose xmmu j083850.38@xmath0282756.
recently, a number of authors have proposed decoding schemes for reed - solomon ( rs ) codes based on multiple trials of a simple rs decoding algorithm. in this paper  , we present a rate - distortion ( r - d ) approach to analyze these multiple - decoding algorithms for rs codes.   this approach is first used to understand the asymptotic performance - versus - complexity trade - off of multiple error - and - erasure decoding of rs codes. by defining an appropriate distortion measure between an error pattern and an erasure pattern, the condition for a single error - and - erasure decoding to succeed reduces to a form where the distortion is compared to a fixed threshold.   finding the best set of erasure patterns for multiple decoding trials then turns out to be a covering problem which can be solved asymptotically by rate - distortion theory.   next, this approach is extended to analyze multiple algebraic soft - decision ( asd ) decoding of rs codes.   both analytical and numerical computations of the r - d functions for the corresponding distortion measures are discussed.   simulation results show that proposed algorithms using this approach perform better than other algorithms with the same complexity.
we have observed a sample of 13 large, powerful fanaroff - riley type ii radio galaxies with the very large array ( vla ) in multiple configurations and at multiple frequencies.   we have combined our measurements of spectral indices, rotation measures and structural parameters such as arm - length ratios, axial ratios and misalignment angles, with similar data from the literature and revisited some well - known radio galaxy correlations.
the long - term variability of a sample of 149 optically selected qsos in the field of the selected area 94 has been studied in the r - band.   the relations between variability and luminosity and between variability and redshift have been investigated by means of `` robust '' statistical estimators, allowing to disentangle the effects of the measurement errors.   the results are compared with the corresponding properties of the variability in the b - band for the same sample.   an anti - correlation between the r - band variability and the intrinsic luminosity is found, analogously to what is observed in the b - band.   the amplitude of the r - band variability turns out to be smaller ( of a factor @xmath0 ) than the b - band variability.   the implications in terms of the black - hole, starburst and microlensing models are discussed.
spatially homogeneous cosmological models with a positive cosmological constant are investigated, using dynamical systems methods.   we focus on the future evolution of these models. in particular, we address the question whether there are models within this class that are de sitter - like in the future, but are tilted.
we present the line of sight radial velocity dispersion profile of the sextans dwarf spheroidal galaxy ( dsph ), based on a sample of 88 stars extending to about @xmath0 ( @xmath1kpc ). like the draco and ursa minor dsphs  , sextans shows some evidence of a fall - off in the velocity dispersion at large projected radii, with significance @xmath2.   surprisingly, the dispersion at the very centre of sextans is close to zero ( with significance @xmath2 ).   we present evidence which suggests that this latter change in the stellar kinematics coincides with changes in the stellar populations within the dsph.   we discuss possible scenarios which could lead to a kinematically and photometrically distinct population at the centre of sextans.   dark matter  galaxies : individual ( sextans dsph)galaxies : kinematics and dynamics  local group  stellar dynamics
the hypercentral constituent quark model ( hcqm ) for the baryon structure is reviewed and its applications are systematically discussed. the model is based on a simple form of the quark potential, which contains a coulomb - like interaction and a confinement, both expressed in terms of a collective space coordinate, the hyperradius.   the model has only three free parameters, determined in order to describe the baryon spectrum.   once the parameters have been fixed, the model, in its non relativistic version, is used to predict various quantities of physical interest, namely the elastic nucleon form factors, the photocouplings and the helicity amplitudes for the electromagnetic excitation of the baryon resonances. in particular  , the @xmath0 dependence of the helicity amplitude is quite well reproduced, thanks to the coulomb - like interaction.   the model is reformulated in a relativistic version by means of the point form hamilton dynamics. while the inclusion of relativity does not alter the results for the helicity amplitudes, a good description of the nucleon elastic form factors is obtained.
in this work, we study the problem of aggregating a finite number of predictors for nonstationary sub - linear processes.   we provide oracle inequalities relying essentially on three ingredients : ( 1 )  a uniform bound of the @xmath0 norm of the time varying sub - linear coefficients, ( 2 )  a lipschitz assumption on the predictors and ( 3 )  moment conditions on the noise appearing in the linear representation.   two kinds of aggregations are considered giving rise to different moment conditions on the noise and more or less sharp oracle inequalities.   we apply this approach for deriving an adaptive predictor for locally stationary time varying autoregressive ( tvar ) processes.   it is obtained by aggregating a finite number of well chosen predictors, each of them enjoying an optimal minimax convergence rate under specific smoothness conditions on the tvar coefficients.   we show that the obtained aggregated predictor achieves a minimax rate while adapting to the unknown smoothness. to prove this result, a lower bound   is established for the minimax rate of the prediction risk for the tvar process.   numerical experiments complete this study.   an important feature of this approach is that the aggregated predictor can be computed recursively and is thus applicable in an online prediction context.  ./style / arxiv - general.cfg   ,     +
we have studied the filaments extracted from the column density maps of the nearby lupus 1, 3, and 4 molecular clouds, derived from photometric maps observed with the _ herschel _ satellite.   filaments in the lupus clouds have quite low column densities, with a median value of @xmath01.5@xmath110@xmath2 @xmath3 and most have masses per unit length lower than the maximum critical value for radial gravitational collapse.   indeed, no evidence of filament contraction has been seen in the gas kinematics.   we find that some filaments, that on average are thermally subcritical, contain dense cores that may eventually form stars.   this is an indication that in the low column density regime, the critical condition for the formation of stars may be reached only locally and this condition is not a global property of the filament. finally,   in lupus we find multiple observational evidences of the key role that the magnetic field plays in forming filaments, and determining their confinement and dynamical evolution.       ism : clouds  stars : formation.
the rastall s theory is a modification of general relativity touching one of the cornestone of gravity theory : the conservation laws. in rastall   s theory, the energy - momentum tensor is not conserved anymore, depending now on the gradient of the ricci curvature. in this sense, this theory can be seen as a classical implementation of quantum effects in a curved background space - time.   we exploit this structure in order to reproduce some results of an effective theory of quantum loop cosmology.   later, we propose a model for the dark sector of the universe. in this case  , the corresponding @xmath0cdm model appears as the only model consistent with observational data.
a kinetic monte carlo ( kmc ) method is used to study the structural properties and dynamics of a supercooled binary lennard - jones liquid around the glass transition temperature.   this technique permits us to explore the potential energy surface and barrier distributions without suffering the exponential slowing down at low temperature that affects molecular dynamics simulations. in agreement with previous studies we observe a distinct change in behaviour around @xmath0, close to the dynamical transition temperature @xmath1 of mode coupling theory ( mct ).   below this temperature the number of different local minima visited by the system for the same number of kmc steps decreases by more than an order of magnitude.   the mean number of atoms involved in each jump between local minima and the average distance they move also decreases significantly, and new features appear in the partial structure factor. above @xmath2 the probability distribution for the magnitude of the atomic displacement per kmc step exhibits an exponential decay, which is only weakly temperature dependent.   ''' ''   ''' ''
we present the second in a series of results in which we have searched for undiscovered neutron stars in supernova remnants ( snrs ).   this paper deals with the largest six snrs in our sample, too large for _ chandra _  or _ xmm - newton _  to cover in a single pointing.   these snrs are nearby, with typical distances of @xmath0  kpc.   we therefore used the _ rosat _  bright source catalog and past observations in the literature to identify x - ray point sources in and near the snrs.   out of 54 sources, we were immediately able to identify optical / ir counterparts to 41 from existing data.   we obtained _ chandra _  snap - shot images of the remaining 13 sources.   of these, 10 were point sources with readily identified counterparts, two were extended, and one was not detected in the _ chandra _  observation but is likely a flare star.   one of the extended sources may be a pulsar wind nebula, but if so it is probably not associated with the nearby snr.   we are then left with no identified neutron stars in these six snrs down to luminosity limits of @xmath1.   these limits are generally less than the luminosities of typical neutron stars of the same ages, but are compatible with some lower - luminosity sources such as the neutron stars in the snrs cta  1 and ic  443.
we investigate how large lepton asymmetries affect the evolution of the early universe at times before big bang nucleosynthesis and in particular how they influence the relic density of wimp dark matter. in comparison to the standard calculation of the relic wimp abundance   we find a decrease, depending on the lepton flavour asymmetry.   we find an effect of up to 20 per cent for lepton flavour asymmetries @xmath0.   _ keywords _ : early universe ; dark matter;wimps ; neutrinos ;
the importance of hst for the study of quasar absorption lines and of the nature of the intergalactic medium is illustrated by reviewing selected results from past hst observations.   topics reviewed include the study of ly@xmath0 absorbers at low redshift and the search for a diffuse igm at high redshifts.
we present a hybrid model of the unitary - evolution - based quantum computation model and the measurement - based quantum computation model. in the hybrid model part of a quantum circuit   is simulated by unitary evolution and the rest by measurements on star graph states, thereby combining the advantages of the two standard quantum computation models. in the hybrid model,   a complicated unitary gate under simulation is decomposed in terms of a sequence of single - qubit operations, the controlled-@xmath0 gates, and multi - qubit rotations around the @xmath1-axis.   every single - qubit- and the controlled-@xmath0 gate are realized by a respective unitary evolution, and every multi - qubit rotation is executed by a single measurement on a required star graph state.   the classical information processing in our model only needs an information flow vector and propagation matrices.   we provide the implementation of multi - control gates in the hybrid model.   they are very useful for implementing grover s search algorithm, which is studied as an illustrating example.
photons can carry spin angular momentum ( sam ) and orbital angular momentum ( oam ), which can be used to realize a qubit system and a high - dimension system respectively.   this spin - orbital system is very suitable for implementing one - dimensional discrete - time quantum random walks.   we propose a simple scheme of quantum walks on the spin - orbital angular momentum space of photons, where photons walk on the infinity oam space controlled by their sam. by employing the recent invention of an optical device, the so - called q - plate,   our scheme is more simple and efficient than others because there is no mach - zehnder interferometer in the scheme.
we present the australia telescope compact array ( atca ) observations of the sio masers in the galactic center in transitions of v=1, j=21 at 86  ghz and v=1, j=10 at 43  ghz.   two 86-ghz sio masers were detected within the central parsec, and they are associated with irs 10ee and irs 15ne, respectively.   we detected eighteen 43-ghz sio masers within a projected separation of @xmath02 pc from sagittarius a * ( sgr a * ), among which seven masers are newly discovered from our observations.   this raises the total number of 43-ghz sio masers within the central 4 parsecs of the gc region to 22.   simultaneous observations at 86 and 43  ghz showed that the intensity of 43-ghz sio maser is @xmath13 times higher than that of 86-ghz maser in irs 10ee ( an oh / ir star ), while the integrated flux of the sio maser emission at 43 ghz is comparable with that at 86  ghz in irs  15ne ( an ordinary mira variable ).   these results are consistent with previous observations of massive late - type stars in the galaxy in which the 86-ghz sio maser is in general weaker than the 43-ghz sio maser in oh / ir stars, while the two transitions are comparably strong in mira stars.
a method to construct integrable deformations of hamiltonian systems of odes endowed with lie   poisson symmetries is proposed by considering poisson  lie groups as deformations of lie  poisson ( co)algebras. moreover,   the underlying lie  poisson symmetry of the initial system of odes is used to construct integrable coupled systems, whose integrable deformations can be obtained through the construction of the appropriate poisson  lie groups that deform the initial symmetry.   the approach is applied in order to construct integrable deformations of both uncoupled and coupled versions of certain integrable types of rssler and lorenz systems.   it is worth stressing that such deformations are of non  polynomial type since they are obtained through an exponentiation process that gives rise to the poisson   lie group from its infinitesimal lie bialgebra structure.   the full deformation procedure is essentially algorithmic and can be computerized to a large extent.   ngel ballesteros@xmath0, alfonso blasco@xmath0 and fabio musso@xmath1    @xmath0__departamento de fsica, universidad de burgos, 09001 burgos, spain _ _    @xmath2__i.c.   leonardo da vinci ", via della grande muraglia 37, i-0014 rome, italy _ _    e - mail : angelb@ubu.es, ablasco@ubu.es, fmusso@ubu.es    msc : 37j35 ; 34a26 ; 34c14 ; 17b62 ; 17b63    keywords : integrability, deformations, ordinary differential equations, coupled systems, r
the magnitude of the spin polarization at the fermi level of ferromagnetic materials at room temperature is a key property for spintronics.   investigating the heusler compound co@xmath0mnsi a value of 93@xmath1 for the spin polarization has been observed at room temperature, where the high spin polarization is related to a stable surface resonance in the majority band extending deep into the bulk. in particular, we identified in our spectroscopical analysis that this surface resonance is embedded in the bulk continuum with a strong coupling to the majority bulk states.   the resonance behaves very bulk - like, as it extends over the first six atomic layers of the corresponding ( 001)-surface.   our study includes experimental investigations, where the bulk electronic structure as well as surface - related features have been investigated using spin - resolved photoelectron spectroscopy ( sr - ups ) and for a larger probing depth spin - integrated high energy x - ray photoemission spectroscopy ( haxpes ).   the results are interpreted in comparison with first - principles band structure and photoemission calculations which consider all relativistic, surface and high - energy effects properly.
mixture modelling involves explaining some observed evidence using a combination of probability distributions.   the crux of the problem is the inference of an optimal number of mixture components and their corresponding parameters.   this paper discusses unsupervised learning of mixture models using the bayesian minimum message length ( mml ) criterion. to demonstrate the effectiveness of search and inference of mixture parameters using the proposed approach, we select two key probability distributions, each handling fundamentally different types of data : the multivariate gaussian distribution to address mixture modelling of data distributed in euclidean space, and the multivariate von mises - fisher ( vmf ) distribution to address mixture modelling of directional data distributed on a unit hypersphere. the key contributions of this paper, in addition to the general search and inference methodology, include the derivation of mml expressions for encoding the data using multivariate gaussian and von mises - fisher distributions, and the analytical derivation of the mml estimates of the parameters of the two distributions.   our approach is tested on simulated and real world data sets.   for instance, we infer vmf mixtures that concisely explain experimentally determined three - dimensional protein conformations, providing an effective _ null model   _ description of protein structures that is central to many inference problems in structural bioinformatics.   the experimental results demonstrate that the performance of our proposed search and inference method along with the encoding schemes improve on the state of the art mixture modelling techniques.
deryagin, grigoriev, and rubakov ( dgr ) have shown that in finite - density qcd at infinite @xmath0 the fermi surface is unstable with respect to the formation of chiral waves with wavenumber twice the fermi momentum, while the bcs instability is suppressed.   we show here that at large, but finite @xmath0, the dgr instability only occurs in a finite window of chemical potentials from above @xmath1 to @xmath2, where @xmath3.   our analysis shows that, at least in the perturbative regime, the instability occurs only at extremely large @xmath0, @xmath4, where @xmath5 is the number of flavors.   we conclude that the dgr instability is not likely to occur in qcd with three colors, where the ground state at finite density is expected to be a color superconductor.   we speculate on the possible structure of the ground state of finite - density qcd with very large @xmath0.   = 10000 = 10000 = 10000 = 5000 = 10000 = 100 = 100    *p *    prepictex pictex postpictex = = # 1 # 2 * # 3 / at # 1 # 2 * # 3 0 -10 /
the diatomic linear chain of masses coupled by harmonic springs is a textboook model for vibrational normal modes ( phonons ) in crystals.   in addition to propagating acoustic and optic branches, this model is known to support a `` gap mode '' localized at the surface, provided the atom at the surface has light rather than heavy mass.   an elementary argument is given which explains this mode and provides values for the frequency and localization length. by reinterpreting this mode in different ways,   we obtain the frequency and localization lengths for three other interesting modes : ( 1 ) the surface vibrational mode of a light mass impurity at the surface of a monatomic chain ; ( 2 ) the localized vibrational mode of a stacking fault in a diatomic chain ; and ( 3 ) the localized vibrational mode of a light mass impurity in a monatomic chain.
we consider tri - bimaximal lepton mixing within low - scale seesaw schemes where light neutrino masses arise from tev scale physics, potentially accessible at the large hadron collider ( lhc ).   two examples are considered, based on the @xmath0 flavor symmetry realized within the inverse or the linear seesaw mechanisms.   both are highly predictive so that in both the light neutrino sector effectively depends only on three mass parameters and one majorana phase, with no cp violation in neutrino oscillations.   we find that the linear seesaw leads to a lower bound for neutrinoless double beta decay while the inverse seesaw does not.   the models also lead to potentially sizeable decay rates for lepton flavor violating processes, tightly related by the assumed flavor symmetry.
imaging and spectroscopy with the very large telescope have revealed 20 ly@xmath0  emitters within a projected distance of 1.3 mpc and 600 km s@xmath1 of the luminous radio galaxy tn j13381942 at @xmath2.   compared to the field density of ly@xmath0  emitters, this implies an overdensity on the order of 15.   the structure has a projected size of at least 2.7 mpc @xmath3 1.8 mpc and a velocity dispersion of 325 km s@xmath1, which makes it the most distant structure known. using the galaxy overdensity and assuming a bias parameter @xmath4 = 3  5, the mass is estimated to be @xmath5 @xmath6.   the radio galaxy itself is surrounded by an uniquely asymmetric ly@xmath0  halo. taken together with our previous data on pks 1138262 at @xmath7, these results suggest that luminous radio sources are excellent tracers of high density regions in the early universe, which evolve into present - day clusters.   the statistics of bright radio sources and of concentrations in the lyman break galaxy population are consistent with the picture that each of those concentrations harbours an active or passive luminous radio source.
we present spectra of 59 nearby stars candidates, m dwarfs and white dwarfs, previously identified using high proper motion catalogues and the denis database.   we review the existing spectral classification schemes and spectroscopic parallax calibrations in the near - infrared @xmath0-band and derive spectral types and distances of the nearby candidates.   42 stars have spectroscopic distances smaller than 25  pc, three of them being white dwarfs.   two targets lie within 10  pc, one m8 star at 10.0  pc ( apmpm j0103 - 3738 ), and one m4 star at 8.3  pc ( lp 225 - 57 ).   one star, lhs 73, is found to be among the few subdwarfs lying within 20 pc.   furthermore, together with lhs 72, it probably belongs to the closest pair of subdwarfs we know.       galaxy : solar neighbourhood  stars : late type  white dwarfs  subdwarfs
the sandpile group @xmath0 of a finite graph @xmath1 is a discrete analogue of the jacobian of a riemann surface which was rediscovered several times in the contexts of arithmetic geometry, self - organized criticality, random walks, and algorithms. given a ribbon graph @xmath1, holroyd _ et al.   _ used the `` rotor - routing '' model to define a free and transitive action of @xmath0 on the set of spanning trees of @xmath1.   however, their construction depends _ a priori _ on a choice of basepoint vertex. ellenberg asked whether this action does in fact depend on the choice of basepoint.   we answer this question by proving that the action of @xmath0 is independent of the basepoint if and only if @xmath1 is a planar ribbon graph.
in this review given at the hot and cool : bridging gaps in massive star evolution conference, i present the state of the art in red supergiant star atmosphere modelling.   the last generation of hydrostatic 1d lte marcs models publicly released in 2008 have allowed great achievements in the past years, like the calibration of effective temperature scales.   i rapidly describe this release, and then i discuss in some length the impact of the opacity sampling approximation on the thermal structure of models and on their emergent spectra.   i also insist on limitations inherent to these models.   estimates of collisional and radiative time scales for electronic transitions in e.g. tio suggest that non - lte effects are important, and should be further investigated.   classical 1d models are not capable either to provide the large and non - gaussian velocity fields we know exist in red supergiants atmospheres.   i therefore also present current efforts in 3d radiative hydrodynamical simulation of rsgs.   i show that line profiles and shifts are predicted by these simulations, without the need for fudge micro- and macroturbulence velocities.   this is a great progress, although line depths and widths are slightly too shallow.   this is probably caused by the simplified grey radiative transfer used in these heavy simulations.   future non - grey 3d simulations should provide a better fit to observations in terms of line strengths and widths.
a modification of the internal structure of jets is expected due to the production of a dense qcd medium, the quark gluon plasma, in heavy - ion collisions.   we discuss some aspects of jet reconstruction in @xmath0 and @xmath1 collisions and emphasize the dramatically increased contribution of the underlying event in nucleus - nucleus collisions as compared with the vacuum case.   we conclude with its consequences on the full jet spectrum and fragmentation function extraction at lhc.
we propose a lattice gas model to account for linear chain structures adsorbed on ( 112 ) faces of tungsten and molybdenum.   this model includes a dipole - dipole interaction as well as a long - range indirect ( oscillatory ) interaction of the form @xmath0, where @xmath1 is the wavevector of electrons at the corresponding fermi surface and @xmath2 is a phase shift.   it is assumed that the structures are stabilized by an attractive indirect interaction along the chains.   we have explicitly demonstrated that the periodic ground states strongly depend on a competition between the dipole - dipole and long - range indirect interactions.   the effect of temperature in our model of linear chain structures is studied within the molecular - field approximation.   the numerical results clearly show that for the dipole - dipole interaction only, all long - periodic linear chain phases are suppressed to low temperatures while phases with periods 2, 3, and 4 dominate the phase diagram.   however, when the long - range indirect interaction becomes important, the long - periodic linear chain phases start to fill up the phase diagram and develop a high thermal stability.   we have chosen model parameters in order to reconstruct a sequence of long - periodic phases ( for coverages less than 0.5 ) as observed experimentally at @xmath3 for li / mo(112 ) and li / w(112 ).   it would be interesting to verify our model and assumptions by checking experimentally the corresponding phase diagrams.    2
we analyze the energy extraction by the penrose process in higher dimensions.   our result shows the efficiency of the process from higher dimensional black holes and black rings can be rather high compared with than that in four dimensional kerr black hole. in particular,   if one rotation parameter vanishes, the maximum efficiency becomes infinitely large because the angular momentum is not bounded from above.   we also apply a catastrophe theory to analyze the stability of black rings.   it indicates a branch of black rings with higher rotational energy is unstable, which should be a different type of instability from the gregory - laflamme s one.
the problem of the dynamo effect for a kraichnan incompressible helicity - free velocity field is considered. exploiting a quantum formalism first introduced by kazantsev ( a.p.   kazantsev, sov.   phys.   jetp * 26 *, 1031 - 1034 ( 1968 ) ), we show that a critical magnetic reynolds number exists for the presence of dynamo.   the value of the prandtl number influences the spatial distribution of the magnetic field and its growth in time.   the magnetic field correlation length is always the largest between the diffusive scale and the viscous scale of the flow. in the same way the field growth is characterized by a time scale that corresponds to the largest between the diffusive and the viscous characteristic time.   +   + * keywords * : turbulent transport, magnetohydrodynamics, dynamo effect, kraichnan statistical ensemble    suggested running head : the kraichnan - kazantsev dynamo +    11em 1em -0.1em 0.5pt plus 0.25pt minus 0.25pt    dario vincenzi + cnrs umr 6529 + bd. de lobservatoire + bp 4229 + 06304 nice cedex 4 - france    + 33 - 4 - 92003172    + 33 - 4 - 92003121    vincenzi@obs-nice.fr
we show that the recently observed elemental abundance pattern of the carbon - rich metal - poor damped lyman @xmath0 ( dla ) system is in excellent agreement with the nucleosynthesis yields of faint core - collapse supernovae of primordial stars.   the observed abundance pattern is not consistent with the nucleosynthesis yields of pair - instability supernovae.   the dla abundance pattern is very similar to that of carbon - rich extremely metal - poor ( emp ) stars, and the contributions from low - mass stars and/or binary effects should be very small in dlas.   this suggests that chemical enrichment by the first stars in the first galaxies is driven by core - collapse supernovae from @xmath1 stars, and also supports the supernova scenario as the enrichment source of emp stars in the milky way galaxy.
we report on the observation of magnetic quantum ratchet effect in ( cd, mn)te- and cdte - based quantum well structures with an asymmetric lateral dual grating gate superlattice subjected to an external magnetic field applied normal to the quantum well plane.   a @xmath0 electric current excited by _ cw _ terahertz laser radiation shows @xmath1-oscillations with an amplitude much larger as compared to the photocurrent at zero magnetic field.   we show that the photocurrent is caused by the combined action of a spatially periodic in - plane potential and the spatially modulated radiation due to the near field effects of light diffraction.   magnitude and direction of the photocurrent are determined by the degree of the lateral asymmetry controlled by the variation of voltages applied to the individual gates.   the observed magneto - oscillations with enhanced photocurrent amplitude result from landau quantization and, for ( cd, mn)te at low temperatures, from the exchange enhanced zeeman splitting in diluted magnetic heterostructures. theoretical analysis, considering the magnetic quantum ratchet effect in the framework of semiclassical approach, describes quite well the experimental results.
recently, it has been presented some algorithms and physical models which give prospects for construction of quantum computers capable to solve systems of linear equations.   the common feature which is shared in these works is the use of qubits which allow to solve systems with @xmath0 variables. in this work   we propose a  quantum circuit based on qutrits architecture which directly allows for solving systems of equations with three variables.   proposed circuit can be easily generalized to those with @xmath1 variables.   we also present some numerical experiments to verify the correctness of proposed solution.
the spectrum of nucleon excitations is dominated by broad and overlapping resonances.   polarization observables in photoproduction reactions are key in the study of these excitations.   they give indispensable constraints to partial - wave analyses and help clarify the spectrum.   a series of polarized photoproduction experiments have been performed at the thomas jefferson national accelerator facility with the cebaf large acceptance spectrometer ( clas ).   these measurements include data with linearly and circularly polarized tagged - photon beams, longitudinally and transversely polarized proton and deuterium targets, and recoil polarizations through the observation of the weak decay of hyperons.   an overview of these studies and recent results will be given.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
the nature of the icy material accreted by comets during their formation in the outer regions of the protosolar nebula is a major open question in planetary science.   some scenarios of comet formation predict that these bodies agglomerated from crystalline ices condensed in the protosolar nebula. concurrently, alternative scenarios suggest that comets accreted amorphous ice originating from the interstellar cloud or from the very distant regions of the protosolar nebula. on the basis of existing laboratory and modeling data,   we find that the n@xmath0/co and ar / co ratios measured in the coma of the jupiter family comet 67p / churyumov - gerasimenko by the rosina instrument aboard the european space agency s rosetta spacecraft match those predicted for gases trapped in clathrates.   if these measurements are representative of the bulk n@xmath0/co and ar / co ratios in 67p / churyumov - gerasimenko, it implies that the ices accreted by the comet formed in the nebula and do not originate from the interstellar medium, supporting the idea that the building blocks of outer solar system bodies have been formed from clathrates and possibly from pure crystalline ices.   moreover, because 67p / churyumov - gerasimenko is impoverished in ar and n@xmath0, the volatile enrichments observed in jupiter s atmosphere can not be explained solely via the accretion of building blocks with similar compositions and require an additional delivery source.   a potential source may be the accretion of gas from the nebula that has been progressively enriched in heavy elements due to photoevaporation.
what should be the quasinormal modes associated with a spacetime that contains a naked singularity instead of a black hole? in the present work we address this problem by studying the scattering of scalar fields on a curved background described by a reissner - nordstrm spacetime with @xmath0.   we show that there is a qualitative difference between cases with @xmath1 and cases with @xmath2.   we discuss the necessary conditions for the well - posedness of the problem, and present results for the low damped modes in the low @xmath3 and large @xmath3 limit.   we also consider the asymptotically highly damped quasinormal modes.   we present strong evidence that such modes are absent in the case of a naked reissner - nordstrm singularity, corroborating recent conjectures relating them to classical and quantum properties of horizons.
with more and more extrasolar planets discovered in and around binary star systems, questions concerning the determination of the classical habitable zone arise.   do the radiative and gravitational perturbations of the second star influence the extent of the habitable zone significantly, or is it sufficient to consider the host - star only? in this article we investigate the implications of stellar companions with different spectral types on the insolation a terrestrial planet receives orbiting a sun - like primary.   we present time independent analytical estimates and compare these to insolation statistics gained via high precision numerical orbit calculations.   results suggest a strong dependence of permanent habitability on the binary s eccentricity, as well as a possible extension of habitable zones towards the secondary in close binary systems.
we design 3d metallic nanowire media with different structures and numerically demonstrate they can be homogeneous effective indefinite anisotropic media by showing their dispersion relations are hyperbolic. for a finite slab, a nice fitting procedure is exploited to obtain the dispersion relations, from which we retrieve the effective permittivities.   the pseudo focusing for the real 3d wire medium agrees very well with the homogeneous medium having the effective permittivity tensor of the wire medium.   studies also show that in the long wavelength limit, the hyperbolic dispersion relation of the 3d wire medium can be valid even for evanescent modes.
high spin states in @xmath0 in were investigated using @xmath1mo(@xmath2o, p3n ) reaction at 80 mev. the excited level   have been observed up to 5.6 mev excitation energy and spin @xmath3 20@xmath4 with the level scheme showing three dipole bands. the polarization and lifetime measurements   were carried out for the dipole bands. tilted axis cranking model calculations were performed for different quasi - particle configurations of this doubly odd nucleus.   comparison of the calculations of the model with the b(m1 ) transition strengths of the positive and negative parity bands firmly established their configurations.
techniques to extract information from spectra of unresolved multi - component systems are revised, with emphasis on recent developments and practical aspects.   we review the cross - correlation techniques developed to deal with such spectra, discuss the determination of the broadening function and compare techniques to reconstruct component spectra.   the recent results obtained by separating or disentangling the component spectra is summarised.   an evaluation is made of possible indeterminacies and random and systematic errors in the component spectra.
we present a study for the pion decay constant @xmath0 in the quenched approximation to lattice qcd with the kogut - susskind ( ks ) quark action, with the emphasis given to the renormalization problems.   numerical simulations are carried out at the couplings @xmath1 and 6.2 on @xmath2 and @xmath3 lattices, respectively.   the pion decay constant is evaluated for all ks flavors via gauge invariant and non - invariant axial vector currents with the renormalization constants calculated by both non - perturbative method and perturbation theory.   we obtain @xmath4 mev in the continuum limit as the best value using the partially conserved axial vector current, which requires no renormalization. from a study for the other ks flavors we find that the results obtained with the non - perturbative renormalization constants are well convergent among the ks flavors in the continuum limit, confirming restoration of @xmath5 flavor symmetry, while perturbative renormalization still leaves an apparent flavor breaking effect even in the continuum limit.
the origin of equilibrium gravitational configurations is sought in terms of the stability of their trajectories, as described by the curvature of their lagrangian configuration manifold of particle positions  a context in which subtle spurious effects originating from the singularity in the two body potential become particularly clear.   we focus on the case of spherical systems, which support only regular orbits in the collisionless limit, despite the persistence of local exponential instability of @xmath0-body trajectories in the anomalous case of discrete point particle representation even as @xmath1.   when the singularity in the potential is removed, this apparent contradiction disappears. in the absence of fluctuations  , equilibrium configurations generally correspond to positive scalar curvature, and thus support stable trajectories.   a null scalar curvature is associated with an effective, averaged, equation of state describing dynamically relaxed equilibria with marginally stable trajectories.   the associated configurations are quite similar to those of observed elliptical galaxies and simulated cosmological halos, and are necessarily different from the systems dominated by isothermal cores, expected from entropy maximization in the context of the standard theory of violent relaxation.   it is suggested that this is the case because a system starting far from equilibrium does not reach a most probable state via violent relaxation, but that this process comes to an end as the system finds and ( settles in ) a configuration where it can most efficiently wash out perturbations.   we explicitly test this interpretation by means of direct simulations.
during the last three decades, evidence has mounted that star and planet formation is not an isolated process, but is influenced by current and previous generations of stars.   although cool stars form in a range of environments, from isolated globules to rich embedded clusters, the influences of other stars on cool star and planet formation may be most significant in embedded clusters, where hundreds to thousands of cool stars form in close proximity to ob stars. at the cool stars 14 meeting, a splinter session was convened to discuss the role of environment in the formation of cool stars and planetary systems ; with an emphasis on the `` hot '' environment found in rich clusters.   we review here the basic results, ideas and questions presented at the session.   we have organized this contribution into five basic questions : what is the typical environment of cool star formation, what role do hot star play in cool star formation, what role does environment play in planet formation, what is the role of hot star winds and supernovae, and what was the formation environment of the sun? the intention is to review progress made in addressing each question, and to underscore areas of agreement and contention.
the cross over from low to high carrier densities in a many - polaron system is studied in the framework of the one - dimensional spinless holstein model, using unbiased numerical methods. combining a novel quantum monte carlo approach and exact diagonalization,   accurate results for the single - particle spectrum and the electronic kinetic energy on fairly large systems are obtained.   a detailed investigation of the quality of the monte carlo data is presented. in the physically most important adiabatic intermediate electron - phonon coupling regime, for which no analytical results are available, we observe a dissociation of polarons with increasing band filling, leading to normal metallic behavior, while for parameters favoring small polarons, no such density - driven changes occur.   the present work points towards the inadequacy of single - polaron theories for a number of polaronic materials such as the manganites.
multiwavelength identification of agn is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity ( obscuration, efficiency, etc. ).   a panchromatic strategy plays an especially important role when the host galaxies are star - forming. selecting far - infrared galaxies at @xmath0, and using agn tracers in the x - ray, optical spectra, mid - infrared, and radio regimes, we found a twice higher agn fraction than previous studies, thanks to the combined agn identification methods and in particular the recent mass - excitation ( mex ) diagnostic diagram.   we furthermore find an intriguing relation between agn x - ray absorption and the specific star formation rate ( ssfr ) of the host galaxies, indicating a physical link between x - ray absorption and either the gas fraction or the gas geometry in the hosts.   these findings have implications for our current understanding of both the agn unification model and the nature of the black hole - galaxy connection.
we demonstrate that a phase - independent quantum amplifier of a polarization qubit is a complementary amplifier of the heralded qubit amplifier .   it employs the multi - functional cloner in @xmath0 copying regime, capable of providing approximate copies of qubits given by various probability distributions, and is optimized for distributions with axial symmetry.   direct applications of the proposed solution are possible in quantum technologies, doubling the range where quantum information is coherently broadcast.   it also outperforms natural nonlinear amplifiers that use stimulated emission in bulk nonlinear materials.   we consider the amplifier to be an important tool for amplifying quantum information sent via quantum channels with phase - independent damping.
two - dimensional hydrodynamical simulations were made to calibrate the mixing length parameter for modeling red giant s convective envelope. as was briefly reported in @xcite, a comparison of simulations starting with models   integrated with different values of the mixing length parameter, has been made. in this paper   more results are presented, including tests of the spatial resolution and large eddy simulation terms used by the numerical code.   the consistent value of the mixing length parameter was found to be 1.4, for a red giant of mass @xmath0, core mass of @xmath1, luminosity of @xmath2, and metallicity @xmath3.
we calculate the universal spectrum of trimer and tetramer states in heteronuclear mixtures of ultracold atoms with different masses in the vicinity of the heavy - light dimer threshold. to extract the energies, we solve the three- and four - body problem for simple two- and three - body potentials tuned to the universal region using the gaussian expansion method.   we focus on the case of one light particle of mass @xmath0 and two or three heavy bosons of mass @xmath1 with resonant heavy - light interactions.   we find that trimer and tetramer cross into the heavy - light dimer threshold at almost the same point and that as the mass ratio @xmath2 decreases, the distance between the thresholds for trimer and tetramer states becomes smaller.   we also comment on the possibility of observing exotic three - body states consisting of a dimer and two atoms in this region and compare with previous work.
minkowski space is the simplest four - dimensional lorentzian manifold, being topologically trivial and globally flat, and hence the simplest model of spacetime  from a general - relativistic point of view.   but this does not mean that it is altogether structurally trivial.   in fact, it has a very rich structure, parts of which will be spelled out in detail in this contribution, which is written for _ minkowski spacetime : a hundred years later _, edited by vesselin petkov, to appear in 2008 in the springer series on fundamental theories of physics, springer verlag, berlin.
once thought to be devoid of warm and cold interstellar matter, elliptical galaxies are now commonly observed to host extended regions of neutral and ionized gas.   outside of the innermost nuclear regions of these galaxies, the favoured candidate ionizing source remains some component of the stellar population, with mounting evidence suggesting post - asymptotic - giant - branch stars ( pagbs ). in a recent paper  , we demonstrated that observations of recombination lines of he ii ( or upper limits thereof ) may provide a strong constraint on the presence of any other, higher temperature ionizing sources, in particular nuclear - burning white dwarfs in the context of the single degenerate ( sd ) scenario for type ia supernovae.   the sensitivity of the heii test is greatest for wd effective temperatures @xmath0 @xmath1. here   we extend our analysis to include predictions for all of the `` classical '' strong optical lines, as well as uv, optical, and infra - red lines of neutral oxygen, nitrogen, and singly - ionized carbon.   this allows us to extend the temperature range over which we can meaningfully constrain the collective luminosity of nuclear - burning wds to @xmath2 @xmath3 t @xmath3 @xmath4.   we then demonstrate how observations of nearby early - type and post - starburst galaxies can place strong limits on the origin of type ia supernovae.       binaries : close  supernovae : ia  nebulae : emission - line galaxies
we study scalar field theories on poincar invariant commutative nonassociative spacetimes.   we compute the one - loop self - energy diagrams in the ordinary path integral quantization scheme with feynman s prescription, and find that the cutkosky rule is satisfied.   this property is in contrast with that of noncommutative field theory, since it is known that noncommutative field theory with space / time noncommutativity violates unitarity in the above standard scheme, and the quantization procedure will necessarily become complicated to obtain a sensible poincar invariant noncommutative field theory.   we point out a peculiar feature of the non - locality in our nonassociative field theories, which may explain the property of the unitarity distinct from noncommutative field theories.   thus commutative nonassociative field theories seem to contain physically interesting field theories on deformed spacetimes.   yuya sasai and   naoki sasakura     +
the non - stationary evolution of observable quantities in complex systems can frequently be described as a juxtaposition of quasi - stationary spells. given that standard theoretical and data analysis approaches usually rely on the assumption of stationarity, it is important to detect in real time series intervals holding that property.   with that aim, we introduce a segmentation algorithm based on a fully non - parametric approach.   we illustrate its applicability through the analysis of real time series presenting diverse degrees of non - stationarity, thus showing that this segmentation procedure generalizes and allows to uncover features unresolved by previous proposals based on the discrepancy of low order statistical moments only.
astrophysical and cosmological observations do not require the dark matter particles to be absolutely stable.   if they are indeed unstable, their decay into positrons might occur at a sufficiently large rate to allow the indirect detection of dark matter through an anomalous contribution to the cosmic positron flux. in this paper   we discuss the implications of the excess in the positron fraction recently reported by the pamela collaboration for the scenario of decaying dark matter. to this end  , we have performed a model - independent analysis of possible signatures by studying various decay channels in the case of both a fermionic and a scalar dark matter particle.   we find that the steep rise in the positron fraction measured by pamela at energies larger than 10 gev can naturally be accommodated in several realizations of the decaying dark matter scenario.   4.5 mm = -1.5 cm 4.5 mm cite#1#2@tempswa tempcntc citex#2@fileswauxout tempcnta@tempcntb@neciteaciteforciteb:=#2citeo#1 citeotempcnta > tempcntbciteacitea, tempcnta = tempcntbtempcnta    # 1 # 1    # 1 # 1   @=11 stequation   @=12    -17.0 cm
we develop a continuum theory for equilibrium elasticity of a network of crosslinked semiflexible filaments, spanning the full range between flexible entropy - driven chains to stiff athermal rods.   we choose the 3-chain constitutive model of network elasticity over several plausible candidates, and derive analytical expressions for the elastic energy at arbitrary strain, with the corresponding stress - strain relationship.   the theory fits well to a wide range of experimental data on simple shear in different filament networks, quantitatively matching the differential shear modulus variation with stress, with only two adjustable parameters ( which represent the filament stiffness and the pre - tension in the network, respectively ).   the general theory accurately describes the crossover between the positive and negative poynting effect ( normal stress on imposed shear ) on increasing the stiffness of filaments forming the network.   we discuss the network stability ( the point of marginal rigidity ) and the phenomenon of tensegrity, showing that filament pre - tension on crosslinking into the network determines the magnitude of linear modulus @xmath0.   + _ soft matter _ : received 03 may 2016, accepted 08 jul 2016 ; doi : 10.1039/c6sm01029f
the degree of beaming in gamma - ray bursts ( grbs ) is currently unknown.   the uncertainty in the @xmath0-ray beaming angle, @xmath1, leaves the total energy release ( @xmath2 ) and the event rate per galaxy ( @xmath3 ) unknown to within orders of magnitude.   since the delayed radio emission of grb sources originates from a mildly relativistic shock and receives only weak relativistic beaming, the rate of radio - selected transients with no grb counterparts can be used to set an upper limit on @xmath4.   we find that a vla survey with a sensitivity of @xmath5 mjy at 10 ghz could identify @xmath6 radio afterglows across the sky if each source is sampled at least twice over a period of one month or longer. from the total number of @xmath7 0.1 mjy sources observed at 8.44 ghz and the fraction of fading sources at 1.44 ghz  , we get the crude limit @xmath8.
lead sulfide is an important semiconductor that has found technological applications for over a century.   raman spectroscopy, a standard tool for the investigation and characterization of semiconductors, has limited application to this material because of the forbidden nature of its first order scattering and its opacity to visible lasers.   nevertheless, useful vibrational spectra from two - phonon processes are obtained with red lasers, probably because of a resonance in the concomitant electronic transitions. here   we report temperature dependent spectra, covering the 10 - 300k range, for two samples with different sulfur isotopic compositions.   the results are analyzed by comparison with _ ab initio _ calculations of the lattice dynamics of pbs and the corresponding densities of one and two - phonon states.   emphasis is placed on the analysis of the two phonon band centered at @xmath0.
we report the discovery of a 1620@xmath0 radial velocity companion around the very young ( @xmath13myr ) brown dwarf candidate chah@xmath28 ( m5.75m6.5 ). based on high - resolution echelle spectra of chah@xmath28 taken between 2000 and 2007 with uves at the vlt  , a companion was detected through rv variability with a semi - amplitude of 1.6kms@xmath3.   a kepler fit to the data yields an orbital period of the companion of 1590  days and an eccentricity of @xmath4=0.49.   a companion minimum mass @xmath5 between 16 and 20@xmath0 is derived when using model - dependent mass estimates for the primary.   the mass ratio @xmath6 might be as small as 0.2 and, with a probability of 87%, it is less than 0.4.   chah@xmath28 harbors most certainly the lowest mass companion detected so far in a close ( @xmath1 1au ) orbit around a brown dwarf or very low - mass star. from the uncertainty in the orbit solution, it can not completely be ruled out that the companion has a mass in the planetary regime.   its discovery is in any case an important step towards rv planet detections around bds.   further, chah@xmath28 is the fourth known spectroscopic brown dwarf or very low - mass binary system with an rv orbit solution and the second known very young one.
email graphs have been used to illustrate general properties of social networks of communication and collaboration. however, increasingly, the majority of email traffic reflects opportunistic, rather than symbiotic social relations.   here we use e - mail data drawn from a large university to construct directed graphs of email exchange that quantify the differences between social and antisocial behaviors in networks of communication.   we show that while structural characteristics typical of other social networks are shared to a large extent by the legitimate component they are not characteristic of antisocial traffic.   interestingly, opportunistic patterns of behavior do create nontrivial graphs with certain general characteristics that we identify. to complement the graph analysis, which suffers from incomplete knowledge of users external to the domain  , we study temporal patterns of communication to show that the dynamical properties of email traffic can, in principle, distinguish different types of social relations.
hamiltonian systems, when coupled _ via _ time  delayed interactions, do not remain conservative. in the uncoupled system,   the motion can typically be periodic, quasiperiodic or chaotic.   this changes drastically when delay coupling is introduced since now attractors can be created in the phase space. in particular for sufficiently strong coupling there can be amplitude death ( ad ), namely the stabilization of point attractors and the cessation of oscillatory motion.   the approach to the state of ad or oscillation death is also accompanied by a phase  flip in the transient dynamics.   a discussion and analysis of the phenomenology is made through an application to the specific cases of harmonic as well as anharmonic coupled oscillators, in particular the hnon - heiles system.
the exclusive diffractive production of vector mesons and real photons in @xmath0 collisions has been studied at hera in a wide kinematic range. here   the most recent experimental results are presented together with a regge - type model and projects for new diffractive studies at lhc.
blazars are characterized by large amplitude and fast variability, indicating that the electron distribution is rapidly changing, often on time scales shorter than the light crossing time.   the emitting region is sufficiently compact to let radiative losses dominate the cooling of high energy electrons.   we study the time dependent behaviour of the electron distribution after episodic electron injection phases, and calculate the observed synchrotron and self compton radiation spectra.   since photons produced in different part of the source have different travel times, the observed spectrum is produced by the electron distribution at different stages of evolution.   even a homogeneous source then resembles an inhomogeneous one.   time delays between the light curves of fluxes at different frequencies are possible, as illustrated for the specific case of the bl lac object mkn 421.    psfig.tex    galaxies : active  bl lacertae objects : individual : mkn 421  radiation mechanisms : nonthermal  methods : numerical  x  rays : galaxies
we present a method to simulate the polarization properties of extragalactic radio sources at microwave frequencies.   polarization measurements of nearly @xmath0 sources at 1.4ghz are provided by the nvss survey. using this catalogue and the gb6 survey, we study the distribution of the polarization degree of both steep and flat  spectrum sources.   we find that the polarization degree is anti  correlated with the flux density for the former population, while no correlation is detected for the latter.   the available high  frequency data are exploited to determine the frequency dependence of the distribution of polarization degrees.   using such information and the evolutionary model by @xcite, we estimate the polarization power spectrum of extragalactic radio sources at @xmath1ghz and their contamination of cmb polarization maps.   two distinct methods to compute point   source polarization spectra are presented, extending and improving the one generally used in previous analyses.   while extragalactic radio sources can significantly contaminate the cmb e - mode power spectrum only at low frequencies ( @xmath2ghz ), they can severely constrain the detectability of the cmb b  mode up to @xmath3ghz.       radio continuum : galaxies  polarization  cosmic microwave background
from previous studies of the effect of primordial magnetic fields on early structure formation, we know that the presence of primordial magnetic fields during early structure formation could induce more perturbations at small scales ( at present 110 @xmath0mpc ) as compared to the usual @xmath1cdm theory.   matter power spectrum over these scales are effectively probed by cosmological observables such as shear correlation and ly@xmath2 clouds, in this paper we discuss the implications of primordial magnetic fields on the distribution of ly@xmath2 clouds.   we simulate the line of sight density fluctuation including the contribution coming from the primordial magnetic fields.   we compute the evolution of ly@xmath2 opacity for this case and compare our theoretical estimates of ly@xmath2 opacity with the existing data to constrain the parameters of the primordial magnetic fields.   we also discuss the case when the two density fields are correlated.   our analysis yields an upper bounds of roughly @xmath3 on the magnetic field strength for a range of nearly scale invariant models, corresponding to magnetic field power spectrum index @xmath4.
we examine the radiation spectra from relativistic electrons moving in a langmuir turbulence expected to exist in high energy astrophysical objects by using numerical method.   the spectral shape is characterized by the spatial scale @xmath0, field strength @xmath1, and frequency of the langmuir waves, and in term of frequency they are represented by @xmath2, @xmath3, and @xmath4, respectively.   we normalize @xmath5 and @xmath6 by @xmath7 as @xmath8 and @xmath9, and examine the spectral shape in the @xmath10 plane. an earlier study based on diffusive radiation in langmuir turbulence ( drl ) theory by fleishman & toptygin showed that the typical frequency is @xmath11 and that the low frequency spectrum behaves as @xmath12 for @xmath13 irrespective of @xmath14. here  , we adopt the first principle numerical approach to obtain the radiation spectra in more detail.   we generate langmuir turbulence by superposing fourier modes, inject monoenergetic electrons, solve the equation of motion, and calculate the radiation spectra using lienard - wiechert potential.   we find different features from the drl theory for @xmath15.   the peak frequency turns out to be @xmath16 which is higher than @xmath11 predicted in the drl theory, and the spectral index of low frequency region is not @xmath17 but @xmath18. it is because the typical deflection angle of electrons is larger than the angle of the beaming cone @xmath19.   we call the radiation for this case `` wiggler radiation in langmuir turbulence '' ( wrl ).
we formulate a general method for perturbative evaluations of statistics of smoothed cosmic fields, and provide useful formulas in application of the perturbation theory to various statistics.   this formalism is an extensive generalization of the method used by @xcite who derived a weakly nonlinear formula of the genus statistic in a 3d density field. after describing the general method  , we apply the formalism to a series of statistics, including genus statistics, level - crossing statistics, minkowski functionals, and a density extrema statistic, regardless of the dimensions in which each statistic is defined.   the relation between the minkowski functionals and other geometrical statistics is clarified.   these statistics can be applied to several cosmic fields, including 3d density field, 3d velocity field, 2d projected density field, and so forth.   the results are detailed for second order theory of the formalism.   the effect of the bias is discussed.   the statistics of smoothed cosmic fields as functions of rescaled threshold by volume - fraction are discussed in the framework of second - order perturbation theory. in cdm - like models,   their functional deviations from linear predictions plotted against the rescaled threshold are generally much smaller than that plotted against the direct threshold.   there is still slight meat - ball shift against rescaled threshold, which is characterized by asymmetry in depths of troughs in the genus curve.   a theory - motivated asymmetry factor in genus curve is proposed.
we present results from four _ rossi x - ray timing explorer ( rxte ) _ observations of the bright low mass x - ray binary lmc  x2. during   these observations, which span a year and include over 160  hrs of data, the source exhibits clear evolution through three branches on its hardness - intensity and color - color diagrams, consistent with the flaring, normal, and horizontal branches ( fb, nb, hb ) of a @xmath0-source, and remarkably similar to @xmath0-tracks derived for gx  17@xmath12, sco x1 and gx  349@xmath12. lmc  x2 was observed in the fb, nb, and hb for roughly 30%, 40%, and 30% respectively of the total time covered.   the source traces out the full extent of the @xmath0 in @xmath21 day, and the @xmath0-track shows evidence for secular shifts on a timescale in excess of a few days.   although the count rate of lmc  x2 is low compared with the other known @xmath0-sources due to its greater distance, the power density spectra selected by branch show very - low - frequency noise characteristics at least consistent with those from other @xmath0-sources.   we thus confirm the identification of lmc  x2 as a @xmath0-source, the first identified outside our galaxy.
semi - labeled trees are phylogenies whose internal nodes may be labeled by higher - order taxa.   thus, a leaf labeled _ mus musculus _ could nest within a subtree whose root node is labeled rodentia, which itself could nest within a subtree whose root is labeled mammalia.   suppose we are given collection @xmath0 of semi - labeled trees over various subsets of a set of taxa.   the ancestral compatibility problem asks whether there is a semi - labeled tree @xmath1 that respects the clusterings and the ancestor / descendant relationships implied by the trees in @xmath0.   we give a @xmath2 algorithm for the ancestral compatibility problem, where @xmath3 is the total number of nodes and edges in the trees in @xmath0.   unlike the best previous algorithm, the running time of our method does not depend on the degrees of the nodes in the input trees.
we report on a new spectroscopic analysis of the very metal deficient star g6412 ( =@xmath03.3 ), aimed at determining, for the first time, its beryllium content.   the spectra were observed during the science verification of uves, the eso vlt ultraviolet and visible echelle spectrograph. the high resolution ( @xmath148000 ) and high s / n ( @xmath1130 per pixel ) achieved at the wavelengths of the resonance doublet allowed an accurate determination of its abundance : log n(be / h ) = @xmath013.10 @xmath2 0.15  dex.   the be abundance is significantly higher than expected from previous measurements of be in stars of similar metallicity ( 3d and nlte corrections acting to make a slightly higher value than an lte analysis ).   when compared to iron, the high  ratio thus found may suggest a flattening in the beryllium evolutionary trend at the lowest metallicity end or the presence of dispersion at early epochs of galactic evolution.
we explore the effect of substructure in dark matter halos on the power spectrum and bispectrum of matter fluctuations and weak lensing shear. by experimenting with substructure in a cosmological @xmath0 simulation  , we find that when a larger fraction of the host halo mass is in subhalos, the resulting power spectrum has less power at @xmath1 mpc@xmath2 and more power at @xmath3 mpc@xmath2.   we explain this effect using an analytic halo model including subhalos, which shows that the @xmath1 mpc@xmath2 regime depends sensitively on the radial distribution of subhalo centers while the interior structure of subhalos is important at @xmath3 mpc@xmath2.   the corresponding effect due to substructures on the weak lensing power spectrum is up to @xmath4 at angular scale @xmath5.   predicting the nonlinear power spectrum to a few percent accuracy for future surveys would therefore require large cosmological simulations that also have exquisite numerical resolution to model accurately the survivals of dark matter subhalos in the tidal fields of their hosts.
heckman introduced @xmath0 operators on the space of polynomials in @xmath0 variables, such that these operators form a covariant set relative to permutations of the operators and variables, and such that jack symmetric polynomials are eigenfunctions of the power sums of these operators.   we introduce the analogues of these @xmath0 operators for macdonald symmetric polynomials, by using cherednik operators.   the latter operators pairwise commute, and macdonald polynomials are eigenfunctions of their power sums.   we compute the limits of our operators at @xmath1.   these limits yield a lax operator for macdonald symmetric functions.   1200 -35 mm
i report on a sample of new type  i x - ray bursters, firstly detected with the wide field cameras on board _ bepposax _ and then studied with the narrow field instruments on a broad spectral range ( 0.1 - 200 kev ).   properties of the transient / persistent emission are summarized and the broad band x - ray spectra discussed in detail for a few sources.   _ istituto di astrofisica spaziale ( ias / cnr ), via fosso del cavaliere 100,00133 roma, italy _    on behalf of the _ bepposax_/wfc galactic bulge collaboration
the continued - fraction method to solve classical fokker   planck equations has been adapted to tackle quantum master equations of the caldeira  leggett type.   this can be done taking advantage of the phase - space ( wigner ) representation of the quantum density matrix.   the approach differs from those in which some continued - fraction expression is found for a certain quantity, in that the full solution of the master equation is obtained by continued - fraction methods.   this allows to study in detail the effects of the environment ( fluctuations and dissipation ) on several classes of nonlinear quantum systems.   we apply the method to the canonical problem of quantum brownian motion in periodic potentials both for cosine and ratchet potentials ( lacking inversion symmetry ).
we investigate the possibility of doing momentum space lattice simulations as an alternative to the conventional method.   the procedure is introduced and tested for quenched qed2 and quenched qed3.   interesting physical applications to unquenched qed3 and quenched qed4 are also briefly discussed.
this symposium was focused on the hunt for the progenitors of supernovae of type ia.   is there a main channel for the production of sneia?   if so, are these elusive progenitors single degenerate or double degenerate systems?   although most participants seemed to favour the single degenerate channel, there was no general agreement on the type of binary system at play.   an observational puzzle that was highlighted was the apparent paucity of super - soft sources in our galaxy and also in external galaxies.   the single degenerate channel ( and as it was pointed out, quite possibly also the double degenerate channel ) requires the binary system to pass through a phase of steady nuclear burning.   however, the observed number of super - soft sources falls short by a factor of up to 100 in explaining the estimated birth rates of sneia.   thus, are these super - soft sources somehow hidden away and radiating at different wavelengths or are we missing some important pieces of this puzzle that may lead to the elimination of a certain class of progenitor?   another unanswered question concerns the dependence of sneia luminosities on the age of their host galaxy.   several hypotheses were put forward, but none was singled out as the most likely explanation.   it is fair to say that at the end of the symposium the definitive answer to the vexed progenitor question remained is well and truly wide open.
we study a black hole solution for the generalized einstein hilbert action with scale dependent couplings @xmath0 and @xmath1. the form of the couplings is not imposed, but rather deduced from the existence of a non trivial symmetrical solution.   a classical - like choice of the integration constants is found.   finally, the induced flow of the couplings is derived and compared to the flow that is obtained in the context of the exact renormalization group approach.
we carry out a completely first - principles study of the ferroelectric phase transitions in batio@xmath0.   our approach takes advantage of two features of these transitions : the structural changes are small, and only low - energy distortions are important.   based on these observations, we make systematically improvable approximations which enable the parameterization of the complicated energy surface.   the parameters are determined from first - principles total - energy calculations using ultra - soft pseudopotentials and a preconditioned conjugate - gradient scheme.   the resulting effective hamiltonian is then solved by monte carlo simulation. the calculated phase sequence, transition temperatures, latent heats, and spontaneous polarizations are all in good agreement with experiment.   we find the transitions to be intermediate between order - disorder and displacive character.   we find all three phase transitions to be of first order.   the roles of different interactions are discussed.
the equilibrium conditions impose nontrivial geometrical constraints on the configurations that a two - dimensional foam can attain. in the first place,   the three centers of the films that converge to a vertex have to be on a line, i.e. all vertices are _   aligned_. moreover an equilibrated foam must admit a _   reciprocal figure_. this means that it must be possible to find a set of points @xmath0 on the plane, one per bubble, such that the segments @xmath1 are normal to the corresponding foam films.   it is furthermore shown that these constraints are equivalent to the requirement that the foam be a sectional multiplicative partition ( smvp ).   a smvp is a cut with a two - dimensional plane, of a three - dimensional multiplicative partition.   thus given an arbitrary equilibrated foam, we can always find point - like sources ( one per bubble ) in three dimensions that reproduce this foam as a generalized partition.   these sources are the only degrees of freedom that we need in oder to fully describe the foam.
the left - right supersymmetric model contains a right - handed gaugino, as well as several higgsinos, in addition to the minimal supersymmetric model.   thus several cp - noninvariant phases appear in this sector.   we analyze their impact on chargino masses and find that only two combinations are physically relevant.   we then study the production of charginos in @xmath0 annihilation and chargino decays into a sneutrino and a lepton, and investigate the effects of cp - phases.   we also study the cp - odd asymmetry in the production and subsequent decay at the linear collider with longitudinally polarized beams and find a large enhancement when the decay channel to the right sneutrino is available.   the effects of the phases in the left - right supersymmetric chargino sector are different from the minimal supersymmetric standard model, and signals from this sector would be able to distinguish between different gauge symmetries.   -2.5 cm
we report on a coastal experiment to study gps l1 reflections.   the campaign was carried out at the barcelona port breaker and dedicated to the development of sea - state retrieval algorithms.   an experimental system built for this purpose collected and processed gps data to automatically generate a times series of the interferometric complex field ( icf ).   the icf was analyzed off line and compared to a simple developed model that relates icf coherence time to the ratio of significant wave height ( swh ) and mean wave period ( mwp ). the analysis using this model showed good consistency between the icf coherence time and nearby oceanographic buoy data.   based on this result, preliminary conclusions are drawn on the potential of coastal gnss - r for sea state monitoring using semi - empirical modeling to relate gnss - r icf coherence time to swh.
we present a renormalization group study of the scalar potential in a minimal @xmath0 extension of the standard model involving one extra heavier higgs and three heavy right - handed neutrinos with family universal b - l charge assignments.   we implement a type - i seesaw for the masses of the light neutrinos of the standard model.   in particular, compared to a previous study, we perform a two - loop extension of the evolution, showing that two - loop effects are essential for the study of the stability of the scalar potential up to the planck scale.   the analysis includes the contribution of the kinetic mixing between the two abelian gauge groups, which is radiatively generated by the evolution, and the one - loop matching conditions at the electroweak scale. by requiring the stability of the potential up to the planck mass, significant constraints on the masses of the heavy neutrinos, on the gauge couplings and the mixing in the higgs sector are identified.   * constraints on abelian extensions of the standard model + *     + _ @xmath1dipartimento di matematica e fisica `` ennio de giorgi '', + universit del salento and infn - lecce, + via arnesano, 73100 lecce, italy _ +
gate control of phosphorus donor based charge qubits in si is investigated using a tight - binding approach.   excited molecular states of @xmath0 are found to impose limits on the allowed donor separations and operating gate voltages.   the effects of surface ( s ) and barrier ( b ) gates are analyzed in various voltage regimes with respect to the quantum confined states of the whole device.   effects such as interface ionization, saturation of the tunnel coupling, sensitivity to donor and gate placement are also studied.   it is found that realistic gate control is smooth for any donor separation, although at certain donor orientations the s and b gates may get switched in functionality.   this paper outlines and analyzes the various issues that are of importance in practical control of such donor molecular systems.
this simulation study investigates the dependence of the structure of dry nafion@xmath0-like ionomers on the electrostatic interactions between the components of the molecules. in order to speed equilibration,   a procedure was adopted which involved detaching the side chains from the backbone and cutting the backbone into segments, and then reassembling the macromolecule by means of a strong imposed attractive force between the cut ends of the backbone, and between the non - ionic ends of the side chains and the midpoints of the backbone segments.   parameters varied in this study include the dielectric constant, the free volume, side - chain length, and strength of head - group interactions. a series of coarse - grained mesoscale simulations shows the morphlogy to depend sensitively on the ratio of the strength of the dipole - dipole interactions between the side - chain acidic end groups to the strength of the other electrostatic components of the hamiltonian.   examples of the two differing morphologies proposed by gierke and by gebel emerge from our simulations.
a resonant - cavity enhanced detector operating in the mid - infrared at a wavelength around 3.6 @xmath0 m is demonstrated.   the device is based on a narrow - gap lead salt heterostructure epitaxially grown on a baf@xmath1(111 ) substrate. below 140 k  , the photovoltage clearly shows a single narrow cavity resonance, with a @xmath2 ratio of only 2 % at 80 k.
we investigate the use of maximum distance separable ( mds ) codes to cache popular content to reduce the download delay of wireless content delivery.   in particular, we consider a cellular system where devices roam in an out of a cell according to a poisson random process.   popular content is cached in a limited number of the mobile devices using an mds code and can be downloaded from the mobile devices using device - to - device communication.   we derive an analytical expression for the delay incurred in downloading content from the wireless network and show that distributed caching using mds codes can dramatically reduce the download delay with respect to the scenario where content is always downloaded from the base station and to the case of uncoded distributed caching.
discs with a rotation profile depending on radius and height are subject to an axisymmetric linear instability, the vertical shear instability. here we show that non - axisymmetric perturbations, while eventually stabilized, can sustain huge exponential amplifications with growth rate close to the axisymmetric one.   transient growths are therefore to all effects genuine instabilities.   the ensuing angular momentum transport is positive.   these growths occur when the product of the radial times the vertical wavenumbers ( both evolving with time ) is positive for a positive local vertical shear, or negative for a negative local vertical shear.   + we studied, as well, the interaction of these vertical shear induced growths with a convective instability.   the asymptotic behaviour depends on the relative strength of the axisymmetric vertical shear ( @xmath0 ) and convective ( @xmath1 ) growth rates. + for @xmath2 we observed the same type of behaviour described above - large growths occur with asymptotic stabilization. when @xmath3 the system is asymptotically unstable, with a growth rate which can be slightly enhanced with respect to @xmath1.   + the most interesting feature is the sign of the angular momentum transport.   this is always positive in the phase in which the vertical shear driven transients growths occur, even in the case @xmath3.   + thermal diffusion has a stabilizing influence on the convective instability, specially for short wavelengths.   accretion, accretion discs - hydrodynamics - convection - instabilities
this paper concerns the equilibrium bulk charge and current density correlation functions in quantum media, conductors and dielectrics, fully coupled to the radiation ( the retarded regime ).   a sequence of static and time - dependent sum rules, which fix the values of certain moments of the charge and current density correlation functions, is obtained by using rytov s fluctuational electrodynamics.   a technique is developed to extract the classical and purely quantum - mechanical parts of these sum rules.   the sum rules are critically tested in the classical limit and on the jellium model.   a comparison is made with microscopic approaches to systems of particles interacting through coulomb forces only ( the non - retarded regime ).   in contrast with microscopic results, the current - current density correlation function is found to be integrable in space, in both classical and quantum regimes.
in order to test gravitation in the solar system, it is necessary to improve the orbit restitution of interplanetary spacecrafts.   the addition of an accelerometer on board is a major step toward this goal because this instrument measures the non - gravitational acceleration of the spacecraft  . it must be able to perform measurements at low frequencies with no bias to provide an additional observable of interest.   since electrostatic accelerometers suffer a bias, a technological upgrade has been proposed by onera.   it consists in adding to an electrostatic accelerometer a rotating platform which allows modulating the signal of interest and retrieving it without bias after post - processing. using this principle, a measurement method and a post - processing method   have been developed.   the objective of this article is to validate these methods experimentally.   to do so, a horizontally controlled pendulum was used to apply a known signal to an accelerometer mounted on a rotating platform.   the processing of the experimental data demonstrates the ability to make acceleration measurements with no bias.   in addition, the experimental precision on the unbiased acceleration obtained after post - processing corresponds to the precision predicted theoretically.    ] keywords + + + + + + + +    electrostatic accelerometer ; bias rejection ; modulation ; data processing ; precision ; colored noise.   = 1
in the propagation of optical pulses through dispersive media, the frequency degree of freedom acts as an effective decohering environment on the polarization state of the pulse. here   we discuss the application of open - loop dynamical - decoupling techniques for suppressing such a polarization decoherence in one - way communication channels.   we describe in detail the experimental proof of principle of the `` bang - bang '' protection technique recently applied to flying qubits in [ damodarakurup, phys.   rev.   lett. * 103 *, 040502 ].   bang - bang operations are implemented through appropriately oriented waveplates and dynamical decoupling is shown to be potentially useful to contrast a generic decoherence acting on polarization qubits propagating in dispersive media like, e.g., optical fibers.
we investigate the impact of the local spin texture on the differential conductance by scanning tunneling microscopy. in the focus   is the previously found non - collinear magnetoresistance, which originates from spin mixing effects upon electron hopping between adjacent sites with canted magnetic moments. in the present work it is studied with lateral resolution both for the zero magnetic field spin spiral state as well as for individual magnetic skyrmions at different magnetic field values.   we analyze in detail the response of the differential conductance and find different dependencies of peak energy and peak intensity on the local properties of the non - collinear spin texture.   we find that in the center of a skyrmion the peak energy and intensity scale roughly linear with the angle between nearest neighbor moments.   elsewhere in the skyrmion, where the non - collinearity is not isotropic and the magnetization quantization axis varies, the behavior of the peak energy is more complex.
the electron transfer in different solvents is investigated for systems consisting of donor, bridge and acceptor.   it is assumed that vibrational relaxation is much faster than the electron transfer.   electron transfer rates and final populations of the acceptor state are calculated numerically and in an approximate fashion analytically. in wide parameter regimes   these solutions are in very good agreement.   the theory is applied to the electron transfer in @xmath0 with free - base porphyrin ( @xmath1 ) being the donor, zinc porphyrin ( @xmath2 ) the bridge, and quinone ( @xmath3 ) the acceptor.   it is shown that the electron transfer rates can be controlled efficiently by changing the energy of the bridging level which can be done by changing the solvent.   the effect of the solvent is determined for different models.
interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium.   this review discusses the observations and theory of these effects.   metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed.   modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed.   interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion.   cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii.   radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations.   the theory of diffraction and refraction is reviewed, as are the main observations and scintillation regions.
in this work we present a modified tov equation which incorporates the cosmological constant with regard to the recent astronomical observations that the universe is in a phase of accelerated expansion. using this modified tov equation we considered the structure of a neutron star in sds space - time and calculated maximum mass limit for neutron stars.
we perform a theoretical investigation on the thermal conductivity of single - walled boron nitride nanotubes ( swbnt ) using the kinetic theory. by fitting to the phonon spectrum of boron nitride sheet,   we develop an efficient and stable tersoff - derived interatomic potential which is suitable for the study of heat transport in sp2 structures.   we work out the selection rules for the three - phonon process with the help of the helical quantum numbers @xmath0 attributed to the symmetry group ( line group ) of the swbnt.   our calculation shows that the thermal conductivity @xmath1 diverges with length as @xmath2 with exponentially decaying @xmath3, which results from the competition between boundary scattering and three - phonon scattering for flexure modes.   we find that the two flexure modes of the swbnt make dominant contribution to the thermal conductivity, because their zero frequency locates at @xmath4 where @xmath5 is the rotational angle of the screw symmetry in swbnt.
we give efficient algorithms for the fundamental problems of broadcast and local broadcast in dynamic wireless networks.   we propose a general model of communication which captures and includes both fading models ( like sinr ) and graph - based models ( such as quasi unit disc graphs, bounded - independence graphs, and protocol model ).   the only requirement is that the nodes can be embedded in a bounded growth quasi - metric, which is the weakest condition known to ensure distributed operability.   both the nodes and the links of the network are dynamic : nodes can come and go, while the signal strength on links can go up or down.   the results improve some of the known bounds even in the static setting, including an optimal algorithm for local broadcasting in the sinr model, which is additionally uniform ( independent of network size ).   an essential component is a procedure for balancing contention, which has potentially wide applicability.   the results illustrate the importance of carrier sensing, a stock feature of wireless nodes today, which we encapsulate in primitives to better explore its uses and usefulness.
we show how to lift a generic non - scale invariant action in einstein frame into a locally conformally - invariant ( or weyl - invariant ) theory and present a new general form for lagrangians consistent with weyl symmetry.   advantages of such a conformally invariant formulation of particle physics and gravity include the possibility of constructing geodesically complete cosmologies.   we present a conformal - invariant version of the standard model coupled to gravity, and show how weyl symmetry may be used to obtain unprecedented analytic control over its cosmological solutions. within this new framework,   generic frw cosmologies are geodesically complete through a series of big crunch - big bang transitions.   we discuss a new scenario of cosmic evolution driven by the higgs field in a minimal  conformal standard model, in which there is no new physics beyond the standard model at low energies, and the current higgs vacuum is metastable as indicated by the latest lhc data.
the modulation of an optical lattice potential that breaks time - reversal symmetry enables the realization of complex tunneling amplitudes in the corresponding tight - binding model. for a superfluid fermi gas in a triangular lattice potential with complex tunnelings the pairing function acquires a complex phase, so the frustrated magnetism of fermions can be realized.   bose - fermi mixture of bosonic molecules and unbound fermions in the lattice shows also an interesting behavior. due to boson - fermion coupling  , the fermions become slaved by the bosons and the corresponding pairing function takes the complex phase determined by bosons. in the presence of bosons   the fermi system can reveal both gap and gapless superfluidity.
we introduce a minimal agent based model with two classes of agents, fundamentalists ( stabilizing ) and chartists ( destabilizing ) and we focus on the essential features which can generate the stylized facts.   this leads to a detailed understanding of the origin of fat tails and volatility clustering and we propose a mechanism for the self - organization of the market dynamics in the quasi - critical state.   the stylized facts are shown to correspond to finite size effects which, however, can be active at different time scales.   this implies that universality can not be expected in describing these properties in terms of effective critical exponents.   the introduction of a threshold in the agents action ( small price fluctuations lead to no - action ) triggers the self - organization towards the quasi - critical state.   non - stationarity in the number of active agents and in their action plays a fundamental role.   the model can be easily generalized to more realistic variants in a systematic way.
high quality zno thin films were gown using the pulsed laser deposition technique on ( 0001 ) al@xmath0o@xmath1 substrates in an oxidizing atmosphere, using a zn metallic target.   we varied the growth conditions such as the deposition temperature and the oxygen pressure.   first, using a battery of techniques such as x - rays diffraction, rutherford backscattering spectroscopy and atomic force microscopy, we evaluated the structural quality, the stress and the degree of epitaxy of the films.   second, the relations between the deposition conditions and the structural properties, that are directly related to the nature of the thin films, are discussed qualitatively. finally, a number of issues on how to get good - quality zno films are addressed.
we carried out @xmath0co(@xmath1 ) observations toward three star - forming galaxies on the main sequence at @xmath2 with the nobeyama 45 m radio telescope.   these galaxies are detected with _   spitzer_/mips in 24 @xmath3, _   herschel_/spire in 250 @xmath3 and 350 @xmath3, and their gas metallicity, derived from optical emission line ratios based on near infrared spectroscopic observations, is close to the solar metallicity.   although weak signal - like features of co were seen, we could not detect significant co emission.   the dust mass and the upper limits on the molecular gas mass are @xmath4 and @xmath5, respectively.   the upper limits on the gas - to - dust ratios at @xmath2 are @xmath6 which are comparable to the gas - to - dust ratios in local galaxies with similar gas metallicity.   a line stacking analysis enables us to detect a significant co emission and to derive an average molecular gas mass of @xmath7 and gas - to - dust ratio of 250.   this gas - to - dust ratio is also near that in local galaxies with solar metallicity.   these results suggest that the gas - to - dust ratio in star - forming galaxies with solar metallicity does not evolve significantly up to @xmath2. by comparing to a theoretical calculation,   a rapid increase of the dust mass in an earlier epoch of galaxy evolution is suggested.
upcoming weak lensing ( wl ) surveys can be used to constrain dark energy ( de ) properties, namely if tomographic techniques are used to improve their sensitivity. in this work  , we use a fisher matrix technique to compare the power of cmb anisotropy and polarization data with tomographic wl data, in constraining de parameters. adding wl data to available cmb data   improves the detection of all cosmological parameters, but the impact is really strong when de  dm coupling is considered, as wl tomography can then succeed to reduce the errors on some parameters by factors @xmath0
we discuss merging - and - creation as a self - organizing process for scale - free topologies in networks.   three power - law classes characterized by the power - law exponents 3/2, 2 and 5/2 are identified and the process is generalized to networks. in the network context   the merging can be viewed as a consequence of optimization related to more efficient signaling.   scale - free networks, self organized criticality, aggregation, merging    05.40.-a,05.65.+b,89.75.-k,96.60.-j,98.70.vc
we assume some standard choices for the branch cuts of a group of functions and consider the problem of then calculating the branch cuts of expressions involving those functions.   typical examples include the addition formulae for inverse trigonometric functions.   understanding these cuts is essential for working with the single - valued counterparts, the common approach to encoding multi - valued functions in computer algebra systems. while the defining choices are usually simple ( typically portions of either the real or imaginary axes ) the cuts induced by the expression may be surprisingly complicated   we have made explicit and implemented techniques for calculating the cuts in the computer algebra programme maple.   we discuss the issues raised, classifying the different cuts produced.   the techniques have been gathered in the ` branchcuts ` package, along with tools for visualising the cuts. the package is included in maple 17 as part of the ` functionadvisor ` tool.
star clusters are found in @xmath040% of the local group galaxies.   their properties are reviewed.   the impact of galaxy environment on the evolution and survival of star clusters is discussed.   possible evidence for cluster formation triggered by galaxy interactions, gradients in cluster size, metallicity and stellar content with galactocentric radius and variations as a function of galaxy type are briefly summarized.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we have analyzed numerically the response and noise - limited charge sensitivity of a radio - frequency single - electron transistor ( rf - set ) in a non - superconducting state using the orthodox theory.   in particular, we have studied the performance dependence on the quality factor @xmath0 of the tank circuit for @xmath0 both below and above the value corresponding to the impedance matching between the coaxial cable and set.
collective plasma excitations of optically dressed dirac electrons in single and double graphene layers are calculated in the rpa approximation.   the presence of circularly polarized light gives rise to an energy gap @xmath0 between the conduction and valence energy bands.   its value may be adjusted by varying the frequency and intensity of the light, and may reach values of the gap reported for epitaxially grown graphene and far exceeding that caused by spin - orbit coupling.   we report plasmon dispersion relations for various energy gaps and separation between graphene layers. for a single graphene sheet, we find that plasmon modes may be excited for larger wave vector and frequency when subjected to light. for double layers  , we obtained an optical and phonon - like mode and found that the optical mode is not as sensitive as the phonon - like mode in the long wavelength limit when the layer separation is varied, for a chosen @xmath0.   the dressed electron plasma although massive still has dirac origin giving rise to anomalous plasmon behavior upon crossing the @xmath1 cone.
correlations discovered between millisecond timing properties and spectral properties in neutron star x - ray binaries are described and then interpreted in relation to accretion flows in the systems.   use of joint timing and spectral observations to test for the existence of the marginally stable orbit, a key prediction of strong field general relativity, is described and observations of the neutron star x - ray binary 4u  1820 - 303 which suggest that the signature of the marginally stable orbit has been detected are presented.
this brief document provides a description of how to use dice2013r - mc @xcite, a matlab and casadi - based implementation of the dynamic integrated model of climate and economy ( dice ).   dice2013r - mc provides the same basic functionality as the gams code for dice2013r as available at @xcite.
we show that the electron thermal conductivity may strongly affect the heliosheath plasma flow and the global pattern of the solar wind ( sw ) interaction with the local interstellar medium ( lism ).   in particular, it leads to strong reduction of the inner heliosheath thickness that makes possible to explain ( qualitatively ) why voyager  1 ( v1 ) has crossed the heliopause at unexpectedly small heliocentric distance of 122 au. to estimate the effect of thermal conductivity we consider a limiting case when thermal conduction is very effective. to do that we assume the plasma flow in the entire heliosphere is nearly isothermal.    due to this effect  , the heliospheric distance of the termination shock has increased by about 15  au in v1 direction compared to the adiabatic case with @xmath0.   the heliospheric distance of the heliopause has decreased by about 27  au. as a result  , the thickness of the inner heliosheath in the model has decreased by about 42  au and become equal to 32  au.
we show that formally for the standard ansatz relativistic point - coupling mean - field ( rmf - pc ) model a lagrangian density @xmath0 is not equivalent in hartree and hartree - fock approximations.   the equivalency can be achieved only if we use a `` complete '' ansatz at the cost of introducing new parameters in the model.   an approximate treatment of the exchange terms from standard rmf - pc indicates that these effects can not be easily, if at all, absorbed by a dirac - hartree approximation.   # 1#2#3#4#1 * # 2 *, # 3 ( # 4 )    epsf    relativistic hartree - fock, relativistic mean - field model, finite nuclei 21.10.dr, 21.30.fe, 21.60.jz
logistic growth process with nonlocal interactions is considered in one dimension.   spontaneous breakdown of translational invariance is shown to take place at some parameter region, and the bifurcation regime is identified for short and long range interactions.   domain walls between regions of different order parameter are expressed as soliton solutions of the reduced dynamics for nearest neighbor interactions.   the analytic results are confirmed by numerical simulations.
straight - forward models of x - ray reflection in the inner region of accretion discs predict that primary x - ray flux and the flux reflected off the surface of the disc should vary together, albeit a short light travel time delay.   most of the observations, however, show that the x - ray flux can vary while the reflected features remain constant. here   we propose a simple explanation to this. in all likelihood,   the emission of a moderately optically thick magnetic flare atop an accretion disc is anisotropic.   a constant energy release rate in a flare will appear to produce a variable x - ray flux as the flare rotates with the accretion disc anchoring the magnetic tube.   the reflector, on the other hand, receives a constant x - ray flux from the flare.   since the reflected emission is azimuthally symmetric, the observer will see a roughly constant reflected flux ( neglecting relativistic effects ).   the model does not produce quasi - periodic oscillations ( qpo ) if magnetic flux tubes are sheared out faster than they complete one orbit.   galaxy : centre  accretion : accretion discs  galaxies : active
we study the modification of the nucleon nucleon interaction in a nuclear medium in the scalar isoscalar channel, mediated by the exchange of two correlated ( @xmath0 channel ) or uncorrelated pions.   for this purpose we use a standard approach for the renormalization of pions in nuclei.   the corrections obtained for the @xmath1 interaction in the medium in this channel are of the order of 20@xmath2 of the free one in average, and the consideration of short range correlations plays an important role in providing these moderate changes. yet, the corrections are sizable enough to suggest further studies of the stability and properties of nuclear matter.
we report the discovery of a unique object, bd+48 740, a lithium overabundant giant with a(li)=2.33 @xmath0 0.04 ( where a(li)=@xmath1 ), that exhibits radial velocity ( rv ) variations consistent with a 1.6 m@xmath2 companion in a highly eccentric, e=0.67 @xmath0 0.17 and extended, a=1.89  au ( p=771  d ), orbit. the high eccentricity of the planet is uncommon among planetary systems orbiting evolved stars and so is the high lithium abundance in a giant star.   the ingestion by the star of a putative second planet in the system originally in a closer orbit, could possibly allow for a single explanation to these two exceptional facts.   if the planet candidate is confirmed by future rv observations, it might represent the first example of the remnant of a multiple planetary system possibly affected by stellar evolution.
we briefly examine the properties of dense plasmas characteristic of the interior of giant planets and the atmospheres of neutron stars.   special attention is devoted to the equation of state of hydrogen and helium at high density and to the effect of magnetic fields on the properties of dense matter.
registration and management of users in a large scale grid computing environment presents new challenges that are not well addressed by existing protocols. within a single virtual organization ( vo )  , thousands of users will potentially need access to hundreds of computing sites, and the traditional model where users register for local accounts at each site will present significant scaling problems.   however, computing sites must maintain control over access to the site and site policies generally require individual local accounts for every user.   we present here a model that allows users to register once with a vo and yet still provides all of the computing sites the information they require with the required level of trust.   we have developed tools to allow sites to automate the management of local accounts and the mappings between grid identities and local accounts.    * keywords * : grid computing, virtual organization, user accounts, grid user management system.
we find a sufficient condition to imprint the single - mode bosonic phase - space nonclassicality onto a bipartite state as modal entanglement and vice versa using an arbitrary beam splitter.   surprisingly, the entanglement produced or detected in this way depends only on the nonclassicality of the marginal input or output states, regardless of their purity and separability. in this way, our result provides a sufficient condition for generating entangled states of arbitrary high temperature and arbitrary large number of particles.   we also study the evolution of the entanglement within a lossy mach - zehnder interferometer and show that unless both modes are totally lost, the entanglement does not diminish.
we show by direct calculation that the replica and cavity methods are exactly equivalent for the spectrum of erds - rnyi random graph.   we introduce a variational formulation based on the cavity method and use it to find approximate solutions for the density of eigenvalues.   we also use this variational method for calculating spectra of sparse covariance matrices.
we show that the first order ( non co - orbital ) corotation torques are significantly modified by entropy gradients in a non - barotropic protoplanetary disk.   such non - barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap - clearing planets embedded in the disk.   we demonstrate that stellar illumination can heat the gap enough for the planet s orbital eccentricity to instead be excited.   we also discuss the `` eccentricity valley '' noted in the known exoplanet population, where low - metallicity stars have a deficit of eccentric planets between @xmath0 and @xmath1 au compared to metal - rich systems @xcite.   we show that this feature in the planet distribution may be due to the self - shadowing of the disk by a rim located at the dust sublimation radius @xmath0 au, which is known to exist for several t tauri systems. in the shadowed region between @xmath0 and @xmath1   au lack of gap insolation allows disk interactions to damp eccentricity.   outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets.   we suggest that the self - shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.
two - dimensional weyl superconductor is the most elusive member of a group of materials with weyl fermions as low - energy excitations. here, we propose to realize this state in a heterostructure consisting of thin films of half - metal and spin - singlet superconductor. in particular, for the @xmath0-wave case, a very robust two - dimensional weyl superconductor ( dwsc )   is realized independent of the orientation of the spontaneous magnetization of the half - metal.   the quasiparticle spectra of the dwsc show interesting evolution with the direction of the magnetization, featured by a series of lifshitz transitions in the zero - energy contour of the quasiparticle spectrum. for a general magnetization orientation of the half - metal,   the state is a combination of a superconducting component and a normal fluid component and is different from all known forms of pairings.   in addition, we find a transition between type - i and type - ii weyl nodes.   this is also the first example of a type - ii weyl node in the presence of superconducting correlation.   the symmetries and topological properties of the system are analyzed.   we also study the phases in the heterostructure with the half - metal replaced by a ferromagnetic metal with a partially spin - polarized fermi surface.
we report the first results of an observational program designed to determine the luminosity density of high redshift quasars ( z@xmath05 quasars ) using deep multi - colour ccd data.   we report the discovery and spectra of 3 i@xmath121.5 high redshift ( z@xmath04.4 ) quasars, including one with z@xmath05. at z=5.17,   this is the fourth highest redshift quasar currently published. using these preliminary results we derive an estimate of the m@xmath2@xmath1@xmath325.0 ( m@xmath4@xmath1@xmath324.5 ) quasar space density in the redshift range 4.8@xmath1z@xmath15.8 of 3.6@xmath52.5@xmath6@xmath7@xmath8.   when completed the survey will provide a firm constraint on the contribution to the ionizing uv background in the redshift range 4.5@xmath35.5 from quasars by determining the faint end slope of the quasar luminosity function.   the survey uses imaging data taken with the 2.5 m isaac newton telescope as part of the public isaac newton group wide field survey ( wfs ).   this initial sample of objects is taken from two fields of effective area @xmath912.5deg@xmath10 from the final @xmath9100deg@xmath10.    #   1to 0pt#1 # 1 # 1    to size    # 1    to size     # 1 = cmr10 scaled2 = cmbx10 scaled2 = cmti10 scaled2 ps.   = 6truein    galaxies : active,
structure of cold nuclear matter at subnuclear densities for the proton fraction @xmath0, 0.3 and 0.1 is investigated by quantum molecular dynamics ( qmd ) simulations.   we demonstrate that the phases with slablike and rodlike nuclei, etc. can be formed dynamically from hot uniform nuclear matter without any assumptions on nuclear shape, and   also systematically analyze the structure of cold matter using two - point correlation functions and minkowski functionals. in our simulations  , we also observe intermediate phases, which has complicated nuclear shapes.   it is found out that these phases can be characterized as those with negative euler characteristic.   our result implies the existence of these kinds of phases in addition to the simple `` pasta '' phases in neutron star crusts and supernova inner cores.   in addition, we investigate the properties of the effective qmd interaction used in the present work to examine the validity of our results.   the resultant energy per nucleon @xmath1 of the pure neutron matter, the proton chemical @xmath2 in pure neutron matter and the nuclear surface tension @xmath3 are generally reasonable in comparison with other nuclear interactions.
there have been recent reports of charge ordering around @xmath0 in the bilayer manganites. at @xmath0, there appears to be a coexistence region of layered a - type antiferromagnetc and charge order.   there are also reports of orbital order in this region without any jahn - teller effect. based on physical grounds, this region is investigated from a model that incorporates the two orbitals at each mn site and a near - neighbour coulomb repulsion.   it is shown that there indeed is both charge and orbital order close to the half - doped region coincident with a layered magnetic structure. although the orbital order is known to drive the magnetic order, the layered magnetic structure is also favoured in this system by the lack of coherent transport across the planes and the reduced dimensionality of the lattice.   the anisotropic hopping across the orbitals and the underlying layered structure largely determine the orbital arrangements in this region, while the charge order is primarily due to the long range interactions.
observations of normal galactic star - forming regions suggest there is widespread near - uniformity in the initial stellar mass function ( imf ) in spite of diverse physical conditions.   fluctuations may come largely from statistical effects and observational selection.   there are also tantalizing, but uncertain reports that the imf shifts systematically in peculiar regions, giving a low mass bias in quiescent gas, and a high mass bias in active starbursts.   theoretical proposals for the origin of the imf are reviewed.   the theories generally focus on a combination of four physical effects : wind - limited accretion of stellar mass, coalescence of protostellar gas clumps, mass limitations at the thermal jeans mass, and power - law cloud structure.   hybrid theories combining the best of each may be preferred.   # 1#1 0123456789 abcdef    @mtlplain@loaded   = cmssi10 = cmssi10 = cmssi10 = cmmib10 = mtssi10 = mtssbx10 = mtssbi10 = mtmib10 @mtlplain@loaded = cmmib10 at 10pt = cmmib10 at 7pt = cmmib10 at 5pt    = = =    = " 0103    @mtlplain@loaded    @mtlplain@loaded = cmbsy10 = cmbsy10 at 7pt = cmbsy10 at 5pt = = = @ = " 0@72    to be published in `` unsolved problems in stellar evolution, '' ed.   m. livio, cambridge university press, 1999, in press.
we solve the faddeev equation in an exactly poincar invariant formulation of the three - nucleon problem.   the dynamical input is a relativistic nucleon - nucleon ( nn ) interaction that is exactly on - shell equivalent to the high precision cd  bonn nn interaction.   @xmath0-matrix cluster properties dictate how the two - body dynamics is embedded in the three - nucleon mass operator ( rest hamiltonian ).   we find that for neutron laboratory energies above @xmath1  mev relativistic effects on @xmath2 are negligible.   for energies below @xmath1  mev dynamical effects lower the nucleon analyzing power maximum slightly by @xmath3 and wigner rotations lower it further up to @xmath4 increasing thus disagreement between data and theory.   this indicates that three - nucleon forces ( 3nf ) must provide an even larger increase of the @xmath2 maximum than expected up to now.
very often it is an implied paradigm of molecular magnetism that magnetic molecules in a crystal interact so weakly that measurements of dc magnetic observables reflect ensemble properties of single molecules.   but the number of cases where the assumption of virtually non - interacting molecules does not hold grows steadily.   a deviation from the non - interacting case can especially clearly be seen in clusters with antiferromagnetic couplings, where steps of the low - temperature magnetization curve are smeared out with increasing intermolecular interaction. in this investigation   we demonstrate with examples in one-, two, and three space dimensions how intermolecular interactions influence typical magnetic observables such as magnetization, susceptibility and specific heat.
the calice collaboration is developing a granular electromagnetic calorimeter using small scintillator strips for a future linear collider experiment  . on developing of @xmath0 channel - ecal in particle flow approach, calice is developing a technological prototype with 144 of 5@xmath145@xmath1(1 - 2)mm@xmath2 strips on each 180@xmath1180mm@xmath3 base board unit in tandem with developing the design of scintillator strip and pixelated photon detector and their coupling after established the physics prototype which has required performance.   a method of event reconstruction in such ecal is also developed.
motivated by the ideas of using cold alkaline earth atoms trapped in an optical lattice for realization of optical atomic clocks, we investigate theoretically the perturbative effects of atom - atom interactions on a clock transition frequency.   these interactions are mediated by the dipole fields associated with the optically excited atoms.   we predict resonance - like features in the frequency shifts when constructive interference among atomic dipoles occur.   we theoretically demonstrate that by fine - tuning the coherent dipole - dipole couplings in appropriately designed lattice geometries, the undesirable frequency shifts can be greatly suppressed.
we continue our investigation of @xmath0 flavor qcd thermodynamics using dynamical wilson fermions in the fixed scale approach.   two additional pion masses, approximately 440 mev and 285 mev, are added to our previous work at 545 mev.   the simulations were performed at 3 or 4 lattice spacings at each pion mass.   the renormalized chiral condensate, strange quark number susceptibility and polyakov loop is obtained as a function of the temperature and we observe a decrease in the light chiral pseudo - critical temperature as the pion mass is lowered while the pseudo - critical temperature associated with the strange quark number susceptibility or the polyakov loop is only mildly sensitive to the pion mass.   these findings are in agreement with previous continuum results obtained in the staggered formulation.
a general method for obtaining the oscillation periods of the interlayer exchange coupling is presented.   it is shown that it is possible for the coupling to oscillate with additional periods beyond the ones predicted by the rkky theory.   the relation between the oscillation periods and the spacer fermi surface is clarified, showing that non - rkky periods do not bear a direct correspondence with the fermi surface.   the interesting case of a fcc(110 ) structure is investigated, unmistakably proving the existence and relevance of non - rkky oscillations.   the general conditions for the occurrence of non - rkky oscillations are also presented.
stationary, @xmath0-dimensional test branes, interacting with @xmath1-dimensional myers - perry bulk black holes, are investigated in arbitrary brane and bulk dimensions.   the branes are asymptotically flat and axisymmetric around the rotation axis of the black hole with a single angular momentum.   they are also spherically symmetric in all other dimensions allowing a total of @xmath2 group of symmetry.   it is shown that even though this setup is the most natural extension of the spherical symmetric problem to the simplest rotating case in higher dimensions, the obtained solutions are not compatible with the spherical solutions in the sense that the latter ones are not recovered in the non - rotating limit.   the brane configurations are qualitatively different from the spherical problem, except in the special case of a @xmath3-dimensional brane.   furthermore, a quasi - static phase transition between the topologically different solutions can not be studied here, due to the lack of a general, stationary, equatorial solution.
-1 social media platforms are now a key source of information for a large segment of the public. as such, these platforms have a great potential as a means to provide real - time information to emergency management agencies.   moreover, during an emergency, these agencies are very interested in social media as a means to find public - driven response efforts, as well as to track how their handling of that emergency is being perceived. however, there is currently a lack advanced tools designed for monitoring social media during emergencies.   the emergency analysis identification and management system ( eaims ) is a prototype service that aims to fill this technology gap by providing richer analytic and exploration tools than current solutions. in particular, eaims provides real - time detection of emergency events, related information finding, information access and credibility analysis tools for use over social media during emergencies.
atmospheric channels are a promising candidate to establish secure quantum communication on a global scale. however, due to their turbulent nature, it is crucial to understand the impact of the atmosphere on the quantum properties of light and examine it experimentally. in this paper, we introduce a method to test atmospheric free - space links with quantum light on a laboratory scale.   this allows one to probe turbulent quantum channels in a well - controlled manner. to implement this technique  , we perform a series of measurements with different constant attenuations and combine the obtained data to simulate fluctuating losses.   we directly test the proposed method with an on - chip nonclassical light source and a state - of - the - art time - bin multiplexed superconducting nano - wire detection system. with the obtained data, we characterize the nonclassicality of the generated states for different atmospheric noise models and analyze a post - selection protocol.
the object recognition is a complex problem in the image processing.   mathematical morphology is shape oriented operations, that simplify image data, preserving their essential shape characteristics and eliminating irrelevancies.   this paper briefly describes morphological operators using hypergraph and its applications for thinning algorithms.   the morphological operators using hypergraph method is used to preventing errors and irregularities in skeleton, and is an important step recognizing line objects.   the morphological operators using hypergraph such as dilation, erosion, opening, closing is a novel approach in image processing and it act as a filter remove the noise and errors in the images.    * index terms*-mathematical morphology, graphs, hyper graph, alternative sequential filter
based on results of density functional theory ( dft ) calculations with the local spin density approximation ( lsda ) and the generalized gradient approximation ( gga ), we propose a new magnetic material, cscl - type fese.   the calculations reveal the existence of ferromagnetic ( fm ) and antiferromagnetic ( afm ) states over a wide range of lattice constants. at @xmath0 in the gga  , the equilibrium state is found to be afm with a local fe magnetic moment of @xmath1.   a metastable fm state with fe and se local magnetic moments of @xmath2 and @xmath3, respectively, lies @xmath4mev above the afm state.   its equilibrium lattice constant is @xmath5% smaller than that of the afm state, implying that when the system undergoes a phase transition from the afm state to the fm one, the transition is accompanied by volume contraction.   such an afm - fm transition is attributed to spin - density @xmath6-reflection symmetry ; the symmetry driven afm - fm transition is not altered by spin - orbit coupling.   the relative stability of different magnetic phases is discussed in terms of the local density of states.   we find that cscl - type fese is mechanically stable, but the magnetic states are expected to be brittle.   cscl - type fese, first - order magnetic transition, spin - density - reflection symmetry, mechanical stability, electronic structure, first - principles calculations    71.20.be, 74.25.jb, 74.25.ha, 75.25+z
co - doped zno is the prototypical dilute magnetic oxide showing many of the characteristics of ferromagnetism.   the microscopic origin of the long range order however remains elusive, since the conventional mechanisms for the magnetic interaction, such as super - exchange and double exchange, fail either at the fundamental or at a quantitative level. intriguingly, there is a growing evidence that defects both in point - like or extended form play a fundamental role in driving the magnetic order. here   we explore one of such possibilities by performing _   ab initio _ density functional theory calculations for the magnetic interaction of co ions at or near a zno \{10@xmath00 } surface.   we find that extended surface states can hybridize with the @xmath1-levels of co and efficiently mediate the magnetic order, although such a mechanism is effective only for ions placed in the first few atomic planes near the surface.   we also find that the magnetic anisotropy changes at the surface from an hard - axis easy - plane to an easy axis, with an associated increase of its magnitude. we then conclude that clusters with high densities of surfacial co ions may display blocking temperatures much higher than in the bulk.
we present fluid dynamics videos of the flight of some of the smallest insects including the jewel wasp, _ ampulex compressa _, and thrips, _ thysanoptera _   spp.   the fruit fly, _ drosophila melanogaster _, is large in comparison to these insects. while the fruit fly flies at @xmath0, the jewel wasp flies at @xmath1, and thrips flies at @xmath2.   differences in the general structures of the wakes generated by each species are observed.   the differences in the wakes correspond to changes in the ratio of lift forces ( vertical component ) to drag forces ( horizontal component ) generated.   http://manowar.amath.unc.edu/~lam9/movies/miller_largeaps_movie.m4v and http://manowar.amath.unc.edu/~lam9/movies/miller_smallaps_movie.mp4 versions of the movies may be found by clicking the links.
a simple solid - on - solid model, proposed earlier to describe overlayer - induced faceting of bcc(111 ) surface, is applied to faceting of curved surfaces covered by an adsorbate monolayer.   surfaces studied in this paper are formed by a part of sphere around the  pole.   results of monte carlo simulations show that the morphology of a faceted surface depends on the annealing temperature. at an initial stage   the surface around the @xmath0 $ ] pole consists of 3-sided pyramids and step - like facets, then step - like facets dominate and their number decreases with temperature, finally a single big pyramid is formed.   it is shown that there is a reversible phase transition at which a faceted surface transforms to an almost spherical one.   it is found that the temperature of this phase transition is an increasing function of the surface curvature.   simulation results show that measurements of high temperature properties performed directly and after fast cooling down to a low temperature lead to different results.
tissot indicatrices have provided visual measures of local area and isotropy distortions. here   we show how large scale distortions of flexion ( bending ) and skewness ( lopsidedness ) can be measured.   area and isotropy distortions depend on the map projection metric, flexion and skewness, which manifest themselves on continental scales, depend on the first derivatives of the metric.   we introduce new indicatrices that show not only area and isotropy distortions but flexion and skewness as well.   we present a table showing error measures for area, isotropy, flexion, skewness, distances, and boundary cuts allowing us to compare different world map projections.   we find that the winkel - tripel projection ( already adopted for world maps by the national geographic ), has low distortion on most measures and excellent quality overall.   * keywords : * maps, earth, projection, curvature
the propagation of a chemical wave in a narrow, cone - shaped glass capillary was investigated.   when a chemical wave propagates from the wider end to the narrower end, it slows, stops, and then disappears.   a phenomenological model that considers the surface effect of the glass is proposed, and this model reproduces the experimental trends.
systems of particles in a confining potential exhibit a spatially dependent density which fundamentally alters the nature of phase transitions that occur.   a specific instance of this situation, which is being extensively explored currently, concerns the properties of ultra - cold, optically trapped atoms. of interest is how the superfluid - insulator transition is modified by the inhomogeneity, and, indeed, the extent to which a sharp transition survives at all.   this paper explores a classical analog of these systems, the blume - capel model with a spatially varying single ion anisotropy and/or temperature gradient.   we present results both for the nature of the critical properties and for the validity of the  local density approximation " which is often used to model the inhomogeneous case.   we compare situations when the underlying uniform transition is first and second order.
anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells.   the resulting time series are usually evaluated in terms of time averages.   often anomalous diffusion is connected with non - ergodic behaviour. in such cases   the time averages remain random variables and hence irreproducible. here   we present a detailed analysis of the time averaged mean squared displacement for systems governed by anomalous diffusion, considering both unconfined and restricted ( corralled ) motion.   we discuss the behaviour of the time averaged mean squared displacement for two prominent stochastic processes, namely, continuous time random walks and fractional brownian motion.   we also study the distribution of the time averaged mean squared displacement around its ensemble mean, and show that this distribution preserves typical process characteristic even for short time series.   recently, velocity correlation functions were suggested to distinguish between these processes.   we here present analytucal expressions for the velocity correlation functions.   knowledge of the results presented here are expected to be relevant for the correct interpretation of single particle trajectory data in complex systems.
in previous studies, we have examined a resonant excitation of disk oscillations in deformed disks. in these studies, however, mathematical treatment around the resonant points was not rigorous  . in this paper the inadequate point is corrected, with no essential changes in the final results. for this excitation process to work  , disks must be general relativistic.   that is, the non - monotonic radial distribution of epicyclic frequency in relativistic disks is essential for the presence of the resonance and for trapping of oscillations. in this paper, the growth rate of resonant oscillations is expressed in a form more suitable for numerical calculations.
a fundamental problem for the delay and backlog analysis across multi - hop paths in wireless networks is how to account for the random properties of the wireless channel. since the usual statistical models for radio signals in a propagation environment   do not lend themselves easily to a description of the available service rate, the performance analysis of wireless networks has resorted to higher - layer abstractions, e.g., using markov chain models. in this work,   we propose a network calculus that can incorporate common statistical models of fading channels and obtain statistical bounds on delay and backlog across multiple nodes.   we conduct the analysis in a transfer domain, which we refer to as the _ snr domain _  , where the service process at a link is characterized by the instantaneous signal - to - noise ratio at the receiver.   we discover that, in the transfer domain, the network model is governed by a dioid algebra, which we refer to as  algebra. using this algebra   we derive the desired delay and backlog bounds.   an application of the analysis is demonstrated for a simple multi - hop network with rayleigh fading channels.
we argue that, within a broad class of extensions of the standard model, there is a tight corellation between the dynamics of the electroweak phase transition and the cubic self - coupling of the higgs boson : models which exhibit a strong first - order ewpt predict a large deviation of the higgs self - coupling from the standard model prediction, as long as no accidental cancellations occur.   order - one deviations are typical  . this shift would be observable at the large hadron collider if the proposed luminosity or energy upgrades are realized, as well as at a future electron - positron collider such as the proposed international linear collider.   these measurements would provide a laboratory test of the dynamics of the electroweak phase transition.   1.5 cm    * higgs self - coupling as a probe of +.4 cm electroweak phase transition *.8 cm    * andrew noble and maxim perelstein *   +    _ institute for high energy phenomenology + newman laboratory of elementary particle physics, + cornell university, ithaca, ny 14853, usa _   +    0.3truecm
the @xmath0-nucleon ( @xmath0n ) interactions are deduced from the heavy baryon chiral perturbation theory up to the next - to - leading - order terms. combining the relativistic mean - field theory for nucleon system,   we have studied the in - medium properties of @xmath0-meson.   we find that all the elastic scattering @xmath0n interactions come from the next - to - leading - order terms.   the @xmath1n sigma term is found to be about 280@xmath2130 mev.   the off - shell terms are also important to the in - medium properties of @xmath0-meson. on application of the latest determination of the @xmath0n scattering length,   the ratio of @xmath0-meson effective mass to its vacuum value is near @xmath3, while the optical potential is about @xmath4 mev, at the normal nuclear density.
clustering and correlation effects are frequently observed in chaotic systems in situations where, because of the positivity of the lyapunov exponents, no dimension reduction is to be expected. in this paper, using a globally coupled network of bernoulli units, one finds a general mechanism by which strong correlations and slow structures are obtained at the synchronization edge.   a structure index is defined, which diverges at the transition points.   some conclusions are drawn concerning the construction of an ergodic theory of self - organization.
we outline a model for a cognitive epigenetic system based on elements of the shannon theory of information and the statistical physics of the generalized onsager relations.   particular attention is paid to the concept of the rate distortion function and from another direction as motivated by the thermodynamics of computing, the fundamental homology with the free energy density of a physical system.   a unifying aspect of the dynamic framework involves the concept of a groupoid and of a groupoid atlas. from a stochastic differential equation we postulate a multidimensional it process for an epigenetic system from which a stochastic flow may permeate through components of this atlas.   * key words * rate distortion function, epigenetic system, free energy density, groupoid, onsager relations, it process.
model lattices consisting of balls connected by central - force springs provide much of our understanding of mechanical response and phonon structure of real materials.   their stability depends critically on their coordination number @xmath0.   @xmath1-dimensional lattices with @xmath2 are at the threshold of mechanical stability and are _ isostatic_. lattices with @xmath3 exhibit zero - frequency  floppy " modes that provide avenues for lattice collapse.   the physics of systems as diverse as architectural structures, network glasses, randomly packed spheres, and biopolymer networks is strongly influenced by a nearby isostatic lattice.   we explore elasticity and phonons of a special class of two - dimensional isostatic lattices constructed by distorting the kagome lattice.   we show that the phonon structure of these lattices, characterized by vanishing bulk moduli and thus negative poisson ratios and auxetic elasticity, depends sensitively on boundary conditions and on the nature of the kagome distortions.   we construct lattices that under free boundary conditions exhibit surface floppy modes only or a combination of both surface and bulk floppy modes ; and we show that bulk floppy modes present under free boundary conditions are also present under periodic boundary conditions but that surface modes are not. in the the long - wavelength limit, the elastic theory of all these lattices is a conformally invariant field theory with holographic properties, and the surface waves are rayleigh waves.   we discuss our results in relation to recent work on jammed systems.   our results highlight the importance of network architecture in determining floppy - mode structure.
we calculate orbital spin - dependent magnetization in a two - dimensional electron gas with spin - orbit interaction of rashba type.   such an orbital magnetization is admitted by the time - reversal symmetry of the system, and gives rise to spin currents when the system is not in thermal equilibrium.   the theoretical approach is based on the linear response theory and the matsubara green s function formalism. to account for the spin - resolved orbital magnetization   a spin - dependent vector potential has been introduced.   the spin currents which appear in thermal nonequilibrium due to the spin - resolved orbital magnetization play an important role in the spin nernst effect, and have to be included in order to correctly describe the low - temperature spin nernst conductivity.
we present new photometric observations in the @xmath0 bands of the double - lined eclipsing binary bd@xmath1706 conducted over three observing seasons, as well as new x - ray observations obtained with the rosat satellite covering a full orbital cycle ( @xmath2  days ).   a detailed light - curve analysis of the optical data shows the system to be semidetached, confirming indications from an earlier analysis by @xcite, with the less massive and cooler star filling its roche lobe.   the system is a member of the rare class of cool algol systems, which are different from the  classical " algol systems in that the mass - gaining component is also a late - type star rather than a b- or a - type star. by combining the new photometry with a reanalysis of the spectroscopic observations reported by @xcite we derive accurate absolute masses for the components of @xmath3  m@xmath4 and @xmath5  m@xmath4, radii of @xmath6  r@xmath4 and @xmath7  r@xmath4, as well as effective temperatures of @xmath8  k and @xmath9  k for the primary and secondary, respectively.   there are obvious signs of activity ( spottedness ) in the optical light curve of the binary.   our x - ray light curve clearly shows the primary eclipse but not the secondary eclipse, suggesting that the primary star is the dominant source of the activity in the system.   the depth and duration of the eclipse allow us to infer some of the properties of the x - ray emitting region around that star.
an orbitope is the convex hull of an orbit of a compact group acting linearly on a vector space.   these highly symmetric convex bodies lie at the crossroads of several fields including convex geometry, algebraic geometry, and optimization.   we present a self - contained theory of orbitopes with particular emphasis on instances arising from the groups @xmath0 and @xmath1.   these include schur - horn orbitopes, tautological orbitopes, carathodory orbitopes, veronese orbitopes, and grassmann orbitopes.   we study their face lattices, their algebraic boundaries, and representations as spectrahedra or projected spectrahedra.
we study an m - theory solution for the holographic flow of ads@xmath0 times sasaki - einstein 7-manifolds with skew - whiffing, perturbed by a mass operator.   the infrared solution contains the 5 dimensional schrdinger geometry after considering the gravity dual of the standard non - relativistic limit of relativistic field theories.   the mass deformation of the field theory is discussed in detail for the case with 7 manifold being a round sphere.   +   +    * emergent schrdinger geometries from mass - deformed cft *    hee - cheol kim@xmath1, seok kim@xmath1, kimyeong lee@xmath2 and jaemo park@xmath3    _ @xmath1department of physics and astronomy & center for theoretical physics, + seoul national university, seoul 151 - 747, korea. _   +    _ @xmath2school of physics, korea institute for advanced study, seoul 130 - 012, korea.   _ +    _ @xmath3department of physics & center for theoretical physics ( pctp ), + postech, pohang 790 - 784, korea. _ +
we numerically evaluate the casimir interaction energy for configurations involving two perfectly conducting eccentric cylinders and a cylinder in front of a plane.   we consider in detail several special cases. for quasi - concentric cylinders,   we analyze the convergence of a perturbative evaluation based on sparse matrices. for concentric cylinders,   we obtain analytically the corrections to the proximity force approximation up to second order, and we present an improved numerical procedure to evaluate the interaction energy at very small distances. finally, we consider the configuration of a cylinder in front of a plane.   we first show numerically that, in the appropriate limit, the casimir energy for this configuration can be obtained from that of two eccentric cylinders.   then we compute the interaction energy at small distances, and compare the numerical results with the analytic predictions for the first order corrections to the proximity force approximation.
one of the most important aims of the fields of robotics, artificial intelligence and artificial life is the design and construction of systems and machines as versatile and as reliable as living organisms at performing high level human - like tasks.   but how are we to evaluate artificial systems if we are not certain how to measure these capacities in living systems, let alone how to define life or intelligence? here   i survey a concrete metric towards measuring abstract properties of natural and artificial systems, such as the ability to react to the environment and to control one s own behaviour.   + * keywords : * _ natural computing ; systems behaviour ; controllability ; programmability ; turing test ; compressibility ; kolmogorov complexity ; randomness ; robotics ; artificial life _
we use the subgraph replacement method to investigate new properties of regions on the square lattice with diagonals drawn in.   in particular, we show that cyclically symmetric tilings of a generalization of the aztec diamond are always enumerated by a simple product formula.   we also prove an explicit product formula for the number of cyclically symmetric tilings of a quasi - hexagon.   * keywords : * perfect matchings, hybrid domino - lozenge tilings, dual graph, subgraph replacement.
surveys of the distant universe have been made using the scuba submillimeter(submm)-wave camera at the jcmt. 450- and   850-@xmath0 m data is taken simultaneously by scuba in the same 5-arcmin@xmath1 field.   deep 850-@xmath0 m counts of high - redshift dusty galaxies have been published ; however, at 450@xmath0 m both the atmospheric transmission and antenna efficiency are lower, and the atmospheric noise is higher, and so only upper limits to the 450-@xmath0 m counts have been reported so far. here   we apply the methods used by blain et al.   ( 1999 ) to derive deep 850-@xmath0 m counts from scuba images of lensing clusters to the 450-@xmath0 m images that were obtained in parallel, in which four sources were detected.   we present the first 450-@xmath0 m galaxy count.   this analysis has only just become possible because the volume of data and the difficulty of calibration are both greater for the 450-@xmath0 m array. in light of recent work,   in which the identification of two of the galaxies in our sample was clarified, we also update our deep 850-@xmath0 m counts.
we present a next - to - leading order calculation for the virtual photoproduction of one and two jets in @xmath0 collisions.   soft and collinear singularities are extracted using the phase space slicing method.   the collinear photon initial state singularity depends logarithmically on the mass of the virtual photon and is absorbed into the virtual photon structure function.   an @xmath1 factorization scheme is defined similarly to the real photon case.   numerical results are presented for hera conditions using the snowmass jet definition for inclusive single jet and dijet cross sections.   we study the dependence of these cross sections on the transverse energies and rapidities of the jets.   finally, we compare the ratio of the experimentally defined resolved and direct cross sections with recent zeus data as a function of the photon virtuality @xmath2.
we have developed a software library for chemical evolution simulations of galaxy formation under the simple stellar population ( ssp ) approximation. in this library,   all of the necessary components concerning chemical evolution, such as initial mass functions, stellar lifetimes, yields from type ii and ia supernovae, asymptotic giant branch stars, and neutron star mergers, are compiled from the literature.   various models are pre - implemented in this library so that users can choose their favorite combination of models.   subroutines of this library return released energy and masses of individual elements depending on a given event type. since the redistribution manner of these quantities depends on the implementation of users simulation codes, this library leaves it up to the simulation code. as demonstrations, we carry out both one - zone, closed box simulations and three - dimensional simulations of a collapsing gas and dark matter system using this library. in these simulations  , we can easily compare the impact of individual models on the chemical evolution of galaxies, just by changing the control flags and parameters of the library.   since this library only deals with the part of chemical evolution under the ssp approximation, any simulation codes that use the ssp approximation   namely particle - base and mesh codes, as well as semi - analytical models  can use it. this library is named `` celib '' after the term `` chemical evolution library '' and is made available to the community.
the structure of events in high - energy collisions is complex and not predictable from first principles.   event generators allow the problem to be subdivided into more manageable pieces, some of which can be described from first principles, while others need to be based on appropriate models with parameters tuned to data. in these lectures   we provide an overview, discuss how matrix elements are used, introduce the machinery for initial- and final - state parton showers, explain how matrix elements and parton showers can be combined for optimal accuracy, introduce the concept of multiple parton   parton interactions, comment briefly on the hadronization issue, and provide an outlook for the future.   hep - ph/0611247 + cern - lcgapp-2006 - 06 + november 2006 +
we discuss general thermodynamic properties of molecular structure formation processes like protein folding by means of simplified, coarse - grained models.   the conformational transitions accompanying these processes exhibit similarities to thermodynamic phase transitions, but also significant differences as the systems that we investigate here are very small. the usefulness of a microcanonical statistical analysis of these transitions in comparison with a canonical interpretation is emphasized.   the results are obtained by employing sophisticated generalized - ensemble markov - chain monte carlo methodologies.
under the action of an alternating perpendicular magnetic field the polarity of the vortex state nanodisk can be efficiently switched.   we predict the regular and _ chaotic _ dynamics of the vortex polarity and propose a simple analytical description in terms of a _ reduced vortex core _ model.   conditions for the controllable polarity switching are analyzed.
calculations carried out to model the evolution of star 32 under different assumptions about the stellar wind mass - loss rate provide robust limits on the present mass of the star.   the obtained range is 31 to 35.5 m@xmath0, which is in very good agreement with the orbital solution of orosz et al., namely 28.3 to 35.3 m@xmath0.   the initial mass of star 32 had to be in the range 35 to 40 m@xmath0 and the present age of the system is 3.7 to 4.0 myr.       binaries : general  stars : evolution  stars : individual : lmc x-1  stars : massive  x - rays : binaries.
we discuss evidence that quasars, and more generally radio jets, may have played an active role in the formation stage of galaxies by inducing star formation, i.e. through positive feedback.   this mechanism first proposed in the 70 s has been considered as anecdotic until now, contrary to the opposite effect that is generally put forward, the quenching of star formation in massive galaxies to explain the galaxy bimodality, downsizing and the universal black hole mass over bulge stellar mass ratio.   this suggestion is based on the recent discovery of an ultra - luminous infrared galaxies, i.e. an extreme starburst, which appears to be triggered by a radio jet from the qso he0450@xmath02958 at @xmath1=0.2863, together with the finding in several systems of an offset between molecular gas and quasars, which may be explained by the positive feedback effect of radio jets on their local environment.
since observation on a quantum system may cause the system state collapse, it is usually hard to find a way to monitor a quantum process, which is a quantum system that continuously evolves.   we propose a protocol that can debug a quantum process by monitoring, but not disturb the evolution of the system.   this protocol consists of an error detector and a debugging strategy.   the detector is a projection operator that is orthogonal to the anticipated system state at a sequence of time points, and the strategy is used to specify these time points. as an example, we show how to debug the computational process of quantum search using this protocol. by applying the skolem   mahler   lech theorem in algebraic number theory, we find an algorithm to construct all of the debugging protocols for quantum processes of time independent hamiltonians.
parity violating elastic electron - nucleus scattering provides an accurate and model independent measurement of neutron densities, because the @xmath0 couples primarily to neutrons.   coulomb distortion corrections to the parity violating asymmetry @xmath1 are calculated exactly using a relativistic optical model.   distortions significantly reduce @xmath1 in a heavy nucleus.   however even with distortions, an experiment to measure the neutron radius is feasible.   this will aid the interpretation of future atomic parity violation measurements and provide fundamental nuclear structure information.   coulomb distortions and small differences between neutron and proton radii could be important for a standard model test on @xmath2he, @xmath3c or @xmath4o.
we study observables sensitive to tensor structure of interactions of a hypothetical heavy spin-0 particle.   it is assumed that the interactions of this particle are primary with photons ; interactions with vector bosons @xmath0, @xmath1, @xmath2, and quarks @xmath3 are suppressed.   the above assumptions favor the production of this hypothetical particle through the vector boson fusion mechanism structurally dominated by @xmath4 and @xmath5 interactions.   this particle will be produced in association with two light quarks.   it is shown that the difference in azimuthal angle between the tagging jets provides an observable sensitive to the cp properties of this hypothetical particle.   bsm, heavy particle, tensor structure, extended higgs sector, photon, jets, vbf, cp
in the past many papers have appeared which simulated surface growth with different growth models.   the results showed that, if models differed only slightly in their ` growth'rules, the resulting surfaces may belong to different universality classes, i.e. they are described by different differential equations. in the present paper   we describe a mapping of `` growth rules '' to differential operators and give plausibility arguments for this mapping.   we illustrate the validity of our theory by applying it to published results.
the electrical resistivity, thermoelectric power and electronic thermal conductivity of simple ( isotropic ) metals are studied in a uniform way. starting from results of a variational solution of the boltzmann equation, a generalized matthiessen rule is used in order to superpose the inelastic ( or not ) electron - phonon and elastic electron - impurity scattering cross sections ( `` matrix elements '' ). the temperature dependence relative to these processes   is given through simple functions and physical parameters over the usually investigated range of temperature for each transport coefficient.   the coherence of such results is emphasized.   = 220 mm = 160 mm    0.5 cm pacs05.60.+w, 17.15.jf, 44.90.+c
bose - einstein condensation ( bec ) of composite diquarks in quark matter ( the color superconductor phase ) is discussed using the quasi - chemical equilibrium theory at a relatively low density region near the deconfinement phase transition, where dynamical quark - pair fluctuations are assumed to be described as bosonic degrees of freedom ( diquarks ).   a general formulation is given for the diquark formation and particle - antiparticle pair - creation processes in the relativistic framework, and some interesting properties are shown, which are characteristic for the relativistic many - body system.   behaviors of transition temperature and phase diagram of the quark - diquark matter are generally presented in model parameter space, and their asymptotic behaviors are also discussed. as an application to the color superconductivity,   the transition temperatures and the quark and diquark density profiles are calculated in case with constituent / current quarks, where the diquark is in bound / resonant state.   we obtained @xmath0 for constituent quarks and @xmath1 for current quarks at a moderate density ( @xmath2 ).   the method is also developed to include interdiquark interactions into the quasi - chemical equilibrium theory within a mean - field approximation, and it is found that a possible repulsive diquark - diquark interaction lowers the transition temperature by @xmath3.   + pacs numbers : 12.38.-t, 12.38.mh, 12.38.lg, 03.75.nt
we examine the hypothesis that magnetic fields are inflating the radii of fully convective main sequence stars in detached eclipsing binaries ( debs ).   the magnetic dartmouth stellar evolution code is used to analyze two systems in particular : kepler-16 and cm draconis.   magneto - convection is treated assuming stabilization of convection and also by assuming reductions in convective efficiency due to a turbulent dynamo.   we find that magnetic stellar models are unable to reproduce the properties of inflated fully convective main sequence stars, unless strong interior magnetic fields in excess of 10  mg are present.   validation of the magnetic field hypothesis given the current generation of magnetic stellar evolution models therefore depends critically on whether the generation and maintenance of strong interior magnetic fields is physically possible.   an examination of this requirement is provided.   additionally, an analysis of previous studies invoking the influence of star spots is presented to assess the suggestion that star spots are inflating stars and biasing light curve analyses toward larger radii. from our analysis  , we find that there is not yet sufficient evidence to definitively support the hypothesis that magnetic fields are responsible for the observed inflation among fully convective main sequence stars in debs.
the specific behavior of spinor field in curve space - time with the exception of frw model almost always gives rise to non - trivial non - diagonal components of the energy - momentum tensor.   this non - triviality of non - diagonal components of the energy - momentum tensor imposes some severe restrictions either on the spinor field or on the metric functions. in this paper within the scope of an anisotropic bianchi type - i universe we study the role of spinor field in the evolution of the universe.   it is found that there exist two possibilities. in one scenario   the initially anisotropic universe evolves into an isotropic one asymptotically, but in this case the spinor field itself undergoes some severe restrictions. in the second scenario   the isotropization takes places almost at the beginning of the process.    -24pt
it has been observed that exact solutions for electromagnetic ( em ) excitations of the kerr - schild ( ks ) geometry form outgoing beams which have very strong back reaction to metric and break the black hole horizon. as a result,   interaction of a black hole with nearby electromagnetic field and electromagnetic vacuum has to cover the horizon by a set of fluctuating microholes.   we integrate and analyze the debney - kerr - schild equations for electromagnetic excitations of a black - hole and obtain that the exact solutions for outgoing radiation contain two related but radically different components which shed light on a possible semi - classical mechanism of black - hole evaporation : a ) first component consists of the singular beam pulses which perforate horizon, breaking its impenetrability, and b ) another component is regular and responsible for the loss of mass similar to the known vaidya ` shining star'radiation.   we show also that the mysterious twosheeted twistor structure of the kerr - schild geometry corresponds to a holographic structure of quantum black hole spacetimes predicted by stephens, t hooft and whiting. the resulting kerr - schild geometry of fluctuating twistor - beams takes an intermediate position between the classical and quantum gravity.   ~ 3|y_,3 3y_,3 `
we develop a perturbative approach that allows one to study the surface scattering in quasi-1d waveguides with rough boundaries.   our approach is based on the construction of an effective `` bulk '' potential of a very complicated structure.   the detailed analysis of this potential reveals that apart from the well known terms considered in the previous studies, one should keep specific terms that depend on the square of the derivative of the boundaries. as was found, in spite of an apparent smallness of these _ square - gradient scattering _   ( sgs ) terms, there is a physically important region of parameters, in which they can not be neglected.   our approach also demonstrates that the contribution of the sgs - mechanism of scattering strongly depends on the type of the rough boundaries ( uncorrelated, symmetric or antisymmetric ).
spatial awareness in mammals is based on an internalized representation of the environment, encoded by large networks of spiking neurons.   while such representations can last for a long time, the underlying neuronal network is transient : neuronal cells die every day, synaptic connections appear and disappear, the networks constantly change their architecture due to various forms of synaptic and structural plasticity. how can a network with a dynamic architecture encode a stable map of space? we address this question using a physiological model of a `` flickering '' neuronal network and demonstrate that it can maintain a robust topological representation of space.
we propose a new way to detect individual bright ultra - high energy cosmic ray ( uhecr ) sources above background if the galactic magnetic field ( gmf ) gives the main contribution to uhecr deflections  @xcite.   this method can be directly applied to maps given by experiments.   it consists in starting from at least two high energy events above 6@xmath010@xmath1ev, and looking at lower energy tails.   we test the efficiency of the method and investigate its dependence on different parameters. in case of detection, the source position and the local gmf deflection power are reconstructed.   both reconstructions are strongly affected by the turbulent gmf. with the parameters adopted in this study, for 68% of reconstructed sources,   the angular position is less than one degree from the real one. for typical turbulent field strengths of 4@xmath2 g at the earth position and 1.5kpc extension in the halo  , one can reconstruct the deflection power with 25% precision in 68% of cases.   ultra - high energy cosmic rays, magnetic fields, galaxy.
we propose a class of models which generate three - dimensional random volumes, where each configuration consists of triangles glued together along multiple hinges.   the models have matrices as the dynamical variables and are characterized by semisimple associative algebras @xmath0.   although most of the diagrams represent configurations which are not manifolds, we show that the set of possible diagrams can be drastically reduced such that only ( and all of the ) three - dimensional manifolds with tetrahedral decompositions appear, by introducing a color structure and taking an appropriate large @xmath1 limit. we examine the analytic properties when @xmath0 is a matrix ring or a group ring, and show that the models with matrix ring have a novel strong - weak duality which interchanges the roles of triangles and hinges.   we also give a brief comment on the relationship of our models with the colored tensor models.   kuns-2547     * random volumes from matrices *    masafumi fukuma, sotaro sugishita and naoya umeda    0.8 cm _ department of physics, kyoto university, kyoto 606 - 8502, japan _ 1.2 cm
this paper deals with chain graphs under the classic lauritzen - wermuth - frydenberg interpretation. we prove that the regular gaussian distributions that factorize with respect to a chain graph @xmath0 with @xmath1 parameters have positive lebesgue measure with respect to @xmath2, whereas those that factorize with respect to @xmath0 but are not faithful to it have zero lebesgue measure with respect to @xmath2.   this means that, in the measure - theoretic sense described, almost all the regular gaussian distributions that factorize with respect to @xmath0 are faithful to it.
we show that a conformal - invariant dark sector, interacting conformally with the standard model ( sm ) fields through the higgs portal, provides a viable framework where cold dark matter ( cdm ) and invisible higgs decays can be addressed concurrently.   conformal symmetry naturally subsumes the @xmath0 symmetry needed for stability of the cdm.   it also guarantees that the weaker the couplings of the dark sector fields to the sm higgs field, the smaller the masses they acquire through electroweak breaking.   the model comfortably satisfies the bounds from large hadron collider ( lhc ) and planck space telescope ( planck 2013 ).   dark matter, conformal symmetry, relic density
the results of multi - epoch observations of the southern starburst galaxy, ngc  253, with the australian long baseline array ( lba ) at 2.3  ghz are presented. as with previous radio   interferometric observations of this galaxy, no new sources were discovered. by combining the results of this survey with very large array observations at higher frequencies from the literature,   spectra were derived and a free - free absorption model was fitted of 20 known sources in ngc  253.   the results were found to be consistent with previous studies.   the supernova remnant, 5.48@xmath043.3, was imaged with the highest sensitivity and resolution to date, revealing a two - lobed morphology.   comparisons with previous observations of similar resolution give an upper limit of @xmath1  km  s@xmath2 for the expansion speed of this remnant.   we derive a supernova rate of @xmath30.2  yr@xmath2 for the inner 300  pc using a model that improves on previous methods by incorporating an improved radio supernova peak luminosity distribution and by making use of multi - wavelength radio data spanning 21 years.   a star formation rate of @xmath4  yr@xmath2 was also estimated using the standard relation between supernova and star - formation rates.   our improved estimates of supernova and star - formation rates are consistent with studies at other wavelengths.   the results of our study point to the possible existence of a small population of undetected supernova remnants, suggesting a low rate of radio supernovae production in ngc  253.
we present analytical solutions of the geodesic equations of test particles and light in the five dimensional singly spinning black ring spacetime for special cases, since it does not appear possible to separate the hamilton - jacobi - equation for singly spinning black rings in general.   based on the study of the polynomials in the equations of motion we characterize the motion of test particles and light and discuss the associated orbits.
we review the current status of spin - averaged and spin - dependent parton distribution functions ( pdfs ) of the nucleon. after presenting the formalism used to fit pdfs in modern global data analyses,   we discuss constraints placed on the pdfs by specific data types.   we give representative examples of unpolarized and polarized pdfs and their errors, and list open questions in global qcd fitting.   finally, we anticipate how future facilities, with fixed - target and collider experiments, may impact our knowledge of pdfs and reduce their uncertainties.
two of the key issues in understanding the neutron - to - proton ratio in a core - collapse supernova are discussed.   one of these is the behavior of the neutrino - nucleon cross sections as supernova energies.   the other issue is the many - body properties of the neutrino gas near the core when both one- and two - body interaction terms are included.
in optimizing the topology of wireless networks built of a dynamic set of spatially embedded agents, there are many trade - offs to be dealt with.   the network should preferably be as small ( in the sense that the average, or maximal, pathlength is short ) as possible, it should be robust to failures, not consume too much power, and so on. in this paper, we investigate simple models of how agents can choose their neighbors in such an environment. in our model of attachment, we can tune from one situation where agents prefer to attach to others in closest proximity, to a situation where distance is ignored ( and thus attachments can be made to agents further away ).   we evaluate this scenario with several performance measures and find that the optimal topologies, for most of the quantities, is obtained for strategies resulting in a mix of most local and a few random connections.
we present a catalog of near - infrared ( nir ) spectra and associated measurements for 886 nearby m dwarfs.   the spectra were obtained with the nasa - infrared telescope facility spex spectrograph during a two - year observing campaign ; they have high signal - to - noise ratios ( snr @xmath0 ), span 0.8 - 2.4 @xmath1 m and have @xmath2.   our catalog of measured values contains useful t@xmath3 and composition - sensitive features, empirical stellar parameter measurements, and kinematic, photometric, and astrometric properties compiled from the literature.   we focus on measures of m dwarf abundances (  and  ), capitalizing on the precision of recently published empirical nir spectroscopic calibrations.   we explore systematic differences between different abundance calibrations, and to other similar m dwarf catalogs.   we confirm that the m dwarf abundances we measure show the expected inverse dependence with kinematic, activity, and color - based age indicators.   finally, we provide updated  and  for 16 m dwarf planet hosts.   this catalog represents the largest published compilation of nir spectra and associated parameters for m dwarfs.   it provides a rich and uniform resource for the nearby m dwarfs, and will be especially valuable for measuring habitable zone locations and comparative abundances of the m dwarf planet hosts that will be uncovered by upcoming exoplanet surveys.
based on a semiclassical expansion for quantum chromodynamics in the instanton liquid background, the correlation function of the @xmath0 scalar glueball current is given, and the properties of the @xmath0 scalar glueball are studied in the framework of gaussian sum rules.   besides the pure classical and quantum contributions, the contributions arising from the interactions between the classical instanton fields and quantum gluons are come into play. instead of the usual zero - width approximation for the resonance, the breit - wigner form for the spectral function of the finite - width resonance   is adopted.   the family of the gaussian sum rules for the scalar glueball in quantum chromodynamics with and without light quarks is studied.   a consistency between the subtracted and unsubtracted sum rules is very well justified, and the values of the decay width and the coupling to the corresponding current for the @xmath0 resonance, in which the scalar glueball fraction is dominant, are obtained.
in this paper, we present an analysis of the dynamics and segregation of galaxies in rich clusters from z@xmath00.32 to z@xmath00.48 taken from the cfht optical pdcs ( cop ) survey and from the cnoc survey ( carlberg et al.   1997 ).   our results from the cop survey are based upon the recent observational work of adami et al.   ( 2000a ) and holden et al.   ( 2000 ) and use new spectroscopic and photometric data on six clusters selected from the palomar distant cluster survey ( pdcs ; postman et al. 1996 ).   we have compared the cop and cnoc samples to the eso nearby abell cluster survey ( enacs : z@xmath00.07 ).   our sample shows that the @xmath1 clusters have the same velocity dispersion versus magnitude, morphological type and radius relationships as nearby ( @xmath2 ) abell clusters.   the z@xmath00.48 clusters exhibit, however, departures from these relations. furthermore, there appears to be a higher fraction of late  type ( or bluer, e.g. butcher and oemler, 1984 ) galaxies in the distant clusters compared to the nearby ones.   the classical scenario in which massive galaxies virialize before they evolve from late into early type explain our observations.   in such a scenario, the clusters of our sample began to form before a redshift of approximately 0.8 and the late  type galaxy population had a continuous infall into the clusters.   galaxies : clusters : general  cosmology : observations  cosmology : large scale structure of universe
for real world systems, nonuniform medium is ubiquitous. therefore, we investigate the diffusion - limited - aggregation process on a two dimensional directed small - world network instead of regular lattice. the network structure is established by rewiring connections on the two dimensional directed lattice.   those rewired edges are controlled by two parameters @xmath0 and @xmath1, which characterize the spatial length and the density of the long - range connections, respectively.   simulations show that there exists a maximum value of the fractal dimension when @xmath0 equals zero.   interestingly, we find that the symmetry of the aggregation pattern is broken when rewired connections are long enough, which may be an explanation for the formation of asymmetrical fractal in nature.   then, we perform multifractal analysis on the patterns further.
kinetically constrained spin models are known to exhibit dynamical behavior mimicking that of glass forming systems.   they are often understood as coarse - grained models of glass formers, in terms of some `` mobility '' field.   the identity of this `` mobility '' field has remained elusive due to the lack of coarse - graining procedures to obtain these models from a more microscopic point of view.   here we exhibit a scheme to map the dynamics of a two - dimensional soft disc glass former onto a kinetically constrained spin model, providing an attempt at bridging these two approaches.
it has been recently pointed out that local volume fluctuations in granular packings follow remarkably well a shifted and rescaled gamma distribution named the _ kgamma _ distribution [ t. aste, t. di matteo, phys.   rev.   e 77 ( 2008 ) 021309 ]. in this paper   we confirm, extend and discuss this finding by supporting it with additional experimental and simulation data.   address = school of physical sciences, university of kent, canterbury, kent, ct2 7nh, uk.  , altaddress = department of applied mathematics, research school of physical sciences and engineering, the australian national university, 0200 canberra, act, australia.  , altaddress = king s college department of mathematics, strand london wc2r 2ls, uk.    address = csiro mathematical and information sciences, private bag 33, clayton south, vic, 3168, australia.   address = king s college department of mathematics, strand london wc2r 2ls, uk.
we consider a system where localized bound electron pairs form an array of `` andreev''-like scattering centers and are coupled to a fermionic subsystem of uncorrelated electrons. by means of a path - integral approach,   which describes the bound electron pairs within a coherent pseudospin representation, we derive and analyze the effective action for the collective phase modes which arise from the coupling between the two subsystems once the fermionic degrees of freedom are integrated out.   this effective action has features of a quantum phase model in the presence of a berry phase term and exhibits a coupling to a field which describes at the same time the fluctuations of density of the bound pairs and those of the amplitude of the fermion pairs. due to the competition between the local and   the hopping induced non - local phase dynamics it is possible, by tuning the exchange coupling or the density of the bound pairs, to trigger a transition from a phase ordered superconducting to a phase disordered insulating state.   we discuss the different mechanisms which control this occurrence and the eventual destruction of phase coherence both in the weak and strong coupling limit.
common - path digital in - line holography is considered as a valuable 3d diagnostic techniques for a wide range of applications.   this configuration is cost effective and relatively immune to variation in the experimental environment.   nevertheless, due to its common - path geometry, the signal to noise - ratio of the acquired hologram is weak as most of the detector ( i.e. ccd / cmos sensor ) dynamics is occupied by the reference field signal, whose energy is orders of magnitude higher than the field scattered by the imaged object. as it is intrinsically impossible to modify the ratio of energy of reference to the object field, we propose a co - design approach ( optics / data processing ) to tackle this issue.   the reference to object field ratio is adjusted by adding a 4-f device to a conventional in - line holographic set - up, making it possible to reduce the weight of the reference field while keeping the object field almost constant.   theoretical analysis of the crmer - rao lower bounds of the corresponding imaging model illustrate the advantages of this approach.   these lower bounds can be asymptotically reached using a parametric inverse problems reconstruction.   this implementation results in a @xmath0 gain in axial localization accuracy ( for of 100@xmath1 diameter spherical objects ) compared to a classical in - line holography set - up.
this study presents a wide - field near - infrared ( k - band ) survey in two fields ; sa 68 and lynx 2.   the survey covers an area of 0.6 deg.@xmath0, complete to k=16.5.   a total of 867 galaxies are detected in this survey of which 175 have available redshifts.   the near - infrared number counts to k=16.5 mag. are estimated from the complete photometric survey and are found to be in close agreement with other available studies.   the sample is corrected for incompleteness in redshift space, using selection function in the form of a fermi - dirac distribution.   this is then used to estimate the local near - infrared luminosity function of galaxies.   a schechter fit to the infrared data gives : m@xmath1, @xmath2 and @xmath3 mpc@xmath4 ( for h@xmath5 km / sec / mpc and q@xmath6 ).   when reduced to @xmath7, this agrees with other available estimates of the local irlf.   we find a steeper slope for the faint - end of the infrared luminosity function when compared to previous studies.   this is interpreted as due to the presence of a population of faint but evolved ( metal rich ) galaxies in the local universe.   however, it is not from the same population as the faint blue galaxies found in the optical surveys.   the characteristic magnitude ( @xmath8 ) of the local irlf indicates that the bright red galaxies ( @xmath9 mag. )   have a space density of @xmath10 mpc@xmath4 and hence, are not likely to be local objects.
we investigate the existence and the properties of fully separable ( fully factorized ) ground states in quantum spin systems.   exploiting techniques of quantum information and entanglement theory we extend a recently introduced method and construct a general, self - contained theory of ground state factorization in frustration free quantum spin models defined on lattices in any spatial dimension and for interactions of arbitrary range.   we show that, quite generally, non exactly solvable translationally invariant models in presence of an external uniform magnetic field can admit exact, fully factorized ground state solutions.   unentangled ground states occur at finite values of the hamiltonian parameters satisfying well defined balancing conditions between the applied field and the interaction strengths.   these conditions are analytically determined together with the type of magnetic orderings compatible with factorization and the corresponding values of the fundamental observables such as energy and magnetization.   the method is applied to a series of examples of increasing complexity, including translationally - invariant models with short, long, and infinite ranges of interaction, as well as systems with spatial anisotropies, in low and higher dimensions.   we also illustrate how the general method, besides yielding a large series of novel exact results for complex models in any dimension, recovers, as particular cases, the results previously achieved on simple models in low dimensions exploiting direct methods based on factorized mean - field ansatz.
we have studied the radial distribution of the early ( e / s0 ) and late ( s / irr ) types of satellites around bright host galaxies.   we made a volume - limited sample of 4,986 satellites brighter than @xmath0 associated with 2,254 hosts brighter than @xmath1 from the sdss dr5 sample.   the morphology of satellites is determined by an automated morphology classifier, but the host galaxies are visually classified.   we found segregation of satellite morphology as a function of the projected distance from the host galaxy.   the amplitude and shape of the early - type satellite fraction profile are found to depend on the host luminosity.   this is the morphology - radius / density relation at the galactic scale.   there is a strong tendency for morphology conformity between the host galaxy and its satellites.   the early - type fraction of satellites hosted by early - type galaxies is systematically larger than that of late - type hosts, and is a strong function of the distance from the host galaxies.   fainter satellites are more vulnerable to the morphology transformation effects of hosts.   dependence of satellite morphology on the large - scale background density was detected.   the fraction of early - type satellites increases in high density regions for both early and late - type hosts.   it is argued that the conformity in morphology of galactic satellite system is mainly originated by the hydrodynamical and radiative effects of hosts on satellites.       galaxies : general  galaxies : formation  galaxies : interactions  methods : observational
recently, it has been shown that the effective field theory of the ponzano - regge model with which spinless massive particles are coupled is given by three dimensional euclidean noncommutative scalar field theory in the lie algebraic noncommutative space @xmath0=2i\kappa \epsilon^{ijk}{\hat{x}}_k ~(i, j, k=1,2,3)$ ] with @xmath1, where @xmath2 is a gravitational constant.   we examine whether there exists the relation between spinless massive particles coupled with @xmath3 dimensional einstein gravity and the lorentzian version of the noncommutative field theory.   then, we point out that the momentum space of the spinless massive particles in 2 + 1 dimensional einstein gravity is generally different from that of the noncommutative field theory, which is given by @xmath4 group space.    yuya sasai and naoki sasakura     +
we revisit the globally coupled map lattice ( gcml ) and also propose a new extended globally coupled map lattice ( egcml ) with an inverse power law interaction. in gcml we clarify the mechanism of the basic posi - nega switch in the two - cluster regime.   we show that there is a natural mechanism in gcml which guarantees no mixing of maps across their mean field in the chaotic transient process. in the turbulent regime of gcml   there is a prominent period three window. in the correlator analysis   we also find a remnant of periodic motion of quasi - clusters with high rate mixing almost everywhere in the turbulent regime of the large - size gcml.   the so - called hidden coherence is the most modest remnant.   the egcml shares the same intriguing properties with gcml and exhibits an amazing spatial cluster formation during the chaotic transient process.   an analytic approach is proposed which relates the periodicity manifestation in the turbulent regime of gcml to the periodic window of a single logistic map.   +    # 1@xmath0#1
we present a scaling law that predicts the values of the stresses obtained in numerical simulations of saturated mri - driven turbulence in non - stratified shearing boxes.   it relates the turbulent stresses to the strength of the vertical magnetic field, the sound speed, the vertical size of the box, and the numerical resolution and predicts accurately the results of 35 numerical simulations performed for a wide variety of physical conditions.   we use our result to show that the saturated stresses in simulations with zero net magnetic flux depend linearly on the numerical resolution and would become negligible if the resolution were set equal to the natural dissipation scale in astrophysical disks.   we conclude that, in order for mri - driven turbulent angular momentum transport to be able to account for the large value of the effective alpha viscosity inferred observationally, the disk must be threaded by a significant vertical magnetic field and the turbulent magnetic energy must be in near equipartition with the thermal energy.   this result has important implications for the spectra of accretion disks and their stability.
data immersion has advantages in astrophysical visualization.   complex multi - dimensional data and phase spaces can be explored in a seamless and interactive viewing environment. putting the user in the data   is a first step toward immersive data analysis.   we present a technique for creating 360@xmath0 spherical panoramas with astrophysical data.   the three - dimensional software package blender and the google spatial media module are used together to immerse users in data exploration.   several examples employing these methods exhibit how the technique works using different types of astronomical data.   + * accepted for publication in the journal pasp special focus issue _ techniques and methods for astrophysical data visualization. _ *
we present here a method for the extraction of the differential phase of an atom gradiometer that exploits the correlation of the vibration signal measured by an auxiliary classical sensor, such as a seismometer or an accelerometer.   we show that sensitivities close to the quantum projection noise limit can be reached, even when the vibration noise induces phase fluctuations larger than @xmath0  . this method does nt require the correlation between the atomic and classical signals to be perfect and allows for an exact determination of the differential phase, with no bias.   it can also be applied to other configurations of differential interferometers, such as for instance gyrometers, conjugate interferometers for the measurement of the fine structure constant, or differential accelerometers for tests of the equivalence principle or detection of gravitational waves.
this letter reports on a new method of analysing experimentally gained time series with respect to different types of noise involved, namely, we show that it is possible to differentiate between dynamical and measurement noise.   this method does not depend on previous knowledge of model equations.   for the complicated case of a chaotic dynamics spoiled at the same time by dynamical and measurement noise, we even show how to extract from data the magnitude of both types of noise. as a further result  , we present a new criterion to verify the correct embedding for chaotic dynamics with dynamical noise.
we present results on the parity violation effects and global system polarization measurements in au+au collisions at @xmath0 = @xmath1 gev obtained with the star detector at rhic.   the parity violation effects are studied by three particle azimuthal correlations of charged particles.   the global polarization of the system is examined by measuring the polarization of strange hyperons with respect to the collision reaction plane.    _   key words _   relativistic heavy ion collisions, global polarization, parity violation.
the dynamics of polymer translocation through a pore has been the subject of recent theoretical and experimental works.   we have considered theoretical estimates and performed computer simulations to understand the mechanism of dna uptake into the cell nucleus, a phenomenon experimentally investigated by attaching a small bead to the free end of the double helix and pulling this bead with the help of an optical trap.   the experiments show that the uptake is monotonous and slows down when the remaining dna segment becomes very short.   numerical and analytical studies of the entropic repulsion between the dna filament and the membrane wall suggest a new interpretation of the experimental observations.   our results indicate that the repulsion monotonically decreases as the uptake progresses.   thus, the dna is pulled in ( i ) either by a small force of unknown origin, and then the slowing down can be interpreted only statistically ; ( ii ) or by a strong but slow ratchet mechanism, which would naturally explain the observed monotonicity, but then the slowing down requires additional explanations. only further experiments can unambiguously distinguish between these two mechanisms.
using the different versions of phenomenological proximity potential as well as other parametrizations within the proximity concept, we perform a detailed comparative study of fusion barriers for asymmetric colliding nuclei with asymmetry parameter as high as 0.23. in all, 12 different proximity potentials are robust against the experimental data of 60 reactions.   our detailed study reveals that the surface energy coefficient as well as radius of the colliding nuclei depend significantly on the asymmetry parameter.   all models are able to explain the fusion barrier heights within @xmath0 on the average.   the potentials due to bass 80, aw 95, and denisov dp explain nicely the fusion cross sections at above- as well as below - barrier energies.
scattering of a quantum particle from an oscillating barrier or well does not generally conserve the particle energy owing to energy exchange with the photon field, and an incoming particle - free state is scattered into a set of outgoing ( transmitted and reflected ) free states according to floquet scattering theory. here   we introduce two families of oscillating non - hermitian potential wells in which floquet scattering is fully suppressed for any energy of the incident particle.   the scattering - free oscillating potentials are synthesized by application of the darboux transformation to the time - dependent schrdinger equation.   for one of the two families of scattering - free potentials, the oscillating potential turns out to be fully invisible.
an isolated mixture of smooth, inelastic hard spheres supports a homogeneous cooling state with different kinetic temperatures for each species.   this phenomenon is explored here by molecular dynamics simulation of a two component fluid, with comparison to predictions of the enskog kinetic theory.   the ratio of kinetic temperatures is studied for two values of the restitution coefficient, @xmath0 and @xmath1, as a function of mass ratio, size ratio, composition, and density.   good agreement between theory and simulation is found for the lower densities and higher restitution coefficient ; significant disagreement is observed otherwise.   the phenomenon of different temperatures is also discussed for driven systems, as occurs in recent experiments.   differences between the freely cooling state and driven steady states are illustrated.
we present a detonating failed deflagration model of type ia supernovae. in this model,   the thermonuclear explosion of a massive white dwarf follows an off - center deflagration.   we conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center. in all cases   studied, we find that only a small amount of stellar fuel is consumed during deflagration phase, no explosion is obtained, and the released energy is mostly wasted on expanding the progenitor.   products of the failed deflagration quickly reach the stellar surface, polluting and strongly disturbing it.   these disturbances eventually evolve into small and isolated shock - dominated regions which are rich in fuel.   we consider these regions as seeds capable of forming self - sustained detonations that, ultimately, result in the thermonuclear supernova explosion.   preliminary nucleosynthesis results indicate the model supernova ejecta are typically composed of about @xmath0 of silicon group elements, @xmath1 of iron group elements, and are essentially carbon - free.   the ejecta have a composite morphology, are chemically stratified, and display a modest amount of intrinsic asymmetry.   the innermost layers are slightly egg - shaped with the axis ratio @xmath2 and dominated by the products of silicon burning.   this central region is surrounded by a shell of silicon - group elements.   the outermost layers of ejecta are highly inhomogeneous and contain products of incomplete oxygen burning with only small admixture of unburned stellar material.   the explosion energies are @xmath3  erg.
in this paper, we introduce a distributed dynamic routing algorithm for secondary users ( sus ) to minimize their interference with the primary users ( pus ) in multi - hop cognitive radio ( cr ) networks.   we use the medial axis with a relaxation factor as a reference path which is contingent on the states of the pus. along the axis, we construct a hierarchical structure for multiple sources to reach cognitive pilot channel ( cpc ) base stations. we use a temporal and spatial dynamic non - cooperative game to model the interactions among sus as well as their influences from pus in the multi - hop structure of the network.   a multi - stage fictitious play learning is used for distributed routing in multi - hop cr networks.   we obtain a set of mixed ( behavioral ) nash equilibrium strategies of the dynamic game in closed form by backward induction.   the proposed algorithm minimizes the overall interference and the average packet delay along the routing path from su nodes to cpc base stations in an optimal and distributed manner.
we present _ hst_/nicmos @xmath0 m, pa@xmath1 ( @xmath2 m ) and continuum images of the starburst galaxies m82 and ngc  253 at an unprecedented spatial resolution. in both galaxies we detect  compact sources superimposed on a diffuse background in the disk of the galaxies together with a component above and below the plane of the galaxy.   the radio and  emissions perpendicular to the disk of m82 show a remarkable similarity to each other, suggesting that both emissions originate in shocks from supernova explosions. we find a spatial correspondence between bright _ compact _  emitting regions and the location of radio supernova remnants ( snr ) for approximately @xmath3% of radio snrs in m82 and ngc  253.   this lack of a one - to - one correspondence, more than being indicative of a different origin for the radio and  emission in starbursts, suggests two populations of snrs : an older population ( @xmath4yr ) traced by the  emission and a younger population ( a few hundred years old ) traced by the radio snrs.   we therefore conclude that the  emission in starburst galaxies provides a good estimate of the supernova activity. using our newly determined    luminosities ( corrected for extinction ) of m82 and ngc  253, we reevaluate the calibration of the supernova rate in terms of the  luminosity for starburst galaxies.
we discuss the existence of huge thermal neutron capture cross sections in several nuclei.   the values of the cross sections are several orders of magnitude bigger than expected at these very low energies.   we lend support to the idea that this phenomenon is random in nature and is similar to what we have learned from the study of parity violation in the actinide region. the idea of statistical doorways is advanced as a unified concept in the delineation of large numbers in the nuclear world.   the average number of maxima per unit mass, @xmath0 in the capture cross section is calculated and related to the underlying cross section correlation function and found to be @xmath1, where @xmath2 is a characteristic mass correlation width which designates the degree of remnant coherence in the system.   we trace this coherence to nucleosynthesis which produced the nuclei whose neutron capture cross sections are considered here.
we report the results of a search for point - like deviations from isotropy in the arrival directions of ultra  high energy cosmic rays in the northern hemisphere. in the monocular data   set collected by the high  resolution fly s eye, consisting of 1,525 events with energy exceeding @xmath0 ev, we find no evidence for point - like excesses.   we place 90% c.l.   upper limits less than or equal to 0.8 cosmic rays / km@xmath1yr on the flux from such sources as a function of position in the sky.   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,   ,  ,     +    cosmic rays, anisotropy, point source, hires
damped ly@xmath0 systems seen in spectra of background quasars are generally thought to represent high redshift counterparts of present - day galaxies.   we summarize observations of heavy element abundances in damped ly@xmath0 systems.   the results of a systematic search for co and c  ii@xmath1 absorption in 17 damped ly@xmath0 systems are also presented using observations obtained with the 10 m keck telescopes.   the latter provides a useful constraint on the expected strength of  158@xmath2 m emission from damped ly@xmath0 galaxies.   it is hoped that these results will be useful for planning future radio to millimeter wave observations of high redshift galaxies using next generation instruments which are now being built.
i develop n - site cluster approximations for a stochastic sandpile in one dimension.   a height restriction is imposed to limit the number of states : each site can harbor at most two particles ( height @xmath0 ).   ( this yields a considerable simplification over the unrestricted case, in which the number of states per site is unbounded. ) on the basis of results for @xmath1 sites, i estimate the critical particle density as @xmath2, in good agreement with simulations.   a coherent anomaly analysis yields estimates for the order parameter exponent [ @xmath3 and the relaxation time exponent ( @xmath4 ).
current approaches for building quantum computing devices focus on two - level quantum systems which nicely mimic the concept of a classical bit, albeit enhanced with additional quantum properties.   however, rather than artificially limiting the number of states to two, the use of @xmath0-level quantum systems ( qudits ) could provide advantages for quantum information processing. among other merits  , it has recently been shown that multi - level quantum systems can offer increased stability to external disturbances  a key problem in current technologies. in this study   we demonstrate that topological quantum memories built from qudits, also known as abelian quantum double models, exhibit a substantially increased resilience to noise.   that is, even when taking into account the multitude of errors possible for multi - level quantum systems, topological quantum error correction codes employing qudits can sustain a larger error rate than their two - level counterparts.   in particular, we find strong numerical evidence that the thresholds of these error - correction codes are given by the hashing bound.   considering the significantly increased error thresholds attained, this might well outweigh the added complexity of engineering and controlling higher dimensional quantum systems.
we study the influence of disorder and randomly distributed impurities on the properties of correlated antiferromagnets. to this end the hubbard model with ( i ) random potentials, ( ii ) random hopping elements, and ( iii ) randomly distributed values of interaction is treated using quantum monte carlo and dynamical mean - field theory. in cases ( i ) and ( iii ) weak disorder can lead to an enhancement of antiferromagnetic ( af ) order : in case ( i ) by a disorder - induced delocalization, in case ( iii ) by binding of free carriers at the impurities. for strong disorder or large impurity concentration antiferromagnetism is eventually destroyed.   random hopping leaves the local moment stable but af order is suppressed by local singlet formation.   random potentials induce impurity states within the charge gap until it eventually closes.   impurities with weak interaction values shift the hubbard gap to a density off half - filling. in both cases   an antiferromagnetic phase without charge gap is observed.
the states of an open quantum system are coupled via the environment of scattering wavefunctions.   the complex coupling coefficients @xmath0 between system and environment arise from the principal value integral and the residuum. at high level density where the resonance states overlap,   the dynamics of the system is determined by exceptional points. at these points,   the eigenvalues of two states are equal and the corresponding eigenfunctions are linearly dependent. it is shown in the present paper that im@xmath1 and re@xmath1 influence the system properties differently in the surrounding of exceptional points. controlling the system by a parameter  , the eigenvalues avoid crossing in energy near an exceptional point under the influence of re@xmath1 in a similar manner as it is well known from discrete states.   im@xmath1 however leads to width bifurcation and finally ( when the system is coupled to one channel, i.e. to a common continuum of scattering wavefunctions ), to a splitting of the system into two parts with different characteristic time scales.   physically, the system is stabilized by this splitting since the lifetimes of most ( @xmath2 ) states are longer than before while that of only one state is shorter. in the cross section   the short - lived state appears as a background term in high - resolution experiments.   the wavefunctions of the long - lived states are mixed in those of the original ones in a comparably large parameter range.   numerical results for the eigenvalues and eigenfunctions are shown for @xmath3 and 10 states coupled mostly to 1 channel.
we present hi spectral - line imaging of the extremely metal - poor galaxy ddo68.   this system has a nebular oxygen abundance of only @xmath03% z@xmath1, making it one of the most metal - deficient galaxies known in the local volume.   surprisingly, ddo68 is a relatively massive and luminous galaxy for its metal content, making it a significant outlier in the mass - metallicity and luminosity - metallicity relationships.   the origin of such a low oxygen abundance in ddo68 presents a challenge for models of the chemical evolution of galaxies.   one possible solution to this problem is the infall of pristine neutral gas, potentially initiated during a gravitational interaction. using archival hi spectral - line imaging obtained with   the karl g. jansky very large array, we have discovered a previously unknown companion of ddo 68.   this low - mass ( m@xmath2 @xmath3 2.8@xmath410@xmath5 m@xmath1 ), recently star - forming ( sfr@xmath6 @xmath3 1.4@xmath410@xmath7 m@xmath1yr@xmath8,   sfr@xmath9 @xmath10 7@xmath410@xmath11 m@xmath1yr@xmath8 ) companion has the same systemic velocity as ddo 68 ( v@xmath12 @xmath3 506 kms@xmath8 ; d @xmath3 12.74@xmath130.27 mpc ) and is located at a projected distance of @xmath042 kpc.   new hi maps obtained with the 100 m robert c. byrd green bank telescope provide evidence that ddo 68 and this companion are gravitationally interacting at the present time.   low surface brightness hi gas forms a bridge between these
the metrization of the space of neural responses is an ongoing research program seeking to find natural ways to describe, in geometrical terms, the sets of possible activities in the brain.   one component of this program are the _ spike metrics _, notions of distance between two spike trains recorded from a neuron.   alignment spike metrics work by identifying `` equivalent '' spikes in one train and the other.   we present an alignment spike metric having @xmath0 underlying geometrical structure ; the @xmath1 version is euclidean and is suitable for further embedding in euclidean spaces by multidimensional scaling methods or related procedures.   we show how to implement a fast algorithm for the computation of this metric based on bipartite graph matching theory.   @xmath2center for studies in physics and biology, rockefeller university, new york ny    @xmath3harvard faculty of arts and sciences, cambridge ma
compact groups of galaxies have posed a number of challenging questions.   intensive observational and theoretical studies are now providing answers to many of these, and at the same time, are revealing unexpected new clues about the nature and role of these systems.   most compact groups contain a high fraction of galaxies having morphological or kinematical peculiarities, nuclear radio and infrared emission, and starburst or active galactic nuclei ( agn ) activity.   they contain large quantities of diffuse gas and are dynamically dominated by dark matter.   they most likely form as subsystems within looser associations and evolve by gravitational processes.   strong galaxy interactions result and merging is expected to lead to the ultimate demise of the group.   compact groups are surprisingly numerous, and may play a significant role in galaxy evolution.   psfig.sty  @xmath0
we study the occurrence of modulational instabilities in lattices with non - local, power - law hoppings and interactions.   choosing as a case study the discrete nonlinear schrdinger equation, we consider one - dimensional chains with power - law decaying interactions ( with exponent @xmath0 ) and hoppings ( with exponent @xmath1 ) : an extensive energy is obtained for @xmath2.   we show that the effect of power - law interactions is that of shifting the onset of the modulational instabilities region for @xmath3. at a critical value of the interaction strength, the modulational stable region shrinks to zero.   similar results are found for effectively short - range nonlocal hoppings ( @xmath4 ) : at variance, for longer - ranged hoppings ( @xmath5 ) there is no longer any modulational stability.   the hopping instability arises for @xmath6 perturbations, thus the system is most sensitive to the perturbations of the order of the system s size.   we also discuss the stability regions in the presence of the interplay between competing interactions - ( e.g., attractive local and repulsive nonlocal interactions ).   we find that noncompeting nonlocal interactions give rise to a modulational instability emerging for a perturbing wave vector @xmath7 while competing nonlocal interactions may induce a modulational instability for a perturbing wave vector @xmath8.   since for @xmath9 and @xmath4 the effects are similar to the effect produced on the stability phase diagram by finite range interactions and/or hoppings, we conclude that the modulational instability is `` genuinely '' long - ranged for @xmath10 nonlocal hoppings.
we use mller s energy - momentum complex in order to explicitly compute the energy and momentum density distributions for an exact solution of einstein s field equations with a negative cosmological constant minimally coupled to a static massless scalar field in a static, spherically symmetric background in @xmath0-dimensions.   +   + _ @xmath1 physics department, `` gh.   asachi '' technical university, + 6600 iasi, romania + @xmath2 department of mechanical & industrial engineering, university of thessaly, + 383 34 volos, greece + _    _ keywords _ : energy - momentum complex, scalar field +   + pacs numbers : 04.20.-q, 04.20.jb
our previous calculation of the spin  dependent structure function @xmath0 is revisited.   the interest in this structure function is to a great extent motivated by the fact that it receives contributions from twist  two as well as from twist  three operators already in leading order of @xmath1 thus offering the unique possibility of directly assessing higher  twist effects. in our former calculation   the lattice operators were renormalized perturbatively and mixing with lower  dimensional operators was ignored. however, the twist   three operator which gives rise to the matrix element @xmath2 mixes non  perturbatively with an operator of lower dimension. taking this effect into account leads to a considerably smaller value of @xmath2, which is consistent with the experimental data.
we consider an idealized situation where the quark - gluon plasma ( qgp ) is described by a perfect, 3 + 1 dimensional fluid dynamic model starting from an initial state and expanding until a final state where freeze - out and/or hadronization takes place.   we study the entropy production with attention to effects of ( i ) numerical viscosity, ( ii ) late stages of flow where the bag constant and the partonic pressure are becoming similar, ( iii ) and the consequences of final freeze - out and constituent quark matter formation.
the question of universality class of pair contact process with diffusion ( pcpd ) is revisited with an alternative approach.   we study persistence in generalized pair - contact process with diffusion ( gpcpd ) introduced by noh and park, ( phys.   rev.   e 69,016122(2004 ) ).   this model allows us to interpolate between directed percolation ( dp ) and pcpd universality classes.   we find that transition to nonzero persistence is at same parameter value as transition to zero number density.   we obtain finite size scaling and off - critical scaling collapse for persistence and find critical exponents by fitting phenomenological scaling laws to persistence. while the dynamic scaling exponent @xmath0 varies continuously in gpcpd, the correlation - time exponent @xmath1 matches with directed percolation universality class.   february 2014    _ keywords _ : persistence, non - equilibrium phase transition, pair contact processes
the 3rd egret catalog of high - energy gamma - ray sources contains 170 unidentified sources, and there is great interest in the nature of these sources.   one means of determining source class is the study of flux variability on time scales of days ; pulsars are believed to be stable on these time scales while blazars are known to be highly variable.   in addition, previous work has demonstrated that 3eg j0241 - 6103 and 3eg j1837 - 0606 are candidates for a new gamma - ray source class.   these sources near the galactic plane display transient behavior but can not be associated with any known blazars.   although many instances of flaring agn have been reported, the egret database has not been systematically searched for occurrences of short - timescale ( @xmath0 day ) variability.   these considerations have led us to conduct a systematic search for short - term variability in egret data, covering all viewing periods through proposal cycle 4.   six 3eg catalog sources are reported here to display variability on short time scales ; four of them are unidentified. in addition  , three non - catalog variable sources are discussed.
we revisit the status of lepton flavor violating ( lfv ) @xmath0 contact interactions from the view point of -conversion in nuclei.   we consider their contribution to this lfv process via the two mechanisms on the hadronic level : direct nucleon and meson exchange ones. in the former case   the quarks are embedded directly into the nucleons while in the latter in mesons which then interact with nucleons in a nucleus.   we revise and in some cases reevaluate the hadronic parameters relevant for both mechanisms and calculate the contribution of the above mentioned contact interactions in coherent -conversion in various nuclei.   then we update our previous upper bounds and derive new ones for the scales of the @xmath0 contact interactions from the experimental limits on the capture rates of -conversion.   we compare these limits with the ones derived in the literature from other lfv processes and comment on the prospects of lhc searches related to the contact @xmath0 interactions.
we discuss the neutrino constraints from solar and terrestrial dark matter ( dm ) annihilations in the inelastic dark matter ( idm ) scenario after the recent cdms ii results. to reconcile the dama / libra data with constraints from all other direct experiments, the idm needs to be light ( @xmath0 gev ) and have a large dm - nucleon cross section ( @xmath1 10@xmath2 pb in the spin - independent ( si ) scattering and @xmath1 10 pb in the spin - dependent ( sd ) scattering ). the dominant contribution to the idm capture in the sun   is from scattering off fe / al in the si / sd case.   current bounds from super - kamiokande exclude the hard dm annihilation channels, such as @xmath3, @xmath4, @xmath5 and @xmath6. for soft channels such as @xmath7 and @xmath8,   the limits are loose, but could be tested or further constrained by future icecube plus deepcore. for neutrino constraints from the dm annihilation in the earth, due to the weaker gravitational effect of the earth and inelastic capture condition, the constraint exists only for small mass splitting @xmath9 40 kev and @xmath10 gev even in the @xmath6 channel.
synthetic spectra generated with the parameterized supernova synthetic   spectrum code synow are compared to photospheric   phase spectra of type  ib supernovae ( sne  ib ).   although the synthetic spectra are based on many simplifying approximations, including spherical symmetry, they account well for the observed spectra.   our sample of sne  ib obeys a tight relation between the velocity at the photosphere, as determined from the fe ii features, and the time relative to that of maximum light. from this   we infer that the masses and the kinetic energies of the events in this sample were similar. after maximum light   the minimum velocity at which the he  i features form usually is higher than the velocity at the photosphere, but the minimum velocity of the ejected helium is at least as low as 7000 .   previously unpublished spectra of sn  2000h reveal the presence of hydrogen absorption features, and we conclude that hydrogen lines also were present in sne  1999di and 1954a.   hydrogen appears to be present in sne  ib in general, although in most events it becomes too weak to identify soon after maximum light.   the hydrogen  line optical depths that we use to fit the spectra of sne  2000h, 1999di, and 1954a are not high, so only a mild reduction in the hydrogen optical depths would be required to make these events look like typical sne  ib.   similarly, the he  i line optical depths are not very high, so a moderate reduction would make sne  ib look like sne  ic.
we present several estimates of the rate of simultaneous detection of the merging of a binary system of neutron stars in the electromagnetic and the gravitational wave domains, assuming that they produce short gamma - ay bursts ( grbs ).   we have based our estimations on a carefully selected sample of short grbs corrected from redshift effects.   the results presented in this paper are based on actual observation only. in the electromagnetic spectrum,   we considered observations by current ( _ swift _ and _ fermi _ ) and future ( _ loft _ and _ svom _ ) missions. in the gravitational wave domain  , we consider detections by the advanced virgo instrument alone and the network of both advanced ligo and advanced virgo.   we discuss on the possible biases present in our sample, and how to fix them. for present missions, assuming a detection in the following years, we find that we should observe simultaneously between 0.11 and 0.63 gravitational wave events per year with _   swift _ and _ fermi _, respectively. for future projects ( _ loft   _ and _ svom _ ), we can expect less than one common detection per year.   we check the consistency of our results with several previously published rate of detection of gravitational waves.       gravitational waves   gamma - ray burst : general  stars : neutron.
we have recently presented the complete @xmath0 corrections to the semileptonic decay width of the @xmath1 quark at maximal recoil. here   we discuss various technical aspects of that calculation and further applications of similar methods.   in particular, we describe an expansion which facilitates the phase space integrations and the treatment of the mixed real  virtual corrections, for which taylor expansion does not work and the so - called eikonal expansion must be employed.   several terms of the expansion are given for the @xmath0 qcd corrections to the differential semileptonic decay width of the @xmath1quark at maximal recoil.   we also demonstrate how the light quark loop corrections to the top quark decay rate can be obtained using the same methods.   we briefly discuss the application of these techniques to the calculation of the @xmath0 correction to zero recoil sum rules for heavy flavor transitions.
a new kind of tripartite coherent - entangled state ( ces ) @xmath0 is proposed, which exhibits the properties of both coherence and entanglement.   we investigate its completeness and orthogonality, and find it can make up a representation of tripartite ces.   a protocol for generating the tripartite ces is proposed using asymmetric beam splitter.   applications of the tripartite ces in quantum optics are also presented.   _ keywords _ : new tripartite coherent - entangled state, asymmetry beam - splitter, squeezing operator, wigner operator
we revisit the kinematical data for 204 globular clusters in the halo of m87. beyond 3 r@xmath0 along the major axis of the galaxy light,   these globular clusters exhibit substantial rotation ( @xmath1 km s@xmath2 ) that translates into an equally substantial spin ( @xmath3 ).   the present appearance of m87 is most likely the product of a single major merger, since this event is best able to account for so sizable a spin.   a rotation this large makes improbable any significant accretion of material after this merger, since that would have diluted the rotation signature.   we see weak evidence for a difference between the kinematics of the metal  poor and metal  rich population, in the sense that the metal  poor globular clusters appear to dominate the rotation. if, as we suspect, the last major merger event of m87 was mainly dissipationless and did not trigger the formation of a large number of globular clusters, the kinematic difference between the two could reflect their orbital properties in the progenitor galaxies ; these differences would be compatible with these progenitors having formed in dissipational mergers.   however, to put strong kinematic constraints on the origin of the globular clusters themselves is difficult, given the complex history of the galaxy and its last dominant merger event.
the structural and elastic properties as well as phonon - dispersion relations of the heusler - type alloys fe@xmath0val and fe@xmath0vga are computed using density - functional and density - functional perturbation theory within the generalized - gradient approximation.   the calculated equilibrium lattice constants agree well with the experimental values.   the elastic constants of fe@xmath0val and fe@xmath0vga are predicted for the first time. from the elastic constants the shear modulus, young s modulus, poisson s ratio, sound velocities and debye temperatures   are obtained. by analyzing the ratio between the bulk and shear modulii,   we conclude that both fe@xmath0val and fe@xmath0vga are brittle in nature.   the computed phonon - dispersion relation shows that both compounds are dynamically stable in the l1@xmath0 structure without any imaginary phonon frequencies.   the isomer shifts of fe in the two compounds are discussed in terms of the fe s partial density of states, which reveal larger ionicity / less hybridization in fe@xmath0vga than in fe@xmath0val.   for the same reason the cauchy pressure is negative in fe@xmath0val but positive in fe@xmath0vga.
we discuss the construction of multi - caloron solutions with non - trivial holonomy, both as approximate superpositions and exact self - dual solutions.   the charge @xmath0 @xmath1 moduli space can be described by @xmath2 constituent monopoles.   exact solutions help us to understand how these constituents can be seen as independent objects, which seems not possible with the approximate superposition.   an  impurity scattering " calculation provides relatively simple expressions.   like at zero temperature an explicit parametrization requires solving a quadratic adhm constraint, achieved here for a class of axially symmetric solutions.   we will discuss the properties of these exact solutions in detail, but also demonstrate that interesting results can be obtained without explicitly solving for the constraint.
we present a revised measurement of the mass of the central black hole ( @xmath0 ) in the seyfert  1 galaxy ngc  4151.   the new stellar dynamical mass measurement is derived by applying an axisymmetric orbit - superposition code to near - infrared integral field data obtained using adaptive optics with the gemini nifs spectrograph.   when our models attempt to fit both the nifs kinematics and additional low spatial resolution kinematics, our results depend sensitively on how @xmath1 is computed  probably a consequence of complex bar kinematics that manifest immediately outside the nuclear region.   the most robust results are obtained when only the high spatial resolution kinematic constraints in the nuclear region are included in the fit.   our best estimates for the bh mass and @xmath2-band mass - to - light ratio are @xmath3 ( 1@xmath4 error ) and @xmath5 ( 3@xmath4 error ), respectively ( the quoted errors reflect the model uncertainties ).   our bh mass measurement is consistent with estimates from both reverberation mapping ( @xmath6 ) and gas kinematics ( @xmath7 ; 1@xmath4 errors ), and our best - fit mass - to - light ratio is consistent with the photometric estimate of @xmath8.   the nifs kinematics give a central bulge velocity dispersion @xmath9 , bringing this object slightly closer to the relation for quiescent galaxies.   although ngc  4151 is one of only a few seyfert  1 galaxies in which it is possible to obtain a direct dynamical bh mass measurement  and thus, an independent calibration of the reverberation mapping mass scale  the complex bar kinematics makes it less than ideally suited for this purpose.
exact formula for the force between two identical static point charges coupled to the nonlinear scalar field of two - dimensional signum - gordon model is obtained.   pertinent solution of the field equation is found in the form of one dimensional integral.   the force exactly vanishes when the distance between charges exceeds certain critical value.   pacs : 11.27.+d, 11.10.lm, 03.50.kk +
corrugation instabilities occurring for solutions of the riemann problem in relativistic hydrodynamics in which the fluid moves with a non - zero velocity tangent to the initial discontinuity are studied numerically.   we perform simulations both for ultrarelativistic and perfect gas equations of state.   we focus on a set of problems with moderately relativistic velocities but exhausting all possible wave patterns of solutions.   perturbations are applied to the shape of the initial discontinuity.   instabilities that develop are only restricted to a region around a contact discontinuity.   both shock and rarefaction waves appear to be stable.
the @xmath0-matrix theory formulation of closed - orbit theory recently proposed by granger and greene is extended to atoms in crossed electric and magnetic fields.   we then present a semiclassical quantization of the hydrogen atom in crossed fields, which succeeds in resolving individual lines in the spectrum, but is restricted to the strongest lines of each @xmath1-manifold. by means of a detailed semiclassical analysis of the quantum spectrum,   we demonstrate that it is the abundance of bifurcations of closed orbits that precludes the resolution of finer details.   they necessitate the inclusion of uniform semiclassical approximations into the quantization process.   uniform approximations for the generic types of closed - orbit bifurcation are derived, and a general method for including them in a high - resolution semiclassical quantization is devised.
a method is presented for the optimization of one - body and inhomogeneous two - body terms in correlated electronic wave functions of jastrow - slater type.   the most general form of inhomogeneous correlation term which is compatible with crystal symmetry is used and the energy is minimized with respect to all parameters using a rapidly convergent iterative approach, based on monte carlo sampling of the energy and fitting of energy fluctuations.   the energy minimization is performed exactly within statistical sampling error for the energy derivatives and the resulting one- and two - body terms of the wave function are found to be well - determined.   the largest calculations performed require the optimization of over 3000 parameters.   the inhomogeneous two - electron correlation terms are calculated for diamond and rhombohedral graphite.   the optimal terms in diamond are found to be approximately homogeneous and isotropic over all ranges of electron separation, but exhibit some inhomogeneity at short- and intermediate - range, whereas those in graphite are found to be homogeneous at short - range, but inhomogeneous and anisotropic at intermediate- and long - range electron separation.
a formalism is developed which describes the extent to which stochastic oscillations in biochemical models are synchronised.   it is based on the calculation of the complex coherence function within the linear noise approximation.   the method is illustrated on a simple example and then applied to study the synchronisation of chemical concentrations in social amoeba.   the degree to which variation of rate constants in different cells and the volume of the cells affects synchronisation of the oscillations is explored, and the phase lag calculated. in all cases the analytical results are shown to be in good agreement with those obtained through numerical simulations.
given a single copy of a mixed state of the form @xmath0 what is the optimal measurement to estimate the parameter @xmath1, if @xmath2 and @xmath3 are known?   we present a general strategy to obtain the optimal measurements employing a bayesian estimator.   the measurements are chosen to minimize the deviation between the estimated- and the true value of @xmath1.   we explicitly determine the optimal measurements for a general two - dimensional system and for important higher dimensional cases.
the population of compact massive galaxies observed at @xmath0 are hypothesised, both observationally and in simulations, to be merger remnants of gas - rich disc galaxies. to probe such a scenario we analyse a sample of 12 gas - rich and active star forming sub - mm galaxies ( smgs ) at @xmath1.   we present a structural and size measurement analysis for all of these objects using very deep acs and nicmos imaging in the goods - north field.   our analysis reveals a heterogeneous mix of morphologies and sizes.   we find that four galaxies ( 33%@xmath217% ) show clear signs of mergers or interactions, which we classify as early - stage mergers.   the remaining galaxies are divided into two categories : five of them ( 42%@xmath218% ) are diffuse and regular disc - like objects, while three ( 25%@xmath214% ) are very compact, spheroidal systems.   we argue that these three categories can be accommodated into an evolutionary sequence, showing the transformation from isolated, gas - rich discs with typical sizes of 2 - 3 kpc, into compact ( @xmath3 1 kpc ) galaxies through violent major merger events, compatible with the scenario depicted by theoretical models.   our findings that some smgs are already dense and compact provides strong support to the idea that smgs are the precursors of the compact, massive galaxies found at slightly lower redshift.   +        galaxies : evolution  galaxies : high - redshift  submillimetre  galaxies : starburst  galaxies : active
observations at radio wavelengths address key problems in astrophysics, astrobiology, and lunar structure including the first light in the universe ( the epoch of reionization ), the presence of magnetic fields around extrasolar planets, particle acceleration mechanisms, and the structure of the lunar ionosphere.   moreover, achieving the performance needed to address these scientific questions demands observations at wavelengths longer than those that penetrate the earth s ionosphere, observations in extremely `` radio quiet '' locations such as the moon s far side, or both.   we describe a series of lunar - based radio wavelength interferometers of increasing capability.   the radio observatory for lunar sortie science ( rolss ) is an array designed to be deployed during the first lunar sorties ( or even before via robotic rovers ) and addressing particle acceleration and the lunar ionosphere.   future arrays would be larger, more capable, and deployed as experience is gained in working on the lunar surface.
we theoretically investigate the quantum statistical properties of light transmitted through an atomic medium with strong optical non - linearity induced by rydberg - rydberg van der waals interactions. in our setup, atoms are located in a cavity and non - resonantly driven on a two - photon transition from their ground state to a rydberg level via an intermediate state by the combination of the weak signal field and a strong control beam. to characterize the transmitted light we compute the second - order correlation function @xmath0.   the simulations we obtained on the specific case of rubidium atoms suggest that the bunched or antibunched nature of the outgoing beam can be chosen at will by appropriately tuning the physical parameters.
we construct the first `` face - on '' tully - fisher ( tf ) relation for 24 galaxies with inclinations between 16@xmath0 and 41@xmath0.   the enabling measurements are integral - field, echelle spectroscopy from the wiyn 3.5 m telescope, which yield accurate kinematic estimates of disk inclination to @xmath1.   kinematic inclinations are of sufficient accuracy that our measured tf scatter of 0.42 mag is comparable to other surveys even without internal - absorption corrections.   three of four galaxies with significant kinematic and photometric asymmetries also have the largest deviations from our tf relation, suggesting that asymmetries make an important contribution to tf scatter. by measuring inclinations below 40@xmath0  , we establish a direct path to linking this scatter to the unprojected structure of disks and making non - degenerate dynamical mass - decompositions of spiral galaxies.
deep submillimetre surveys have successfully detected distant, star - forming galaxies, enshrouded in vast quantities of dust and which emit most of their energy at far infrared wavelengths.   these luminous galaxies are an important constituent of the universal star - formation history, and any complete model of galaxy evolution must account for their existence.   although these sources have been tentatively identified with very faint and sometimes very red optical counterparts, their poorly constrained redshift distribution has made their interpretation unclear.   in particular, it was not understood if these galaxies had been missed in previous surveys, or if they constituted a truly new class of objects, undetectable at other wavelengths.   by utilizing a radio selection technique, we have isolated a sample of 20 sub - mm objects representative of the 850@xmath0 m  population brighter than 5mjy with @xmath13.   we show that these galaxies are so heavily dust obscured that they remain essentially invisible to ultraviolet selection.   furthermore, relying on the radio - submillimeter flux density ratio, we estimate their redshift distribution, finding a median of two.   these results are inconsistent with the existence of a very high redshift ( @xmath2 ) population of primeval galaxies ( l@xmath3h@xmath4 ) contributing substantially to the sub - mm counts. while not a substitute for the thorough followup of blank field sub - mm surveys, our results do shed light on a substantial portion of the luminous sub - mm population with @xmath13.   # 1  * # 1 * @xmath5 @xmath6
we have imaged two normal, non - coronal, infrared - bright k giants, @xmath0  tau and @xmath0  boo, in the 1.4-mm and 2.8-mm continuum using bima.   these stars have been used as important absolute calibrators for several infrared ( ir ) satellites.   our goals are : ( 1 )  to establish whether these stars radiate as simple photospheres or possess long - wavelength chromospheres ; and ( 2 )  to make a connection between millimeter - wave and far - infrared ( fir ) absolute flux calibrations. to accomplish these goals we also present iso long wavelength spectrometer ( lws ) measurements of both these k giants.   the fir and millimeter continuum radiation is produced in the vicinity of the temperature minimum in @xmath0  tau and @xmath0  boo.   we find that current photospheric models predict fluxes in reasonable agreement with those observed for wavelengths which sample the upper photosphere, namely @xmath1125  @xmath2 m in @xmath0  tau and @xmath0  boo.   we clearly detect chromospheric radiation from both stars by 2.8  mm ( by 1.4  mm in the case of @xmath0  boo ).   only additional observations can determine precisely where beyond 125  @xmath2 m the purely radiative models fail.   until then, purely radiative models for these stars can only be used with confidence for calibration purposes below 125  @xmath2 m.
over the next decade, cosmological measurements of the large - scale structure of the universe will be sensitive to the combined effects of dynamical dark energy and massive neutrinos.   the matter power spectrum is a key repository of this information.   we extend higher - order perturbative methods for computing the power spectrum to investigate these effects over quasi - linear scales. through comparison with n - body simulations we establish the regime of validity of a time - renormalization group ( time - rg ) perturbative treatment that includes dynamical dark energy and massive neutrinos.   we also quantify the accuracy of standard ( spt ), renormalized ( rpt ) and lagrangian resummation ( lpt ) perturbation theories without massive neutrinos.   we find that an approximation that neglects neutrino clustering as a source for nonlinear matter clustering predicts the baryon acoustic oscillation ( bao ) peak position to @xmath0 accuracy for redshifts @xmath1, justifying the use of lpt for bao reconstruction in upcoming surveys.   we release a modified version of the public code which includes the additional physics discussed in the paper.
we give examples of rank one compact surfaces on which there exist recurrent geodesics that can not be shadowed by periodic geodesics.   we build rank one compact surfaces such that ergodic measures on the unit tangent bundle of the surface are not dense in the set of probability measures invariant by the geodesic flow. finally, we give examples of complete rank one surfaces for which the non wandering set of the geodesic flow is connected, the periodic orbits are dense in that set, yet the geodesic flow is not transitive in restriction to its non wandering set  .    _ universit de bretagne occidentale, 6 av.   le gorgeu, 29238 brest cedex, france _   _ lamfa, universit picardie jules verne, 33 rue st leu, 80000 amiens, france _
we investigate the quark - gluon three - point correlation function within a one - loop computation performed in the curci - ferrari massive extension of the faddeev - popov gauge - fixed action.   the mass term is used as a minimal way for taking into account the influence of the gribov ambiguity. our results, with renormalization - group improvement,   are compared with lattice data.   we show that the comparison is in general very satisfactory for the functions which are compatible with chiral symmetry, except for one.   we argue that this may be due to large systematic errors when extracting this function from lattice simulations.   the quantities which break chiral symmetry are more sensitive to the details of the renormalization scheme.   we however manage to reproduce some of them with good precision.   the chosen parameters allow to simultaneously fit the quark mass function coming from the quark propagator with a reasonably agreement.
we study the quantum - jump - based feedback control on the entanglement shared between two qubits with one of them subject to decoherence, while the other qubit is under the control.   this situation is very relevant to a quantum system consisting of nuclear and electron spins in solid states.   the possibility to prolong the coherence time of the dissipative qubit is also explored.   numerical simulations show that the quantum - jump - based feedback control can improve the entanglement between the qubits and prolong the coherence time for the qubit subject directly to decoherence.
azimuthal age / color gradients across spiral arms are a signature of long - lived spirals. from a sample of 19 normal ( or   weakly barred ) spirals where we have previously found azimuthal age / color gradient candidates, 13 objects were further selected if a two - armed grand - design pattern survived in a surface density stellar mass map.   mass maps were obtained from optical and near - infrared imaging, by comparing with a monte carlo library of stellar population synthesis models that allowed us to obtain the mass - to - light ratio in the @xmath0-band, @xmath1, as a function of ( @xmath2 ) versus  ( @xmath3 ) color.   the selected spirals were analyzed with fourier methods in search for other signatures of long - lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two - armed spiral in different wavebands, as expected from theory.   the results show additional signatures of long - lived spirals in at least 50% of the objects.
we have discovered an x - ray source, sax  j0635 + 0533, with a hard spectrum within the error box of the gev gamma - ray source in monoceros, 2eg  j0635 + 0521.   the unabsorbed flux from the source is @xmath0 in the 2 - 10  kev band.   the x - ray spectrum is consistent with a simple powerlaw model with absorption.   the photon index is @xmath1 and we detect emission out to 40  kev.   optical observations identify a counterpart with a v - magnitude of 12.8.   the counterpart has broad emission lines and the colors of an early b type star.   if the identification of the x - ray / optical source with the gamma - ray source is correct, then the source would be a gamma - ray emitting x - ray binary.   # 1
based on grad - shafranov - like equations, a gyrotropic plasma where the pressures in the static regime are only functions of the amplitude of the local magnetic field is shown to be amenable to a variational principle with a free energy density given by the parallel tension.   this approach is used to demonstrate that small- amplitude static holes constructed slightly below the mirror instability threshold identify with lump solitons of kpii equation and turn out to be unstable.   it is also shown that regularizing effects such as finite larmor radius corrections can not be ignored in the description of large - amplitude mirror structures.
feature selection plays a pivotal role in learning, particularly in areas were parsimonious features can provide insight into the underlying process, such as biology.   recent approaches for non - linear feature selection employing greedy optimisation of centred kernel target alignment(kta ), while exhibiting strong results in terms of generalisation accuracy and sparsity, can become computationally prohibitive for high - dimensional datasets.   we propose randsel, a randomised feature selection algorithm, with attractive scaling properties.   our theoretical analysis of randsel provides strong probabilistic guarantees for the correct identification of relevant features.   experimental results on real and artificial data, show that the method successfully identifies effective features, performing better than a number of competitive approaches.   ....   feature selection, kernels....
one dimensional systems sometimes show pathologically slow decay of currents.   this robustness can be traced to the fact that an _ integrable _ model is nearby in parameter space. in integrable models   some part of the current can be conserved, explaining this slow decay.   unfortunately, although this conservation law is formally anticipated, in practice it has been difficult to find in concrete cases, such as the heisenberg model.   we investigate this issue both analytically and numerically and find that the appropriate conservation law can be a _   non - analytic _ combination of the known local conservation laws and hence is invisible to elementary assumptions.
in this manuscript we introduced the generalized fractional riemann - liouville and caputo like derivative for functions defined on fractal sets.   the gamma, mittag - leffler and beta functions were defined on the fractal sets. the non - local laplace transformation is given and applied for solving linear and non - linear fractal equations.   the advantage of using these new nonlocal derivatives on fractals subset of real - line lies in the fact that they are used for better modelling of processes with memory effect.   * keyword : * fractal calculus ; triadic cantor set ; non - local laplace transformation ; memory processes ; generalized mittag - leffler function ; generalized gamma function ; generalized beta function
we consider linear arrays of cells of volume @xmath0 populated by monodisperse rods of size @xmath1, @xmath2, subject to hardcore exclusion interaction.   each rod experiences a position - dependent external potential. in one application   we also examine effects of contact forces between rods. we employ two distinct methods of exact analysis with complementary strengths and different limits of spatial resolution to calculate profiles of pressure and density on mesoscopic and microscopic length scales at thermal equilibrium.   one method uses density functionals and the other statistically interacting vacancy particles.   the applications worked out include gravity, power - law traps, and hard walls.   we identify oscillations in the profiles on a microscopic length scale and show how they are systematically averaged out on a well - defined mesoscopic length scale to establish full consistency between the two approaches.   the continuum limit, realized as @xmath3, @xmath4 at nonzero and finite @xmath1, connects our highest - resolution results with known exact results for monodisperse rods in a continuum.   we also compare the pressure profiles obtained from density functionals with the average microscopic pressure profiles derived from the pair distribution function.
spatial interaction between two or more classes or species has important implications in various fields and causes multivariate patterns such as segregation or association.   segregation occurs when members of a class or species are more likely to be found near members of the same class or conspecifics ; while association occurs when members of a class or species are more likely to be found near members of another class or species.   the null patterns considered are random labeling ( rl ) and complete spatial randomness ( csr ) of points from two or more classes, which is called _ csr independence _, henceforth.   the clustering tests based on nearest neighbor contingency tables ( nncts ) that are in use in literature are two - sided tests. in this article  , we consider the directional ( i.e., one - sided ) versions of the cell - specific nnct - tests and introduce new directional nnct - tests for the two - class case.   we analyze the distributional properties ; compare the empirical significant levels and empirical power estimates of the tests using extensive monte carlo simulations.   we demonstrate that the new directional tests have comparable performance with the currently available nnct - tests in terms of empirical size and power.   we use four example data sets for illustrative purposes and provide guidelines for using these nnct - tests.   _ keywords : _ association ; clustering ; complete spatial randomness ; independence ; random labeling ; spatial pattern
in this paper, we study the possibility of building two - field models of dark energy with equation of state across -1.   specifically we will consider two classes of models : one consists of two scalar fields ( quintessence + phantom ) and another includes one scalar ( phantom ) and one spinor field ( neutrino ).   our studies indicate to some extent that two - field models give rise to a simple realization of the dynamical dark energy model with the equation of state across @xmath0.
star - forming galaxies are predicted to contribute considerably to the cosmic gamma - ray background ( cgb ) as they are confirmed @xmath0-ray emitters and are the most numerous population of @xmath0-ray sources, although individually faint.   even though the _ fermi gamma - ray space telescope _ will be able to resolve few star - forming galaxies individually, their fractional contribution to the cgb should become far more significant than it was for past measurements of the cgb as many of the brighter, formerly unresolved sources will be resolved out.   thus, the clustering feature of galaxies imprinted on the cgb might be detectable by _ fermi_. in anticipation of such measurements, we calculate the predicted angular auto - power and cross - power spectra of the cgb from normal galaxies. we find that the amplitude of the auto - power spectrum is smaller than that for other sources such as blazars and dark - matter annihilation ; the shape is also characteristic.   we also show that the cross - power spectrum with galaxy surveys features larger amplitude.   _ fermi _ should be able to detect the correlation signature in both the auto - power and cross - power spectra at angular scales of @xmath1110@xmath2 after 5-yr of operation.   such a detection would be valuable in confirming the level of the star - forming galaxy contribution to the cgb, and more importantly, in serving as a tool in the effort to discriminate between possible origins of the cgb.       gamma rays : theory  large - scale structure of universe  galaxies : evolution  cosmology : theory.
short duration gamma - ray bursts are thought to originate from the coalescence of neutron stars in binary systems.   they are detected as a brief ( @xmath0 2s ), intense flash of gamma - ray radiation followed by a weaker, rapidly decreasing afterglow.   they are expected to be detected by advanced ligo and virgo when their sensitivity will be low enough. in a recent study @xcite   we identified a population of short gamma - ray bursts that are intrinsically faint and nearby. here   we provide evidence in favor of the existence of this new population that can hardly be reproduced with a model of field neutron star binary coalescences.   we propose that these systems may be produced dynamically in globular clusters, and may result from the merger of a black hole and a neutron star.   the advanced ligo and virgo observation of a high rate of nsbh mergers compatible with the dynamical formation in globular clusters would be a confirmation of this hypothesis and would enable for the derivation of the mass function of black holes inside globular clusters, as well as the luminosity function of faint short grbs.
we analyze the processes relevant for star formation in a model with dark matter in the form of sterile neutrinos.   sterile neutrino decays produce an x - ray background radiation that has a two - fold effect on the collapsing clouds of hydrogen.   first, the x - rays ionize the gas and cause an increase in the fraction of molecular hydrogen, which makes it easier for the gas to cool and to form stars.   second, the same x - rays deposit a certain amount of heat, which could, in principle, thwart the cooling of gas.   we find that, in all the cases we have examined, the overall effect of sterile dark matter is to facilitate the cooling of gas.   hence, we conclude that dark matter in the form of sterile neutrinos can help the early collapse of gas clouds and the subsequent star formation.
the metal  insulator transition ( mit ) for the square, simple cubic, and body - centered cubic lattices is investigated within the @xmath0@xmath1 hubbard model at half  filling by using both the generalized for the case of spiral order hartree   fock approximation ( hfa ) and kotliar  ruckenstein slave - boson approach.   it turns out that magnetic scenario of mit becomes superior over non - magnetic one.   the electron correlations lead to some suppression of the spiral phases in comparison with hfa.   we found the presence of metallic antiferromagnetic ( spiral ) phase in the case of three - dimensional lattices.
we study the nonlinear dynamics of collective excitation in a @xmath0-site @xmath1 quantum spin chain, which is manipulated by an oblique magnetic field.   we show that, when the tilted field is applied along the magic angle @xmath2, the anisotropic heisenberg spin chain becomes isotropic and thus an free propagating spin wave is stimulated.   and in the regime of the tilted angle larger and smaller then the magic angle, two types of nonlinear excitations appear, which are bright soliton and dark soliton.
employing a 40-kw, 54.1 mhz radio - frequency transmitter just west of delta, ut, the tara ( telescope array radar ) experiment seeks radar detection of extensive air showers ( eas ) initiated by ultra - high energy cosmic rays ( uhecr ).   for uhecr with energies in excess of @xmath0 ev, the doppler - shifted `` chirps '' resulting from eas shower core radar reflections should be observable above background ( dominantly galactic ) at distances of tens of km from the tara transmitter. in order to stereoscopically reconstruct cosmic ray chirps, two remote,   autonomous self - powered receiver stations have been deployed.   each remote station ( rs ) combines both low power consumption as well as low cost. triggering logic, the powering and communication systems, and some specific details of hardware components   are discussed.   = 1    cosmic ray, fpga, radar, digital signal processing, chirp
the shear modulus @xmath0 of two glass - forming colloidal model systems in @xmath1 and @xmath2 dimensions is investigated by means of, respectively, molecular dynamics and monte carlo simulations. comparing ensembles where either the shear strain @xmath3 or the conjugated ( mean ) shear stress @xmath4 are imposed,   we compute @xmath0 from the respective stress and strain fluctuations as a function of temperature @xmath5 while keeping a constant normal pressure @xmath6.   the choice of the ensemble is seen to be highly relevant for the shear stress fluctuations @xmath7 which at constant @xmath4 decay monotonously with @xmath5 following the affine shear elasticity @xmath8, i.e. a simple two - point correlation function. at variance,   non - monotonous behavior with a maximum at the glass transition temperature @xmath9 is demonstrated for @xmath7 at constant @xmath3.   the increase of @xmath0 below @xmath9 is reasonably fitted for both models by a continuous cusp singularity, @xmath10, in qualitative agreement with some recent replica calculations.   it is argued, however, that longer sampling times may lead to a sharper transition. the additive jump discontinuity predicted by mode - coupling theory and other replica calculations thus can not ultimately be ruled out.
entanglement and entanglement - assisted are useful resources to enhance the mutual information of the pauli channels, when the noise on consecutive uses of the channel has some partial correlations. in this paper, we study quantum communication channels with correlated noise and derive a general expression for the mutual information of quantum channel, for the product, maximally entangled state coding and entanglement - assisted systems with correlated noise in the pauli quantum channels. hence, we suggest more efficient coding in the entanglement - assisted systems for the transmission of classical information and derive a general expression for the entanglement - assisted classical capacity.   our results show that in the presence of memory, a higher amount of classical information is transmitted by two or four consecutive uses of entanglement - assisted systems.
the title `` time asymmetric quantum theory : the theory of resonances '' ( without questionmark ) of the cfif workshop ( 23.26.7.2003, lisbon, portugal ) implies that the theoretical description of resonances is uniquely described by the formalism of a.  bohm et al.   @xcite reflecting the title of the workshop.   our presentation in this workshop tries to introduce an apparently inequivalent, alternative feasible relativistic formalism provided by the author @xcite under the name `` ( anti)causal quantum theory '' ( ( a)cqt ) which is compared to the former.
galaxy comoving number density is commonly used to forge progenitor / descendant links between observed galaxy populations at different epochs.   however, this method breaks down in the presence of galaxy mergers, or when galaxies experience stochastic growth rates.   we present a simple analytic framework to treat the physical processes that drive the evolution and diffusion of galaxies within comoving number density space. the evolution in mass rank order of a galaxy population with time   is influenced by the galaxy coagulation rate and galaxy `` mass rank scatter '' rate.   we quantify the relative contribution of these two effects to the mass rank order evolution.   we show that galaxy coagulation is dominant at lower redshifts and stellar masses, while scattered growth rates dominate the mass rank evolution at higher redshifts and stellar masses. for a galaxy population at @xmath0,   coagulation has been the dominant effect since @xmath1, but a galaxy population at @xmath2 was dominated by mass rank scatter until @xmath3.   we show that although the forward and backward median number density evolution tracks are asymmetric, the backward median number density evolution can be obtained by convolving the descendant distribution function with progenitor relative abundances.   we tabulate fits for the median number density evolution and scatter which can be applied to improve the way galaxy populations are linked in multi - epoch observational datasets.   galaxies : abundances  galaxies : formation  galaxies : evolution  galaxies : statistics  methods : numerical
a number of physical phenomena are described by nonlinear hyperbolic equations.   presence of discontinuous solutions motivates the necessity of development of reliable numerical methods based on the fundamental mathematical properties of hyperbolic systems.   construction of such methods for systems more complicated than the euler gas dynamic equations requires the investigation of existence and uniqueness of the self - similar solutions to be used in the development of discontinuity - capturing high - resolution numerical methods.   this frequently necessitates the study of the behavior of discontinuities under vanishing viscosity and dispersion.   we discuss these problems in the application to the magnetohydrodynamic equations, nonlinear waves in elastic media, and electromagnetic wave propagation in magnetics.   # 1#2 # 1#2 # 1#2 # 1=#1= = = " 7630
we propose a new formation mechanism ( direct - supernova ) for low - mass x - ray binaries ( lmxbs ) that does not involve any prior phase of mass transfer.   survival through the supernova ( sn ) explosion and shrinkage of the orbit is achieved by a kick velocity of appropriate magnitude and direction imparted to the neutron star at its birth.   we present analytical population synthesis calculations of lmxbs forming via both the direct - sn and the helium - star sn mechanisms, and compare the results.   we find that the direct - sn channel contributes a non - negligible fraction of the total lmxb population, depending strongly on the r.m.s.   magnitude of the kick velocity.   more importantly, the direct - sn mechanism provides a natural way for the formation of low - mass binary pulsars in nearly circular orbits with orbital periods in excess of @xmath0, which can not have been formed via the helium - star sn mechanism.    to appear in _ the astrophysical journal _
the dynamical instabilities and ensuing dynamics of singly- and doubly - quantized vortex states of bose - einstein condensates with attractive interactions are investigated using full 3d numerical simulations of the gross - pitaevskii equation. with increasing the strength of attractive interactions, a series of dynamical instabilities such as quadrupole, dipole, octupole, and   monopole instabilities emerge.   the most prominent instability depends on the strength of interactions, the geometry of the trapping potential, and deviations from the axisymmetry due to external perturbations.   singly - quantized vortices split into two clusters and subsequently undergo split - merge cycles in a pancake - shaped trap, whereas the split fragments immediately collapse in a spherical trap.   doubly - quantized vortices are always unstable to disintegration of the vortex core.   if we suddenly change the strength of interaction to within a certain range, the vortex splits into three clusters, and one of the clusters collapses after a few split - merge cycles.   the vortex split can be observed using a current experimental setup of the mit group.
electricity transmission networks dissipate a non - negligible fraction of the power they transport due to the heat loss in the transmission lines. in this work   we explore how the transport of energy can be more efficient by adding to the network multiple batteries that can coordinate their operations.   such batteries can both charge using the current excess in the network or discharge to meet the network current demand.   either way, the presence of batteries in the network can be leveraged to mitigate the intrinsic uncertainty in the power generation and demand and, hence, transport the energy more efficiently through the network.   we consider a resistive dc network with stochastic external current injections or consumptions and show how the expected total heat loss depends on the network structure and on the batteries operations.   furthermore, in the case where the external currents are modeled by ornstein - uhlenbeck processes, we derive the dynamical optimal control for the batteries over a finite time interval.   = 1
we investigate density fluctuations in a coherent ensemble of interacting fermionic atoms. adapting the concept of full counting statistics, well - known from quantum optics and mesoscopic electron transport, we study second - order as well as higher - order correlators of density fluctuations. using the mean - field bcs state to describe the whole interval between the bcs limit and the bec limit  , we obtain an exact expression for the cumulant - generating function of the density fluctuations of an atomic cloud. in the two - dimensional case  , we obtain a closed analytical expression.   poissonian fluctuations of a molecular condensate on the bec side are strongly suppressed on the bcs side.   the size of the fluctuations in the bcs limit is a direct measure of the pairing potential.   we also discuss the bec - bcs crossover of the third cumulant and the temperature dependence of the second cumulant.
wavefunction extrapolation greatly reduces the number of self - consistent field ( scf ) iterations and thus the overall computational cost of born - oppenheimer molecular dynamics ( bomd ) that is based on the kohn  sham density functional theory.   going against the intuition that the higher order of extrapolation possesses a better accuracy, we demonstrate, from both theoretical and numerical perspectives, that the extrapolation accuracy firstly increases and then decreases with respect to the order, and an optimal extrapolation order in terms of minimal number of scf iterations always exists. we also prove that the optimal order tends to be larger when using larger md time steps or more strict scf convergence criteria.   by example bomd simulations of a solid copper system, we show that the optimal extrapolation order covers a broad range when varying the md time step or the scf convergence criterion.   therefore, we suggest the necessity for bomd simulation packages to open the user interface and to provide more choices on the extrapolation order.   another factor that may influence the extrapolation accuracy is the alignment scheme that eliminates the discontinuity in the wavefunctions with respect to the atomic or cell variables.   we prove the equivalence between the two existing schemes, thus the implementation of either of them does not lead to essential difference in the extrapolation accuracy.
this paper presents a novel analysis of the action / energy density distribution around a static quark - antiquark pair in su(3 ) lattice quantum chromodynamics. using the fourier transformation of the link variable  , we remove the high - momentum gluon and extract the flux - tube component from the action / energy density. when the high - momentum gluon is removed, the statistical fluctuation is drastically suppressed, and the singularities from the quark self - energy disappear.   the obtained flux - tube component is broadly distributed around the line connecting the quark and the antiquark.   lattice qcd, confinement, flux tube 11.15.ha, 12.38.aw, 12.38.gc
the ground - state three - quark ( 3q ) potential @xmath0 and the excited - state 3q potential @xmath1 are studied using su(3 ) lattice qcd at the quenched level. for more than 300 patterns of the 3q systems  , the ground - state potential @xmath0 is investigated in detail in lattice qcd with @xmath2 at @xmath3 and with @xmath4 at @xmath5. as a result  , the ground - state potential @xmath0 is found to be well described with y - ansatz within the 1%-level deviation. from the comparison with the q-@xmath6 potential, we find the universality of the string tension as @xmath7 and the one - gluon - exchange result as @xmath8.   the excited - state potential @xmath1 is also studied in lattice qcd with @xmath4 at @xmath9 for 24 patterns of the 3q systems.   the energy gap between @xmath0 and @xmath1, which physically means the gluonic excitation energy, is found to be about 1gev in the typical hadronic scale, which is relatively large compared with the excitation energy of the quark origin.   this large gluonic excitation energy justifies the great success of the simple quark model.
with the recent accelerating rate of discoveries in the field of nearby young stars, the ability to identify new nearby young stars is as important as ever, and membership identification codes will continue to perform a vital role in scientific research. in the process of creating a new moving group membership identification code - locating constituent members in nearby groups ( lacewing )   - we have compiled a few pointers relevant to astronomers trying to use codes like lacewing to locate young stars.
we discuss the hierarchy of yukawa couplings in a supersymmetric three family standard - like string model.   the model is constructed by compactifying type iia string theory on a @xmath0 orientifold in which the standard model matter fields arise from intersecting d6-branes. when lifted to m theory, the model amounts to compactification of m - theory on a @xmath1 manifold. while the actual fermion masses depend on the vacuum expectation values of the multiple higgs fields in the model, we calculate the leading worldsheet instanton contributions to the yukawa couplings and examine the implications of the yukawa hierarchy.   = 10000    # 1#2#3nucl.   phys.   b * # 1 *, # 3 ( 19#2 ) # 1#2#3phys.   lett.   b * # 1 *, # 3 ( 19#2 ) # 1#2#3phys.   lett.   # 1b, # 3 ( 19#2 ) # 1#2#3phys.   rev.   d * # 1 *, # 3 ( 19#2 ) # 1#2#3phys.   rev.   lett. *   # 1 *, # 3 ( 19#2 ) # 1#2#3phys. rep.   * # 1 * c, # 3 ( 19#2 ) # 1#2#3mod.  . lett. *   # 1 *, # 3 ( 19#2 )    # 1(#1 ) # 1#2
we have studied the atomic and magnetic structure of the dilute ferromagnetic semiconductor system  through atomic and magnetic pair distribution function analysis of temperature - dependent x - ray and neutron total scattering data.   we detected a change in curvature of the temperature - dependent unit cell volume of the average tetragonal crystallographic structure at a temperature coinciding with the onset of ferromagnetic order.   we also observed the existence of a well - defined local orthorhombic structure on a short length scale of @xmath0  , resulting in a rather asymmetrical local environment of the mn and as ions.   finally, the magnetic pdf revealed ferromagnetic alignment of mn spins along the crystallographic @xmath1-axis, with robust nearest - neighbor ferromagnetic correlations that exist even above the ferromagnetic ordering temperature.   we discuss these results in the context of other experiments and theoretical studies on this system.
in this paper we consider compactifications of type i strings on abelian orbifolds. we discuss the tadpole cancellation conditions for the general case with @xmath0-branes only.   such compactifications have ( perturbative ) heterotic duals which are also realized as orbifolds ( with non - standard embedding of the gauge connection ).   the latter have extra twisted states that become massive once orbifold singularities are blown - up.   this is due to the presence of _ perturbative _ heterotic superpotential with couplings between the extra twisted states, the orbifold blow - up modes, and ( sometimes ) untwisted matter fields.   anomalous @xmath1 ( generically present in such models ) also plays an important role in type i - heterotic ( tree - level ) duality matching.   we illustrate these issues on a particular example of @xmath2 orbifold type i model ( and its heterotic dual ).   the model has @xmath3 supersymmetry, @xmath4 gauge group, and chiral matter.   we also consider compactifications of type i strings on abelian orbifolds with both @xmath0- and @xmath5-branes.   we discuss tadpole cancellation conditions for a certain class of such models.   we illustrate the model building by considering a particular example of type i theory compactified on @xmath6 orbifold.   the model has @xmath3 supersymmetry, @xmath7 ^ 2 $ ] gauge group, and chiral matter.   this would correspond to a non - perturbative chiral vacuum from the heterotic point of view.   = 10000 epsf
sixty three members of the 100 myr old open cluster m47 ( ngc 2422 ) have been detected at 24@xmath0 with _   spitzer_. the be star v 378 pup shows an excess both in the near - infrared and at 24@xmath1 m ( @xmath2 =   2.4 $ ] mag ), probably due to free - free emission from the gaseous envelope.   seven other early - type stars show smaller excesses, @xmath2 = 0.6 - 0.9 $ ].    among late - type stars,   two show large excesses : p922  a k1v star with @xmath2   = 1.08 \pm 0.11 $ ] and p1121  an f9v star with @xmath2 = 3.72 \pm 0.02 $ ].   p1121 is the first known main - sequence star showing an excess comparable to that of @xmath3 pic, which may indicate the presence of an exceptionally massive debris disk.   it is possible that a major planetesimal collision has occurred in this system, consistent with the few hundred myr time scales estimated for the clearing of the solar system.
we consider the @xmath0 limit for tagged particle diffusion in a 1-dimensional rayleigh - gas, studied originaly by sinai and soloveichik @xcite, respectively by szsz and tth @xcite. in this limit   we derive a new type of model for tagged paricle diffusion, with calogero - moser - sutherland ( i.e. inverse quadratic ) interaction potential between the two central particles.   computer simulations on this new model reproduce exactly the numerical value of the limiting variance obtained by boldrighini, frigio and tognetti in @xcite.    _ dedicated to domokos szsz on his 65th birthday _
evolution formulas  of the density operator, the photon number distribution, and the wigner function are derived for the problem on the optical fields propagation in realistic environments.   the method of deriving these formulas is novel and the results are very useful for quantum optics and quantum statistics.
a description of dislocations and disclinations defects in terms of riemann  cartan geometry is given, with the curvature and torsion tensors being interpreted as the surface densities of the frank and burgers vectors, respectively.   a new free energy expression describing the static distribution of defects is presented, and equations of nonlinear elasticity theory are used to specify the coordinate system.   application of the lorentz gauge leads to equations for the principal chiral @xmath0-field. in the defect - free case  , the geometric model reduces to elasticity theory for the displacement vector field and to a principal chiral @xmath0-field model for the spin structure.   as illustrated by the example of a wedge dislocation, elasticity theory reproduces only the linear approximation of the geometric theory of defects.   it is shown that the equations of asymmetric elasticity theory for the cosserat media can also be naturally incorporated into the geometric theory as the gauge conditions. as an application of the theory, phonon scattering on a wedge dislocation   is considered.   the energy spectrum of impurity in the field of a wedge dislocation is also discussed.
in this contribution, first results of deep vlt photometry ( @xmath0 ) in the central region of the hydra  i and centaurus galaxy clusters are presented. in both galaxy clusters,   many star clusters have been identified down to the turnover magnitude of the globular cluster luminosity function at @xmath1 mag.   they are distributed not only around the several early - type galaxies, but also in the intra - cluster field, as far as 250 kpc from the cluster centers. outside the bulges of the central galaxies in hydra  i and centaurus,   the intra - cluster globular cluster system is dominated by blue clusters whose spatial distribution is similar to that of the ( newly discovered ) dwarf galaxies.
oh(1720 mhz ) masers unaccompanied by 1665/7 mhz line masers have recently been proposed as indicators of the interaction of supernova remnants ( snrs ) and molecular clouds.   we present a model for the masing region in which water produced in a c - type shock wave driven into the molecular cloud is dissociated as a result of the x - ray flux from the snr.   we note that the magnetic field strengths inferred from zeeman splitting of the 1720 mhz line measure the internal pressure of the supernova remnant.   in addition, we discuss the interaction of sgr a east, a snr candidate, with the 50 km / s cloud at the galactic centre and present near - infrared observations of  emission towards the regions where oh(1720 mhz ) maser emission is concentrated.   the magnetic field strength obtained from earlier zeeman measurements is consistent with rough pressure equilibrium between the postshock gas and the x - ray gas filling sgr a east detected by asca.   further, the intensity of the v=10 s(1 ) line of  is consistent with the shock strength expected to be driven into the molecular gas by this pressure.   the relative intensities of the  lines in sgr a east imply mainly collisional excitation.   # 1 10^#1 # 1 # 2 ^#2 u#1
we report here the discovery of an optical flare observed in r band from the red - dwarf eclipsing binary cu cnc whose component stars are at the upper boundary of full convection ( @xmath0 and @xmath1@xmath2, @xmath2 is the solar mass ).   the amplitude of the flare is the largest among those detected in r band ( @xmath3mag ) and the duration time is about 73 minutes. as those observed on the sun, quasi - periodic oscillations were seen during and after the flare.   three more r - band flares were found by follow up monitoring. in total, this binary was monitored photometrically by using r filter for 79.9hours, which reveals a r - band flare rate about 0.05 flares per hour.   these detections together with other strong chromospheric and coronal activities, i.e., very strong @xmath4 and @xmath5 emission features and an euv and x - ray source, indicate that it has very strong magnetic activity.   therefore, the apparent faintness ( @xmath61.4 magnitude in v ) of cu cnc compared with other single red dwarfs of the same mass can be plausibly explained by the high coverage of the dark spots.
we propose that the properties of glass transition can be understood on the basis of elastic waves.   elastic waves originating from atomic jumps in a liquid propagate local expansion due to the anharmonicity of interatomic potential.   this creates dynamic compressive stress, which increases the activation barrier for other events in a liquid.   the non - trivial point is that the range of propagation of high - frequency elastic waves, @xmath0, increases with liquid relaxation time @xmath1.   a self - consistent calculation shows that this increase gives the vogel - fulcher - tammann ( vft ) law. in the proposed theory, we discuss the origin of two dynamic crossovers in a liquid : 1 ) the crossover from exponential to non - exponential and from arrhenius to vft relaxation at high temperature and 2 ) the crossover from the vft to a more arrhenius - like relaxation at low temperature.   the corresponding values of @xmath1 at the two crossovers are in quantitative parameter - free agreement with experiments.   the origin of the second crossover allows us to reconcile the ongoing controversy surrounding the possible divergence of @xmath1.   the crossover to arrhenius relaxation universally takes place when @xmath0 reaches system size, thus avoiding divergence and associated theoretical complications such as identifying the nature of the phase transition and the second phase itself.   finally, we discuss the effect of volume on @xmath1 and the origin of liquid fragility.
simulation of chemical activity of corrugated graphene within density functional theory predicts an enhancement of its chemical activity if the ratio of height of the corrugation ( ripple ) to its radius is larger than 0.07.   further growth of the curvature of the ripples results in appearance of midgap states which leads to an additional strong increase of chemisororption energy.   these results open a way for tunable functionalization of graphene, namely, depending of curvature of the ripples one can provide both homogeneous ( for small curvatures ) and spot - like ( for large curvatures ) functionalization.    * *    * *    _ institute for molecules and materials, radboud university nijmegen,  heyendaalseweg 135, 6525 aj nijmegen, the netherlands _    _ e - mail : d.bukhvalov@science.ru.nl, m. katsnelson@science.ru.nl_
we show how defects in a spin chain described by the @xmath0 model may be used to generate entangled states, such as bell and @xmath1 states, and how to maintain them with high fidelity. in the presence of several excitations, we also discuss how the anisotropy of the system may be combined with defects to effectively assist in the creation of the desired states.
active particles contain internal degrees of freedom with the ability to take in and dissipate energy and, in the process, execute systematic movement.   examples include all living organisms and their motile constituents such as molecular motors.   this article reviews recent progress in applying the principles of nonequilibrium statistical mechanics and hydrodynamics to form a systematic theory of the behaviour of collections of active particles  active matter  with only minimal regard to microscopic details.   a unified view of the many kinds of active matter is presented, encompassing not only living systems but inanimate analogues.   theory and experiment are discussed side by side.   * this review is to appear in volume 1 of the annual review of condensed matter physics in july 2010 and is posted here with permission from that journal *    = 6.7 in = 9 in = 0.0 in = 0.0 in = 0.0 in = 0.0 in = 0.0 in = 0.2 in = 0.0 in    psfig.sty
using turbulent mhd simulations ( magnetic reynolds numbers up to @xmath0 ) and _ hinode _ observations, we study effects of turbulence on measuring the solar magnetic field outside active regions.   firstly, from synthetic stokes  @xmath1 profiles for the fei lines at 6301 and 6302 , we show that a peaked probability distribution function ( pdf ) for observationally - derived field estimates is consistent with a monotonic pdf for actual vertical field strengths.   hence, the prevalence of weak fields is greater than would be naively inferred from observations.   secondly, we employ the fractal self - similar geometry of the turbulent solar magnetic field to derive two estimates ( numerical and observational ) of the true mean vertical unsigned flux density.   we also find observational evidence that the scales of magnetic structuring in the photosphere extend at least down to the self - similar power - law scaling in the signed measure from a _ hinode _ magnetogram ranges ( over two decades in length scales and including the granulation scale ) down to the @xmath2 km resolution limit. from the self - similar scaling,   we determine a lower bound for the true quiet - sun mean vertical unsigned flux density of @xmath3 g.   this is consistent with our numerically - based estimates that 80% or more of the vertical unsigned flux should be invisible to stokes@xmath4 observations at a resolution of @xmath5 km owing to the cancellation of signal from opposite magnetic polarities.   our estimates significantly reduce the order - of - magnitude discrepancy between zeeman- and hanle - based estimates.
recent observations of quasars, mrk  335 and the quasar composite spectrum, have indicated that many of them have remarkably soft ionizing continua ( @xmath0, 13.6  ev  100  ev ).   we point out that the number of @xmath1 photons is insufficient to create the observed strengths of the emission lines.   while the numbers of photons which energize @xmath21549 and @xmath21034 are sufficient, even the most efficiently emitting clouds for these two lines must each cover at least 20%  40% of the source.   if the typical quasar ionizing continuum is indeed this soft, then we must conclude that the broad emission line clouds must see a very different ( harder ) continuum than we see.   the other viable possibility is that the uv  euv sed is double - peaked, with the second peaking near 54  ev, its wien tail the observed soft x - ray excess.   2ergss@xmath3@xmath4 5007@xmath5
we investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late - type galaxies using around 3740 published spectra of hii regions.   we use these data in order to provide homogeneous abundance determinations for all objects in the sample, including hii regions in which not all of the usual diagnostic lines were measured. examining the relation between n and o abundances in these galaxies   we find that the abundances in their centres and at their isophotal @xmath0 disk radii follow the same relation.   the variation in n / h at a given o / h is around 0.3 dex.   we suggest that the observed spread in n / h may be partly caused by the time delay between n and o enrichment and the different star formation histories in galaxies of different morphological types and dimensions.   we study the correlations between the abundance properties ( central o and n abundances, radial o and n gradients ) of a galaxy and its morphological type and dimension.
the notion of fejr monotonicity has proven to be a fruitful concept in fixed point theory and optimization. in this paper, we present new conditions sufficient for convergence of fejr monotone sequences and we also provide applications to the study of nonexpansive mappings.   various examples illustrate our results.    *   2010 mathematics subject classification : * primary 47h09 ; secondary 47h05, 90c25.   * keywords : * asymptotically regular sequence, fejr monotone sequence, nonexpansive mapping
previous approaches to the photo- and electro - production of strangeness off the proton, based upon effective hadronic lagrangians, are extended here to incorporate the so called _ off - shell effects _ inherent to the fermions with spin @xmath0.   a formalism for intermediate - state, spin 3/2, nucleonic and hyperonic resonances is presented and applied to the processes @xmath1, for @xmath2 2.5 gev, @xmath3, as well as the branching ratio for the crossed channel reaction @xmath4, with stopped kaons.   the sensitivity, from moderate to significant, of various observables to such effects are discussed.
we study the low - energy limit of a quarter - filled one - dimensional mott insulator.   we analytically determine the local density of states in the presence of a strong impurity potential, which is modeled by a boundary. to this end   we calculate the green function using field theoretical methods.   the fourier transform of the local density of states shows signatures of a pinning of the spin - density wave at the impurity as well as several dispersing features at frequencies above the charge gap.   these features can be interpreted as propagating spin and charge degrees of freedom.   their relative strength can be attributed to the `` quasi - fermionic '' behavior of charge excitations with equal momenta.   furthermore, we discuss the effect of bound states localized at the impurity. finally, we give an overview of the local density of states in various one - dimensional systems and discuss implications for scanning tunneling microscopy experiments.
we calculate the ground states and ground state phase diagrams of bose - einstein condensates of spin-3 atoms under the assumption of conserved magnetization.   we especially concentrate on the ground states of a @xmath0cr condensate. in @xmath0cr   the magnetic dipole - dipole interaction enables magnetization changing collisions, but in a strong magnetic field these are suppressed. in the calculation of the phase diagrams we neglect the contribution from the dipole - dipole interaction, but discuss its effects at the end of the paper.   we show that the ground state of a @xmath0cr condensate does not seem to depend on whether or not the dipole - dipole interaction is taken into attention.
a mechanism of disappearance and formation of the efimov levels of the helium @xmath0he trimer is studied when the force of the interatomic interaction is changed.   it is shown that these levels arise from virtual levels which are in turn formed from ( quasi)resonances settled on the real axis.   the resonances including virtual levels are calculated by the method based on the solution of the boundary value problem, at complex energies, for the faddeev differential equations describing the scattering processes @xmath1.   all the calculations are performed with the known interatomic aziz he   he- potential hfd - b. a very strong repulsive component of this potential at short distances between helium atoms is approximated by a hard core.   a special attention is paid to the substantiation of the method used for computing resonances and to the investigation of its applicability range.
we investigate confined lvy flights under premises of the principle of detailed balance.   the master equation admits a transformation to lvy - schrdinger semigroup dynamics ( akin to a mapping of the fokker - planck equation into the generalized diffusion equation ).   we solve a stochastic targeting problem for arbitrary stability index @xmath0 of lvy drivers : given an invariant probability density function ( pdf ), specify the jump - type dynamics for which this pdf is a long - time asymptotic target.   our (  @xmath1-targeting " ) method is exemplified by cauchy family and gaussian target pdfs.   we solve the reverse engineering problem for so - called lvy oscillators : given a quadratic semigroup potential, find an asymptotic pdf for the associated master equation for arbitrary @xmath1.
quantum criticality provides an important route to revealing universal non - equilibrium behaviour.   a canonical example of a quantum critical point is the bose - hubbard model, which we study under the application of an electric field.   a boltzmann transport formalism and @xmath0-expansion are used to obtain the non - equilibrium conductivity and current noise.   this approach allows us to explicitly identify how a universal non - equilibrium steady state is maintained, by identifying the rate - limiting step in balancing joule heating and dissipation to a heat bath.   it also reveals that the non - equilibrium distribution function is very far from a thermal distribution.
a method of moment inequalities is used to derive the principle of minimum growth rate in multiplicatively interacting stochastic processes(misps ).   when a value of a power - law exponent at the tail of probability distribution function exists in a range @xmath0, a first - order moment diverges and an equality for a growth rate of systems breaks down. from the estimate of inequalities, we newly find a conditional inequality which determines the growth rate, and then the exponent in @xmath0.
astrodynamical space test of relativity using optical devices i ( astrod i ) mainly aims at testing relativistic gravity and measuring the solar - system parameters with high precision, by carrying out laser ranging between a spacecraft in a solar orbit and ground stations. in order to achieve these goals,   the magnitude of the total acceleration disturbance of the proof mass has to be less than @xmath0ms@xmath1hz@xmath2 at 0.1mhz. in this paper  , we give a preliminary overview of the sources and magnitude of acceleration disturbances that could arise in the astrod i proof mass.   based on the estimates of the acceleration disturbances and by assuming a simple control - loop model, we infer requirements for astrod i. our estimates show that most of the requirements for astrod i can be relaxed in comparison with laser interferometer space antenna ( lisa ).
this paper theoretically studies the coherent control of photon transmission along the coupled resonator optical waveguide ( crow ) by doping artificial atoms in hybrid structures. we provide the several approaches correspondingly based on the mean field method and spin wave theory et al. in the present paper   we adopt the two - time green function approach to study the coherent transmission photon in a crow with homogeneous couplings, each cavity of which is doped by a two - level artificial atom.   we calculate the two - time correlation function for photon in the weak - coupling case.   its poles predict the exact dispersion relation, which results in the group velocity coherently controlled by the collective excitation of the doping atoms.   we emphasize the role of the population inversion of doping atoms induced by some polarization mechanism.
we study with exact diagonalization techniques the heisenberg model for a system of su(2 ) spins with @xmath0 and random infinite - range exchange interactions.   we calculate the critical temperature @xmath1 for the spin - glass to paramagnetic transition.   we obtain @xmath2, in good agreement with previous quantum monte carlo and analytical estimates.   we provide a detailed picture for the different kind of excitations which intervene in the dynamical response @xmath3 at @xmath4 and analyze their evolution as @xmath5 increases.   we also calculate the specific heat @xmath6.   we find that it displays a smooth maximum at @xmath7, in good qualitative agreement with experiments.   we argue that the fact that @xmath8 is due to a quantum disorder effect.
the goal of this paper is to survey the properties of the eigenvalue relaxation for least squares binary problems.   this relaxation is a convex program which is obtained as the lagrangian dual of the original problem with an implicit compact constraint and as such, is a convex problem with polynomial time complexity.   moreover, as a main pratical advantage of this relaxation over the standard semi - definite programming approach, several efficient bundle methods are available for this problem allowing to address problems of very large dimension.   the necessary tools from convex analysis are recalled and shown at work for handling the problem of exactness of this relaxation.   two applications are described.   the first one is the problem of binary image reconstruction and the second is the problem of multiuser detection in cdma systems.
we present an interesting monogamy equation for @xmath0-dimensional pure states, by which a quantity is found to characterize the tripartite entanglement with the ghz type and w type entanglements as a whole.   in particular, we, for the first time, reveals that for any quantum state of a pair of qubits, the difference between the two remarkable entanglement measures, concurrence and negativity, characterizes the w type entanglement of tripartite pure states with the two - qubit state as reduced density.   entanglement measure, monogamy, tripartite entanglement 03.67.mn,03.65.ud,03.65.ta
the setup of two different small scale teststands for measurements regarding an electron cherenkov detector as part of the ilc polarimeters is presented.   component measurements already carried out are analyzed and others, foreseen for the near future, are discussed.   the larger one of the two teststands features the old cherenkov detector of the sld experiment, which will be used as a reference for a number of crucial measurements.   especially, the requirements for the non - linearity of the read - out chain are studied in greater detail and methods for its precise measurement before and during operation are being developed accordingly.
one of the biggest challenges the current stt - ram industry faces is maintaining a high thermal stability while trying to switch within a given voltage pulse and energy cost. in this paper, we present a physics based model that uses a modified simmons tunneling expression to capture the spin dependent tunneling in a magnetic tunnel junction(mtj ).   coupled with an analytical derivation of the critical switching current based on the landau - lifshitz - gilbert equation, and the write error rate derived from a solution to the fokker - planck equation, this model provides us a quick estimate of the energy - delay - reliability tradeoffs in perpendicular sttrams. in other words,   the model provides a simple way to calculate the energy consumed during a write operation that ensures a certain error rate and delay time, while being numerically far less intensive than a full - fledged stochastic calculation.   we calculate the worst case energy consumption during anti - parallel ( ap ) to parallel ( p ) and p to ap switchings and quantify how increasing the anisotropy field @xmath0 and lowering the saturation magnetization @xmath1, can significantly reduce the energy consumption..   shell : bare demo of ieeetran.cls for journals    spin polarized transport, spin torque
in order to establish an objective framework for studying galaxy morphology, we have developed a quantitative two - parameter description of galactic structure that maps closely on to hubble s original tuning fork. any galaxy can be placed in this `` hubble space, '' where the @xmath0-coordinate measures position along the early - to - late sequence, while the @xmath1-coordinate measures in a quantitative way the degree to which the galaxy is barred.   the parameters defining hubble space are sufficiently robust to allow the formation of hubble s tuning fork to be mapped out to high redshifts. in the present paper  , we describe a preliminary investigation of the distribution of local galaxies in hubble space, based on the ccd imaging atlas of frei et al.(1996 ).   we find that barred, weakly - barred, and unbarred galaxies are remarkably well - separated on this diagnostic diagram.   the spiral sequence is clearly bimodal and indeed approximates a tuning fork : strongly - barred and unbarred spirals do not simply constitute the extrema of a smooth unimodal distribution of bar strength, but rather populate two parallel sequences. strongly barred galaxies lie on a remarkably tight sequence, strongly suggesting the presence of an underlying unifying physical process. rather surprisingly, weakly barred systems do not seem to correspond to objects bridging the parameter space between unbarred and strongly barred galaxies, but instead form an extension of the regular spiral sequence.   this relation lends support to models in which the bulges of late - type spirals originate from secular processes driven by bars.
slow relaxation and aging of the conductance are experimental features of a range of materials, which are collectively known as electron glasses.   we report dynamic monte carlo simulations of the standard electron glass lattice model. in a non - equilibrium state, the electrons will often form a fermi distribution with an effective electron temperature higher than the phonon bath temperature.   we study the effective temperature as a function of time in three different situations : relaxation after a quench from an initial random state, during driving by an external electric field and during relaxation after such driving.   we observe logarithmic relaxation of the effective temperature after a quench from a random initial state as well as after driving the system for some time @xmath0 with a strong electric field. for not too strong electric field and not too long @xmath0   we observe that data for the effective temperature at different waiting times collapse when plotted as functions of @xmath1  the so - called _   simple aging_. during the driving period we study how the effective temperature is established, separating the contributions from the sites involved in jumps from those that were not involved.   it is found that the heating mainly affects the sites involved in jumps, but at strong driving, also the remaining sites are heated.
we study the general chaotic features of dynamics of the phantom field modelled in terms of a single scalar field conformally coupled to gravity.   we demonstrate that the dynamics of the frw model with dark energy in the form of phantom field can be regarded as a scattering process of two types : multiple chaotic and classical non - chaotic.   it depends whether the spontaneously symmetry breaking takes place. in the first class of models with the spontaneously symmetry breaking the dynamics   is similar to the yang - mills theory.   we find the evidence of a fractal structure in the phase space of initial conditions.   we observe similarities to the phenomenon of a multiple scattering process around the origin. in turn   the class of models without the spontaneously symmetry breaking can be described as the classical non - chaotic scattering process and the methods of symbolic dynamic are also used in this case.   we show that the phantom cosmology can be treated as a simple model with scattering of trajectories which character depends crucially on a sign of a square of mass.   we demonstrate that there is a possibility of chaotic behavior in the flat universe with a conformally coupled phantom field in the system considered on non - zero energy level.   we obtain that the acceleration is a generic feature in the considered model without the spontaneously symmetry breaking.   we observe that the effective eos coefficient oscillates and then approach to @xmath0.
the bethe - salpeter equation in the diquark channel is investigated by employing the dyson - schwinger method together with the munczek - nemirovsky model.   the novelty of our study is a resummation of completely crossed ladder diagrams in the bethe - salpeter kernel.   these diagrams are enhanced due to their color factors in the diquark channel, but not in the meson channel. in our analysis, diquark bound - state solutions exist in the bethe - salpeter equation.   ut1505 + february, 2015    4 cm   * diquark bound states with a completely crossed ladder truncation * 0.7 in * ryusuke jinno *, * teppei kitahara *, and * go mishima * 0.5 in    0.1 in   .85 in   ''' ''   .2 in   ''' ''   .4 in
we present a theory of organic magnetoresistance ( omr ) based on the quenching of the quantum correlation between the carrier s spin and its local environment when the incoherent hopping takes place.   we prove that this process contributes a spin - dependent prefactor to the attempt - to - escape frequency in the hopping rate, with its value modulated by the magnetic field.   the resulting omr exhibits a positive lorentzian saturation component and a negative small - field component, which are independent of model parameters.   these behaviors, with their isotope effects, are in good agreement with experimental results.
recent work on the mass distribution in spiral galaxies, using mainly hi observations, is reviewed.   the principal problem is still to determine to what extent the dark matter is important in the inner parts of a galaxy, or in other words, how dominant is the self - gravitation of the disc.   studies of the shapes of rotation curves show that in detail there is sufficient individuality in spiral galaxies to prohibit the construction of `` universal rotation curves ''.   a detailed account is given of the method of athanassoula et al.   ( 1987 ), where swing amplifier criteria are applied to set a range in the mass - to - light ratio of the disc. to restrict this range further  , other methods might be useful.   for a number of bright spirals the rotation curve drops just outside the optical image, but this feature by itself can not constrain unambiguously the mass models.   the use of velocity dispersions seems a promising way, though the observational problems are hard. within the uncertainties  , discs can be close to `` maximum '', even though a range of values can not be excluded.
many critical properties of the hintermann - merlini model are known exactly through the mapping to the eight - vertex model.   wu [ j. phys.   c * 8 *, 2262 ( 1975 ) ] calculated the spontaneous magnetizations of the model on two sublattices by relating them to the conjectured spontaneous magnetization and polarization of the eight - vertex model, respectively.   the latter conjecture remains unproved. in this paper  , we numerically study the critical properties of the model by means of a finite - size scaling analysis based on transfer matrix calculations and monte carlo simulations.   all analytic predictions for the model are confirmed by our numerical results.   the central charge @xmath0 is found for critical manifold investigated.   in addition, some unpredicted geometry properties of the model are studied.   fractal dimensions of the largest ising clusters on two sublattices are determined.   the fractal dimension of the largest ising cluster on the sublattice a takes fixed value @xmath1, while that for sublattice b varies continuously with the parameters of the model.
motivated by recent observations of plateaus and minima in the radial abundance distributions of heavy elements in the milky way and some other spiral galaxies, we propose a dynamical mechanism for the formation of such features around corotation.   our numerical simulations show that the non - axisymmetric gravitational field of spiral density waves generates cyclone and anticylone gas flows in the vicinity of corotation.   the anticyclones flatten the pre - existing negative abundance gradients by exporting many more atoms of heavy elements outside corotation than importing inside it.   this process is very efficient and forms plateaus of several kiloparsec in size around corotation after two revolution periods of a galaxy.   the strength of anticyclones and, consequently, the sizes of plateaus depend on the pitch angle of spiral arms and are expected to increase along the hubble sequence.   ism : abundances - galaxies : abundances - galaxies : spiral
images present evidence for a non - uniform spatial distribution of discrete x - ray sources in the elliptical galaxy ngc  4261.   this non - uniform distribution is inconsistent with the optical morphology of ngc  4261 at greater than a 99.9% confidence level.   similar evidence is seen in one more elliptical galaxy ( ngc  4697 ; 98% confidence level ) out of five cases we investigated.   ngc  4261 and ngc  4697 have old stellar populations ( 9 - 15  gyrs ) and fine structure parameters of 1 and 0 respectively, suggesting no recent merging activity. on the basis of simulations of galaxy interactions, we propose that the x - ray sources responsible for the non - uniform distribution are associated with young stellar populations, related to the rejuvenating fall - back of material in tidal tails onto a relaxed merger remnant, or shock induced star - formation along the tidal tails.
recent observations by the _ swift _ satellite have revealed long - lasting ( @xmath0 ), `` plateau - like '' x - ray afterglows in the vast majority of short gamma - ray bursts events.   this has put forward the idea of a long - lived millisecond magnetar central engine being generated in a binary neutron star ( bns ) merger and being responsible for the sustained energy injection over these timescales ( `` magnetar model '' ).   we elaborate here on recent simulations that investigate the early evolution of such a merger remnant in general - relativistic magnetohydrodynamics.   these simulations reveal very different conditions than those usually assumed for dipole spin - down emission in the magnetar model. in particular, the surrounding of the newly formed ns is polluted by baryons due to a dense, highly magnetized and isotropic wind from the stellar surface that is induced by magnetic field amplification in the interior of the star. the timescales and luminosities of this wind   are compatible with early x - ray afterglows, such as the `` extended emission ''.   these isotropic winds are a generic feature of bns merger remnants and thus represent an attractive alternative to current models of early x - ray afterglows.   further implications to bns mergers and short gamma - ray bursts are discussed.
neutral stellar core at or over nuclear densities is described by a positive charged baryon core and negative charged electron fluid since they possess different masses and interactions. based on a simplified model of a gravitationally collapsing or pulsating baryon core  , we approximately integrate the einstein - maxwell equations and the equations for the number and energy - momentum conservation of complete degenerate electron fluid.   we show possible electric processes that lead to the production of electron - positron pairs in the boundary of a baryon core and calculate the number and energy of electron - positron pairs. this can be relevant for understanding the energetic sources of supernovae and gamma - ray bursts.
the cosmological parameters that i will emphasize are the hubble parameter @xmath0 km s@xmath1 mpc@xmath1, the age of the universe @xmath2, the average matter density @xmath3, the baryonic matter density @xmath4, the neutrino density @xmath5, and the cosmological constant @xmath6. the evidence currently favors @xmath7 gyr, @xmath8, @xmath9, @xmath10, @xmath11, and @xmath12.
.1 cm quaternionic polynomials are generated by quaternionic variables and the quaternionic product.   this paper proposes the generating ideal of quaternionic polynomials in tensor algebra, finds the grbner base of the ideal in the case of pure imaginary quaternionic variables, and describes the normal forms of such quaternionic polynomials explicitly.
recent advances in the photon tagging facilities together with the novel, high resolution fast calorimetry made possible to perform photoproduction cross section measurements of pseudoscalar mesons on nuclei with a percent level accuracy.   the extraction of the radiative decay widths, needed for testing the symmetry breaking effects in qcd, from these measurements at small angles is done by the primakoff method.   this method requires theoretical treatment of all processes participating in these reactions at the same percent level.   the most updated description of general processes, including the nuclear coherent amplitude, is done in our previous paper. in this work, based on the framework of glauber multiple scattering theory  , we obtain analytical expressions for the incoherent cross section of the photoproduction of pseudoscalar mesons off nuclei accounting for the mesons absorption in nuclei and pauli suppression at forward production angles. as illustrations of the obtained formulas  , we calculate the incoherent cross section for photoproduction from a closed shell nucleus, @xmath0o, and from an unclosed shell nucleus, @xmath1c.   these calculations allow one to compare different approaches and estimate their impact on the incoherent cross section of the processes under consideration.
the single stable isotope of beryllium is a pure product of cosmic - ray spallation in the ism. assuming that the cosmic - rays are globally transported across the galaxy, the beryllium production should be a widespread process and   its abundance should be roughly homogeneous in the early - galaxy at a given time.   thus, it could be useful as a tracer of time. in an investigation of the use of   be as a cosmochronometer and of its evolution in the galaxy, we found evidence that in a log(be / h ) vs.  diagram the halo stars separate into two components.   one is consistent with predictions of evolutionary models while the other is chemically indistinguishable from the thick - disk stars.   this is interpreted as a difference in the star formation history of the two components and suggests that the local halo is not a single uniform population where a clear age - metallicity relation can be defined.   we also found evidence that the star formation rate was lower in the outer regions of the thick disk, pointing towards an inside - out formation.
the revision of the photospheric abundances proferred by asplund et al has rendered opacity theory inconsistent with the seismologically determined opacity through the sun.   this highlights the need for a direct seismological measurement of solar abundances.   here we describe the technique used to measure abundances with seismology, examine our ability to detect differences between solar models using this technique, and discuss its application in the sun.
dark matter caustics are small scale, high density structures believed to exist in galaxies like ours.   if the dark matter consists of weakly interacting massive particles, these caustics may be detected by means of the gamma rays produced by dark matter particle annihilation.   we discuss particle annihilation in outer and inner caustics and provide sky maps of the expected gamma ray distribution.
we investigate the chaotic inflationary model using the two - loop effective potential of a self - interacting scalar field theory in curved spacetime.   we use the potential which contains a non - minimal scalar curvature coupling and a quartic scalar self - interaction and which was found in ref.   @xcite.   we analyze the lyapunov stability of de sitter solution and show the stability bound. calculating the inflationary parameters, we systematically explore the spectral index @xmath0 and the tensor - to - scalar ratio @xmath1, with varying the four parameters, the scalar - curvature coupling @xmath2, the scalar quartic coupling @xmath3, the renormalization scale @xmath4 and the e - folding number @xmath5. it is found that the two - loop correction on @xmath0 is much larger than the leading - log correction, which has previously been studied in ref.   @xcite.   we show that the model is consistent with the observation by planck with wmap @xcite and a recent joint analysis of bicep2 @xcite.    _ keyword : _ two - loop effective potential, spectral index, tensor - to - scalar ratio    _ pacs : _   11.10.-z, 04.62.+v, 98.80.cq
we present here a generalization of the thermal discrete dipole approximation ( tdda ) that allows us to describe the near - field radiative heat transfer between finite objects of arbitrary shape that exhibit magneto - optical ( mo ) activity.   we also extend the tdda approach to describe the thermal emission of a finite object with and without mo activity.   our work not only generalizes the existent tdda approach to the case of non - reciprocal systems, but it also corrects basic inconsistencies in previous formulations.   moreover, we show that employing our tdda approach one can rigorously demonstrate kirchhoff s radiation law relating the emissivity and absorptivity of an arbitrary mo object.   our work paves the way for the theoretical study of the active control of emission and radiative heat transfer between mo systems of arbitrary size and shape.
the remagnetization dynamics of monolayer dot array superlattice xy 2-d spin model with dipole - dipole interactions is simulated. within the proposed model of array,   the square dots are described by the spatially modulated exchange - couplings.   the dipole - dipole interactions are approximated by the hierarchical sums and spin dynamics is considered in regime of the landau - lifshitz equation.   the simulation of reversal for @xmath0 spins exhibits formation of nonuniform intra - dot configurations with nonlinear wave / anti - wave pairs developed at intra - dot and inter - dot scales.   several geometric and parametric dependences are calculated and compared with oversimplified four - spin model of reversal.   the role of initial conditions and the occurrence of coherent rotation mode is also investigated.   the emphasis is on the classification of intra - dot or inter - dot ( interfacial ) magnetic configurations done by adaptive neural network with varying number of neurons.   pacs : nanostructures : 79.60.j, magnetostatics 41.20.g, magnetic ordering 75.10, numerical simulation studies 75.40.mg    key words : magnetic dot array, neural network model, xy model, numerical simulation
the reasons of the crisis in the contemporary ( riemannian ) geometry are discussed.   the conventional method of the generalized geometries construction, based on a use of the topology, leads to a overdetermination of the riemannian geometry.   in other words, at the riemannian geometry construction one uses the needless information ( topology ), which disagrees with other original axioms.   the crisis manifests in the fact, that the mathematical community can not see and does not want to see the overdetermination of the riemannian geometry.   the most geometers - topologists deny the alternative method of the generalized geometry construction, which does not uses the topology, because it does not contain theorems.   most geometers see the geometry presentation as a set of definitions and theorems.   they can not imagine the geometry presentation without customary theorems. as a result   the most clever topologists, which have acknowledged the negligible role of the topology in the geometry construction and inconsistency of the conventional method of the generalized geometry construction, appear in the difficult situation ( conflict with the mathematical community ).
the lyman continuum photon production efficiency ( @xmath0 ) is a critical ingredient for inferring the number of photons available to reionise the intergalactic medium. to estimate the theoretical production efficiency in the high - redshift universe we couple the bluetides cosmological hydrodynamical simulation with a range of stellar population synthesis models.   we find lyman continuum photon production efficiencies of @xmath1 depending on the choice of stellar population synthesis model.   these results are broadly consistent with recent observational constraints at high - redshift though favour a model incorporating the effects of binary evolution.   
polarization is the next frontier of cmb analysis, but its signal is dominated over much of the sky by foregrounds which must be carefully removed. to determine the efficacy of this cleaning it is necessary to have sensitive tests for residual foreground contamination in polarization sky maps.   the dominant galactic foregrounds introduce a large - scale anisotropy on to the sky, so it makes sense to use a statistic sensitive to overall directionality for this purpose. here   we adapt the rapidly computable @xmath0 statistic of bunn and scott to polarization data, and demonstrate its utility as a foreground monitor by applying it to the low resolution _ wmap _  3-yr sky maps. with a thorough simulation of the maps noise properties  , we find no evidence for contamination in the foreground cleaned sky maps.       cosmic microwave background   methods : numerical  cosmology : observations  cosmology : theory  large - scale structure
the propagation of azimuthally symmetric guided waves in multiwalled carbon nanotubes ( mwcnts ) was analyzed theoretically in the mid - infrared and the visible regimes.   the mwcnts were modeled as ensembles of concentric, cylindrical, conducting shells. slightly attenuated   guided waves and antenna resonances due to the edge effect exist for not - too - thick mwcnts in the far- and mid - infrared regimes.   interband transitions hinder the propagation of guided waves and have a deleterious effect on the performance of a finite - length mwcnt as an antenna.   propagation of surface - plasmon waves along an mwcnt with a gold core was also analyzed. in   the near - infrared and the visible regimes, the shells behave effectively as lossy dielectrics suppressing surface - plasmon - wave propagation along the gold core.
the influence of gaussian laser pulses on the transport through molecular wires is investigated within a tight - binding model for spinless electrons including correlation. motivated by the phenomenon of coherent destruction of tunneling for monochromatic laser fields  , situations are studied in which the maximum amplitude of the electric field fulfills the conditions for the destructive quantum effect.   it is shown that, as for monochromatic laser pulses, the average current through the wire can be suppressed. for parameters of the model, which do not show a net current without any optical field,   a gaussian laser pulse can establish a temporary current.   in addition, the effect of electron correlation on the current is investigated.
we present cross sections and reaction rates for merging to occur during encounters of equal - mass spherical galaxies. as an application  , we determine the rate of galaxy merging in clusters of galaxies.   we present results for two types of plummer models ( a full and a truncated one ), two king models and the hernquist model.   cross sections are determined on the basis of a large number ( @xmath0 ) of simulations of galaxy encounters, using the 10-gigaflops grape 3a special - purpose computer.   we characterize the overall merger rate of galaxies in a galaxy cluster by a single number, derived from our cross sections by an integration over galaxy encounter velocities in the limit of a constant density in velocity space. for small clusters, where the cluster velocity dispersion may not significantly exceed the internal velocity dispersion of the individual galaxies,   this constant - density approximation may not be valid.   for those cases, we present separate results, based on integrations of our cross sections over maxwellian velocity distributions.   finally, tidal effects from the cluster potential as well as from neighboring galaxies may prevent a barely bound galaxy pair from spiraling in after their first encounter.   we give a quantitative estimate of the resulting reduction in the actual merger rate, due to these tidal interactions.   # 1@xmath1 # 1@xmath2 # 1* * # 1* * = cmbx10 scaled 2 plus 2pt
a procedure to characterize chaotic dynamical systems with concepts of complex networks is pursued, in which a dynamical system is mapped onto a network.   the nodes represent the regions of space visited by the system, while edges represent the transitions between these regions.   parameters used to quantify the properties of complex networks, including those related to higher order neighborhoods, are used in the analysis.   the methodology is tested for the logistic map, focusing the onset of chaos and chaotic regimes.   it is found that the corresponding networks show distinct features, which are associated to the particular type of dynamics that have generated them.   _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 89.75.fb : structures and organization in complex systems + 89.75.hc : networks and genealogical trees + 02.10.ox : combinatorics ; graph theory _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
molecular dynamics computer simulations are used to investigate the dynamics of a binary mixture of charged ( yukawa ) particles with a size  ratio of 1:5.   we find that the system undergoes a phase transition where the large particles crystallize while the small particles remain in a fluid  like ( delocalized ) phase.   upon decreasing temperature below the transition, the small particles become increasingly localized on intermediate time scales.   this is reflected in the incoherent intermediate scattering functions by the appearance of a plateau with a growing height. at long times,   the small particles show a diffusive hopping motion.   we find that these transport properties are related to structural correlations and the single  particle potential energy distribution of the small particles.
this paper reviews the state of the art in spin - torque and spin hall effect driven nano - oscillators. after a brief introduction to the underlying physics,   the authors discuss different implementations of these oscillators, their functional properties in terms of frequency range, output power, phase noise, and modulation rates, and their inherent propensity for mutual synchronization.   finally, the potential for these oscillators in a wide range of applications, from microwave signal sources and detectors to neuromorphic computation elements, is discussed together with the specific electronic circuitry that has so far been designed to harness this potential.   = 1    spintronics, microwaves, spin transfer torque, spin hall effect.
we investigate the flavour decomposition of the electromagnetic form factors of the nucleon, based on the chiral quark - soliton model ( @xmath0qsm ) with symmetry - conserving quantisation.   we consider the rotational @xmath1 and linear strange - quark mass ( @xmath2 ) corrections.   we discuss the results of the flavour - decomposed electromagnetic form factors in comparison with the recent experimental data. in order to see the effects of the strange quark  , we compare the su(3 ) results with those of su(2 ).   we finally discuss the transverse charge densities for both unpolarised and polarised nucleons.   the transverse charge density inside a neutron turns out to be negative in the vicinity of the centre within the su(3 ) @xmath0qsm, which can be explained by the contribution of the strange quark.
we investigate simulated turbulent flow within thermally driven stellar convection zones.   different driving sources are studied, including cooling at the top of the convectively unstable region, as occurs in surface convection zones ; and heating at the base by nuclear burning.   the transport of enthalpy and kinetic energy, and the distribution of turbulent kinetic energy dissipation are studied.   we emphasize the importance of global constraints on shaping the quasi - steady flow characteristics, and present an analysis of turbulent convection which is posed as a boundary value problem that can be easily incorporated into standard stellar evolution codes for deep, efficient convection.   direct comparison is made between the theoretical analysis and the simulated flow and very good agreement is found.   some common assumptions traditionally used to treat quasi - steady turbulent flow in stellar models are briefly discussed.   the importance and proper treatment of convective boundaries are indicated.
semi - analytical model for calculating acoustic response to a line - focused laser pulse in an optically absorptive isotropic cylinder is proposed and implemented.   it is assumed that the laser input is absorbed over the volume and thus creates a radially distributed thermoelastic source.   closed - form solution is obtained in the fourier domain.   two inverse fourier transforms in frequency and circumferential wave number yield the sought waveforms of acoustic response in the time - space domain.   numerical simulation is compared to the calculation based on a surface dipole source.   the two signals have essentially different shapes of the wave - arrival peaks when the optical penetration is large enough.   keywords : laser ultrasonics, distributed thermoelastic source, acoustic responce, cylinder
the mass spectra and electromagnetic decay rates of charmonium, bottomonium and @xmath0 mesons are comprehensively investigated in the relativistic quark model.   the presence of only heavy quarks allows the expansion in powers of their velocities.   all relativistic corrections of order @xmath1, including retardation effects and one - loop radiative corrections, are systematically taken into account in the computations of the mass spectra.   the obtained wave functions are used for the calculation of radiative magnetic dipole ( m1 ) and electric dipole ( e1 ) transitions.   it is found that relativistic effects play a substantial role.   their account and the proper choice of the lorentz structure of the quark - antiquark interaction in a meson is crucial for bringing theoretical predictions in accord with experimental data.   a detailed comparison of the calculated decay rates and branching fractions with available experimental data for radiative decays of charmonium and bottomonium is presented. the possibilities to observe the currently missing spin - singlet @xmath2 and @xmath3 states as well as @xmath4 states in bottomonium   are discussed.   the results for @xmath0 masses and decays are compared with other quark model predictions.
we prove a theorem on the magnetic energy minimum in a system of perfect, or ideal, conductors.   it is analogous to thomson s theorem on the equilibrium electric field and charge distribution in a system of conductors.   we first prove thomson s theorem using a variational principle.   our new theorem is then derived by similar methods.   we find that magnetic energy is minimized when the current distribution is a surface current density with zero interior magnetic field ; perfect conductors are perfectly diamagnetic.   the results agree with currents in superconductors being confined near the surface.   the theorem implies a generalized force that expels current and magnetic field from the interior of a conductor that loses its resistivity.   examples of solutions that obey the theorem are presented.
in the context of averaging an inhomogeneous cosmological model, we propose a natural measure identical to the kullback - leibler relative information entropy, which expresses the distinguishability of the local inhomogeneous density field from its spatial average on arbitrary compact domains.   this measure is expected to be an increasing function in time and thus to play a significant role in studying gravitational entropy. to verify this conjecture,   we explore the time evolution of the measure using the linear perturbation theory of a spatially flat flrw model and a spherically symmetric nonlinear solution.   we discuss the generality and conditions for the time - increasing nature of the measure, and also the connection to the backreaction effect caused by inhomogeneities.   address = department of material science and technology, nagaoka university of technology, 1603 - 1 kamitomioka, nagaoka, niigata 940 - 2188, japan     address = universit lyon 1, centre de recherche astrophysique de lyon, cnrs umr 5574, 9 avenue charles andr, f-69230 saint - genis - laval, france     address = department of physics, tokyo institute of technology, oh - okayama, meguro, tokyo 152 - 8551, japan     address = center for particle physics and phenomenology, universit catholique de louvain, 2 chemin du cyclotron, b-1348 louvain - la - neuve, belgium
quite a few low - dimensional magnets are quantum - disordered `` spin liquids '' with a characteristic gap in the magnetic excitation spectrum. among these are antiferromagnetic chains of integer quantum spins.   their generic feature are long - lived massive ( gapped ) excitations ( magnons ) that are subject to zeeman splitting in external magnetic fields.   the gap in one of the magnon branches decreases with field, driving a soft - mode quantum phase transition.   the system then enters a qualitatively new high - field phase.   the actual properties at high fields, particularly the spin dynamics, critically depend on the system under consideration.   recent neutron scattering studies of organometallic polymer crystals ndmap ( haldane spin chains with anisotropy ) and ntenp ( dimerized @xmath0 chains ) revealed rich and unique physics.   address = condensed matter sciences division, oak ridge national laboratory, oak ridge, tn 37831 - 6393, usa.
we introduce and analyze a class of growing geometric random graphs that are invariant under rescaling of space and time. directed connections between nodes are drawn according to influence zones that depend on node position in space and time, mimicking the heterogeneity and increased specialization found in growing networks. through calculations and numerical simulations we explore the consequences of scale - invariance for geometric graphs generated this way.   our analysis reveals a dichotomy between scale - free and poisson distributions of in- and out - degree, the existence of a random number of hub nodes, high clustering, and unusual percolation behaviour.   these properties are similar to those of empirically observed web graphs.
we consider effects of a periodic modulation of the nonlinearity coefficient on fundamental and higher - order solitons in the one - dimensional nls equation, which is an issue of direct interest to bose - einstein condensates in the context of the feshbach - resonance control, and fiber - optic telecommunications as concerns periodic compensation of the nonlinearity.   we find from simulations, and explain by means of a straightforward analysis, that the response of a fundamental soliton to the weak perturbation is resonant, if the modulation frequency @xmath0 is close to the intrinsic frequency of the soliton. for higher - order @xmath1-solitons with @xmath2 and @xmath3,   the response to an extremely weak perturbation is also resonant, if @xmath0 is close to the corresponding intrinsic frequency.   more importantly, a slightly stronger drive splits the @xmath4- or @xmath3-soliton, respectively, into a set of two or three moving fundamental solitons.   the dependence of the threshold perturbation amplitude, necessary for the splitting, on @xmath0 has a resonant character too.   amplitudes and velocities of the emerging fundamental solitons are accurately predicted, using exact and approximate conservation laws of the perturbed nls equation.   pacs numbers : 03.75.lm, 05.45.yv, 42.65.tg
we use the functional integral technique of edwards and lenard @xcite to solve the statistical mechanics of a one dimensional coulomb gas with boundary interactions leading to surface charging.   the theory examined is a one dimensional model for a soap film.   finite size effects and the phenomenon of charge regulation are studied.   we also discuss the pressure of disjunction for such a film. even in the absence of boundary potentials we find that the presence of a surface affects the physics in finite systems.   in general we find that in the presence of a boundary potential the long distance disjoining pressure is positive but may become negative at closer interplane separations.   this is in accordance with the attractive forces seen at close separations in colloidal and soap film experiments and with three dimensional calculations beyond mean field.   finally our exact results are compared with the predictions of the corresponding poisson - boltzmann theory which is often used in the context of colloidal and thin liquid film systems.    5 truemm * pacs : * 05.20 -y, 52.25.kn, 68.15.+e    5 truemm * key words :   * coulomb gas, functional integration, finite size effects, thin liquid films. 5 truemm damtp-97 - 61
many applications in science call for the numerical simulation of systems on manifolds with spherical topology. through use of integer spin   weighted spherical harmonics we present a method which allows for the implementation of arbitrary tensorial evolution equations.   our method combines two numerical techniques that were originally developed with different applications in mind.   the first is huffenberger and wandelt s spectral decomposition algorithm to perform the mapping from physical to spectral space.   the second is the application of luscombe and luban s method, to convert numerically divergent linear recursions into stable nonlinear recursions, to the calculation of reduced wigner d - functions.   we give a detailed discussion of the theory and numerical implementation of our algorithm.   the properties of our method are investigated by solving the scalar and vectorial advection equation on the sphere, as well as the @xmath0 maxwell equations on a deformed sphere.
we predict a clean signal at the large hadron collider ( @xmath0=14tev ) for a scenario where there is a top - like, charge @xmath1 vectorlike isosinglet fermion.   such a quark, via mixing with the standard model top, can undergo decays via both flavour - changing z - boson coupling and flavour - changing yukawa interactions.   we concentrate on the latter channel, and study the situation where, following its pair - production, the heavy quark pair gives rise to two tops and two higgs boson.   we show that the case where each higgs decays in the @xmath2 channel, there can be a rather distinct and background - free signal that can unveil the existence of the vectorlike isosinglet quark of this kind.   recapp - hri-2012 - 003     * a clean signal for a top - like isosinglet fermion at the large hadron collider * + aarti girdhar   and   biswarup mukhopadhyaya   + _ regional centre for accelerator - based particle physics _ + _ harish - chandra research institute _ + _ chatnaag road, jhunsi, allahabad, 211019,india _
we obtain two - dimensional exact analytic solutions for the structure of the hot accretion flows without wind.   we assume that the only non - zero component of the stress tensor is @xmath0.   furthermore we assume that the value of viscosity coefficient @xmath1 varies with @xmath2.   we find radially self - similar solutions and compare them with the numerical and the analytical solutions already studied in the literature. the no - wind solution obtained in this paper   may be applied to the nuclei of some cool - core clusters.       accretion - accretion discs -black hole physics - hydrodynamics.
in this work we propose a new orbital architecture for the two proposed circumbinary planets around the polar eclipsing binary hu aquarii.   we base the new two - planet, light - travel time model on the result of a monte carlo simulation driving a least - squares levenberg - marquardt minimisation algorithm on the observed eclipse egress times. our best - fitting model with @xmath0 resulted in high final eccentricities for the two companions leading to an unstable orbital configuration. from a large ensemble of initial guesses we examined the distribution of final eccentricities and semi - major axes for different @xmath1 parameter intervals and encountered qualitatively a second population of best - fitting parameters.   the main characteristic of this population is described by low - eccentric orbits favouring long - term orbital stability of the system.   we present our best - fitting model candidate for the proposed two - planet system and demonstrate orbital stability over one million years using numerical integrations.   binaries : close - binaries : eclipsing - stars : individual : hu aquarii - planetary systems : circumbinary planets
quantum manifestations of various properties of metallic thin films by quantum size effect ( qse ) have been studied intensively. here,   using first - principles calculations, we show quantum manifestation in dielectric properties of al(111 ) ultrathin films.   the qse on the dielectric function is revealed, which arises from size dependent contributions from both intraband and interband electronic transitions.   more importantly, the in - plane interband transitions in the films thinner than 15 monolayers are found to be smaller than the bulk counterpart in the energy range from 1.5  ev to 2.5  ev.   this indicates less energy loss with plasmonic material of al in the form of ultrathin film.   our findings may shed light on searching for low - loss plasmonic materials via quantum size effect.       .
trade - off between degree of joint measurability, sharpness and biasedness was known in the case of pairs of qubit observables. in the present work we generalised sharpness and biasedness measure for multilevel systems.   then a trade - off between amount of quantum mechanical ( qm ) violation of macrorealism ( mr ), sharpness and biasedness is established.   specifically we found minimum value of the sharpness parameter, above which qm violations of different necessary conditions of mr persist, decreases with increase of biasedness.   we also analysed the effect of biasedness parameter on magnitudes of qm violations of different necessary conditions of mr for multilevel spin systems.
we present observations of a solar quiet region obtained by the ground - based dutch open telescope ( dot ), and by instruments on the spacecraft soho and trace.   the observations were obtained during a coordinated observing campaign on october 2005.   the aim of this work is to present the rich diversity of fine - scale structures that are found at the network boundaries and their appearance in different instruments and different spectral lines that span the photosphere to the corona.   detailed studies of these structures are crucial to understanding their dynamics in different solar layers, as well as the role such structures play in the mass balance and heating of the solar atmosphere.
quantitatively assessing relationships between latent variables and observed variables is important for understanding and developing generative models and representation learning. in this paper, we propose latent - observed dissimilarity ( lod ) to evaluate the dissimilarity between the probabilistic characteristics of latent and observed variables.   we also define four essential types of generative models with different independence / conditional independence configurations.   experiments using tractable real - world data show that lod can effectively capture the differences between models and reflect the capability for higher layer learning.   they also show that the conditional independence of latent variables given observed variables contributes to improving the transmission of information and characteristics from lower layers to higher layers.
we investigate decay constants of @xmath0 and @xmath1-wave heavy - light mesons within the mock - meson approach.   numerical estimates are obtained using the relativistic quark model.   we also comment on recent calculations of heavy - light pseudo - scalar and vector decay constants.    6.1 in 8.5 in.25 in
motivated by the findings of logarithmic spreading of entanglement in a many - body localized system, we more closely examine the spreading of entanglement in the fully many - body localized phase, where all many - body eigenstates are localized. performing full diagonalizations of an xxz spin model with random longitudinal fields,   we identify two factors contributing to the spreading rate : the localization length ( @xmath0 ), which depends on the disorder strength, and the final value of entanglement per spin ( @xmath1 ), which primarily depends on the initial state.   we find that the entanglement entropy grows with time as @xmath2, providing support for the phenomenology of many - body localized systems recently proposed by huse and oganesyan .
we consider the interference of two photons with different colors in the context of a hong - ou - mandel experiment, in which single photons enter each of the input ports of a beam splitter, and exit in the same, albeit undetermined, output port.   such interference is possible if one uses an active ( energy - non - conserving ) beam splitter.   we find scenarios in which one `` red '' and one `` blue '' photon enter the beam splitter, and either two red or two blue photons exit, but never one of each color.   we show how the precise form of the active beam - splitter transformation determines in what way the spectral degrees of freedom of the input photons should be related to each other for perfect destructive interference of the different - color components in the output.   we discuss two examples of active beam splitters : one is a gedanken experiment involving a moving mirror and the other is a more realistic example involving four - wave mixing in an optical fiber.
in the present study, the effect of the pairing interaction and the isovector correlation between nucleons on the properties of the isobar analog resonances ( iar ) in @xmath0sb isotopes and the isospin admixture in @xmath1sn isotopes is investigated within the framework of the quasiparticle random phase approximation ( qrpa ).   the form of the interaction strength parameter is related to the shell model potential by restoring the isotopic invariance of the nuclear part of the total hamiltonian. in this respect,   the isospin admixtures in the @xmath1sn isotopes are calculated, and the dependence of the differential cross section and the volume integral @xmath2 for the sn(@xmath3he, t)sb reactions at e(@xmath3he)@xmath4 mev occurring by the excitation of iar on mass number a is examined.   our results show that the calculated value for the isospin mixing in the @xmath5sn isotope is in good agreement with colo et al.s estimates @xmath6, and the obtained values for the volume integral change within the error range of the value reported by fujiwara et al.   ( 53@xmath75 mev fm@xmath3 ).   moreover, it is concluded that although the differential cross section of the isobar analog resonance for the ( @xmath3he, t ) reactions is not sensitive to pairing correlations between nucleons, a considerable effect on the isospin admixtures in @xmath9 isotopes can be seen with the presence of these correlations.   = by -1
we analyze the non - local transport properties of a @xmath0-wave superconductor coupled to metallic electrodes at nanoscale distances.   we show that the non - local conductance exhibits an algebraical decay with distance rather than the exponential behavior which is found in conventional superconductors.   crossed andreev processes, associated with electronic entanglement, are favored for certain orientations of the symmetry axes of the superconductor with respect to the leads.   these properties would allow its experimental detection using present technologies.
collective low lying levels of light and medium xenon isotopes are deduced from the generalized bohr hamiltonian ( gbh ).   the microscopic seven functions entering into the gbh are built from a deformed mean field of the woods - saxon type.   theoretical spectra are found to be close to the ones of the experimental data taking into account that the calculations are completely microscopic, that is to say, without any fitting of parameters.
small - world networks ( swn ), obtained by randomly adding to a regular structure additional links ( al ), are of current interest. in this article we explore ( based on physical models ) a new variant of swn, in which the probability of realizing an al depends on the chemical distance between the connected sites.   we assume a power - law probability distribution and study random walkers on the network, focussing especially on their probability of being at the origin.   we connect the results to lvy flights, which follow from a mean field variant of our model.
the results of an observational campaign on the new @xmath0 scuti pulsator are reported.   the star was observed photometrically from august 26 to september 2, 2009 from the observatorio san pedro mrtir ( 0.84-m telescope, mexico ) and the observatorio del teide ( 0.80-m telescope, spain ).   an overall run of 53.8 h of useful data was collected from the two sites.   four oscillation frequencies for have been found above a 99% confidence level.   these results confirm the multiperiodic pulsation nature of the star suggested in previous observations with sparse data.   spectroscopic observations carried out in 2009 allowed us to derive its spectral type and luminosity class as well as to estimate its rotation rate. a simple comparison with models is performed.   stars : @xmath0 sct  techniques : photometric, spectroscopic  stars : oscillations  stars : individual :,,,.    97.30.dg, 97.10.ri, 97.10.vm, 97.10.zr, 97.10.sj
the concept of simulating a variant of qcd with sea quarks which interact with the gluon configuration only via global gluonic quantities like @xmath0 and @xmath1 is tested for the case of the massive 2-flavour schwinger model.   it is found to amount to an importance sampling method which generates at essentially the costs of a quenched run an ensemble in between a full and a quenched one, thus providing a competitive alternative to the quenched approximation.    * topologically unquenched qcd : prospects + from@xmath2an@xmath2explorative@xmath2study@xmath2in@xmath22-flavour - qed(2 ) *    * stephan drr * + _ paul scherrer institut, theory group _ + _ 5232 villigen psi, switzerland _   + stephan.duerr@psi.ch
multiview video has recently emerged as a means to improve user experience in novel multimedia services.   we propose a new stochastic model to characterize the traffic generated by a multiview video coding ( mvc ) variable bit rate source. to this aim  , we resort to a poisson hidden markov model ( p - hmm ), in which the first ( hidden ) layer represents the evolution of the video activity and the second layer represents the frame sizes of the multiple encoded views. we propose a method for estimating the model parameters in long mvc sequences. we then present extensive numerical simulations assessing the model s ability to produce traffic with realistic characteristics for a general class of mvc sequences.   we then extend our framework to network applications where we show that our model is able to accurately describe the sender and receiver buffers behavior in mvc transmission.   finally, we derive a model of user behavior for interactive view selection, which, in conjunction with our traffic model, is able to accurately predict actual network load in interactive multiview services.    digital video broadcasting, three dimensional tv, hidden markov models, multiview video.
in our previous study, we showed that the peculiar globular cluster ( gc ) m22 contains two distinct stellar populations, namely the @xmath0-@xmath1  and @xmath0-@xmath2  groups with different physical properties, having different chemical compositions, spatial distributions and kinematics.   we proposed that m22 is most likely formed via a merger of two gcs with heterogeneous metallicities in a dwarf galaxy environment and accreted later to our galaxy. in their recent study,   mucciarelli et al. claimed that m22 is a normal mono - metallic globular cluster without any perceptible metallicity spread among the two groups of stars, which challenges our results and those of others.   we devise new strategies for the local thermodynamic equilibrium ( lte ) abundance analysis of red giant branch ( rgb ) stars in gcs and show there exists a spread in the iron abundance distribution in m22.
a sample of very high resolution cosmological disk galaxy simulations is used to investigate the evolution of galaxy disk sizes back to redshift 1 within the @xmath0cdm cosmology.   artificial images in the rest frame @xmath1 band are generated, allowing for a measurement of disk scale lengths using surface brightness profiles as observations would, and avoiding any assumption that light must follow mass as previous models have assumed.   we demonstrate that these simulated disks are an excellent match to the observed magnitude   size relation for both local disks, and for disks at @xmath2=1 in the magnitude / mass range of overlap.   we disentangle the evolution seen in the population as a whole from the evolution of individual disk galaxies. in agreement with observations,   our simulated disks undergo roughly 1.5 magnitudes / arcsec@xmath3 of surface brightness dimming since @xmath2=1.   we find evidence that evolution in the magnitude  size plane varies by mass, such that galaxies with m@xmath4 @xmath5 10@xmath6 m@xmath7  undergo more evolution in size than luminosity, while dwarf galaxies tend to evolve potentially more in luminosity.   the disks grow in such a way as to stay on roughly the same stellar mass  size relation with time. finally, due to an evolving stellar mass  sfr relation, a galaxy at a given stellar mass ( or size ) at @xmath2=1 will reside in a more massive halo and have a higher sfr, and thus a higher luminosity, than a counterpart of the same stellar mass at @xmath2=0.
the floquet spectra of a class of driven su(2 ) systems have been shown to display butterfly patterns with multifractal properties.   the implication of such critical spectral behavior for the floquet eigenstate statistics is studied in this work. following the methodologies for understanding the fractal behavior of energy eigenstates of time - independent systems on the anderson transition point  , we analyze the distribution profile, the mean value, and the variance of the logarithm of the inverse participation ratio of the floquet eigenstates associated with multifractal floquet spectra.   the results show that the floquet eigenstates also display fractal behavior, but with features markedly different from those in time - independent anderson - transition models.   this motivated us to propose a new type of random unitary matrix ensemble, called  power - law random banded unitary matrix " ensemble, to illuminate the floquet eigenstate statistics of critical driven systems.   the results based on the proposed random matrix model are consistent with those obtained from our dynamical examples with or without time - reversal symmetry.
we study the correspondence between the non - trivial topological properties associated with the individual valleys of gapped bilayer graphene ( blg ), as a prototypical multi - valley system, and the gapless modes at its edges and other interfaces.   we find that the exact connection between the valley - specific hall conductivity and the number of gapless edge modes does not hold in general, but is dependent on the boundary conditions, even in the absence of intervalley coupling.   this non - universality is attributed to the absence of a well - defined topological invariant within a given valley of blg ; yet, a more general topological invariant may be defined in certain cases, which explains the distinction between the blg - vacuum and blg - blg interfaces.
this paper proposes real - time sequential convex programming ( rtscp ), a method for solving a sequence of nonlinear optimization problems depending on an online parameter.   we provide a contraction estimate for the proposed method and, as a byproduct, a new proof of the local convergence of sequential convex programming.   the approach is illustrated by an example where rtscp is applied to nonlinear model predictive control.
we study the spectrum of vibrational modes in metal nanoparticles with a dielectric core.   vibrational modes are excited by the rapid heating of the particle lattice that takes place after laser excitation, and can be monitored by means of pump - probe spectroscopy as coherent oscillations of transient optical spectra. in nanoshells,   the presence of two metal surfaces results in a substantially different energy spectrum of acoustic vibrations than for solid particles.   we calculated the energy spectrum as well as the damping of nanoshell vibrational modes.   the oscillator strength of fundamental breathing mode is larger than that in solid nanoparticles. at the same time, in very thin nanoshells, the fundamental mode is overdamped due to instantaneous energy transfer to the surrounding medium.
we study the evolution of bubble spacetimes in vacuum and electrovac scenarios by numerical means.   we find strong evidence against the formation of naked singularities in ( i ) scenarios with negative masses displaying initially collapsing conditions and ( ii ) scenarios with negative masses displaying initially expanding conditions, previously reported to give rise to such singularities.   additionally, we show that the presence of strong gauge fields implies that an initially collapsing bubble bounces back and expands. by fine - tuning the strength of the gauge field   we find that the solution approaches a static bubble solution.
we study the dynamics of two gray solitons in a bose - einstein condensate confined by a toroidal trap with a tight confinement in the radial direction.   gross - pitaevskii simulations show that solitons can be long living objects passing through many collisional processes.   we have observed quite different behaviors depending on the soliton velocity.   very slow solitons, obtained by perturbing the stationary solitonic profile, move with a constant angular velocity until they collide elastically and move in the opposite direction without showing any sign of lowering their energy. in this case   the density notches are always well separated and the fronts are sharp and straight. faster solitons present vortices around the notches, which play a central role during the collisions.   we have found that in these processes the solitons lose energy, as the outgoing velocity turns out to be larger than the incoming one. to study the dynamics, we model the gray soliton state with a free parameter that is related to the soliton velocity.   we further analyze the energy, soliton velocity and turning points in terms of such a free parameter, finding that the main features are in accordance with the infinite one - dimensional system.
we propose a simple unifying structure for the inner regions of quasars and agn.   this empirically derived model links together the bals, the narrow uv / x - ray ionized absorbers, the belr, and the compton scattering / fluorescing regions into a single structure.   the model also suggests an origin for the large - scale bi - conical outflows. some other potential implications of this structure are discussed.   galaxies : active ; quasars : general ; quasars : absorption lines
we set up a left ring of fractions over a certain ring of boundary problems for linear ordinary differential equations.   the fraction ring acts naturally on a new module of generalized functions.   the latter includes an isomorphic copy of the differential algebra underlying the given ring of boundary problems.   our methodology employs noncommutative localization in the theory of integro - differential algebras and operators.   the resulting structure allows to build a symbolic calculus in the style of heaviside and mikusiski, but with the added benefit of incorporating boundary conditions where the traditional calculi allow only initial conditions.
we calculate all gauge invariant barr - zee type contributions to fermionic electric dipole moments ( edms ) in the two - higgs doublet models ( 2hdm ) with softly broken @xmath0 symmetry.   we start by studying the tensor structure of @xmath1 part in the barr - zee diagrams, and we calculate the effective couplings in a gauge invariant way by using the pinch technique.   then we calculate all barr - zee diagrams relevant for electron and neutron edms.   we make bounds on the parameter space in type - i, type - ii, type - x, and type - y 2hdms.   the electron and neutron edms are complementary to each other in discrimination of the 2hdms.   type - ii and type - x 2hdms are strongly constrained by recent acme experiment s result, and future experiments of electron and neutron edms may search @xmath2(10 ) tev physics.   kek  th1682 + ut1338 + ipmu130209 +   november, 2013 +.75 in     * gauge invariant barr - zee type contributions + to fermionic edms + in the two - higgs doublet models *   .6 in     * * tomohiro abe**@xmath3, * * junji hisano**@xmath4, + * * teppei kitahara**@xmath5, and * * kohsaku tobioka**@xmath6 0.3 in    @xmath3_theory group, kek, tsukuba, 305 - 0801, japan _ 0.1 in @xmath7_department of physics, nagoya university, nagoya 464 - 8602, japan _ 0.1 in
models of galaxy formation invoke the major merger of gas - rich progenitor galaxies as the trigger for significant phases of black hole growth and the associated feedback that suppresses star formation to create red spheroidal remnants.   however, the observational evidence for the connection between mergers and active galactic nucleus ( agn ) phases is not clear.   we analyze a sample of low - mass early - type galaxies known to be in the process of migrating from the blue cloud to the red sequence via an agn phase in the green valley. using deeper imaging from sdss stripe 82  , we show that the fraction of objects with major morphological disturbances is high during the early starburst phase, but declines rapidly to the background level seen in quiescent early - type galaxies by the time of substantial agn radiation several hundred myr after the starburst.   this observation empirically links the agn activity in low - redshift early - type galaxies to a significant merger event in the recent past.   the large time delay between the merger - driven starburst and the peak of agn activity allows for the merger features to decay to the background and hence may explain the weak link between merger features and agn activity in the literature.
we examine the possibility of distinguishing a supersymmetric gluino from a kaluza - klein gluon of universal extra dimensions ( ued ) at the large hadron collider ( lhc ).   we focus on the case when all kinematically allowed tree - level decays of this particle are 3-body decays into two jets and a massive daughter ( typically weak gaugino or kaluza - klein weak gauge boson ).   we show that the shapes of the dijet invariant mass distributions differ significantly in the two models, as long as the mass of the decaying particle @xmath0 is substantially larger than the mass of the massive daughter @xmath1.   we present a simple analysis estimating the number of events needed to distinguish between the two models under idealized conditions.   for example, for @xmath2, we find the required number of events to be of order several thousand, which should be available at the lhc within a few years.   this conclusion is confirmed by a parton level monte carlo study which includes the effects of experimental cuts and the combinatoric background.  .5 cm    * testing gluino spin with three - body decays *.2 cm    * csaba cski, johannes heinonen and maxim perelstein *   +    _ institute for high energy phenomenology + newman laboratory of elementary particle physics, + cornell university, ithaca, ny 14853, usa _   +    0.3truecm
( 0,0 ) ( 120,88 )    the time projection chamber ( tpc ) for the international linear collider will need to measure about 200 track points with a resolution close to 100 @xmath0 m.   a micro pattern gas detector ( mpgd ) readout tpc could achieve the desired resolution with existing techniques using sub - millimeter width pads at the expense of a large increase in the detector cost and complexity.   we have recently applied a new mpgd readout concept of charge dispersion to a prototype gem - tpc and demonstrated the feasibility of achieving good resolution with pads similar in width to the ones used for the proportional wire tpc.   the charge dispersion studies were repeated with a micromegas tpc amplification stage.   we present here our first results on the micromegas - tpc resolution with charge dispersion.   the tpc resolution with the micromegas readout is compared to our earlier gem results and to the resolution expected from electron statistics and transverse diffusion in a gaseous tpc.
gev gamma - ray emission from two gamma - ray binary candidates, hess j0632 + 057 and agl j2241 + 4454, which were recently reported by h.e.s.s. and agile, respectively,   have been searched for using the fermi - lat archival dataset.   spatial and temporal distribution of gamma - ray events are studied, but there was no evidence for gev gamma - ray signal from either sources.
we present measurements of the clustering of hot and cold patches in the microwave background sky as measured from the _   _ w__ilkinson _ _ m__icrowave _ _ a__nisotropy _ _ p__robe ( wmap ) five - year data.   these measurements are compared with theoretical predictions which assume that the cosmological signal obeys gaussian statistics.   we find significant differences from the simplest gaussian - based prediction.   however, the measurements are sensitive to the fact that the noise is spatially inhomogeneous ( e.g., because different parts of the sky were observed for different lengths of time ).   we show how to account for this spatial inhomogeneity when making predictions.   differences from the gaussian - based expectation remain even after this more careful accounting of the noise.   in particular, we note that hot and cold pixels cluster differently within the same temperature thresholds at few - degree scales.   while these findings may indicate primordial non - gaussianity, we discuss other plausible explanations for these discrepancies.   in addition, we find some deviations from gaussianity at sub - degree scales, especially in the w band, whose origin may be associated with extragalactic dust emission.       methods : statistical  methods : data analysis  cosmology : cosmic microwave background, correlations  cosmology : observations.
we present an exploratory survey of the central regions of the nearby spiral galaxies dwingeloo  1 and dwingeloo  2 made in the co  j=21 line at 230 ghz using the james clerk maxwell telescope. in dwingeloo  1, which is probably the nearest grand  design barred spiral, the co emission was sampled along a cross with its major axis aligned with the bar.   the co emission is an order of magnitude weaker ( peak @xmath0 70 ) than in its neighbours ic  342 and maffei  2 and appears to be confined to the nucleus, bar, and spiral arms. in dwingeloo  2, a small system quite likely to be a companion of dw1, a 3-sigma upper limit of 40@xmath1 for the co  j=21 emission from the nucleus was obtained.   2cm^-2 3cm^-3 2pc^-2 34sc^34s 3cs^13cs _a&a _
we propose a dynamical boolean network ( dbn ), which is a virtual boolean network ( vbn ) whose set of states is fixed but whose transition matrix can change from one discrete time step to another.   the transition matrix @xmath0 of our dbn for time step  @xmath1 is of the form @xmath2, where @xmath3 is a transition matrix ( of a vbn ) defined at time step  @xmath1 in the course of the construction of our dbn and @xmath4 is the matrix representation of some randomly chosen permutation @xmath5 of the states of our dbn. for each of several classes of such permutations  , we carried out a number of simulations of a dbn with two nodes ; each of our simulations consisted of 1,000 trials of 10,000 time steps each. in one of our simulations,   only six of the 16 possible single - node transition rules for a vbn with two nodes were visited a total of 300,000 times ( over all 1,000 trials ). in that simulation, linearity appears to play a significant role in that three of those six single - node transition rules are transition rules of a linear virtual boolean network ( lvbn ) ; the other three are the negations of the first three.   we also discuss the notions of a probabilistic boolean network and a hidden markov model  in both cases, in the context of using an arbitrary ( though not necessarily one - to - one ) function to label the states of a vbn.   note    internal measurement ; boolean network ; probabilistic boolean network ; hidden markov model ; linearity
due to the no - cloning theorem, the unknown quantum state can only be cloned approximately or exactly with some probability.   there are two types of cloners : universal and state - dependent cloner.   the optimal universal cloner has been found and could be viewed as a special state - dependent quantum cloner which has no information about the states. in this paper, we investigate the state - dependent cloning when the state - set contains more than two states.   we get some bounds of the global fidelity for these processes.   this method is not dependent on the number of the states contained in the state - set.   it is also independent of the numbers of copying.   pacs number(s ) : 03.67.-a, 03.65.ta, 89.70.+c
as part of our ongoing effort to investigate transit timing variations ( ttvs ) of known exoplanets, we monitored transits of the four exoplanets hat - p-18b, hat - p-19b, hat - p-27b / wasp-40b and wasp-21b.   all of them are suspected to show ttvs due to the known properties of their host systems based on the respective discovery papers. during the past three years   42 transit observations were carried out, mostly using telescopes of the young exoplanet transit initiative.   the analyses are used to refine the systems orbital parameters. in all cases we found no hints for significant ttvs, or changes in the system parameters inclination, fractional stellar radius and planet to star radius ratio and   thus could confirm the already published results.       planets and satellites : individual : hat - p-18b, hat - p-19b, hat - p-27b / wasp-40b, wasp-21b
the bepposax high energy large area survey ( hellas ) has surveyed several tens of square degrees of the sky in the 510 kev band down to a flux of about @xmath0.   the source surface density of 16.9@xmath16.4 deg@xmath2 at the survey limit corresponds to a resolved fraction of the 510 kev x  ray background ( xrb ) of the order of 2030 %.   the extrapolation of the hellas logn   logs towards fainter fluxes with an euclidean slope is consistent with the first xmm_newton _ measurements, in the same energy band, which are a factor 20 more sensitive.   the source counts in the hardest band so far surveyed by x   ray satellites are used to constrain xrb models.   it is shown that in order to reproduce the 510 kev counts over the range of fluxes covered by bepposax and xmm_newton _ a large fraction of highly absorbed ( log@xmath3 = 2324 cm@xmath2 ), luminous ( @xmath5 erg s@xmath6 ) agn is needed.   a sizeable number of more heavily obscured, compton thick, objects can not be ruled out but it is not required by the present data. the model predicts an absorption distribution consistent with that found from the hardness ratios analysis of the so far identified hellas sources.   interestingly enough, there is evidence of a decoupling between x  ray absorption and optical reddening indicators especially at high redshifts / luminosities where several broad line quasars show hardness ratios typical of absorbed power law models with log@xmath3=2224 cm@xmath2.   = -0.5 in    x  ray : background  galaxies  agn
we present the mass distribution for all s / n@xmath015 pure da white dwarfs detected in the sloan digital sky survey up to data release 12, fitted with koester models for ml2/@xmath1, and with @xmath2  k, and for dbs with s / n@xmath010, fitted with ml2/@xmath3, for @xmath4  k. these mass distributions are for @xmath5 stars, i.e., excluding the extremely low mass white dwarfs.   we also present the mass distributions corrected by volume with the @xmath6 approach, for stars brighter than g=19.   both distributions have a maximum at @xmath7 but very distinct shapes. from the estimated z - distances,   we deduce a disk scale height of 300 pc.   we also present 10 probable halo white dwarfs, from their galactic u, v, w velocities.
we propose a hodge field theory construction that captures algebraic properties of the reduction of zwiebach invariants to gromov - witten invariants.   it generalizes the barannikov - kontsevich construction to the case of higher genera correlators with gravitational descendants.   we prove the main theorem stating that algebraically defined hodge field theory correlators satisfy all tautological relations. from this perspective   the statement that barannikov - kontsevich construction provides a solution of the wdvv equation looks as the simplest particular case of our theorem.   also it generalizes the particular cases of other low - genera tautological relations proven in our earlier works ; we replace the old technical proofs by a novel conceptual proof.
on the basis of the kinetic equation with selfconsistent relativistic mean fields acting on baryons and antibaryons, we study dynamical response of the nucleus to an antiproton implanted in its interior. by solving numerically the time - dependent vlasov equation, we show that the compressed state is formed on a rather short time scale of about @xmath0 fm / c.   this justifies the assumption, that the antiproton annihilation may happen in the compressed nuclear environment.   the evolution of the nucleus after antiproton annihilation is described by the same kinetic equation including collision terms.   we show, that nucleon kinetic energy spectra and the total invariant mass distributions of produced mesons are quite sensitive observables to the antiproton annihilation in the compressed nucleus.
we discuss the spectrum of var c in m33 obtained just before the onset of its current brightening and recent spectra during its present `` eruption '' or optically thick wind stage.   these spectra illustrate the typical lbv transition in apparent spectral type or temperature that characterizes the classical lbv or s dor - type variability.   lbvs are known to have slow, dense winds during their maximum phase.   interestingly, _   var c had a slow wind even during its hot, quiescent stage in comparison with the normal hot supergiants with similar temperatures.   its outflow or wind speeds also show very little change between these two states. _
quantum squeezing in mechanical systems is not only a key signature of macroscopic quantum effects, but can also be utilized to advance the metrology of weak forces. here   we show that strong mechanical squeezing in the steady state can be generated in an optomechanical system with mechanical nonlinearity and red - detuned monochromatic driving on the cavity mode.   the squeezing is achieved as the joint effect of nonlinearity - induced parametric amplification and cavity cooling, and is robust against thermal fluctuations of the mechanical mode.   we also show that the mechanical squeezing can be detected via an ancilla cavity mode.
in order to assess the performance of liquid xenon detectors for use in positron emission tomography we studied the scintillation light and ionization charge produced by 511  kev photons in a small prototype detector.   scintillation light was detected with large area avalanche photodiodes while ionization electrons were collected on an anode instrumented with low noise electronics after drifting up to 3  cm.   operational conditions were studied as a function of the electric field.   energy resolutions of @xmath0% ( fwhm ) were achieved by combining the scintillation light and ionization charge signals. the relationship between scintillation light and ionization signals was investigated.   an analysis of the sources of fluctuations was performed in order to optimize future detector designs.   liquid xenon, pet, medical imaging, tpc 29.40.gx, 87.57.-s, 87.57.uk
the unusual band structure of carbon nanotubes ( cns ) results in their remarkable magnetic properties.   the application of magnetic field parallel to the tube axis can change the conducting properties of the cn from metallic to semiconducting and vice versa. apart from that   * b * induces ( via the bohm - aharonov effect ) orbital magnetic moments @xmath0 in the nanotube.   these moments are studied both in pure and hole- or electron - doped cns, isolated or in a circuit.   remarkably, @xmath0 in pure cns depends uniquely on their original conducting properties, length, and temperature but it does not depend on the nanotube radius or the particular chirality. in doped   nanotubes the magnetic moments can be strongly altered and depend on the radius and chirality.   temperature can even change their character from diamagnetic at low @xmath1 to paramagnetic at high @xmath1. a full electron - hole symmetry in doped tubes is also revealed.
the heidelberg dark matter search experiment ( hdms ) is a new ionization germanium experiment in a special design.   two concentric ge crystals are housed by one cryostat system, the outer detector acting as an effective shield against multiple scattered photons for the inner crystal, which is the actual dark matter target.   we present first results after successfully running the prototype detector for a period of about 15 months in the gran sasso underground laboratory.   we analyze the results in terms of limits on wimp - nucleon cross sections and present the status of the full scale experiment, which will be installed in gran sasso in the course of this year.
we analyzed @xmath0 and @xmath1 light curves of 19 well observed magnetic cp stars selected from the _ on - line database of photometric observations of mcp stars _ of which light curves in all the five colours were similar.   we assumed that among these photometrically simply behaving ( psb ) stars could be found such ones which have a single photometric spot.   the insight into such simple situations would help us to comprehend more complicated cases.   light curves of the 19 psb mcp stars proved to be generally nearly symmetric but surprisingly diverse.   the analysis shows that only in the case of hd110956b, hd188041, and perhaps hd193722 we are able to explain their photometric behaviour by a simple one - spot model.   consequently, occurrence of more than one photometric spot on an mcp star is typical.
assume a set of objects is given with information about their bilateral relationships, allowing for incomplete and multiple comparisons as well as different preference intensities.   an axiomatic approach is applied for the problem of ranking the objects.   consistency requires the preservation of relative ranking if two sets of such preferences are aggregated.   self - consistency assigns the same rank for objects with the same performance, furthermore, an object should be ranked strictly higher if it shows an obviously better performance than another.   it is revealed that these two properties can not be satisfied simultaneously.   the impossibility holds under various restrictions on the domain.   however, a positive result emerges if only the aggregation of ranking problems with the same comparison structure is allowed, for example, we have two round - robin tournaments.
agile ( astro - rivelatore gamma ad immagini leggero ) is a small scientific mission of the italian space agency ( asi ) with a science program open to the national and international community.   its main goal is to develop and operate a scientific satellite devoted to gamma - ray ( 30mev@xmath050gev ) and hard x - ray ( 10@xmath040kev ) astrophysics during the years 2005@xmath02007.   asi plans to handle agile data through the asi science data center in collaboration with the agile team.
sn2006 oz is a super - luminous supernova with a mysterious bright precursor that has resisted explanation in standard models.   however, such a precursor has been predicted in the dual - shock quark nova ( dsqn ) model of super - luminous supernovae  the precursor is the sn event while the main light curve of the slsn is powered by the quark - nova ( qn ; explosive transition of the neutron star to a quark star ). as the sn is fading,   the qn re - energizes the sn ejecta, producing a  double - humped " light curve. in this paper  , we show the dsqn model successfully reproduces the observed light curve of sn2006 oz.
of the approximately 400 known galactic classical novae, only ten of them, the recurrent novae, have been seen to erupt more than once.   at least eight of these recurrents are known to harbor evolved secondary stars, rather than the main sequence secondaries typical in classical novae. in this paper  , we propose a new nova classification system, based solely on the evolutionary state of the secondary, and not ( like the current schemes ) based on the properties of the outbursts.   using archival optical and near - infrared photometric observations of a sample of thirty eight quiescent galactic novae we show that the evolutionary state of the secondary star in a quiescent system can predicted and several objects are identified for follow - up observations ; ci  aql, v2487  oph, di  lac and eu  sct.
we provide two mathematical descriptions of spekkens s toy qubit theory, an inductively one in terms of a small set of generators, as well as an explicit closed form description.   it is a subcategory * mspek * of the category of finite sets, relations and the cartesian product.   states of maximal knowledge form a subcategory * spek*. this establishes the consistency of the toy theory, which has previously only been constructed for at most four systems.   our model also shows that the theory is closed under both parallel and sequential composition of operations (= symmetric monoidal structure ), that it obeys map - state duality (= compact closure ), and that states and effects are in bijective correspondence (= dagger structure ). from the perspective of categorical quantum mechanics,   this provides an interesting alternative model which enables us to describe many quantum phenomena in a discrete manner, and to which mathematical concepts such as basis structures, and complementarity thereof, still apply.   hence, the framework of categorical quantum mechanics has delivered on its promise to encompass theories other than quantum theory.
we have performed unpolarized and polarized neutron diffraction experiments on monodisperse 8 nm and 13 nm antiferromagnetic mno nanoparticles. for the 8 nm sample, the antiferromagnetic transition temperature @xmath0 ( 114 k )   is suppressed compared to the bulk material ( 119 k ) while for the 13 nm sample @xmath0 ( 120 k ) is comparable to the bulk.   the neutron diffraction data of the nanoparticles is well described using the bulk mno magnetic structure but with a substantially reduced average magnetic moment of 4.2@xmath10.3 @xmath2/mn for the 8 nm sample and 3.9@xmath10.2 @xmath2/mn for the 13 nm sample.   an analysis of the polarized neutron data on both samples shows that in an individual mno nanoparticle about 80@xmath3 of mn ions order.   these results can be explained by a structure in which the monodisperse nanoparticles studied here have a core that behaves similar to the bulk with a surface layer which does not contribute significantly to the magnetic order.
we review different computation methods for the renormalised energy momentum tensor of a quantised scalar field in an einstein static universe. for the extensively studied conformally   coupled case we check their equivalence ; for different couplings we discuss violation of different energy conditions. in particular, there is a family of masses and couplings which violate the weak and strong energy conditions but do not lead to spacelike propagation. amongst these cases   is that of a minimally coupled massless scalar field with no potential.   we also point out a particular coupling for which a massless scalar field has vanishing renormalised energy momentum tensor.   we discuss the backreaction problem and in particular the possibility that this casimir energy could both source a short inflationary epoch and avoid the big bang singularity through a bounce.
the statistics of records in sequences of independent, identically distributed random variables is a classic subject of study.   one of the earliest results concerns the stochastic independence of record events.   recently, records statistics beyond the case of i.i.d.   random variables have received much attention, but the question of independence of record events has not been addressed systematically. in this paper, we study this question in detail for the case of independent, non - identically distributed random variables, specifically, for random variables with a linearly moving mean.   we find a rich pattern of positive and negative correlations, and show how their asymptotics is determined by the universality classes of extreme value statistics.
in this work we describe our implementation of a thermodynamic energy equation into the global corona model of the space weather modeling framework ( swmf ), and its development into the new lower corona ( lc ) model.   this work includes the integration of the additional energy transport terms of coronal heating, electron heat conduction, and optically thin radiative cooling into the governing magnetohydrodynamic ( mhd ) energy equation.   we examine two different boundary conditions using this model ; one set in the upper transition region ( the radiative energy balance model ), as well as a uniform chromospheric condition where the transition region can be modeled in its entirety. via observation synthesis from model results and the subsequent comparison to full sun extreme ultraviolet ( euv ) and soft x - ray observations of carrington rotation ( cr ) 1913 centered on aug 27, 1996,   we demonstrate the need for these additional considerations when using global mhd models to describe the unique conditions in the low corona. through multiple simulations we examine ability of the lc model to asses and discriminate between coronal heating models, and   find that a relative simple empirical heating model is adequate in reproducing structures observed in the low corona.   we show that the interplay between coronal heating and electron heat conduction provides significant feedback onto the 3d magnetic topology in the low corona as compared to a potential field extrapolation, and that this feedback is largely dependent on the amount of mechanical energy introduced into the corona.
we provide a general and tractable framework under which all multiple yield curve modeling approaches based on affine processes, be it short rate, libor market, or hjm modeling, can be consolidated.   we model a numraire process and multiplicative spreads between libor rates and simply compounded ois rates as functions of an underlying affine process. besides allowing for ordered spreads and an exact fit to the initially observed term structures, this general framework leads to tractable valuation formulas for caplets and swaptions and embeds all existing multi - curve affine models.   the proposed approach also gives rise to new developments, such as a short rate type model driven by a wishart process, for which we derive a closed - form pricing formula for caplets.   the empirical performance of two specifications of our framework is illustrated by calibration to market data.
we normalize the combinatorial laplacian of a graph by the degree sum, look at its eigenvalues as a probability distribution and then study its shannon entropy.   equivalently, we represent a graph with a quantum mechanical state and study its von neumann entropy. at the graph - theoretic level  , this quantity may be interpreted as a measure of regularity ; it tends to be larger in relation to the number of connected components, long paths and nontrivial symmetries.   when the set of vertices is asymptotically large, we prove that regular graphs and the complete graph have equal entropy, and specifically it turns out to be maximum. on the other hand, when the number of edges is fixed, graphs with large cliques appear to minimize the entropy.
the canonical aharonov - bohm effect is usually studied with time - independent potentials. in this work,   we investigate the aharonov - bohm phase acquired by a charged particle moving in _ time - dependent _ potentials.   in particular, we focus on the case of a charged particle moving in the time varying field of a plane electromagnetic wave.   we work out the aharonov - bohm phase using both the potential ( _ i.e. _ @xmath0 ) and field ( _ i.e. _ @xmath1 ) forms of the aharanov - bohm phase.   we give conditions in terms of the parameters of the system ( frequency of the electromagnetic wave, the size of the space - time loop, amplitude of the electromagnetic wave ) under which the time varying aharonov - bohm effect could be observed.
in this paper, we report on new high - precision absolute distance measurements performed with frequency scanned interferometry using a pair of single - mode optical fibers.   absolute distances were determined by counting the interference fringes produced while scanning the frequencies of the two chopped lasers.   high - finesse fabry - perot interferometers were used to determine frequency changes during scanning.   dual lasers with oppositely scanning directions, combined with a multi - distance - measurement technique previously reported, were used to cancel drift errors and to suppress vibration effects and interference fringe uncertainties. under realistic conditions, a precision   about 0.2 microns was achieved for a distance of 0.41 meters.
we present very large array observations at @xmath0 cm of the nearby young star tw  hya that show the emission is constant in time over weeks, months and years, and spatially resolved with peak brightness temperature @xmath1  k at @xmath2 ( 15 au ) resolution.   these features are naturally explained if the emission mechanism at this wavelength is thermal emission from dust particles in the disk surrounding the star. to account quantitatively for the observations,   we construct a self - consistent accretion disk model that incorporates a population of centimeter size particles that matches the long wavelength spectrum and spatial distribution  . a substantial mass fraction of orbiting particles in the tw  hya disk must have agglomerated to centimeter size.   these data provide the first clear indication that dust emission from protoplanetary disks may be observed at centimeter wavelengths, and that changes in the spectral slope of the dust emission may be detected, providing constraints on dust evolution and the planet formation process.
in this work, we present a topological characterization of superconductivity in a prototype electron fractionalization model for doped mott insulators. in this model,   spinons and holons are coupled via the mutual chern - simons gauge fields.   we obtain a low - lying effective description of the collective current fluctuations by integrating out the matter fields, which replaces the conventional ginzburg - landau action to describe the generalized rigidity of superconductivity.   the superconducting phase coherence is essentially characterized by a topological order parameter related to a gaussian linking number, and an experiment is proposed to probe this topological property.   we further show that a gauge - neutral fermionic mode can naturally emerge in this model, which behaves like a bogoliubov quasiparticle.
we investigate the problem of teleporting unknown qudit states via pure quantum channels with nonmaximal schmidt rank.   this process is mapped to the problem of discriminating among nonorthogonal symmetric states which are linearly dependent and equally likely.   it is shown that by applying an optimized maximum - confidence ( mc ) measurement for accomplishing this task, one reaches the maximum possible teleportation fidelity after a conclusive event in the discrimination process, which in turn occurs with the maximum success probability. in this case  , such fidelity depends only on the schmidt rank of the channel and it is larger than the optimal one achieved, deterministically, by the standard teleportation protocol.   furthermore, we show that there are quantum channels for which it is possible to apply a @xmath0-stage sequential mc measurement in the discrimination process such that a conclusive event at any stage leads to a teleportation fidelity above the aforementioned optimal one and, consequently, increases the overall success probability of teleportation with a fidelity above this limit.
we consider the dynamics of a reaction - diffusion system on a multigraph.   the species share the same set of nodes but can access different links to explore the embedding spatial support. by acting on the topology of the networks we can control the ability of the system to self - organise in macroscopic patterns, emerging as a symmetry breaking instability of an homogeneous fixed point.   two different cases study are considered : on the one side, we produce a global modification of the networks, starting from the limiting setting where species are hosted on the same graph. on the other  , we consider the effect of inserting just one additional single link to differentiate the two graphs. in both cases,   patterns can be generated or destroyed, as follows the imposed, small, topological perturbation.   approximate analytical formulae allows to grasp the essence of the phenomenon and can potentially inspire innovative control strategies to shape the macroscopic dynamics on multigraph networks.
we examine the composition of matter as it flows away from gamma ray burst accretion disks, in order to determine what sort of nucleosynthesis may occur.   since there is a large flux of neutrinos leaving the surface of the disk, the electron fraction of the outflowing material will change due to charged current neutrino interactions.   we calculate the electron fraction in the wind using detailed neutrino fluxes from every point on the disk and study a range of trajectories and outflow conditions for several different accretion disk models.   we find that low electron fractions, conducive to making @xmath0-process elements, only appear in outflows from disks with high accretion rates that have a significant region both of trapped neutrinos and antineutrinos.   disks with lower accretion rates that have only a significant region of trapped neutrinos can have outflows with very high electron fractions, whereas the lowest accretion rate disks with little trapping have outflow electrons fractions of closer to one half.
we study in the bfkl approach the total hadronic cross section for the collision of two virtual photons for energies in the range of lep2 and of future linear colliders.   the bfkl resummation is done at the next - to - leading order in the bfkl green s function ; photon impact factors are taken instead at the leading order, but with the inclusion of the subleading terms required by invariance under changes of the renormalization scale and of the bfkl scale @xmath0.   we compare our results with previous estimations based on a similar kind of approximation.     address=_dipartimento di fisica, universit della calabria + and istituto nazionale di fisica nucleare, gruppo collegato di cosenza + i-87036 arcavacata di rende, cosenza, italy _     address = sobolev institute of mathematics and novosibirsk state university, + 630090 novosibirsk, russia     address=_dipartimento di fisica, universit della calabria + and istituto nazionale di fisica nucleare, gruppo collegato di cosenza + i-87036 arcavacata di rende, cosenza, italy _
schwope et al ( 1997 ) suggested that the newly discovered polar rx j2115 - 5840 is a near - synchronous system.   we have obtained circular polarisation observations of rx j2115 - 5840 which show that the spin and orbital periods differ by 1.2%.   we find the first direct evidence of ` pole - switching'in a near - synchronous polar.   further our data requires that the accretion flow must be directed onto the same magnetic field line at all spin - orbit beat phases implying that at some phases the flow must follow a path around the white dwarf before accreting.
we compute bulk properties of heisenberg spin-1/2 ladders using rayleigh - schrdinger perturbation theory in the rung and plaquette bases.   we formulate a method to extract high - order perturbative coefficients in the bulk limit from solutions for relatively small finite clusters.   for example, a perturbative calculation for an isotropic @xmath0 ladder yields an eleventh - order estimate of the ground - state energy per site that is within 0.02% of the density - matrix - renormalization - group ( dmrg ) value.   moreover, the method also enables a reliable estimate of the radius of convergence of the perturbative expansion.   we find that for the rung basis the radius of convergence is @xmath1, with @xmath2 defining the ratio between the coupling along the chain relative to the coupling across the chain.   in contrast, for the plaquette basis we estimate a radius of convergence of @xmath3.   thus, we conclude that the plaquette basis offers the only currently available perturbative approach which can provide a reliable treatment of the physically interesting case of isotropic @xmath4 spin ladders.   we illustrate our methods by computing perturbative coefficients for the ground - state energy per site, the gap, and the one - magnon dispersion relation.
the electroweak phase transition and the sphaleron decoupling condition in the minimal supersymmetric standard model are revisited taking the latest experimental data into account. the light higgs boson scenario and the ordinary decoupling limit which are classified by the relative size between the @xmath0-odd higgs boson mass and @xmath1 boson mass   are considered within the context of electroweak baryogenesis.   we investigate @xmath2 at not only the critical temperature at which the effective potential has two degenerate minima but also the nucleation temperature of the critical bubbles, where @xmath3 is a vacuum expectation value of the higgs boson and @xmath4 denotes a temperature.   it is found that @xmath2 at the nucleation temperature can be enhanced by about 10% compared to that at the critical temperature.   we also evaluate the sphaleron decoupling condition including the zero mode factors of the fluctuations around sphaleron.   it is observed that the sphaleron decoupling condition at the nucleation temperature is given by @xmath5 for the typical parameter sets. in any phenomenologically allowed region, @xmath2 at both the critical and nucleation temperatures can not be large enough to satisfy such a sphaleron decoupling condition.
considering neutrinos as time - like leptons one may estimate the three - body decay probability of muon neutrinos in long base - line accelerator experiments. in the extreme assumption of time - space symmetry   the absolute value of the transcendent mass of a muon neutrino is equal to the rest mass of its bradyon partner which is, however, strongly suppressed in measurements using the weak interaction.   this decay, neglecting small oscillations or other effects, leads to a strong dependence of the effect on the base - line distance. as a result  , few hundred kilometre long baseline experiments might hardly see muon - like events.   total rates of electron - like events from three - body decay are calculated for k2k, minos and icarus.   shorter base - line experiments able to see clearly the effect of muon neutrino decay are very promissing component of long base - line projects.   +    to be submitted to the workshop on `` neutrino oscillations and their origin '', fuji - yoshida, japan, 11 - 13 february 2000.   pnumwidth2em    specialpagefalse oddheadv.v.thuan at al.neutrino decay...   evenheadoddhead oddfoot@font@page=1 evenfootoddfoot    2
we address the question of the relations between the black hole s mass, the accretion rate, the bolometric luminosity, the optical luminosity and the size of the broad line region ( blr ) in active galactic nuclei, using recent observational data obtained from monitoring campaigns.   we show that a standard accretion disc can not account for the observed optical luminosity, unless it radiates at super - eddington rates.   this implies the existence of another, dominant emission mechanism in the optical range, or a non standard disc ( non stationary, adaf and/or strong outflows ).   narrow line seyfert 1 galaxies ( nls1s ) are most extreme in this context : they have larger bolometric to eddington luminosity ratios than broad line seyfert 1 ( bls1s ), and most likely a larger  non disc " component in the optical range. from realistic simulations of self - gravitating @xmath0-discs  , we have systematically localized the gravitationally unstable disc and shown that, given uncertainties on both the model and observations, it coincides quite well with the size of the blr.   we therefore suggest that the gravitationally unstable disc is the source which releases blr clouds in the medium.   however the influence of the ionization parameter is also required to explain the correlation found between the size of the blr and the luminosity. in this picture   the size of the blr in nls1s ( relative to the black hole size ) is larger ( and the emission line width smaller ) than in bls1s simply because their eddington ratio is larger.
we study the heavy - heavy - light quark ( @xmath0 ) potential in su(3 ) quenched lattice qcd, and discuss one of the roles of the finite - mass valence quark in the inter - quark potential.   monte carlo simulations are performed with the standard gauge action on the @xmath1 lattice at @xmath2 and the @xmath3-improved wilson fermion action at four hopping parameters. for statistical improvement  , the gauge configuration is fixed with the coulomb gauge.   we calculate the potential energy of @xmath0 systems as a function of the inter - heavy - quark distance @xmath4 in the range of @xmath5 0.8 fm. the @xmath0 potential is well described with a coulomb plus linear potential, and the effective string tension between the two heavy quarks is significantly smaller than the string tension @xmath6 gev / fm.   it would generally hold that the effect of the finite - mass valence quark reduces the inter - two - quark confinement force in baryons.
a short review is presented of a recently developed computational approach which allows the study of the resistance noise over the full range of bias values, from the linear regime up to electrical breakdown.   resistance noise is described in terms of two competing processes in a random resistor network.   the two processes are thermally activated and driven by an electrical bias. in the linear regime, a scaling relation has been found between the relative variance of resistance fluctuations and the average resistance.   the value of the critical exponent is significantly higher than that associated with 1/f noise. in the nonlinear regime, occurring when the bias overcomes the threshold value, the relative variance of resistance fluctuations scales with the bias.   two regions can be identified in this regime : a moderate bias region and a pre - breakdown one. in the first region, the scaling exponent has been found independent of the values of the model parameters and of the bias conditions.   a strong nonlinearity emerges in the pre - breakdown region which is also characterized by non - gaussian noise.   the results compare well with measurements of electrical breakdown in composites and with electromigration experiments in metallic lines.    2
we try to address quantitatively the question whether a new mass is needed to fit current supernovae data. for this purpose  , we consider an infra - red modification of gravity that does not contain any new mass scale but systematic subleading corrections proportional to the curvature.   the modifications are of the same type as the one recently derived by enforcing the  ultra strong equivalence principle " ( usep ) upon a friedmann - lematre - robertson - walker universe in the presence of a scalar field.   the distance between two comoving observers is altered by these corrections and the observations at high redshift affected at any time during the cosmic evolution. while the specific values of the parameters predicted by usep are ruled out, there are regions of parameter space that fit snia data very well.   this allows an interesting possibility to explain the apparent cosmic acceleration today without introducing either a dark energy component or a new mass scale.
the giant vortex states of a multiply connected superconductor, with radius comparable to the penetration depth and the coherence length, are theoretically investigated based on the nonlinear ginzburg - landau theory, in which the induced magnetic field by the super - currents is accurately taken into account.   the solutions of ginzburg - landau equations are found to be actually independent of the angular momentum l in a gauge invariant point of view, provided that the hole is in the center.   different cases with the paramagnetic current, the diamagnetic current, and the coexistence of the above two, have been studied numerically.   the interpretation of the l - independent solutions of ginzburg - landau equations is given based on the same principle of aharonov - bohm effect, and could be observed by little - parks like oscillations near the phase boundary.
we study the structure of logical operators in local @xmath0-dimensional quantum codes, considering both subsystem codes with geometrically local gauge generators and codes defined by geometrically local commuting projectors.   we show that if the code distance is @xmath1, then any logical operator can be supported on a set of specified geometry containing @xmath2 qubits, where @xmath3 and @xmath4 is the code length.   our results place limitations on partially self - correcting quantum memories, in which at least some logical operators are protected by energy barriers that grow with system size.   we also show that for any two - dimensional local commuting projector code there is a nontrivial logical `` string '' operator supported on a narrow strip, where the operator is only slightly entangling across any cut through the strip.
in the analysis of broad absorption line ( bal ) quasar spectra, keck hires spectra are a useful complement to lower resolution hst and ground based spectra.   the hires spectra provide accurate parameters for narrow, intervening type absorption systems including lyman limit systems and a direct measurement of the smoothness of bal features.   the smoothness of the troughs is related to the number of `` clouds '' in the bal region if the bal region consists of clouds.   the hires spectra, especially for @xmath0 @xmath1 2 bal quasars, are also a source of high quality absorption templates.   all of the bal features are apparently resolved in the high resolution spectra ( r @xmath1 45 000 ), while low resolution ( r @xmath1 1000 ) spectra do not always resolve features belonging to the outflow.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
recent spectroscopic observations have revealed the ubiquitous presence of blueward asymmetries of emission lines formed in the solar corona and transition region.   these asymmetries are most prominent in loop footpoint regions, where a clear correlation of the asymmetry with the doppler shift and line width determined from the single gaussian fit is found.   such asymmetries suggest at least two emission components : a primary component accounting for the background emission and a secondary component associated with high - speed upflows. the latter has been proposed to play a vital role in the coronal heating process and   there is no agreement on its properties. here   we slightly modify the initially developed technique of red - blue ( rb ) asymmetry analysis and apply it to both artificial spectra and spectra observed by the euv imaging spectrometer onboard hinode, and demonstrate that the secondary component usually contributes a few percent of the total emission, has a velocity ranging from 50 to 150  km  s@xmath0 and a gaussian width comparable to that of the primary one in loop footpoint regions.   the results of the rb asymmetry analysis are then used to guide a double gaussian fit and we find that the obtained properties of the secondary component are generally consistent with those obtained from the rb asymmetry analysis. through a comparison of the location, relative intensity, and velocity distribution of the blueward secondary component with the properties of the upward propagating disturbances revealed in simultaneous images from the atmospheric imaging assembly onboard the solar dynamics observatory, we find a clear association of the secondary component with the propagating disturbances.
we propose a new approach to comparing simulated observations that enables us to determine the significance of the underlying physical effects.   we utilize the methodology of experimental design, a subfield of statistical analysis, to establish a framework for comparing simulated position - position - velocity data cubes to each other.   we propose three similarity metrics based on methods described in the literature : principal component analysis, the spectral correlation function, and the cramer multi - variate two sample similarity statistic.   using these metrics, we intercompare a suite of mock observational data of molecular clouds generated from magnetohydrodynamic simulations with varying physical conditions. using this framework  , we show that all three metrics are sensitive to changing mach number and temperature in the simulation sets, but can not detect changes in magnetic field strength and initial velocity spectrum.   we highlight the shortcomings of one - factor - at - a - time designs commonly used in astrophysics and propose fractional factorial designs as a means to rigorously examine the effects of changing physical properties while minimizing the investment of computational resources.
topology optimization offers great opportunities to design permanent magnetic systems that have specific external field characteristics.   additive manufacturing of polymer bonded magnets with an end - user 3d printer can be used to manufacture permanent magnets with structures that have been difficult or impossible to manufacture previously.   this work combines these two powerful methods to design and manufacture permanent magnetic system with specific properties.   the topology optimization framework is simple, fast, and accurate.   it can be also used for reverse engineering of permanent magnets in order to find the topology from field measurements.   furthermore, a magnetic system that generate a linear external field above the magnet is presented. with a volume constraint   the amount of magnetic material can be minimized without losing performance.   simulations and measurements of the printed system show a very good agreement.
we use langer s approach to calculate the reaction rate of a system of two ( classical ) spins interacting via the exchange coupling @xmath0 in a magnetic field @xmath1, with uniaxial anisotropy of constant @xmath2.   we find a particular value of the exchange coupling, that is @xmath3, where @xmath4, which separates two regimes corresponding to a two - stage and one - stage switching.   for @xmath5 the nel - brown result for the one - spin problem is recovered.
ls  i+61 303 has been detected by the cherenkov telescope magic at very high energies, presenting a variable flux along the orbital motion with a maximum clearly separated from the periastron passage. in the light of the new observational constraints  , we revisit the discussion of the production of high - energy gamma rays from particle interactions in the inner jet of this system.   the hadronic contribution could represent a major fraction of the tev emission detected from this source.   the spectral energy distribution resulting from @xmath0 interactions is recalculated.   opacity effects introduced by the photon fields of the primary star and the stellar decretion disk are shown to be essential in shaping the high - energy gamma - ray light curve at energies close to 200 gev.   we also present results of monte carlo simulations of the electromagnetic cascades developed very close to the periastron passage.   we conclude that a hadronic microquasar model for the gamma - ray emission in ls  i + 61 303 can reproduce the main features of its observed high - energy @xmath1-ray flux.   example.eps gsave newpath 20 20 moveto 20 220 lineto 220 220 lineto 220 20 lineto closepath 2 setlinewidth gsave.4 setgray fill grestore stroke grestore
we present spike ( spectrometry processing innovative kernel ), an open - source python package dedicated to fourier spectroscopies.   it provides basic functionalities such as apodisation, a complete set of fourier transforms, phasing ( for nmr ), peak - picking, baseline correction and also tools such as linear prediction. beside its versatility,   the most prominent novelty of this package is to incorporate new tools for big data processing.   this is exemplified by its ability to handle the processing and visualization of very large data - sets, with multiprocessor capabilities and a low memory footprint.   the software contains also all the tools necessary for the specific fast processing and visualization of 2d - fticr - ms data - sets.
we generalize tensor - scalar theories of gravitation by the introduction of an abnormally weighting type of energy.   this theory of tensor - scalar anomalous gravity is based on a relaxation of the weak equivalence principle that is now restricted to ordinary visible matter only. as a consequence,   the convergence mechanism toward general relativity is modified and produces naturally cosmic acceleration as an inescapable gravitational feedback induced by the mass - variation of some invisible sector.   the cosmological implications of this new theoretical framework are studied.   this glimpses at an enticing new symmetry between the visible and invisible sectors, namely that the scalar charges of visible and invisible matter are exactly opposite.   address = cnrs, laboratoire univers et thories ( luth ), umr 8102 cnrs, observatoire de paris, universit paris diderot ; 5 place jules janssen, 92190 meudon, france     address = department of mathematics, university of namur ( fundp ) ; rue de bruxelles, 61, b-5000 namur, belgium, altaddress = center for particle physics and phenomenology ( cp3 ), universit catholique de louvain, chemin du cyclotron, 2, b-1348 louvain - la - neuve, belgium
in this paper, we develop a structure - preserving discretization of the lagrangian framework for electromagnetism, combining techniques from _ variational integrators _ and _ discrete differential forms_. this leads to a general family of variational, multisymplectic numerical methods for solving maxwell s equations that automatically preserve key symmetries and invariants.    in doing so  , we demonstrate several new results, which apply both to some well - established numerical methods and to new methods introduced here.   first, we show that yee s finite - difference time - domain ( fdtd ) scheme, along with a number of related methods, are multisymplectic and derive from a discrete lagrangian variational principle.   second, we generalize the yee scheme to unstructured meshes, not just in space but in @xmath0-dimensional spacetime.   this relaxes the need to take uniform time steps, or even to have a preferred time coordinate at all. finally, as an example of the type of methods that can be developed within this general framework, we introduce a new _ asynchronous variational integrator _ ( avi ) for solving maxwell s equations.   these results are illustrated with some prototype simulations that show excellent energy and conservation behavior and lack of spurious modes, even for an irregular mesh with asynchronous time stepping.
we present a variational treatment of the ground state of the 2-leg @xmath0-@xmath1 ladder, which combines the dimer and the hard - core boson models into one effective model.   this model allows us to study the local structure of the hole pairs as a function of doping.   a second order recursion relation is used to generate the variational wave function, which substantially simplifies the computations.   we obtain good agreement with numerical density matrix renormalization group results for the ground state energy in the strong coupling regime.   we find that the local structure of the pairs depends upon whether the ladder is slightly or strongly dopped.
we present a multi - wavelength analysis of the host galaxy of short - duration gamma - ray burst ( grb ) 150101b.   follow - up optical and x - ray observations suggested that the host galaxy, 2masx  j12320498 - 1056010, likely harbors a low - luminosity active galactic nuclei ( agn ).   our modeling of the spectral energy distribution ( sed ) has confirmed the nature of the agn, making it the first reported grb host that contains an agn.   we have also found the host galaxy is a massive elliptical galaxy with stellar population of @xmath0, one of the oldest among the short - duration grb hosts.   our analysis suggests that the host galaxy can be classified as an x - ray bright, optically normal galaxy ( xbong ), and the central agn is likely dominated by a radiatively inefficient accretion flow ( riaf ).   our work explores interesting connection that may exist between grb and agn activities of the host galaxy, which can help understand the host environment of the grb events and the roles of agn feedback.
linear gyro - kinetic simulations of the classical tearing mode in three - dimensional toroidal geometry were performed using the global gyro kinetic turbulence code, gkw.   the results were benchmarked against a cylindrical ideal mhd and analytical theory calculations. the stability, growth rate and frequency of the mode were investigated by varying the current profile, collisionality and the pressure gradients. both collision - less and semi - collisional tearing modes were found with a smooth transition between the two. a residual, finite, rotation frequency of the mode even in the absense of a pressure gradient   is observed which is attributed to toroidal finite larmor - radius effects.   when a pressure gradient is present at low collisionality, the mode rotates at the expected electron diamagnetic frequency.   however the island rotation reverses direction at high collisionality.   the growth rate is found to follow a @xmath0 scaling with collisional resistivity in the semi - collisional regime, closely following the semi - collisional scaling found by fitzpatrick.   the stability of the mode closely follows the stability using resistive mhd theory, however a modification due to toroidal coupling and pressure effects is seen.
the relationships between the effective surface ( @xmath0 ) and internal temperatures of neutron stars ( nss ) with and without accreted envelopes are calculated for @xmath1  k using new data on the equation of state and opacities in the outer ns layers.   we examine various models of accreted layers ( h, he, c, o shells produced by nuclear transformations in accreted matter ).   we employ new opacity library ( opal ) radiative opacities for h, he, and fe. in the outermost   ns layers, we implement the modern opal equation of state for fe, and the saumon  chabrier equation of state for h and he. the updated thermal conductivities of degenerate electrons include the debye  waller factor for the electron - phonon scattering in solidified matter, while in liquid matter they include the contributions from electron - ion collisions ( evaluated with non - born corrections and with the ion structure factors in responsive electron background ) and from the electron - electron collisions. for @xmath2 k,   the electron conduction in non - degenerate layers of the envelope becomes important, reducing noticeably the temperature gradient.   the accreted matter further decreases this gradient at @xmath3 k. even a small amount of accreted matter ( with mass @xmath4 ) affects appreciably the ns cooling, leading to higher @xmath0 at the neutrino cooling stage and to lower @xmath0 at the subsequent photon stage.
we present the first results on the black hole candidate xte j1752223 from the gas slit camera ( gsc ) on - board the monitor of all - sky x - ray image ( maxi ) on the international space station. including the onset of the outburst reported by the proportional counter array on - board the rossi x - ray timing explorer on 2009 october 23,   the maxi / gsc has been monitoring this source approximately 10 times per day with a high sensitivity in the 220 kev band.   xte j1752223 was initially in the low / hard state during the first 3 months.   an anti - correlated behavior between the 24 kev and 420 kev bands were observed around january 20, 2010, indicating that the source exhibited the spectral transition to the high / soft state.   a transient radio jet may have been ejected when the source was in the intermediate state where the spectrum was roughly explained by a power - law with a photon index of 2.53.0.   the unusually long period in the initial low / hard state implies a slow variation in the mass accretion rate, and the dramatic soft x - ray increase may be explained by a sudden appearance of the accretion disk component with a relatively low innermost temperature ( 0.40.7 kev ).   such a low temperature might suggest that the maximum accretion rate was just above the critical gas evaporation rate required for the state transition.
we present a new method for estimating the corotation radius in tightly wound spiral galaxies, through analysis of the radial variation of the offset between arms traced by the potential ( p - arms ) and those traced by dust ( d - arms ).   we have verified the predictions of semi - analytical theory through hydrodynamical simulations and have examined the uniqueness of the galactic parameters that can be deduced by this method.   we find that if the range of angular offsets measured at different radii in a galaxy is greater than around @xmath0, it is possible to locate the radius of corotation to within @xmath1%.   we argue that the relative location of the p- and d - arms provides more robust constraints on the galactic parameters than can be inferred from regions of enhanced star formation ( sf - arms ), since interpretation of the latter involves uncertainties due to reddening and the assumed star formation law.   we thus stress the importance of k - band studies of spiral galaxies.   hydrodynamics  methods : numerical  galaxies : ism  galaxies : spiral  galaxies : structure
this article gives an overview of many of the recent developments in understanding the structure of relativistic scattering amplitudes in gauge theories ranging from qcd to @xmath0 super - yang - mills theory, as well as ( super)gravity.   i also provide a pedagogical introduction to some of the basic tools used to organize and illuminate the color and kinematic structure of amplitudes.   this article is an invited review introducing a special issue of journal of physics a devoted to `` scattering amplitudes in gauge theories ''.
the thermodynamic entropy of an isolated system is given by its von neumann entropy. over the last few years  , there is an intense activity to understand thermodynamic entropy from the principles of quantum mechanics.   more specifically, is there a relation between the ( von neumann ) entropy of entanglement between a system and some ( separate ) environment is related to the thermodynamic entropy?   it is difficult to obtain the relation for many body systems, hence, most of the work in the literature has focused on small number systems. in this work,   we consider black - holes  that are simple yet macroscopic systems  and show that a direct connection could not be made between the entropy of entanglement and the hawking temperature. in this work, within the adiabatic approximation,   we explicitly show that the hawking temperature is indeed given by the rate of change of the entropy of entanglement across a black hole s horizon with regard to the system energy.   this is yet another numerical evidence to understand the key features of black hole thermodynamics from the viewpoint of quantum information theory.
we derive the exact solution for the optical conductivity @xmath0 of one hole in the holstein-@xmath1-@xmath2 model in the framework of dynamical mean - field theory ( dmft ).   we investigate the magnetic and phonon features associated with polaron formation as a function of the exchange coupling @xmath2, of the electron - phonon interaction @xmath3 and of the temperature.   our solution directly relates the features of the optical conductivity to the excitations in the single - particle spectral function, revealing two distinct mechanisms of closing and filling of the optical pseudogap that take place upon varying the microscopic parameters.   we show that the optical absorption at the polaron crossover is characterized by a coexistence of a magnon peak at low frequency and a broad polaronic band at higher frequency.   an analytical expression for @xmath0 valid in the polaronic regime is presented.
using the results of recent optical surveys we conclude that the _ non_-detection of quasars down to faint magnitudes implies a significant flattening of the high redshift ( @xmath0 ) optical active galactic nuclei ( agn ) luminosity function for @xmath1.   we find that all the data are consistent with a faint - end slope for the optical agn luminosity function of @xmath2 and @xmath3, at the 90% and 99% confidence level respectively, flatter than the bright - end slope of @xmath4.   we also show that x - ray deep surveys have probed even fainter magnitudes than the optical ones yielding more significant constraints on the shallow faint - end slope of the optical luminosity function.   the inclusion of type ii agn candidates, detected in the _ chandra _ deep fields, hints towards an higher normalization for the total agn luminosity function, if these sources lie at @xmath5.   we then discuss simple theoretical models of agn formation and evolution in the context of cold dark matter cosmology.   the comparison with the total agn luminosity function favors a redshift - dependent relation between black hole and dark matter halo masses of the type @xmath6, with @xmath7, compatible with independent studies from statistical analysis and rotation curve measurements.   finally we compute the quasar contribution to reionization to be @xmath8 at @xmath0, up to @xmath9 when integrated within @xmath10, significantly smaller than that from galaxies.
the flux and nuclear composition of ultra - high energy cosmic rays depend on the cosmic distribution of their sources.   data from cosmic ray observatories are yet inconclusive about their exact location or distribution, but provide a measure for the average local density of these emitters. due to the discreteness of the emitters the flux and nuclear composition is expected to show ensemble fluctuations on top of the statistical variations, _   i.e. _  `` cosmic variance ''.   this effect is strongest for the most energetic cosmic rays due to the limited propagation distance in the cosmic radiation background and is hence a local phenomenon. for the statistical analysis of cosmic ray emission models   it is important to quantify the possible level of this variance. in this paper   we present a completely analytic method that describes the variation of the flux and nuclear composition with respect to the local source density.   we highlight that proposed future space - based observatories with exposures of @xmath0 will attain sensitivity to observe these spectral fluctuations in the cosmic ray energy spectrum at earth relative to the overall power - law fit.
we investigate the relative sensitivities of several tests for deviations from gaussianity in the primordial distribution of density perturbations.   we consider models for non - gaussianity that mimic that which comes from inflation as well as that which comes from topological defects.   the tests we consider involve the cosmic microwave background ( cmb ), large - scale structure ( lss ), high - redshift galaxies, and the abundances and properties of clusters.   we find that the cmb is superior at finding non - gaussianity in the primordial gravitational potential ( as inflation would produce ), while observations of high - redshift galaxies are much better suited to find non - gaussianity that resembles that expected from topological defects.   we derive a simple expression that relates the abundance of high - redshift objects in non - gaussian models to the primordial skewness.   # 1#1 # 1 # 1#23.6pt   +   +    cosmology : theory - galaxies - clusters of galaxies - large scale structures - cosmic microwave background - methods : analytical
we investigate the properties of astrophysical electromagnetic cascades in matter, photon gas and magnetic fields, and discuss similarities and differences between characteristics of electron - photon showers developed in these 3 substances.   we apply the same computational technique based on solution of the adjoint cascade equations to all 3 types of cascades, and present precise numerical calculations of cascade curves and broad - band energy spectra of secondary electrons and photons at different penetration lengths.   electromagnetic cascades, high energy processes, gamma - ray sources
in transport calculations for molecular junctions based on density functional theory the choice of exchange and correlation functional may dramatically affect the results. in particular local and semi - local functionals tend to over - delocalize the molecular levels thus artificially increasing their broadening.   in addition the same molecular levels are usually misplaced with respect to the fermi level of the electrodes.   these shortfalls are reminiscent of the inability of local functionals to describe mott - hubbard insulators, but they can be corrected with a simple and computationally undemanding self - interaction correction scheme.   we apply such a scheme, as implemented in our transport code _   smeagol _, to a variety of phenyl - based molecular junctions attached to gold electrodes.   in general the corrections reduce the current, since the resonant kohn - sham states of the molecule are shifted away from the contact fermi level.   in contrast, when the junction is already described as insulating by local exchange and correlation potentials, the corrections are minimal and the @xmath0-@xmath1 is only weakly modified.
we discuss utility based pricing and hedging of jump diffusion processes with emphasis on the practical applicability of the framework.   we point out two difficulties that seem to limit this applicability, namely drift dependence and essential risk aversion independence.   we suggest to solve these by a re - interpretation of the framework.   this leads to the notion of an implied drift.   we also present a heuristic derivation of the marginal indifference price and the marginal optimal hedge that might be useful in numerical computations.
exemplar - based models have achieved great success on localizing the parts of semi - rigid objects.   however, their efficacy on highly articulated objects such as humans is yet to be explored.   inspired by hierarchical object representation and recent application of deep convolutional neural networks ( dcnns ) on human pose estimation, we propose a novel formulation that incorporates both hierarchical exemplar - based models and dcnns in the spatial terms.   specifically, we obtain more expressive spatial models by assuming independence between exemplars at different levels in the hierarchy ; we also obtain stronger spatial constraints by inferring the spatial relations between parts at the same level. as our method strikes a good balance between expressiveness and strength of spatial models,   it is both effective and generalizable, achieving state - of - the - art results on different benchmarks : leeds sports dataset and cub-200 - 2011.   = 1
the phases of the fourier modes appearing in a plane - wave expansion of cosmological density fields play a vital role in determining the morphology of gravitationally - developed clustering.   we demonstrate this qualitatively and quantitatively using simulations.   in particular, we use cross - correlation and rank - correlation techniques to quantify the agreement between a simulated distribution and phase - only reconstructions.   the phase - only reconstructions exhibit a high degree of correlation with the original distributions, showing how meaningful spatial reconstruction of cosmological density fields depends more on phase accuracy than on amplitudes.   cosmology : theory  large - scale structure of the universe  methods : statistical
we formulate a kinetic theory of self - interacting meson fields with an aim to describe the freezeout stage of the space - time evolution of matter in ultrarelativistic nuclear collisions.   kinetic equations are obtained from the heisenberg equation of motion for a single component real scalar quantum field taking the mean field approximation for the non - linear interaction.   the mesonic mean field obeys the classical non - linear klein - gordon equation with a modification due to the coupling to mesonic quasi - particle excitations which are expressed in terms of the wigner functions of the quantum fluctuations of the meson field, namely the statistical average of the bilinear forms of the meson creation and annihilation operators. in the long wavelength limit,   the equations of motion of the diagonal components of the wigner functions take a form of vlasov equation with a particle source and sink which arises due to the non - vanishing off - diagonal components of the wigner function expressing coherent pair - creation and pair - annihilation process in the presence of non - uniform condensate.   we show that in the static homogeneous system, these kinetic equations reduce to the well - known gap equation in the hartree approximation, and hence they may be considered as a generalization of the hartree approximation method to non - equilibrium systems. as an application of these kinetic equations, we compute the dispersion relations of the collective mesonic excitations in the system near equilibrium.   meson condensate ; vlasov equation
a lower bound on the amount of noise that must be added to a ghz - like entangled state to make it separable ( also called the random robustness ) is found using the transposition condition.   the bound is applicable to arbitrary numbers of subsystems, and dimensions of hilbert space, and is shown to be exact for qubits.   the new bound is compared to previous such bounds on this quantity, and found to be stronger in all cases.   it implies that increasing the number of subsystems, rather than increasing their hilbert space dimension is a more effective way of increasing entanglement. an explicit decomposition into an ensemble of separable states, when the state is not entangled, is given for the case of qubits.    2
we study the diphoton excesses near @xmath0  gev recently reported by the atlas and cms collaborations within the context of a phenomenologically interesting intersecting / magnetized d - brane model on a toroidal orientifold.   it is shown that the model contains a sm singlet scalar as well as vector - like quarks and leptons.   in addition, it is shown that the singlet scalar has yukawa couplings with vector - like quarks and leptons such that it may be produced in proton - proton collisions via gluon fusion as well as decay to diphotons through loops involving the vector - like quarks. moreover,   the required vector - like quarks and leptons may appear in complete @xmath1 multiplets so that gauge coupling unification may be maintained.   finally, it is shown that the diphoton signal may be accommodated within the model.
we consider the effect of intermolecular interactions on the optimal size - distribution of @xmath0 hard spheres that occupy a fixed total volume. when we minimize the free - energy of this system, within the percus - yevick approximation  , we find that no solution exists beyond a quite low threshold ( @xmath1 ).   monte carlo simulations reveal that beyond this density, the size - distribution becomes bi - modal.   such distributions can not be reproduced within the percus - yevick approximation.   we present a theoretical argument that supports the occurrence of a non - monotonic size - distribution and emphasizing the importance of finite size effects.
we find that single - star mechanisms for intermediate luminosity optical transients ( ilots ; red transients ; red novae ) which are powered by energy release in the core of asymptotic giant branch ( agb ) stars are likely to eject the entire envelope, and hence can not explain ilots in agb and similar stars.   there are single - star and binary models for the powering of ilots, which are eruptive stars with peak luminosities between those of novae and supernovae. in single - star models   the ejection of gas at velocities of @xmath0 and a possible bright ionizing flash, require a shock to propagate from the core outward. using a self similar solution to follow the propagation of the shock through the envelope of two evolved stellar models, a @xmath1 agb star and an @xmath2 yellow supergiant ( ysg ) star, we find that the shock that is required to explain the observed mass loss also ejects most of the envelope.   we also show that for the event to have a strong ionizing flash the required energy expels most of the envelope.   the removal of most of the envelope is in contradiction with observations.   we conclude that single - star models for ilots of evolved giant stars encounter severe difficulties.
how the accreted mass settling on the surface of a neutron star affects the topology of the magnetic field and how the secular evolution of the binary system depends on the magnetic field change is still an open issue.   we report evidence for a clear drop in the observed magnetic field in the accreting pulsar v0332 + 53 after undergoing a bright 3-month long x - ray outburst.   we determine the field from the position of the fundamental cyclotron line in its x - ray spectrum and relate it to the luminosity.   for equal levels of luminosity, in the declining phase we measure a systematically lower value of the cyclotron line energy with respect to the rising phase.   this results in a drop of @xmath0 g of the observed field between the onset and the end of the outburst.   the settling of the accreted plasma onto the polar cap seems to induce a distortion of the magnetic field lines weakening their intensity along the accretion columns.   therefore the dissipation rate of the magnetic field could be much faster than previously estimated, unless the field is able to restore its original configuration on a time - scale comparable with the outbursts recurrence time.        x - rays : binaries  pulsars : individual : v0332 + 53  magnetic fields   facility : _ swift _
we present a sensor capable of detecting solution - based nanoparticles using an optical fiber tip functionalized with a photonic crystal cavity. when sensor tips are retracted from a nanoparticle solution after being submerged, we find that a combination of convective fluid forces and optically - induced trapping cause an aggregation of nanoparticles to form directly on cavity surfaces.   a simple readout of quantum dot photoluminescence coupled to the optical fiber shows that nanoparticle presence and concentration can be detected through modified cavity properties.   our sensor can detect both gold and iron oxide nanoparticles and can be utilized for molecular sensing applications in biomedicine.
we have tested the application to sloan digital sky survey data of the software package match, which fits color - magnitude diagrams ( cmds ) to estimate stellar population parameters and distances. these tests on a set of six globular clusters show that these techniques recover their known properties.   new ways of using the cmd - fitting software enable us to deal with an extended distribution of stars along the line - of - sight, to constrain the overall properties of sparsely populated objects, and to detect the presence of stellar overdensities in wide - area surveys.   we then also apply match to cmds for twelve recently discovered milky way satellites to derive in a uniform fashion their distances, ages and metallicities. while the majority of them appear consistent with a single stellar population, cvn i, uma ii, and leo t exhibit ( from sdss data alone ) a more complex history with multiple epochs of star formation.
tumor growth has long been a target of investigation within the context of mathematical and computer modelling.   the objective of this study is to propose and analyze a two - dimensional probabilistic cellular automata model to describe avascular solid tumor growth, taking into account both the competition between cancer cells and normal cells for nutrients and/or space and a time - dependent proliferation of cancer cells.   gompertzian growth, characteristic of some tumors, is described and some of the features of the time - spatial pattern of solid tumors, such as compact morphology with irregular borders, are captured.   the parameter space is studied in order to analyze the occurrence of necrosis and the response to therapy.   our findings suggest that transitions exist between necrotic and non - necrotic phases ( no - therapy cases ), and between the states of cure and non - cure ( therapy cases ). to analyze cure,   the control and order parameters are, respectively, the highest probability of cancer cell proliferation and the probability of the therapeutic effect on cancer cells. with respect to patterns, it is possible to observe the inner necrotic core and the effect of the therapy destroying the tumor from its outer borders inwards.       tumor growth, cellular automata, parameter space, necrosis, therapy
differential elliptic flow out to @xmath0 gev / c and particle spectra are calculated using the mpc elastic parton cascade model for au+au at @xmath1 @xmath2 gev.   the evolution is computed from parton transport theory, followed by hadronization either via independent fragmentation or by imposing parton - hadron duality. with pqcd elastic cross sections,   very large initial gluon densities @xmath3 are required to reproduce the data measured by the star collaboration.   in addition, elliptic flow and the @xmath4 spectra are shown to be very sensitive to particle subdivision.
the multiple futile cycle is an important building block in networks of chemical reactions arising in molecular biology. a typical process which it describes is the addition of @xmath0 phosphate groups to a protein.   it can be modelled by a system of ordinary differential equations depending on parameters.   the special case @xmath1 is called the dual futile cycle.   the main result of this paper is a proof that there are parameter values for which the system of ode describing the dual futile cycle has two distinct stable stationary solutions. the proof is based on bifurcation theory and geometric singular perturbation theory.   an important entity built of three coupled multiple futile cycles is the mapk cascade.   it is explained how the ideas used to prove bistability for the dual futile cycle might help to prove the existence of periodic solutions for the mapk cascade.
we present a proposal for optically implementing the quantum game of the two - player quantum prisoner s dilemma involving nonmaximally entangled states by using beam splitters, phase shifters, cross - kerr medium, photon detector and the single - photon representation of quantum bits.   pacs number(s ) : 03.67.-a, 03.67.lx, 42.50.dv
we study the nature of motion in a 3d potential composed of perturbed elliptic oscillators.   our technique is to use the results obtained from the 2d potential in order to find the initial conditions generating regular or chaotic orbits in the 3d potential.   both 2d and 3d potentials display exact periodic orbits together with extended chaotic regions.   numerical experiments suggest, that the degree of chaos increases rapidly, as the energy of the test particle increases. about @xmath0 of the phase plane of the 2d system   is covered by chaotic orbits for large energies.   the regular or chaotic character of the 2d orbits is checked using the @xmath1 dynamical spectrum, while for the 3d potential we use the @xmath1 spectrum, along with the @xmath2 spectral method.   comparison with other dynamical indicators shows that the @xmath1 spectrum gives fast and reliable information about the character of motion.   = 1
this article studies the estimation of the causal effect of a time - varying treatment on time - to - an - event or on some other continuously distributed outcome.   the paper applies to the situation where treatment is repeatedly adapted to time - dependent patient characteristics.   the treatment effect can not be estimated by simply conditioning on these time - dependent patient characteristics, as they may themselves be indications of the treatment effect.   this time - dependent confounding is common in observational studies.   robins  has proposed the so - called structural nested models to estimate treatment effects in the presence of time - dependent confounding. in this article   we provide a conceptual framework and formalization for structural nested models in continuous time.   we show that the resulting estimators are consistent and asymptotically normal.   moreover, as conjectured in robins , a test for whether treatment affects the outcome of interest can be performed without specifying a model for treatment effect.   we illustrate the ideas in this article with an example.   .
in this paper, we study shock structures of collisionless shocks in partially ionized plasmas by means of two - dimensional hybrid simulations, where the shock is a perpendicular shock with shock velocity @xmath0 and the upstream ionization fraction is 0.5.   we find that large density fluctuations and large magnetic fields fluctuations are generated both in the upstream and downstream regions.   in addition, we find that the velocity distribution of downstream hydrogen atoms has three components. observed shock structures suggest that diffusive shock acceleration can operate at perpendicular shocks propagating into partially ionized plasmas in real three - dimensional systems.
with teragauss magnetic fields, surface gravity sufficiently strong to significantly modify light paths, central densities higher than that of a standard nucleus, and rotation periods of only hundredths of a second, young neutron stars are sites of some of the most extreme physical conditions known in the universe.   they generate magnetic winds with particles that are accelerated to energies in excess of a tev.   these winds form synchrotron - emitting bubbles as the particle stream is eventually decelerated to match the general expansion caused by the explosion that formed the neutron stars.   the structure of these pulsar wind nebulae allow us to infer properties of the winds and the pulsating neutron stars themselves.   the surfaces of the the stars radiate energy from the rapidly cooling interiors where the physical structure is basically unknown because of our imprecise knowledge of the strong interaction at ultrahigh densities. here   i present a summary of recent measurements that allow us to infer the birth properties of neutron stars and to probe the nature of their winds, the physics of their atmospheres, and the structure of their interiors.   neutron star, pulsar wind, cooling, jets, filaments
we propose using short - period superlattices as substrates to control the vibrational relaxation dynamics of adsorbate overlayers.   the mass modulation of superlattices creates both band gaps and large spectral enhancements in the phonon density of states.   these modifications can dramatically alter the coupling between vibrational modes of the adsorbate overlayer and the substrate lattice, thereby significantly affecting the lifetime of adsorbate modes.
we develop a composite dirac fermion theory for the fractional quantum hall effects ( qhe ) near charge neutrality in graphene.   we show that the interactions between the composite dirac fermions lead to a dynamical mass generation through exciton condensation.   the four - fold spin - valley degeneracy is fully lifted due to the mass generation and the exchange effects such that the odd - denominator fractional qhe observed in the vicinity of charge neutrality can be understood in terms of the integer qhe of the composite dirac fermions. at the filling factor @xmath0  , we show that the massive composite dirac fermion liquid is unstable against chiral @xmath1-wave pairing for weak coulomb interactions and the ground state is a paired nonabelian quantum hall state described by the moore - read pfaffian in the long wavelength limit.
we calculate the fermion propagator in flrw spacetimes with constant deceleration @xmath0, @xmath1 for excited states. for fermions   whose mass is generated by a scalar field through a yukawa coupling @xmath2, we assume @xmath3.   we first solve for the mode functions by splitting the spinor into a direct product of helicity and chirality spinors.   we also allow for non - vacuum states.   we normalise the spinors using a consistent canonical quantisation and by requiring orthogonality of particle and anti - particle spinors.   we apply our propagator to calculate the one loop effective action and renormalise using dimensional regularisation.   since the hubble parameter is now treated dynamically, this paves the way to study the dynamical backreaction of fermions on the background spacetime.
the resummed differential thrust rate in @xmath0 annihilation is calculated using soft - collinear effective theory ( scet ).   the resulting distribution in the two - jet region ( @xmath1 is found to agree with the corresponding expression derived by the standard approach. a matching procedure to account for finite corrections at @xmath2   is then described.   there are two important advantages of the scet approach.   first, scet manifests a dynamical seesaw scale @xmath3 in addition to the center - of - mass energy @xmath4 and the jet mass scale @xmath5.   thus, the resummation of logs of @xmath6 can be cleanly distinguished from the resummation of logs of @xmath7.   second, finite parts of loop amplitudes appear in specific places in the perturbative distribution : in the matching to the hard function, at the scale @xmath4, in matching to the jet function, at the scale @xmath8, and in matching to the soft function, at the scale @xmath9.   this allows for a consistent merger of fixed order corrections and resummation.   in particular, the total nlo @xmath0 cross section is reproduced from these finite parts without having to perform additional infrared regulation.   * resummation and nlo matching of event shapes + with effective field theory *    matthew d. schwartz +
using mean - field theory, we study the equilibrium properties of boson - fermion mixtures confined in a harmonic pancake - shaped trap at zero temperature. when the modulus of the @xmath0-wave scattering lengths are comparable to the mixture thickness, two - dimensional scattering events introduce a logarithmic dependence on density in the coupling constants, greatly modifying the density profiles themselves.   we show that for the case of a negative boson - fermion three - dimensional @xmath0-wave scattering length, the dimensional crossover stabilizes the mixture against collapse and drives it towards spatial demixing.
item recommendation task predicts a personalized ranking over a set of items for individual user.   one paradigm is the rating - based methods that concentrate on explicit feedbacks and hence face the difficulties in collecting them.   meanwhile, the ranking - based methods are presented with rated items and then rank the rated above the unrated.   this paradigm uses widely available implicit feedback but it usually ignores some important information : item reviews.   item reviews not only justify the preferences of users, but also help alleviate the cold - start problem that fails the collaborative filtering. in this paper, we propose two novel and simple models to integrate item reviews into matrix factorization based bayesian personalized ranking ( bpr - mf ). in each model, we make use of text features extracted from item reviews via word embeddings. on top of text features we uncover   the review dimensions that explain the variation in users feedback and these review factors represent a prior preference of a user.   experiments on real - world data sets show the benefits of leveraging item reviews on ranking prediction.   we also conduct analyses to understand the proposed models.
using a bayesian approach, we consider the problem of recovering sparse signals under additive sparse and dense noise. typically, sparse noise models outliers, impulse bursts or data loss. to handle sparse noise  , existing methods simultaneously estimate the sparse signal of interest and the sparse noise of no interest. for estimating the sparse signal, without the need of estimating the sparse noise  , we construct a robust relevance vector machine ( rvm ). in the rvm, sparse noise and ever present dense noise   are treated through a combined noise model.   the precision of combined noise is modeled by a diagonal matrix.   we show that the new rvm update equations correspond to a non - symmetric sparsity inducing cost function.   further, the combined modeling is found to be computationally more efficient.   we also extend the method to block - sparse signals and noise with known and unknown block structures. through simulations,   we show the performance and computation efficiency of the new rvm in several applications : recovery of sparse and block sparse signals, housing price prediction and image denoising.
we report the results of experiments aimed at reducing the major problem with cooling flow models of rich cluster x - ray sources : the fact that most of the cooled gas or its products have not been found. here   we show that much of the x - ray emission usually attributed to cooling flows can, in fact, be modeled by a power - law component which is indicative of a source(s ) other than thermal bremsstrahlung from the intracluster medium.   we find that adequate simultaneous fits to rosat pspcb and asca gis / sis spectra of the central regions of ten clusters are obtained for two - component models that includes a thermal plasma component that is attributable to hot intracluster gas and a power - law component that is likely generated by compact sources and/or extended non - thermal emission. for five of the clusters that purportedly have massive cooling flows, the best - fit models have power - law components that contribute @xmath0 30 % of the total flux ( 0.14 - 10.0 kev ) within the central 3 arcminutes. because cooling flow mass deposition rates are inferred from x - ray fluxes, our finding opens the possibility of significantly reducing cooling rates.
in this paper, we present a study on persistent and gradual penumbral decay and correlated decline of the photospheric transverse field component during 10 - 20 hours before a major flare ( x1.8 ) eruption on 2011 september 7.   this long - term pre - eruption behavior is corroborated with the well - imaged pre - flare filament rising, the consistent expansion of coronal arcades overlying the filament, as well as the nlfff modelling results in the literature.   we suggest that both the long - term pre - flare penumbral decay and the transverse field decline are the photospheric manifestation of the gradual rise of the coronal filament - flux rope system.   we also suggest that a c3 flare and subsequent reconnection process preceding the x1.8 flare play an important role in triggering the later major eruption.
we discuss quantum interference phenomena in a system consisting from a laser driven three - level ladder - type emitter possessing orthogonal transition dipoles and embedded in a leaking optical resonator.   the cavity mean - photon number vanishes due to the destructive nature of the interference phenomena.   the effect occurs for some particular parameter regimes which were identified.   furthermore, upper bare - state population inversion occurs as well.
a toy model for magnetic extraction of energy from black hole ( bh ) accretion disk is discussed by considering the restriction of the screw instability to the magnetic field configuration.   three mechanisms of extracting energy magnetically are involved.   (  ) the blandford - znajek ( bz ) process is related to the open magnetic field lines connecting the bh with the astrophysical load ; (  ) the magnetic coupling ( mc ) process is related to the closed magnetic field lines connecting the bh with its surrounding disk ; and (  ) a new scenario ( henceforth the dl process ) for extracting rotational energy from the disk is related to the open field lines connecting the disk with the astrophysical load.   the expressions for the electromagnetic powers and torques are derived by using the equivalent circuits corresponding to the above energy mechanisms.   it turns out that the dl power is comparable with the bz and mc powers as the bh spin approaches unity.   the radiation from a quasi - steady thin disk is discussed in detail by applying the conservation laws of mass, energy and angular momentum to the regions corresponding to the mc and dl processes.   in addition, the poloidal currents and the current densities in bh magnetosphere are calculated by using the equivalent circuits.   black holes, physics of black holes, infall, accretion, and accretion disks, relativity and gravitation 97.60.lf, 04.70.-s, 98.62.mw, 95.30.sf
inspired by lifshitz theory for quantum critical phenomena in condensed matter, horava proposed a theory for quantum gravity with an anisotropic scaling in ultraviolet. in horava - lifshitz gravity ( hlg )  , we have studied the impacts of six types of equations of state on the evolution of various cosmological parameters such as hubble parameters and scale factor. from the comparison of the general relativity gravity with the hlg with detailed and without with non - detailed balance conditions,   remarkable differences are found. also, a noticeable dependence of singular and non - singular big bang on the equations of state is observed.   we conclude that hlg explains various epochs in the early universe and might be able to reproduce the entire cosmic history with and without singular big bang.   * keywords : *  quantum gravity, modified theory of gravity, early universe +   + * pacs nos : *  04.60.-m, 04.50.kd, 98.80.cq
the pierre auger observatory, recently completed, has been operational since 2004. as a hybrid experiment  , it allows for a wide range of measurements of uhecr - induced extensive air showers ( eas ), including measurements of the eas particle content on ground which is sensitive to high - energy hadronic interactions.   we present the results of several independent measurements of the eas muon content on ground in auger data at a primary energy of 10  eev.   we discuss implications on high - energy hadronic interaction models and cosmic ray composition.
we report on the detection with the magic telescopes of very high energy @xmath0-rays from ic  310, a head - tail radio galaxy in the perseus galaxy cluster, observed during the interval november 2008 to february 2010.   the _ fermi _ satellite has also detected this galaxy.   the source is detected by magic at a high statistical significance of @xmath1 in 20.6  hr of stereo data.   the observed spectral energy distribution is flat with a differential spectral index of @xmath2.   the mean flux above @xmath3  gev, between october 2009 and february 2010, @xmath4, corresponds to @xmath5% of crab nebula units. only an upper limit, of @xmath6% of crab nebula units above @xmath3  gev, was obtained with the 2008 data.   this, together with strong hints ( @xmath7 ) of flares in the middle of october and november 2009, implies that the emission is variable.   the magic results favour a scenario with the very high energy emission originating from the inner jet close to the central engine.   more complicated models than a simple one - zone ssc scenario, e.g.  multi - zone ssc, external compton or hadronic, may be required to explain the very flat spectrum and its extension over more than three orders of magnitude in energy.
we establish a framework for oracle identification problems in the continuous variable setting, where the stated problem necessarily is the same as in the discrete variable case, and continuous variables are manifested through a continuous representation in an infinite - dimensional hilbert space.   we apply this formalism to the deutsch - jozsa problem and show that, due to an uncertainty relation between the continuous representation and its fourier - transform dual representation, the corresponding deutsch - jozsa algorithm is probabilistic hence forbids an exponential speed - up, contrary to a previous claim in the literature.   december 18, 2008
in this paper we discuss the chemical evolution of elliptical galaxies and its consequences on the evolution of the intracluster medium ( icm ).   we use chemical evolution models taking into account dark matter halos and compare the results with previous models where dark matter was not considered. in particular, we examine the evolution of the abundances of some relevant heavy elements such as oxygen, magnesium and iron and conclude that models including dark matter halos and an initial mass function ( imf ) containing more massive stars than the salpeter ( 1955 ) imf, better reproduce the observed abundances of mg and fe both in the stellar populations and in the icm ( asca results ).   we also discuss the origin of gas in galaxy clusters and conclude that most of it should have a primordial origin.
an analogous model system for quantum information processing is discussed, based on classical wave optics.   the model system is applied to three examples that involve three qubits : ( _ i _ ) three - particle greenberger - horne - zeilinger entanglement, ( _ ii _ ) quantum teleportation, and ( _ iii _ ) a simple quantum error correction network.   it is found that the model system can successfully simulate most features of entanglement, but fails to simulate quantum nonlocality.   investigations of how far the classical simulation can be pushed show that _ quantum nonlocality _ is the essential ingredient of a quantum computer, even more so than entanglement.   the well known problem of exponential resources required for a classical simulation of a quantum computer, is also linked to the nonlocal nature of entanglement, rather than to the nonfactorizability of the state vector.
the possibility of observing supernova ( sn ) neutrinos through the process of coherent elastic neutrino - nucleus scattering ( cenns ) in future ton scale detectors designed primarily for direct detection of dark matter is investigated.   in particular, we focus on the possibility of distinguishing the various phases of the sn neutrino emission. the neutrino emission rates from the recent long term basel / darmstadt simulations are used to calculate the expected event rates.   the recent state - of - the - art sn simulations predict closer fluxes among different neutrino flavors and lower average energies compared to the earlier simulation models.   we find that our estimated total event rates are typically a factor of two lower than those predicted using older simulation models.   we further find that, with optimistic assumptions on the detector s time resolution ( @xmath0 10 ms ) and energy threshold ( @xmath0 0.1 kev ), the neutrinos associated with the accretion phase of the sn can in principle be demarcated out with, for example, a 10-ton xe detector, although distinguishing the neutrinos associated with the neutronization burst phase of the explosion would typically require several tens of ton detectors.   we also comment on the possibility of studying the properties of non - electron flavor neutrinos from the cenns of sn neutrinos.
wigner s little groups are subgroups of the lorentz group dictating the internal space - time symmetries of massive and massless particles.   these little groups are like o(3 ) and e(2 ) for massive and massless particles respectively.   while the geometry of the o(3 ) symmetry is familiar to us, the geometry of the flat plane can not explain the e(2)-like symmetry for massless particles.   however, the geometry of a circular cylinder can explain the symmetry with the helicity and gauge degrees of freedom.   it is shown further that the symmetry of the massless particle can be obtained as a zero - mass limit of o(3)-like symmetry for massive particles.   it is shown further that the polarization of massless neutrinos is a consequence of gauge invariance, while the symmetry of massive neutrinos is still like o(3 ).   * symmetries of massive and massless neutrinos *    y. s. kim + center for fundamental physics, university of maryland, + college park, maryland 20742, u.s.a. + e - mail : yskim@umd.edu +    presented at the international conference on hadron structure and qcd : from low to high energies ( gatchina, russia, 2016 )
the dynamics of three soft interacting particles on a ring is shown to correspond to the motion of one particle inside a soft triangular billiard.   the dynamics inside the soft billiard depends only on the _ masses ratio _ between particles and _ softness ratio _ of the particles interaction.   the transition from soft to hard interaction can be appropriately explored using potentials for which the corresponding equations of motion are well defined in the hard wall limit.   numerical examples are shown for the soft toda - like interaction and the error function.   * hard walls in billiard systems were extensively modelled by @xmath0-potentials since they allow for simple analytical relations of velocities and angles before and after the collisions with the walls.   however, equations of motion are not well defined at the collision point. to analyze the transition to soft walls, which are more realistic, it is essential to have well defined equations of motion since in general no simple analytical solutions are obtained.   the present work suggests that appropriated soft walls are those for which the forces, not the potentials, become @xmath0-functions in the limit of hard walls.   this allows for better numerical investigation of the soft - hard transition.   a general scaled hamiltonian is derived for three unequal masses interacting particles on a frictionless ring, which nicely describes this transition and shows that the dynamics occurs inside a soft triangle billiard. *
we report extensive spectroscopic and differential @xmath0-band photometric observations of the 18.4-day detached double - lined eclipsing binary lv  her ( ), which has the highest eccentricity ( @xmath1 ) among the systems with well - measured properties.   we determine the absolute masses and radii of the components to be @xmath2, @xmath3, @xmath4, and @xmath5, with fractional errors of 0.9% or better. the effective temperatures are @xmath6  k and @xmath7  k, respectively, and the overall metallicity is estimated to be  @xmath8.   a comparison with current stellar evolution models for this composition indicates an excellent fit for an age between 3.8 and 4.2  gyr, with both stars being near the middle of their main - sequence lifetimes.   full integration of the equations for tidal evolution is consistent with the high eccentricity, and suggests the stars spin axes are aligned with the orbital axis, and that their rotations should be pseudo - synchronized.   the latter prediction is not quite in agreement with the measured projected rotational velocities.
the dynamics of a bose - einstein condensate in a double - well potential are analysed in terms of transitions between energy eigenstates. by solving the time - dependent and time - independent gross - pitaevskii equation in one dimension  , we identify tunnelling resonances associated with level crossings, and determine the critical velocity that characterises the resonance.   we test the validity of a non - linear two - state model, and show that for the experimentally interesting case, where the critical velocity is large, the influence of higher - lying states is important.
in the paper we develop mathematical tools of quantile hedging in incomplete market.   those could be used for two significant applications :    1.   calculating the * optimal capital requirement imposed by solvency ii * ( directive 2009/138/ec of the european parliament and of the council ) when the market and non - market risk is present in insurance company.   + we show hot to find the minimal capital @xmath0 to provide with the one - year hedging strategy for insurance company satisfying @xmath1=0.995 $ ], where @xmath2 denotes the value of insurance company in one year time and @xmath3 is the payoff of the contract.   2.   finding a hedging strategy for derivative not using underlying but an asset with dynamics correlated or in some other way dependent ( no deterministically ) on underlying.   + the work is a genaralisation of the work of klusik and palmowski @xcite.    _   keywords : _ quantile hedging, solvency ii, capital modelling, hedging options on nontradable asset.   _ jel subject classification : _ primary g10 ; secondary g12
the radius of neutron stars can in principle be measured via the normalisation of a blackbody fitted to the x - ray spectrum during thermonuclear ( type - i ) x - ray bursts, although few previous studies have addressed the reliability of such measurements. here   we examine the apparent radius in a homogeneous sample of long, mixed h / he bursts from the low - mass x - ray binaries gs  1826@xmath024 and ks  1731@xmath026.   the measured blackbody normalisation ( proportional to the emitting area ) in these bursts is constant over a period of up to 60  s in the burst tail, even though the flux ( blackbody temperature ) decreased by a factor of 6075% ( 3040% ).   the typical rms variation in the mean normalisation from burst to burst was 35%, although a variation of 17% was found between bursts observed from gs  1826@xmath024 in two epochs.   a comparison of the time - resolved spectroscopic measurements during bursts from the two epochs shows that the normalisation evolves consistently through the burst rise and peak, but subsequently increases further in the earlier epoch bursts.   the elevated normalisation values may arise from a change in the anisotropy of the burst emission, or alternatively variations in the spectral correction factor, @xmath1, of order 10%.   since burst samples observed from systems other than gs  1826@xmath024 are more heterogeneous, we expect that systematic uncertainties of at least 10% are likely to apply generally to measurements of neutron - star radii, unless the effects described here can be corrected for.
vitruv is a second generation spectro - imager for the prima enabled very large telescope interferometer. by combining simultaneously up to 8 telescopes vitruv   makes the vlti up to 6 times more efficient.   this operational gain allows two novel scientific methodologies : 1 ) massive surveys of sizes ; 2 ) routine interferometric imaging.   the science cases presented concentrate on the qualitatively new routine interferometric imaging methodology.   the science cases are not exhaustive but complementary to the prima reference mission.   the focus is on : a ) the close environment of young stars probing for the initial conditions of planet formation and disk evolution ; b ) the surfaces of stars tackling dynamos, activity, pulsation, mass - loss and evolution ; c ) revealing the origin of the extraordinary morphologies of planetary nebulae and related stars ; d ) studying the accretion - ejection structures of stellar black - holes ( microquasars ) in our galaxy ; e ) unveiling the different interacting components ( torus, jets, blrs ) of active galactic nuclei ; and f ) probing the environment of nearby supermassive black - holes and relativistic effects in the galactic center black - hole.
a first - principles calculation of the impurity screening in si and ge nanocrystals is presented.   we show that isocoric screening gives results in agreement with both the linear response and the point - charge approximations.   based on the present _ ab initio _ results, and by comparison with previous calculations, we propose a physical real - space interpretation of the several contributions to the screening. combining the thomas - fermi theory and simple electrostatics, we show that it is possible to construct a model screening function that has the merit of being of simple physical interpretation.   the main point upon which the model is based is that, up to distances of the order of a bond length from the perturbation, the charge response does not depend on the nanocrystal size.   we show in a very clear way that the link between the screening at the nanoscale and in the bulk is given by the surface polarization. a detailed discussion is devoted to the importance of local field effects in the screening.   our first - principles calculations and the thomas - fermi theory clearly show that in si and ge nanocrystals, local field effects are dominated by surface polarization, which causes a reduction of the screening in going from the bulk down to the nanoscale.   finally, the model screening function is compared with recent state - of - the - art _ ab initio _ calculations and tested with impurity activation energies.
adding a scalar triplet to the standard model is one of the simplest ways of giving mass to neutrinos, providing at the same time a mechanism to stabilize the theory s vacuum. in this paper, we revisit these aspects of the type - ii seesaw model pointing out that the bounded - from - below conditions for the scalar potential in use in the literature are not correct.   we discuss some scenarios where the correction can be significant and sketch the typical scalar boson profile expected by consistency.   ahep group, instituto de fsica corpuscular, c.s.i.c./universitat de valncia + edificio institutos de investigacin, apartado 22085, e46071 valencia, spain
the geometric phase induced in an auxiliary qubit by a many - body system is calculated and discussed.   two kinds of coupling between the auxiliary qubit and the many - body system are considered, which lead to dephasing and dissipation in the qubit, respectively. as an example, we consider the xy spin - chain dephasingly couple to a qubit, the geometric phase induced in the qubit is presented and discussed.   the results show that the geometric phase might be used to signal the critical points of the many - body system, and it tends to zero with the parameters of the many - body system going away from the critical points.
one finding of cognitive research is that people do not automatically acquire usable knowledge by spending lots of time on task. because students knowledge hierarchy is more fragmented, `` knowledge chunks ''   are smaller than those of experts.   the limited capacity of short term memory makes the cognitive load high during problem solving tasks, leaving few cognitive resources available for meta - cognition.   the abstract nature of the laws of physics and the chain of reasoning required to draw meaningful inferences makes these issues critical. in order to help students  , it is crucial to consider the difficulty of a problem from the perspective of students.   we are developing and evaluating interactive problem - solving tutorials to help students in the introductory physics courses learn effective problem - solving strategies while solidifying physics concepts.   the self - paced tutorials can provide guidance and support for a variety of problem solving techniques, and opportunity for knowledge and skill acquisition.   address = department of physics and astronomy, university of pittsburgh, pittsburgh, pennsylvania, 15260
we use pythia event generator to simulate the process of muon pair production in antiproton scattering upon the proton target at the energy of the antiproton equal to @xmath0, which may be one of the energies for the future panda ( gsi, darmstadt ) experiment operation.
the investigation of the non - linearity of the leavitt law is a topic that began more than seven decades ago, when some of the studies in this field found that the leavitt law has a break at about ten days.   + the goal of this work is to investigate a possible statistical cause of this non - linearity. by applying linear regressions to ogle - ii and ogle - iv data, we find that, in order to obtain the leavitt law by using linear regression, robust techniques to deal with influential points and/or outliers are needed instead of the ordinary least - squares regression traditionally used. in particular, by using @xmath0- and @xmath1-regressions we establish firmly and without doubts the linearity of the leavitt law in the large magellanic cloud, without rejecting or excluding cepheid data from the analysis.   this implies that light curves of cepheids suggesting blending, bumps, eclipses or period changes, do not affect the leavitt law for this galaxy. for the smc, including this kind of cepheids, it is not possible to find an adequate model, probably due to the geometry of the galaxy. in that case, a possible influence of these stars could exist.
the last few months have seen the measurements of the radial velocities of all of the dwarf spheroidal companions to the andromeda galaxy ( m31 ) using the spectrographs ( hires and lris ) on the _ keck telescope_. this paper summarises the data on the radial velocities and distances for all the companion galaxies and presents new dynamical modelling to estimate the mass of extended halo of m31.   the best fit values for the total mass of m31 are @xmath0, depending on the details of the modelling.   the mass estimate is accompanied by considerable uncertainty caused by the smallness of the dataset ; for example, the upper bound on the total mass is @xmath1, while the lower bound is @xmath2.   these values are less than the most recent estimates of the most likely mass of the milky way halo.   bearing in mind all the uncertainties, a fair conclusion is that the m31 halo is roughly as massive as that of the milky way halo.   there is no dynamical evidence for the widely held belief that m31 is more massive   it may even be less massive.   = cmcsc10    # 1#2 # 1to 0pt#1
the euclidean plane is certainly the simplest example of real hilbert space.   viewed as a space of quantum states, it can be used as a nice introductive example in teaching quantum formalism.   the pure states form the unit circle ( actually one half of it ), the mixed states form the unit disk ( actually one half of it ), and rotations in the plane rule time evolution through a majorana - like equation involving only real quantities.   the set of pure states or the set of mixed states at fixed `` temperature '' solve the identity and they are used for the integral quantization of functions on the unit circle and to give a semi - classical portrait of quantum observables.   interesting probabilistic aspects are developed. since the tensor product of two planes, their direct sum, their cartesian product, are isomorphic ( @xmath0 is the unique solution to @xmath1 ), and they are also isomorphic to @xmath2, and to the quaternion field @xmath3 ( as a vector space )  , we describe an interesting relation between entanglement of real states, one - half spin cat states, and unit - norm quaternions which form the group su@xmath4.   finally, we explain the most general form of the hamiltonian in the real plane by considering the integral quantization of a magnetic - like interaction potential viewed as a classical observable on the unit 2-sphere.
the structural and electronic properties of gold decorated si(335 ) surface are studied by means of density - functional calculations.   the resulting structural model indicates that the au atoms substitute some of the si atoms in the middle of the terrace in the surface layer.   calculated electronic band structure near the fermi energy features two metallic bands, one coming from the step edge si atoms and the other one having its origin in hybridization between the au and neighboring si atoms in the middle of the terrace.   the obtained electronic bands remain in good agreement with photoemission data.   _ keywords : _ density functional calculations ; silicon ; high index surfaces ; surface structure ; photoelectron spectroscopy
the strong coupling limit of a quantum system is in general quite complicated, but in some cases a great simplification occurs : the strongly coupled limit is equivalent to the weakly coupled limit of some other system. in string theory conjectures of this type   go back several years, but only in the past year and a half has it been understood to be a general principle applying to all string theories.   this has improved our understanding of string dynamics, including quantum gravity, in many new and sometimes surprising ways.   i describe these developments and put them in the context of the search for the unified theory of particle physics and gravity.   epsf.tex    3.7 in    * string duality *    * a colloquium *    * joseph polchinski *    institute for theoretical physics    university of california    santa barbara, ca  93106 - 4030    e - mail : joep@itp.ucsb.edu
the relation between angular diameter distance and redshift ( @xmath0@xmath1 relation ) in a spherically symmetric dust  shell universe is studied.   this model has large inhomogeneities of matter distribution on small scales.   we have discovered that the relation agrees with that of an appropriate friedmann   lematre(fl ) model if we set a `` homogeneous '' expansion law and a `` homogeneous '' averaged density field.   this will support the averaging hypothesis that a universe looks like a fl model in spite of small - scale fluctuations of density field, if its averaged density field is homogeneous on large scales.   @ @.2326ex # 1^to-1.4@-@@     +  spherically symmetric dust   shell universe  +    norimasa sugiura, ken - ichi nakao and tomohiro harada + _ department of physics,  kyoto university, sakyo - ku, kyoto 606 - 8502, japan _
many important techniques for investigating the properties of extragalactic radio sources, such as spectral - index and rotation - measure mapping, involve the comparison of images at two or more frequencies. in the case of radio interferometric data, this can be done by comparing the clean maps obtained at the different frequencies.   however, intrinsic differences in images due to the frequency dependence of the radio emission can be distorted by additional differences that arise due to source variability ( if the data to be compared is obtained at different times ), image misalignment, and the frequency dependence of the sensitivity to weak emission and the angular resolution provided by the observations ( the resolution of an interferometer depends on the lengths of its baselines in units of the observing wavelength ).   these effects must be corrected for as best as possible before multi - frequency data comparison techniques can be applied.   we consider the origins for the afore - mentioned factors, outline the standard techniques used to overcome these difficulties, and describe in detail a technique developed by us, based on the cross - correlation technique widely used in other fields, to correct for misalignments between maps at different frequencies.   
the endpoint of black hole evaporation is a very intriguing problem of modern physics.   based on einstein - dilaton - gauss - bonnet four dimensional string gravity model we show that black holes do not disappear and should become relics at the end of the evaporation process.   the possibility of experimental detection of such remnant black holes is investigated.   if they really exist, these objects could be a considerable part of the non baryonic dark matter in our universe.
we present 83 new galaxy radial velocities in the field of 18 apm clusters with redshifts between 0.06 and 0.13.   the clusters have abell identifications and the galaxies were selected within 0.75 h@xmath0mpc in projection from their centers.   we derive new cluster velocity dispersions for 13 clusters using our data and published radial velocities.   we analyze correlations between cluster velocity dispersions and cluster richness counts as defined in abell and apm catalogs.   the correlations show a statistically significant trend although with a large scatter suggesting that richness is a poor estimator of cluster mass irrespectively of cluster selection criteria and richness definition.   we find systematically lower velocity dispersions in the sample of abell clusters that do not fulfill apm cluster selection criteria suggesting artificially higher abell richness counts due to contamination by projection effects in this subsample.   galaxies : clustering  galaxies : dynamics  cosmology : observations  cosmology : theory.
we show that radiative feedback due to reionization has a pronounced effect on the extent of mechanical feedback due to galactic outflows.   the photoionization of the intergalactic medium ( igm ) suppresses low - mass galaxy formation by photoheating the gas and limiting atomic line cooling.   the number of low - mass galaxies is central for the enrichment of the igm as these objects have the capacity to enrich a significant fraction ( by volume ) of the universe.   we use a modified version of our galactic outflow model, combined with a simple criterion for suppression, to investigate the potential impact upon the igm.   we find that this suppression strongly reduces the enrichment of the igm and is sensitive to the reionization history.   we also investigate the contribution of halos of different masses with varying degrees of suppression.
we present the design and commissioning of a new multiplicity veto for the  detector, a fixed - target spectrometer originally designed to study the physics of @xmath0 mesons in proton - nucleus interactions.   the  trigger is a message - driven multi - level track trigger.   the first level trigger ( flt ) consists of custom - made electronics, and the higher trigger levels are implemented as pc farms.   the multiplicity veto has been designed to reject high - multiplicity events before they enter the trigger chain.   a veto signal is generated based on the comparison of the number of photons in part of the   ring - imaging erenkov counter ( rich ) with a programmable threshold.   the rich multiplicity veto  is a modular system.   first the hits in 256 detector channels are summed by base sum cards ( bsc ), then fed sum cards ( fsc ) sum the subtotals of up to eight bscs.   finally the veto board ( vb ) takes the veto decision based on the sum of up to 14 fscs.   the rich multiplicity veto  has been successfully installed and commissioned in.   the measured veto efficiency is @xmath1, and the system is used in the routine data - taking of the  experiment.    * si-2003 - 1 *    poster presented at the ieee nuclear science symposium 2002, +    norfolk, virginia,   november 1214, 2002    this work was supported by the german bundesministerium fr    bildung und forschung ( bmbf ) under the contract number 5hb1pea/7.
we present a variational study of pseudo - spin @xmath0 bose gases in a harmonic trap with weak 3d spin - orbit coupling of @xmath1 type.   this spin - orbit coupling mixes states with different parities, which inspires us to approximate the single particle state with the eigenstates of the total angular momentum, i.e. superposition of harmonic @xmath2-wave and @xmath3-wave states.   as the time reversal symmetry is protected by two - body interaction, we set the variational order parameter as the combination of two mutually time reversal symmetric eigenstates of the total angular momentum.   the variational results essentially reproduce the 3d skyrmion - like ground state recently identified by kawakami _   et al._. we show that these skyrmion - like ground states emerging in this model are primarily caused by @xmath3 wave spatial mode involving in the variational order parameter that drives two spin components spatially separated.   we find the ground state of this system falls into two phases with different density distribution symmetries depending on the relative magnitude of intraspecies and interspecies interaction : phase i has parity symmetric and axisymmetric density distributions, while phase ii is featured with special joint symmetries of discrete rotational and time reversal symmetry. with the increasing interaction strength   the transition occurs between two phases with distinct density distributions, while the topological 3d skyrmion - like spin texture is symmetry protected.
we extensively study the growing behavior of the energy and the pressure components depending on the space - time rapidity in the framework of the glasma, which describes the early - time dynamics in the ultra - relativistic heavy - ion collisions.   we simulate the glasma solving the classical equations of motion in the su(2 ) yang - mills theory and systematically investigate the dependence of the glasma instability on the model parameters.   we have checked that the transverse and longitudinal grid sizes in our simulation are large enough to handle cutoff effects under control. by comparing the numerical results from several initial conditions with different magnitudes of instability seed and also those with different wave - numbers for rapidity fluctuations, we clearly see that unstable modes dominantly grow up in the linear regime and we also confirm non - linear effects in the time evolution.   to extract more detailed information on the evolving glasma, we decompose the energy into the components in terms of rapidity wave - numbers.   we observe an energy flow from low wave - number modes into higher wave - number modes due to non - linearity in the equations of motion.   we find that the energy spectrum approaches an asymptotic scaling that is consistent with kolmogorov s power - law form even in the expanding system of the glasma.    and    color glass condensate, glasma, relativistic heavy - ion collision, instability, kolmogorov spectrum
we present evidence for a substantial overdensity of stars in the direction of the constellations of hercules and aquila.   the cloud is centered at a galactic longitude of @xmath0 and extends above and below the galactic plane by at least @xmath1.   given its off - centeredness and height, it is unlikely that the hercules - aquila cloud is related to the bulge or thick disk.   more likely, this is a new structural component of the galaxy that passes through the disk.   the cloud stretches @xmath2 in longitude.   its heliocentric distance lies between 10 and 20 kpc so that the extent of the cloud in projection is @xmath3 kpc by @xmath4 kpc.   it has an absolute magnitude of @xmath5 and its stellar population appears to be comparable to, but somewhat more metal - rich than, m92.
full potential spin - polarized self - consistent electronic structure calculations have been performed on lab@xmath0, eub@xmath0 and ybb@xmath0 using linear muffin - tin orbital method.   the electronic structure of eub@xmath0 shows a small overlap near the fermi level.   this is in disagreement with the recent arpes study.   the reflectivity spectrum shows a plasma resonance at about 0.3 ev in eub@xmath0.   absorption starts at about 1.5 ev and it is due to 4@xmath1 to 5@xmath2 transition.   both these features are reflected in the magneto - optical kerr spectrum. at 0.3 ev  , there is a rotation of + 8@xmath3 to -10@xmath3 and at 1.5 ev, a rotation of about 0.5@xmath3 occurs.   the reasonable agreement with moke experiment implies that the inclusion of drude correction is absolutely essential for the treatment of eub@xmath0.
the magneto - conductivity of a single graphene layer where the electrons are described by the dirac hamiltonian weakly modulated by a periodic potential is calculated.   it is shown that weiss oscillations periodic in the inverse magnetic field appear, that are more pronounced and less damped with the increment of temperature as compared with the same oscillations in a typical two - dimensional electron system with a standard parabolic energy spectrum.
the distribution, @xmath0, of the interval sizes, @xmath1, between clusters of persistent sites in the dynamical evolution of the one - dimensional @xmath2-state potts model is studied using a combination of numerical simulations, scaling arguments, and exact analysis.   it is shown to have the scaling form @xmath3, with @xmath4, where @xmath5 is the persistence exponent which describes the fraction, @xmath6, of sites which have not changed their state up to time @xmath7. when @xmath8, the scaling length @xmath9 for the interval - size distribution is larger than the coarsening length scale @xmath10 that characterizes spatial correlations of the potts variables.    2
this paper deals with the structural analysis problem of dynamic lumped process high - index dae models.   we consider two methods for index reduction of such models by differentiation : pryce s method and the symbolic differential elimination algorithm rifsimp.   discussion and comparison of these methods are given via a class of fundamental process simulation examples.   in particular, the efficiency of the pryce method is illustrated as a function of the number of tanks in process design.   algebraic equations, structural analysis, symbolic differential elimination, fast prolongation, linear programming problem
we use sample of 813 lyman - break galaxies ( lbgs ) with @xmath0 to perform a detailed analysis of the redshift - space ( @xmath1-space ) distortions in their clustering pattern and from them derive confidence levels in the @xmath2 $ ] plane.   we model the @xmath1-space distortions in the shape of the correlation function measured in orthogonal directions, @xmath3.   this modeling requires an accurate description of the real - space correlation function to be given as an input. from the projection of @xmath3 in the angular direction, @xmath4  , we derive the best fitting amplitude and slope for the lbg real - space correlation function : @xmath5 and @xmath6 ( @xmath7 ).   a comparison between the shape of @xmath8 and @xmath4 suggests that @xmath9 deviates from a simple power - law model, with a break at @xmath10.   this model is consistent with the observed projected correlation function.   however, due to the limited size of the fields used, the @xmath4 results are limited to @xmath11. assuming this double power - law model, and by analysing the shape distortions in @xmath3  , we find the following constraints : @xmath12, @xmath13.   combining these results with orthogonal constraints from linear evolution of density perturbations, we find that @xmath14, @xmath15.       surveys - galaxies, galaxies : general, large - scale structure of universe, cosmology : observations
in thin films of smectic - c liquid crystals, localized regions containing additional smectic layers form circular inclusions that carry a topological charge.   such inclusions nucleate a companion topological defect.   these inclusion - defect pairs are modeled as topological dipoles within the context of a one - coupling constant approximation to the @xmath0 frank free energy.   deviations of the dipole direction from a preferred orientation cause the dipoles to acquire a logarithmic charge.   thermal fluctuations of the dipole direction are calculated and found to be large, scaling as the logarithm of the system size.   in addition to dipole - dipole interactions arising from the topological charges, we also find that the thermal fluctuations of the dipole directions are coupled through a preference for global charge neutrality of the logarithmic charges.   psfig    corresponding author : david pettey + department of physics and astronomy + university of pennsylvania + philadelphia, pa 19104
disordered biopolymer gels have striking mechanical properties including strong nonlinearities. in the case of athermal gels ( such as collagen - i )   the nonlinearity has long been associated with a crossover from a bending dominated to a stretching dominated regime of elasticity.   the physics of this crossover is related to the existence of a central - force isostatic point and to the fact that for most gels the bending modulus is small.   this crossover induces scaling behavior for the elastic moduli.   in particular, for linear elasticity such a scaling law has been demonstrated . in this work   we generalize the scaling to the nonlinear regime with a two - parameter scaling law involving three critical exponents.   we test the scaling law numerically for two disordered lattice models, and find a good scaling collapse for the shear modulus in both the linear and nonlinear regimes.   we compute all the critical exponents for the two lattice models and discuss the applicability of our results to real systems.
the charge of an ideal parallel capacitor leads to the resolution of the wave equation for the electric field with prescribed initial conditions and boundary constraints. independently of the capacitor s shape and the applied voltage,   none of the corresponding solutions is compatible with the full set of maxwell s equations.   the paradoxical situation persists even by weakening boundary conditions, resulting in the impossibility to describe a trivial phenomenon such as the capacitor s charging process, by means of the standard maxwellian theory.   @xmath0dipartimento di fisica, informatica e matematica    universit di modena e reggio emilia, via campi 213/b, 41125 modena ( italy )    keywords : maxwell equations, wave equation, capacitor, paradox.   pacs : 02.30.jr, 41.20.jb
we present rxte observations of two recently identified massive x - ray binaries.   rx j0440.9   + 4431/bsd 24491 and rx j1037.5564/ls 1698 are confirmed as accreting be / x - ray systems following the discovery of x - ray pulsations, with barycentric pulse periods of 202.5@xmath00.5 s and 860@xmath02 s respectively.   the x - ray spectral analysis shows that the energy spectra of the pulsars can be represented by a power - law, modified at low energy by an absorption component and at high energy by a cut - off.   very weak fe lines may be present.   both sources appear to display a low cut - off energy when compared to typical x - ray pulsars, low x - ray variability ( factor of @xmath110 ), and no dependence of the x - ray spectrum with energy. given the similarity of these x - ray properties with those of the other persistent bexrb pulsars, 4u0352 + 309/x per and rx j0146.9 + 6121/ls i + 61 235, we suggest that rx j0440.9 + 4431/bsd 24491 and rx j1037.5564/ls 1698 are also members of this subclass.   stars : emission - line, be - star : x - rays : stars - stars : pulsars
a method is formulated for the description of lambda hypernuclei in the framework of the unitary - model - operator approach ( umoa ).   the method is applied to @xmath0o.   a lambda - nucleon effective interaction is derived, taking the coupling of the sigma - nucleon channel into account.   the lambda single - particle energies are calculated for the 0@xmath1, 0@xmath2 and 0@xmath3 states employing the nijmegen soft - core ( nsc ), jlich model -  ( j ) and model - b ( jb ) hyperon - nucleon potentials.    unitary model operator approach ; hypernuclei ; lambda single particle energy ; effective interaction ; nijmegen potential ; jlich potential
the microscopic mechanisms controlling heterogeneous ice nucleation are complex and remain poorly understood. although good ice nucleators are generally believed to match ice lattice and to bind water, counter examples are often identified. here   we show, by advanced molecular simulations, that the heterogeneous nucleation of ice on graphitic surface is controlled by the coupling of surface crystallinity and surface hydrophilicity.   molecular level analysis reveals that the crystalline graphitic lattice with an appropriate hydrophilicity may indeed template ice basal plane by forming a strained ice layer, thus significantly enhancing its ice nucleation efficiency.   remarkably, the templating effect is found to transit from within the first contact layer of water to the second as the hydrophilicity increases, yielding an oscillating distinction between the crystalline and amorphous graphitic surfaces in their ice nucleation efficiencies.   our study sheds new light on the long - standing question of what constitutes a good ice nucleator.
vdb0-b195d is a massive, blue star cluster in m31.   it was observed as part of the beijing - arizona - taiwan - connecticut ( batc ) multicolor sky survey using 15 intermediate - band filters covering a wavelength range of 300010,000 .   based on aperture photometry, we obtain its spectral - energy distribution ( sed ) as defined by the 15 batc filters.   we apply previously established relations between the batc intermediate - band and the johnson - cousins @xmath0 broad - band systems to convert our batc photometry to the standard system.   a detailed comparison shows that our newly derived @xmath1 magnitudes are fully consistent with previous results, while our new @xmath2 magnitude agrees to within @xmath3.   in addition, we determine the cluster s age and mass by comparing its sed ( from 3000 to 20,000, comprising photometric data in the 15 batc intermediate bands, optical broad - band @xmath4, and 2mass near - infrared @xmath5 data ) with theoretical stellar population synthesis models, resulting in age and mass determinations of @xmath6  myr and @xmath7, respectively.   this age and mass confirms previous suggestions that vdb0-b195d is a young massive cluster in m31.
recently, @xcite observed that the uv transit of wasp-12b showed an early ingress compared to the optical transit.   we suggest that the resulting early ingress is caused by a bow shock ahead of the planetary orbital motion. in this letter   we investigate the conditions that might lead to the formation of such a bow shock.   we consider two scenarios : ( 1 ) the stellar magnetic field is strong enough to confine the hot coronal plasma out to the planetary orbit and ( 2 ) the stellar magnetic field is unable to confine the plasma, which escapes in a wind. in both cases,   a shock capable of compressing plasma to the observed densities will form around the planet for plasma temperatures @xmath0k. in the confined case  , the shock always forms directly ahead of the planet, but in the wind case the shock orientation depends on the wind speed and hence on the plasma temperature. for higher wind temperatures, the shock forms closer to the line of centers between the planet and the star.   we conclude that shock formation leading to an observable early uv ingress is likely to be a common feature of transiting systems and may prove to be a useful tool in setting limits on planetary magnetic field strengths @xmath1. in the case of wasp-12b, we derive an upper limit of about @xmath2  g.
we develop a mathematical model for sap exudation in a maple tree that is based on a purely physical mechanism for internal pressure generation in trees in the leafless state.   there has been a long - standing controversy in the tree physiology literature over precisely what mechanism drives sap exudation, and we aim to cast light on this issue. our model is based on the work of milburn and omalley [ _ can.   j.  bot.   _, ( 10):21012106, 1984 ] who hypothesized that elevated sap pressures derive from compressed gas that is trapped within certain wood cells and subsequently released when frozen sap thaws in the spring.   we also incorporate the extension of tyree [ in _ tree  sap _, pp.  3745, eds.   m.  terazawa et al.  , hokkaido univ.  press, 1995 ] who argued that gas bubbles are prevented from dissolving because of osmotic pressure that derives from differences in sap sugar concentrations and the selective permeability of cell walls.   we derive a system of differential - algebraic equations based on conservation principles that is used to test the validity of the milburn  omalley hypothesis and also to determine the extent to which osmosis is required.   this work represents the first attempt to derive a detailed mathematical model of sap exudation at the micro - scale.   sap transport, multiphase flow, phase change, stefan problem, gas dissolution, osmosis.    35r37,   76m12,   76t30,   80a22,   92c80.
the in - plane resistivity of the high - temperature oxide superconductor la@xmath0sr@xmath1cuo@xmath2  shows a strong growth of a contribution linear in temperature as the doping is reduced in the overdoped region toward optimal.   this linear term is a signature of non - fermi liquid behavior.   we find that the appearance of a linear term in the resistivity can arise in a semiclassical boltzmann transport theory which uses renormalized quasiparticle scattering rates derived in a functional renormalization group calculation and an empirical band structure fitted to angle - resolved photoemission spectroscopy data on lsco.   the linearized boltzmann equation is solved numerically by discretizing the brillouin zone in a way that fits best to the fermi surface geometry.   the main trends in the development of the anomalous temperature dependence are well reproduced.   there is a substantial underestimation of the magnitude of the resistivity which is expected in view of the moderate to weak values we chose for the onsite repulsion to stay within the one - loop renormalization group approximation.   the analysis was extended to the seebeck coefficient with similar agreement with the main trends in the data.   this article is accepted for publication ( jan.   2nd, 2013 ) : phys.   rev.   b * 87 *, 035129 ( 2013 ) + http://link.aps.org/doi/10.1103/physrevb.87.035129
we analyze uv observations with faust of four sky fields in the general direction of the fourth galactic quadrant, in which we detect 777 uv sources.   this is @xmath050% more than detected originally by bowyer ( 1995 ).   we discuss the source detection process and the identification of uv sources with optical counterparts.   for the first time in this project we use ground - based objective - prism information for two of the fields, to select the best - matching optical objects with which to identify the uv sources. using this, and correlations with existing catalogs, we present reliable identifications for @xmath075% of the sources.   most of the remaining sources have assigned optical counterparts, but lacking additional information we offer only plausible identification.   we discuss the types of objects found, and compare the observed population with predictions of our uv galaxy model.   # 1#2#3#4#5#6#7    to#2   ''' ''
using a combination of keck spectroscopy and near - infrared imaging, we investigate the k - band and stellar mass tully - fisher relation for 101 disk galaxies at 0.2 @xmath01.2, with the goal of placing the first observational constraints on the assembly history of halo and stellar mass.   our main result is a lack of evolution in either the k - band or stellar mass tully - fisher relation from @xmath1.   furthermore, although our sample is not statistically complete, we consider it suitable for an initial investigation of how the fraction of total mass that has condensed into stars is distributed with both redshift and total halo mass.   we calculate stellar masses from optical and near - infrared photometry and total masses from maximum rotational velocities and disk scale lengths, utilizing a range of model relationships derived analytically and from simulations.   we find that the stellar / total mass distribution and stellar - mass tully - fisher relation for @xmath20.7 disks is similar to that at lower redshift, suggesting that baryonic mass is accreted by disks along with dark matter at @xmath3, and that disk galaxy formation at @xmath3 is hierarchical in nature.   we briefly discuss the evolutionary trends expected in conventional structure formation models and the implications of extending such a study to much larger samples.
quantum fluctuations in time - dependent, harmonically - trapped bose - einstein condensates are studied within bogoliubov theory.   an eigenmode expansion of the linear field operators permits the diagonalization of the bogoliubov - de gennes equation for a stationary condensate.   when trap frequency or interaction strength are varied, the inhomogeneity of the background gives rise to off - diagonal coupling terms between different modes.   this coupling is negligible for low energies, i.e., in the hydrodynamic regime, and an effective space - time metric can be introduced.   the influence of the inter - mode coupling will be demonstrated in an example, where i calculate the quasi - particle number for a quasi - one - dimensional bose - einstein condensate subject to an exponential sweep of interaction strength and trap frequency.
we use a collection of 14 well - measured neutron star masses to strengthen the case that a substantial fraction of these neutron stars was formed via electron - capture supernovae ( sne ) as opposed to fe - core collapse sne.   the e - capture sne are characterized by lower resultant gravitational masses and smaller natal kicks, leading to lower orbital eccentricities when the e - capture sn has led to the formation of the second neutron star in a binary system.   based on the measured masses and eccentricities, we identify four neutron stars, which have a mean post - collapse gravitational mass of @xmath0@xmath1 @xmath2, as the product of e - capture sne.   we associate the remaining ten neutron stars, which have a mean mass of @xmath01.35 @xmath2, with fe - core collapse sne.   if the e - capture supernova occurs during the formation of the first neutron star, then this should substantially increase the formation probability for double neutron stars, given that more systems will remain bound with the smaller kicks.   however, this does not appear to be the case for any of the observed systems, and we discuss possible reasons for this.
we analyze the dynamics of a luttinger model following a quench in the electron - electron interaction strength, where the change in the interaction strength occurs over a finite time scale @xmath0.   we study the loschmidt echo ( the overlap between the initial and final state ) as a function of time, both numerically and within a perturbation scheme, treating the change in the interaction strength as a small parameter, for all @xmath0.   we derive the corrections appearing in, a. ) the loschmidt echo for a finite quench duration @xmath0, b. ) the scaling of the echo following a sudden ( @xmath1 ) quench, and c. ) the scaling of the echo after an adiabatic ( @xmath2 ) quench.   we study in detail, the limiting cases of the echo in the early time and infinite time limit, and provide scaling arguments to understand these in a general context.   we also show that our perturbative results are in good agreement with the exact numerical ones.
we report here measurements on a dark magneto - optical trap ( dmot ) of @xmath0rb atoms using an optical nanofibre ( onf ) with a waist of @xmath1  1 @xmath2 m.   the dmot is created using a doughnut - shaped repump beam along with a depump beam for efficient transfer of cold atoms from the bright hyperfine ground state ( @xmath3 ) into the dark hyperfine ground state ( @xmath4 ).   the fluorescence from the cold @xmath0rb atoms of the dmot is detected by coupling it into the fibre - guided modes of the onf.   the measured fractional population of cold atoms in the bright hyperfine ground state ( @xmath5 ) is as low as @xmath10.04.   the dependence of loading rate of dmot on cooling laser intensity is investigated and also compared with the loading rate of a bright - mot ( bmot ).   this work lays the foundation for the use of an onf for probing of a small number of atoms in an optically - dense cold atomic cloud.   _ keywords _ : laser - cooling, dark mot, rubidium, tapered optical fibre, optical nanofibre, atom cloud density
we present first results of a survey of the leo i group at 10 mpc for @xmath0 dwarf galaxies.   this is part of a larger program to measure the faint end of the galaxy luminosity function in nearby poor groups.   our method is optimized to find local - group - like dwarfs down to dwarf spheroidal surface brighnesses, but we also find very large lsb dwarfs in leo i with no local group counterpart.   a preliminary measurement of the luminosity function yields a slope consistent with that measured in the local group.   ps.   @plainmkbothoddheadoddfoot``dwarf galaxies and their environment '' ; international conference in bad honnef, germany, 23 - 27 january 2001evenheadevenfootoddfoot
the present work discusses motion of neutral and charged particles in reissner - nordstrm spacetime.   the constant energy paths are derived in a variational principle framework using the jacobi metric which is parameterized by conserved particle energy.   of particular interest is the case of particle charge and reissner - nordstrm black hole charge being of same sign since this leads to a clash of opposing forces - gravitational ( attractive ) and coulomb ( repulsive ).   praloy das, ripon sk and subir ghosh +   +
we review recent theoretical results on generalized parton distributions ( gpds ) of nuclei, emphasizing the following three roles of nuclear gpds : ( i ) complementarity to free proton gpds, ( ii ) the enhancement of traditional nuclear effects such as nuclear binding, emc effect, nuclear shadowing, and ( iii ) an access to novel nuclear effects such as medium modifications of bound nucleons.   address = theory center, thomas jefferson national accelerator facility, newport news, va 23606, usa, email=vguzey@jlab.org
solar oscillations are expected to be excited by turbulent flows in the intergranular lanes near the solar surface.   time series recorded by the imax instrument aboard the sunrise observatory reveal solar oscillations at high resolution, which allow studying the properties of oscillations with short wavelengths.   we analyze two times series with synchronous recordings of doppler velocity and continuum intensity images with durations of 32min and 23min, resp., recorded close to the disk center of the sun to study the propagation and excitation of solar acoustic oscillations. in the doppler velocity data, both the standing acoustic waves and   the short - lived, high - degree running waves are visible.   the standing waves are visible as temporary enhancements of the amplitudes of the large - scale velocity field due to the stochastic superposition of the acoustic waves.   we focus on the high - degree small - scale waves by suitable filtering in the fourier domain. investigating the propagation and excitation of @xmath0- and @xmath1-modes with wave numbers   @xmath21/mm we find that also exploding granules contribute to the excitation of solar @xmath3-modes in addition to the contribution of intergranular lanes.
we introduce coarse - grained hydrodynamic equations of motion for diffusion - annihilation system with a power - law long - range interaction. by taking into account fluctuations of the conserved order parameter - charge density   - we derive an analytically solvable approximation for the nonconserved order parameter - total particle density.   asymptotic solutions are obtained for the case of random gaussian initial conditions and for system dimensionality @xmath0.   large - t, intermediate - t and small - t asymptotics were calculated and compared with existing scaling theories, exact results and simulation data.
topological matter is a popular topic in both condensed matter and cold atom research. in the past decades,   a variety of models have been identified with fascinating topological features.   some, but not all, of the models can be found in materials. as a fully controllable system,   cold atoms trapped in optical lattices provide an ideal platform to simulate and realize these topological models. here   we present a proposal for synthesizing topological models in cold atoms based on a one - dimensional ( 1d ) spin - dependent optical lattice potential. in our system, features such as staggered tunneling, staggered zeeman field, nearest - neighbor interaction, beyond - near - neighbor tunneling, etc. can be readily realized.   they underlie the emergence of various topological phases.   our proposal can be realized with current technology and hence has potential applications in quantum simulation of topological matter.
the gaseous proportional counter is a device that can be used to detect ionizing radiation  . these devices can be as simple as a cylindrical cathode and a very thin anode wire centered along its axis. by applying a high voltage, a strong electric field   is generated close to the anode wire.   ion - pairs, generated by passing ionizing radiation, create avalanches once they drift into the strong electric field region near the anode.   the electrical charges created by the avalanche generate an observable signal which is proportional to the energy loss of the incoming radiation.   we discuss the construction of such a device.   our detector was built from an ordinary aluminium beverage can and uses a common electric wire strand as the anode.   the construction of this detector offers students at universities or technically oriented high schools a detailed understanding of the design and operation of gaseous radiation detectors.   the equipment required to complete the project should be available at most institutions.
we investigate the ballistic motion of electrons in iii - v semiconductor quantum wells with rashba spin - orbit coupling in a perpendicular magnetic field. taking into account the full quantum dynamics of the problem  , we explore the modifications of classical cyclotron orbits due to spin - orbit interaction. as a result, for electron energies comparable with the cyclotron energy the dynamics are particularly rich and not adequately described by semiclassical approximations.   our study is complementary to previous semiclassical approaches concentrating on the regime of weaker fields.
this paper discusses skyrmions on the @xmath0-sphere coupled to fermions.   the resulting dirac equation commutes with a generalized angular momentum @xmath1. for @xmath2 the dirac equation   can be solved explicitly for a constant skyrme configuration and also for a @xmath3 symmetric hedgehog configuration.   we discuss how the spectrum changes due to the presence of a non - trivial winding number, and also consider more general skyrme configurations numerically.   pages, 6 figures
the diamond norm measures the distance between two quantum channels. from an operational vewpoint, this norm measures how well we can distinguish between two channels by applying them to input states of arbitrarily large dimensions. in this paper, we show that the diamond norm can be conveniently and in a physically transparent way computed by means of a monte - carlo algorithm based on the fano representation of quantum states and quantum operations.   the effectiveness of this algorithm is illustrated for several single - qubit quantum channels.
we present large - scale density - functional theory ( dft ) calculations and temperature programmed desorption measurements to characterize the structural, energetic and vibrational properties of the functionalized molecular switch @xmath0-tetra-_tert_-butyl - azobenzene ( tba ) adsorbed at au(111 ).   particular emphasis is placed on exploring the accuracy of the semi - empirical dispersion correction approach to semi - local dft ( dft - d ) in accounting for the substantial van der waals component in the surface chemical bond. in line with previous findings for benzene and pure azobenzene at coinage metal surfaces,   dft - d significantly overbinds the molecule, but seems to yield an accurate adsorption geometry as far as can be judged from the experimental data. comparing the _ trans _ adsorption geometry of tba and azobenzene at au(111 ) reveals a remarkable insensitivity of the structural and vibrational properties of the @xmath1 moiety.   this questions the established view of the role of the bulky tert - butyl - spacer groups for the switching of tba in terms of a mere geometric decoupling of the photochemically active diazo - bridge from the gold substrate.
considering the nonlinear electromagnetic field coupled to einstein gravity in the presence of cosmological constant, we obtain a new class of @xmath0-dimensional magnetic brane solutions.   this class of solutions yields a spacetime with a longitudinal nonlinear magnetic field generated by a static source.   these solutions have no curvature singularity and no horizons but have a conic geometry with a deficit angle @xmath1.   we investigate the effects of nonlinearity on the metric function and deficit angle and also find that for the special range of the nonlinear parameter, the solutions are not asymptotic ads.   we generalize this class of solutions to the case of spinning magnetic solutions, and find that when one or more rotation parameters are nonzero, the brane has a net electric charge which is proportional to the magnitude of the rotation parameters.   then, we use the counterterm method and compute the conserved quantities of these spacetimes.   finally, we obtain a constrain on the nonlinear parameter, such that the nonlinear electromagnetic field is conformally invariant.
the atlas bptx stations are comprised of electrostatic button pick - up detectors, located 175 m away along the beam pipe on both sides of atlas.   the pick - ups are installed as a part of the lhc beam instrumentation and used by atlas for timing purposes.   the usage of the bptx signals in atlas is twofold : they are used both in the trigger system and for lhc beam monitoring.   the bptx signals are discriminated with a constant - fraction discriminator to provide a level-1 trigger when a bunch passes through atlas.   furthermore, the bptx detectors are used by a stand - alone monitoring system for the lhc bunches and timing signals.   the bptx monitoring system measures the phase between collisions and clock with a precision better than 100 ps in order to guarantee a stable phase relationship for optimal signal sampling in the subdetector front - end electronics.   in addition to monitoring this phase, the properties of the individual bunches are measured and the structure of the beams is determined.    on september 10, 2008  , the first lhc beams reached the atlas experiment. during this period with beam,   the atlas bptx system was used extensively to time in the read - out of the sub - detectors. in this paper, we present the performance of the bptx system and its measurements of the first lhc beams.   atlas, beam monitoring, level-1 trigger, bptx, lhc, lhc timing signals
electron emission from liquid into gaseous xenon is a cornerstone of dark matter search detectors such as zeplin, xenon, lux and lz.   the probability of emission is a function of the applied electric field @xmath0, and electrons which fail to pass from the liquid into the gas have been previously hypothesized to become thermalized and trapped.   this article shows, for the first time, quantitative agreement between an electron emission model and existing data.   the model predicts that electrons in the liquid must surmount a typical potential barrier @xmath1  ev in order to escape into the gas.   this value is a factor of about @xmath2 smaller than has previously been calculated or inferred.   knowledge of @xmath3 allows calculation of the lifetime of thermalized, trapped electrons.   the value is @xmath4  ms, which appears to be compatible with xenon10 observations of electron train backgrounds.   as these backgrounds limit the sensitivity of dark sector dark matter searches, possible mitigations are discussed.
the main objective of this article is to study the dynamics of the stratified rotating boussinesq equations, which are a basic model in geophysical fluid dynamics.   first, for the case where the prandtl number is greater than one, a complete stability and bifurcation analysis near the first critical rayleigh number is carried out.   second, for the case where the prandtl number is smaller than one, the onset of the hopf bifurcation near the first critical rayleigh number is established, leading to the existence of nontrivial periodic solutions.   the analysis is based on a newly developed bifurcation and stability theory for nonlinear dynamical systems ( both finite and infinite dimensional ) by two of the authors @xcite.
we construct a reference benchmark set for atomic and molecular random - phase - approximation ( rpa ) correlation energies in a density functional theory ( dft ) framework at the complete basis set limit.   this set is used to evaluate the accuracy of some popular extrapolation schemes for rpa all - electron molecular calculations.   the results indicate that for absolute energies accurate results, clearly outperforming raw data, are achievable with two - point extrapolation schemes based on quintuple- and sextuple - zeta basis sets.   moreover, we show that results in good agreement with the benchmark can also be also obtained by using a semiempirical extrapolation procedure based on quadruple- and quintuple - zeta basis sets.   finally, we analyze the performance of different extrapolation schemes for atomization energies.
we present the results of a systematic analysis of gamma - ray burst afterglow spectral energy distributions ( seds ) in the optical / near - infrared bands.   our input list includes the entire world sample of afterglows observed in the pre-_swift _ era by the end of 2004 that have sufficient publicly available data.   we apply various dust extinction models to fit the observed seds ( milky way, large magellanic cloud and small magellanic cloud ) and derive the corresponding intrinsic extinction in the grb host galaxies and the intrinsic spectral slopes of the afterglows.   we then use these results to explore the parameter space of the power - law index of the electron distribution function and to derive the absolute magnitudes of the unextinguished afterglows.
we report the discovery of several optical burst - like events from the low - mass x - ray binary ms  1603.6 + 2600 ( uw  crb ).   the events last for a few tens of seconds, exhibit a very fast rise and slow decay, and involve optical brightening of a factor of 23.   the flares appear distinct from the lower level flickering and instead strongly resemble reprocessed type - i x - ray bursts as seen in a number of other neutron star low - mass x - ray binaries. in conjunction with the previously reported candidate x - ray burst,   these confirm that the compact object in uw  crb is a neutron star.   we examine the optical burst brightness and recurrence times and discuss how the nature of the system can be constrained.   we conclude that the source is most likely an accretion disk corona source at an intermediate distance, rather than a nearby quiescent system or very distant dipper.
we study the multiorder coherent raman scattering of a quantum probe field in a far - off - resonance medium with a prepared coherence. under the conditions of negligible dispersion and limited bandwidth  , we derive a bessel - function solution for the sideband field operators.   we analytically and numerically calculate various quantum statistical characteristics of the sideband fields.   we show that the multiorder coherent raman process can replicate the statistical properties of a single - mode quantum probe field into a broad comb of generated raman sidebands.   we also study the mixing and modulation of photon statistical properties in the case of two - mode input.   we show that the prepared raman coherence and the medium length can be used as control parameters to switch a sideband field from one type of photon statistics to another type, or from a non - squeezed state to a squeezed state and vice versa.
engineering a sensor system for detecting an extremely tiny signal such as the gravitational - wave force is a very important subject in quantum physics.   a major obstacle to this goal is that, in a simple detection setup, the measurement noise is lower bounded by the so - called standard quantum limit ( sql ), which is originated from the intrinsic mechanical back - action noise.   hence, the sensor system has to be carefully engineered so that it evades the back - action noise and eventually beats the sql. in this paper, based on the well - developed geometric control theory for classical disturbance decoupling problem  , we provide a general method for designing an auxiliary ( coherent feedback or direct interaction ) controller for the sensor system to achieve the above - mentioned goal.   this general theory is applied to a typical opto - mechanical sensor system.   also, we demonstrate a controller design for a practical situation where several experimental imperfections are present.
in a system of non - linear chemical reactions called the brusselator, we show that _ intrinsic noise _ can be regulated to drive it to exhibit resonance in the presence of a sub - threshold signal.   the phenomena of periodic stochastic resonance and aperiodic stochastic resonance, hitherto studied mostly with extrinsic noise, is demonstrated here to occur with inherent systemic noise using exact stochastic simulation algorithm due to gillespie.   the role of intrinsic noise in a couple of other phenomena is also discussed.    *   studies of noise driven regularity in non - linear systems have not been done as extensively for  intrinsic noise " as for extrinsic noise. here   we give direct demonstration of stochastic resonance ( both periodic and aperiodic ) in a chemical system with respect to intrinsic systemic fluctuations, using exact stochastic simulation method due to gillespie.   moreover, an interplay of the intrinsic and extrinsic noises is analyzed for these noise invoked resonances. *
a new class of solutions in the signum - klein - gordon model is presented.   our solutions merge properties of shock waves and compactons that appear in scalar field models with v - shaped potentials.   pacs : 03.50.kk, 05.45.-a, 11.10.lm +
in order to explore electric - field - induced transformations of polarization singularities in the polarization - resolved angular ( conoscopic ) patterns emerging after deformed helix ferroelectric liquid crystal ( dhflc ) cells with subwavelength helix pitch, we combine the transfer matrix formalism with the results for the effective dielectric tensor of biaxial flcs evaluated using an improved technique of averaging over distorted helical structures. within the framework of the transfer matrix method  , we deduce a number of symmetry relations and show that the symmetry axis of @xmath0 lines ( curves of linear polarization ) is directed along the major in - plane optical axis which rotates under the action of the electric field.   when the angle between this axis and the polarization plane of incident linearly polarized light is above its critical value, the @xmath1 points ( points of circular polarization ) appear in the form of symmetrically arranged chains of densely packed star - monstar pairs.   we also emphasize the role of phase singularities of a different kind and discuss the enhanced electro - optic response of dhflcs near the exceptional point where the condition of zero - field isotropy is fulfilled.
we present a theoretical study on the electron transmission through the ab - ba stacking boundary in multilayer graphenes. using the tight - binding model and the transfer matrix method  , we calculate the electron transmission probability through the boundary as a function of electron fermi energy in multilayers from bilayer to five - layer.   we find that the transmission is strongly suppressed particularly near the band touching point, suggesting that the electronic conductivity in general multilayer graphenes is significantly interfered by stacking fault.   the conductivity suppression by stacking fault is the strongest in the bilayer graphene, while it is gradually relaxed as increasing the number of layers. at a large carrier density  , we observe an even - odd effect where the transmission is relatively lower in trilayer and five - layer than in bilayer and four - layer, and this is related to the existence of a monolayer - like linear band in odd layers. for bilayer graphene  , we also study the effect of the perpendicular electric field opening an energy gap, and show that the band deformation enhances the electron transmission at a fixed carrier density.
a fossil bone from the archaeological site malu rosu giurgiu, in romania has been analyzed by accelerator mass spectrometry to estimate its age by determining its @xmath0c content.   the radiocarbon age of the bone is in agreement with the age obtained by the method for age determination, based on fluorine content.   this is the first radiocarbon dating for the final neolithic period, for this archaeological settlement in the romanian region.     +   email : agata@ifin.nipne.ro + national institute for physics and nuclear engineering, + po box mg-6, 76900 magurele, bucharest, romania + tel.   40 1 780 70 40
we investigate the x - ray vs. optical scaling relations of poor groups to small clusters ( @xmath0  km / s ) identified in a cosmological hydrodynamic simulation of a @xmath1cdm universe, with cooling and star formation but no pre - heating.   we find that the scaling relations between x - ray luminosity, x - ray temperature, and velocity dispersion show significant departures from the relations predicted by simple hydrostatic equilibrium models or simulations without cooling, having steeper @xmath2 and @xmath3 slopes and a  break " at @xmath4  km / s ( @xmath5  kev ).   these departures arise because the hot ( x - ray emitting ) gas fraction varies substantially with halo mass in this regime.   our predictions roughly agree with observations.   thus radiative cooling is a critical physical process in modeling galaxy groups, and may present an alternative to _ ad hoc _ models such as pre - heating or entropy floors for explaining x - ray group scaling relations.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we study a generic reaction - diffusion model for single - species population dynamics that includes reproduction, death, and competition.   the population is assumed to be confined in a refuge beyond which conditions are so harsh that they lead to certain extinction.   standard continuum mean field models in one dimension yield a critical refuge length @xmath0 such that a population in a refuge larger than this is assured survival.   herein we extend the model to take into account the discreteness and finiteness of the population, which leads us to a stochastic description.   we present a particular critical criterion for likely extinction, namely, that the standard deviation of the population be equal to the mean. according to this criterion  , we find that while survival can no longer be guaranteed for any refuge size, for sufficiently weak competition one can make the refuge large enough ( certainly larger than @xmath0 ) to cause extinction to be unlikely.   however, beyond a certain value of the competition rate parameter it is no longer possible to escape a likelihood of extinction even in an infinite refuge.   these unavoidable fluctuations therefore have a severe impact on refuge design issues.
we formulate the head - to - head matchups between major league baseball pitchers and batters from 1954 to 2008 as a bipartite network of mutually - antagonistic interactions.   we consider both the full network and single - season networks, which exhibit interesting structural changes over time.   we find interesting structure in the network and examine their sensitivity to baseball s rule changes.   we then study a biased random walk on the matchup networks as a simple and transparent way to compare the performance of players who competed under different conditions and to include information about which particular players a given player has faced.   we find that a player s position in the network does not correlate with his success in the random walker ranking but instead has a substantial effect on its sensitivity to changes in his own aggregate performance.
lensing tomography with multi - color imaging surveys can probe dark energy and the cosmological power spectrum.   however accurate photometric redshifts for tomography out to high redshift require imaging in five or more bands, which is expensive to carry out over thousands of square degrees.   since lensing makes coarse, statistical use of redshift information, we explore the prospects for tomography using limited color information from two or three band imaging. with an appropriate calibration sample  , we find that it is feasible to create up to four redshift bins using imaging data in just the @xmath0, @xmath1 and @xmath2 bands.   we construct such redshift sub - samples from mock catalogs by clustering galaxies in color space and discarding regions with poorly - defined redshift distributions.   the loss of galaxy number density decreases the accuracy of lensing measurements, but even losing half or more of the galaxies is not a severe loss for large area surveys.   we estimate the errors on lensing power spectra and dark energy parameters with color tomography and discuss trade - offs in survey area and filter choice.   we discuss the systematic errors that may change our conclusions, especially the information needed to tackle intrinsic alignments.
asymptotic quadratic growth rates of saddle connections and families of periodic cylinders on translation tori with @xmath0 marked points are studied. for any marking the existence of limits of the quadratic growth rate   is shown using elementary methods ( not ratners theorem ).   we study the growth rate limit as function of the marking.   precise formulas for this function in the case of two marked points are given and the sets where the growth rate function is maximal and continuous are described. for rational two markings the index of the veech group in @xmath1 is calculated in two different ways.
we have observed yz cnc at two day intervals from 6 to 24 april 1998, covering two full outburst cycles. the 0.1 - 2.4kev flux is lower during optical outburst than in quiescence, and lowest at the end of the outburst.   the decline of the x - ray flux in the quiescent interval appears to be in contrast to prediction of simple models for accretion - disk instabilities.   variability on @xmath0hour time scales is present, but appears not related to the orbital phase.   yz cnc was less luminous in x - rays during our 1998 observations than in earlier rosat observations.
we propose and discuss a new approach to the analysis of the correlation functions which contain light - like wilson lines or loops, the latter being cusped in addition.   the objects of interest are therefore the light - like wilson null - polygons, the soft factors of the parton distribution and fragmentation functions, high - energy scattering amplitudes in the eikonal approximation, gravitational wilson lines, etc.   our method is based on a generalization of the universal quantum dynamical principle by j. schwinger and allows one to take care of extra singularities emerging due to light - like or semi - light - like cusps.   we show that such wilson loops obey a differential equation which connects the area variations and renormalization group behavior of those objects and discuss the possible relation between geometrical structure of the loop space and area evolution of the light - like cusped wilson loops.
a discussion of an extended class of higher - derivative classical theories of gravity is presented.   a procedure is given for exhibiting the new propagating degrees of freedom, at the full non - linear level, by transforming the higher - derivative action to a canonical second - order form.   for general fourth - order theories, described by actions which are general functions of the scalar curvature, the ricci tensor and the full riemann tensor, it is shown that the higher - derivative theories may have multiple stable vacua.   the vacua are shown to be, in general, non - trivial, corresponding to desitter or anti - desitter solutions of the original theory.   it is also shown that around any vacuum the elementary excitations remain the massless graviton, a massive scalar field and a massive ghost - like spin - two field.   the analysis is extended to actions which are arbitrary functions of terms of the form @xmath0, and it is shown that such theories also have a non - trivial vacuum structure.         +
the linear response of a superfluid neutron liquid onto external vector field is studied for the case of @xmath0 pairing. in particular, we analyze the case of neutron condensation into the state with @xmath1 which is conventionally considered as the preferable one in the bulk matter of neutron stars. consideration is limited to the case when the wave - length of a perturbation is large as compared to the coherence length in the superfluid matter and the transferred energy is small in comparison with the gap amplitude.   the obtained results are used to analyse collisionless sound - like excitations of the superfluid condensate.   zero sound ( if it exists ) is found to be anisotropic and undergoes strong decrement below some temperature threshold depending substantially on the intensity of fermi - liquid interactions.
we propose and numerically simulate a semiconductor device based on coupled quantum wires, suitable for deterministic quantum teleportation of electrons trapped in the minima of surface acoustic waves.   we exploit a network of interacting semiconductor quantum wires able to provide the universal set of gates for quantum information processing, with the qubit defined by the localization of a single electron in one of two coupled channels.   the numerical approach is based on a time - dependent solution of the three - particle schrdinger equation.   first, a maximally entangled pair of electrons is obtained via coulomb interaction between carriers in different channels.   then, a complete bell - state measurement involving one electron from this pair and a third electron is performed.   finally, the teleported state is reconstructed by means of local one - qubit operations.   the large estimated fidelity explicitely suggests that an efficient teleportation process could be reached in an experimental setup.
we determine the shape, multiplicity, size, and radial structure of superclusters in the @xmath0cdm concordance cosmology from z = 0 to z = 2.   superclusters are defined as clusters of clusters in our large - scale cosmological simulation.   we find that superclusters are triaxial in shape ; many have flattened since early times to become nearly two - dimensional structures at present, with a small fraction of filamentary systems. the size and multiplicity functions   are presented at different redshifts.   supercluster sizes extend to scales of @xmath1.   the supercluster multiplicity ( richness ) increases linearly with supercluster size.   the density profile in superclusters is approximately isothermal ( @xmath2 ) and steepens on larger scales.   these results can be used as a new test of the current cosmology when compared with upcoming observations of large - scale surveys.
recently, it was shown that differential rotation is an unavoidable feature of nonlinear _ r_-modes.   we investigate the influence of this differential rotation on the detectability of gravitational waves emitted by a newly born, hot, rapidly - rotating neutron star, as it spins down due to the _ r_-mode instability.   we conclude that gravitational radiation may be detected by the advanced laser interferometer detector ligo if the amount of differential rotation at the time the _ r_-mode instability becomes active is not very high.
cosmological dynamics of scalar field with a monomial potential @xmath0 with a general background equation of state is revisited.   it is known that if @xmath1 is smaller than a critical value, the scalar field exhibits a coherent oscillation and if @xmath1 is larger it obeys a scaling solution without oscillation.   we study in detail the case where @xmath1 is equal to the critical value, and find a peculiar scalar dynamics which is neither oscillating nor scaling solution, and we call it a pseudo scaling solution.   we also discuss cosmological implications of a pseudo scaling scalar dynamics, such as the curvature perturbation and the domain wall problem.   c  u v   ut-15 - 31 +.75 in     * curvature perturbation and domain wall formation + with pseudo scaling scalar dynamics *   .75 in    yohei ema@xmath2, kazunori nakayama@xmath3 and masahiro takimoto@xmath2    0.25 in        .5 in
we have undertaken a search for the infrared emission from the intracluster dust in the coma cluster of galaxies by the multiband imaging photometer for _ spitzer_. our observations yield the deepest mid and far - infrared images of a galaxy cluster ever achieved. in each of the three bands,   we have not detected a signature of the central excess component in contrast to the previous report on the detection by _ infrared space observatory ( iso)_. we still find that the brightness ratio between 70@xmath0 m and 160@xmath0 m shows a marginal sign of the central excess, in qualitative agreement with the _ iso _ result.   our analysis suggests that the excess ratio is more likely due to faint infrared sources lying on fluctuating cirrus foreground.   our observations yield the 2@xmath1 upper limits on the excess emission within 100 kpc of the cluster center as @xmath2 mjy / sr, @xmath3 mjy / sr, and @xmath4 mjy / sr, at 24, 70, and 160 @xmath0 m, respectively.   these values are in agreement with those found in other galaxy clusters and suggest that dust is deficient near the cluster center by more than 3 orders of magnitude compared to the interstellar medium.
atmospheric erenkov telescopes are used to detect electromagnetic showers from primary gamma rays of energy @xmath0 gev   @xmath1 tev and to discriminate these from cascades due to hadrons using the erenkov images.   the geomagnetic field affects the development of showers and is shown to diffuse and distort the images.   when the component of the field normal to the shower axis is sufficiently large ( @xmath2 g ) the performance of gamma ray telescopes may be affected, although corrections should be possible.
using a green s function formulation of the superfluid current @xmath0, where a momentum @xmath1 is applied to the cooper pair, we have calculated @xmath0 as a function of @xmath1, temperature, and impurity scattering for a two - band superconductor.   we consider both renormalized bcs and full strong - coupling eliashberg theory.   there are two peaks in the current as a function of @xmath1 due to the two energy scales for the gaps and this can give rise to non - standard behavior for the critical current.   the critical current @xmath2, which is given as the maximum in @xmath0, can exhibit a kink as a function of temperature as the maximum is transferred from one peak to other.   other temperature variations are also possible and the universal bcs behavior is violated.   the details depend on the material parameters of the system, such as the amount of coupling between the bands, the gap anisotropy, the fermi velocities, and the density of states of each band.   the ginzburg - landau relation between @xmath2, the penetration depth @xmath3 and thermodynamic critical field @xmath4, is modified.   using eliashberg theory with the electron - phonon spectral densities given from bandstructure calculations, we have applied our calculations for @xmath0 and @xmath2 to the case of mgb@xmath5 and find agreement with experiment.
we investigate aggregation driven by mass injection. in this stochastic process  , mass is added with constant rate @xmath0 and clusters merge at a constant total rate @xmath1, so that both the total number of clusters and the total mass steadily grow with time.   analytic results are presented for the three classic aggregation rates @xmath2 between clusters of size @xmath3 and @xmath4.   when @xmath5, the cluster size distribution decays exponentially. when @xmath6 or @xmath7, there are two phases : ( i ) a condensate phase with a condensate containing a finite fraction of the mass in the system as well as finite clusters, and ( ii ) a cluster phase with finite clusters only. for @xmath6, the cluster size distribution, @xmath8,   has a power - law tail, @xmath9 in either phase.   the exponent is a non - monotonic function of the injection rate : @xmath10 in the condensate phase, @xmath11, and @xmath12 in the cluster phase, @xmath13.
the cms - totem precision proton spectrometer ( ct - pps ) is an approved project to add tracking and timing information at approximately @xmath0210  m from the interaction point around the cms detector.   it is designed to operate at high luminosity with up to 50 interactions per 25  ns bunch crossing to perform measurements of e.g. the quartic gauge couplings and search for rare exclusive processes. during 2016, ct - pps took data in normal high - luminosity proton - proton lhc collisions. in the coming years, high radiation doses and large multiple - vertex interactions will represent difficult challenges that resemble those of the high - luminosity lhc program. a coordinated effort of detector upgrades with the goal of reaching the physics goals while mitigating the degradation effects   is under way.   upgrades to the tracking and timing detectors are discussed.
we study the statistical properties of the sampled scale - free networks, deeply related to the proper identification of various real - world networks.   we exploit three methods of sampling and investigate the topological properties such as degree and betweenness centrality distribution, average path length, assortativity, and clustering coefficient of sampled networks compared with those of original networks.   it is found that the quantities related to those properties in sampled networks appear to be estimated quite differently for each sampling method.   we explain why such a biased estimation of quantities would emerge from the sampling procedure and give appropriate criteria for each sampling method to prevent the quantities from being overestimated or underestimated.
our original suggestion to investigate exclusive @xmath0 electroproduction as a method for extracting from data the tensor charge, transversity, and other quantities related to chiral odd generalized parton distributions is further examined.   we now explain the details of the process : _ i ) _ the connection between the helicity description and the cartesian basis ; _ ii ) _ the dependence on the momentum transfer squared, @xmath1, and _   iii ) _ the angular momentum, parity, and charge conjugation constraints ( @xmath2 quantum numbers ).
we present two simple cryogenic rf ion trap systems in which cryogenic temperatures and ultra high vacuum pressures can be reached in as little as 12 hours.   the ion traps are operated either in a liquid helium bath cryostat or in a low vibration closed cycle cryostat.   the fast turn around time and availability of buffer gas cooling made the systems ideal for testing surface - electrode ion traps.   the vibration amplitude of the closed cycled cryostat was found to be below 106 nm.   we evaluated the systems by loading surface - electrode ion traps with @xmath0sr@xmath1 ions using laser ablation, which is compatible with the cryogenic environment. using doppler cooling we observed small ion crystals in which optically resolved ions have a trapped lifetime over 2500 minutes.
two large northern polar crown prominences that erupted on 2010 april 13 and 2010 august 1 were analysed using images obtained from the _ extreme ultraviolet imager _ on the twin _ solar terrestrial relations observatory _ spacecraft.   several features along the prominence legs were reconstructed using a stereoscopic reconstruction technique developed by us.   the three - dimensional changes exhibited by the prominences can be explained as an interplay between two different motions, namely helical twist in the prominence spine, and overall non - radial equatorward motion of the entire prominence structure.   the sense of twist in both the prominences is determined from the changes in latitudes and longitudes of the reconstructed features.   the prominences are observed starting from a few hours before the eruption.   increase in height before and during the eruption allowed us to study kinematics of the prominences in the two phases of eruption, the slow rise and the fast eruptive phase.   a constant value of acceleration was found for each reconstructed feature in each phase, but it showed significant change from one leg to the other in both the prominences.   the magnitude of acceleration during the eruptive phase is found to be commensurate with the net effect of the two motions stated above.
one of the key applications for quantum computers will be the simulation of other quantum systems that arise in chemistry, materials science, etc, in order to accelerate the process of discovery.   it is important to ask : can this be achieved using near future quantum processors, of modest size and under imperfect control, or must it await the more distant era of large - scale fault - tolerant quantum computing? here   we propose a variational method involving closely integrated classical and quantum coprocessors.   we presume that all operations in the quantum coprocessor are prone to error.   the impact of such errors is minimised by _ boosting _ them artificially and then extrapolating to the zero - error case. in comparison to a more conventional optimised trotterisation technique  , we find that our protocol is efficient and appears to be fundamentally more robust against error accumulation.
we report the detection by chandra of and, two distant ( @xmath0 and @xmath1, respectively ) submillimeter sources gravitationally magnified by the galaxy cluster abell 370.   these are high - significance ( @xmath2 ) x - ray detections of the high - redshift submillimeter source population.   the x - ray positions are coincident with the optical positions to within one arcsecond.   the x - ray spectra, while of low signal - to - noise ratio, are quite hard. absorbed power law models with fixed photon indices of @xmath3 imply local absorbing columns @xmath4 @xmath5 and unabsorbed luminosities @xmath6 erg s@xmath7 in both sources.   these results imply that nuclear activity is responsible for the bulk of the luminosity in @xmath8, and for at least 20% of the luminosity of, consistent with previous optical observations.   we also place an upper limit on the x - ray flux of a third submillimeter source,. considered together with previously published chandra upper limits on x - ray flux from submillimeter sources,   our results imply that @xmath9 % of submillimeter sources exhibit x - ray emission from agn ( 90% confidence ), consistent with expectations of their contribution to the diffuse x - ray background.
in the framework of causal perturbation theory we consider a massive scalar field coupled to gravity. in the field   theoretic approach to quantum gravity ( qg ) we start with a massless second rank tensor field. this tensor field is then quantized in a covariant way in minkowski space.   this article deals with the adiabatic limit for graviton radiative corrections in a scattering process of two massive scalar particles.   we compute the differential cross - section for bremsstrahlung processes in which one of the outgoing particles emits a graviton of low energy, a so called soft graviton.   since the emited graviton will not be detected we have to integrate over all soft gravitons.
cauchy - characteristic matching ( ccm ), the combination of a central @xmath0 cauchy code with an exterior characteristic code connected across a time - like interface, is a promising technique for the generation and extraction of gravitational waves.   while it provides a tool for the exact specification of boundary conditions for the cauchy evolution, it also allows to follow gravitational radiation all the way to infinity, where it is unambiguously defined.   we present a new fourth order accurate finite difference ccm scheme for a first order reduction of the wave equation around a schwarzschild black hole in axisymmetry.   the matching at the interface between the cauchy and the characteristic regions is done by transfering appropriate characteristic / null variables.   numerical experiments indicate that the algorithm is fourth order convergent. as an application we reproduce the expected late - time tail decay for the scalar field.
the blandford - znajek process, the steady electromagnetic energy extraction from a rotating black hole, is widely believed to work for driving relativistic jets, although it is still under debate where the electric current is driven.   we address this issue analytically by investigating the time - dependent state in the boyer - lindquist and kerr - schild coordinate systems.   this analysis suggests that a non - ideal magnetohydrodynamic region is required in the time - dependent state, while not in the steady state.
in alice, open heavy - flavour production is studied through the measurements of the leptons ( electrons and muons ) from heavy - flavour hadron decays at central and forward rapidity and via the reconstruction of d - meson hadronic decays at mid - rapidity.   an overview of the open heavy - flavour production with alice in pp ( @xmath0 = 2.76 tev and 7 tev ), p  pb ( @xmath1 = 5.02 tev ) and pb  pb ( @xmath1 = 2.76 tev ) collisions will be presented.   we will discuss the production cross sections, modifications of the transverse momentum distributions, azimuthal anisotropic emissions and correlations with hadrons in comparison with various theoretical predictions.
with photon - number resolving detectors, we show compression of interference fringes with increasing photon numbers for a fabry - prot interferometer. this feature provides a higher precision in determining the position of the interference maxima compared to a classical detection strategy.   we also theoretically show supersensitivity if @xmath0-photon states are sent into the interferometer and a photon - number resolving measurement is performed.
we systematically discuss the consequences of genuine dimension - six higgs operators.   these operators are not subject to stringent constraints from electroweak precision data. however, they can modify the couplings of the higgs boson to electroweak gauge bosons and, in particular, the higgs self - interactions.   we study the sensitivity to which those couplings can be probed at future @xmath0 linear colliders in the sub - tev and in the multi - tev range.   we find that for @xmath1 gev with a luminosity of 1 ab@xmath2 the anomalous @xmath3 and @xmath4 couplings may be probed to about the @xmath5 level, and the anomalous @xmath6 coupling to about the @xmath7 level.   @xmath8 0.4 cm
we have observed the old open clusters m@xmath067 and ngc@xmath0188 with the rosat pspc. in m@xmath067   we detect a variety of x - ray sources. the x - ray emission by a cataclysmic variable, a single hot white dwarf, two contact binaries, and some rs cvn systems is as expected.   the x - ray emission by two binaries located below the subgiant branch in the hertzsprung russell diagram of the cluster, by a circular binary with a cool white dwarf, and by two eccentric binaries with @xmath1d is puzzling.   two members of ngc@xmath0188 are detected, including the fk@xmath0com type star d719.   another possible fk@xmath0com type star, probably not a member of ngc@xmath0188, is also detected.   = 0.0 mm
the theorems of vector analysis ( divergence theorem, etc. )   are typically first applied in the undergraduate physics curriculum in the context of the electromagnetic field and the differential forms of maxwell s equations. however  , these tools are analyzed in depth several courses later in the junior - senior level.   i discuss here a   bridge " problem, using the language of vector calculus in a mechanics setting to understand archimedes principle as a consequence of hydrostatic equilibrium and the superposition of the external forces.   it is my hope that this treatment will help students better integrate and understand understand these and similar vector analysis results in contexts beyond electromagnetism.
production of prompt isolated photons at hadron colliders provides a probe of perturbative qcd and can be used to study the gluon density function of the proton.   the atlas collaboration has performed precise measurements of the inclusive production of isolated prompt photons in of data collected at and in of data collected at.   the measurements are compared with state - of - the - art theory predictions at nlo in qcd and with predictions of several mc generators.   + production of inclusive jets at hadron colliders also provides a probe of perturbative qcd.   the inclusive jet production cross - section was measured in of data collected at.   results have been compared with ( state - of - the - art ) theory predictions at nlo in qcd, interfaced with different parton distribution functions.   = 1
starting with the green s functions found for normal diffusion, we construct exact time - dependent green s functions for subdiffusive equation with fractional time derivatives.   the green s functions satisfy the boundary conditions involving a linear combination of fluxes and concentrations.   the method is particularly useful to calculate the concentration profiles in a multi - part system where different kinds of transport occurs in each part of it. as an example  , we find the solution of subdiffusive equation for the system composed of two parts with normal diffusion and subdiffusion.   = 8.5 in
we study the change in the di - photon invariant mass distribution for higgs boson decays to two photons, due to interference between the higgs resonance in gluon fusion and the continuum background amplitude for @xmath0.   previously, the apparent higgs mass was found to shift by around 100 mev in the standard model in the leading order approximation, which may potentially be experimentally observable.   we compute the next - to - leading order qcd corrections to the apparent mass shift, which reduce it by about 40%. the apparent mass shift may provide a way to measure, or at least bound, the higgs boson width at the large hadron collider through `` interferometry. ''   we investigate how the shift depends on the higgs width, in a model that maintains constant higgs boson signal yields. at higgs widths above 30 mev   the mass shift is over 200 mev and increases with the square root of the width.   the apparent mass shift could be measured by comparing with the @xmath1 channel, where the shift is much smaller.   it might be possible to measure the shift more accurately by exploiting its strong dependence on the higgs transverse momentum.
the competition between reptation and rouse dynamics is incorporated in the rubinstein - duke model for polymer motion by extending it with sideways motions, which cross barriers and create or annihilate hernias. using the density - matrix renormalization - group method as solver of the master equation, the renewal time and the diffusion coefficient are calculated as function of the length of the chain and the strength of the sideways motion.   these new types of moves have a strong and delicate influence on the asymptotic behavior of long polymers.   the effects are analyzed as function of the chain length in terms of effective exponents and crossover scaling functions.   pacs 61.25.hk, 05.10.-a, 83.10.kn
we study strong coupling between plasmons in monolayer charge - doped graphene and excitons in a narrow gap semiconductor quantum well separated from graphene by a potential barrier.   we show that the coulomb interaction between excitons and plasmons result in mixed states described by a hamiltonian similar to that for exciton - polaritons and derive the exciton - plasmon coupling constant that depends on system parameters.   we calculate numerically the rabi splitting of exciton - plasmariton dispersion branches for several semiconductor materials and find that it can reach values of up to 50 - 100 mev.
we studied the question of parity breaking in a supersymmetric left - right model, in which the left - right symmetry is broken with higgs doublets ( carrying @xmath0 ). unlike the left - right symmetric models with triplet higgs scalars ( carrying @xmath1 ), in this model it is possible to break parity spontaneously by adding a parity odd singlet.   we then discussed how neutrino mass of type iii seesaw can be invoked in this model by adding extra fermion singlets.   we considered simple forms of the mass matrices that are consistent with the unification scheme and demonstrate how they can reproduce the required neutrino mixing matrix. in this model,   the baryon asymmetry of the universe is generated via leptogenesis.   the required mass scales in the model is then found to be consistent with the gauge coupling unification.
we investigate the effects of risk perception in a simple model of epidemic spreading.   we assume that the perception of the risk of being infected depends on the fraction of neighbors that are ill.   the effect of this factor is to decrease the infectivity, that therefore becomes a dynamical component of the model.   we study the problem in the mean - field approximation and by numerical simulations for regular, random and scale - free networks.   we show that for homogeneous and random networks, there is always a value of perception that stops the epidemics. in the `` worst - case '' scenario of a scale - free network with diverging input connectivity  , a linear perception can not stop the epidemics ; however we show that a non - linear increase of the perception risk may lead to the extinction of the disease.   this transition is discontinuous, and is not predicted by the mean - field analysis.
the mechanism of electroweak symmetry breaking ( ewsb ) will be directly scrutinized soon at the cern large hadron collider ( lhc ).   we analyze the lhc potential to look for new vector bosons associated with the ewsb sector, presenting a possible model independent approach to search for these new spin1 resonances.   we show that the analyses of the processes @xmath0, and @xmath1 ( with @xmath2 or @xmath3 and @xmath4 jet ) have a large reach at the lhc and can lead to the discovery or exclusion of many ewsb scenarios such as higgsless models.
within a spin wave analysis and a fermionic large - n limit, it is shown that the antiferromagnetic heisenberg model on the checkerboard lattice may have different ground states, depending on the spin size @xmath0. through an additional exchange interaction that corresponds to an inter - tetrahedra coupling  , the stability of the nel state has been explored for all cases from the square lattice to the isotropic checkerboard lattice.   away from the isotropic limit and within the linear spin wave approximation, it is shown that there exists a critical coupling for which the local magnetization of the nel state vanishes for any value of the spin @xmath0.   one the other hand, using the dyson - maleev approximation, this result is valid only in the case @xmath1 and the limit between a stable and an unstable nel state is at @xmath2. for @xmath1,   the fermionic large - n limit suggests that the ground state is a valence bond solid build with disconnected 4-spins singlets.   this analysis indicates that for low spin and in the isotropic limit, the checkerboard antiferromagnet may be close to an instability between an ordered @xmath3 ground state and a magnetized ground state.
at sron we are studying the performance of a goddard space flight center single pixel tes microcalorimeter operated in an ac bias configuration. for x - ray photons at 6 kev   the pixel shows an x - ray energy resolution @xmath0ev, which is about a factor 2 worse than the energy resolution observed in an identical dc - biased pixel. in order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field   a strong periodic dependency of the detector noise on the tes ac bias voltage is measured.   we discuss the results in the framework of the recently observed weak - link behaviour of a tes microcalorimeter.   pacs numbers :
we study the gluon propagator @xmath0 in the landau gauge in su(3 ) lattice qcd at @xmath1 = 5.7, 5.8, and 6.0 at the quenched level.   the effective gluon mass is estimated as @xmath2mev for @xmath3 fm. through the functional - form analysis of @xmath0 obtained in lattice qcd  , we find that the landau - gauge gluon propagator @xmath4 is well described by the yukawa - type function @xmath5 with @xmath6mev for @xmath7 fm in the four - dimensional euclidean space - time. in the momentum space, the gluon propagator @xmath8 with @xmath9 gev   is found to be well approximated with a new - type propagator of @xmath10, which corresponds to the four - dimensional yukawa - type propagator.   associated with the yukawa - type gluon propagator, we derive analytical expressions for the zero - spatial - momentum propagator @xmath11, the effective mass @xmath12, and the spectral function @xmath13 of the gluon field.   the mass parameter @xmath14 turns out to be the effective gluon mass in the infrared region of @xmath15 1fm. as a remarkable fact,   the obtained gluon spectral function @xmath13 is almost negative - definite for @xmath16, except for a positive @xmath17-functional peak at @xmath18.
the non - integrable dicke model and its integrable approximation, the tavis - cummings ( tc ) model, are studied as functions of both the coupling constant and the excitation energy.   the present contribution extends the analysis presented in the previous paper by focusing on the statistical properties of the quantum fluctuations in the energy spectrum and their relation with the excited state quantum phase transitions ( esqpt ).   these properties are compared with the dynamics observed in the semi - classical versions of the models.   the presence of chaos for different energies and coupling constants is exhibited, employing poincar sections and peres lattices in the classical and quantum versions, respectively.   a clear correspondence between the classical and quantum result is found for systems containing between @xmath0 to @xmath1 atoms.   a measure of the wigner character of the energy spectrum for different couplings and energy intervals is also presented employing the statistical anderson - darling test.   it is found that in the dicke model, for any coupling, a low energy regime with regular states is always present.   the richness of the onset of chaos is discussed both for finite quantum systems and for the semi - classical limit, which is exact when the number of atoms in the system tends to infinite.
the close proximity of short period hot - jupiters to their parent star means they are subject to extreme tidal forces.   this has a profound effect on their structure and, as a result, density measurements that assume that the planet is spherical can be incorrect.   we have simulated the tidally distorted surface for 34 known short period hot - jupiters, assuming surfaces of constant gravitational equipotential for the planet, and the resulting densities have been calculated based only on observed parameters of the exoplanet systems. comparing these results to the density values assuming the planets are spherical shows that there is an appreciable change in the measured density for planets with very short periods ( typically less than two days ).   for one of the shortest - period systems, wasp-19b, we determine a decrease in bulk density of 12% from the spherical case and, for the majority of systems in this study, this value is in the range of 1 - 5%. on the other - hand  , we also find cases where the distortion is negligible ( relative to the measurement errors on the planetary parameters ) even in the cases of some very short period systems, depending on the mass ratio and planetary radius.   for high - density gas - planets requiring apparently anomalously large core masses, density corrections due to tidal deformation could become important for the shortest - period systems.
the two innermost layers of the alice inner tracking system are instrumented with silicon pixel detectors.   single chip assembly prototypes of the alice pixels have been tested in high energy particle beams at the cern sps.   detection efficiency and spatial precision have been studied as a function of the threshold and the track incidence angle.   the experimental method, data analysis and main results are presented.   d.  elia@xmath0, g.  anelli@xmath1, f.  antinori@xmath2, a.  badal@xmath3, g.e.   bruno@xmath4, m.  burns@xmath1, i.a.   cali@xmath5, m.  campbell@xmath1, m.  caselle@xmath4, s.  ceresa@xmath1, p.  chochula@xmath1, m.  cinausero@xmath6, j.  conrad@xmath1, r.  dima@xmath2, d.  fabris@xmath2, r.a.   fini@xmath4, e.  fioretto@xmath6, s.  kapusta@xmath1, a.  kluge@xmath1, m.  krivda@xmath7, v.  lenti@xmath4, f.  librizzi@xmath3, m.  lunardon@xmath2, v.  manzari@xmath4, m.  morel@xmath1, s.  moretto@xmath2, p.  nilsson@xmath1, f.  osmic@xmath1, g.s.   pappalardo@xmath3
we have measured the low - frequency resistance fluctuations ( 1 mhz@xmath0f@xmath010 hz ) in ag nanowires of diameter 15 nm @xmath1 d @xmath1 200 nm at room temperatures.   the power spectral density ( psd ) of the fluctuations has a @xmath2 character as seen in metallic films and wires of larger dimension.   additionally, the psd has a significant low - frequency component and the value of @xmath3 increases from the usual 1 to @xmath4 as the diameter d is reduced.   the value of the normalized fluctuation @xmath5 also increases as the diameter d is reduced.   we observe that there are new features in the 1/f noise as the size of the wire is reduced and they become more prominent as the diameter of the wires approaches 15 nm.   it is important to investigate the origin of the new behavior as 1/f noise may become a limiting factor in the use of metal wires of nanometer dimensions as interconnects.
we theoretically investigate spin - resolved currents flowing in large - area graphene, with and without defects, doped with single atoms of noble metals ( @xmath0, @xmath1 and @xmath2 ) and @xmath3-transition metals ( @xmath4,@xmath5,@xmath6 and @xmath7 ).   we show that the presence of a local magnetic moment is a necessary but not sufficient condition to have a non zero current polarization.   an essential requirement is the presence of spin - split localized levels near the fermi energy that strongly hybridize with the graphene @xmath8 bands.   we also show that a gate potential can be used to tune the energy of these localized levels, leading to an external way to control the degree of spin - polarized current without the application of a magnetic field.
low energy supersymmetric models provide a solution to the hierarchy problem and also have the necessary ingredients to solve two of the most outstanding issues in cosmology : the origin of the baryon asymmetry and the source of dark matter. in the mssm, weak scale generation of the baryon asymmetry may be achieved in the presence of light stops, with masses lower than about 130  gev. moreover  , the proper dark matter density may be obtained in the stop   neutralino co - annihilation region, where the stop  neutralino mass difference is smaller than a few tens of gev.   searches for scalar top quarks ( stops ) in pair production processes at the tevatron and at the large hadron collider ( lhc ) become very challenging in this region of parameters. at the lhc,   however, light stops proceeding from the decay of gluino pairs may be identified, provided the gluino mass is smaller than about 900  gev. in this article   we propose an alternative method for stop searches in the co - annihilation region, based on the search for these particles in events with missing energy plus one hard photon or jet.   we show that this method is quite efficient and, when complemented with ongoing tevatron searches, allows to probe stop masses up to about 160  gev, fully probing the region of parameters consistent with electroweak baryogenesis in the mssm.
silicon photomultipliers ( sipms ) are a good alternative to photomultiplier tubes ( pmts ) because their gain and quantum efficiency are comparable to pmts.   however, the largest single - chip sipm is still less than 1  @xmath0. in order to use sipms with scintillators that have reasonable sensitivity,   it is necessary to use multiple sipms. in this work,   scintillation detectors are constructed and tested with a custom 2x2 sipm array.   the layout of the sipms and the geometry of the scintillator were determined by performing geant4 simulations.   cubic nai, csi, and clyc with 18  mm sides have been tested. the output of the scintillation detectors   are stabilized over the temperature range between 20 and 50  @xmath1c by matching the gain of the sipms in the array.   the energy resolution for these detectors has been measured as a function of temperature.   furthermore, neutron detection for the clyc detector was studied in the same temperature range. using pulse - shape discrimination,   neutrons can be cleanly identified without contribution from @xmath2-photons. as a result, these detectors are suitable for deploying in spectroscopic personal radiation detectors ( sprd ).   geant4, silicon photomultiplier, nai, csi, clyc, pulse - shape discrimination, gain stabilization, temperature, spectroscopic personal radiation detector.
a frequently confused point in studies of symmetry violation is the distinction between observer and particle transformations. in this work,   we consider a model in which a coefficient in the standard - model extension leads to violations of rotation invariance in newton s second law.   the model highlights the distinction between observer and particle transformations.
we proposed an ` ichimatsu'-decomposed lattice gauge theory with fermionic symmetries.   the vacuum structures of the gauge sector with two coupling constants ( @xmath0 ) are investigated for 3-dimensional z@xmath1 and 4-dimensional su(2 ) cases using mean - field approximation and numerical simulation.   we found two phases on the ( @xmath0 ) phase diagram for 3-dim.   z@xmath1 case, while the diagram is a single phase for the latter.
we have imaged the 880 @xmath0 m continuum emission from the `` proplyds '' in the center of the trapezium cluster in orion using the submillimeter array with a beam size @xmath1 fwhm and an rms of 2.7  mjy.   five sources are detected with fluxes in the range 18 to 38  mjy, which includes dust emission from four proplyds and ionized gas from @xmath2orig.   the total masses of the detected proplyds derived from their dust emission range from 1.3 to @xmath3 assuming a dust temperature of 20  k and mass opacity of 0.03  @xmath4  g. the eighteen other proplyds within the field - of - view were not formally detected individually, but by combining the fluxes measured at their locations, an average flux of 1.1mjy was determined for them on a statistical basis, corresponding to a mass of @xmath5.   the four detected proplyds have sufficient disk mass bound to their central stars to form planetary systems on the scale of our solar system.
in this paper we show how the student can be led to an understanding of the connection between special relativity and general relativity by considering the time dilation effect of clocks placed on the surface of the earth.   this paper is written as a socratic dialog between a lecturer sam and a student kim.
we use a modified version of moog to generate large grids of synthetic spectra in an attempt to derive quantitative abundances for three cvs ( gk per, ru peg, and ss cyg ) by comparing the models to moderate resolution ( r @xmath0 25,000 ) @xmath1-band spectra obtained with nirspec on keck. for each of the three systems we find solar, or slightly sub - solar values for , but significant deficits of carbon : for ss cyg we find  = @xmath20.50, for ru peg  = @xmath20.75, and for gk per  = @xmath21.00.   we show that it is possible to use lower resolution ( r @xmath0 2,000 ) spectra to quantify carbon deficits.   we examine realistic veiling scenarios and find that emission from h i or co can not reproduce the observations.    _   key words : _ infrared : stars  stars : cataclysmic variables  stars : individual ( ss cyg, ru peg, gk per )  stars : abundances    @xmath3 visiting observer, w. m. keck observatory, which is operated as a scientific partnership among the california institute of technology, the university of california, and the national aeronautics and space administration.   + @xmath4 visiting astronomer at the infrared telescope facility, which is operated by the university of hawaii under contract from nasa.
the object of this study is one of the most energetic and luminous molecular outflows known in the galaxy, g331.512@xmath00.103.   observations with alma band 7 ( 350 ghz ; 0.86 mm ) reveal a very compact, extremely young bipolar outflow and a more symmetric outflowing shocked shell surrounding a very small region of ionized gas.   the velocities of the bipolar outflow are about 70 km s@xmath1  on either side of the systemic velocity.   the expansion velocity of the shocked shell is @xmath224 km s@xmath1, implying a crossing time of about 2000 yr. along the symmetry axis of the outflow  , there is a velocity feature, which could be a molecular `` bullet '' of high - velocity dense material.   the source is one of the youngest examples of massive molecular outflow found associated with a high - mass star.
given an undirected graph @xmath0, the minimum sum coloring problem ( mscp ) is to find a legal assignment of colors ( represented by natural numbers ) to each vertex of @xmath0 such that the total sum of the colors assigned to the vertices is minimized.   this paper presents a memetic algorithm for mscp based on a tabu search procedure with two neighborhoods and a multi - parent crossover operator.   experiments on a set of 77 well - known dimacs and color 2002 - 2004 benchmark instances show that the proposed algorithm achieves highly competitive results in comparison with five state - of - the - art algorithms.   in particular, the proposed algorithm can improve the best known results for 17 instances.   we also provide upper bounds for 18 additional instances for the first time.   _ keywords _ : sum coloring, memetic algorithm, heuristics, combinatorial optimization   ,   ,
some of the correlations between morphological and other physical properties of planetary nebulae ( pne ) are reviewed.   in particular, the finding that bipolar ( @xmath0 ) pne have more massive progenitors than the other morphological classes is discussed in detail.   earlier results are confirmed ; including all the various sources of uncertainty, the galactic distribution of objects indicate that  are formed by stars with initial masses @xmath1  while elliptical ( @xmath2 ) pne by progenitors with masses @xmath3 .   recent results for the chemical abundances of @xmath0 and @xmath2 pne and their orientation within the galaxy are also presented.   finally, the key role in the discussion of the formation of  played by detached binary systems such as symbiotic stars is briefly discussed.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we present results of two- and three - dimensional, multi - physics simulations of an agn jet colliding with an intergalactic cloud.   the purpose of these simulations is to assess the degree of `` positive feedback, '' i.e. jet - induced star formation, that results from such a collision.   we have specifically tailored our simulation parameters to facilitate comparison with recent observations of minkowski s object ( m.o. ), a stellar nursery located at the termination point of a radio jet coming from galaxy ngc 541.   as shown in our simulations, such a collision triggers shocks which propagate around and through the cloud.   these shocks condense the gas and trigger cooling instabilities, creating runaway increases in density, to the point that individual clumps can become jeans unstable.   our simulations provide information about the expected star formation rate, total mass converted to, h@xmath0, and stars, and the relative velocity of the stars and gas.   our results confirm the possibility of jet - induced star formation, though fail to match the level observed in m.o.   we discuss ways in which the agreement might be improved in future simulations.
aiming at testing the validity of our magnesium atomic model and investigating the effects of non - local thermodynamical equilibrium ( nlte ) on the formation of the _ h_-band neutral magnesium lines, we derive the differential mg abundances from selected transitions for 13 stars either adopting or relaxing the assumption of local thermodynamical equilibrium ( lte ).   our analysis is based on high - resolution and high signal - to - noise ratio _   h_-band spectra from the apache point observatory galactic evolution experiment ( apogee ) and optical spectra from several instruments.   the absolute differences between the mg abundances derived from the two wavelength bands are always less than 0.1dex in the nlte analysis, while they are slightly larger for the lte case.   this suggests that our mg atomic model is appropriate for investigating the nlte formation of the _ h_-band mg lines.   the nlte corrections for the -band lines are sensitive to the surface gravity, becoming larger for smaller log @xmath0 values, and strong lines are more susceptible to departures from lte. for cool giants,   nlte corrections tend to be negative, and for the strong line at 15765  they reach @xmath10.14dex in our sample, and up to @xmath10.22dex for other apogee stars.   our results suggest that it is important to include nlte corrections in determining mg abundances from the _ h_-band transitions, especially when strong lines are used.
we investigate the performance of the hybrid monte carlo algorithm in updating non - trivial global topological structures. we find that the hybrid monte carlo algorithm has serious problems decorrelating the global topological charge.   this represents a warning which must be seriously considered when simulating full qcd, regardless of the number and type of fermions, with this or any similar algorithm.   simulated tempering is examined as a means of accelerating the decorrelation.
the few known @xmath0-ray binary systems are all associated with variable radio and x - ray emission.   the tev source hess j0632@xmath1057, apparently associated with the be star mwc148, is plausibly a new member of this class. following the identification of a variable x - ray counterpart to the tev source we conducted gmrt and vla observations in june - september 2008 to search for the radio counterpart of this object.   a point - like radio source at the position of the star is detected in both 1280mhz gmrt and 5ghz vla observations, with an average spectral index, @xmath2, of @xmath30.6. in the vla data   there is significant flux variability on @xmath3month timescales around the mean flux density of @xmath40.3  mjy.   these radio properties ( and the overall spectral energy distribution ) are consistent with an interpretation of hess j0632@xmath1057 as a lower power analogue of the established @xmath0-ray binary systems.       radio - continuum : stars, x - rays : binaries
we propose a startling hybrid quantum architecture for simulating a localization - delocalization transition.   the concept is based on an array of superconducting flux qubits which are coupled to a diamond crystal containing nitrogen - vacancy  ( nv ) centers.   the underlying description is a jaynes - cummings - lattice in the strong - coupling regime.   however, in contrast to well - studied coupled cavity arrays the interaction between lattice sites is mediated here by the qubit rather than by the oscillator degrees of freedom  . nevertheless, we point out that a transition between a localized and a delocalized phase occurs in this system as well. we demonstrate the possibility of monitoring this transition in a non - equilibrium scenario, including decoherence effects.   the proposed scheme allows the monitoring of localization - delocalization transitions in jaynes - cummings - lattices by use of currently available experimental technology.   contrary to cavity - coupled lattices, our proposed recourse to stylized qubit networks facilitates ( i ) to investigate localization - delocalization transitions in arbitrary dimensions and ( ii ) to tune the inter - site coupling _ in - situ_.
the fidelity decay in a microwave billiard is considered, where the coupling to an attached antenna is varied.   the resulting quantity, coupling fidelity, is experimentally studied for three different terminators of the varied antenna : a hard wall reflection, an open wall reflection, and a 50@xmath0 load, corresponding to a totally open channel.   the model description in terms of an effective hamiltonian with a complex coupling constant is given.   quantitative agreement is found with the theory obtained from a modified vwz approach [ verbaarschot  et  al, phys.   rep.  * 129 *,  367  ( 1985 ) ].
the excited state electronic structure of @xmath0 conjugated phenylene - acetylene oligomers is calculated using time - dependent density functional theory ( td - dft ) approaches.   the theoretical fluorescence spectra are analyzed in terms of frank - condon active nuclear normal modes and shown to compare well with experiment.   theoretical and experimental results for the optical absorption and emission spectra of these molecules indicate that the conjugation length can be significantly reduced by conformational rotations about the triple - bonded carbon links.   this has serious implications on the electronic functionalities of polyphenylene - acetylene based molecular wires and their possible use as charge / energy conduits in nano - assemblies.
in this work, we study the three - dimensional non - abelian noncommutative supersymmetric chern - simons model with the @xmath0 gauge group. using a superfield formulation,   we prove that, for the pure gauge theory, the green functions are one - loop finite in any gauge, if the gauge superpotential belongs to the fundamental representation of @xmath1 ; this result also holds when matter in the fundamental representation is included.   however, the cancellation of both ultraviolet and ultraviolet / infrared infrared divergences only happens in a special gauge if the coupling of the matter is in the adjoint representation.   we also look into the finite one - loop quantum corrections to the effective action : in the pure gauge sector the maxwell together with its corresponding gauge fixing action are generated ; in the matter sector, the chern - simons term is generated, inducing a shift in the classical chern - simons coefficient.
blind quantum computation ( bqc ) enables a client without enough quantum power to delegate his quantum computation to a quantum server, while keeping the input data, the algorithm and the result unknown to the server. in the studies of practical bqc protocol,   an important problem is how to reduce the quantum requirement of the client.   multi - server bqc protocols have been proposed to solve this problem.   we review the double - server and triple - server protocols [ li et al.  , phys.   rev. a 89, 040302(r ) ( 2014 ) ], and propose a modified double - server bqc protocol with a trusted center. in our protocol, the servers are allowed to communicate mutually, and the client is completely classical.   furthermore, our double - server protocol can be modified into a single - server protocol by simply combining the two servers. compared with the triple - server protocol, our double - server and single - server protocols are more simple and the client is not required to have the ability to access quantum channel.   so our protocols are more practical when quantum computer is applied in the ` cloud'model.
we present compact @xmath0-balls in an ( anti-)de sitter background in @xmath1 dimensions, obtained with a v - shaped potential of the scalar field. beyond critical values of the cosmological constant @xmath2 compact @xmath0-shells   arise. by including the gravitational back - reaction  , we obtain boson stars and boson shells with ( anti-)de sitter asymptotics.   we analyze the physical properties of these solutions and determine their domain of existence. in four dimensions we address some astrophysical aspects.
this paper reviews the status of molecular dynamics as a method in describing solid - solid phase transitions, and its relationship to continuum approaches@xcite.   simulation work done in niti and zr using first principles and semi - empirical potentials is presented.   this shows failures of extending equilibrium thermodynamics to the nanoscale, and the crucial importance of system - specific details to the dynamics of martensite formation.   the inconsistency between experimental and theoretical crystal structures in niti is described, together with its possible resolution in terms of nanoscale effects.
the first observations conducted as part of the  acis survey of 33  ( chasem33 ) sampled the eclipsing x - ray binary 7  over a large part of the 3.45 d orbital period and have resolved eclipse ingress and egress for the first time. the occurrence of the x - ray eclipse allows us to determine an improved ephemeris of mid - eclipse and binary period as hjd  @xmath0 and constrain the eclipse half angle to @xmath1.   there are indications for a shortening of the orbital period.   the x - ray spectrum is best described by a disk blackbody spectrum typical for black hole x - ray binaries in the galaxy.   we find a flat power density spectrum and no significant regular pulsations were found in the frequency range of 10@xmath20.15  hz.   hst wfpc2 images resolve the optical counterpart, which can be identified as an o6iii star with the help of extinction and colour corrections derived from the x - ray absorption.   based on the optical light curve, the mass of the compact object in the system most likely exceeds @xmath3.   this mass, the shape of the x - ray spectrum and the short term x - ray time variability identify 7  as the first eclipsing black hole high mass x - ray binary.
at the institut fr kernphysik in mainz, germany, the microtron mami has been upgraded to 1.5gev electron beam energy.   the magnetic spectrometer  is now operated by the a1 collaboration to study strangeness electro - production.   its compact design and its capability to detect negative and positive charged particles simultaneously under forward scattering angles complements the existing spectrometers. in 2008   kaon production off a liquid hydrogen target was measured at @xmath0 0.050(gev@xmath1)@xmath2 and 0.036(gev@xmath1)@xmath2.   associated @xmath3 and @xmath4 hyperons were identified in the missing mass spectra.   major modifications to the beam - line are under construction and a new electron arm focal - surface detector system was built in order to use  as a double - arm spectrometer under zero degree scattering angle.
we are concerned with few - particle correlations in a fermionic system at finite temperature and density. within the many - body green functions   formalism the description of correlations is provided by the dyson equation approach that leads to effective few - body equations.   they contain the dominant medium effects, which are self energy corrections and the pauli blocking.   hence the effective two - body interactions between quasiparticles are momentum / energy - dependent and therefore they can be usesed in the medium modified, momentum space, integral ags equations for three- and four - body systems. to investigate correlations and clusters beyond four - body, we employ, instead, the configuration space two - variable integro - differential equations ( idea ) for @xmath0-body bound systems which are based on hyperspherical harmonics and the faddeev decomposition of the wave function in two - body amplitudes.   this requires the transformation of the energy dependent two - body interactions to equivalent local, energy independent, ones.   to achieve this we use inverse scattering techniques the resulting interactions being, on and ( to all practical purposes ) off  shell equivalent to the energy dependent potentials. in this way   we obtain binding energy results for the 2, 3, 4, and 16particle in a medium at a finite temperature and various densities.   several aspects of the problem are discussed and the behavior of the potential surfaces obtained in the extreme adiabatic approximation, below and above the mott transition, is investigated.
the purpose of the paper is to introduce some conjectures regarding the analytic continuation and the arithmetic properties of quantum invariants of knotted objects.   more precisely, we package the perturbative and nonperturbative invariants of knots and 3-manifolds into two power series of type p and np, convergent in a neighborhood of zero, and we postulate their arithmetic resurgence. by the latter term, we mean analytic continuation as a multivalued analytic function in the complex numbers minus a discrete set of points, with restricted singularities, local and global monodromy. we point out some key features of arithmetic resurgence in connection to various problems of asymptotic expansions of exact and perturbative chern - simons theory with compact or complex gauge group.   finally, we discuss theoretical and experimental evidence for our conjecture.
we propose a new imaging gamma - ray detector in the mev region. by measuring the directions and energies of not only a scattered gamma ray but also a recoil electron,   the direction of an incident gamma ray would be essentially reconstructed event by event.   furthermore, one of two measured ( zenith and azimuth ) angles of a recoil electron gives us an additional redundancy which enables us to reject the background events by kinematic constraints. in order to measure   the track of a recoil electron, the micro time projection chamber(@xmath0-tpc ) has been developed, which can measure the successive positions of the track of charged particles in a few hundred micron meter pitch.   the @xmath0-tpc consists of the new type of a gas proportional chamber : micro pixel gas chamber ( @xmath0-pic ) which is one of wireless gas chambers and expected to be robust and stable. using this @xmath0-tpc and the anger camera for the detection of a scattered gamma ray  , we have obtained the first gamma - ray image by the full reconstruction of the direction of gamma rays event by event.   ,   ,   ,   ,   ,   ,   ,   ,  , gamma - ray telescopes, gas detector, nuclear gamma rays, gamma - rays astronomical observations, 95.55.k, 95.85.k, 29.30.k, 29.40.m
beginning with the projectively invariant method for linear programming, interior point methods have led to powerful algorithms for many difficult computing problems, in combinatorial optimization, logic, number theory and non - convex optimization.   algorithms for convex optimization benefitted from many pre - established ideas from classical mathematics, but non - convex problems require new concepts.   +   + lecture series i am presenting at the conference on foundations of computational mathematics, 2014, outlines some of these concepts computational models based on the concept of the continuum, algorithms invariant w.r.t.   projective, bi - rational, and bi - holomorphic transformations on co - ordinate representation, extended proof systems for more efficient certificates of optimality, extensions of grassmann s extension theory, efficient evaluation methods for the effect of exponential number of constraints, theory of connected sets based on graded connectivity, theory of curved spaces adapted to the problem data, and concept of `` relatively '' algebraic sets in curved space.   +   + since this conference does not have a proceedings, the purpose of this article is to provide the material being presented at the conference in more widely accessible form.
according to our common understandings, the original surface of a short - period comet nucleus has been lost by sublimation processes during its close approaches to the sun.   sublimation results in the formation of a dust mantle on the retreated surface and in chemical differentiation of ices over tens or hundreds of meters below the mantle. in the course of nasa s deep impact mission,   optical and infrared imaging observations of the ejecta plume were conducted by several researchers, but their interpretations of the data came as a big surprise : ( 1 ) the nucleus of comet 9p / tempel 1 is free of a dust mantle, but maintains its pristine crust of submicron   sized carbonaceous grains ; ( 2 ) primordial materials are accessible already at a depth of several tens of cm with abundant silicate grains of submicrometer sizes. in this study, we demonstrate that a standard model of cometary nuclei explains well available observational data : ( 1 ) a dust mantle with a thickness of @xmath0@xmath1  m builds up on the surface, where compact aggregates larger than tens of micrometers dominate ; ( 2 ) large fluffy aggregates are embedded in chemically differentiated layers as well as in the deepest part of the nucleus with primordial materials.   we conclude that the deep impact results do not need any peculiar view of a comet nucleus.
we investigate the evolution and number distribution of radio halos in galaxy clusters. without re - acceleration or regeneration,   the relativistic electrons responsible for the diffuse radio emission will lose their energy via inverse - compton and synchrotron losses in a rather short time, and radio halos will have lifetimes @xmath0 0.1 gyr.   radio halos could last for @xmath0 gyr if a significant level of re - acceleration is involved.   the lifetimes of radio halos would be comparable with the cosmological time if the radio - emitting electrons are mainly the secondary electrons generated by pion decay following proton - proton collisions between cosmic - ray protons and the thermal intra - cluster medium within the galaxy clusters. adopting both observational and theoretical constraints for the formation of radio halos, we calculate the formation rates and the comoving number density of radio halos in the hierarchical clustering scheme. comparing with observations, we find that the lifetimes of radio halos are @xmath0 gyr.   our results indicate that a significant level of re - acceleration is necessary for the observed radio halos and the secondary electrons may not be a dominant origin for radio halos.
we theoretically evaluate establishing remote entanglement between distinguishable matter qubits through interference and detection of two emitted photons.   the fidelity of the entanglement operation is analyzed as a function of the temporal and frequency mode - matching between the photons emitted from each quantum memory. with a general analysis  , we define limits on the absolute magnitudes of temporal and frequency mode - mismatches in order to maintain entanglement fidelities greater than 99% with two - photon detection efficiencies greater than 90%.   we apply our analysis to several selected systems of quantum memories.   results indicate that high fidelities may be achieved in each system using current experimental techniques, while maintaining acceptable rates of entanglement.   thus, it might be possible to use two - photon - mediated entanglement operations between distinguishable quantum memories to establish a network for quantum communication and distributed quantum computation.
fundamental astronomical questions on the composition of the universe, the abundance of earth - like planets, and the cause of the brightest explosions in the universe are being attacked by robotic telescopes costing billions of dollars and returning vast pipelines of data.   the success of these programs depends on the accuracy of automated real time processing of the astronomical images. in this paper   the needs of modern astronomical pipelines are discussed in the light of fuzzy - logic based decision - making.   several specific fuzzy - logic algorithms have been develop for the first time for astronomical purposes, and tested with excellent results on data from the existing night sky live sky survey.
a recently introduced `` active phase field crystal model '' describes the formation of ordered resting and traveling crystals in systems of self - propelled particles. increasing the active drive,   a resting crystal can be forced to perform collectively ordered migration as a single traveling object.   we demonstrate here that these ordered migrating structures are linearly stable. in other words, during migration, the single crystalline texture together with the globally ordered collective motion is preserved even on large length scales.   furthermore, we consider self - propelled particles on a substrate that are surrounded by a thin fluid film. we find that in this case the resulting hydrodynamic interactions can destabilize the order
in this paper, we study time - optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. in particular, we address the case where unitary transformations produced by evolutions of the coupling take much longer time as compared to the time required to produce unitary transformations on the first qubit but much shorter time as compared to the time to produce unitary transformations on the second qubit.   we present a canonical decomposition of @xmath0 in terms of the subgroup @xmath1, which is natural in understanding the time - optimal control problem of such a coupled qubit system with significantly different time scales.   a typical setting involves dynamics of a coupled electron - nuclear spin system in pulsed electron paramagnetic resonance experiments at high fields. using the proposed canonical decomposition, we give time - optimal control algorithms to synthesize various unitary transformations of interest in coherent spectroscopy and quantum information processing.
we summarize recent developments in the study of the origin of halo spin profiles and preliminary implications on disk formation.   the specific angular - momentum distributions within halos in n - body simulations match a universal shape, @xmath0.   it is characterized by a power law over most of the mass, and one shape parameter in addition to the spin parameter @xmath1.   the angular momentum tends to be aligned throughout the halo and of cylindrical symmetry.   even if angular momentum is conserved during baryonic infall, the resultant disk density profile is predicted to deviate from exponential, with a denser core and an extended tail. a slightly corrected version of the scaling relation due to linear tidal - torque theory is used to explain the origin of a typical power - law profile in shells, @xmath2 with @xmath3.   while linear theory crudely predicts the amplitudes of halo spins, it is not a good predictor of their directions.   independently, mergers of halos are found to produce a similar profile due to @xmath4 transfer from the orbit to the product halo via dynamical friction and tidal stripping.   the halo spin is correlated with having a recent major merger, though this correlation is weakened by mass loss.   these two effects are due to a correlation between the spins of neighboring halos and their orbit, leading to prograde mergers.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
two new methods to observe neutron radioactivity are presented.   both methods rely on the production and decay of the parent nucleus in flight.   the relative velocity measured between the neutron and the fragment is sensitive to half - lives between @xmath01 and @xmath0100  ps for the decay in target ( dit ) method.   the transverse position measurement of the neutron in the decay in a magnetic field ( dimf ) method is sensitive to half - lives between 10  ps and 1  ns.   neutron spectroscopy, neutron radioactivity
gas outflows appear to be a phenomenon shared by the vast majority of quasars.   observations indicate that there is wide range in outflow prominence. in this paper   we review how the 4d eigenvector 1 scheme helps to organize observed properties and lead to meaningful constraints on the outflow physical and dynamical processes.
using a sample of nearly 20,000 massive early - type galaxies selected from the sloan digital sky survey, we study the color - magnitude relation for the most luminous ( @xmath0 ) field galaxies in the redshift range @xmath1 in several colors.   the intrinsic dispersion in galaxy colors is quite small in all colors studied, but the 40 milli - mag scatter in the bluest colors is a factor of two larger than the 20 milli - mag measured in the reddest bands. while each of three simple models constructed for the star formation history in these systems can satisfy the constraints placed by our measurements, none of them produce color distributions matching those observed.   subdividing by environment, we find the dispersion for galaxies in clusters to be about 11% smaller than that of more isolated systems.   finally, having resolved the red sequence, we study the color dependence of the composite spectra.   bluer galaxies on the red sequence are found to have more young stars than red galaxies ; the extent of this spectral difference is marginally better described by passive evolution of an old stellar population than by a model consisting of a recent trace injection of young stars.
we have constructed a family of simple models for spiral galaxy evolution to allow us to investigate observational trends in star formation history with galaxy parameters.   the models are used to generate broad band colours from which ages and metallicities are derived in the same way as the data.   we generate a grid of model galaxies and select only those which lie in regions of parameter space covered by the sample.   the data are consistent with the proposition that the star formation history of a region within a galaxy depends primarily on the local surface density of the gas but that one or two additional ingredients are required to fully explain the observational data.   the observed age gradients appear steeper than those produced by the density dependent star formation law, indicating that the star formation law or infall history must vary with galactocentric radius.   furthermore, the metallicity  magnitude and age  magnitude correlations are not reproduced by a local density dependence alone.   these correlations require one or both of the following : ( i ) a combination of mass dependent infall _ and _ metal enriched outflow, or ( ii ) a mass dependent galaxy formation epoch.   distinguishing these possibilities on the basis of current data is extremely difficult.   galaxies : spiral  galaxies : stellar content  galaxies : evolution  galaxies : general
using first - principles calculations, we systematically study the dissociation of o@xmath0 molecules on different ultrathin pb(111 ) films. based on our previous work revealing the molecular adsorption precursor states for o@xmath0  , we further explore that why there are two nearly degenerate adsorption states on pb(111 ) ultrathin films, but no precursor adsorption states exist at all on the mg(0001 ) and al(111 ) surfaces. and the reason is concluded to be the different surface electronic structures. for the o@xmath0 dissociation, we consider both the reaction channels from gas - like and molecularly adsorbed o@xmath0 molecules.   we find that the energy barrier for o@xmath0 dissociation from the molecular adsorption precursor states is always smaller than from o@xmath0 gases.   the most energetically favorable dissociation process is found to be the same on different pb(111 ) films, and the energy barriers are found to be modulated by the quantum size effects of pb(111 ) films.
we test the hemispherical power asymmetry of the wmap 7-year low - resolution temperature and polarization maps.   we consider two natural estimators for such an asymmetry and exploit our implementation of an optimal angular power spectrum estimator for all the six cmb spectra. by scanning the whole sky through a sample of 24 directions, we search for asymmetries in the power spectra of the two hemispheres, comparing the results with monte carlo simulations drawn from the wmap 7-year best - fit model.   our analysis extends previous results to the polarization sector.   the level of asymmetry on the ilc temperature map is found to be compatible with previous results, whereas no significant asymmetry on the polarized spectra is detected.   we show that our results are only weakly affected by the _ a posteriori _ choice of the maximum multipole considered for the analysis.   we also forecast the capability to detect dipole modulation by our methodology at planck sensitivity.       cosmic microwave background - cosmology : theory - methods : numerical - methods : statistical - cosmology : observations
_ xmm - newton _  and _ chandra _  observations of the transient 7.8  s pulsar  are used to characterize its pulse shape and spectrum, and to facilitate a search for an optical or infrared counterpart. in outburst,   the absorbed, hard x - ray spectrum with @xmath0 and @xmath1  @xmath2 is typical of x - ray binary pulsars.   the precise _ chandra_localization in a faint state leads to the identification of a probable infrared counterpart at r.a.   = @xmath3, decl.   = @xmath4 ( j2000.0 ) with magnitudes @xmath5, @xmath6, @xmath7, and @xmath8.   if this is a highly reddened o or b star, we estimate a distance of 10  kpc, at which the maximum observed x - ray luminosity is @xmath9 ergs  s@xmath10, typical of be x - ray transients or wind - fed systems.   the minimum observed luminosity is @xmath11 ergs  s@xmath10.   we can not rule out the possibility that the companion is a red giant.   the two known x - ray outbursts of are separated by @xmath12 yr, which may be the orbital period or a multiple of it, with the neutron star in an eccentric orbit.   we also studied a late m - giant long - period variable that we found only @xmath13 from the x - ray position.   it has a pulsation period of @xmath14  yr, but is not the companion of the x - ray source.
millisecond x - ray pulsars have weak magnetic dipole moments of @xmath0tm@xmath1 compared to ordinary x - ray pulsars with dipole moments of @xmath2tm@xmath1.   for this reason a surrounding accretion disc can extend closer to the neutron star, and thus reach a higher temperature, at which the opacity is dominated by electron scattering and radiation pressure is strong.   we compute the self - similar structure of such a geometrically thin axisymmetric accretion disc with an internal dynamo.   such models produce significantly stronger torques on the neutron star than models without dynamos, and can explain the strong spin variations in some millisecond x - ray pulsars.       accretion, accretion discs  magnetic fields  mhd stars : magnetic fields  stars : neutron  x - rays : binaries  pulsars : general
future experiments of nuclear and particle physics are moving towards the high luminosity regime, in order to access suppressed processes like rare b decays or exotic charmonium resonances. in this scenario,   high rate capability is a key requirement for electronics instrumentation, together with excellent timing resolution for precise event reconstruction.   the development of dedicated frontend electronics ( fee ) for detectors has become increasingly challenging.   a current trend in r&d is towards multipurpose fee which can be easily adapted to a great variety of detectors, without impairing the required high performance.   + we report on high - precision timing solutions which utilise high - bandwidth preamplifiers and fast discriminators providing time - over - threshold information, which can be used for charge measurements or walk corrections thus improving the obtainable timing resolution.   the output signal are lvds and can be directly fed into a multi - hit tdc readout.   the performance of the electronics was investigated for single photon signals, typical for imaging cherenkov detectors. the opposite condition of light signals arising from plastic scintillators,   was also studied.   high counting rates per channel of several  mhz were achieved, and a timing resolution of better than 100  ps could be obtained in a test experiment using the full readout chain.    fast timing, single photo - electron, frontend electronics, multipurpose, time - over - threshold, pid
the brown  resnick max - stable process has proven to be well - suited for modeling extremes of complex environmental processes, but in many applications its likelihood function is intractable and inference must be based on a composite likelihood, thereby preventing the use of classical bayesian techniques. in this paper   we exploit a case in which the full likelihood of a brown  resnick process can be calculated, using componentwise maxima and their partitions in terms of individual events, and we propose two new approaches to inference.   the first estimates the partitions using declustering, while the second uses random partitions in a markov chain monte carlo algorithm.   we use these approaches to construct a bayesian hierarchical model for extreme low temperatures in northern fennoscandia.   ,   ,   ,
we explore the implications of the conservation law(s ) and the corresponding  continuity equation(s ) ", resulting from the coupling between the positional and the orientational order in main - chain polymer nematics, by showing that the vectorial and tensorial forms of these equations are in general _ not equivalent _ and can not be reduced to one another, but neither are they disjoint alternatives.   we analyze the relation between them and elucidate the fundamental role that the chain backfolding plays in the determination of their relative strength and importance.   finally, we show that the correct penalty potential in the effective free energy, implementing these conservation laws, should actually connect both the tensorial and the vectorial constraints.   we show that the consequences of the polymer chains connectivity for their consistent mesoscopic description are thus not only highly non - trivial but that its proper implementation is absolutely crucial for a consistent coarse grained description of the main - chain polymer nematics.
we study the possibility of radiative electroweak symmetry breaking where loop corrections to the mass parameter of the higgs boson trigger the symmetry breaking in various extensions of the standard model ( sm ).   although the mechanism fails in the sm, it is shown to be quite successful in several extensions which share a common feature of having an additional scalar around the tev scale.   the positive higgs mass parameter at a high energy scale is turned negative in the renormalization group flow to lower energy by the cross couplings between the scalars in the higgs potential. the type - ii seesaw model with a tev scale weak scalar triplet, a two - loop radiative neutrino mass model with new scalars at the tev scale,   the inert doublet model, scalar singlet dark matter model, and a universal seesaw model with an additional @xmath0 broken at the tev scale are studied and shown to exhibit successful radiative electroweak symmetry breaking.   osu - hep-16 - 09 +    * k.s.   babu@xmath1, ilia gogoladze@xmath2 and s. khan@xmath1 *    _ @xmath3department of physics, oklahoma state university, stillwater, oklahoma 74078, usa + _   @xmath4bartol research institute, department of physics and astronomy, university of delaware, newark, de 19716, usa _ _
it is conventionally thought that the state equation of dense matter softens and thus can not result in high maximum mass if pulsars are quark stars, and that a recently discovered @xmath0 pulsar ( psr j1614 - 2230 ) may make quark stars to be unlikely.   however, this standard point of view would be revisited and updated if quark clustering could occur in cold quark matter because of the strong coupling between quarks at realistic baryon densities of compact stars, and it is addressed that the state equation of clustering quark matter stiffs to support compact stars with maximum mass @xmath1. in this brief note, it is demonstrated that large parameter spaces are allowed for @xmath1 in a lennard - jones model of clustered quark matter, and the newly measured highest mass of psr j1614 - 2230 would be meaningful to constrain the number of quarks inside single quark - cluster, to be @xmath2.
vibrational energy transfer of the amide i mode of n - methylacetamide ( nma ) is studied theoretically using the vibrational configuration interaction method.   a quartic force field of nma is constructed at the b3lyp/6 - 31g+(d ) level of theory and its accuarcy is checked by comparing the resulting anharmonic frequencies with available theoretical and experimental values.   quantum dynamics calculations for the amide i mode excitation clarify the dominant energy transfer pathways, which sensitively depend on the anharmonic couplings among vibrational modes.   a ratio of the anharmonic coupling to the frequency mismatch is employed to predict and interpret the dominant energy flow pathways.   ,   ,   , and    vibrational configuration interaction ( vci ) method, vibrational energy relaxation ( ver ), n - methylacetamide ( nma ), quartic force field ( qff )
we review the radio very long baseline interferometry ( vlbi ) observations of the guide star,, and three compact extragalactic reference sources, made in support of the nasa / stanford gyroscope relativity mission,.   the main goal of the observations was the determination of the proper motion of  relative to the distant universe.   vlbi observations made between 1997 and 2005 yield a proper motion of  of @xmath0 @xmath1 0.09  in  and @xmath2 @xmath1 0.09  in in a celestial reference frame of extragalactic radio galaxies and quasars virtually identical to the international celestial reference frame 2 ( icrf2 ).   they also yield a parallax for  of 10.37 @xmath3 0.07  mas, corresponding to a distance of 96.4 @xmath3 0.7  pc.   the uncertainties are standard errors with statistical and estimated systematic contributions added in quadrature.   these results met the pre - launch requirements of the  mission to not discernibly degrade the estimates of the geodetic and frame - dragging effects.
we present experimental measurements of the mean energy in the vicinity of the first and second quantum resonances of the atom optics kicked rotor for a number of different experimental parameters.   our data is rescaled and compared with the one parameter @xmath0classical scaling function developed to describe the quantum resonance peaks.   additionally, experimental data is presented for the `` classical '' resonance which occurs in the limit as the kicking period goes to zero.   this resonance is found to be analogous to the quantum resonances, and a similar one - parameter classical scaling function is derived, and found to match our experimental results.   the width of the quantum and classical resonance peaks is compared, and their sub - fourier nature examined.
we study the lightest masses in the fermionic sector of an anomalous @xmath0 extension of the minimal supersymmetric standard model inspired by brane constructions.   the lsp of this model is an xwimp ( extremely weak interaction particle ) which is shown to have a relic density satisfying wmap data.   this computation is carried out numerically after having adapted the darksusy package to our case.   _ # 1#1 - 1ex _   @xmath1 ) @xmath2 ] _ # 1#1 - 1ex _
this paper deals with the problem of astrometric determination of the orbital elements of the outer planets, in particular by assessing the ability of astrometric observations to detect perturbations of the sort expected from the pioneer effect or other small perturbations to gravity.   we also show that while using simplified models of the dynamics can lead to some insights, one must be careful to not over - simplify the issues involved lest one be misled by the analysis onto false paths. specifically, we show that the current ephemeris of pluto does not preclude the existence of the pioneer effect.   we show that the orbit of pluto is simply not well enough characterized at present to make such an assertion.   a number of misunderstandings related to these topics have now propagated through the literature and have been used as a basis for drawing conclusions about the dynamics of the solar system.   thus, the objective of this paper is to address these issues.   finally, we offer some comments dealing with the complex topic of model selection and comparison.
the properties of the entanglement entropy ( ee ) of a clean cayley tree ( ct ) are studied.   the ee shows a completely different behaviour depending on the way the ct is partitioned into two regions and whether we consider the ground - state or highly excited many - particle wave function.   the ground - state ee increases logarithmically as function of number of generation if a single branch is pruned off the tree, while it grows exponentially if the region around the root is trimmed. on the other hand, in both cases the highly excited states ee grows exponentially.   implications of these results to general graphs and disordered systems are shortly discussed.
for anderson localization on the cayley tree, we study the statistics of various observables as a function of the disorder strength @xmath0 and the number @xmath1 of generations.   we first consider the landauer transmission @xmath2. in the localized phase,   its logarithm follows the traveling wave form @xmath3 where ( i ) the disorder - averaged value moves linearly @xmath4 and the localization length diverges as @xmath5 with @xmath6 ( ii ) the variable @xmath7 is a fixed random variable with a power - law tail @xmath8 for large @xmath7 with @xmath9, so that all integer moments of @xmath2 are governed by rare events. in the delocalized phase,   the transmission @xmath2 remains a finite random variable as @xmath10, and we measure near criticality the essential singularity @xmath11 with @xmath12.   we then consider the statistical properties of normalized eigenstates @xmath13, in particular the entropy @xmath14 and the inverse participation ratios ( i.p.r. )   @xmath15. in the localized phase,   the typical entropy diverges as @xmath16 with @xmath17, whereas it grows linearly @xmath18 in the delocalized phase. finally for the i.p.r.  , we explain how closely related variables propagate as traveling waves in the delocalized phase. in conclusion, both the localized phase and the delocalized phase are characterized by the traveling wave propagation of some probability distributions, and the anderson localization / delocalization transition then corresponds to a traveling / non - traveling critical point. moreover, our results point towards the existence of several length scales that diverge with different exponents @xmath19 at criticality.    # 1
we consider the dynamics of a two - level system ( qubit ) driven by strong and short resonant pulses in the framework of floquet theory.   first we derive analytical expressions for the quasienergies and floquet states of the driven system.   if the pulse amplitude varies very slowly, the system adiabatically follows the instantaneous floquet states, which acquire dynamical phases that depend on the evolution of the quasienergies over time.   the difference between the phases acquired by the two floquet states corresponds to a qubit state rotation, generalizing the notion of rabi oscillations to the case of large driving amplitudes.   if the pulse amplitude changes very fast, the evolution is non - adiabatic, with transitions taking place between the floquet states.   we quantify and analyze the nonadiabatic transitions during the pulse by employing adiabatic perturbation theory and exact numerical simulations.   we find that, for certain combinations of pulse rise and fall times and maximum driving amplitude, a destructive interference effect leads to a remarkably strong suppression of transitions between the floquet states.   this effect provides the basis of a quantum control protocol, which we name floquet interference efficient suppression of transitions in the adiabatic basis ( fiesta ), that can be used to design ultra - fast high - fidelity single - qubit quantum gates.
power efficiency is becoming an ever more important metric for both high performance and high throughput computing.   over the course of next decade it is expected that flops / watt will be a major driver for the evolution of computer architecture.   servers with large numbers of arm processors, already ubiquitous in mobile computing, are a promising alternative to traditional x86 - 64 computing.   we present the results of our initial investigations into the use of arm processors for scientific computing applications.   in particular we report the results from our work with a current generation armv7 development board to explore arm - specific issues regarding the software development environment, operating system, performance benchmarks and issues for porting high energy physics software.
we present a deep color - magnitude diagram for individual stars in the halo of the nearby spiral galaxy m81, at a projected distance of 19  kpc, based on data taken with the _ advanced camera for surveys _ on the _ hubble space telescope _ ( @xmath0 ).   the cmd reveals a red giant branch that is narrow and fairly blue, and a horizontal branch that has stars that lie mostly redward of the rr lyrae instability strip.   we derive a mean metallicity of  = 1.15 @xmath1 0.11 and age of 9 @xmath1 2 gyr for the dominant population in our field, from the shape of the red giant branch, the magnitude of the red clump, and the location of the red giant branch bump.   we compare our metallicity and age results with those found previously for stars in different locations within m81, and in the spheroids of other nearby galaxies.
we have proposed the construction of optical quantum computer ( oqc ) on regular domain structure ( rds ) crystal. by using rds crystal  , we can perform all the logical operations on one rds crystal.   moreover, rds crystals are parctically independent to the heating effects  i.e., can perform logic operations constantly without cooling the rds crystal .   also, we have proposed the quantum parallelsim i.e., parallel coherent laser beams are injected at the input of the rds crystals. by using the rds crystal   we can perform the reduce the requirements of the linear and nonlinear optical components.    * optical quantum computer based on rds crystal + *    z. sazonova + physics department, automobile @xmath0 road - construction institute ( technical university ) 64, leningradskii prospect, moscow 125829, russia +    r. singh + wave research center at general physics institute of russian academy of sciences, 38, vavilov street, moscow 117942, russia tel./fax : ( + 7 095 ) 135 - 8234 email : ranjit@dataforce.net +
we prove that, under a mild summability condition on the growth of the derivative on critical orbits any piecewise monotone interval map possibly containing discontinuities and singularities with infinite derivative ( cusp map ) admits an ergodic invariant probability measures which is absolutely continuous with respect to lebesgue measure.
computational tools for normal mode analysis, which are widely used in physics and materials science problems, are designed here in a single package called ` nmscatt ` ( normal modes & scattering ) that allows arbitrarily large systems to be handled.   the package allows inelastic neutron and x - ray scattering observables to be calculated, allowing comparison with experimental data produced at large scale facilities.   various simplification schemes are presented for analysing displacement vectors, which are otherwise too complicated to understand in very large systems.   ,    and    vibrational analysis, phonons, atomic force - field simulations, inelastic neutron / x - ray scattering, dynamical structure factor    87.15.-v,87.15.aa,63.20.dj,61.10.dp
it has recently been suggested that conduction - driven magnetohydrodynamic ( mhd ) instabilities may operate at all radii within an intracluster medium ( icm ), and profoundly affect the structure of a cluster s magnetic field. where mhd instabilities dominate the dynamics of an icm, they will re - orient magnetic field lines _ perpendicular _ to the temperature gradient inside a cooling core, or _   parallel _ to the temperature gradient outside it.   this characteristic structure of magnetic field could be probed by measurements of polarized radio emission from background sources.   motivated by this possibility we have constructed 3-d models of a magnetized cooling core cluster and calculated faraday rotation measure ( rm ) maps in the plane of the sky under realistic observing conditions.   we compare a scenario in which magnetic field geometry is characterized by conduction driven mhd instabilities to that where it is determined by isotropic turbulent motions.   we find that future high - sensitivity spectro - polarimetric measurements of rm, such as will be enabled by the _ expanded very large array _ and   _ square kilometer array _ can distinguish between these two cases with plausible exposure times.   such observations will test the existence of conduction - driven mhd instabilities in dynamically relaxed cooling core clusters.   more generally, our findings imply that observations of faraday rm should be able to discern physical mechanisms that result in qualitatively different magnetic field topologies, without a priori knowledge about the nature of the processes.
self - consistent solutions of microscopic eilenberger theory are presented for a two - dimensional model of a superconducting channel with a geometric constriction.   magnetic fields, external ones as well as those caused by the supercurrents, are included and the relevant equations are solved numerically without further assumptions.   results concerning the influence of temperature, geometric parameters, of @xmath0 and of external magnetic fields on the andreev bound states in the weak link and on the current - phase relation are presented.   we find that the andreev bound states within the junction obtain peculiar substructure when a finite supercurrent flows.   as long as the london penetration depth is comparable to or bigger than the extension of the constriction, the josephson effect is independent of @xmath1.   furthermore, the weak link is very insensitive to external magnetic fields.   features restricted to a self - consistent calculation are discussed.
we adopt the point of view that ( riemannian ) classical and ( loop - based ) quantum descriptions of geometry are macro- and micro - descriptions in the usual statistical mechanical sense.   this gives rise to the notion of geometrical entropy, which is defined as the logarithm of the number of different quantum states which correspond to one and the same classical geometry configuration ( macro - state ).   we apply this idea to gravitational degrees of freedom induced on an arbitrarily chosen in space 2-dimensional surface. considering an ` ensemble'of particularly simple quantum states,   we show that the geometrical entropy @xmath0 corresponding to a macro - state specified by a total area @xmath1 of the surface is proportional to the area @xmath2, with @xmath3 being approximately equal to @xmath4.   the result holds both for case of open and closed surfaces.   we discuss briefly physical motivations for our choice of the ensemble of quantum states.
we present new interpretation of ton s180 spectrum obtained by _   chandra _ spectrometer ( low energy transmission grating ).   several narrow absorption lines and a few emission disk lines have been successfully fitted to the data.   we have not found any significant edges accompanying line emission.   we propose the interpretation of narrow lines consistent with the paper recently written by krolik ( 2002 ), where warm absorber is strongly inhomogeneous.   such situation is possible in so called multi - phase medium, where regions with different ionization states, densities and temperatures may coexist in thermal equilibrium under constant pressure.   we illustrate this scenario with theoretical spectra of radiation transfered through a stratified cloud with constant pressure ( instead of constant density ) computed by code titan in plane parallel approximation.   detected spectral features are faint and their presence do not alter the broad band continuum.   we model the broad band continuum of ton s180 assuming an irradiated accretion disk with a dissipative warm skin.   the set of parameters appropriate for the data can not be determined uniquely but models with low values of the black hole mass have too hot and radially extended warm skin to explain the formation of soft x - ray disk lines seen in the data.
we consider a non - minimally coupled ( with gravity ) scalar field with non - canonical kinetic energy.   the form of the kinetic term is of dirac - born - infeld ( dbi ) form.we study the early evolution of the universe when it is sourced only by the k - field, as well as late time evolution when both the matter and k - field are present. for the k - field,   we have considered constant potential as well as potential inspired from boundary string field theory ( b - sft ).   we show that it is possible to have an inflationary solution in early time as well as late time accelerating phases.   the solutions also exhibit attractor properties in a sense that they do not depend on the initial conditions for certain values of the parameters.
there are many different proposals for a theory of quantum gravity. even leaving aside the fundamental difference among theories such as the string theory and the non - perturbative quantum gravity, we are still left with many ambiguities ( and/or parameters to be determined ) with regard to the choice of variables, the choice of related groups, etc.   loop quantum gravity is also in such a state.   it is interesting to search for experimental observables to distinguish these quantum schemes.   this paper investigates the loop quantum gravity effect on luminosity - redshift relation.   the quantum bounce behavior of loop quantum cosmology is found to result in multivalued correspondence in luminosity - redshift relation. and   the detail multivalued behavior can tell the difference of different quantum parameters.   the inverse volume quantum correction does not result in bounce behavior in this model, but affects luminosity - redshift relation also significantly.
new results of 300 hours of operation of the tunka array are presented.   an improved parametrization of the cherenkov light lateral distribution function ( ldf ), based on corsika monte carlo simulations and the experiment quest, has been used for the reconstruction of eas parameters.   the corrected energy spectrum in the knee region is obtained.   the mean depth of the eas maximum has been derived both from the analysis of ldf steepness and the fwhm of cerenkov light pulse.   the mean mass composition around the knee is estimated.
we derive explicit formulas for time decay, @xmath0, for the european call and put options at expiry, and use them to calculate analytical approximations to the price of the american put and early exercise boundary near expiry.   we show that for many families of non - gaussian processes used in empirical studies of financial markets, the early exercise boundary for the american put without dividends is separated from the strike price by a non - vanishing margin on the interval @xmath1. as the riskless rate vanishes and the drift decreases accordingly so   that the stock remains a martingale, the optimal exercise price goes to zero uniformly over the interval @xmath2.   the implications for parameters fitting are discussed.
the variance of difference of photocounts is an established measure of quantum correlations for quantum states of light.   it enables us to discriminate between the classical correlation of a two - mode coherent state and the quantum correlation of a twin - beam state.   we study the effect of loss and saturation of the photon - number - resolving detector on the measurement of the variance of difference of photocounts.   an analytic function is derived for this variance, both for the coherent and the twin - beam states.   it is found that the variance of difference of photocounts is no longer a reliable entanglement measure in the non - linear regime of the detector response but it remains useful in some range of values of average photon numbers of the incident light.   we also quantify the linear regime of the detector with saturation which will be useful for calibration of the detector quantum efficiency.   photon - number - resolving detectors ; quantum correlation ; saturation
we present a multirate method that is particularly suited for integrating the systems of ordinary differential equations ( odes ) that arise in step models of surface evolution.   the surface of a crystal lattice, that is slightly miscut from a plane of symmetry, consists of a series of terraces separated by steps. under the assumption of axisymmetry,   the step radii satisfy a system of odes that reflects the steps response to step line tension and step - step interactions.   two main problems arise in the numerical solution of these equations.   first, the trajectory of the innermost step can become singular, resulting in a divergent step velocity.   second, when a step bunching instability arises, the motion of steps within a bunch becomes very strongly stable, resulting in `` local stiffness ''.   the multirate method introduced in this paper ensures that small time steps are taken for singular and locally stiff components, while larger time steps are taken for the remaining ones.   special consideration is given to the construction of high order interpolants during run time which ensures fourth order accuracy of scheme for components of the solution sufficiently far away from singular trajectories.   multirate, runge kutta, interpolation, stiffness, step equations    65l05, 65l06, 82d25
in an effort to shed more light on the formation process of binary stars, we have started a program to study multiplicity among nearby low- and intermediate - mass protostars using the ovro millimeter array. here, we describe the project and present the first results on the protostellar core in the bok globule cb230 ( l1177 ). at 10  resolution,   the molecular core is resolved into two components separated by @xmath05000au.   the morphology and kinematics of the double core suggest that it formed from a single cloud core due to rotational fragmentation.   # 1_#1 _ # 1_#1 _ =    # 1 1.25 in.125 in.25 in
we investigate predictions of a minimal realistic non - supersymmetric @xmath0 grand unified theory. to accomplish unification and generate neutrino mass we introduce one extra higgs representation  a @xmath1 of @xmath0to the particle content of the minimal georgi - glashow scenario.   generic prediction of this setup is a set of rather light scalar leptoquarks. in the case of the most natural implementation of the type ii see - saw mechanism   their mass is in the phenomenologically interesting region ( @xmath2@xmath3gev ). as such  , our scenario has a potential to be tested at the next generation of collider experiments, particularly at the large hadron collider ( lhc ) at cern.   the presence of the @xmath1 generates additional contributions to proton decay which, for light scalar leptoquarks, can be more important than the usual gauge @xmath4 ones.   we exhaustively study both and show that the scenario is not excluded by current experimental bounds on nucleon lifetimes.
we give a brief history of catalan numbers, from their first discovery in the 18th century to modern times.   this note will appear as an appendix in richard stanley s forthcoming book  @xcite.   department of mathematics, ucla, los angeles, ca, 90095.  .06 cm email :.06 cm ` pak@math.ucla.edu ` ]   .9 cm
_ kepler _ will monitor a sufficient number of stars that it is likely to detect single transits of planets with periods longer than the mission lifetime.   we show that by combining the exquisite _ kepler _ photometry of such transits with precise radial velocity observations taken over a reasonable timescale ( @xmath0 months ) after the transits, and assuming circular orbits, it is possible to estimate the periods of these transiting planets to better than 20%, for planets with radii greater than that of neptune, and the masses to within a factor of 2, for planets with masses larger than or about equal to the mass of jupiter. using a fisher matrix analysis, we derive analytic estimates for the uncertainties in the velocity of the planet and the acceleration of the star at the time of transit, which we then use to derive the uncertainties for the planet mass, radius, period, semimajor axis, and orbital inclination.   finally, we explore the impact of orbital eccentricity on the estimates of these quantities.
baryons constitute about @xmath0 of our universe, but most of them are missing and we do not know where and in what form they are hidden.   this constitute the so - called missing baryon problem.   a possibility is that part of these baryons are hidden in galactic halos.   we show how the 7-year data obtained by the wmap satellite may be used to trace the halo of the nearby giant spiral galaxy m31.   we detect a temperature asymmetry in the m31 halo along the rotation direction up to about 120 kpc.   this could be the first detection of a galactic halo in microwaves and may open a new way to probe hidden baryons in these relatively less studied galactic objects using high accuracy cmb measurements.
population iii stars forming in the infant universe at z=30 heralded the end of the cosmic dark ages.   they are presumed to be assembled in so - called minihaloes with virial temperatures of a few thousand k where collapse is triggered by molecular hydrogen cooling.   a central question concerns their final masses, and whether fragmentation occurs during their formation.   while studies employing lagrangian codes suggest fragmentation via a self - gravitating disk, recent high resolution simulations indicated that disk formation is suppressed. here   we report the first high - resolution large - eddy simulations performed with the eulerian grid - based code enzo following the evolution beyond the formation of the first peak, to investigate the accretion of the central massive clump and potential fragmentation. for a total of 3 halos, we see that a disk forms around the first clump.   the central clump reaches @xmath0  solar masses after 40 years, while subsequent accretion is expected at a rate of @xmath1 solar masses per year. in one of these halos, additional clumps   form as a result of fragmentation which proceeds at larger scales.   we note that subgrid - scale turbulence yields relevant contributions to the stability of the protostellar disks.   we conclude that the first protostar may reach masses up to @xmath2, which are only limited by the effect of radiative feedback.
many techniques for measuring neutron star radii rely on absolute flux measurements in the x - rays. as a result,   one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. using the stable x - ray burster, gs  1826@xmath0238, and its simultaneous observations by chandra hetg / acis - s and rxte / pca as well as by xmm - newton epic - pn and rxte / pca  , we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts.   we find that the rxte / pca and the chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements.   in contrast, xmm - newton epic - pn measures 14.0@xmath10.3% less flux than the rxte / pca. this is consistent with the previously reported discrepancy with the flux measurements of epic - pn, compared to epic - mos1, mos2 and acis - s detectors.   we also show that any intrinsic time dependent systematic uncertainty that may exist in the calibration of the satellites has already been implicity taken into account in the neutron star radius measurements.
the membership of some galaxies in the nearby ( d @xmath0 mpc ) coma i cloud is uncertain. here we present globular cluster luminosity functions ( gclfs ) from the _ hubble space telescope _ for two bright ellipticals which may belong to this group. after fitting the gclf  , we find a turnover magnitude of @xmath1 = 23.23 @xmath2 0.11 for ngc 4278 and @xmath1 = 23.07 @xmath2 0.13 for ngc 4494.   our limiting magnitude is about two magnitudes fainter than these values, making this data among the most complete gclfs published to date.   the fitted gclf dispersions ( @xmath3 1.1@xmath4 ) are somewhat smaller than typical values for other ellipticals. assuming an absolute turnover magnitude of m@xmath5 = 7.62, and after applying a small metallicity correction, we derive distance modulii of ( m  m ) = 30.61 @xmath2 0.14 for ngc 4278 and 30.50 @xmath2 0.15 for ngc 4494.   these distance estimates are compared to other methods, and lie within the published range of values.   we conclude that both galaxies lie at the same distance and are both members of the coma i cloud.
we consider online content recommendation with implicit feedback through pairwise comparisons.   we study a new formulation of the dueling bandit problems in which arms are dependent and regret occurs when neither pulled arm is optimal.   we propose a new algorithm, _ comparing the best _   ( ctb ), with computational requirements appropriate for problems with few arms, and a variation of this algorithm whose computation scales to problems with many arms.   we show both algorithms have constant expected cumulative regret.   we demonstrate through numerical experiments on simulated and real dataset that these algorithms improve significantly over existing algorithms in the setting we study.
particle-@xmath0 coincidences from the @xmath1y(@xmath2)@xmath1y and @xmath1y(@xmath3)@xmath4y reactions were utilized to obtain @xmath0-ray spectra as function of excitation energy. the oslo method was used to extract the level density from the particle-@xmath0 coincidence matrices.   the impact of the @xmath5 shell closure on the level densities is discussed within the framework of a combinatorial quasi - particle model.
we examine the relationship between source radio luminosity and kinetic power in active galactic nucleus ( agn ) jets.   we show that neglecting various loss processes can introduce a systematic bias in the jet powers inferred from radio luminosities for a sample of radio galaxies.   this bias can be corrected for by considering source size as well as radio luminosity ; effectively the source size acts as a proxy for source age. based on a sample of fr - ii radio sources with jet powers derived from the measured hotspot parameters, we empirically determine a new expression for jet power that accounts for the source size, @xmath0, where @xmath1 is source size and @xmath2 the 151 mhz radio luminosity. by comparing a flux - limited and volume - limited sample,   we show that any derived radio luminosity   jet power relation depends sensitively on sample properties, in particular the source size distribution and the size - luminosity correlation inherent in the sample.   such bias will affect the accuracy of the kinetic luminosity function derived from lobe radio luminosities and should be treated with caution.
tree level gauge mediation ( tgm ) may be considered as the simplest way to communicate supersymmetry breaking : through the tree level renormalizable exchange of heavy gauge messengers.   we study its general structure, in particular the general form of tree level sfermion masses and of one loop, but enhanced, gaugino masses.   this allows us to set up general guidelines for model building and to identify the hypotheses underlying the phenomenological predictions. in the context of models based on the `` minimal '' gauge group so(10 ),   we show that only two `` pure '' embeddings of the mssm fields are possible using @xmath0 representations, each of them leading to specific predictions for the ratios of family universal sfermion masses at the gut scale, @xmath1 or @xmath2 ( in su(5 ) notation ).   these ratios are determined by group factors and are peculiar enough to make this scheme testable at the lhc.   we also discuss three possible approaches to the @xmath3-problem, one of them distinctive of tgm.
in the framework of left - right symmetric model, we investigate an interesting scenario, in which the so - called vev seesaw problem can be naturally solved with @xmath0@xmath1 symmetry.   in such a scenario, we find a pair of stable weakly interacting massive particles ( wimps ), which may be the cold dark matter candidates.   however, the wimp - nucleon cross section is 3 - 5 orders of magnitude above the present upper bounds from the direct dark matter detection experiments for @xmath2 gev. as a result  , the relic number density of two stable particles has to be strongly suppressed to a very small level.   nevertheless, our analysis shows that this scenario ca nt provide very large annihilation cross sections so as to give the desired relic abundance except for the resonance case. only for the case   if the rotation curves of disk galaxies are explained by the modified newtonian dynamics ( mond ), the stable wimps could be as the candidates of cold dark matter.
satellite - based quantum terminals are a feasible way to extend the reach of quantum communication protocols such as quantum key distribution ( qkd ) to the global scale. to that end  , prior demonstrations have shown qkd transmissions from airborne platforms to receivers on ground, but none have shown qkd transmissions from ground to a moving aircraft, the latter scenario having simplicity and flexibility advantages for a hypothetical satellite. here   we demonstrate, for the first time, qkd from a ground transmitter to a receiver prototype mounted on an airplane in flight.   we have specifically designed our receiver prototype to consist of many components that are compatible with the environment and resource constraints of a satellite. coupled with our relocatable ground station system, optical links with distances of were maintained and quantum signals transmitted while traversing angular rates similar to those observed of low - earth - orbit satellites.   for some passes of the aircraft over the ground station, links were established within of position data transmission, and with link times of a few minutes and received quantum bit error rates typically, we generated secure keys up to in length. by successfully generating secure keys over several different pass configurations, we demonstrate the viability of technology that constitutes a quantum receiver satellite payload and   provide a blueprint for future satellite missions to build upon.   _ keywords _ : quantum key distribution, quantum communication, quantum cryptography, quantum optics, photon detection, quantum satellite payload
we present a complete - quantum description of multi - particle szilard engine which consists of a working substance and a maxwell s demon.   the demon is modeled as a multi - level quantum system with specific quantum control and the working substance consists of identical particles obeying bose - einstein or fermi - dirac statistics. in this description, a reversible scheme to erase the demon   s memory by a lower temperature heat bath is used.   we demonstrate that ( 1 ) the quantum control of the demon can be optimized for single - particle szilard engine so that the efficiency of the demon - assisted thermodynamic cycle could reach the carnot cycle s efficiency ; ( 2 ) the low - temperature behavior of the working substance is very sensitive to the quantum statistics of the particles and the insertion position of the partition.
we study a linear threshold agent - based model ( abm ) for the spread of political revolutions on social networks using empirical network data.   we propose new techniques for building a hierarchy of simplified ordinary differential equation ( ode ) based models that aim to capture essential features of the abm, including effects of the actual networks, and give insight in the parameter regime transitions of the abm.   we relate the abm and the hierarchy of models to a population - level compartmental ode model that we proposed previously for the spread of political revolutions @xcite, which is shown to be mathematically consistent with the proposed abm and provides a way to analyze the global behaviour of the abm.   this consistency with the linear threshold abm also provides further justification a posteriori for the compartmental model of @xcite. extending concepts from epidemiological modelling  , we define a basic reproduction number @xmath0 for the linear threshold abm and apply it to predict abm behaviour on empirical networks. in small - scale numerical tests we investigate experimentally the differences in spreading behaviour that occur under the linear threshold abm model when applied to some empirical online and offline social networks, searching for quantitative evidence that political revolutions may be facilitated by the modern online social networks of social media.
the ever - increasing quality and complexity of astronomical data underscores the need for new and powerful data analysis applications.   this need has led to the development of _ sherpa _, a modeling and fitting program in the _ ciao _ software package that enables the analysis of multi - dimensional, multi - wavelength data. in this paper,   we present an overview of _ sherpa _ s features, which include : support for a wide variety of input and output data formats, including the new model descriptor list ( mdl ) format ; a model language which permits the construction of arbitrarily complex model expressions, including ones representing instrument characteristics ; a wide variety of fit statistics and methods of optimization, model comparison, and parameter estimation ; multi - dimensional visualization, provided by _ chips _ ; and new interactive analysis capabilities provided by embedding the s  lang interpreted scripting language.   we conclude by showing example _ sherpa _ analysis sessions.
in this work we study the process of energy dissipation triggered by a slow large scale motion of a magnetized conducting fluid.   our consideration is motivated by the problem of heating the solar corona, which is believed to be governed by fast reconnection events set off by the slow motion of magnetic field lines anchored in the photospheric plasma. to elucidate the physics governing the disruption of the imposed laminar motion and the energy transfer to small scales, we propose a simplified model where the large - scale motion of magnetic field lines is prescribed not at the footpoints but rather imposed volumetrically. as a result  , the problem can be treated numerically with an efficient, highly - accurate spectral method, allowing us to use a resolution and statistical ensemble exceeding those of the previous work.   we find that, even though the large - scale deformations are slow, they eventually lead to reconnection events that drive a turbulent state at smaller scales.   the small - scale turbulence displays many of the universal features of field - guided mhd turbulence like a well developed inertial range spectrum.   based on these observations, we construct a phenomenological model that gives the scalings of the amplitude of the fluctuations and the energy dissipation rate as functions of the input parameters. we find a good agreement between the numerical results and the predictions of the model.       plasma  coronae : stars.
in this paper, we propose a construction of non - binary wom ( write - once - memory ) codes for wom storages such as flash memories.   the wom codes discussed in this paper are fixed rate wom codes where messages in a fixed alphabet of size @xmath0 can be sequentially written in the wom storage at least @xmath1-times. in this paper, a wom storage is modeled by a state transition graph.   the proposed construction has the following two features.   first, it includes a systematic method to determine the encoding regions in the state transition graph.   second, the proposed construction includes a labeling method for states by using integer programming.   several novel wom codes for @xmath2 level flash memories with 2 cells are constructed by the proposed construction.   they achieve the worst numbers of writes @xmath1 that meet the known upper bound in the range @xmath3.   in addition, we constructed fixed rate non - binary wom codes with the capability to reduce ici ( inter cell interference ) of flash cells.   one of the advantages of the proposed construction is its flexibility.   it can be applied to various storage devices, to various dimensions ( i.e, number of cells ), and various kind of additional constraints.
the reweighted random series techniques provide finite - dimensional approximations to the quantum density matrix of a physical system that have fast asymptotic convergence.   we study two special reweighted techniques that are based upon the lvy - ciesielski and wiener - fourier series, respectively. in agreement with the theoretical predictions,   we demonstrate by numerical examples that the asymptotic convergence of the two reweighted methods is cubic for smooth enough potentials. for each reweighted technique, we propose some minimalist quadrature techniques for the computation of the path averages.   these quadrature techniques are designed to preserve the asymptotic convergence of the original methods.
we use a quantum trajectory - based semi - classical method to account for coulomb interaction between the photoelectron and the parent ion in the classically forbidden, sub - barrier region during strong - field tunneling ionization processes.   we show that  besides the well - known modification of the tunneling ionization probability  there is also an influence on the interference pattern in the photoelectron spectra. in the long - wavelength limit  , the shift of the intra - cycle interference fringes caused by sub - barrier coulomb effects in the laser polarization direction can be derived analytically.   we compare our results with _ ab initio _ solutions of the time - dependent schrdinger equation and find good agreement in the long - wavelength regime, whereas the standard strong field approximation fails.   we show that the nodal structure along low - order above - threshold ionization rings is also affected by sub - barrier coulomb effects.
stochastic simulations of coarse - grained protein models are used to investigate the propensity to form knots in early stages of protein folding.   the study is carried out comparatively for two homologous carbamoyltransferases, a natively - knotted n - acetylornithine carbamoyltransferase ( aotcase ) and an unknotted ornithine carbamoyltransferase ( otcase ). in addition, two different sets of pairwise amino acid interactions are considered : one promoting exclusively native interactions, and the other additionally including non - native quasi - chemical and electrostatic interactions. with the former model   neither protein show a propensity to form knots. with the additional non - native interactions,   knotting propensity remains negligible for the natively - unknotted otcase while for aotcase it is much enhanced.   analysis of the trajectories suggests that the different entanglement of the two transcarbamylases follows from the tendency of the c - terminal to point away from ( for otcase ) or approach and eventually thread ( for aotcase ) other regions of partly - folded protein.   the analysis of the otcase / aotcase pair clarifies that natively - knotted proteins can spontaneously knot during early folding stages and that non - native sequence - dependent interactions are important for promoting and disfavouring early knotting events.
the first phase of stellar evolution in the history of the universe may be dark stars, powered by dark matter heating rather than by fusion. weakly interacting massive particles, which are their own antiparticles,   can annihilate and provide an important heat source for the first stars in the the universe.   this talk presents the story of these dark stars.   we make predictions that the first stars are very massive ( @xmath0 ), cool ( 6000 k ), bright ( @xmath1 ), long - lived ( @xmath2 years ), and probable precursors to ( otherwise unexplained ) supermassive black holes.   later, once the initial dm fuel runs out and fusion sets in, dm annihilation can predominate again if the scattering cross section is strong enough, so that a dark star is born again.
information about primary transmitter location is crucial in enabling several key capabilities in cognitive radio networks, including improved spatio - temporal sensing, intelligent location - aware routing, as well as aiding spectrum policy enforcement.   compared to other proposed non - interactive localization algorithms, the weighted centroid localization ( wcl ) scheme uses only the received signal strength information, which makes it simple to implement and robust to variations in the propagation environment. in this paper   we present the first theoretical framework for wcl performance analysis in terms of its localization error distribution parameterized by node density, node placement, shadowing variance, correlation distance and inaccuracy of sensor node positioning. using this analysis  , we quantify the robustness of wcl to various physical conditions and provide design guidelines, such as node placement and spacing, for the practical deployment of wcl.   we also propose a power - efficient method for implementing wcl through a distributed cluster - based algorithm, that achieves comparable accuracy with its centralized counterpart.
the dynamical mean - field theory ( dmft ) approach to the hubbard model requires a method to solve the problem of a quantum impurity in a bath of non - interacting electrons.   iterated perturbation theory ( ipt ) has proven its effectiveness as a solver in many cases of interest. based on general principles and on comparisons with an essentially exact continuous - time quantum monte carlo ( ctqmc ) solver, here   we show that the standard implementation of ipt fails away from half - filling when the interaction strength is much larger than the bandwidth.   we propose a slight modification to the ipt algorithm that replaces one of the equations by the requirement that double occupancy calculated with ipt gives the correct value.   we call this method ipt-@xmath0.   we recover the fermi liquid ground state away from half - filling.   the fermi liquid parameters, density of states, chemical potential, energy and specific heat on the fcc lattice are calculated with both ipt-@xmath0 and ctqmc as benchmark examples.   we also calculated the resistivity and the optical conductivity within ipt-@xmath0.   particle - hole asymmetry persists even at coupling twice the bandwidth.   several algorithms that speed up the calculations are described in appendices.
we propose a new multi - object spectrograph for the vlt.   maximus ( maximum multiplex spectrograph ) will fully exploit the multiplexing capabilities of the ozpoz fibre positioner in order to extend and complement flames and vimos in covering observational parameter space, and to meet the increasing demand for multi - object spectroscopy by eso users in the next decade.
we identify the x  ray reflected component in the spectra of nova muscae 1991, a black hole transient system used as the prototype for the recent model of esin, mcclintock & narayan ( 1997 ) based on advection dominated disk solutions.   we see that the reflected spectrum is generally significantly relativistically smeared, and use this, together with the amplitude of reflection, to track the innermost extent of the accretion disk.   the optically thick disk switches from being highly ionized to nearly neutral during the transition from high to low state, and the inner radius of the disk moves outwards during the low state decline.   qualitatively, this overall trend is compatible with esin et al.s model, but quantitatively, the retreat of the inner disk during the high to low state transition is much slower than predicted.   the hard ( low state ) spectra are not produced solely by an optically thin accretion flow : optically thick material within @xmath0 is generally present.
we prove that the number of limit cycles, which bifurcate from a two - saddle loop of an analytic plane vector field @xmath0, under an arbitrary finite - parameter analytic deformation @xmath1, @xmath2, is uniformly bounded with respect to @xmath3.   2000 msc scheme numbers : 34c07, 37g15, 70k05
self - avoiding polymers in strictly two - dimensional ( @xmath0 ) melts are investigated by means of molecular dynamics simulation of a standard bead - spring model with chain lengths ranging up to @xmath1.   the chains adopt compact configurations of typical size @xmath2 with @xmath3.   the precise measurement of various distributions of internal chain distances allows a direct test of the contact exponents @xmath4, @xmath5 and @xmath6 predicted by duplantier. due to the segregation of the chains the ratio of end - to - end distance @xmath7 and   gyration radius @xmath8 becomes @xmath9 for @xmath10 and the chains are more spherical than gaussian phantom chains.   the second legendre polynomial @xmath11 of the bond vectors decays as @xmath12 measuring thus the return probability of the chain after @xmath13 steps.   the irregular chain contours are shown to be characterized by a perimeter length @xmath14 of fractal line dimension @xmath15. in agreement with the generalized porod scattering of compact objects with fractal contour the kratky representation of the intramolecular structure factor   @xmath16 reveals a strong non - monotonous behavior with @xmath17 in the intermediate regime of the wave vector @xmath18.   this may allow to confirm the predicted contour fractality in a real experiment.
we explain how hierarchical organization of biological systems emerges naturally during evolution, through a transition in the units of individuality  . we will show how these transitions are the result of competing selective forces operating at different levels of organization, each level having different units of individuality.   such a transition represents a singular point in the evolutionary process, which we will show corresponds to a phase transition in the way information is encoded, with the formation of self - reinforcing information bottlenecks.   we present an abstract model for characterizing these transitions that is quite general, applicable to many different versions of such transitions. as a concrete example, we consider the transition to multicellularity. specifically, we study a stochastic model where isolated communities of interacting individuals ( e.g. cells ) undergo a transition to higher - order individuality ( e.g. multicellularity ).   this transition is indicated by the marked decrease in the number of cells utilized to generate new communities from pre - existing ones. in this sense,   the community begins to reproduce as a whole via a decreasing number of cells.   we show that the fitness barrier to this transition is strongly reduced by horizontal gene transfer.   these features capture two of the most prominent aspects of the transition to multicellularity : the evolution of a developmental process and reproduction through a unicellular bottleneck.
this work presents a smart trespasser detection and alert system which aims to increase the amount of security as well as the likelihood of positively identifying or stopping trespassers and intruders as compared to other commonly deployed home security system.   using multiple sensors, this system can gauge the extent of danger exhibited by a person or animal in or around the home premises, and can forward certain critical information regarding the same to home owners as well as other specified persons such as relevant security authorities.   home security, wireless device network, zigbee, wifi
the giant radio galaxy m87 was observed at tev energies with the cherenkov telescopes of the h.e.s.s.   collaboration ( high energy stereoscopic system ).   the observations have been performed in the year 2003 during the comissioning phase and in 2004 with the full four telescope setup.   the observations were motivated by the measurement of the hegra collaboration which reported a @xmath0 excess of tev @xmath1-rays from the direction of m87.   the results of the h.e.s.s. observations  indicating a possible variability of tev @xmath1-ray emission from m87 ( compared to the hegra result )  are presented.
the discovery of decay products of a short - lived radioisotope ( slri ) in the allende meteorite led to the hypothesis that a supernova shock wave transported freshly synthesized slri to the presolar dense cloud core, triggered its self - gravitational collapse, and injected the slri into the core.   previous multidimensional numerical calculations of the shock - cloud collision process showed that this hypothesis is plausible when the shock wave and dense cloud core are assumed to remain isothermal at @xmath0 k, but not when compressional heating to @xmath1 k is assumed.   our two - dimensional models ( boss et al.   2008 ) with the flash2.5 adaptive mesh refinement ( amr ) hydrodynamics code have shown that a 20 km / sec shock front can simultaneously trigger collapse of a 1 @xmath2 core and inject shock wave material, provided that cooling by molecular species such as h@xmath3o, co, and h@xmath3 is included. here   we present the results for similar calculations with shock speeds ranging from 1 km / sec to 100 km / sec.   we find that shock speeds in the range from 5 km / sec to 70 km / sec are able to trigger the collapse of a 2.2 @xmath2 cloud while simultaneously injecting shock wave material : lower speed shocks do not achieve injection, while higher speed shocks do not trigger sustained collapse.   the calculations continue to support the shock - wave trigger hypothesis for the formation of the solar system, though the injection efficiencies in the present models are lower than desired.
an iterative algorithm is presented for soft - input - soft - output ( siso ) decoding of reed - solomon ( rs ) codes.   the proposed iterative algorithm uses the sum product algorithm ( spa ) in conjunction with a binary parity check matrix of the rs code.   the novelty is in reducing a submatrix of the binary parity check matrix that corresponds to less reliable bits to a sparse nature before the spa is applied at each iteration.   the proposed algorithm can be geometrically interpreted as a two - stage gradient descent with an adaptive potential function.   this adaptive procedure is crucial to the convergence behavior of the gradient descent algorithm and, therefore, significantly improves the performance.   simulation results show that the proposed decoding algorithm and its variations provide significant gain over hard decision decoding ( hdd ) and compare favorably with other popular soft decision decoding methods.    adapting the parity check matrix, gradient descent, iterative decoding, soft decision decoding, reed - solomon ( rs ) codes.
